1 IntroductionIndustrial and domestic wastewater containingheavy metal ions are increasingly discharged intothe environment especially in developing coun-tries Unlike some organic pollutants heavy metalsare not biodegradable and cannot be metabolized ordecomposed [1] They are responsible for causingdamages to the environment and can also easilyenter the food chain through a number of pathwaysand adversely affecting the health of people [2]Therefore reliable methods are needed to detectand remove heavy metals in environmental and bio-logical samples The traditional methods commonlyused for their removal from aqueous solution includeion-exchange [3] solvent extraction [4] chemical

precipitation [5] nano-filtration [6 7] reverse osmo-sis [8] and adsorption [9ndash12] Among these tech-niques adsorption is generally preferred due to itshigh efficiency low cost possibilities easy handlingand also the availability of different adsorbentsNowadays among the various solid adsorbentspolymeric chelating resins are widely used in theremoval of metal ions due to their high adsorptioncapacities and selectivity [13ndash17] Several criteriasuch as specific and fast complexation of the metalions as well as the reusability of the adsorbent areimportant in the design of metal-chelating poly-mers Synthetic chemicals including dyes have beenextensively used in many industries such as textileplastic leather tanning paper production food tech-

187

Adsorption of heavy metal ions and azo dyes by crosslinkednanochelating resins based onpoly(methylmethacrylate-co-maleic anhydride)A Masoumi M Ghaemy

Polymer research laboratory Faculty of Chemistry University of Mazandaran Babolsar Iran

Received 24 August 2013 accepted in revised form 28 October 2013

Abstract Chelating resins are suitable materials for the removal of heavy metals in water treatments A copolymerPoly(MMA-co-MA) was synthesized by radical polymerization of maleic anhydride (MA) and methyl methacrylate(MMA) characterized and transformed into multifunctional nanochelating resin beads (80ndash150 nm) via hydrolysis graft-ing and crosslink reactions The resin beads were characterized by swelling studies field emission scanning electronmicroscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR) The main purpose of this work was to deter-mine the adsorption capacity of the prepared resins (swelling ratio ~55) towards metal ions such as Hg2+ Cd2+ Cu2+ fromwater at three different pH values (3 6 and 9) Variations in pH and types of metal ions have not significantly affected thechelation capacity of these resins The maximum chelation capacity of one of the prepared resin beads (Co-g-AP3) for Hg2+

was 63 858 and 7114 mgg at pH 3 6 and 9 respectively Approximately 96 of the metal ions could be desorbed fromthe resin Adsorption capacity of these resins towards three commercial synthetic azo dyes was also investigated The max-imum adsorption of dye AY42 was 91 for the resin Co-g-AP3 at room temperature This insures the applicability of thesynthesized resins for industrial applications

Keywords industrial applications nanochelating crosslinked resin heavy metal removal dye removal

eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196Available online at wwwexpresspolymlettcomDOI 103144expresspolymlett201422

Corresponding author e-mail ghaemyumzacircopy BME-PT

nology etc They are toxic to some aquatic organ-isms and are of serious health risk to human beings[18] Many physical and chemical methods havebeen used for the treatment of chemical-containingeffluents [19ndash22] Adsorption methods have beeninvariably successful to decolorize textile effluentsalthough this application can be limited by the highcost of adsorbents This work describes preparationand characterization of nanochelating resin beadsfor the removal of heavy-metal ions and azo dyesfrom water For these reasons we have focused ourattention on the development of new class function-alized adsorbents based on the copolymer poly(MMA-co-MA) To produce efficient metal-com-plexing ligand different functional groups such ascarboxylate and amine were introduced into the net-work structure of this copolymer via hydrolysisgrafting and crosslink reactions Characterization ofthe chelating resins was carried out by swellingtests FT-IR XRD AFM and SEM The results ofadsorption of Hg2+ Cd2+ and Cu2+ ions and syntheticazo dyes such as yellow 42 (AY42) red 151 (AR151)and blue 9 (MB9) by these resin beads from waterare reported here Desorption of the metal ions fromthe pre-adsorbed resins was also examined usingHCl solution

2 Experimental21 MaterialsBenzoyl peroxide (BPO) ethylenediamine (ED)diethylenetriamine (DETA) triethylenetetramine(TETA) (MMA) (MA) 2-aminopyridine (AP) tri-ethylamine (TEA) and solvents were purchasedfrom Fluka Co (Germany) Copper chloride(CuCl22H2O) mercury chloride (HgCl2) cad-mium chloride (CdCl2) and dyes such as acid yel-low 42 (AY42) acid red 151 (AR151) and mordantblue 9 (MB9) were purchased from Aldrich-SigmaCo (Germany) All the chemicals and reagents wereanalytical grade and used as received without fur-ther purification pH adjustments were performedwith HCl and NaOH solutions

22 Synthesis(a) Synthesis of Poly(MMA-co-MA) was carried

out via free-radical polymerization of (MA) and(MMA) in the presence of benzoyl peroxide(BPO) as an initiator and under argon atmos-phere according to the procedure given in liter-

ature with slight modification [23] Briefly in a250 mL three-necked round bottom flaskequipped with a magnetic stirrer a condenserand an inlet for inert gas 233 mL (0020 mol)MMA 20 g (0020 mol) MA and 50 mL THFwere placed Then the reaction mixture wasdegassed for 30 min by argon to remove oxy-gen from the solution BPO (1 wt) was addedto the reaction mixture and refluxed under theseconditions for 8 h Finally the copolymer wasprecipitated by adding the reaction mixture intothe nonsolvent of methanol and water (12 vv)The obtained white precipitate was washed thor-oughly with water and then dried under vacuumat 80degC (yield = 96)

(b) The graft copolymer (Co-g-AP) was preparedby mixing a mole ratio of 105 of poly(MMA-co-MA)AP in 50 mL THF in a 100 mL flaskequipped with a magnetic stirrer a condenserand an inlet for inert gas Then 05 mL(0004 mol) TEA was added as a catalyst andthe reaction mixture was refluxed with stirringfor 4 h The solid product was formed by addingthe reaction mixture into n-hexane After filtra-tion the solid product was washed by n-hexaneseveral times and then dried in a vacuum ovenat 80degC (yield = 95)

(c) The hydrolyzed copolymer (Co-Hyd) was pre-pared by adding 1 g poly(MMA-co-MA) and15 mL NaOH (2 M) into a 100 mL flask equippedwith a magnetic stirrer a condenser and an inletfor inert gas The mixture was stirred at roomtemperature for 7 hours until a clear homoge-neous solution was formed The hydrolyzedproduct was recovered as precipitate from basicsolution by addition of HCl (1 M) solution Theprecipitate was separated by filtration washedseveral times with distilled water and then driedunder vacuum at 80ordmC for 12 h

(d) The crosslinked resin beads (Co-g-AP1 Co-g-AP2 Co-g-AP3) were prepared in THF by thereaction between poly(MMA-co-MA) AP as agrafting agent and a crosslink agent such as EDDETA or TETA with a mole ratio of 105025respectively 05 mL (0004 mol) TEA was usedas a catalyst of the reaction The mixture wasrefluxed for 3 h under inert gas with stirringusing an ultrasonic water bath A solid precipi-tate was formed as the reaction proceeded which

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

188

was finally filtered washed several times withTHF and dried in a vacuum oven at 80degC for12 h The yields were in the range of 94ndash98

23 Adsorption studiesTo investigate the tendency of the chelating resinbeads for the removal of heavy metal ions such asCu2+ Cd2+ and Hg2+ in aqueous solutions constantweight of dried adsorbents were used in all batchexperiments Extraction of metal ions was carriedout individually by using their chloride saltsCuCl22H2O CdCl2 and HgCl2 All experimentswere performed at room temperature by using mix-ture of 50 mg beads and 50 mL metal ion solution(initial concentration 100 mgL) in separate flaskswhich were stirred magnetically for 24 h The sus-pensions were brought to the desired pH (3 6 9) byadding NaOH (01 M) and HCl (01 M) After theadsorption was complete the mixture was filteredand the residual metal-ion content in the filtrate wasdetermined by AAS The amount of metal ionadsorbed into the unit of the chelating resin ie theadsorption capacity (Q in mmolmiddotgndash1 polymer) wascalculated on the basis of Equation (1)

(1)

where C0 and CA are the concentration (mmolL) ofmetal ion in the initial solution and in the aqueousphase after adsorption respectively V is the volumeof the aqueous phase (L) and W is the weight of theadsorbent (005 g) The efficiency for ions adsorp-tion from the solution (R []) was calculated usingEquation (2)

(2)

24 Desorption behavior For the desorption experiment the chelating resinbeads which had been adsorbed with the metal ionsaccording to the procedure set-forth in the above sec-tion was used The desorption of metal ions wascarried out in 25 mL of 02 M HCl solution [24]while the mixture was stirred at room temperaturefor 1 h After filtration the metal ion concentrationin the aqueous phase was measured by AAS Thedesorption ratio (D []) was calculated by usingEquation (3)

(3)

where A is the amount of metal ions desorbed to theelution medium [mg] and B is the amount of metalions adsorbed on the resin [mg]

25 Dyes removalTo investigate the tendency of the chelating resinbeads for the removal of dyes in aqueous solutionsconstant weight of dried adsorbents were used in allbatch experiments The chemical structures of theazo dyes are shown in Figure 1 005 g of the resinbeads (Co-g-AP3 MMA-Co-MA and Co-Hyd) and10 mL aqueous solution of a dye such as AY42AR151and MB9 (initial concentration 100 mgL)were shaken in a shaker at room temperature for 12 hwithout pH adjustment The concentration of dye inthe filtrate was determined by measuring the maxi-mum absorption intensity of each dye at the corre-sponding wavelength using a UV-vis spectropho-tometer (max = 408 nm for AY42 max = 500 nm forAR151 and max =533 nm for MB9) and the follow-ing Beer-Lambert law (Equation (4))

D 3 4 5 AB ~

100

R 5C0 2 CA

C0~100

Q 51C0 2 CA 2 ~V

WQ 5

1C0 2 CA 2 ~VW

R 5C0 2 CA

C0~100

D 3 4 5 AB ~

100

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

189

Figure 1 Chemical structural of the tested dyes AY42 (a)AR151 (b) and MB9 (c)

A0 ndash A = b(C0 ndash C) (4)

where A is the absorption of dye at a given wave-length is molar absorptivity unique to each mole-cule and varying with wavelength b is the path lengththrough the solution that the light has to travel(1 cm) and C0 (100 mgL) and C is the concentra-tion of dye in the solution before and after adsorp-tion respectively The sorption percentage of thechelating resin was calculated using Equation (5)

(5)

where W is the amount of adsorbed dye and W0 theinitial amount of dye

26 MeasurementsFT-IR analysis was carried out on a Bruker Tensor27 spectrometer (Bruker Karlsruhe Germany) X-ray diffraction (XRD) patterns were obtained on aRigakuDMax-2550 powder diffractometer with ascanning speed of 5degmiddotminndash1 in the 2$ range of 10ndash70deg The surface morphology of the beads was exam-ined by using field emission scanning electron micro -scopy (FESEM) (Model Hitachi S4160) A frag-ment of the dried bead was mounted on a FESEMsample mount and was sputter coated with gold for2min and then was mounted in FESEM and scannedat the desired magnification A PHS-3C pH-meter(Shanghai Tianyou) was used for pH measurementsThe concentration of metal ions in the solution wasmeasured by use of a flame atomic absorption spec-trophotometer (AAS) (Hewlett-Packard 3510)Atomic force microscopy (AFM Easy Scan 2 FlexAFM Swiss Co) was also used to investigate thesurface phase and topography of the resin beadsbefore and after the sorption process The concen-tration of dye in the filtrate was measured using aUV-visible spectrophotometer The gel permeationchromatography (GPC) measurements were con-ducted at 30degC with a Perkin-Elmer instrumentequipped with a differential refractometer detectorThe columns used were packed with a polystyrenedivinylbenzene copolymer (PL gel MIXED-B fromPolymer Laboratories) and THF was used as fluentat a flow rate of 1 mLmin Calibration of the instru-ment was performed with monodisperse polystyrenestandards Water absorption measurements of thechelating resins were determined gravimetrically indistilled water at room temperature Briefly 02 g

dry resin beads (Co-g-AP Co-g-AP1 Co-g-AP2 Co-g-AP3 and CondashHyd) were placed in separate 50 mLvials containing distilled water for 3 days The beadswere taken out from the water at different timeswiped using a filter paper and weighed The weightdifference before and after immersion was deter-mined and used for calculation of the swelling ratio

3 Results and discussion31 Characterization and properties of the

chelating resinsThe FT-IR spectrum of poly(MMA-co-MA) Fig-ure 2a showed characteristic absorption bands ofanhydride at 1747 1809 and 1856 cmndash1 and of estergroup in the MMA repeating unit at 1724 cmndash1 Thenumber and weight average molar masses (Mn andMw) of this copolymer were determined by GPCwere 5096middot103 and 934middot103 gmol respectivelywith distribution index of 183 Earlier studies haveindicated that carboxylic acid and amide functionalgroups in polymer backbone provide more adsorp-tion sites for heavy metal ions in wastewater Inorder to obtain chelating resins as adsorbents ofheavy metals with satisfactory adsorption capacityfollowing transformations were performed (1) poly(MMA-co-MA) was hydrolyzed with NaOH (2 M)to form carboxylate ions which then neutralized byHCl to form ndashCOOH groups along the copolymerchains (2) poly(MMA-co-MA) was reacted with

R 3 4 5 WW0~100R 3 4 5 W

W0~100

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

190

Figure 2 Representative FT-IR spectra of poly(MMA-co-MA) (a) Co-g-AP3 (b) and metal-resin complexHgndash(Condashg-AP3) (c)

AP to form an alkylamide linkage and a carboxylicacid group and (3) poly(MMA-co-MA) wasreacted with AP and a crosslink agent such as EDDETA and TETA to form a network structure withmany adsorption sites for metal ions Comparisonof the FT-IR spectra of poly(MMA-co-MA) andCo-g-AP3 as shown in Figure 2a and 2b indicatesthat characteristic bands of the anhydride linkage inpoly(MMA-co-MA) at 1747 1809 and 1856 cmndash1

disappeared after reaction with TETA and the formedamide linkage (ndashCOndashNHndash) showed absorption bandat ~1676 cmndash1 To investigate the effect of chemicalreactions in the copolymer matrix the phase mor-phology was studied using SEM Figure 3andash3cshows representative SEM images of Co-g-AP Co-g-AP3 and Co-Hyd As can be seen in these figuresthe roughness of the surface and particularly the

porous surface after hydrolysis Figure 3c shouldbe considered as a factor providing chelating abilityfor the resins On that basis the adsorbents presentan adequate morphology with disordered distribu-tion of sizes which can be the main reason of theirhigh surface ability for the removal of metal ionsTo observe morphological properties such as sur-face porosity texture and roughness micrographs ofthe surface and cross section of Co-g-AP3 before andafter metal ion adsorption were registered by usingAFM Figure 3d shows smoother surface of Co-g-AP3 before metal ion adsorption while Figure 3ereveals a predominantly hill-valley-structured surfacewith irregular pores of nanoscale topography aftermetal ion adsorption The roughness can also be seenin 3D images of the surface of metal ion adsorbedsample with their histograms show size distribu-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

191

Figure 3 Representative FESEM images of Co-g-AP (a) Co-g-AP3 (b) and CondashHyd (c) AFM images of Co-g-AP3before (d) and after (e) Hg2+ ion adsorption

tions The average size for the particles of Co-g-AP3 before adsorption is in the range of 15ndash17 nmand after metal ion adsorption is in the range of 20ndash28 nm respectively The crosslinked beads are hydro -philic matrices ie hydrogels therefore they donot dissolve in aqueous media but do swell depend-ing on the degree of crosslinking and on the hydro -philicity of the matrix The equilibrium swellingratio of the resin beads are shown in Figure 4 Sev-eral possible factors are contributing in water absorp-tion of the beads such as incorporation of hydrop -hilic amino and amide groups into the polymermatrix which increases water absorption and intro-duction of hydrophobic ndashCH2ndash units into the poly-mer structure via crosslink agent such as TETA whichreduces water uptake of the resin As can be seen inFigure 4 the copolymers Co-g-AP and Co-Hydshowed the highest water absorption These twocopolymers are not crosslinked and they are opensystems with highly hydrophilic groups of car-boxylic acids The water absorption of threecrosslinked copolymers showed order of Co-g-AP3gtCo-g-AP2gtCO-g-AP1 which depended on the chem-ical structure of the curing agent (ED DETA andTETA respectively) and the network structure TheXRD patterns of all copolymers showed only a broaddiffraction hump at about 2$ = 15ndash20 indicating theamorphous nature of the prepared resin beads

32 Adsorption of heavy metal ionsIn this research the FT-IR spectroscopy was used

to monitor the structural changes take place in thechelating resins as a result of metal-ion complexa-tion Therefore the first information about the struc-tural changes such as shift or elimination of a cer-tain band present in the starting resin as well as theappearance of new bands caused by the complexa-tion of the resin with metal ions was provided by

the FT-IR spectra The bonding mode of Hg2+ tochelating resin was examined by comparing the FT-IR spectra of poly(MMAndashcondashMA) and Co-g-AP3with the spectrum of [Hgndash(Co-g-AP3)] complex Asshown in Figure 2c the FT-IR spectrum of Hg-(Co-g-AP3) is quite different from the spectrum of poly(MMA-co-MA) in Figure 2a Two strong absorptionbands at 1401 and 1544 cmndash1 are observed in thespectrum of [Hgndash(Co-g-AP3)] complex which areassigned to the symmetric (vs COOndash) and asym-metric (vas COOndash) vibration absorption of the car-boxylic groups respectively [25] The shift of FT-IR peak for the carbonyl group of carboxylate couldindicate whether the bonding between the ligandand metal ion was covalent or ionic [26] In thisstudy there is small shift towards higher frequencywhich can be taken as evidence for formation ofcovalent bond between metal ions and carbonylgroups The absorption bands characteristic of thearomatic AP in the resin matrix are observed at 1032914 767 and 703 cmndash1 which were not influenced bythe metal complexation The adsorption capacity ofthe chelating resin beads for the tested metal ions ofCu2+ Cd2+ and Hg2+ at pH 3 6 and 9 are shown inFigure 5 The results demonstrated a relativelyweak dependency of metal ions sorption on the pHvariations A relatively high adsorption of about60ndash80 was observed at various pH values for thetested metal ions by all the chelating resin beadsAdsorbents with carboxyl sulfonic and phosphonicgroups on the surface remove adsorbates throughion exchange while those containing nitrogen suchas amine hydrazine thioamide and imidazolinegroups not only chelate cationic metal ions butalso adsorb anionic adsorbates through electrostaticinteractions [27ndash29] All the prepared resins havecarboxylic acid and amine groups as potential ionexchangecomplexing units In the acidic condi-tions the degree of protonation of amine groupsaffects their ability to bind metal ions Thereforethe relatively high adsorption of metal ions in acidicconditions could be explained by the complex for-mation between M+2 and ndashCOOH groups The ndashCOOH groups are formed as a result of reactionbetween anhydride of the copolymer and amine ofthe crosslink agent and also can be due to hydroly-sis of the ester linkage in the MMA repeating unitAs can be seen in Figure 5 the dependency of adsorp-tion capacity of these resins on the pH value isrelated to the functional groups of adsorbent and

