preparation,characterization,andapplicationof metakaolin ......biochar microparticles [24], silica...

Research ArticlePreparation Characterization and Application ofMetakaolin-Based Geopolymer for Removal of MethyleneBlue from Aqueous Solution

Marouane El Alouani Saliha Alehyen Mohammed El Achouri and Mrsquohamed Taibi

Mohammed V University in Rabat Laboratoire de Physico-chimie des Materiaux Inorganiques et Organiques (LPCMIO)Ecole Normale Superieure (ENS) Centre des Sciences des Materiaux (CSM) Rabat Morocco

Correspondence should be addressed to Marouane El Alouani maelalouanigmailcom

Received 30 January 2019 Revised 5 April 2019 Accepted 14 April 2019 Published 28 May 2019

Guest Editor Mohamed Zbair

Copyright copy 2019 Marouane El Alouani et al (is is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Metakaolin-based geopolymers are aluminosilicate materials that can be used as cationic dye adsorbents in aqueous systemtreatment Our aim in this paper is to study the ability of geopolymer powder produced frommetakaolin and alkaline activators toact as an adsorbent to removemethylene blue (MB)(e solid materials were systematically analyzed by X-ray fluorescence (XRF)X-ray diffraction (XRD) Fourier-transform infrared spectrometery (FTIR) scanning electron microscopy (SEM) energy dis-persive X-ray analysis (EDX) and the point of zero charge XRF FTIR XRD SEM and EDX analyses confirmed the formation ofa geopolymer composite by geopolymerization reaction(e influence of various experimental factors such as geopolymer dosagepH initial dye concentration contact time and temperature was assessed Adsorption isotherms were evaluated by LangmuirFreundlich Temkin and DubininndashRadushkevich isotherms Kinetics data were studied using pseudo-first-order pseudo-second-order and intraparticle diffusion models (e thermodynamic parameters namely Gibbs free energy (ΔGdeg) enthalpy (ΔHdeg) andentropy (ΔSdeg) were determined (e results indicated that the maximum decolorization was found in high pH values (ecollected isotherm data were best fitted by the Langmuir isotherm and the maximum adsorption capacity of dye onto thegeopolymer was 4348mgg (e experiment kinetics followed the pseudo-second-order kinetic models (e thermodynamicresults demonstrated that the adsorption of the obtained material occurs spontaneously as an endothermic process (e resultsconfirmed that the prepared adsorbent can be used for remediation of water contaminated by MB dye

1 Introduction

(e rapid industrial growth has led to the release of differentdyes in the aquatic environment and the treatment of effluentshas become a challenging topic in environmental sciencesWith the wide applications of dyes in multiple fields such astextile leather additives petroleum product paper cottonwool plastic and pharmaceutical industries water pollutioncaused by the colorants is increased which has attracted theattention of the scientific community [1 2] Generally syn-thetic nondegradable dyes not only pollute water resources butalso affect the human health because of their toxic nature [3]In addition their presence in aquatic systems even at lowconcentrations reduces the penetration of light and thereforehas a detrimental effect on photosynthesis [4] Consequently

the presence of trace amounts of these micropollutants(lt1 ppm) in industrial wastewater is extremely noticeable andunwanted [5] Among the most used industrial dyes meth-ylene blue (MB) is a basic dyestuff widely used in variousindustries such as textile dyeing petroleum industries andcolor photography (erefore the treatment of water con-taminated by these chemicals is necessary both for the pro-tection of the environment and for the reuse of theseunconventional waters In recent years different techniqueshave been developed and tested to recover toxic substancesfrom wastewaters before discharging into an aquatic envi-ronment such as coagulation [6] advanced oxidation [7]photocatalytic degradation [8] ultrafiltration [9] ion-exchange [10] electrochemical treatment [11] and adsorp-tion [12ndash15] Among various physicochemical processes

