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Removal of Suspended Colloids through the Control ofTheir Zeta PotentialHossein Moayedi a , Sina Kazemian b , Khairul Anuar Kassim a , Ramli Nazir a & Mendi Raftaria

a Department of Geotechnics & Transportation, Faculty of Civil Engineering , UniversitiTeknologi Malaysia , Johor , Malaysiab Department of Civil Engineering , Payame Noor University , Tehran , IranAccepted author version posted online: 18 Oct 2012.Published online: 24 Aug 2013.

To cite this article: Hossein Moayedi , Sina Kazemian , Khairul Anuar Kassim , Ramli Nazir & Mendi Raftari (2013) Removalof Suspended Colloids through the Control of Their Zeta Potential, Journal of Dispersion Science and Technology, 34:9,1273-1279, DOI: 10.1080/01932691.2012.738113

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Removal of Suspended Colloids through the Controlof Their Zeta Potential

Hossein Moayedi,1 Sina Kazemian,2 Khairul Anuar Kassim,1 Ramli Nazir,1

and Mendi Raftari11Department of Geotechnics & Transportation, Faculty of Civil Engineering, Universiti TeknologiMalaysia, Johor, Malaysia2Department of Civil Engineering, Payame Noor University, Tehran, Iran

GRAPHICAL ABSTRACT

The effect of CaO, Na2SiO3, Al(OH)3, Al2(SO4)3, and CaCl2 on the surface charge and thediffuse double layer (DDL) thickness of a natural tropical peat were investigated in this study.Consequently, the flocculation and coagulation behavior of peat colloids were studied. As result,the thickness of DDL were changed significantly due to the addition of each electrolytes.The compression of the DDL thickness causes a weaker electrostatic repulsion and thereforea higher settlement rate. The surface charge of pure peat was almost zero at pH 3.2. The pHat the isoelectric point was increased by increasing the electrolyte concentration. The resultedflocculation and coagulation behavior of suspended peat in cationic reagents was in contrary withthe surface electrical charge characteristics where the Na2SiO3 and the Al2(SO4)3 electrolytesshowed the lowest and highest settlement rate, respectively.

Received 11 September 2012; accepted 12 September 2012.Address correspondence to Hossein Moayedi, Department of Geotechnics & Transportation, Faculty of Civil Engineering,

Universiti Teknologi Malaysia, Johor, Malaysia. E-mail: hossein.moayedi@gmail.com

Journal of Dispersion Science and Technology, 34:1273–1279, 2013

Copyright # Taylor & Francis Group, LLC

ISSN: 0193-2691 print=1532-2351 online

DOI: 10.1080/01932691.2012.738113

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Keywords Diffuse double layer, iso-electric point, natural peat, settlement rate, surfacecharge, zeta potential

1. INTRODUCTION

The surface of colloidal particles carries electriccharges, and these surface electrical charges are the basiccause for soil particles to possess a series of surface proper-ties. Soil surface charges affect the chemical properties ofthe soil through varying the quantity of electric chargeand the surface charge density. For instance, adsorptionsof anions and cations are caused by positive and negativesurface charges of the soil, respectively. The amount of ionsadsorbed is determined by the quantity of surface electriccharge, whereas the tightness of adsorption is related tocharge density. Besides, the formation of organo-mineralcomplexes, the migration of ions in soil, and the floccu-lation, dispersion, swelling, and shrinkage are all affectedby surface electric charge properties of the soil. Surfaceelectric charge in turn is a function of pH and dissolvedcationic salts concentration which normally measure bythe zeta (f) potential.[1,2]

The f potential is known as an intrinsic property ofcolloidal particles suspended in a liquid. Adsorption of ionsor dipolar molecules is determined by this charge andpotential distribution.[3–5] The electrical potential distri-bution itself determines the interaction energy betweenthe colloidal particles, and this is many cases responsiblefor the stability of particles toward coagulation and formany aspects of the flow behavior of the colloidal suspen-sion.[6,7] The f potential also determines the strength of therepulsive forces between soil colloidal particles and con-trols the stability of a colloidal system.[8,9] The colloidalinteraction of particles, including attraction and repulsion,changes with their inherent surface characteristics and theinterfacial layer composition around them, resulting inphysical and chemical equilibria between solid and aqueousphases.[10] The order of magnitude of the f potential givesan indication of the colloidal system stability.[4,5,11] If allthe particles in a suspension have high positive or negativef potentials, then they will not tend to attract each other(e.g., the colloids will tend to repel), with no tendency ofparticles to come together.[12,13] However, if the particlesshow a low f potential, there is no force to prevent themfrom coming together and flocculating. The dividing linebetween stable and unstable suspensions is usually takento be either þ30mV or �30mV. Particles with f potentialseither more positive than þ30mV or more negative than�30mV are considered stable. Driving forces in colloidalstability are the repulsive ones. It is therefore not surprisingthat when chemical species adsorbed on peat surfaces, itcan generate significant pH-dependent alterations in thesurface electrical charge and potential of the particles andtheir stability and flocculation: coagulation properties.