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

192

Figure 4 Water uptake of the chelating resins

type of metal ion For example all the chelatingresins adsorbed about 55 (Q = 031 mmolg) Cd2+

at pH 3 which increased to over 81 (Q =046 mmolg) at pH 9 while adsorption of Cu2+ was73 (Q = 042 mmolg) and 87 (Q = 051 mmolg)respectively at same pH values Therefore in gen-eral a high affinity was observed for adsorption ofthe tested metal ions by all the prepared resins espe-cially by Co-Hyd and Co-g-AP3 at various pH Thiscan be due to presence of different metal ion adsorp-tion sites such as carboxylate and amine groups inthe copolymer matrix The order of adsorption per-centage changed as follows Co-g-AP3Co-HydgtCo-g-AP2gtCo-g-AP1gtCo-g-AP The order of these

three kinds of metal ion chelation on mass basis forthe single component metal is Cu2+gtCd2+gtHg2+This affinity trend is presented on the mass basis[mg] metal chelation per gram resin beads and theseunits are important in quantifying respective metalcapacities in real terms Incorporation of TETA ascrosslinking agent with long alkyl chain and fouramine groups into the resin structure has signifi-cantly increased the adsorption capacity of the net-work The results show that the adsorption capacitywith Hg2+ (at pH = 6) is 714 mgg for Co-Hyd7263 mgg for Co-g-AP 73 mgg for Co-g-AP1763 mgg for Co-g-AP2 and 858 mgg for Co-g-AP3 Figure 6 illustrates the metal ions binding ontothe chelating resins Adsorbents used in heavy metalions removal are in particulate form in most of thecases In the literature different affinity sorbentswith a wide range of adsorption capacities for heavymetal ions have been reported Shreedhara-Murthyand Ryan found 5ndash27 mgg Cu(II) removal by cel-lulose dithiocarbamate resins [30] Roozemondshowed 32 mgg Cu(II) with pyrazole-containingpoly(styrene-divinyl-benzene) sorbents [31] Say etal [32] achieved 7141 4688 and 6394 mggadsorption capacities for Pb(II) Cr(III) and Cd(II)respectively with poly(HEMA-MAH) beads Karaet al [33] have prepared poly(EGDMA-VIM) beadsand found the chelation capacities of these beadswere 694 and 1148 mgg for Cd(II) and Pb(II)respectively Duran et al [34] have prepared [poly(VP-PEGMA-EGDMA)] beads and found the chela-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

193

Figure 5 Effect of the initial pH of the testing solutions onthe adsorption capacity (Q) and percentage (R[]) for the tested metal ions Initial ion concen-tration = 100 mgL sample dose = 5 mg50 mLtemperature = 25degC and contact time = 24 h

Figure 6 Illustration of metalndashchelating resin complexes ofCo-Hyd Co-g-AP and the crosslinked chelatingresin

tion capacities of these beads were 1823 16501581 and 1825 mgg for Pb(II) Cd(II) Cr(III) andCu(II) respectively

33 Desorption of metal ions from thechelating resin

The repeated use of the resins is an essential param-eter in improving process economics Desorption ofmetal ions from resinndashmetal ion complexes wascarried out by HCl (02 M ) treatment at room tem-perature and the amount of metal ions desorbed in 1hour was measured As shown in Figure 7 morethan 96 of adsorbed metal ions are recovered inthe acid leaching process indicating that chelation(ie binding of heavy metal ions with functionalgroups in resin) is completely reversible In order toobtain the reusability of the resins chelationndashelu-tion cycle was repeated successfully five times byusing the same adsorbent and the results are shownin Figure 7

34 Dyes removalThe adsorption of dyes with the prepared chelatingresin beads was carried out by using three commer-cial azo dyes containing different functional groupssuch as ndashN=Nndash chlorine oxadiazine and sulfate(Figure 1) The results for the dyes adsorption areshown in Figure 8 The order for the dyes removalby the resins is Co-g-AP3gtCo-Hydgt poly(MMA-co-MA) indicating higher capacity for the cross -linked resin in comparison with the results obtained

for the unmodified copolymer This can be due topresence of network structure with different func-tional groups in the modified resin (Co-g-AP3)which can accommodate large molecules and inter-act with the functional groups present in the dyemolecules Also the relatively high adsorption per-centage of Co-Hyd resin can be due to highly poresstructure of this resin as shown in Figure 3c

4 ConclusionsAdsorption represents a potentially cost-effectiveway of eliminating toxic heavy metals from indus-trial wastewaters Reusable polymer-based adsor-bents have been recognized as a promising class oflow-cost adsorbents for the removal of heavy-metalions from aqueous waste streams In this study thereaction of AP and different crosslink agents withpoly(MMA-co-MA) led to the synthesis of signifi-cantly capable chelating resins for the removal ofheavy metal ions such as Cu2+ Cd2+ and Hg2+ fromaqueous solution These results suggest that the pre-pared chelating resin beads are good heavy metalions adsorbents in various pH values and can havegreat potential applications in environmental pro-tection The affinity order of metal ions on a molarbasis is as Cu2+gtCd2+gtHg2+ The new adsorbentshave higher adsorption properties than other adsor-bents reported by some researchers In addition thecapacity of dyes removal of the resin beads wasinvestigated and the results showed that the adsorbeddye increased by using crosslinked resin

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

194

Figure 7 Desorption of Hg2+ ion from the chelating resinsbeads that had been preadsorbed under condi-tions given in Figure 6 as a function of submer-sion time in 25 mL of HCl (02 M) solution for1 h at 25degC

Figure 8 Dyes removal efficiency by the prepared resinbeads (005 g of the chelating resin in 10 mLaqueous solution containing a dye with initialconcentration = 100 mgL at 25degC for 12 h with-out pH adjustment)

References [1] Matsuto T Jung C H Tanaka N Material and heavy

metal balance in a recycling facility for home electri-cal appliances Waste Management 24 425ndash436 (2004)DOI 101016jwasman200312002

[2] Srivastava N K Majumder C B Novel biofiltrationmethods for the treatment of heavy metals from indus-trial wastewater Journal of Hazardous Materials 1511ndash8 (2008)DOI 101016jjhazmat200709101

[3] Vaaramaa K Lehto J Removal of metals and anionsfrom drinking water by ion exchange Desalination155 157ndash170 (2003)DOI 101016S0011-9164(03)00293-5

[4] ernaacute M Use of solvent extraction for the removal ofheavy metals from liquid wastes Environmental Mon-itoring and Assessment 34 151ndash162 (1995) DOI 101007BF00546029

[5] Hu X Li Y Wang Y Li X Li H Liu X Zhang PAdsorption kinetics thermodynamics and isotherm ofthiacalix[4]arene-loaded resin to heavy metal ionsDesalination 259 76ndash83 (2010)DOI 101016jdesal201004032

[6] Al-Rashdi B A M Johnson D J Hilal N Removalof heavy metal ions by nanofiltration Desalination315 2ndash17 (2013)DOI 101016jdesal201205022

[7] Ozaki H Sharma K Saktaywin W Performance ofan ultra-low-pressure reverse osmosis membrane(ULPROM) for separating heavy metal effects of inter-ference parameters Desalination 144 287ndash294 (2002)DOI 101016S0011-9164(02)00329-6

[8] Peterskovaacute M Valderrama C Gibert O Cortina JL Extraction of valuable metal ions (Cs Rb Li U)from reverse osmosis concentrate using selective sor-bents Desalination 286 316ndash323 (2012)DOI 101016jdesal201111042

[9] Soleimani Lashkenari M Davodi B Ghorbani MEisazadeh H Use of core-shell polyanilinepoly-styrene nanocomposite for removal of Cr(VI) HighPerformance Polymers 24 345ndash355 (2012)DOI 1011770954008311436222

[10] Li L Li Y Luo X Deng J Yang W Helical poly(N-propargylamide)s with functional catechol groupsSynthesis and adsorption of metal ions in aqueoussolution Reactive and Functional Polymers 70 938ndash943 (2010)DOI 101016jreactfunctpolym201009006

[11] Jitjaicham S Kampalanonwat P Supaphol P Metaladsorption behavior of 24-dinitrophenyl hydrazinemodified polyacrylonitrile nanofibers Express Poly-mer Letters 7 832ndash841 (2013)DOI 103144expresspolymlett201380

[12] Co$kun R Soykan C Saccedilak M Removal of someheavy metal ions from aqueous solution by adsorptionusing poly(ethylene terephthalate)-g-itaconic acidacryl -amide fiber Reactive and Functional Polymers 66599ndash608 (2006)DOI 101016jreactfunctpolym200510012

[13] Sankar R Sasidaran M Kaliyappan T Synthesischaracterization thermal and chelation properties ofnew polymeric hydrazone based on 24-dihydroxy ben-zaldehyde High Performance Polymers 23 32ndash39(2011)DOI 1011770954008310381148

[14] Sasidaran M Sankar R Kandasamy P Vijayalak-shmi S Kaliyappan T Chelating and biological prop-erties of an azo polymer resin Synthesis characteriza-tion and its application High Performance Polymers23 602ndash609 (2011)DOI 1011770954008311428531

[15] Dinu M V Dragan E S Heavy metals adsorption onsome iminodiacetate chelating resins as a function ofthe adsorption parameters Reactive and FunctionalPolymers 68 1346ndash1354 (2008)DOI 101016jreactfunctpolym200806011

[16] Vasconcelos H L Faacutevere V T Gonccedilalves N SLaranjeira M C M Chitosan modified with ReactiveBlue 2 dye on adsorption equilibrium of Cu(II) andNi(II) ions Reactive and Functional Polymers 671052ndash1060 (2007)DOI 101016jreactfunctpolym200706009

[17] Takagi K Miwa S Yuki Y Synthesis of poly(tri-azinylstyrene) containing nitrogen-based ligand andfunction as metal ion adsorbent and oxidation catalystReactive and Functional Polymers 66 1718ndash1724(2006)DOI 101016jreactfunctpolym200607005

[18] Ahamed M E H Mbianda X Y Mulaba-BafubiandiA F Marjanovic L Ion imprinted polymers for theselective extraction of silver(I) ions in aqueous mediaKinetic modeling and isotherm studies Reactive andFunctional Polymers 73 474ndash483 (2013)DOI 101016jreactfunctpolym201211011

[19] Wang C-C Wang C-C Adsorption characteristics ofmetal complexes by chelated copolymers with aminogroup Reactive and Functional Polymers 66 343ndash356(2006)DOI 101016jreactfunctpolym200508011

[20] Vasconcelos H L Camargo T P Gonccedilalves N SNeves A Laranjeira M C M Faacutevere V T Chitosancrosslinked with a metal complexing agent Synthesischaracterization and copper(II) ions adsorption Reac-tive and Functional Polymers 68 572ndash579 (2008)DOI 101016jreactfunctpolym200710024

[21] Huang J Zhang K The high flux poly (m-phenyleneisophthalamide) nanofiltration membrane for dyepurification and desalination Desalination 282 19ndash26 (2011)DOI 101016jdesal201109045

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

195

nology etc They are toxic to some aquatic organ-isms and are of serious health risk to human beings[18] Many physical and chemical methods havebeen used for the treatment of chemical-containingeffluents [19ndash22] Adsorption methods have beeninvariably successful to decolorize textile effluentsalthough this application can be limited by the highcost of adsorbents This work describes preparationand characterization of nanochelating resin beadsfor the removal of heavy-metal ions and azo dyesfrom water For these reasons we have focused ourattention on the development of new class function-alized adsorbents based on the copolymer poly(MMA-co-MA) To produce efficient metal-com-plexing ligand different functional groups such ascarboxylate and amine were introduced into the net-work structure of this copolymer via hydrolysisgrafting and crosslink reactions Characterization ofthe chelating resins was carried out by swellingtests FT-IR XRD AFM and SEM The results ofadsorption of Hg2+ Cd2+ and Cu2+ ions and syntheticazo dyes such as yellow 42 (AY42) red 151 (AR151)and blue 9 (MB9) by these resin beads from waterare reported here Desorption of the metal ions fromthe pre-adsorbed resins was also examined usingHCl solution

2 Experimental21 MaterialsBenzoyl peroxide (BPO) ethylenediamine (ED)diethylenetriamine (DETA) triethylenetetramine(TETA) (MMA) (MA) 2-aminopyridine (AP) tri-ethylamine (TEA) and solvents were purchasedfrom Fluka Co (Germany) Copper chloride(CuCl22H2O) mercury chloride (HgCl2) cad-mium chloride (CdCl2) and dyes such as acid yel-low 42 (AY42) acid red 151 (AR151) and mordantblue 9 (MB9) were purchased from Aldrich-SigmaCo (Germany) All the chemicals and reagents wereanalytical grade and used as received without fur-ther purification pH adjustments were performedwith HCl and NaOH solutions

22 Synthesis(a) Synthesis of Poly(MMA-co-MA) was carried

out via free-radical polymerization of (MA) and(MMA) in the presence of benzoyl peroxide(BPO) as an initiator and under argon atmos-phere according to the procedure given in liter-

ature with slight modification [23] Briefly in a250 mL three-necked round bottom flaskequipped with a magnetic stirrer a condenserand an inlet for inert gas 233 mL (0020 mol)MMA 20 g (0020 mol) MA and 50 mL THFwere placed Then the reaction mixture wasdegassed for 30 min by argon to remove oxy-gen from the solution BPO (1 wt) was addedto the reaction mixture and refluxed under theseconditions for 8 h Finally the copolymer wasprecipitated by adding the reaction mixture intothe nonsolvent of methanol and water (12 vv)The obtained white precipitate was washed thor-oughly with water and then dried under vacuumat 80degC (yield = 96)

(b) The graft copolymer (Co-g-AP) was preparedby mixing a mole ratio of 105 of poly(MMA-co-MA)AP in 50 mL THF in a 100 mL flaskequipped with a magnetic stirrer a condenserand an inlet for inert gas Then 05 mL(0004 mol) TEA was added as a catalyst andthe reaction mixture was refluxed with stirringfor 4 h The solid product was formed by addingthe reaction mixture into n-hexane After filtra-tion the solid product was washed by n-hexaneseveral times and then dried in a vacuum ovenat 80degC (yield = 95)

(c) The hydrolyzed copolymer (Co-Hyd) was pre-pared by adding 1 g poly(MMA-co-MA) and15 mL NaOH (2 M) into a 100 mL flask equippedwith a magnetic stirrer a condenser and an inletfor inert gas The mixture was stirred at roomtemperature for 7 hours until a clear homoge-neous solution was formed The hydrolyzedproduct was recovered as precipitate from basicsolution by addition of HCl (1 M) solution Theprecipitate was separated by filtration washedseveral times with distilled water and then driedunder vacuum at 80ordmC for 12 h

(d) The crosslinked resin beads (Co-g-AP1 Co-g-AP2 Co-g-AP3) were prepared in THF by thereaction between poly(MMA-co-MA) AP as agrafting agent and a crosslink agent such as EDDETA or TETA with a mole ratio of 105025respectively 05 mL (0004 mol) TEA was usedas a catalyst of the reaction The mixture wasrefluxed for 3 h under inert gas with stirringusing an ultrasonic water bath A solid precipi-tate was formed as the reaction proceeded which

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

188

was finally filtered washed several times withTHF and dried in a vacuum oven at 80degC for12 h The yields were in the range of 94ndash98

23 Adsorption studiesTo investigate the tendency of the chelating resinbeads for the removal of heavy metal ions such asCu2+ Cd2+ and Hg2+ in aqueous solutions constantweight of dried adsorbents were used in all batchexperiments Extraction of metal ions was carriedout individually by using their chloride saltsCuCl22H2O CdCl2 and HgCl2 All experimentswere performed at room temperature by using mix-ture of 50 mg beads and 50 mL metal ion solution(initial concentration 100 mgL) in separate flaskswhich were stirred magnetically for 24 h The sus-pensions were brought to the desired pH (3 6 9) byadding NaOH (01 M) and HCl (01 M) After theadsorption was complete the mixture was filteredand the residual metal-ion content in the filtrate wasdetermined by AAS The amount of metal ionadsorbed into the unit of the chelating resin ie theadsorption capacity (Q in mmolmiddotgndash1 polymer) wascalculated on the basis of Equation (1)

(1)

where C0 and CA are the concentration (mmolL) ofmetal ion in the initial solution and in the aqueousphase after adsorption respectively V is the volumeof the aqueous phase (L) and W is the weight of theadsorbent (005 g) The efficiency for ions adsorp-tion from the solution (R []) was calculated usingEquation (2)

(2)

24 Desorption behavior For the desorption experiment the chelating resinbeads which had been adsorbed with the metal ionsaccording to the procedure set-forth in the above sec-tion was used The desorption of metal ions wascarried out in 25 mL of 02 M HCl solution [24]while the mixture was stirred at room temperaturefor 1 h After filtration the metal ion concentrationin the aqueous phase was measured by AAS Thedesorption ratio (D []) was calculated by usingEquation (3)

(3)

where A is the amount of metal ions desorbed to theelution medium [mg] and B is the amount of metalions adsorbed on the resin [mg]

25 Dyes removalTo investigate the tendency of the chelating resinbeads for the removal of dyes in aqueous solutionsconstant weight of dried adsorbents were used in allbatch experiments The chemical structures of theazo dyes are shown in Figure 1 005 g of the resinbeads (Co-g-AP3 MMA-Co-MA and Co-Hyd) and10 mL aqueous solution of a dye such as AY42AR151and MB9 (initial concentration 100 mgL)were shaken in a shaker at room temperature for 12 hwithout pH adjustment The concentration of dye inthe filtrate was determined by measuring the maxi-mum absorption intensity of each dye at the corre-sponding wavelength using a UV-vis spectropho-tometer (max = 408 nm for AY42 max = 500 nm forAR151 and max =533 nm for MB9) and the follow-ing Beer-Lambert law (Equation (4))

D 3 4 5 AB ~

100

R 5C0 2 CA

C0~100

Q 51C0 2 CA 2 ~V

WQ 5

1C0 2 CA 2 ~VW

R 5C0 2 CA

C0~100

D 3 4 5 AB ~

100

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

189

Figure 1 Chemical structural of the tested dyes AY42 (a)AR151 (b) and MB9 (c)

A0 ndash A = b(C0 ndash C) (4)

where A is the absorption of dye at a given wave-length is molar absorptivity unique to each mole-cule and varying with wavelength b is the path lengththrough the solution that the light has to travel(1 cm) and C0 (100 mgL) and C is the concentra-tion of dye in the solution before and after adsorp-tion respectively The sorption percentage of thechelating resin was calculated using Equation (5)

(5)

where W is the amount of adsorbed dye and W0 theinitial amount of dye

26 MeasurementsFT-IR analysis was carried out on a Bruker Tensor27 spectrometer (Bruker Karlsruhe Germany) X-ray diffraction (XRD) patterns were obtained on aRigakuDMax-2550 powder diffractometer with ascanning speed of 5degmiddotminndash1 in the 2$ range of 10ndash70deg The surface morphology of the beads was exam-ined by using field emission scanning electron micro -scopy (FESEM) (Model Hitachi S4160) A frag-ment of the dried bead was mounted on a FESEMsample mount and was sputter coated with gold for2min and then was mounted in FESEM and scannedat the desired magnification A PHS-3C pH-meter(Shanghai Tianyou) was used for pH measurementsThe concentration of metal ions in the solution wasmeasured by use of a flame atomic absorption spec-trophotometer (AAS) (Hewlett-Packard 3510)Atomic force microscopy (AFM Easy Scan 2 FlexAFM Swiss Co) was also used to investigate thesurface phase and topography of the resin beadsbefore and after the sorption process The concen-tration of dye in the filtrate was measured using aUV-visible spectrophotometer The gel permeationchromatography (GPC) measurements were con-ducted at 30degC with a Perkin-Elmer instrumentequipped with a differential refractometer detectorThe columns used were packed with a polystyrenedivinylbenzene copolymer (PL gel MIXED-B fromPolymer Laboratories) and THF was used as fluentat a flow rate of 1 mLmin Calibration of the instru-ment was performed with monodisperse polystyrenestandards Water absorption measurements of thechelating resins were determined gravimetrically indistilled water at room temperature Briefly 02 g

dry resin beads (Co-g-AP Co-g-AP1 Co-g-AP2 Co-g-AP3 and CondashHyd) were placed in separate 50 mLvials containing distilled water for 3 days The beadswere taken out from the water at different timeswiped using a filter paper and weighed The weightdifference before and after immersion was deter-mined and used for calculation of the swelling ratio