HindawiJournal of ChemistryVolume 2019 Article ID 4212901 14 pageshttpsdoiorg10115520194212901

adsorption is a technique of choice due to its low cost simpledesign and reusability [16 17] Different categories of naturaland synthetic adsorbents were utilized for the removal of thisorganic material from aquatic media such as kaolin [18]zeolite [19] activated carbon [20] mesoporous birnessite [1]natural clay [21] magnetic chitosan [22] fruit peels [23]biochar microparticles [24] silica [25] loofah sponge-basedporous carbons [26] pyrophyllite [24] and Fe3O4activatedmontmorillonite nanocomposite [27] Among the synthesizedadsorbents mostly used to remove organic matters are geo-polymers [28] Geopolymers firstly named by Joseph Davi-dovits [29] are formed by activation of aluminosilicateprecursors and these solids can be natural (kaolin micaandalusite spinelle illite or Slag Hill) or synthetic (meta-kaolin fly ash calcined by-products or industrial residues)activated by alkali silicate solution (typically Na or K) attemperatures between 20degC and 100degC [30] Corresponding todifferent SiAl ratios the materials are composed of networkstructures of (Na K)-poly(sialate) (-O-Si-O-Al-O-)n (Na K)-poly(sialat-siloxo) (-O-Si-O-Al-O-Si-O)n and (Na K)-poly(sialate-disiloxo) (O-Si-O-Al-O-Si-O-Si-O-)n [29] (egeopolymers or inorganic polymers have also gained signifi-cant attention as efficient adsorbents with good physical andchemical properties Recently several studies were conductedin the interest of activation of aluminosilicate precursorscharacterized and tested for removal of dyestuffs and haz-ardous materials from aquatic environment [8 31 32]

In this work a geopolymerization method was applied tosynthesize the metakaolin-based geopolymer (e structuraland morphological properties of the elaborated adsorbentwere characterized by XRF XRD FTIR and SEM analyses(e adsorption properties of the elaborated sample werestudied in different experimental conditions includingadsorbent mass pH contact time initial dye solution andtemperature (e adsorption kinetics isotherms and ther-modynamics data of the adsorption were investigated tostudy the batch adsorption process of the basic dye using thesynthesized metakaolin-based geopolymer

2 Materials and Experimental Methods

21Materials andChemicals Kaolin was collected from BabMssila situated at Ribat El Kheir next to Sefrou city in thenorthwest of Morocco (e raw clay was subjected to cal-cination at temperatures of 800degC for 3 h

(e industrial-grade sodium silicate powder (Honey-well Riedel-de Haen Germany 18 wt Na2O 63 wtSiO2 18 wt loss on ignition) and commercial sodiumhydroxide (NaOH 99 purity) (ACS AR-grade pellets)were provided by Sigma-Aldrich Methylene blue (MB) dyewith the chemical composition C16H18ClN3S and a MW of319852 gmol was supplied by Sigma-Aldrich

22 Geopolymer Synthesis (e geopolymer sample wassynthesized in several steps (e first step was to synthesizethe activator solution by initially dissolving Na2SiO3 powderand sodium hydroxide NaOH (12M) at a mass ratio of 25[33] (e mixture was stirred at room temperature for a

period of 15min (e second step of the elaboration is themixing of metakaolin with the activator solution which wasconducted using in a mixer with constant stirring at ambienttemperature for 15min to obtain good homogenization(en distilled water was added at a ratio watermetakaolinof 034 to obtain the desired workability of the geopolymerpaste (e mixture was placed in a cylindrical mould andtreated at 60degC for 24 hours Finally the matrix was sieved toparticle sizes lt200 μm and stored in a desiccator for char-acterization and investigation of the adsorption tests (emix proportions of the metakaolin-based geopolymer pastesare displayed in Table 1

23 Adsorption Experiments A series of batch adsorptionexperiments were carried out under different operatingconditions related to adsorbent mass (005ndash035 g) contacttime (0ndash220min) initial solution pH (2ndash13) initial dyeconcentration (5ndash60mgL) and temperature (20ndash70degC) at aconstant agitation speed (250 rpm) (Table 2) (e solutionpH was adjusted to optimum values using 01M NaOH or01M HCl Afterwards the sample was centrifuged at2500 rpm for 10min (e initial and the residual concen-trations of MB were measured using a spectrophotometer ata wavelength of 664 nm (e removal efficiency of themetakaolin-based geopolymer was calculated using equation(1) adsorption capacity at any time qt (mgmiddotgminus1) was obtainedusing equation (2) and adsorption capacity at equilibrium qe(mgmiddotgminus1) was determined using equation (3)

removal Ci minusCt( 1113857

Ci

times 100 (1)

qt Ci minusCt( 1113857

mV (2)

qe Ci minusCe( 1113857

mV (3)

where Ci (mgmiddotLminus1) is the initial concentration of MB solu-tion Ce (mgmiddotLminus1) and Ct (mgmiddotLminus1) are respectively theliquid-phase concentration of MB at initial time and at anytime t after the adsorption process m (g) is the weight ofgeopolymer and V (L) is the volume of the MB solution

