Desalination 266 (2011) 108–113

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Desalination

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Flocculation activity of novel ferric chloride–polyacrylamide (FeCl3-PAM)hybrid polymer

Khai Ern Lee, Tjoon Tow Teng ⁎, Norhashimah Morad, Beng Teik Poh, Mohanapriya MahalingamSchool of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia

⁎ Corresponding author. Tel.: +604 6532215; fax: +E-mail address: ttteng@usm.my (T.T. Teng).

0011-9164/$ – see front matter © 2010 Elsevier B.V. Adoi:10.1016/j.desal.2010.08.009

a b s t r a c t

a r t i c l e i n f o

Article history:Received 30 May 2010Received in revised form 5 August 2010Accepted 5 August 2010Available online 9 September 2010

Keywords:Hybrid polymerFerric chloridePolyacrylamideKaolin suspensionDye wastewaterFlocculation

A ferric chloride–polyacrylamide inorganic–organic hybrid polymer has been synthesized using a ferric chloride/polyacrylamide ratio of 1:1 via free radical solution polymerization. A redox initiation system - (NH4)2S2O8 andNaHSO3was used to initiate the polymerization at 50 °C in aqueousmedium. The ferric chloride–polyacrylamidehybrid polymer was characterized using Fourier transform infrared (FT-IR) spectrometer to determine theirfunctional groups in the hybrid polymer chain. The FeCl3-PAM hybrid polymer was tested for flocculatingactivities on kaolin suspension and Terasil Red R dyewastewater. Parameters such as solution pH and FeCl3-PAMhybrid polymer dosage have been studied. One-way ANOVA shows that pH has a significant impact (pb0.05) inflocculating both kaolin suspension and Terasil Red Rwastewater. The results showaminimumdosage of 2 mg/Lis able to removemore than 99% of turbidity in kaolin suspension at pH 2. FeCl3-PAMhybrid polymer also showsits capability inflocculatingTerasil RedR dyewastewater. It is able to reduce 89% of COD and99% of colour at pH5using 500 mg/L of dosage.

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© 2010 Elsevier B.V. All rights reserved.

1. Introduction

Coagulation–flocculation of colloidal suspensions appears as animportant process in industrial wastewater treatment. Coagulation ofdissolved and colloidal substances in wastewater is essentiallyunderstood in light of Derjaguin–Landau–Verwey–Overbeek theory(DLVO theory) [1]. Coagulation decreases and neutralizes the surfacecharge of suspended particles by using inorganic salts such asaluminium and ferric salts [1]. Flocculation plays a major role aswell in the fate and transport of contaminants in aquatic environ-ments by bringing the aggregated flocs to form large agglomerates inthe presence of polymers [1,2].

Ferric salts such as ferric chloride has been extensively used as acoagulant whether solely or associated with flocculants in coagula-tion–flocculation system [3–5]. Ferric chloride is able to form strongerand heavier flocs over a broader pH range and it is less sensitivecompared to alum on the problems of filtrate quality upon instancesof overdosing [6]. Acrylamide-based polymers have received a greatextent of utility in industry due to its high molecular weight andwater-soluble property. It often acts as a flocculant in separating theaggregated colloids from the water phase [7,8]. In recent years,various flocculants have been developed including inorganic floccu-lants, organic flocculants and composite as well as hybrid flocculants.Due to the superior efficiency of hybrid flocculants compared with

conventional inorganic flocculants, and its lower cost compared to theorganic flocculants, hybrid flocculants have been extensively studiedand applied to water and wastewater treatment system recently [9].

An addition of inorganic salts to the organic flocculants wassuggested as the main method to prepare hybrid-flocculatingpolymers [10]. The goal of this method is to enhance the aggregatingpower of flocculants by increasing the ratio of effective componentand positive charge of flocculants [11]. Due to the synergistic effect oftwo components in one material, these inorganic–organic hybridpolymers have become attractive materials in wastewater treatmentwith its high performance [10,11]. Apart from that, hybrid polymersrequire only one operation, which is flocculation instead of conven-tional two operating vessels in coagulation–flocculation system.Reduction of operation time due to the application of these hybridpolymers in a single operation vessel would be cost effective and it isfavorable to the industries that produce a large volume of wastewaterdischarge.