3 Results and discussion31 Characterization and properties of the

chelating resinsThe FT-IR spectrum of poly(MMA-co-MA) Fig-ure 2a showed characteristic absorption bands ofanhydride at 1747 1809 and 1856 cmndash1 and of estergroup in the MMA repeating unit at 1724 cmndash1 Thenumber and weight average molar masses (Mn andMw) of this copolymer were determined by GPCwere 5096middot103 and 934middot103 gmol respectivelywith distribution index of 183 Earlier studies haveindicated that carboxylic acid and amide functionalgroups in polymer backbone provide more adsorp-tion sites for heavy metal ions in wastewater Inorder to obtain chelating resins as adsorbents ofheavy metals with satisfactory adsorption capacityfollowing transformations were performed (1) poly(MMA-co-MA) was hydrolyzed with NaOH (2 M)to form carboxylate ions which then neutralized byHCl to form ndashCOOH groups along the copolymerchains (2) poly(MMA-co-MA) was reacted with

R 3 4 5 WW0~100R 3 4 5 W

W0~100

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

190

Figure 2 Representative FT-IR spectra of poly(MMA-co-MA) (a) Co-g-AP3 (b) and metal-resin complexHgndash(Condashg-AP3) (c)

AP to form an alkylamide linkage and a carboxylicacid group and (3) poly(MMA-co-MA) wasreacted with AP and a crosslink agent such as EDDETA and TETA to form a network structure withmany adsorption sites for metal ions Comparisonof the FT-IR spectra of poly(MMA-co-MA) andCo-g-AP3 as shown in Figure 2a and 2b indicatesthat characteristic bands of the anhydride linkage inpoly(MMA-co-MA) at 1747 1809 and 1856 cmndash1

disappeared after reaction with TETA and the formedamide linkage (ndashCOndashNHndash) showed absorption bandat ~1676 cmndash1 To investigate the effect of chemicalreactions in the copolymer matrix the phase mor-phology was studied using SEM Figure 3andash3cshows representative SEM images of Co-g-AP Co-g-AP3 and Co-Hyd As can be seen in these figuresthe roughness of the surface and particularly the

porous surface after hydrolysis Figure 3c shouldbe considered as a factor providing chelating abilityfor the resins On that basis the adsorbents presentan adequate morphology with disordered distribu-tion of sizes which can be the main reason of theirhigh surface ability for the removal of metal ionsTo observe morphological properties such as sur-face porosity texture and roughness micrographs ofthe surface and cross section of Co-g-AP3 before andafter metal ion adsorption were registered by usingAFM Figure 3d shows smoother surface of Co-g-AP3 before metal ion adsorption while Figure 3ereveals a predominantly hill-valley-structured surfacewith irregular pores of nanoscale topography aftermetal ion adsorption The roughness can also be seenin 3D images of the surface of metal ion adsorbedsample with their histograms show size distribu-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

191

Figure 3 Representative FESEM images of Co-g-AP (a) Co-g-AP3 (b) and CondashHyd (c) AFM images of Co-g-AP3before (d) and after (e) Hg2+ ion adsorption

tions The average size for the particles of Co-g-AP3 before adsorption is in the range of 15ndash17 nmand after metal ion adsorption is in the range of 20ndash28 nm respectively The crosslinked beads are hydro -philic matrices ie hydrogels therefore they donot dissolve in aqueous media but do swell depend-ing on the degree of crosslinking and on the hydro -philicity of the matrix The equilibrium swellingratio of the resin beads are shown in Figure 4 Sev-eral possible factors are contributing in water absorp-tion of the beads such as incorporation of hydrop -hilic amino and amide groups into the polymermatrix which increases water absorption and intro-duction of hydrophobic ndashCH2ndash units into the poly-mer structure via crosslink agent such as TETA whichreduces water uptake of the resin As can be seen inFigure 4 the copolymers Co-g-AP and Co-Hydshowed the highest water absorption These twocopolymers are not crosslinked and they are opensystems with highly hydrophilic groups of car-boxylic acids The water absorption of threecrosslinked copolymers showed order of Co-g-AP3gtCo-g-AP2gtCO-g-AP1 which depended on the chem-ical structure of the curing agent (ED DETA andTETA respectively) and the network structure TheXRD patterns of all copolymers showed only a broaddiffraction hump at about 2$ = 15ndash20 indicating theamorphous nature of the prepared resin beads

32 Adsorption of heavy metal ionsIn this research the FT-IR spectroscopy was used

to monitor the structural changes take place in thechelating resins as a result of metal-ion complexa-tion Therefore the first information about the struc-tural changes such as shift or elimination of a cer-tain band present in the starting resin as well as theappearance of new bands caused by the complexa-tion of the resin with metal ions was provided by

the FT-IR spectra The bonding mode of Hg2+ tochelating resin was examined by comparing the FT-IR spectra of poly(MMAndashcondashMA) and Co-g-AP3with the spectrum of [Hgndash(Co-g-AP3)] complex Asshown in Figure 2c the FT-IR spectrum of Hg-(Co-g-AP3) is quite different from the spectrum of poly(MMA-co-MA) in Figure 2a Two strong absorptionbands at 1401 and 1544 cmndash1 are observed in thespectrum of [Hgndash(Co-g-AP3)] complex which areassigned to the symmetric (vs COOndash) and asym-metric (vas COOndash) vibration absorption of the car-boxylic groups respectively [25] The shift of FT-IR peak for the carbonyl group of carboxylate couldindicate whether the bonding between the ligandand metal ion was covalent or ionic [26] In thisstudy there is small shift towards higher frequencywhich can be taken as evidence for formation ofcovalent bond between metal ions and carbonylgroups The absorption bands characteristic of thearomatic AP in the resin matrix are observed at 1032914 767 and 703 cmndash1 which were not influenced bythe metal complexation The adsorption capacity ofthe chelating resin beads for the tested metal ions ofCu2+ Cd2+ and Hg2+ at pH 3 6 and 9 are shown inFigure 5 The results demonstrated a relativelyweak dependency of metal ions sorption on the pHvariations A relatively high adsorption of about60ndash80 was observed at various pH values for thetested metal ions by all the chelating resin beadsAdsorbents with carboxyl sulfonic and phosphonicgroups on the surface remove adsorbates throughion exchange while those containing nitrogen suchas amine hydrazine thioamide and imidazolinegroups not only chelate cationic metal ions butalso adsorb anionic adsorbates through electrostaticinteractions [27ndash29] All the prepared resins havecarboxylic acid and amine groups as potential ionexchangecomplexing units In the acidic condi-tions the degree of protonation of amine groupsaffects their ability to bind metal ions Thereforethe relatively high adsorption of metal ions in acidicconditions could be explained by the complex for-mation between M+2 and ndashCOOH groups The ndashCOOH groups are formed as a result of reactionbetween anhydride of the copolymer and amine ofthe crosslink agent and also can be due to hydroly-sis of the ester linkage in the MMA repeating unitAs can be seen in Figure 5 the dependency of adsorp-tion capacity of these resins on the pH value isrelated to the functional groups of adsorbent and

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

192

Figure 4 Water uptake of the chelating resins

type of metal ion For example all the chelatingresins adsorbed about 55 (Q = 031 mmolg) Cd2+

at pH 3 which increased to over 81 (Q =046 mmolg) at pH 9 while adsorption of Cu2+ was73 (Q = 042 mmolg) and 87 (Q = 051 mmolg)respectively at same pH values Therefore in gen-eral a high affinity was observed for adsorption ofthe tested metal ions by all the prepared resins espe-cially by Co-Hyd and Co-g-AP3 at various pH Thiscan be due to presence of different metal ion adsorp-tion sites such as carboxylate and amine groups inthe copolymer matrix The order of adsorption per-centage changed as follows Co-g-AP3Co-HydgtCo-g-AP2gtCo-g-AP1gtCo-g-AP The order of these

three kinds of metal ion chelation on mass basis forthe single component metal is Cu2+gtCd2+gtHg2+This affinity trend is presented on the mass basis[mg] metal chelation per gram resin beads and theseunits are important in quantifying respective metalcapacities in real terms Incorporation of TETA ascrosslinking agent with long alkyl chain and fouramine groups into the resin structure has signifi-cantly increased the adsorption capacity of the net-work The results show that the adsorption capacitywith Hg2+ (at pH = 6) is 714 mgg for Co-Hyd7263 mgg for Co-g-AP 73 mgg for Co-g-AP1763 mgg for Co-g-AP2 and 858 mgg for Co-g-AP3 Figure 6 illustrates the metal ions binding ontothe chelating resins Adsorbents used in heavy metalions removal are in particulate form in most of thecases In the literature different affinity sorbentswith a wide range of adsorption capacities for heavymetal ions have been reported Shreedhara-Murthyand Ryan found 5ndash27 mgg Cu(II) removal by cel-lulose dithiocarbamate resins [30] Roozemondshowed 32 mgg Cu(II) with pyrazole-containingpoly(styrene-divinyl-benzene) sorbents [31] Say etal [32] achieved 7141 4688 and 6394 mggadsorption capacities for Pb(II) Cr(III) and Cd(II)respectively with poly(HEMA-MAH) beads Karaet al [33] have prepared poly(EGDMA-VIM) beadsand found the chelation capacities of these beadswere 694 and 1148 mgg for Cd(II) and Pb(II)respectively Duran et al [34] have prepared [poly(VP-PEGMA-EGDMA)] beads and found the chela-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

193

Figure 5 Effect of the initial pH of the testing solutions onthe adsorption capacity (Q) and percentage (R[]) for the tested metal ions Initial ion concen-tration = 100 mgL sample dose = 5 mg50 mLtemperature = 25degC and contact time = 24 h

Figure 6 Illustration of metalndashchelating resin complexes ofCo-Hyd Co-g-AP and the crosslinked chelatingresin

tion capacities of these beads were 1823 16501581 and 1825 mgg for Pb(II) Cd(II) Cr(III) andCu(II) respectively

33 Desorption of metal ions from thechelating resin

The repeated use of the resins is an essential param-eter in improving process economics Desorption ofmetal ions from resinndashmetal ion complexes wascarried out by HCl (02 M ) treatment at room tem-perature and the amount of metal ions desorbed in 1hour was measured As shown in Figure 7 morethan 96 of adsorbed metal ions are recovered inthe acid leaching process indicating that chelation(ie binding of heavy metal ions with functionalgroups in resin) is completely reversible In order toobtain the reusability of the resins chelationndashelu-tion cycle was repeated successfully five times byusing the same adsorbent and the results are shownin Figure 7

34 Dyes removalThe adsorption of dyes with the prepared chelatingresin beads was carried out by using three commer-cial azo dyes containing different functional groupssuch as ndashN=Nndash chlorine oxadiazine and sulfate(Figure 1) The results for the dyes adsorption areshown in Figure 8 The order for the dyes removalby the resins is Co-g-AP3gtCo-Hydgt poly(MMA-co-MA) indicating higher capacity for the cross -linked resin in comparison with the results obtained

for the unmodified copolymer This can be due topresence of network structure with different func-tional groups in the modified resin (Co-g-AP3)which can accommodate large molecules and inter-act with the functional groups present in the dyemolecules Also the relatively high adsorption per-centage of Co-Hyd resin can be due to highly poresstructure of this resin as shown in Figure 3c

4 ConclusionsAdsorption represents a potentially cost-effectiveway of eliminating toxic heavy metals from indus-trial wastewaters Reusable polymer-based adsor-bents have been recognized as a promising class oflow-cost adsorbents for the removal of heavy-metalions from aqueous waste streams In this study thereaction of AP and different crosslink agents withpoly(MMA-co-MA) led to the synthesis of signifi-cantly capable chelating resins for the removal ofheavy metal ions such as Cu2+ Cd2+ and Hg2+ fromaqueous solution These results suggest that the pre-pared chelating resin beads are good heavy metalions adsorbents in various pH values and can havegreat potential applications in environmental pro-tection The affinity order of metal ions on a molarbasis is as Cu2+gtCd2+gtHg2+ The new adsorbentshave higher adsorption properties than other adsor-bents reported by some researchers In addition thecapacity of dyes removal of the resin beads wasinvestigated and the results showed that the adsorbeddye increased by using crosslinked resin

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

194

Figure 7 Desorption of Hg2+ ion from the chelating resinsbeads that had been preadsorbed under condi-tions given in Figure 6 as a function of submer-sion time in 25 mL of HCl (02 M) solution for1 h at 25degC

Figure 8 Dyes removal efficiency by the prepared resinbeads (005 g of the chelating resin in 10 mLaqueous solution containing a dye with initialconcentration = 100 mgL at 25degC for 12 h with-out pH adjustment)

References [1] Matsuto T Jung C H Tanaka N Material and heavy

metal balance in a recycling facility for home electri-cal appliances Waste Management 24 425ndash436 (2004)DOI 101016jwasman200312002

[2] Srivastava N K Majumder C B Novel biofiltrationmethods for the treatment of heavy metals from indus-trial wastewater Journal of Hazardous Materials 1511ndash8 (2008)DOI 101016jjhazmat200709101

[3] Vaaramaa K Lehto J Removal of metals and anionsfrom drinking water by ion exchange Desalination155 157ndash170 (2003)DOI 101016S0011-9164(03)00293-5

[4] ernaacute M Use of solvent extraction for the removal ofheavy metals from liquid wastes Environmental Mon-itoring and Assessment 34 151ndash162 (1995) DOI 101007BF00546029

[5] Hu X Li Y Wang Y Li X Li H Liu X Zhang PAdsorption kinetics thermodynamics and isotherm ofthiacalix[4]arene-loaded resin to heavy metal ionsDesalination 259 76ndash83 (2010)DOI 101016jdesal201004032

[6] Al-Rashdi B A M Johnson D J Hilal N Removalof heavy metal ions by nanofiltration Desalination315 2ndash17 (2013)DOI 101016jdesal201205022

[7] Ozaki H Sharma K Saktaywin W Performance ofan ultra-low-pressure reverse osmosis membrane(ULPROM) for separating heavy metal effects of inter-ference parameters Desalination 144 287ndash294 (2002)DOI 101016S0011-9164(02)00329-6

[8] Peterskovaacute M Valderrama C Gibert O Cortina JL Extraction of valuable metal ions (Cs Rb Li U)from reverse osmosis concentrate using selective sor-bents Desalination 286 316ndash323 (2012)DOI 101016jdesal201111042

[9] Soleimani Lashkenari M Davodi B Ghorbani MEisazadeh H Use of core-shell polyanilinepoly-styrene nanocomposite for removal of Cr(VI) HighPerformance Polymers 24 345ndash355 (2012)DOI 1011770954008311436222

[10] Li L Li Y Luo X Deng J Yang W Helical poly(N-propargylamide)s with functional catechol groupsSynthesis and adsorption of metal ions in aqueoussolution Reactive and Functional Polymers 70 938ndash943 (2010)DOI 101016jreactfunctpolym201009006

[11] Jitjaicham S Kampalanonwat P Supaphol P Metaladsorption behavior of 24-dinitrophenyl hydrazinemodified polyacrylonitrile nanofibers Express Poly-mer Letters 7 832ndash841 (2013)DOI 103144expresspolymlett201380

[12] Co$kun R Soykan C Saccedilak M Removal of someheavy metal ions from aqueous solution by adsorptionusing poly(ethylene terephthalate)-g-itaconic acidacryl -amide fiber Reactive and Functional Polymers 66599ndash608 (2006)DOI 101016jreactfunctpolym200510012

[13] Sankar R Sasidaran M Kaliyappan T Synthesischaracterization thermal and chelation properties ofnew polymeric hydrazone based on 24-dihydroxy ben-zaldehyde High Performance Polymers 23 32ndash39(2011)DOI 1011770954008310381148

[14] Sasidaran M Sankar R Kandasamy P Vijayalak-shmi S Kaliyappan T Chelating and biological prop-erties of an azo polymer resin Synthesis characteriza-tion and its application High Performance Polymers23 602ndash609 (2011)DOI 1011770954008311428531

[15] Dinu M V Dragan E S Heavy metals adsorption onsome iminodiacetate chelating resins as a function ofthe adsorption parameters Reactive and FunctionalPolymers 68 1346ndash1354 (2008)DOI 101016jreactfunctpolym200806011

[16] Vasconcelos H L Faacutevere V T Gonccedilalves N SLaranjeira M C M Chitosan modified with ReactiveBlue 2 dye on adsorption equilibrium of Cu(II) andNi(II) ions Reactive and Functional Polymers 671052ndash1060 (2007)DOI 101016jreactfunctpolym200706009

[17] Takagi K Miwa S Yuki Y Synthesis of poly(tri-azinylstyrene) containing nitrogen-based ligand andfunction as metal ion adsorbent and oxidation catalystReactive and Functional Polymers 66 1718ndash1724(2006)DOI 101016jreactfunctpolym200607005

[18] Ahamed M E H Mbianda X Y Mulaba-BafubiandiA F Marjanovic L Ion imprinted polymers for theselective extraction of silver(I) ions in aqueous mediaKinetic modeling and isotherm studies Reactive andFunctional Polymers 73 474ndash483 (2013)DOI 101016jreactfunctpolym201211011

[19] Wang C-C Wang C-C Adsorption characteristics ofmetal complexes by chelated copolymers with aminogroup Reactive and Functional Polymers 66 343ndash356(2006)DOI 101016jreactfunctpolym200508011

[20] Vasconcelos H L Camargo T P Gonccedilalves N SNeves A Laranjeira M C M Faacutevere V T Chitosancrosslinked with a metal complexing agent Synthesischaracterization and copper(II) ions adsorption Reac-tive and Functional Polymers 68 572ndash579 (2008)DOI 101016jreactfunctpolym200710024

[21] Huang J Zhang K The high flux poly (m-phenyleneisophthalamide) nanofiltration membrane for dyepurification and desalination Desalination 282 19ndash26 (2011)DOI 101016jdesal201109045

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

195

was finally filtered washed several times withTHF and dried in a vacuum oven at 80degC for12 h The yields were in the range of 94ndash98

23 Adsorption studiesTo investigate the tendency of the chelating resinbeads for the removal of heavy metal ions such asCu2+ Cd2+ and Hg2+ in aqueous solutions constantweight of dried adsorbents were used in all batchexperiments Extraction of metal ions was carriedout individually by using their chloride saltsCuCl22H2O CdCl2 and HgCl2 All experimentswere performed at room temperature by using mix-ture of 50 mg beads and 50 mL metal ion solution(initial concentration 100 mgL) in separate flaskswhich were stirred magnetically for 24 h The sus-pensions were brought to the desired pH (3 6 9) byadding NaOH (01 M) and HCl (01 M) After theadsorption was complete the mixture was filteredand the residual metal-ion content in the filtrate wasdetermined by AAS The amount of metal ionadsorbed into the unit of the chelating resin ie theadsorption capacity (Q in mmolmiddotgndash1 polymer) wascalculated on the basis of Equation (1)

(1)

where C0 and CA are the concentration (mmolL) ofmetal ion in the initial solution and in the aqueousphase after adsorption respectively V is the volumeof the aqueous phase (L) and W is the weight of theadsorbent (005 g) The efficiency for ions adsorp-tion from the solution (R []) was calculated usingEquation (2)

(2)

24 Desorption behavior For the desorption experiment the chelating resinbeads which had been adsorbed with the metal ionsaccording to the procedure set-forth in the above sec-tion was used The desorption of metal ions wascarried out in 25 mL of 02 M HCl solution [24]while the mixture was stirred at room temperaturefor 1 h After filtration the metal ion concentrationin the aqueous phase was measured by AAS Thedesorption ratio (D []) was calculated by usingEquation (3)

(3)

where A is the amount of metal ions desorbed to theelution medium [mg] and B is the amount of metalions adsorbed on the resin [mg]

25 Dyes removalTo investigate the tendency of the chelating resinbeads for the removal of dyes in aqueous solutionsconstant weight of dried adsorbents were used in allbatch experiments The chemical structures of theazo dyes are shown in Figure 1 005 g of the resinbeads (Co-g-AP3 MMA-Co-MA and Co-Hyd) and10 mL aqueous solution of a dye such as AY42AR151and MB9 (initial concentration 100 mgL)were shaken in a shaker at room temperature for 12 hwithout pH adjustment The concentration of dye inthe filtrate was determined by measuring the maxi-mum absorption intensity of each dye at the corre-sponding wavelength using a UV-vis spectropho-tometer (max = 408 nm for AY42 max = 500 nm forAR151 and max =533 nm for MB9) and the follow-ing Beer-Lambert law (Equation (4))