24 Instrument Analysis (e chemical compositions ofmaterials and the prepared adsorbent were determined byX-ray fluorescence using a spectrometer dispersionwavelength-type Axios (e crystalline phases of the samplewere detected using an X-ray diffractometer (Philips model1840 equipment) (e functional groups of samples weredetected using Fourier-transform infrared spectrometrybruker platinum ATR apparatus in the range of 4000ndash400 cmminus1 wavelengths (e microstructure of metakaolinand metakaolin-based geopolymer was observed using theJEOL-6300F field-scanning electron microscope (SEMEDX) (e concentration of MB was determined usingthe spectrophotometer JASCO V-630 UVVIS A pH-metermodel (M 210) was used for pH measurement

2 Journal of Chemistry

(e pH at the point of zero charge (pHpzc) of thegeopolymer was determined by the method described byPawar et al [34] A series of (001M) KNO3 solution(V 100mL) were prepared and the initial pH of KNO3 wasadjusted to a given value from pH 2 to 13 by the addition ofHCl (01M) or NaOH (01M) To each solution 01 g ofgeopolymer was added and shaken for 48 h with an agitationspeed of 120 rpm at room temperature (e differencesbetween the pH value of the initial solution (pHI) and thefinal solution (pHF) were plotted as a function of pHI (epoint of intersection of this curve yielded the point of zerocharge

3 Results and Discussion

31 Structural Analysis

311 Chemical Analysis of Solids (e chemical compositionof metakaolin and the synthesized sample is illustrated in

Table 3 (e XRF analysis indicates that the metakaolin isbasically formed by SiO2 Al2O3 and Na2O After activationof metakaolin by the alkali solution it was found that a newinorganic material with an SiAl ratio of approximately 204was formed indicating the poly(sialate-siloxo) (PSS) (-Si-O-Al-O-Si-O-)n nature of the formed material [35]

312 X-Ray Diffraction Figure 1 shows the XRD patterns ofkaolin metakaolin and geopolymer (e results of DRXanalysis for kaolin show that the material is rich in kaoliniteand quartz After calcination the disappearance of the peakscorresponding to kaolinite is observed which is explained bythe dehydroxylation of the water molecules that exist in thekaolinite structure in metakaolinite by heat treatment [36]After the activation process the crystalline phases weredissolved in the alkaline solution and the aluminosilicatephase was formed in the surface of metakaolin by geo-polymerization reaction [37] (ese results indicated the

Table 1 Chemical formulation of geopolymer

Mixture ofgeopolymer

Metakaolin(g)

NaOH(g)

Silicate(g)

Mass of water ofNaOH dilution (g)

Extrawater (g)

Totalwater(g)

Ratio watermetakaolin

Ratio metakaolinalkaline activator

RatioNa2SiO3NaOH

Massratio (g) 50 5715 14285 11905 5 16905 034 25 25

Table 2 Experimental conditions for the adsorption of MB on geopolymer

Investigated parameter Temperature (degC) pH Geopolymer dosage (g) Contact time (min) Initial concentration (mgL)