There are two basic mechanisms affecting dispersionstability-steric repulsion and electrostatic stabilization.Electrostatic or charge stabilization is the feature of par-ticle interaction that is due to the distribution of chargedspecies in the system.[12,14]

The main objective of current research is to assess theimpact of different monovalent and multivalent cationicreagents namely; sodium silicate (Na2SiO3), calcium oxide(CaO), calcium chloride (CaCl2), aluminum hydroxide(Al(OH)3), and aluminum sulfate (Al2(SO4)3) and atvaroius concentration on the surface electrical chargeproperties of the peat colloids. The influences of thesecationic reagents on the surface charge, absorption,dispersion and flocculation behavoiural of suspended peatare also evaluated.

2. MATERIAL AND METHODS

2.1. Material

Peat samples were collected and sealed to maintainsoil moisture in accordance with the British StandardInstitution (BS) methods of test for soils (BS 1377-1:1990) from several locations of Kg. Jawa Klang, Selangor,Malaysia. The physicochemical properties of the used peatin this study are presented in Table 1. The energy dispersivex-ray spectrometer (EDX) result of natural peat showedthe presence of oxygen (46.17%), carbon (29.28%), calcium(3.01%), alumina (2.48%), and silica (5.09%), accordingly.All of the chemicals were obtained from Merck Sdn.Bhd., Malaysia.

TABLE 1Physicochemical properties of peat samples

Parameters Unit Standard Values

Moisturecontent

% BS 1377-2-3 (1990) 159

Bulk density kN=m3 BS 1377-2-7 (1990) 9.73Specific gravity BS 1377-2-8.4

(1990)1.34

Organic content % BS 1377-3-4 (1990) 77Fiber content % ASTM-1997-91 39CEC meq 100 g�1 Gillman and

Sumpter (1986)54

pH ASTM - 4972 5.63Zeta (f)potential

mV ASTM - 4187 �17

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2.2. Experimental Methods

The f potential experiments were conducted at 25�C at0.1 g=L (solid-to-liquid ratios) of suspended particles. Thef potential of freshly prepared suspensions was determinedusing laser Doppler electrophoresis, namely, MalvernZetasizer IIc instrument made by Worcestershire, UK. Inbrief, each sample was placed in an electrophoresis celland then electric field was activated. This field caused theparticles to move with a velocity that was proportional totheir f potential, and the direction indicated whether theircharge was negative or positive.[15–17] All measurementswere made in 0.001, 0.01, 0.1, and 1.0mol=L concen-tration for electrolytes, namely, CaCl2, Na2SiO3, Al(OH)3,Al2(SO4)3, and CaO. pH adjustments also were made usingdilute 0.001M, HCl or NaOH solutions. All chemicalswere obtained from Merck Sdn. Bhd., Malaysia.

A series of the special flocculation experiments wereperformed to assess the effect of multivalent cationicreagents on the settlement rate. The results were presentedbased on the height of settlement within the 120 hours afterfinishing the stirring process. For the settlement ratemeasurements, a 20 g peat sample was transferred intoaqueous solution and the soil particles mixed homo-genously with a magnetic stirrer.

3. RESULTS AND DISCUSSIONS

3.1. Surface Electrical Charge Properties of Peat

The peat particles immersed in distilled water presenteda net negative charge. This is due the negative charges onthe both organic content and the layer silicates of themineral portion (e.g., kaolinite). In addition, the charge(f potential) was affected by pH. As the pH went up, thenet negative electric charge was produced. As the pHdropped, there was less and less negative charge(Figure 1). The f potential of peat colloids suspendedin the distilled water varied from þ8.25mV at pH 2.85 to

�31.35mV at pH 11.3. It was almost zero at pH 3.2. Thenatural pH of peat suspension was 5.93 with f potentialof �17mV (Figure 1).