Kaolin clay production is one of the important mineral industries;its wastewater often poses a problem for waste tailing treatment,hydrometallurgical, and mineral processing operations due to itscolloidal size and permanently negatively charged basal faces thatlead to difficulty in settling and consolidation [12]. Disperse dye suchas Terasil Red R is exclusively used for synthetic fibers, polyester,polyamides (nylon) and acrylic fibers dyeing in the textile industries.It is almost relatively insoluble in water and appears as a finedispersion in water [13]. Both kaolin processing wastewater anddisperse dye wastewater share the common problemwhere they tendto disperse in water and normally come in a large volume due to their

Table 1Characteristics of the 300 mg/L kaolin suspension.

Parameters Value

Turbidity (NTU) 378–417pH 3.75–4.54

109K.E. Lee et al. / Desalination 266 (2011) 108–113

highly water-intensive processes. Kaolin processing often contributesto a high turbidity in the wastewater and the reduction of turbidityfrom the effluents has become a problem encountered by the clayprocessing industry [14]. Therefore, turbidity has become a crucialparameter in evaluating the water quality of the kaolin processingeffluent. Disperse dyestuffs in the effluents from industries such astextile industry is contributing to high colour content and COD. Thehigh colour density and COD content in the dyewastewater need to beinvestigated due to adverse aesthetic effects and the wastewater ifuntreated can be carcinogenic, mutagenic and generally detrimentalto our environment [15]. Hence, both kaolin processing wastewaterand disperse dye wastewater need to be treated before discharged tothe environment.

In this study, a newhybridflocculant ferric chloride–polyacrylamide(FeCl3-PAM) hybrid polymer has been developed to treat kaolinsuspension and synthetic dye (Terasil Red R) wastewater. Ferricchloride–polyacrylamide (FeCl3-PAM) hybrid polymer was synthesizedvia free radical solution polymerization. FT-IR was used to characterizethe hybrid polymer. The flocculation activities on kaolin suspension andsynthetic dye wastewater (Terasil Red R) were studied to determine itsoptimal operating conditions.

2. Materials and methods

2.1. Materials

Acrylamide (N98% purity) was obtained from Fluka, whereas ferricchloride (N99.5% purity) was obtained from Systerm. Ammoniumpersulphate (AR, Systerm) and sodium hydrogen sulphite (GR, AcrosOrganics) were used as redox initiators.

2.2. Synthesis of hybrid polymer

A 500 mL three-necked reaction flask equipped with a refluxcondenser, a thermostatic stirring water bath, and a rubber septumcap were set up for the polymerization reaction. The temperature ofthe thermostatic stirring water bath was controlled at 50 °C. 1.0 M ofacrylamide (7.108 g in 100 mL of deionized water) was transferredinto the reaction flask and thoroughly stirred. Nitrogen gas waspurged into the reaction medium for 30 min to deoxygenate thereaction medium before polymerization took place. 4.6 mg ofammonium persulphate and 0.52 mg of sodium hydrogen sulphitewere added into the reactionmedium as redox initiators to initiate thepolymerization [7,10]. The polymerization took place for 2 h, anequivalent mole ratio of ferric chloride was then added into the flask.The mixture was blended under nitrogen atmosphere for 4 h until itwas homogenous. The FeCl3-PAM hybrid polymer obtained was in agel form and it was precipitated with acetone to remove non-reactedacrylamide. The hybrid polymer was then vacuum dried andgrounded into powder.

2.3. Fourier transform infrared (FT-IR) spectra analysis

The chemical compositions of the hybrid polymerswere determinedusing Avatar 360 FT-IR spectrophotometer. The FeCl3-PAM hybridpolymers were prepared into platelets with potassium bromide. Thesamples were tested after completion of the blank spectrum scanning.The FT-IR equipment was operated with a resolution of 4 cm−1 andscanning range from 4000 to 400 cm−1.

2.4. Kaolin suspension flocculation

The FeCl3-PAM hybrid polymer was used to flocculate a kaolinsuspension. A 300 mg/L concentration of kaolin suspension wasprepared [16]. The kaolin suspension turbidity was within the rangeof industrial effluent and the common studied range reported by other

researchers. The pH of the kaolin suspension was adjusted using 0.1MHCl and 0.1M NaOH. Flocculation was carried out using a standard jartest apparatus. The FeCl3-PAM hybrid polymer solutions were thenadded into the beakers that contained kaolin suspension to initiateflocculation. The mixture was stirred at a rapid speed of 200 rpm for3 min to disperse the FeCl3-PAM hybrid polymer in the kaolinsuspension followed by a slow mix of 100 rpm for 6 min to ensure athorough surface interaction between kaolin and the FeCl3-PAMhybrid polymer and to facilitate agglomeration of flocs. Flocs wereformed and allowed to settle for 30 min. The turbidity of thesupernatant was measured with a HACH 2100P turbidity meteraccording to APHA [17]. Table 1 shows the characteristics of the kaolinsuspension.