Geopolymer dosage (g) 25 5

005

120 40

010150202503035

Contact time (min) 25 5 01

0

20 30 40

306090120150180220

pH 25

221

01 120 40

44661680910061206

Temperature (degC)20

5 01 120 405070

Initial concentration (mgL) 25 5 01 120

510204060

Journal of Chemistry 3

formation of a new product with a structure different fromthat of metakaolin

313 Infrared Spectroscopy (e FTIR spectra of kaolinmetakaolin and elaborated matrix are depicted in Fig-ure 2 and all the band assignments are presented inTable 4 In kaolin the bands at 3350 and 1622 cmminus1correspond to OH stretching and deformation of thehydroxyl group respectively (e adsorption bandappearing at 1436 cmminus1 is related to the stretching vi-brations of O-C-O due to atmospheric carbonation on thesurface of kaolin (e band at 1151 cmminus1 is due to the Si-Ooutside of the plane-stretching vibration (e most in-tensive band at 998 was due to Si-O-Al stretching vi-bration Bands which exist between 757 cmndash1 and532 cmndash1 correspond to stretching vibrations of Si-O-Al(e band at 437 cmminus1 is related to the Si-O-Si bendingvibration After calcination no bands were observedbetween 3350 and 1622 cmminus1 in metakaolin suggestingthat the thermal treatment was adequate to convert kaolinto metakaolin (e asymmetric stretching vibration of Si-O-T (T Al or Si) at 988 cmminus1 in metakaolin shifted

approximately 9 cmminus1 after the geopolymerization re-action to 979 cmminus1 (e shifting and reduction of peaks inFTIR spectrum confirms the formation of a thepoly(sialate-siloxo) chain in the structure by geo-polymerization reaction [47]

314 Microstructural Analysis (SEMEDX) Figure 3 showsthe representative SEM images of metakaolin and thesynthesized matrix (e surface morphology of meta-kaolin was different from that of the geopolymer matrixSEM images (Figure 3(a)) of metakaolin showed that thesample is a heterogeneous material consisting of irregu-larly shaped particles After the geopolymerization re-action (Figure 3(b)) the morphology of the geopolymer isconstituted by a chain of polysilicate layers by the com-plete disappearance of metakaolin particles (is mor-phological change observed in the synthesizedgeopolymer is due to the dissolution of metakaolin alu-minosilicates in the activator solution leading to theformation of aluminosilicate gel EDX microanalysis wasused to characterize the elemental composition of themetakaolin and geopolymer (Figure 3) According to the

Table 3 Quantitative chemical composition of metakaolin and geopolymer

Oxides (wt) Metakaolin Geopolymer Elements (wt) Metakaolin GeopolymerSiO2 376 31 O 467 456Al2O3 196 134 Na 11 204Na2O 149 275 Si 176 145MgO 846 594 Al 104 708CaO 235 166 Fe 192 129Fe2O3 275 185 K 132 0936K2O 15 113 Ca 168 119SO3 414 34 S 166 136Loss on ignition 774 135 Mg 54 358SiO3Al2O3 192 231 SiAl 17 204

10 20 30 40 50

QQK

K

Q

Q

Q

2θ (deg)

KaolinMetakaolinGeopolymer

Q

KKK

Q

K

K

Figure 1 XRD patterns of kaolin metakaolin and geopolymer

4000 3500 3000 2500 2000 1500 1000 500

446

556

446

1111

979

988

1622

437

532

593

757

662

988

1151

1436

6153410

Tran

smitt

ance

()

Wavenumber (cmndash1)


3550

Figure 2 FTIR spectrum of kaolin metakaolin and geopolymer


EDX analysis (Figure 3(a)) the major elements wereoxygen silicon and aluminum with proportion values of4987 2077 and 1488 respectively (e percentage ofsodium elements increased from 061 to 1417(Figure 3(b)) this is due to the alkali activator used in thegeopolymerization process

32 Batch Adsorption Test

321 Effect of Adsorbent Dose (e effect of adsorbent doseon the removal of MB was investigated and the results areshown in Figure 4 As can be seen when the geopolymermass increased from 005 to 035 gL the MB removal

Table 4 FTIR bands (cmminus1) of kaolin metakaolin and geopolymer

Bands (cmminus1)Assignments References

Kaolin Metakaolin Geopolymer3550 mdash mdash Stretching and deformation of OH [38]3410 mdash mdash Stretching and deformation of OH [34]1622 mdash mdash Stretching and deformation of OH [34]1436 mdash mdash Stretching vibration of O-C-O [39]1151 mdash 1111 Si-O-Si bending vibration [40]988 988 979 Stretching vibration of Si-O-T (TAl or si) [41]757 757 mdash Bending vibration of Si-O-Al [42]662 662 664 Bending vibration of Si-O-Al [43]593 593 mdash Bending vibration of Si-O-Al [44]532 553 553 Bending vibration of Si-O-Al [45]437 446 446 Bending vibration of Si-O-Si [46]

(cps

eV

)

45

40

35

30

25

20

15

105

01 2 3 4 5

Energy (keV)