D 3 4 5 AB ~

100

R 5C0 2 CA

C0~100

Q 51C0 2 CA 2 ~V

WQ 5

1C0 2 CA 2 ~VW

R 5C0 2 CA

C0~100

D 3 4 5 AB ~

100

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

189

Figure 1 Chemical structural of the tested dyes AY42 (a)AR151 (b) and MB9 (c)

A0 ndash A = b(C0 ndash C) (4)

where A is the absorption of dye at a given wave-length is molar absorptivity unique to each mole-cule and varying with wavelength b is the path lengththrough the solution that the light has to travel(1 cm) and C0 (100 mgL) and C is the concentra-tion of dye in the solution before and after adsorp-tion respectively The sorption percentage of thechelating resin was calculated using Equation (5)

(5)

where W is the amount of adsorbed dye and W0 theinitial amount of dye

26 MeasurementsFT-IR analysis was carried out on a Bruker Tensor27 spectrometer (Bruker Karlsruhe Germany) X-ray diffraction (XRD) patterns were obtained on aRigakuDMax-2550 powder diffractometer with ascanning speed of 5degmiddotminndash1 in the 2$ range of 10ndash70deg The surface morphology of the beads was exam-ined by using field emission scanning electron micro -scopy (FESEM) (Model Hitachi S4160) A frag-ment of the dried bead was mounted on a FESEMsample mount and was sputter coated with gold for2min and then was mounted in FESEM and scannedat the desired magnification A PHS-3C pH-meter(Shanghai Tianyou) was used for pH measurementsThe concentration of metal ions in the solution wasmeasured by use of a flame atomic absorption spec-trophotometer (AAS) (Hewlett-Packard 3510)Atomic force microscopy (AFM Easy Scan 2 FlexAFM Swiss Co) was also used to investigate thesurface phase and topography of the resin beadsbefore and after the sorption process The concen-tration of dye in the filtrate was measured using aUV-visible spectrophotometer The gel permeationchromatography (GPC) measurements were con-ducted at 30degC with a Perkin-Elmer instrumentequipped with a differential refractometer detectorThe columns used were packed with a polystyrenedivinylbenzene copolymer (PL gel MIXED-B fromPolymer Laboratories) and THF was used as fluentat a flow rate of 1 mLmin Calibration of the instru-ment was performed with monodisperse polystyrenestandards Water absorption measurements of thechelating resins were determined gravimetrically indistilled water at room temperature Briefly 02 g

dry resin beads (Co-g-AP Co-g-AP1 Co-g-AP2 Co-g-AP3 and CondashHyd) were placed in separate 50 mLvials containing distilled water for 3 days The beadswere taken out from the water at different timeswiped using a filter paper and weighed The weightdifference before and after immersion was deter-mined and used for calculation of the swelling ratio

3 Results and discussion31 Characterization and properties of the

chelating resinsThe FT-IR spectrum of poly(MMA-co-MA) Fig-ure 2a showed characteristic absorption bands ofanhydride at 1747 1809 and 1856 cmndash1 and of estergroup in the MMA repeating unit at 1724 cmndash1 Thenumber and weight average molar masses (Mn andMw) of this copolymer were determined by GPCwere 5096middot103 and 934middot103 gmol respectivelywith distribution index of 183 Earlier studies haveindicated that carboxylic acid and amide functionalgroups in polymer backbone provide more adsorp-tion sites for heavy metal ions in wastewater Inorder to obtain chelating resins as adsorbents ofheavy metals with satisfactory adsorption capacityfollowing transformations were performed (1) poly(MMA-co-MA) was hydrolyzed with NaOH (2 M)to form carboxylate ions which then neutralized byHCl to form ndashCOOH groups along the copolymerchains (2) poly(MMA-co-MA) was reacted with

R 3 4 5 WW0~100R 3 4 5 W

W0~100

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

190

Figure 2 Representative FT-IR spectra of poly(MMA-co-MA) (a) Co-g-AP3 (b) and metal-resin complexHgndash(Condashg-AP3) (c)

AP to form an alkylamide linkage and a carboxylicacid group and (3) poly(MMA-co-MA) wasreacted with AP and a crosslink agent such as EDDETA and TETA to form a network structure withmany adsorption sites for metal ions Comparisonof the FT-IR spectra of poly(MMA-co-MA) andCo-g-AP3 as shown in Figure 2a and 2b indicatesthat characteristic bands of the anhydride linkage inpoly(MMA-co-MA) at 1747 1809 and 1856 cmndash1

disappeared after reaction with TETA and the formedamide linkage (ndashCOndashNHndash) showed absorption bandat ~1676 cmndash1 To investigate the effect of chemicalreactions in the copolymer matrix the phase mor-phology was studied using SEM Figure 3andash3cshows representative SEM images of Co-g-AP Co-g-AP3 and Co-Hyd As can be seen in these figuresthe roughness of the surface and particularly the

porous surface after hydrolysis Figure 3c shouldbe considered as a factor providing chelating abilityfor the resins On that basis the adsorbents presentan adequate morphology with disordered distribu-tion of sizes which can be the main reason of theirhigh surface ability for the removal of metal ionsTo observe morphological properties such as sur-face porosity texture and roughness micrographs ofthe surface and cross section of Co-g-AP3 before andafter metal ion adsorption were registered by usingAFM Figure 3d shows smoother surface of Co-g-AP3 before metal ion adsorption while Figure 3ereveals a predominantly hill-valley-structured surfacewith irregular pores of nanoscale topography aftermetal ion adsorption The roughness can also be seenin 3D images of the surface of metal ion adsorbedsample with their histograms show size distribu-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

191

Figure 3 Representative FESEM images of Co-g-AP (a) Co-g-AP3 (b) and CondashHyd (c) AFM images of Co-g-AP3before (d) and after (e) Hg2+ ion adsorption

tions The average size for the particles of Co-g-AP3 before adsorption is in the range of 15ndash17 nmand after metal ion adsorption is in the range of 20ndash28 nm respectively The crosslinked beads are hydro -philic matrices ie hydrogels therefore they donot dissolve in aqueous media but do swell depend-ing on the degree of crosslinking and on the hydro -philicity of the matrix The equilibrium swellingratio of the resin beads are shown in Figure 4 Sev-eral possible factors are contributing in water absorp-tion of the beads such as incorporation of hydrop -hilic amino and amide groups into the polymermatrix which increases water absorption and intro-duction of hydrophobic ndashCH2ndash units into the poly-mer structure via crosslink agent such as TETA whichreduces water uptake of the resin As can be seen inFigure 4 the copolymers Co-g-AP and Co-Hydshowed the highest water absorption These twocopolymers are not crosslinked and they are opensystems with highly hydrophilic groups of car-boxylic acids The water absorption of threecrosslinked copolymers showed order of Co-g-AP3gtCo-g-AP2gtCO-g-AP1 which depended on the chem-ical structure of the curing agent (ED DETA andTETA respectively) and the network structure TheXRD patterns of all copolymers showed only a broaddiffraction hump at about 2$ = 15ndash20 indicating theamorphous nature of the prepared resin beads

32 Adsorption of heavy metal ionsIn this research the FT-IR spectroscopy was used

to monitor the structural changes take place in thechelating resins as a result of metal-ion complexa-tion Therefore the first information about the struc-tural changes such as shift or elimination of a cer-tain band present in the starting resin as well as theappearance of new bands caused by the complexa-tion of the resin with metal ions was provided by

the FT-IR spectra The bonding mode of Hg2+ tochelating resin was examined by comparing the FT-IR spectra of poly(MMAndashcondashMA) and Co-g-AP3with the spectrum of [Hgndash(Co-g-AP3)] complex Asshown in Figure 2c the FT-IR spectrum of Hg-(Co-g-AP3) is quite different from the spectrum of poly(MMA-co-MA) in Figure 2a Two strong absorptionbands at 1401 and 1544 cmndash1 are observed in thespectrum of [Hgndash(Co-g-AP3)] complex which areassigned to the symmetric (vs COOndash) and asym-metric (vas COOndash) vibration absorption of the car-boxylic groups respectively [25] The shift of FT-IR peak for the carbonyl group of carboxylate couldindicate whether the bonding between the ligandand metal ion was covalent or ionic [26] In thisstudy there is small shift towards higher frequencywhich can be taken as evidence for formation ofcovalent bond between metal ions and carbonylgroups The absorption bands characteristic of thearomatic AP in the resin matrix are observed at 1032914 767 and 703 cmndash1 which were not influenced bythe metal complexation The adsorption capacity ofthe chelating resin beads for the tested metal ions ofCu2+ Cd2+ and Hg2+ at pH 3 6 and 9 are shown inFigure 5 The results demonstrated a relativelyweak dependency of metal ions sorption on the pHvariations A relatively high adsorption of about60ndash80 was observed at various pH values for thetested metal ions by all the chelating resin beadsAdsorbents with carboxyl sulfonic and phosphonicgroups on the surface remove adsorbates throughion exchange while those containing nitrogen suchas amine hydrazine thioamide and imidazolinegroups not only chelate cationic metal ions butalso adsorb anionic adsorbates through electrostaticinteractions [27ndash29] All the prepared resins havecarboxylic acid and amine groups as potential ionexchangecomplexing units In the acidic condi-tions the degree of protonation of amine groupsaffects their ability to bind metal ions Thereforethe relatively high adsorption of metal ions in acidicconditions could be explained by the complex for-mation between M+2 and ndashCOOH groups The ndashCOOH groups are formed as a result of reactionbetween anhydride of the copolymer and amine ofthe crosslink agent and also can be due to hydroly-sis of the ester linkage in the MMA repeating unitAs can be seen in Figure 5 the dependency of adsorp-tion capacity of these resins on the pH value isrelated to the functional groups of adsorbent and

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

192

Figure 4 Water uptake of the chelating resins

type of metal ion For example all the chelatingresins adsorbed about 55 (Q = 031 mmolg) Cd2+

at pH 3 which increased to over 81 (Q =046 mmolg) at pH 9 while adsorption of Cu2+ was73 (Q = 042 mmolg) and 87 (Q = 051 mmolg)respectively at same pH values Therefore in gen-eral a high affinity was observed for adsorption ofthe tested metal ions by all the prepared resins espe-cially by Co-Hyd and Co-g-AP3 at various pH Thiscan be due to presence of different metal ion adsorp-tion sites such as carboxylate and amine groups inthe copolymer matrix The order of adsorption per-centage changed as follows Co-g-AP3Co-HydgtCo-g-AP2gtCo-g-AP1gtCo-g-AP The order of these

three kinds of metal ion chelation on mass basis forthe single component metal is Cu2+gtCd2+gtHg2+This affinity trend is presented on the mass basis[mg] metal chelation per gram resin beads and theseunits are important in quantifying respective metalcapacities in real terms Incorporation of TETA ascrosslinking agent with long alkyl chain and fouramine groups into the resin structure has signifi-cantly increased the adsorption capacity of the net-work The results show that the adsorption capacitywith Hg2+ (at pH = 6) is 714 mgg for Co-Hyd7263 mgg for Co-g-AP 73 mgg for Co-g-AP1763 mgg for Co-g-AP2 and 858 mgg for Co-g-AP3 Figure 6 illustrates the metal ions binding ontothe chelating resins Adsorbents used in heavy metalions removal are in particulate form in most of thecases In the literature different affinity sorbentswith a wide range of adsorption capacities for heavymetal ions have been reported Shreedhara-Murthyand Ryan found 5ndash27 mgg Cu(II) removal by cel-lulose dithiocarbamate resins [30] Roozemondshowed 32 mgg Cu(II) with pyrazole-containingpoly(styrene-divinyl-benzene) sorbents [31] Say etal [32] achieved 7141 4688 and 6394 mggadsorption capacities for Pb(II) Cr(III) and Cd(II)respectively with poly(HEMA-MAH) beads Karaet al [33] have prepared poly(EGDMA-VIM) beadsand found the chelation capacities of these beadswere 694 and 1148 mgg for Cd(II) and Pb(II)respectively Duran et al [34] have prepared [poly(VP-PEGMA-EGDMA)] beads and found the chela-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

193

Figure 5 Effect of the initial pH of the testing solutions onthe adsorption capacity (Q) and percentage (R[]) for the tested metal ions Initial ion concen-tration = 100 mgL sample dose = 5 mg50 mLtemperature = 25degC and contact time = 24 h

Figure 6 Illustration of metalndashchelating resin complexes ofCo-Hyd Co-g-AP and the crosslinked chelatingresin

tion capacities of these beads were 1823 16501581 and 1825 mgg for Pb(II) Cd(II) Cr(III) andCu(II) respectively

33 Desorption of metal ions from thechelating resin

The repeated use of the resins is an essential param-eter in improving process economics Desorption ofmetal ions from resinndashmetal ion complexes wascarried out by HCl (02 M ) treatment at room tem-perature and the amount of metal ions desorbed in 1hour was measured As shown in Figure 7 morethan 96 of adsorbed metal ions are recovered inthe acid leaching process indicating that chelation(ie binding of heavy metal ions with functionalgroups in resin) is completely reversible In order toobtain the reusability of the resins chelationndashelu-tion cycle was repeated successfully five times byusing the same adsorbent and the results are shownin Figure 7

34 Dyes removalThe adsorption of dyes with the prepared chelatingresin beads was carried out by using three commer-cial azo dyes containing different functional groupssuch as ndashN=Nndash chlorine oxadiazine and sulfate(Figure 1) The results for the dyes adsorption areshown in Figure 8 The order for the dyes removalby the resins is Co-g-AP3gtCo-Hydgt poly(MMA-co-MA) indicating higher capacity for the cross -linked resin in comparison with the results obtained

for the unmodified copolymer This can be due topresence of network structure with different func-tional groups in the modified resin (Co-g-AP3)which can accommodate large molecules and inter-act with the functional groups present in the dyemolecules Also the relatively high adsorption per-centage of Co-Hyd resin can be due to highly poresstructure of this resin as shown in Figure 3c

4 ConclusionsAdsorption represents a potentially cost-effectiveway of eliminating toxic heavy metals from indus-trial wastewaters Reusable polymer-based adsor-bents have been recognized as a promising class oflow-cost adsorbents for the removal of heavy-metalions from aqueous waste streams In this study thereaction of AP and different crosslink agents withpoly(MMA-co-MA) led to the synthesis of signifi-cantly capable chelating resins for the removal ofheavy metal ions such as Cu2+ Cd2+ and Hg2+ fromaqueous solution These results suggest that the pre-pared chelating resin beads are good heavy metalions adsorbents in various pH values and can havegreat potential applications in environmental pro-tection The affinity order of metal ions on a molarbasis is as Cu2+gtCd2+gtHg2+ The new adsorbentshave higher adsorption properties than other adsor-bents reported by some researchers In addition thecapacity of dyes removal of the resin beads wasinvestigated and the results showed that the adsorbeddye increased by using crosslinked resin

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

194

Figure 7 Desorption of Hg2+ ion from the chelating resinsbeads that had been preadsorbed under condi-tions given in Figure 6 as a function of submer-sion time in 25 mL of HCl (02 M) solution for1 h at 25degC

Figure 8 Dyes removal efficiency by the prepared resinbeads (005 g of the chelating resin in 10 mLaqueous solution containing a dye with initialconcentration = 100 mgL at 25degC for 12 h with-out pH adjustment)

References [1] Matsuto T Jung C H Tanaka N Material and heavy

metal balance in a recycling facility for home electri-cal appliances Waste Management 24 425ndash436 (2004)DOI 101016jwasman200312002

[2] Srivastava N K Majumder C B Novel biofiltrationmethods for the treatment of heavy metals from indus-trial wastewater Journal of Hazardous Materials 1511ndash8 (2008)DOI 101016jjhazmat200709101

[3] Vaaramaa K Lehto J Removal of metals and anionsfrom drinking water by ion exchange Desalination155 157ndash170 (2003)DOI 101016S0011-9164(03)00293-5

[4] ernaacute M Use of solvent extraction for the removal ofheavy metals from liquid wastes Environmental Mon-itoring and Assessment 34 151ndash162 (1995) DOI 101007BF00546029

[5] Hu X Li Y Wang Y Li X Li H Liu X Zhang PAdsorption kinetics thermodynamics and isotherm ofthiacalix[4]arene-loaded resin to heavy metal ionsDesalination 259 76ndash83 (2010)DOI 101016jdesal201004032

[6] Al-Rashdi B A M Johnson D J Hilal N Removalof heavy metal ions by nanofiltration Desalination315 2ndash17 (2013)DOI 101016jdesal201205022

[7] Ozaki H Sharma K Saktaywin W Performance ofan ultra-low-pressure reverse osmosis membrane(ULPROM) for separating heavy metal effects of inter-ference parameters Desalination 144 287ndash294 (2002)DOI 101016S0011-9164(02)00329-6

[8] Peterskovaacute M Valderrama C Gibert O Cortina JL Extraction of valuable metal ions (Cs Rb Li U)from reverse osmosis concentrate using selective sor-bents Desalination 286 316ndash323 (2012)DOI 101016jdesal201111042

[9] Soleimani Lashkenari M Davodi B Ghorbani MEisazadeh H Use of core-shell polyanilinepoly-styrene nanocomposite for removal of Cr(VI) HighPerformance Polymers 24 345ndash355 (2012)DOI 1011770954008311436222

[10] Li L Li Y Luo X Deng J Yang W Helical poly(N-propargylamide)s with functional catechol groupsSynthesis and adsorption of metal ions in aqueoussolution Reactive and Functional Polymers 70 938ndash943 (2010)DOI 101016jreactfunctpolym201009006

[11] Jitjaicham S Kampalanonwat P Supaphol P Metaladsorption behavior of 24-dinitrophenyl hydrazinemodified polyacrylonitrile nanofibers Express Poly-mer Letters 7 832ndash841 (2013)DOI 103144expresspolymlett201380

[12] Co$kun R Soykan C Saccedilak M Removal of someheavy metal ions from aqueous solution by adsorptionusing poly(ethylene terephthalate)-g-itaconic acidacryl -amide fiber Reactive and Functional Polymers 66599ndash608 (2006)DOI 101016jreactfunctpolym200510012

[13] Sankar R Sasidaran M Kaliyappan T Synthesischaracterization thermal and chelation properties ofnew polymeric hydrazone based on 24-dihydroxy ben-zaldehyde High Performance Polymers 23 32ndash39(2011)DOI 1011770954008310381148

[14] Sasidaran M Sankar R Kandasamy P Vijayalak-shmi S Kaliyappan T Chelating and biological prop-erties of an azo polymer resin Synthesis characteriza-tion and its application High Performance Polymers23 602ndash609 (2011)DOI 1011770954008311428531

[15] Dinu M V Dragan E S Heavy metals adsorption onsome iminodiacetate chelating resins as a function ofthe adsorption parameters Reactive and FunctionalPolymers 68 1346ndash1354 (2008)DOI 101016jreactfunctpolym200806011

[16] Vasconcelos H L Faacutevere V T Gonccedilalves N SLaranjeira M C M Chitosan modified with ReactiveBlue 2 dye on adsorption equilibrium of Cu(II) andNi(II) ions Reactive and Functional Polymers 671052ndash1060 (2007)DOI 101016jreactfunctpolym200706009

[17] Takagi K Miwa S Yuki Y Synthesis of poly(tri-azinylstyrene) containing nitrogen-based ligand andfunction as metal ion adsorbent and oxidation catalystReactive and Functional Polymers 66 1718ndash1724(2006)DOI 101016jreactfunctpolym200607005

[18] Ahamed M E H Mbianda X Y Mulaba-BafubiandiA F Marjanovic L Ion imprinted polymers for theselective extraction of silver(I) ions in aqueous mediaKinetic modeling and isotherm studies Reactive andFunctional Polymers 73 474ndash483 (2013)DOI 101016jreactfunctpolym201211011

[19] Wang C-C Wang C-C Adsorption characteristics ofmetal complexes by chelated copolymers with aminogroup Reactive and Functional Polymers 66 343ndash356(2006)DOI 101016jreactfunctpolym200508011