Turbidity reduction was calculated as follows:

Turbidity reduction %ð Þ = Initial Turbidity–Final TurbidityInitial Turbidity

× 100 ð1Þ

2.5. Dye wastewater flocculation

Synthetic dye wastewater was prepared using a commercialdisperse dye Terasil Red R. A concentration of 200 mg/L dispersedye Terasil Red R wastewater sample was prepared which was withinthe range of industrial effluent and the common studied rangereported by other researchers [18]. Table 2 shows the chemicalcharacteristics of Terasil Red R wastewater. The COD measurementwas performed according to APHA [17].

The COD reduction efficiency was calculated as follows:

Percentage of COD reduction =Mi–Mf

Mi× 100 ð2Þ

where

Mi is the initial COD content (mg/L)Mf is the final COD content (mg/L)

The colour content was measured according to APHA (2005) [17].The colour removal efficiency was calculated as follows:

Percentage of colour removal =Ci–Cf

Ci× 100 ð3Þ

where

Ci is the initial colour concentration (PtCo)Cf is the final colour concentration (PtCo)

3. Results and discussion

3.1. Fourier transform infrared (FT-IR) spectra analysis

The compositions and functional groups of the FeCl3-PAM hybridpolymer were determined by FT-IR spectrophotometer. The FT-IRspectra in Fig. 1 show the peaks of FeCl3-PAM hybrid polymer. A highpeak of primary amine -NH2 (m) was observed at 3376 cm−1, twosharp peaks were observed for primary amide(s) and -CO-NH2 at

Table 2Characteristics of the 200 mg/L Terasil Red R wastewater.

Parameters Value

pH 5.85–5.95COD (mg/L) 278–412Colour point (PtCo) 3860–4320

95

96

97

98

99

100

2 4 6 8 10 12

pH

Tu

rbid

ity

Red

uct

ion

(%

)

0

2

4

6

8

10

12

14

Fin

al T

urb

idit

y (N

TU

)

Turbidity Reduction (%)Final Turbidity (NTU)

Fig. 2. Effect of pH (2 to 12) on kaolin turbidity reduction using FeCl3-PAM hybridpolymer.

110 K.E. Lee et al. / Desalination 266 (2011) 108–113

1635 cm−1 and 1403 cm−1 respectively. A low peak of -C-NH2 wasobserved at 1112 cm−1 and a broad and lowpeakwas found for C-Cl at671 cm−1. Based on the functional groups elucidated in the spectra,Cl− from FeCl3 has a relatively weak bonding with the polyacrylamidechain where it indicates that FeCl3 is attached on the polyacrylamidechain. Hence, elucidation of FT-IR spectra confirms that the FeCl3-PAMhybrid polymer is successfully synthesized and the FeCl3-PAM hybridpolymer forms an inorganic–organic complex.

3.2. Flocculation of kaolin suspension

3.2.1. Effect of pHIn the flocculation of kaolin suspension, pH plays an important role

in determining the efficiency of turbidity reduction. Kaolin suspensionflocculation only happens within a specific pH range using differentflocculants. Fig. 2 shows the effect of pH (2 to 12) on turbidityreduction of kaolin suspension using FeCl3-PAM hybrid polymer. Theresult shows the turbidity reduction decreases as the pH increasesfrom 2 to 8. At pH 2, it gives the best flocculation efficiency, which is99% as the kaolin surface charge was near zero [19]. The FeCl3-PAMhybrid polymer becomes an ionized state at pH 2, the ionized Fe3+ caneasily neutralize charge residual on the kaolin surface and theexpanding chain therefore can easily bridge the kaolin particles[19]. The negative charge on the kaolin surface increases with pH andthis causes the repulsion between kaolin particles and thus lowers theflocculation efficiency as the polymer chains are less extended and the

Fig. 1. FT-IR spectra for FeCl

distance to be bridged between kaolin particles is larger. The turbidityreduction of kaolin increases after pH 8 probably because the Fe(OH)3-PAM complex start to form in the alkaline region of pH 10 to 12and this leads to the adsorption of Fe(OH)3-PAM hybrid polymercompound onto the kaolin surfaces.