Element Atomic Weight O 55694987Na 048061Al 9851488Si 13212077

6 7 8 9 10

E1 2960

(a)

(cps

eV

)

45

40

35

30

25

20

15

10

5

02 4 6 8

Energy (keV)10 12 14


E2 2968

(b)

Figure 3 SEM micrographs and energy dispersive X-ray analysis (EDX) of metakaolin (a) and geopolymer (b)


efficiency increased from 55 to 9977 (is result mightattribute to the increasing number of binding sites in thegeopolymer for MB removal by increasing the quantity ofadsorbents [48] A similar trend was obtained for this toxicdye removal on the geopolymer paste [49] and phosphoricacid-based geopolymers [50] Optimizing the mass of theadsorbent is a very important parameter for controlling theadsorption capacity According to the experimental resultsthe adsorption assays should be performed using 01 g100mL for MB

322 Effect of pH on the Removal Efficiency and pH Point ofZero Charge (pHpzc) of Geopolymer (e influence of pH isan important factor for removal of organic matter fromwater Figure 5(a) represents the effect of the solutionʼsinitial pH in the adsorption process It is observed that theremoval efficiency increases with the rise in the pH value andreaches 912 at a pH value of 1206 (e removal is affectedby the change in the pH value of the solution In acidicmedium the surface of the geopolymer is surrounded by H+

ions which decrease the interaction of the solute ions (MB+)with the sites of the geopolymeric material On the contraryin the basic medium the concentration of H+ ions decreasesand generates a good interaction between the dye ions andthe sites of the surface Similar adsorption behaviors of MBwere reported by several investigations [20 51] In order toconfirm this result it is necessary to determine the pHpzc ofthe adsorbent (e zero point of charge (PZC) is defined asthe number of positive charges equal to the number ofnegative charges that exist on the surface of the adsorbent(e pHPZC of the geopolymer is shown in Figure 5(b) andthe pHPZC value of the adsorbent was found almost to be 9(us at pHlt 9 the surface of the geopolymer is positivelycharged and becomes negatively charged at pHgt 9 (ere-fore with increasing pH above pHpzc 9 the removal ofcationic dye by the geopolymer increased slightly (e re-moval increase can be explained by electrostatic attractionbetween the particles of the geopolymer which is negativelycharged and the cationic dye which is positively charged[52] (ese results show that the attraction between the

inorganic framework (negatively charged) and the methy-lene blue (positively charged) depends on pH

323 Effect of Contact Time and Kinetics

(1) Effect of Contact Time (e effect of contact time on theremoval of MB by the geopolymer is shown in Figure 6 (eresults demonstrate that the removal percentage of MB israpid in the first 30min of contact time Afterwards theequilibrium time is reached within 180 180 and 150min for20 30 and 40mgL respectively After the equilibrium nosignificant change in the removal percentage of the geo-polymer was observed in the different dye concentration Itwas observed that for an increased contact time from 30 to240min the efficiency augmented from 8750 to 100 90 to99 and 8750 to 9790 for concentrations of 20 30 and40mgL respectively It can be seen that the decrease of MBremoval with increasing initial MB concentration is due tothe saturation of the adsorbent surface at high dye con-centrations Similar result was reported by Hamid et al [53]

(2) Kinetics Studies (ere are several mathematical modelsused to describe the adsorption kinetics of pollutants ontothe adsorbent material In this study three kinetic models

000 005 010 015 020 025 030 035 04040

60

80

100

re

mov

al

Mass (g)

Figure 4 Effect of adsorbent dose on the removal efficiency

2 4 6 8 10 1260

65

70

75

80

85

90

95

100

re

mov

al

pH

(a)

2 4 6 8 10 12 14

ndash5

ndash4

ndash3

ndash2

ndash1

0

1

2

pHI ndash

pH

F

pHIpHpzc = 9

(b)

Figure 5 Effect of pH on adsorption of MB onto geopolymer(a) and point of zero charge (pHpzc) of geopolymer (b)


(pseudo-first-order pseudo-second-order and intraparticlediffusion) were applied for the adsorption of MB by thegeopolymer to describe the adsorption process

(e pseudo-first-order model [54] is expressed asfollows

ln qe minus qt( 1113857 ln qe minus k1t (4)