The f potential of peat particles suspended in differentcationic reagents is presented in Figure 2. It was conductedbased on the natural suspension’s pH. Apparently, theresults show that the electrolyte type and concentrationshave a significant effect on the f potential values. Thecolloidal charge reversal occurred in peat colloids that wereimmersed in the 0.1mol=L of multivalent cationic reagents(Figure 2). It can be concluded that the peat colloids arehighly influenced by the electrolyte type and concentra-tions. By reducing the net charge of peat (e.g., compressingthe diffuse double layer (DDL)), cation binding leads to thereduction of repulsive interactions, again leading to soilcompaction. The more flocculated particles and the morecompacted soil lead to the higher shear strength as wellas the higher net flowability in the porous medial.[18]

3.2. Variation of the Zeta Potential Versus pH ofElectrolyte

Based on the electrophoresis theory, when an electric fieldis applied to soil colloidal particle that is suspended ina liquid, it moves toward the oppositely charged electrode[19].The electrical potential at the surface of colloids can be fixedor varied; the value of f potential changes with expansion orcompression of the diffuse layer, with adsorption of differentchemical reagents at the surface either nonuniformly oruniformly, thereby, changing the composition of the diffuselayer and hence the net charge of the kinetic particle. Theobserved result from the surface charge of peat colloidsimmersed in the different cationic reagent can clearly provethat the magnitude and sign of the peat’s f potentialis dependent on the interfacial chemistry of both liquid andsolid phase[14] (Figures 3–5).

The electrical surface charge of peat suspended in theNa2SiO3 was negative for the entire selected ion

FIG. 1. The variation of f potential of peat suspended in water versus Ph.FIG. 2. f potential of peat particles suspended in different electrolyte

concentrations. (Figure available in color online.)

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concentration. This is due to the presence silicate mineralsthat contains valence of �2 which in turn keep the surfacecharge of peat colloids negatively in difference reagent con-centrations. On the other hand, the hydration of Na2SiO3

causes the wall of the silica microchannel to be negativelycharged at most pH conditions, an accumulation of

positive ions (counter ions) occurs in the aqueous solutionadjacent to the silica wall[20,21] (Figure 3).

Figure 4 shows the variation of f potentials versus pHfor CaO, and CaCl2. As can be seen the suspended particlesin high molarities of the CaO and CaCl2 solution causedsurface charge reversal. However in low ion concentrationthe electrical charges were almost at iso¼ electric point(IEP). The f potentials of peat suspended in the 1mol=Lconcentration of CaO electrolyte were 15.06, 5.09, and11.3mV, at pH of 7.12, 9.89, and 13.1, respectively(Figure 4a). The DDL thickness of treated peat decreasedwhen only low molarities of CaCl2 used as electrolytesolution. The f potential of organomineral colloidssuspended in the 0.1 CaCl2 electrolyte was as low as 3 to�2mV. However when high molarities of CaCl2 used(e.g., 1.0mol=L CaCl2) the surface charge completelyreversed and DDL also increased significantly (Figure 4b).

The pH of both CaO and Na2SiO3 were found to beextremely alkaline. The pH of CaO was higher than 12even within the very low concentration range. However,the rest of electrolytes showed a lower pH (Figure 6).The variations in f potential with pH were probably relatedto the nature of electrical energy field in peats. The humusis dynamic and very active as regards electric charge. The

FIG. 5. Zeta potential versus pH of the suspended peat in the trivalent

cation: (a) Al(OH)3; (b) Al2(SO4)3..

FIG. 4. Zeta potential versus pH of the suspended peat in (a) CaO and

(b) CaCl2.

FIG. 3. Zeta potential versus pH of the suspended peat in the mono-

valent cation, Na2SiO3.