[20] Vasconcelos H L Camargo T P Gonccedilalves N SNeves A Laranjeira M C M Faacutevere V T Chitosancrosslinked with a metal complexing agent Synthesischaracterization and copper(II) ions adsorption Reac-tive and Functional Polymers 68 572ndash579 (2008)DOI 101016jreactfunctpolym200710024

[21] Huang J Zhang K The high flux poly (m-phenyleneisophthalamide) nanofiltration membrane for dyepurification and desalination Desalination 282 19ndash26 (2011)DOI 101016jdesal201109045

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

195

A0 ndash A = b(C0 ndash C) (4)

where A is the absorption of dye at a given wave-length is molar absorptivity unique to each mole-cule and varying with wavelength b is the path lengththrough the solution that the light has to travel(1 cm) and C0 (100 mgL) and C is the concentra-tion of dye in the solution before and after adsorp-tion respectively The sorption percentage of thechelating resin was calculated using Equation (5)

(5)

where W is the amount of adsorbed dye and W0 theinitial amount of dye

26 MeasurementsFT-IR analysis was carried out on a Bruker Tensor27 spectrometer (Bruker Karlsruhe Germany) X-ray diffraction (XRD) patterns were obtained on aRigakuDMax-2550 powder diffractometer with ascanning speed of 5degmiddotminndash1 in the 2$ range of 10ndash70deg The surface morphology of the beads was exam-ined by using field emission scanning electron micro -scopy (FESEM) (Model Hitachi S4160) A frag-ment of the dried bead was mounted on a FESEMsample mount and was sputter coated with gold for2min and then was mounted in FESEM and scannedat the desired magnification A PHS-3C pH-meter(Shanghai Tianyou) was used for pH measurementsThe concentration of metal ions in the solution wasmeasured by use of a flame atomic absorption spec-trophotometer (AAS) (Hewlett-Packard 3510)Atomic force microscopy (AFM Easy Scan 2 FlexAFM Swiss Co) was also used to investigate thesurface phase and topography of the resin beadsbefore and after the sorption process The concen-tration of dye in the filtrate was measured using aUV-visible spectrophotometer The gel permeationchromatography (GPC) measurements were con-ducted at 30degC with a Perkin-Elmer instrumentequipped with a differential refractometer detectorThe columns used were packed with a polystyrenedivinylbenzene copolymer (PL gel MIXED-B fromPolymer Laboratories) and THF was used as fluentat a flow rate of 1 mLmin Calibration of the instru-ment was performed with monodisperse polystyrenestandards Water absorption measurements of thechelating resins were determined gravimetrically indistilled water at room temperature Briefly 02 g

dry resin beads (Co-g-AP Co-g-AP1 Co-g-AP2 Co-g-AP3 and CondashHyd) were placed in separate 50 mLvials containing distilled water for 3 days The beadswere taken out from the water at different timeswiped using a filter paper and weighed The weightdifference before and after immersion was deter-mined and used for calculation of the swelling ratio

3 Results and discussion31 Characterization and properties of the

chelating resinsThe FT-IR spectrum of poly(MMA-co-MA) Fig-ure 2a showed characteristic absorption bands ofanhydride at 1747 1809 and 1856 cmndash1 and of estergroup in the MMA repeating unit at 1724 cmndash1 Thenumber and weight average molar masses (Mn andMw) of this copolymer were determined by GPCwere 5096middot103 and 934middot103 gmol respectivelywith distribution index of 183 Earlier studies haveindicated that carboxylic acid and amide functionalgroups in polymer backbone provide more adsorp-tion sites for heavy metal ions in wastewater Inorder to obtain chelating resins as adsorbents ofheavy metals with satisfactory adsorption capacityfollowing transformations were performed (1) poly(MMA-co-MA) was hydrolyzed with NaOH (2 M)to form carboxylate ions which then neutralized byHCl to form ndashCOOH groups along the copolymerchains (2) poly(MMA-co-MA) was reacted with

R 3 4 5 WW0~100R 3 4 5 W

W0~100

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

190

Figure 2 Representative FT-IR spectra of poly(MMA-co-MA) (a) Co-g-AP3 (b) and metal-resin complexHgndash(Condashg-AP3) (c)

AP to form an alkylamide linkage and a carboxylicacid group and (3) poly(MMA-co-MA) wasreacted with AP and a crosslink agent such as EDDETA and TETA to form a network structure withmany adsorption sites for metal ions Comparisonof the FT-IR spectra of poly(MMA-co-MA) andCo-g-AP3 as shown in Figure 2a and 2b indicatesthat characteristic bands of the anhydride linkage inpoly(MMA-co-MA) at 1747 1809 and 1856 cmndash1

disappeared after reaction with TETA and the formedamide linkage (ndashCOndashNHndash) showed absorption bandat ~1676 cmndash1 To investigate the effect of chemicalreactions in the copolymer matrix the phase mor-phology was studied using SEM Figure 3andash3cshows representative SEM images of Co-g-AP Co-g-AP3 and Co-Hyd As can be seen in these figuresthe roughness of the surface and particularly the

porous surface after hydrolysis Figure 3c shouldbe considered as a factor providing chelating abilityfor the resins On that basis the adsorbents presentan adequate morphology with disordered distribu-tion of sizes which can be the main reason of theirhigh surface ability for the removal of metal ionsTo observe morphological properties such as sur-face porosity texture and roughness micrographs ofthe surface and cross section of Co-g-AP3 before andafter metal ion adsorption were registered by usingAFM Figure 3d shows smoother surface of Co-g-AP3 before metal ion adsorption while Figure 3ereveals a predominantly hill-valley-structured surfacewith irregular pores of nanoscale topography aftermetal ion adsorption The roughness can also be seenin 3D images of the surface of metal ion adsorbedsample with their histograms show size distribu-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

191

Figure 3 Representative FESEM images of Co-g-AP (a) Co-g-AP3 (b) and CondashHyd (c) AFM images of Co-g-AP3before (d) and after (e) Hg2+ ion adsorption

tions The average size for the particles of Co-g-AP3 before adsorption is in the range of 15ndash17 nmand after metal ion adsorption is in the range of 20ndash28 nm respectively The crosslinked beads are hydro -philic matrices ie hydrogels therefore they donot dissolve in aqueous media but do swell depend-ing on the degree of crosslinking and on the hydro -philicity of the matrix The equilibrium swellingratio of the resin beads are shown in Figure 4 Sev-eral possible factors are contributing in water absorp-tion of the beads such as incorporation of hydrop -hilic amino and amide groups into the polymermatrix which increases water absorption and intro-duction of hydrophobic ndashCH2ndash units into the poly-mer structure via crosslink agent such as TETA whichreduces water uptake of the resin As can be seen inFigure 4 the copolymers Co-g-AP and Co-Hydshowed the highest water absorption These twocopolymers are not crosslinked and they are opensystems with highly hydrophilic groups of car-boxylic acids The water absorption of threecrosslinked copolymers showed order of Co-g-AP3gtCo-g-AP2gtCO-g-AP1 which depended on the chem-ical structure of the curing agent (ED DETA andTETA respectively) and the network structure TheXRD patterns of all copolymers showed only a broaddiffraction hump at about 2$ = 15ndash20 indicating theamorphous nature of the prepared resin beads

32 Adsorption of heavy metal ionsIn this research the FT-IR spectroscopy was used

to monitor the structural changes take place in thechelating resins as a result of metal-ion complexa-tion Therefore the first information about the struc-tural changes such as shift or elimination of a cer-tain band present in the starting resin as well as theappearance of new bands caused by the complexa-tion of the resin with metal ions was provided by

the FT-IR spectra The bonding mode of Hg2+ tochelating resin was examined by comparing the FT-IR spectra of poly(MMAndashcondashMA) and Co-g-AP3with the spectrum of [Hgndash(Co-g-AP3)] complex Asshown in Figure 2c the FT-IR spectrum of Hg-(Co-g-AP3) is quite different from the spectrum of poly(MMA-co-MA) in Figure 2a Two strong absorptionbands at 1401 and 1544 cmndash1 are observed in thespectrum of [Hgndash(Co-g-AP3)] complex which areassigned to the symmetric (vs COOndash) and asym-metric (vas COOndash) vibration absorption of the car-boxylic groups respectively [25] The shift of FT-IR peak for the carbonyl group of carboxylate couldindicate whether the bonding between the ligandand metal ion was covalent or ionic [26] In thisstudy there is small shift towards higher frequencywhich can be taken as evidence for formation ofcovalent bond between metal ions and carbonylgroups The absorption bands characteristic of thearomatic AP in the resin matrix are observed at 1032914 767 and 703 cmndash1 which were not influenced bythe metal complexation The adsorption capacity ofthe chelating resin beads for the tested metal ions ofCu2+ Cd2+ and Hg2+ at pH 3 6 and 9 are shown inFigure 5 The results demonstrated a relativelyweak dependency of metal ions sorption on the pHvariations A relatively high adsorption of about60ndash80 was observed at various pH values for thetested metal ions by all the chelating resin beadsAdsorbents with carboxyl sulfonic and phosphonicgroups on the surface remove adsorbates throughion exchange while those containing nitrogen suchas amine hydrazine thioamide and imidazolinegroups not only chelate cationic metal ions butalso adsorb anionic adsorbates through electrostaticinteractions [27ndash29] All the prepared resins havecarboxylic acid and amine groups as potential ionexchangecomplexing units In the acidic condi-tions the degree of protonation of amine groupsaffects their ability to bind metal ions Thereforethe relatively high adsorption of metal ions in acidicconditions could be explained by the complex for-mation between M+2 and ndashCOOH groups The ndashCOOH groups are formed as a result of reactionbetween anhydride of the copolymer and amine ofthe crosslink agent and also can be due to hydroly-sis of the ester linkage in the MMA repeating unitAs can be seen in Figure 5 the dependency of adsorp-tion capacity of these resins on the pH value isrelated to the functional groups of adsorbent and

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

192

Figure 4 Water uptake of the chelating resins

type of metal ion For example all the chelatingresins adsorbed about 55 (Q = 031 mmolg) Cd2+

at pH 3 which increased to over 81 (Q =046 mmolg) at pH 9 while adsorption of Cu2+ was73 (Q = 042 mmolg) and 87 (Q = 051 mmolg)respectively at same pH values Therefore in gen-eral a high affinity was observed for adsorption ofthe tested metal ions by all the prepared resins espe-cially by Co-Hyd and Co-g-AP3 at various pH Thiscan be due to presence of different metal ion adsorp-tion sites such as carboxylate and amine groups inthe copolymer matrix The order of adsorption per-centage changed as follows Co-g-AP3Co-HydgtCo-g-AP2gtCo-g-AP1gtCo-g-AP The order of these

three kinds of metal ion chelation on mass basis forthe single component metal is Cu2+gtCd2+gtHg2+This affinity trend is presented on the mass basis[mg] metal chelation per gram resin beads and theseunits are important in quantifying respective metalcapacities in real terms Incorporation of TETA ascrosslinking agent with long alkyl chain and fouramine groups into the resin structure has signifi-cantly increased the adsorption capacity of the net-work The results show that the adsorption capacitywith Hg2+ (at pH = 6) is 714 mgg for Co-Hyd7263 mgg for Co-g-AP 73 mgg for Co-g-AP1763 mgg for Co-g-AP2 and 858 mgg for Co-g-AP3 Figure 6 illustrates the metal ions binding ontothe chelating resins Adsorbents used in heavy metalions removal are in particulate form in most of thecases In the literature different affinity sorbentswith a wide range of adsorption capacities for heavymetal ions have been reported Shreedhara-Murthyand Ryan found 5ndash27 mgg Cu(II) removal by cel-lulose dithiocarbamate resins [30] Roozemondshowed 32 mgg Cu(II) with pyrazole-containingpoly(styrene-divinyl-benzene) sorbents [31] Say etal [32] achieved 7141 4688 and 6394 mggadsorption capacities for Pb(II) Cr(III) and Cd(II)respectively with poly(HEMA-MAH) beads Karaet al [33] have prepared poly(EGDMA-VIM) beadsand found the chelation capacities of these beadswere 694 and 1148 mgg for Cd(II) and Pb(II)respectively Duran et al [34] have prepared [poly(VP-PEGMA-EGDMA)] beads and found the chela-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

193

Figure 5 Effect of the initial pH of the testing solutions onthe adsorption capacity (Q) and percentage (R[]) for the tested metal ions Initial ion concen-tration = 100 mgL sample dose = 5 mg50 mLtemperature = 25degC and contact time = 24 h

Figure 6 Illustration of metalndashchelating resin complexes ofCo-Hyd Co-g-AP and the crosslinked chelatingresin

tion capacities of these beads were 1823 16501581 and 1825 mgg for Pb(II) Cd(II) Cr(III) andCu(II) respectively

33 Desorption of metal ions from thechelating resin

The repeated use of the resins is an essential param-eter in improving process economics Desorption ofmetal ions from resinndashmetal ion complexes wascarried out by HCl (02 M ) treatment at room tem-perature and the amount of metal ions desorbed in 1hour was measured As shown in Figure 7 morethan 96 of adsorbed metal ions are recovered inthe acid leaching process indicating that chelation(ie binding of heavy metal ions with functionalgroups in resin) is completely reversible In order toobtain the reusability of the resins chelationndashelu-tion cycle was repeated successfully five times byusing the same adsorbent and the results are shownin Figure 7

34 Dyes removalThe adsorption of dyes with the prepared chelatingresin beads was carried out by using three commer-cial azo dyes containing different functional groupssuch as ndashN=Nndash chlorine oxadiazine and sulfate(Figure 1) The results for the dyes adsorption areshown in Figure 8 The order for the dyes removalby the resins is Co-g-AP3gtCo-Hydgt poly(MMA-co-MA) indicating higher capacity for the cross -linked resin in comparison with the results obtained

for the unmodified copolymer This can be due topresence of network structure with different func-tional groups in the modified resin (Co-g-AP3)which can accommodate large molecules and inter-act with the functional groups present in the dyemolecules Also the relatively high adsorption per-centage of Co-Hyd resin can be due to highly poresstructure of this resin as shown in Figure 3c

4 ConclusionsAdsorption represents a potentially cost-effectiveway of eliminating toxic heavy metals from indus-trial wastewaters Reusable polymer-based adsor-bents have been recognized as a promising class oflow-cost adsorbents for the removal of heavy-metalions from aqueous waste streams In this study thereaction of AP and different crosslink agents withpoly(MMA-co-MA) led to the synthesis of signifi-cantly capable chelating resins for the removal ofheavy metal ions such as Cu2+ Cd2+ and Hg2+ fromaqueous solution These results suggest that the pre-pared chelating resin beads are good heavy metalions adsorbents in various pH values and can havegreat potential applications in environmental pro-tection The affinity order of metal ions on a molarbasis is as Cu2+gtCd2+gtHg2+ The new adsorbentshave higher adsorption properties than other adsor-bents reported by some researchers In addition thecapacity of dyes removal of the resin beads wasinvestigated and the results showed that the adsorbeddye increased by using crosslinked resin

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

194

Figure 7 Desorption of Hg2+ ion from the chelating resinsbeads that had been preadsorbed under condi-tions given in Figure 6 as a function of submer-sion time in 25 mL of HCl (02 M) solution for1 h at 25degC

Figure 8 Dyes removal efficiency by the prepared resinbeads (005 g of the chelating resin in 10 mLaqueous solution containing a dye with initialconcentration = 100 mgL at 25degC for 12 h with-out pH adjustment)

References [1] Matsuto T Jung C H Tanaka N Material and heavy

metal balance in a recycling facility for home electri-cal appliances Waste Management 24 425ndash436 (2004)DOI 101016jwasman200312002

[2] Srivastava N K Majumder C B Novel biofiltrationmethods for the treatment of heavy metals from indus-trial wastewater Journal of Hazardous Materials 1511ndash8 (2008)DOI 101016jjhazmat200709101

[3] Vaaramaa K Lehto J Removal of metals and anionsfrom drinking water by ion exchange Desalination155 157ndash170 (2003)DOI 101016S0011-9164(03)00293-5

[4] ernaacute M Use of solvent extraction for the removal ofheavy metals from liquid wastes Environmental Mon-itoring and Assessment 34 151ndash162 (1995) DOI 101007BF00546029

[5] Hu X Li Y Wang Y Li X Li H Liu X Zhang PAdsorption kinetics thermodynamics and isotherm ofthiacalix[4]arene-loaded resin to heavy metal ionsDesalination 259 76ndash83 (2010)DOI 101016jdesal201004032

[6] Al-Rashdi B A M Johnson D J Hilal N Removalof heavy metal ions by nanofiltration Desalination315 2ndash17 (2013)DOI 101016jdesal201205022

[7] Ozaki H Sharma K Saktaywin W Performance ofan ultra-low-pressure reverse osmosis membrane(ULPROM) for separating heavy metal effects of inter-ference parameters Desalination 144 287ndash294 (2002)DOI 101016S0011-9164(02)00329-6

[8] Peterskovaacute M Valderrama C Gibert O Cortina JL Extraction of valuable metal ions (Cs Rb Li U)from reverse osmosis concentrate using selective sor-bents Desalination 286 316ndash323 (2012)DOI 101016jdesal201111042

[9] Soleimani Lashkenari M Davodi B Ghorbani MEisazadeh H Use of core-shell polyanilinepoly-styrene nanocomposite for removal of Cr(VI) HighPerformance Polymers 24 345ndash355 (2012)DOI 1011770954008311436222

[10] Li L Li Y Luo X Deng J Yang W Helical poly(N-propargylamide)s with functional catechol groupsSynthesis and adsorption of metal ions in aqueoussolution Reactive and Functional Polymers 70 938ndash943 (2010)DOI 101016jreactfunctpolym201009006

[11] Jitjaicham S Kampalanonwat P Supaphol P Metaladsorption behavior of 24-dinitrophenyl hydrazinemodified polyacrylonitrile nanofibers Express Poly-mer Letters 7 832ndash841 (2013)DOI 103144expresspolymlett201380

[12] Co$kun R Soykan C Saccedilak M Removal of someheavy metal ions from aqueous solution by adsorptionusing poly(ethylene terephthalate)-g-itaconic acidacryl -amide fiber Reactive and Functional Polymers 66599ndash608 (2006)DOI 101016jreactfunctpolym200510012

[13] Sankar R Sasidaran M Kaliyappan T Synthesischaracterization thermal and chelation properties ofnew polymeric hydrazone based on 24-dihydroxy ben-zaldehyde High Performance Polymers 23 32ndash39(2011)DOI 1011770954008310381148

[14] Sasidaran M Sankar R Kandasamy P Vijayalak-shmi S Kaliyappan T Chelating and biological prop-erties of an azo polymer resin Synthesis characteriza-tion and its application High Performance Polymers23 602ndash609 (2011)DOI 1011770954008311428531

[15] Dinu M V Dragan E S Heavy metals adsorption onsome iminodiacetate chelating resins as a function ofthe adsorption parameters Reactive and FunctionalPolymers 68 1346ndash1354 (2008)DOI 101016jreactfunctpolym200806011

[16] Vasconcelos H L Faacutevere V T Gonccedilalves N SLaranjeira M C M Chitosan modified with ReactiveBlue 2 dye on adsorption equilibrium of Cu(II) andNi(II) ions Reactive and Functional Polymers 671052ndash1060 (2007)DOI 101016jreactfunctpolym200706009

[17] Takagi K Miwa S Yuki Y Synthesis of poly(tri-azinylstyrene) containing nitrogen-based ligand andfunction as metal ion adsorbent and oxidation catalystReactive and Functional Polymers 66 1718ndash1724(2006)DOI 101016jreactfunctpolym200607005

[18] Ahamed M E H Mbianda X Y Mulaba-BafubiandiA F Marjanovic L Ion imprinted polymers for theselective extraction of silver(I) ions in aqueous mediaKinetic modeling and isotherm studies Reactive andFunctional Polymers 73 474ndash483 (2013)DOI 101016jreactfunctpolym201211011

[19] Wang C-C Wang C-C Adsorption characteristics ofmetal complexes by chelated copolymers with aminogroup Reactive and Functional Polymers 66 343ndash356(2006)DOI 101016jreactfunctpolym200508011