A statistical approach was used to compare the effect of pH inreducing turbidity. One-way ANOVA procedure depicts a one-wayanalysis of variances for a quantitative dependent variable by a singlefactor (turbidity reduction) and it was used to test the hypothesismeans of the turbidity reduction [8]. The one-way ANOVA test wasfound to have a significant difference (pb0.05) between pH. Theturbidity reduction shows that differences exist among the means.Post hoc range test and pairwise multiple comparisons were used todetermine which means differ. Tukey comparison was used tocompare the turbidity reduction with equal group variances. TheTukey comparisons of pH on turbidity reduction are shown in Table 3.

3-PAM hybrid polymer.

Table 3The Tukey comparisons of the pH for the turbidity reduction.

(I) pH (J) pH p value (I) pH (J) pH p value (I) pH (J) pH p value

2 4 0.061 4 2 0.061 6 2 0.026⁎

6 0.026⁎ 6 0.995 4 0.9958 0.000⁎ 8 0.006⁎ 8 0.015⁎

10 0.000⁎ 10 0.021⁎ 10 0.048⁎

12 0.003⁎ 12 0.529 12 0.8068 2 0.000⁎ 10 2 0.000⁎ 12 2 0.003⁎

4 0.006⁎ 4 0.021⁎ 4 0.5296 0.015⁎ 6 0.048⁎ 6 0.806

10 0.978 8 0.978 8 0.11612 0.116 12 0.330 10 0.330

⁎ Significant (pb0.05).

Table 4Comparison of supernatant pH before and after flocculation.

Initial pH pH after flocculation Difference in pH

1.0 0.88 −0.121.5 1.42 −0.082.0 2.12 0.122.5 2.66 0.163.0 3.20 0.203.5 3.78 0.28

111K.E. Lee et al. / Desalination 266 (2011) 108–113

There are significant differences (pb0.05) between pH whereby pH 2which is the optimal pH in flocculating kaolin suspension has asignificant difference with pH 6 to 12 on turbidity reduction.

The kaolin tetrahedral face sheet carries a permanent negativecharge and it varies depending on solution pH [20]. FeCl3 hybridpolymer was found to be effective in flocculating kaolin suspension inlower pH range. At pH≤2, the charge is positive. The negative chargeof the surface is reduced at low pH and thus it improves theflocculation efficiency. Hence, experiments were then carried out inlow pH range from pH 1.0 to 3.5 to determine the optimumflocculation pH for kaolin suspension. Fig. 3 shows the highestflocculation efficiency occurs at pH 2 and this is in agreement with thefinding of Besra et al. [19]. Kaolin becomes positively charged atpHb2. As the pH increases it carries a net negative charge on thesurface. The reversal of charge from negative to positive occurs at apH≤2. At pH 2 where the kaolin surface charge is near zero, kaolinparticles have the least repulsion between each other, hence theturbidity reduction was found to be 99%. The collapse of electricaldouble layer allows particles to be brought close enough by van derWaals forces to bond particles into larger aggregates, and flocculationis induced by FeCl3-PAM hybrid polymer [21].

3.2.2. Mechanism of kaolin flocculationAs mentioned in the previous section, kaolin suspension floccu-

lation depends on pH. Eq. (4) is believed to be the mechanism forFeCl3-PAM hybrid polymer being ionized when it was dosed into thekaolin suspension. In acidic medium with pHb2, FeCl3-PAM hybridpolymer was ionized to become [Fe3+ · 3Cl−]-PAM. The [Fe3+ ·3Cl−]-PAM was bridged on the kaolin surface (SOH) and released theCl− ions to form HCl as per Eq. (5) [22]. Release of HCl to the

98.80

99.00

99.20

99.40

99.60

99.80

100.00

1.0

pH

Tu

rbid

ity

Red

uct

ion

(%

)

0

1

2

3

Fin

al T

urb

idit

y (N

TU

)

Turbidity Reduction (%)Final Turbidity (NTU)

3.53.02.52.01.5

Fig. 3. Effect of pH (1 to 3.5) on kaolin turbidity reduction using FeCl3-PAM hybridpolymer.

supernatant made the pH of the supernatant drop to below its initialpH after flocculation. This is shown in Table 4. The final pH ofsupernatant dropped below the initial pH of 1 and 1.5 afterflocculation.