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source of electro negativity (i.e., CEC) and source of ionsare chemical properties, and the consistency and the largesurface area per unit of mass were physical propertiesimparted to the peat by humus, respectively.[22]

As pH of pure fluid increases, the f potential becomesmore negative. However, in a very alkaline environment(pH� 11), we cannot see such behavior, because near thispH the divalent cation, Ca2þ, precipitates as the hydroxidefrom the bulk solution, as Equation (1):

C2þa þ 2OH ! CaðOHÞ2 + ½1�

where the symbol + indicates precipitation. The precipi-tation of Ca(OH)2 does not allow accurate measurementof the f potential of soils. Furthermore, there are variationsin the magnitude of the f potential of minerals withdivalent cations.[23] This phenomenon arises because ofvariations in the hydrated ionic radius of cations: the largerthe ionic radius, the less negative is the f potential. This isbecause a highly hydrated ionic radius causes a larger Sternlayer, which results in a thicker DDL.[23] The lack ofcurrent information for the surface charge of the colloidalparticles suspended in chemical species (e.g., calciumchloride, and calcium oxide) upon pH� 11 can only befind by interpreting the EOF results that observed fromthe EK injection of that reagents.

3.3. Effect of Electrolyte Type and Concentrationon the IEP

At a certain pH, the soil surface charge could drop tozero, rendering a zero f potential or what is called theIEP.[24] The concept of IEP is important in electrical poten-tial measurements and is mostly used to describe the effectof changing DDL thickness (e.g., changes in measured fpotential), ions present, and electrical conductivity ofsoils.[6,25–27] Reliable values of pH at IEP for various mate-rials are much desired in colloid chemistry, in materialsscience, soil science, geochemistry, catalysis, and wastewater management.[28] It is noteworthy conditions thatfavor dispersion of colloids are a high state of hydration,

a low electrolyte content, a pH far from the IEP andabsence of oppositely charged colloids in the same system.On the other hand, conditions that favor flocculation are ahigh electrolyte content, dehydration, a pH at IEP, and thepresence of an oppositely changed colloid.[26] As shown inFigures 3–5 the surface charge of the negatively peat parti-cles suspended in the high concentrations of the diavalent(e.g., CaO, CaCl2), and=or the trivalent cationic reagents(e.g., Al(OH)3, and Al2(SO4)3) changed to the positive.

As it mentioned earlier, the main inorganic fraction ofthe soil sample in this study was kaolin. The major compo-nents of kaolin are aluminosilicate minerals composed ofaluminum, silicon, and oxygen, plus countercations.[29] Itis indeed well established that on the surface of aluminosi-licates, there are Al-OH groups as well as Si-OH groups.The Si-OH groups can release protons, so they will producenegative surface charges. By the way, Al-OH groupscan also accept protons or release OH� ions, causing thesurface to carry positive charges.[30]

The peat surface charge was dropped to zero at pH 3.2.The IEP for multivalent cationic reagent in their naturalpH was observed between 0.01mol=L and 0.1mol=Lelectrolyte concentrations. The higher electrolyte concen-tration posses a higher pH values for the IEP (Figure 7).However the surface charge of the peat in both acidicand alkaline medium is reveresed by adding 1mol=L ofCaCl2, and CaO electrolytes. According to the variationof f potential versus pH for both CaCl2, and CaO electro-lytes (presented in the Figure 4) it can be concluded thatthe IEP will not happened in the high molarities of thesetwo electrolytes. Consequently, there was no recordedIEP for the mentioned boundary conditions (Figure 7).In contrast with multivalent reagents, the surface chargeof the colloidal particles suspended in the Na2SiO3 (e.g.,as a monovalent cation) solution showed a negligibledecompression in the DDL thickness and the IEP did notdevelop in this solution too. The negative surface charge

FIG. 7. Effect of electrolyte types and concentrations in the suspen-

sion’s pH at the IEP. (Figure available in color online.)

FIG. 6. pH versus electrolyte concentration of the suspension.

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of the organic colloidal particles immersed in the Na2SiO3

suspension is discussed earlier.

3.4. Absorption Behavior of Peat throughCationic Solutions

As it stated earlier, cation binding in the peat hasconsequences for the behavior of the organic compoundsthemselves, influencing adsorption, solubility, flocculation,and aggregation and thereby soil structure, translocation oforganic content within soils, and transport to waters.[18,22]

Other processes involving soil organic matter, for instancemetabolic transformations, water holding, weathering andinteractions with enzymes, are also affected by cationbinding.[18,31,32] Besides, organic content adsorb to thesurfaces of mineral particles, clays and oxides. The extentof interaction depends strongly upon the concentrationsand nature of the cations that are present.[18] As stated,when the net charge is zero (or IEP), peat colloidal particleswill not repel each other but will tend to aggregate andform larger particles.[33] In contrast, negatively and=orpositively charged soil particles repel each other, resultingin dispersion and less settlement.[15,23,34]