[20] Vasconcelos H L Camargo T P Gonccedilalves N SNeves A Laranjeira M C M Faacutevere V T Chitosancrosslinked with a metal complexing agent Synthesischaracterization and copper(II) ions adsorption Reac-tive and Functional Polymers 68 572ndash579 (2008)DOI 101016jreactfunctpolym200710024

[21] Huang J Zhang K The high flux poly (m-phenyleneisophthalamide) nanofiltration membrane for dyepurification and desalination Desalination 282 19ndash26 (2011)DOI 101016jdesal201109045

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

195

AP to form an alkylamide linkage and a carboxylicacid group and (3) poly(MMA-co-MA) wasreacted with AP and a crosslink agent such as EDDETA and TETA to form a network structure withmany adsorption sites for metal ions Comparisonof the FT-IR spectra of poly(MMA-co-MA) andCo-g-AP3 as shown in Figure 2a and 2b indicatesthat characteristic bands of the anhydride linkage inpoly(MMA-co-MA) at 1747 1809 and 1856 cmndash1

disappeared after reaction with TETA and the formedamide linkage (ndashCOndashNHndash) showed absorption bandat ~1676 cmndash1 To investigate the effect of chemicalreactions in the copolymer matrix the phase mor-phology was studied using SEM Figure 3andash3cshows representative SEM images of Co-g-AP Co-g-AP3 and Co-Hyd As can be seen in these figuresthe roughness of the surface and particularly the

porous surface after hydrolysis Figure 3c shouldbe considered as a factor providing chelating abilityfor the resins On that basis the adsorbents presentan adequate morphology with disordered distribu-tion of sizes which can be the main reason of theirhigh surface ability for the removal of metal ionsTo observe morphological properties such as sur-face porosity texture and roughness micrographs ofthe surface and cross section of Co-g-AP3 before andafter metal ion adsorption were registered by usingAFM Figure 3d shows smoother surface of Co-g-AP3 before metal ion adsorption while Figure 3ereveals a predominantly hill-valley-structured surfacewith irregular pores of nanoscale topography aftermetal ion adsorption The roughness can also be seenin 3D images of the surface of metal ion adsorbedsample with their histograms show size distribu-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

191

Figure 3 Representative FESEM images of Co-g-AP (a) Co-g-AP3 (b) and CondashHyd (c) AFM images of Co-g-AP3before (d) and after (e) Hg2+ ion adsorption

tions The average size for the particles of Co-g-AP3 before adsorption is in the range of 15ndash17 nmand after metal ion adsorption is in the range of 20ndash28 nm respectively The crosslinked beads are hydro -philic matrices ie hydrogels therefore they donot dissolve in aqueous media but do swell depend-ing on the degree of crosslinking and on the hydro -philicity of the matrix The equilibrium swellingratio of the resin beads are shown in Figure 4 Sev-eral possible factors are contributing in water absorp-tion of the beads such as incorporation of hydrop -hilic amino and amide groups into the polymermatrix which increases water absorption and intro-duction of hydrophobic ndashCH2ndash units into the poly-mer structure via crosslink agent such as TETA whichreduces water uptake of the resin As can be seen inFigure 4 the copolymers Co-g-AP and Co-Hydshowed the highest water absorption These twocopolymers are not crosslinked and they are opensystems with highly hydrophilic groups of car-boxylic acids The water absorption of threecrosslinked copolymers showed order of Co-g-AP3gtCo-g-AP2gtCO-g-AP1 which depended on the chem-ical structure of the curing agent (ED DETA andTETA respectively) and the network structure TheXRD patterns of all copolymers showed only a broaddiffraction hump at about 2$ = 15ndash20 indicating theamorphous nature of the prepared resin beads

32 Adsorption of heavy metal ionsIn this research the FT-IR spectroscopy was used

to monitor the structural changes take place in thechelating resins as a result of metal-ion complexa-tion Therefore the first information about the struc-tural changes such as shift or elimination of a cer-tain band present in the starting resin as well as theappearance of new bands caused by the complexa-tion of the resin with metal ions was provided by

the FT-IR spectra The bonding mode of Hg2+ tochelating resin was examined by comparing the FT-IR spectra of poly(MMAndashcondashMA) and Co-g-AP3with the spectrum of [Hgndash(Co-g-AP3)] complex Asshown in Figure 2c the FT-IR spectrum of Hg-(Co-g-AP3) is quite different from the spectrum of poly(MMA-co-MA) in Figure 2a Two strong absorptionbands at 1401 and 1544 cmndash1 are observed in thespectrum of [Hgndash(Co-g-AP3)] complex which areassigned to the symmetric (vs COOndash) and asym-metric (vas COOndash) vibration absorption of the car-boxylic groups respectively [25] The shift of FT-IR peak for the carbonyl group of carboxylate couldindicate whether the bonding between the ligandand metal ion was covalent or ionic [26] In thisstudy there is small shift towards higher frequencywhich can be taken as evidence for formation ofcovalent bond between metal ions and carbonylgroups The absorption bands characteristic of thearomatic AP in the resin matrix are observed at 1032914 767 and 703 cmndash1 which were not influenced bythe metal complexation The adsorption capacity ofthe chelating resin beads for the tested metal ions ofCu2+ Cd2+ and Hg2+ at pH 3 6 and 9 are shown inFigure 5 The results demonstrated a relativelyweak dependency of metal ions sorption on the pHvariations A relatively high adsorption of about60ndash80 was observed at various pH values for thetested metal ions by all the chelating resin beadsAdsorbents with carboxyl sulfonic and phosphonicgroups on the surface remove adsorbates throughion exchange while those containing nitrogen suchas amine hydrazine thioamide and imidazolinegroups not only chelate cationic metal ions butalso adsorb anionic adsorbates through electrostaticinteractions [27ndash29] All the prepared resins havecarboxylic acid and amine groups as potential ionexchangecomplexing units In the acidic condi-tions the degree of protonation of amine groupsaffects their ability to bind metal ions Thereforethe relatively high adsorption of metal ions in acidicconditions could be explained by the complex for-mation between M+2 and ndashCOOH groups The ndashCOOH groups are formed as a result of reactionbetween anhydride of the copolymer and amine ofthe crosslink agent and also can be due to hydroly-sis of the ester linkage in the MMA repeating unitAs can be seen in Figure 5 the dependency of adsorp-tion capacity of these resins on the pH value isrelated to the functional groups of adsorbent and

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

192

Figure 4 Water uptake of the chelating resins

type of metal ion For example all the chelatingresins adsorbed about 55 (Q = 031 mmolg) Cd2+

at pH 3 which increased to over 81 (Q =046 mmolg) at pH 9 while adsorption of Cu2+ was73 (Q = 042 mmolg) and 87 (Q = 051 mmolg)respectively at same pH values Therefore in gen-eral a high affinity was observed for adsorption ofthe tested metal ions by all the prepared resins espe-cially by Co-Hyd and Co-g-AP3 at various pH Thiscan be due to presence of different metal ion adsorp-tion sites such as carboxylate and amine groups inthe copolymer matrix The order of adsorption per-centage changed as follows Co-g-AP3Co-HydgtCo-g-AP2gtCo-g-AP1gtCo-g-AP The order of these

three kinds of metal ion chelation on mass basis forthe single component metal is Cu2+gtCd2+gtHg2+This affinity trend is presented on the mass basis[mg] metal chelation per gram resin beads and theseunits are important in quantifying respective metalcapacities in real terms Incorporation of TETA ascrosslinking agent with long alkyl chain and fouramine groups into the resin structure has signifi-cantly increased the adsorption capacity of the net-work The results show that the adsorption capacitywith Hg2+ (at pH = 6) is 714 mgg for Co-Hyd7263 mgg for Co-g-AP 73 mgg for Co-g-AP1763 mgg for Co-g-AP2 and 858 mgg for Co-g-AP3 Figure 6 illustrates the metal ions binding ontothe chelating resins Adsorbents used in heavy metalions removal are in particulate form in most of thecases In the literature different affinity sorbentswith a wide range of adsorption capacities for heavymetal ions have been reported Shreedhara-Murthyand Ryan found 5ndash27 mgg Cu(II) removal by cel-lulose dithiocarbamate resins [30] Roozemondshowed 32 mgg Cu(II) with pyrazole-containingpoly(styrene-divinyl-benzene) sorbents [31] Say etal [32] achieved 7141 4688 and 6394 mggadsorption capacities for Pb(II) Cr(III) and Cd(II)respectively with poly(HEMA-MAH) beads Karaet al [33] have prepared poly(EGDMA-VIM) beadsand found the chelation capacities of these beadswere 694 and 1148 mgg for Cd(II) and Pb(II)respectively Duran et al [34] have prepared [poly(VP-PEGMA-EGDMA)] beads and found the chela-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

193

Figure 5 Effect of the initial pH of the testing solutions onthe adsorption capacity (Q) and percentage (R[]) for the tested metal ions Initial ion concen-tration = 100 mgL sample dose = 5 mg50 mLtemperature = 25degC and contact time = 24 h

Figure 6 Illustration of metalndashchelating resin complexes ofCo-Hyd Co-g-AP and the crosslinked chelatingresin

tion capacities of these beads were 1823 16501581 and 1825 mgg for Pb(II) Cd(II) Cr(III) andCu(II) respectively

33 Desorption of metal ions from thechelating resin

The repeated use of the resins is an essential param-eter in improving process economics Desorption ofmetal ions from resinndashmetal ion complexes wascarried out by HCl (02 M ) treatment at room tem-perature and the amount of metal ions desorbed in 1hour was measured As shown in Figure 7 morethan 96 of adsorbed metal ions are recovered inthe acid leaching process indicating that chelation(ie binding of heavy metal ions with functionalgroups in resin) is completely reversible In order toobtain the reusability of the resins chelationndashelu-tion cycle was repeated successfully five times byusing the same adsorbent and the results are shownin Figure 7

34 Dyes removalThe adsorption of dyes with the prepared chelatingresin beads was carried out by using three commer-cial azo dyes containing different functional groupssuch as ndashN=Nndash chlorine oxadiazine and sulfate(Figure 1) The results for the dyes adsorption areshown in Figure 8 The order for the dyes removalby the resins is Co-g-AP3gtCo-Hydgt poly(MMA-co-MA) indicating higher capacity for the cross -linked resin in comparison with the results obtained

for the unmodified copolymer This can be due topresence of network structure with different func-tional groups in the modified resin (Co-g-AP3)which can accommodate large molecules and inter-act with the functional groups present in the dyemolecules Also the relatively high adsorption per-centage of Co-Hyd resin can be due to highly poresstructure of this resin as shown in Figure 3c

4 ConclusionsAdsorption represents a potentially cost-effectiveway of eliminating toxic heavy metals from indus-trial wastewaters Reusable polymer-based adsor-bents have been recognized as a promising class oflow-cost adsorbents for the removal of heavy-metalions from aqueous waste streams In this study thereaction of AP and different crosslink agents withpoly(MMA-co-MA) led to the synthesis of signifi-cantly capable chelating resins for the removal ofheavy metal ions such as Cu2+ Cd2+ and Hg2+ fromaqueous solution These results suggest that the pre-pared chelating resin beads are good heavy metalions adsorbents in various pH values and can havegreat potential applications in environmental pro-tection The affinity order of metal ions on a molarbasis is as Cu2+gtCd2+gtHg2+ The new adsorbentshave higher adsorption properties than other adsor-bents reported by some researchers In addition thecapacity of dyes removal of the resin beads wasinvestigated and the results showed that the adsorbeddye increased by using crosslinked resin

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

194

Figure 7 Desorption of Hg2+ ion from the chelating resinsbeads that had been preadsorbed under condi-tions given in Figure 6 as a function of submer-sion time in 25 mL of HCl (02 M) solution for1 h at 25degC

Figure 8 Dyes removal efficiency by the prepared resinbeads (005 g of the chelating resin in 10 mLaqueous solution containing a dye with initialconcentration = 100 mgL at 25degC for 12 h with-out pH adjustment)

References [1] Matsuto T Jung C H Tanaka N Material and heavy

metal balance in a recycling facility for home electri-cal appliances Waste Management 24 425ndash436 (2004)DOI 101016jwasman200312002

[2] Srivastava N K Majumder C B Novel biofiltrationmethods for the treatment of heavy metals from indus-trial wastewater Journal of Hazardous Materials 1511ndash8 (2008)DOI 101016jjhazmat200709101

[3] Vaaramaa K Lehto J Removal of metals and anionsfrom drinking water by ion exchange Desalination155 157ndash170 (2003)DOI 101016S0011-9164(03)00293-5

[4] ernaacute M Use of solvent extraction for the removal ofheavy metals from liquid wastes Environmental Mon-itoring and Assessment 34 151ndash162 (1995) DOI 101007BF00546029

[5] Hu X Li Y Wang Y Li X Li H Liu X Zhang PAdsorption kinetics thermodynamics and isotherm ofthiacalix[4]arene-loaded resin to heavy metal ionsDesalination 259 76ndash83 (2010)DOI 101016jdesal201004032

[6] Al-Rashdi B A M Johnson D J Hilal N Removalof heavy metal ions by nanofiltration Desalination315 2ndash17 (2013)DOI 101016jdesal201205022

[7] Ozaki H Sharma K Saktaywin W Performance ofan ultra-low-pressure reverse osmosis membrane(ULPROM) for separating heavy metal effects of inter-ference parameters Desalination 144 287ndash294 (2002)DOI 101016S0011-9164(02)00329-6

[8] Peterskovaacute M Valderrama C Gibert O Cortina JL Extraction of valuable metal ions (Cs Rb Li U)from reverse osmosis concentrate using selective sor-bents Desalination 286 316ndash323 (2012)DOI 101016jdesal201111042

[9] Soleimani Lashkenari M Davodi B Ghorbani MEisazadeh H Use of core-shell polyanilinepoly-styrene nanocomposite for removal of Cr(VI) HighPerformance Polymers 24 345ndash355 (2012)DOI 1011770954008311436222

[10] Li L Li Y Luo X Deng J Yang W Helical poly(N-propargylamide)s with functional catechol groupsSynthesis and adsorption of metal ions in aqueoussolution Reactive and Functional Polymers 70 938ndash943 (2010)DOI 101016jreactfunctpolym201009006

[11] Jitjaicham S Kampalanonwat P Supaphol P Metaladsorption behavior of 24-dinitrophenyl hydrazinemodified polyacrylonitrile nanofibers Express Poly-mer Letters 7 832ndash841 (2013)DOI 103144expresspolymlett201380

[12] Co$kun R Soykan C Saccedilak M Removal of someheavy metal ions from aqueous solution by adsorptionusing poly(ethylene terephthalate)-g-itaconic acidacryl -amide fiber Reactive and Functional Polymers 66599ndash608 (2006)DOI 101016jreactfunctpolym200510012

[13] Sankar R Sasidaran M Kaliyappan T Synthesischaracterization thermal and chelation properties ofnew polymeric hydrazone based on 24-dihydroxy ben-zaldehyde High Performance Polymers 23 32ndash39(2011)DOI 1011770954008310381148

[14] Sasidaran M Sankar R Kandasamy P Vijayalak-shmi S Kaliyappan T Chelating and biological prop-erties of an azo polymer resin Synthesis characteriza-tion and its application High Performance Polymers23 602ndash609 (2011)DOI 1011770954008311428531

[15] Dinu M V Dragan E S Heavy metals adsorption onsome iminodiacetate chelating resins as a function ofthe adsorption parameters Reactive and FunctionalPolymers 68 1346ndash1354 (2008)DOI 101016jreactfunctpolym200806011

[16] Vasconcelos H L Faacutevere V T Gonccedilalves N SLaranjeira M C M Chitosan modified with ReactiveBlue 2 dye on adsorption equilibrium of Cu(II) andNi(II) ions Reactive and Functional Polymers 671052ndash1060 (2007)DOI 101016jreactfunctpolym200706009

[17] Takagi K Miwa S Yuki Y Synthesis of poly(tri-azinylstyrene) containing nitrogen-based ligand andfunction as metal ion adsorbent and oxidation catalystReactive and Functional Polymers 66 1718ndash1724(2006)DOI 101016jreactfunctpolym200607005

[18] Ahamed M E H Mbianda X Y Mulaba-BafubiandiA F Marjanovic L Ion imprinted polymers for theselective extraction of silver(I) ions in aqueous mediaKinetic modeling and isotherm studies Reactive andFunctional Polymers 73 474ndash483 (2013)DOI 101016jreactfunctpolym201211011

[19] Wang C-C Wang C-C Adsorption characteristics ofmetal complexes by chelated copolymers with aminogroup Reactive and Functional Polymers 66 343ndash356(2006)DOI 101016jreactfunctpolym200508011

[20] Vasconcelos H L Camargo T P Gonccedilalves N SNeves A Laranjeira M C M Faacutevere V T Chitosancrosslinked with a metal complexing agent Synthesischaracterization and copper(II) ions adsorption Reac-tive and Functional Polymers 68 572ndash579 (2008)DOI 101016jreactfunctpolym200710024

[21] Huang J Zhang K The high flux poly (m-phenyleneisophthalamide) nanofiltration membrane for dyepurification and desalination Desalination 282 19ndash26 (2011)DOI 101016jdesal201109045

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

195

tions The average size for the particles of Co-g-AP3 before adsorption is in the range of 15ndash17 nmand after metal ion adsorption is in the range of 20ndash28 nm respectively The crosslinked beads are hydro -philic matrices ie hydrogels therefore they donot dissolve in aqueous media but do swell depend-ing on the degree of crosslinking and on the hydro -philicity of the matrix The equilibrium swellingratio of the resin beads are shown in Figure 4 Sev-eral possible factors are contributing in water absorp-tion of the beads such as incorporation of hydrop -hilic amino and amide groups into the polymermatrix which increases water absorption and intro-duction of hydrophobic ndashCH2ndash units into the poly-mer structure via crosslink agent such as TETA whichreduces water uptake of the resin As can be seen inFigure 4 the copolymers Co-g-AP and Co-Hydshowed the highest water absorption These twocopolymers are not crosslinked and they are opensystems with highly hydrophilic groups of car-boxylic acids The water absorption of threecrosslinked copolymers showed order of Co-g-AP3gtCo-g-AP2gtCO-g-AP1 which depended on the chem-ical structure of the curing agent (ED DETA andTETA respectively) and the network structure TheXRD patterns of all copolymers showed only a broaddiffraction hump at about 2$ = 15ndash20 indicating theamorphous nature of the prepared resin beads

32 Adsorption of heavy metal ionsIn this research the FT-IR spectroscopy was used

to monitor the structural changes take place in thechelating resins as a result of metal-ion complexa-tion Therefore the first information about the struc-tural changes such as shift or elimination of a cer-tain band present in the starting resin as well as theappearance of new bands caused by the complexa-tion of the resin with metal ions was provided by

the FT-IR spectra The bonding mode of Hg2+ tochelating resin was examined by comparing the FT-IR spectra of poly(MMAndashcondashMA) and Co-g-AP3with the spectrum of [Hgndash(Co-g-AP3)] complex Asshown in Figure 2c the FT-IR spectrum of Hg-(Co-g-AP3) is quite different from the spectrum of poly(MMA-co-MA) in Figure 2a Two strong absorptionbands at 1401 and 1544 cmndash1 are observed in thespectrum of [Hgndash(Co-g-AP3)] complex which areassigned to the symmetric (vs COOndash) and asym-metric (vas COOndash) vibration absorption of the car-boxylic groups respectively [25] The shift of FT-IR peak for the carbonyl group of carboxylate couldindicate whether the bonding between the ligandand metal ion was covalent or ionic [26] In thisstudy there is small shift towards higher frequencywhich can be taken as evidence for formation ofcovalent bond between metal ions and carbonylgroups The absorption bands characteristic of thearomatic AP in the resin matrix are observed at 1032914 767 and 703 cmndash1 which were not influenced bythe metal complexation The adsorption capacity ofthe chelating resin beads for the tested metal ions ofCu2+ Cd2+ and Hg2+ at pH 3 6 and 9 are shown inFigure 5 The results demonstrated a relativelyweak dependency of metal ions sorption on the pHvariations A relatively high adsorption of about60ndash80 was observed at various pH values for thetested metal ions by all the chelating resin beadsAdsorbents with carboxyl sulfonic and phosphonicgroups on the surface remove adsorbates throughion exchange while those containing nitrogen suchas amine hydrazine thioamide and imidazolinegroups not only chelate cationic metal ions butalso adsorb anionic adsorbates through electrostaticinteractions [27ndash29] All the prepared resins havecarboxylic acid and amine groups as potential ionexchangecomplexing units In the acidic condi-tions the degree of protonation of amine groupsaffects their ability to bind metal ions Thereforethe relatively high adsorption of metal ions in acidicconditions could be explained by the complex for-mation between M+2 and ndashCOOH groups The ndashCOOH groups are formed as a result of reactionbetween anhydride of the copolymer and amine ofthe crosslink agent and also can be due to hydroly-sis of the ester linkage in the MMA repeating unitAs can be seen in Figure 5 the dependency of adsorp-tion capacity of these resins on the pH value isrelated to the functional groups of adsorbent and