3SOHþ FeCl3 � PAM þ Hþ↔3SOH þ ½Fe3þ�3Cl−� � PAM þ H

þ ð4Þ

3SOHþ ½Fe3þ�3Cl�� � PAM þ Hþ↔3ðSO−Þ�Fe3þ � PAM þ 3HCl þ H

þ

ð5ÞAs the initial pH increased beyond 2, the negative charge on kaolin

surfacewas enhancedbyOH− ions (Eq. (6)). The charge neutralization ofthe ionized [Fe3+ · 3Cl−]-PAM hybrid polymer with negatively chargedkaolin surface (SOH) took place and released H2O to the supernatantaccording to Eq. (7). The final pH of the supernatant was higher than theinitial pH after flocculation for pH≥2 as the H2O molecules wereproduced afterflocculation. The increase in the difference between initialand final pH as the initial pH increased in Table 4 is due to the H2Omolecules produced in the supernatant and the pH moving towardsneutral [19,22].

3SOH þ FeCl3 � PAM þ 3OH−↔3SOH þ ½Fe3þ�3Cl−� � PAM þ 3OH

−

ð6Þ

3SOH þ ½Fe3þ�3Cl−� � PAM þ 3OH−↔3ðSO−Þ�Fe3þ � PAM þ 3H2O

ð7Þ

3.2.3. Effect of FeCl3-PAM hybrid polymer dosageThe study of the effect of the FeCl3-PAM hybrid polymer dosage on

the turbidity reduction has been undertaken by varying the dosage ofFeCl3-PAM hybrid polymer in the kaolin suspension. The pH was keptat 2. The results are shown in Fig. 4. Different dosages (1 to 6 mg/L) ofFeCl3-PAM hybrid polymer were used to flocculate kaolin suspension.The turbidity reduction was shown to increase with dosage of FeCl3-PAM hybrid polymer. It is evident that to reduce more than 99% ofkaolin suspension, a minimum dosage of 2 mg/L is required. The

97.50

98.00

98.50

99.00

99.50

100.00

1 2 3 4 5 6

Dosage (mg/L)

Tu

rbid

ity

Red

uct

ion

(%

)

0

1

2

3

4

5

6

Fin

al T

urb

idit

y (N

TU

)

Turbidity Reduction (%)

Final Turbidity (NTU)

Fig. 4. Effect of FeCl3-PAM hybrid polymer dosage on kaolin turbidity reduction.

0.0

20.0

40.0

60.0

80.0

100.0

2.0 4.0 6.0 8.0 10.0 12.0

pH

Per

cen

tag

e (%

)COD Reduction(%)

ColourRemoval (%)

Fig. 5. Effect of pH (2.0 to 12.0) on COD reduction and colour removal using FeCl3-PAMhybrid polymer.

60.0

65.0

70.0

75.0

80.0

85.0

90.0

95.0

100.0

200 300 400 500 600 700

Dosage (mg/L)

Per

cen

tag

e (%

)

COD Reduction (%)

Colour Removal (%)

Fig. 7. Effect of dosage of FeCl3-PAM hybrid polymer on COD reduction and colourremoval.

112 K.E. Lee et al. / Desalination 266 (2011) 108–113

turbidity reduction rate forms a plateau beyond dosage of 4 mg/L. Thisis probably because almost all the kaolin particles that accounted forthe turbidity had been removed at that stage. Further increase in theFeCl3-PAM hybrid polymer dosage did not produce a better turbidityreduction rate.

3.3. Flocculation of dye wastewater

3.3.1. Effect of pHThe removal of a 200 mg/L synthetic Terasil RedRdyewastewaterby

FeCl3-PAM hybrid polymer has been studied at various pH. By varyingthe solution pH, the optimum pH ranges corresponding to the highestpercentage COD reduction and colour removal of dye solution can bedetermined. Fig. 5 is a plot of the COD reduction and colour removal vs.the pH of the Terasil Red R dye wastewater. Dye solution pHwas variedfrom 2 to 12. COD reduction and colour removal were found to beeffective between pH of 4 to 5 which is in agreement with the results ofKim et al. and Aziz et al. [23,24]. The COD reduction and colour removalefficiencies dropped as the pH increased beyond this range. When thealkalinity of the solution containing FeCl3-PAM hybrid polymerincreases, Fe(OH)3-PAM complex starts to form. This could be due tothe formation of iron hydroxide precipitate that can be expected at pHvalues higher than 6. This is related to its solubility product given byEq. (8).