A series of especial flocculation experiment weredesigned to evaluate the settlement potential of the peatcolloids after immersing thorough the different cationicreagents. Each sample was stirred for 10 minutes usingmagnetic stirrer and left for 120 hours in order to checktheir flocculation and coagulation potential. Although suchtest is not supported by any specified standard, it givesa schematic view of how multivalent cationic stabilizersable to flocculate and=or dispersed the suspended organicparticles. The schematic view of settlement rate for peatsuspended in the CaCl2 solution is presented in Figure 8.The low molarities of Ca2þ ions (e.g., up to 0.01mol=LCaCl2) causes a remarkable flocculation (due to the linkagebetween the cations and negatively peat colloids) of thesuspended peat colloids and consequently results a higherrate of coagulation and settled particles (Figure 9).

As showed in Figure 2, the net charge of the treated soilis reversed by addition of high concentration of the cations

(e.g., Ca2þ and Al3þ) from negative to the positive. Meansthat high concentrations of the multivalent cationicreagents cause the peat colloidal particles to repel eachother and prevent them from aggregating. It means,due to the addition of extra calcium cations, the chargebalances in the confection, giving a positive charge to thepeat and thereby resulting of deflocculating of the large sizeparticles. Figure 10 showed the effect of cationic reagentconcentrations on the settlement rate of peat colloids.As it stated earlier, the flocculation and dispersionbehavioral are influenced by the surface electrical chargeof the peat particles (e.g., DDL thickness). Apparently,the provided results in Figure 10 are in contrarywith the observed results for the surface charge charac-teristics of peat immersed in different cationic reagents(Figure 2).

The lowest settlement rate was belongs to the Na2SiO3

electrolyte where a negligible settlement was measure(Figure 9). The presence of SiO2 atoms with valence of�2 enhanced the negative charge of the peat. However, asmall rate of settlement can be seen clearly for the0.001mol=L Na2SiO3 solution. Such small settlement couldbe due to the presence of small cationic atoms that nat-urally available in the peat such as calcium (3.01%), andalumina (2.48%) atoms.

FIG. 9. Effect of cationic reagent concentrations on the settlement

rate of peat colloids. (Figure available in color online.)

FIG. 8. Settlement rate for peat samples suspended in the CaCl2solutions. (Figure available in color online.)

FIG. 10. Schematic view of suspended peat particles settled after

addition of the Na2SiO3 solutions. (Figure available in color online.)

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4. CONCLUSIONS

Several laboratory experiments, namely, f potential,pH, flocculation, and coagulation were conducted to assessthe impact of monovalent and multivalent cationicreagents on the surface electrical charge charactristics ofthe peat. Generally, presences of electrolytes are reducedrepulsive electrostatic interactions and thus allow colloidsto aggregate and form clusters. These clusters (or flocks)settle down quicker because their size is larger and gravityforces are dominating over diffusion. Thus, the sizedistribution of the colloids plays an important role in thisstudy. The following conclusions are drawn based on thisstudy:

. The f potential of peat colloids suspended in thedistilled water varied from þ8.25mV at pH 2.85to �31.35mV at pH 11.3. The peat surface chargewas dropped to zero at pH 3.2. The variations inf potential with pH were related to the nature ofelectrical energy field in peat.

. The IEP for multivalent cationic reagent intheir natural pH was observed between the0.01mol=L and 0.1mol=L electrolyte concentra-tions. The higher electrolyte concentration possesa higher pH values for the IEP. There was noIEP observed for the Na2SiO3 reagent due to itsconstant negative charge within the pH variation.

. The used electrolyte type and concentration hasan important effect on the surface charge of thepeat particles as well as their settlement rate.Suspensions with the high molarities of CaCl2and Al(OH)3, and CaO caused colloidal chargereversal in the surface of the colloidal from thenegative to the positive.

. The Na2SiO3 and the Al2(SO4)3 electrolytesshowed the lowest and highest settlementrate, respectively. The resulted flocculation andcoagulation behavior of peat was contrary toand dominated from its surface electrical chargecharacteristics.