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

192

Figure 4 Water uptake of the chelating resins

type of metal ion For example all the chelatingresins adsorbed about 55 (Q = 031 mmolg) Cd2+

at pH 3 which increased to over 81 (Q =046 mmolg) at pH 9 while adsorption of Cu2+ was73 (Q = 042 mmolg) and 87 (Q = 051 mmolg)respectively at same pH values Therefore in gen-eral a high affinity was observed for adsorption ofthe tested metal ions by all the prepared resins espe-cially by Co-Hyd and Co-g-AP3 at various pH Thiscan be due to presence of different metal ion adsorp-tion sites such as carboxylate and amine groups inthe copolymer matrix The order of adsorption per-centage changed as follows Co-g-AP3Co-HydgtCo-g-AP2gtCo-g-AP1gtCo-g-AP The order of these

three kinds of metal ion chelation on mass basis forthe single component metal is Cu2+gtCd2+gtHg2+This affinity trend is presented on the mass basis[mg] metal chelation per gram resin beads and theseunits are important in quantifying respective metalcapacities in real terms Incorporation of TETA ascrosslinking agent with long alkyl chain and fouramine groups into the resin structure has signifi-cantly increased the adsorption capacity of the net-work The results show that the adsorption capacitywith Hg2+ (at pH = 6) is 714 mgg for Co-Hyd7263 mgg for Co-g-AP 73 mgg for Co-g-AP1763 mgg for Co-g-AP2 and 858 mgg for Co-g-AP3 Figure 6 illustrates the metal ions binding ontothe chelating resins Adsorbents used in heavy metalions removal are in particulate form in most of thecases In the literature different affinity sorbentswith a wide range of adsorption capacities for heavymetal ions have been reported Shreedhara-Murthyand Ryan found 5ndash27 mgg Cu(II) removal by cel-lulose dithiocarbamate resins [30] Roozemondshowed 32 mgg Cu(II) with pyrazole-containingpoly(styrene-divinyl-benzene) sorbents [31] Say etal [32] achieved 7141 4688 and 6394 mggadsorption capacities for Pb(II) Cr(III) and Cd(II)respectively with poly(HEMA-MAH) beads Karaet al [33] have prepared poly(EGDMA-VIM) beadsand found the chelation capacities of these beadswere 694 and 1148 mgg for Cd(II) and Pb(II)respectively Duran et al [34] have prepared [poly(VP-PEGMA-EGDMA)] beads and found the chela-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

193

Figure 5 Effect of the initial pH of the testing solutions onthe adsorption capacity (Q) and percentage (R[]) for the tested metal ions Initial ion concen-tration = 100 mgL sample dose = 5 mg50 mLtemperature = 25degC and contact time = 24 h

Figure 6 Illustration of metalndashchelating resin complexes ofCo-Hyd Co-g-AP and the crosslinked chelatingresin

tion capacities of these beads were 1823 16501581 and 1825 mgg for Pb(II) Cd(II) Cr(III) andCu(II) respectively

33 Desorption of metal ions from thechelating resin

The repeated use of the resins is an essential param-eter in improving process economics Desorption ofmetal ions from resinndashmetal ion complexes wascarried out by HCl (02 M ) treatment at room tem-perature and the amount of metal ions desorbed in 1hour was measured As shown in Figure 7 morethan 96 of adsorbed metal ions are recovered inthe acid leaching process indicating that chelation(ie binding of heavy metal ions with functionalgroups in resin) is completely reversible In order toobtain the reusability of the resins chelationndashelu-tion cycle was repeated successfully five times byusing the same adsorbent and the results are shownin Figure 7

34 Dyes removalThe adsorption of dyes with the prepared chelatingresin beads was carried out by using three commer-cial azo dyes containing different functional groupssuch as ndashN=Nndash chlorine oxadiazine and sulfate(Figure 1) The results for the dyes adsorption areshown in Figure 8 The order for the dyes removalby the resins is Co-g-AP3gtCo-Hydgt poly(MMA-co-MA) indicating higher capacity for the cross -linked resin in comparison with the results obtained

for the unmodified copolymer This can be due topresence of network structure with different func-tional groups in the modified resin (Co-g-AP3)which can accommodate large molecules and inter-act with the functional groups present in the dyemolecules Also the relatively high adsorption per-centage of Co-Hyd resin can be due to highly poresstructure of this resin as shown in Figure 3c

4 ConclusionsAdsorption represents a potentially cost-effectiveway of eliminating toxic heavy metals from indus-trial wastewaters Reusable polymer-based adsor-bents have been recognized as a promising class oflow-cost adsorbents for the removal of heavy-metalions from aqueous waste streams In this study thereaction of AP and different crosslink agents withpoly(MMA-co-MA) led to the synthesis of signifi-cantly capable chelating resins for the removal ofheavy metal ions such as Cu2+ Cd2+ and Hg2+ fromaqueous solution These results suggest that the pre-pared chelating resin beads are good heavy metalions adsorbents in various pH values and can havegreat potential applications in environmental pro-tection The affinity order of metal ions on a molarbasis is as Cu2+gtCd2+gtHg2+ The new adsorbentshave higher adsorption properties than other adsor-bents reported by some researchers In addition thecapacity of dyes removal of the resin beads wasinvestigated and the results showed that the adsorbeddye increased by using crosslinked resin

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

194

Figure 7 Desorption of Hg2+ ion from the chelating resinsbeads that had been preadsorbed under condi-tions given in Figure 6 as a function of submer-sion time in 25 mL of HCl (02 M) solution for1 h at 25degC

Figure 8 Dyes removal efficiency by the prepared resinbeads (005 g of the chelating resin in 10 mLaqueous solution containing a dye with initialconcentration = 100 mgL at 25degC for 12 h with-out pH adjustment)

References [1] Matsuto T Jung C H Tanaka N Material and heavy

metal balance in a recycling facility for home electri-cal appliances Waste Management 24 425ndash436 (2004)DOI 101016jwasman200312002

[2] Srivastava N K Majumder C B Novel biofiltrationmethods for the treatment of heavy metals from indus-trial wastewater Journal of Hazardous Materials 1511ndash8 (2008)DOI 101016jjhazmat200709101

[3] Vaaramaa K Lehto J Removal of metals and anionsfrom drinking water by ion exchange Desalination155 157ndash170 (2003)DOI 101016S0011-9164(03)00293-5

[4] ernaacute M Use of solvent extraction for the removal ofheavy metals from liquid wastes Environmental Mon-itoring and Assessment 34 151ndash162 (1995) DOI 101007BF00546029

[5] Hu X Li Y Wang Y Li X Li H Liu X Zhang PAdsorption kinetics thermodynamics and isotherm ofthiacalix[4]arene-loaded resin to heavy metal ionsDesalination 259 76ndash83 (2010)DOI 101016jdesal201004032

[6] Al-Rashdi B A M Johnson D J Hilal N Removalof heavy metal ions by nanofiltration Desalination315 2ndash17 (2013)DOI 101016jdesal201205022

[7] Ozaki H Sharma K Saktaywin W Performance ofan ultra-low-pressure reverse osmosis membrane(ULPROM) for separating heavy metal effects of inter-ference parameters Desalination 144 287ndash294 (2002)DOI 101016S0011-9164(02)00329-6

[8] Peterskovaacute M Valderrama C Gibert O Cortina JL Extraction of valuable metal ions (Cs Rb Li U)from reverse osmosis concentrate using selective sor-bents Desalination 286 316ndash323 (2012)DOI 101016jdesal201111042

[9] Soleimani Lashkenari M Davodi B Ghorbani MEisazadeh H Use of core-shell polyanilinepoly-styrene nanocomposite for removal of Cr(VI) HighPerformance Polymers 24 345ndash355 (2012)DOI 1011770954008311436222

[10] Li L Li Y Luo X Deng J Yang W Helical poly(N-propargylamide)s with functional catechol groupsSynthesis and adsorption of metal ions in aqueoussolution Reactive and Functional Polymers 70 938ndash943 (2010)DOI 101016jreactfunctpolym201009006

[11] Jitjaicham S Kampalanonwat P Supaphol P Metaladsorption behavior of 24-dinitrophenyl hydrazinemodified polyacrylonitrile nanofibers Express Poly-mer Letters 7 832ndash841 (2013)DOI 103144expresspolymlett201380

[12] Co$kun R Soykan C Saccedilak M Removal of someheavy metal ions from aqueous solution by adsorptionusing poly(ethylene terephthalate)-g-itaconic acidacryl -amide fiber Reactive and Functional Polymers 66599ndash608 (2006)DOI 101016jreactfunctpolym200510012

[13] Sankar R Sasidaran M Kaliyappan T Synthesischaracterization thermal and chelation properties ofnew polymeric hydrazone based on 24-dihydroxy ben-zaldehyde High Performance Polymers 23 32ndash39(2011)DOI 1011770954008310381148

[14] Sasidaran M Sankar R Kandasamy P Vijayalak-shmi S Kaliyappan T Chelating and biological prop-erties of an azo polymer resin Synthesis characteriza-tion and its application High Performance Polymers23 602ndash609 (2011)DOI 1011770954008311428531

[15] Dinu M V Dragan E S Heavy metals adsorption onsome iminodiacetate chelating resins as a function ofthe adsorption parameters Reactive and FunctionalPolymers 68 1346ndash1354 (2008)DOI 101016jreactfunctpolym200806011

[16] Vasconcelos H L Faacutevere V T Gonccedilalves N SLaranjeira M C M Chitosan modified with ReactiveBlue 2 dye on adsorption equilibrium of Cu(II) andNi(II) ions Reactive and Functional Polymers 671052ndash1060 (2007)DOI 101016jreactfunctpolym200706009

[17] Takagi K Miwa S Yuki Y Synthesis of poly(tri-azinylstyrene) containing nitrogen-based ligand andfunction as metal ion adsorbent and oxidation catalystReactive and Functional Polymers 66 1718ndash1724(2006)DOI 101016jreactfunctpolym200607005

[18] Ahamed M E H Mbianda X Y Mulaba-BafubiandiA F Marjanovic L Ion imprinted polymers for theselective extraction of silver(I) ions in aqueous mediaKinetic modeling and isotherm studies Reactive andFunctional Polymers 73 474ndash483 (2013)DOI 101016jreactfunctpolym201211011

[19] Wang C-C Wang C-C Adsorption characteristics ofmetal complexes by chelated copolymers with aminogroup Reactive and Functional Polymers 66 343ndash356(2006)DOI 101016jreactfunctpolym200508011

[20] Vasconcelos H L Camargo T P Gonccedilalves N SNeves A Laranjeira M C M Faacutevere V T Chitosancrosslinked with a metal complexing agent Synthesischaracterization and copper(II) ions adsorption Reac-tive and Functional Polymers 68 572ndash579 (2008)DOI 101016jreactfunctpolym200710024

[21] Huang J Zhang K The high flux poly (m-phenyleneisophthalamide) nanofiltration membrane for dyepurification and desalination Desalination 282 19ndash26 (2011)DOI 101016jdesal201109045

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

195

type of metal ion For example all the chelatingresins adsorbed about 55 (Q = 031 mmolg) Cd2+

at pH 3 which increased to over 81 (Q =046 mmolg) at pH 9 while adsorption of Cu2+ was73 (Q = 042 mmolg) and 87 (Q = 051 mmolg)respectively at same pH values Therefore in gen-eral a high affinity was observed for adsorption ofthe tested metal ions by all the prepared resins espe-cially by Co-Hyd and Co-g-AP3 at various pH Thiscan be due to presence of different metal ion adsorp-tion sites such as carboxylate and amine groups inthe copolymer matrix The order of adsorption per-centage changed as follows Co-g-AP3Co-HydgtCo-g-AP2gtCo-g-AP1gtCo-g-AP The order of these

three kinds of metal ion chelation on mass basis forthe single component metal is Cu2+gtCd2+gtHg2+This affinity trend is presented on the mass basis[mg] metal chelation per gram resin beads and theseunits are important in quantifying respective metalcapacities in real terms Incorporation of TETA ascrosslinking agent with long alkyl chain and fouramine groups into the resin structure has signifi-cantly increased the adsorption capacity of the net-work The results show that the adsorption capacitywith Hg2+ (at pH = 6) is 714 mgg for Co-Hyd7263 mgg for Co-g-AP 73 mgg for Co-g-AP1763 mgg for Co-g-AP2 and 858 mgg for Co-g-AP3 Figure 6 illustrates the metal ions binding ontothe chelating resins Adsorbents used in heavy metalions removal are in particulate form in most of thecases In the literature different affinity sorbentswith a wide range of adsorption capacities for heavymetal ions have been reported Shreedhara-Murthyand Ryan found 5ndash27 mgg Cu(II) removal by cel-lulose dithiocarbamate resins [30] Roozemondshowed 32 mgg Cu(II) with pyrazole-containingpoly(styrene-divinyl-benzene) sorbents [31] Say etal [32] achieved 7141 4688 and 6394 mggadsorption capacities for Pb(II) Cr(III) and Cd(II)respectively with poly(HEMA-MAH) beads Karaet al [33] have prepared poly(EGDMA-VIM) beadsand found the chelation capacities of these beadswere 694 and 1148 mgg for Cd(II) and Pb(II)respectively Duran et al [34] have prepared [poly(VP-PEGMA-EGDMA)] beads and found the chela-

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

193

Figure 5 Effect of the initial pH of the testing solutions onthe adsorption capacity (Q) and percentage (R[]) for the tested metal ions Initial ion concen-tration = 100 mgL sample dose = 5 mg50 mLtemperature = 25degC and contact time = 24 h

Figure 6 Illustration of metalndashchelating resin complexes ofCo-Hyd Co-g-AP and the crosslinked chelatingresin

tion capacities of these beads were 1823 16501581 and 1825 mgg for Pb(II) Cd(II) Cr(III) andCu(II) respectively

33 Desorption of metal ions from thechelating resin

The repeated use of the resins is an essential param-eter in improving process economics Desorption ofmetal ions from resinndashmetal ion complexes wascarried out by HCl (02 M ) treatment at room tem-perature and the amount of metal ions desorbed in 1hour was measured As shown in Figure 7 morethan 96 of adsorbed metal ions are recovered inthe acid leaching process indicating that chelation(ie binding of heavy metal ions with functionalgroups in resin) is completely reversible In order toobtain the reusability of the resins chelationndashelu-tion cycle was repeated successfully five times byusing the same adsorbent and the results are shownin Figure 7

34 Dyes removalThe adsorption of dyes with the prepared chelatingresin beads was carried out by using three commer-cial azo dyes containing different functional groupssuch as ndashN=Nndash chlorine oxadiazine and sulfate(Figure 1) The results for the dyes adsorption areshown in Figure 8 The order for the dyes removalby the resins is Co-g-AP3gtCo-Hydgt poly(MMA-co-MA) indicating higher capacity for the cross -linked resin in comparison with the results obtained

for the unmodified copolymer This can be due topresence of network structure with different func-tional groups in the modified resin (Co-g-AP3)which can accommodate large molecules and inter-act with the functional groups present in the dyemolecules Also the relatively high adsorption per-centage of Co-Hyd resin can be due to highly poresstructure of this resin as shown in Figure 3c

4 ConclusionsAdsorption represents a potentially cost-effectiveway of eliminating toxic heavy metals from indus-trial wastewaters Reusable polymer-based adsor-bents have been recognized as a promising class oflow-cost adsorbents for the removal of heavy-metalions from aqueous waste streams In this study thereaction of AP and different crosslink agents withpoly(MMA-co-MA) led to the synthesis of signifi-cantly capable chelating resins for the removal ofheavy metal ions such as Cu2+ Cd2+ and Hg2+ fromaqueous solution These results suggest that the pre-pared chelating resin beads are good heavy metalions adsorbents in various pH values and can havegreat potential applications in environmental pro-tection The affinity order of metal ions on a molarbasis is as Cu2+gtCd2+gtHg2+ The new adsorbentshave higher adsorption properties than other adsor-bents reported by some researchers In addition thecapacity of dyes removal of the resin beads wasinvestigated and the results showed that the adsorbeddye increased by using crosslinked resin

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

194

Figure 7 Desorption of Hg2+ ion from the chelating resinsbeads that had been preadsorbed under condi-tions given in Figure 6 as a function of submer-sion time in 25 mL of HCl (02 M) solution for1 h at 25degC

Figure 8 Dyes removal efficiency by the prepared resinbeads (005 g of the chelating resin in 10 mLaqueous solution containing a dye with initialconcentration = 100 mgL at 25degC for 12 h with-out pH adjustment)

References [1] Matsuto T Jung C H Tanaka N Material and heavy

metal balance in a recycling facility for home electri-cal appliances Waste Management 24 425ndash436 (2004)DOI 101016jwasman200312002

[2] Srivastava N K Majumder C B Novel biofiltrationmethods for the treatment of heavy metals from indus-trial wastewater Journal of Hazardous Materials 1511ndash8 (2008)DOI 101016jjhazmat200709101

[3] Vaaramaa K Lehto J Removal of metals and anionsfrom drinking water by ion exchange Desalination155 157ndash170 (2003)DOI 101016S0011-9164(03)00293-5

[4] ernaacute M Use of solvent extraction for the removal ofheavy metals from liquid wastes Environmental Mon-itoring and Assessment 34 151ndash162 (1995) DOI 101007BF00546029

[5] Hu X Li Y Wang Y Li X Li H Liu X Zhang PAdsorption kinetics thermodynamics and isotherm ofthiacalix[4]arene-loaded resin to heavy metal ionsDesalination 259 76ndash83 (2010)DOI 101016jdesal201004032

[6] Al-Rashdi B A M Johnson D J Hilal N Removalof heavy metal ions by nanofiltration Desalination315 2ndash17 (2013)DOI 101016jdesal201205022

[7] Ozaki H Sharma K Saktaywin W Performance ofan ultra-low-pressure reverse osmosis membrane(ULPROM) for separating heavy metal effects of inter-ference parameters Desalination 144 287ndash294 (2002)DOI 101016S0011-9164(02)00329-6

[8] Peterskovaacute M Valderrama C Gibert O Cortina JL Extraction of valuable metal ions (Cs Rb Li U)from reverse osmosis concentrate using selective sor-bents Desalination 286 316ndash323 (2012)DOI 101016jdesal201111042

[9] Soleimani Lashkenari M Davodi B Ghorbani MEisazadeh H Use of core-shell polyanilinepoly-styrene nanocomposite for removal of Cr(VI) HighPerformance Polymers 24 345ndash355 (2012)DOI 1011770954008311436222

[10] Li L Li Y Luo X Deng J Yang W Helical poly(N-propargylamide)s with functional catechol groupsSynthesis and adsorption of metal ions in aqueoussolution Reactive and Functional Polymers 70 938ndash943 (2010)DOI 101016jreactfunctpolym201009006

[11] Jitjaicham S Kampalanonwat P Supaphol P Metaladsorption behavior of 24-dinitrophenyl hydrazinemodified polyacrylonitrile nanofibers Express Poly-mer Letters 7 832ndash841 (2013)DOI 103144expresspolymlett201380