Ksp ¼ ½Fe3þ�:½OH−�3 ð8Þ

where Ksp is the solubility constant of the ferric hydroxide. Increase in

60.0

65.0

70.0

75.0

80.0

85.0

90.0

95.0

100.0

3.5 4.0 4.5 5.0 5.5 6.0

pH

Per

cen

tag

e (%

)

COD Reduction (%)

Colour Removal (%)

Fig. 6. Effect of pH (3.5 to 6) on COD reduction and colour removal using FeCl3-PAMhybrid polymer.

Fe3+ ion or OH− ion concentration beyond the Ksp value favors theformation of the hydroxide, Fe(OH)3 [25]. Further study on pH effect byzooming into the pH range between 3.5 and 6.0 shows that in the pHrange of 4.0 to 5.5, a good flocculation occurred. This is depicted in Fig. 6with 89% of COD reduction and 99% of colour removal at pH 5. Beyondthis pH, the COD reduction and colour removal show lower rates. Thisphenomenon is due to the increase in solubility of iron complex.According to Stephenson and Duff [6], the effect of pH on chemicalcoagulation/floccculation may be considered as a balance of twocompetitive forces: (1) between H+ and metal hydrolysis products forinteraction with organic ligands and (2) between hydroxide ions andorganic anions for interaction with metal hydrolysis products.

3.3.2. Effect of hybrid polymer dosageThe COD reduction and colour removalwere studied by varying the

amount of polymerdosage in the solution at pH5 inflocculating TerasilRed R dye wastewater. Fig. 7 shows the effect of dosage of FeCl3-PAMhybrid polymer on COD reduction and colour removal. 89% of CODreduction and 99% of colour removal were the highest rates using500 mg/L. Beyond 500 mg/L, the colour removal became constant andformed plateau. Further increase in FeCl3-PAMhybrid polymer dosagedid not produce a better removal rate, as almost all the dyes wereremoved at this stage. The COD reduction began to decrease slightlywith further increase in FeCl3-PAM hybrid polymer dosage. Thisphenomenon can be attributed to excess of FeCl3-PAMhybrid polymerthat contains organic compound that contributes to the COD content ofthe supernatant. The removal of colour and COD ismainly attributed tothe formation of precipitates from the combination of the solubleorganics and the coagulant [26]. The final COD content in thesupernatant using 500 mg/L of FeCl3-PAM hybrid polymer was44 mg/L which complies with the Standard B of the MalaysianEnvironmental Quality Act 1974 (100 mg/L for COD). A correlationbetween COD reduction and colour removal by FeCl3-PAM hybridpolymer is given in Table 5. A significant correlation between CODreduction and colour removalwas reported. This indicates the increaseof colour removal will increase the COD reduction.

Table 5Correlation of COD reduction and colour removal by FeCl3-PAM hybrid polymer.

COD reduction Colour removal

COD reduction Pearson correlation 1 .882⁎

p value (2-tailed) . .020n 6 6

Colour removal Pearson correlation .882⁎ 1p value (2-tailed) .020 .n 6 6

⁎ significant (pb0.05).

113K.E. Lee et al. / Desalination 266 (2011) 108–113

4. Conclusion

FeCl3-PAM hybrid polymer of ratio of 1:1 has been successfullysynthesized in this study using free radical polymerization method.Characterization of FeCl3-PAM hybrid polymer has been done usingFourier transform infrared spectrometer (FT-IR) to determine itsfunctional groups in the hybrid polymer chain. It forms an inorganic–organic complex. The FeCl3-PAM hybrid polymer was used inflocculating kaolin suspension and Terasil Red R dye wastewater. TheFeCl3-PAMhybrid polymerwas able to remove N99% of turbidity at pH2using a minimum dosage of 2 mg/L. Flocculation of Terasil Red R dyewastewater was done in this study, the removal rate of 89% in COD and99% in colour was obtained at pH 5 using 500 mg/L dosage. The finalCOD content in the supernatant was 44 mg/L that complies with theStandard B of theMalaysian Environmental Quality Act 1974 and FeCl3-PAM hybrid polymer has been shown to be an effective flocculatingagent.

Acknowledgement

The authors wish to acknowledge the USM postgraduate fellow-ship provided by Universiti Sains Malaysia that has resulted in thisstudy.

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