REFERENCES

[1] Brunelle, M.T. (1980) Desalination, 32: 127–135.[2] Niriella, D. and Carnahan, R.P. (2006) Journal of Dispersion

Science and Technology, 27 (1): 123–131.[3] Hlavacek, M. and Remy, J.F. (1995) Separation Science and

Technology, 30 (4): 549–563.[4] Sabah, E., Mart, U., Cınar, M., and Celik, M.S. (2007)

Separation Science and Technology, 42 (10): 2275–2288.

[5] Moayedi, H., Huat, B.B.K., Kazemian, S., and Mohammad,T.A. (2012) Journal of Dispersion Science and Technology, 33(1): 103–110.

[6] Carlson, J.J. and Kawatra, S.K. (2011) Mineral Processingand Extractive Metallurgy Review, 34: 269–303.

[7] Gallardo, M.A.M., Calzado, M.R., Gonzalez, M.M.L.,and Perez, G.C. (2006) Journal of Dispersion Science andTechnology, 27 (1): 23–32.

[8] Hunter, R.J. (1993) Introduction to Modern Colloid Science;New York: Oxford University Press.

[9] Gu, Y.Y., Yeung, A.T., Koenig, A., and Li, H.J. (2009)Separation Science and Technology, 44 (10): 2203–2222.

[10] Majzik, A. and Tombacz, E. (2007) Organic Geochemistry,38 (8): 1330–1340.

[11] Yu, T.R. (1997) Chemistry of Variable Charge Soils; London:Oxford University Press.

[12] Segota, S., Heimer, S., and Tezak, D. (2006) Colloidsand Surfaces A: Physicochemical and Engineering Aspects,274 (1–3): 91–99.

[13] Chen, W.J. (1998) Separation Science and Technology, 33 (4):569–590.

[14] Moayedi, H., Huat, B.B.K., Kazemian, S., Behpour, M., andNiroumand, H. (2012) Journal of Dispersion Science andTechnology, In press.

[15] West, L.J. and Stewart, D.I. (1995) Geotechnical SpecialPublication, 1535–1549.

[16] Czapla, C., Bart, H.J., and Jesberger, M. (2000) SeparationScience and Technology, 35 (9): 1423–1438.

[17] Foss, M., Gulbrandsen, E., and Sjoblom, J. (2010) Journal ofDispersion Science and Technology, 31 (2): 233–240.

[18] Tipping, E. (2002) Cation Binding by Humic Substances;Cambridge, UK: Cambridge University Press.

[19] Deyl, Z. (1984) Separation Methods; New York: ElsevierScience.

[20] Fu, L.M., Lin, J.Y., and Yang, R.J. (2003) Journal of ColloidAnd Interface Science, 258 (2): 266–275.

[21] Ruijin, W., Jianzhong, L., and Zhihua, L. (2005) BiomedicalMicrodevices, 7 (2): 131–135.

[22] Stevenson, F.J. (1994) Humus Chemistry: Genesis, Composition,Reactions; New York: Wiley.

[23] Kaya, A. and Yukselen, Y. (2005) Canadian GeotechnicalJournal, 42 (5): 1280–1289.

[24] Lorenz, P.B. (1969) Clays and Clay Minerals, 17: 223–231.[25] Hunter, R.J. (1981) Zeta Potential in Colloid Science; New

York: Academic Press.

[26] Bear, F.E. (1964) Chemistry of the Soil; New York: Reinhold.[27] Kaya, A. and Fang, H.Y. (1996) Characterization of

Dielectric Constant on Fine-GrainedSoil Behavior; ASTM

Special Technical Publication.[28] Kosmulski, M. (2012) Advances in Colloid and Interface

Science, 171–172: 77–86[29] Sparks, D.L. (1986) Soil Physical Chemistry; London:

CRC Press.[30] Krnel, K. and Kosmac, T. (2000) Journal of the American

Ceramic Society, 83 (6): 1375–1378.

[31] Abdullah, W.S. and Al-Abadi, A.M. (2010) Applied ClayScience, 47 (3–4): 343–350.

[32] Mitchell, J.K. and Soga, K. (2005) Fundamentals ofSoil Behavior; New York: John Wiley and Sons.

[33] Yukselen, Y. and Kaya, A. (2003) Water, Air, and SoilPollution, 145 (4): 155–168.

[34] Shang, J.Q. (1997) Canadian Geotechnical Journal, 34 (4):627–631.

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