[12] Co$kun R Soykan C Saccedilak M Removal of someheavy metal ions from aqueous solution by adsorptionusing poly(ethylene terephthalate)-g-itaconic acidacryl -amide fiber Reactive and Functional Polymers 66599ndash608 (2006)DOI 101016jreactfunctpolym200510012

[13] Sankar R Sasidaran M Kaliyappan T Synthesischaracterization thermal and chelation properties ofnew polymeric hydrazone based on 24-dihydroxy ben-zaldehyde High Performance Polymers 23 32ndash39(2011)DOI 1011770954008310381148

[14] Sasidaran M Sankar R Kandasamy P Vijayalak-shmi S Kaliyappan T Chelating and biological prop-erties of an azo polymer resin Synthesis characteriza-tion and its application High Performance Polymers23 602ndash609 (2011)DOI 1011770954008311428531

[15] Dinu M V Dragan E S Heavy metals adsorption onsome iminodiacetate chelating resins as a function ofthe adsorption parameters Reactive and FunctionalPolymers 68 1346ndash1354 (2008)DOI 101016jreactfunctpolym200806011

[16] Vasconcelos H L Faacutevere V T Gonccedilalves N SLaranjeira M C M Chitosan modified with ReactiveBlue 2 dye on adsorption equilibrium of Cu(II) andNi(II) ions Reactive and Functional Polymers 671052ndash1060 (2007)DOI 101016jreactfunctpolym200706009

[17] Takagi K Miwa S Yuki Y Synthesis of poly(tri-azinylstyrene) containing nitrogen-based ligand andfunction as metal ion adsorbent and oxidation catalystReactive and Functional Polymers 66 1718ndash1724(2006)DOI 101016jreactfunctpolym200607005

[18] Ahamed M E H Mbianda X Y Mulaba-BafubiandiA F Marjanovic L Ion imprinted polymers for theselective extraction of silver(I) ions in aqueous mediaKinetic modeling and isotherm studies Reactive andFunctional Polymers 73 474ndash483 (2013)DOI 101016jreactfunctpolym201211011

[19] Wang C-C Wang C-C Adsorption characteristics ofmetal complexes by chelated copolymers with aminogroup Reactive and Functional Polymers 66 343ndash356(2006)DOI 101016jreactfunctpolym200508011

[20] Vasconcelos H L Camargo T P Gonccedilalves N SNeves A Laranjeira M C M Faacutevere V T Chitosancrosslinked with a metal complexing agent Synthesischaracterization and copper(II) ions adsorption Reac-tive and Functional Polymers 68 572ndash579 (2008)DOI 101016jreactfunctpolym200710024

[21] Huang J Zhang K The high flux poly (m-phenyleneisophthalamide) nanofiltration membrane for dyepurification and desalination Desalination 282 19ndash26 (2011)DOI 101016jdesal201109045

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

195

tion capacities of these beads were 1823 16501581 and 1825 mgg for Pb(II) Cd(II) Cr(III) andCu(II) respectively

33 Desorption of metal ions from thechelating resin

The repeated use of the resins is an essential param-eter in improving process economics Desorption ofmetal ions from resinndashmetal ion complexes wascarried out by HCl (02 M ) treatment at room tem-perature and the amount of metal ions desorbed in 1hour was measured As shown in Figure 7 morethan 96 of adsorbed metal ions are recovered inthe acid leaching process indicating that chelation(ie binding of heavy metal ions with functionalgroups in resin) is completely reversible In order toobtain the reusability of the resins chelationndashelu-tion cycle was repeated successfully five times byusing the same adsorbent and the results are shownin Figure 7

34 Dyes removalThe adsorption of dyes with the prepared chelatingresin beads was carried out by using three commer-cial azo dyes containing different functional groupssuch as ndashN=Nndash chlorine oxadiazine and sulfate(Figure 1) The results for the dyes adsorption areshown in Figure 8 The order for the dyes removalby the resins is Co-g-AP3gtCo-Hydgt poly(MMA-co-MA) indicating higher capacity for the cross -linked resin in comparison with the results obtained

for the unmodified copolymer This can be due topresence of network structure with different func-tional groups in the modified resin (Co-g-AP3)which can accommodate large molecules and inter-act with the functional groups present in the dyemolecules Also the relatively high adsorption per-centage of Co-Hyd resin can be due to highly poresstructure of this resin as shown in Figure 3c

4 ConclusionsAdsorption represents a potentially cost-effectiveway of eliminating toxic heavy metals from indus-trial wastewaters Reusable polymer-based adsor-bents have been recognized as a promising class oflow-cost adsorbents for the removal of heavy-metalions from aqueous waste streams In this study thereaction of AP and different crosslink agents withpoly(MMA-co-MA) led to the synthesis of signifi-cantly capable chelating resins for the removal ofheavy metal ions such as Cu2+ Cd2+ and Hg2+ fromaqueous solution These results suggest that the pre-pared chelating resin beads are good heavy metalions adsorbents in various pH values and can havegreat potential applications in environmental pro-tection The affinity order of metal ions on a molarbasis is as Cu2+gtCd2+gtHg2+ The new adsorbentshave higher adsorption properties than other adsor-bents reported by some researchers In addition thecapacity of dyes removal of the resin beads wasinvestigated and the results showed that the adsorbeddye increased by using crosslinked resin

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

194

Figure 7 Desorption of Hg2+ ion from the chelating resinsbeads that had been preadsorbed under condi-tions given in Figure 6 as a function of submer-sion time in 25 mL of HCl (02 M) solution for1 h at 25degC

Figure 8 Dyes removal efficiency by the prepared resinbeads (005 g of the chelating resin in 10 mLaqueous solution containing a dye with initialconcentration = 100 mgL at 25degC for 12 h with-out pH adjustment)

References [1] Matsuto T Jung C H Tanaka N Material and heavy

metal balance in a recycling facility for home electri-cal appliances Waste Management 24 425ndash436 (2004)DOI 101016jwasman200312002

[2] Srivastava N K Majumder C B Novel biofiltrationmethods for the treatment of heavy metals from indus-trial wastewater Journal of Hazardous Materials 1511ndash8 (2008)DOI 101016jjhazmat200709101

[3] Vaaramaa K Lehto J Removal of metals and anionsfrom drinking water by ion exchange Desalination155 157ndash170 (2003)DOI 101016S0011-9164(03)00293-5

[4] ernaacute M Use of solvent extraction for the removal ofheavy metals from liquid wastes Environmental Mon-itoring and Assessment 34 151ndash162 (1995) DOI 101007BF00546029

[5] Hu X Li Y Wang Y Li X Li H Liu X Zhang PAdsorption kinetics thermodynamics and isotherm ofthiacalix[4]arene-loaded resin to heavy metal ionsDesalination 259 76ndash83 (2010)DOI 101016jdesal201004032

[6] Al-Rashdi B A M Johnson D J Hilal N Removalof heavy metal ions by nanofiltration Desalination315 2ndash17 (2013)DOI 101016jdesal201205022

[7] Ozaki H Sharma K Saktaywin W Performance ofan ultra-low-pressure reverse osmosis membrane(ULPROM) for separating heavy metal effects of inter-ference parameters Desalination 144 287ndash294 (2002)DOI 101016S0011-9164(02)00329-6

[8] Peterskovaacute M Valderrama C Gibert O Cortina JL Extraction of valuable metal ions (Cs Rb Li U)from reverse osmosis concentrate using selective sor-bents Desalination 286 316ndash323 (2012)DOI 101016jdesal201111042

[9] Soleimani Lashkenari M Davodi B Ghorbani MEisazadeh H Use of core-shell polyanilinepoly-styrene nanocomposite for removal of Cr(VI) HighPerformance Polymers 24 345ndash355 (2012)DOI 1011770954008311436222

[10] Li L Li Y Luo X Deng J Yang W Helical poly(N-propargylamide)s with functional catechol groupsSynthesis and adsorption of metal ions in aqueoussolution Reactive and Functional Polymers 70 938ndash943 (2010)DOI 101016jreactfunctpolym201009006

[11] Jitjaicham S Kampalanonwat P Supaphol P Metaladsorption behavior of 24-dinitrophenyl hydrazinemodified polyacrylonitrile nanofibers Express Poly-mer Letters 7 832ndash841 (2013)DOI 103144expresspolymlett201380

[12] Co$kun R Soykan C Saccedilak M Removal of someheavy metal ions from aqueous solution by adsorptionusing poly(ethylene terephthalate)-g-itaconic acidacryl -amide fiber Reactive and Functional Polymers 66599ndash608 (2006)DOI 101016jreactfunctpolym200510012

[13] Sankar R Sasidaran M Kaliyappan T Synthesischaracterization thermal and chelation properties ofnew polymeric hydrazone based on 24-dihydroxy ben-zaldehyde High Performance Polymers 23 32ndash39(2011)DOI 1011770954008310381148

[14] Sasidaran M Sankar R Kandasamy P Vijayalak-shmi S Kaliyappan T Chelating and biological prop-erties of an azo polymer resin Synthesis characteriza-tion and its application High Performance Polymers23 602ndash609 (2011)DOI 1011770954008311428531

[15] Dinu M V Dragan E S Heavy metals adsorption onsome iminodiacetate chelating resins as a function ofthe adsorption parameters Reactive and FunctionalPolymers 68 1346ndash1354 (2008)DOI 101016jreactfunctpolym200806011

[16] Vasconcelos H L Faacutevere V T Gonccedilalves N SLaranjeira M C M Chitosan modified with ReactiveBlue 2 dye on adsorption equilibrium of Cu(II) andNi(II) ions Reactive and Functional Polymers 671052ndash1060 (2007)DOI 101016jreactfunctpolym200706009

[17] Takagi K Miwa S Yuki Y Synthesis of poly(tri-azinylstyrene) containing nitrogen-based ligand andfunction as metal ion adsorbent and oxidation catalystReactive and Functional Polymers 66 1718ndash1724(2006)DOI 101016jreactfunctpolym200607005

[18] Ahamed M E H Mbianda X Y Mulaba-BafubiandiA F Marjanovic L Ion imprinted polymers for theselective extraction of silver(I) ions in aqueous mediaKinetic modeling and isotherm studies Reactive andFunctional Polymers 73 474ndash483 (2013)DOI 101016jreactfunctpolym201211011

[19] Wang C-C Wang C-C Adsorption characteristics ofmetal complexes by chelated copolymers with aminogroup Reactive and Functional Polymers 66 343ndash356(2006)DOI 101016jreactfunctpolym200508011

[20] Vasconcelos H L Camargo T P Gonccedilalves N SNeves A Laranjeira M C M Faacutevere V T Chitosancrosslinked with a metal complexing agent Synthesischaracterization and copper(II) ions adsorption Reac-tive and Functional Polymers 68 572ndash579 (2008)DOI 101016jreactfunctpolym200710024

[21] Huang J Zhang K The high flux poly (m-phenyleneisophthalamide) nanofiltration membrane for dyepurification and desalination Desalination 282 19ndash26 (2011)DOI 101016jdesal201109045

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

195

References [1] Matsuto T Jung C H Tanaka N Material and heavy

metal balance in a recycling facility for home electri-cal appliances Waste Management 24 425ndash436 (2004)DOI 101016jwasman200312002

[2] Srivastava N K Majumder C B Novel biofiltrationmethods for the treatment of heavy metals from indus-trial wastewater Journal of Hazardous Materials 1511ndash8 (2008)DOI 101016jjhazmat200709101

[3] Vaaramaa K Lehto J Removal of metals and anionsfrom drinking water by ion exchange Desalination155 157ndash170 (2003)DOI 101016S0011-9164(03)00293-5

[4] ernaacute M Use of solvent extraction for the removal ofheavy metals from liquid wastes Environmental Mon-itoring and Assessment 34 151ndash162 (1995) DOI 101007BF00546029

[5] Hu X Li Y Wang Y Li X Li H Liu X Zhang PAdsorption kinetics thermodynamics and isotherm ofthiacalix[4]arene-loaded resin to heavy metal ionsDesalination 259 76ndash83 (2010)DOI 101016jdesal201004032

[6] Al-Rashdi B A M Johnson D J Hilal N Removalof heavy metal ions by nanofiltration Desalination315 2ndash17 (2013)DOI 101016jdesal201205022

[7] Ozaki H Sharma K Saktaywin W Performance ofan ultra-low-pressure reverse osmosis membrane(ULPROM) for separating heavy metal effects of inter-ference parameters Desalination 144 287ndash294 (2002)DOI 101016S0011-9164(02)00329-6

[8] Peterskovaacute M Valderrama C Gibert O Cortina JL Extraction of valuable metal ions (Cs Rb Li U)from reverse osmosis concentrate using selective sor-bents Desalination 286 316ndash323 (2012)DOI 101016jdesal201111042

[9] Soleimani Lashkenari M Davodi B Ghorbani MEisazadeh H Use of core-shell polyanilinepoly-styrene nanocomposite for removal of Cr(VI) HighPerformance Polymers 24 345ndash355 (2012)DOI 1011770954008311436222

[10] Li L Li Y Luo X Deng J Yang W Helical poly(N-propargylamide)s with functional catechol groupsSynthesis and adsorption of metal ions in aqueoussolution Reactive and Functional Polymers 70 938ndash943 (2010)DOI 101016jreactfunctpolym201009006

[11] Jitjaicham S Kampalanonwat P Supaphol P Metaladsorption behavior of 24-dinitrophenyl hydrazinemodified polyacrylonitrile nanofibers Express Poly-mer Letters 7 832ndash841 (2013)DOI 103144expresspolymlett201380

[12] Co$kun R Soykan C Saccedilak M Removal of someheavy metal ions from aqueous solution by adsorptionusing poly(ethylene terephthalate)-g-itaconic acidacryl -amide fiber Reactive and Functional Polymers 66599ndash608 (2006)DOI 101016jreactfunctpolym200510012

[13] Sankar R Sasidaran M Kaliyappan T Synthesischaracterization thermal and chelation properties ofnew polymeric hydrazone based on 24-dihydroxy ben-zaldehyde High Performance Polymers 23 32ndash39(2011)DOI 1011770954008310381148

[14] Sasidaran M Sankar R Kandasamy P Vijayalak-shmi S Kaliyappan T Chelating and biological prop-erties of an azo polymer resin Synthesis characteriza-tion and its application High Performance Polymers23 602ndash609 (2011)DOI 1011770954008311428531

[15] Dinu M V Dragan E S Heavy metals adsorption onsome iminodiacetate chelating resins as a function ofthe adsorption parameters Reactive and FunctionalPolymers 68 1346ndash1354 (2008)DOI 101016jreactfunctpolym200806011

[16] Vasconcelos H L Faacutevere V T Gonccedilalves N SLaranjeira M C M Chitosan modified with ReactiveBlue 2 dye on adsorption equilibrium of Cu(II) andNi(II) ions Reactive and Functional Polymers 671052ndash1060 (2007)DOI 101016jreactfunctpolym200706009

[17] Takagi K Miwa S Yuki Y Synthesis of poly(tri-azinylstyrene) containing nitrogen-based ligand andfunction as metal ion adsorbent and oxidation catalystReactive and Functional Polymers 66 1718ndash1724(2006)DOI 101016jreactfunctpolym200607005

[18] Ahamed M E H Mbianda X Y Mulaba-BafubiandiA F Marjanovic L Ion imprinted polymers for theselective extraction of silver(I) ions in aqueous mediaKinetic modeling and isotherm studies Reactive andFunctional Polymers 73 474ndash483 (2013)DOI 101016jreactfunctpolym201211011

[19] Wang C-C Wang C-C Adsorption characteristics ofmetal complexes by chelated copolymers with aminogroup Reactive and Functional Polymers 66 343ndash356(2006)DOI 101016jreactfunctpolym200508011

[20] Vasconcelos H L Camargo T P Gonccedilalves N SNeves A Laranjeira M C M Faacutevere V T Chitosancrosslinked with a metal complexing agent Synthesischaracterization and copper(II) ions adsorption Reac-tive and Functional Polymers 68 572ndash579 (2008)DOI 101016jreactfunctpolym200710024

[21] Huang J Zhang K The high flux poly (m-phenyleneisophthalamide) nanofiltration membrane for dyepurification and desalination Desalination 282 19ndash26 (2011)DOI 101016jdesal201109045

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

195

[22] Teng M-Y Lin S-H Removal of methyl orange dyefrom water onto raw and acidactivated montmoril-lonite in fixed beds Desalination 201 71ndash81 (2006)DOI 101016jdesal200603521

[23] Yan B Wang Q Covalently bonded assembly andphotoluminescent properties of rare earthsilicapoly(methyl methacrylate-co-maleic anhydride) hybridmaterials Journal of Photochemistry and Photobiol-ogy A Chemistry 197 213ndash219 (2008)DOI 101016jjphotochem200712025

[24] El-Hag Ali A Shawky H A Abd El Rehim H AHegazy E A Synthesis and characterization ofPVPAAc copolymer hydrogel and its applications inthe removal of heavy metals from aqueous solutionEuropean Polymer Journal 39 2337ndash2344 (2003)DOI 101016S0014-3057(03)00150-2

[25] Albunia A R Rizzo P Guerra G Torres F J Cival-leri B Zicovich-Wilson C M Uniplanar orientationsas a tool to assign vibrational modes of polymer chainMacromolecules 40 3895ndash3897 (2007)DOI 101021ma070380+

[26] Wang C-C Chang C-Y Chen C-Y Study on metalion adsorption of bifunctional chelatingion-exchangeresins Macromolecular Chemistry and Physics 202882ndash890 (2001)DOI 1010021521-3935(20010301)2026lt882AID-

MACP882gt30CO2-K[27] Dinu M V Dragan E S Evaluation of Cu2+ Co2+

and Ni2+ ions removal from aqueous solution using anovel chitosanclinoptilolite composite Kinetics andisotherms Chemical Engineering Journal 160 157ndash163 (2010)DOI 101016jcej201003029

[28] Murugesan A Ravikumar L SathyaSelvaBala VSenthilKumar P Vidhyadevi T Dinesh Kirupha SKalaivani S S Krithiga S Sivanesan S Removal ofPb(II) Cu(II) and Cd(II) ions from aqueous solutionusing polyazomethineamides Equilibrium and kineticapproach Desalination 271 199ndash208 (2011)DOI 101016jdesal201012029

[29] Chaisuwan T Komalwanich T Luangsukrerk SWongkasemjit S Removal of heavy metals frommodel wastewater by using polybenzoxazine aerogelDesalination 256 108ndash114 (2010)DOI 101016jdesal201002005

[30] Shreedhara-Murthy R S Ryan D E Preconcentra-tion of copper cadmium mercury and lead from seaand tap water samples on a dithiocarbamatecellulosederivative Analytica Chimica Acta 140 163ndash169(1982)DOI 101016S0003-2670(01)95461-3

[31] Roozemond D A den Hond F Veldhuis J B JStrasdeit H Driessen W L Preferred uptake of Cu(II)and Cd(II) by novel pyrazole-functionalized chelatingpolymers European Polymer Journal 24 867ndash872(1988)DOI 1010160014-3057(88)90161-9

[32] Say R Garipcan B Emir S Patır S Denizli APreparation and characterization of the newly synthe-sized metal-complexing-ligand N-methacryloylhisti-dine having PHEMA beads for heavy metal removalfrom aqueous solutions Macromolecular Materialsand Engineering 287 539ndash545 (2002)DOI 1010021439-2054(20020801)2878lt539AID-

MAME539gt30CO2-O[33] Kara A Uzun L Be$irli N Denizli A Poly(ethylene

glycol dimethacrylate-n-vinyl imidazole) beads forheavy metal removal Journal of Hazardous Materials106 93ndash99 (2004)DOI 101016jjhazmat200308016

[34] Duran A Soylak M Tuncel S A Poly(vinyl pyri-dine-poly ethylene glycol methacrylate-ethylene gly-col dimethacrylate) beads for heavy metal removalJournal of Hazardous Materials 155 114ndash120 (2008)DOI 101016jjhazmat200711037

Masoumi and Ghaemy ndash eXPRESS Polymer Letters Vol8 No3 (2014) 187ndash196

196