(e pseudo-second-order model [55] is represented bythe following equation

t

qt

1k2q

2e

+t

qe (5)

(e intraparticle diffusion model [56] is given by thefollowing equation

qt kIt12

+ I (6)

where qe (mgg) is the adsorption capacity at equilibriumqt (mgg) is the adsorbed concentration of MB at time t k1(1min) is the pseudo-first-order rate constant for theadsorption process k2 (gmgmiddotmin) is the pseudo-second-order rate constant for the adsorption process kI (mg(gmiddotmin05)) is the intraparticle diffusion rate constant and I(mgg) is the intercept

(e fitting results are shown in Figures 7(a)ndash7(c) and thekinetics constants and correlation coefficients calculated forpseudo-first-order pseudo-second-order and intraparticle-diffusion equations are listed in Table 5 (ese resultsrevealed that the adsorption of MB on the geopolymermatrix is best described by the pseudo-second-order kineticmodel with a high correlation coefficient (0999) and thecalculated qe(cal) values are in agreement with experimentalqe(exp) values at different initial MB concentrations (eseresults indicate that the chemical interaction process in-volves electron sharing and exchange between MB andfunctional groups of the geopolymer [57] Similar resultswere also found in previous studies [23 58]

(e sialate geopolymer network consists of (SiO4) and(AlO4) groups connected by covalent bond Si-O-Al- (e(Na+) cations present in the structural cavities of the pol-y(sialate) balance the negative charge of Al3+ in coordination(IV) [29] During the adsorption phenomena the removal ofMB by the adsorbent can be explained by the interactionsbetween the positive charge of (MB+) and the negativecharge of Al tetrahedral (-Si-O-Alminus-O-Si-O) in themetakaolin-based geopolymer (Figure 8) (is proposedmechanism explains the chemisorption of methylene blue bythe metakaolin-based geopolymer

324 Effect of Initial Concentration Dye and Isotherms

(1) Effect of Initial Concentration Dye (e effect of varyingMB initial concentration on the adsorption capacity of MBby the geopolymer is shown in Figure 9 It can be seen thatthe adsorption capacity of MB increased as the initial MBconcentration increased Adsorption capacities of the geo-polymer increase with the initial MB concentration increasedue to the increase in the driving force of the concentrationgradient [59] A similar observation was reported previouslyfor MB removal on mesoporous birnessite [1] and Cu-BTC[58]

(2) Isotherm Studies To investigate the adsorptionmechanism of the distribution of adsorbatemolecules betweenthe liquid and the solid phase four different models (Lang-muir Freundlich Temkin and DubininndashRadushkevich) wereemployed to fit the adsorption data

33 Langmuir Isotherm Langmuir isotherm model is ap-plied to explain the adsorption mechanism onto a homo-geneous surface and calculate the monolayer adsorptioncapacity in the surface of the adsorbent [60] (is model isexpressed by the following

Ce

qe

1KLqm

+Ce

qm (7)

where qe is the amount of dye at equilibrium (mgg)Ce is theequilibrium concentration of the pollutant (mgL) qm is theamount of monolayer adsorption capacity (mgg) and KL isthe Langmuir constant (Lmg)

(e essential characteristic of the Langmuir isotherm canbe expressed by the dimensionless constant separation factorRL defined by following relationship

RL 1

1 + KLC0 (8)

where KL (Lmg) is the Langmuir adsorption constant C0(mgL) is the initial MB concentration (e RL valuesclassification is given in Table 6 [61]

34 Freundlich Isotherm (e Freundlichmodel is applicableto describe the multilayer adsorption process on active sites[62]

A linear form of the Freundlich model may be written asfollows

0

20

40

60

80

100

re

mov

al

Time (min)

20mgL30mgL40mgL

0 50 100 150 200 250

Figure 6 Effect of contact time on adsorption of MB ontogeopolymer


ln qe lnKF +1nlnCe (9)

whereKF (mg(1minusn)Lngminus1) is the adsorption capacity and 1n isthe adsorption intensity

35 DubininndashRadushkevich (DndashR) Isotherm (e DndashRisotherm model is a simple model applied to explainthe nature of adsorption on the homogeneous or

heterogeneous surface of an adsorbent and validatedin high concentrations of adsorbate to determine thetype of adsorption (physical or chemical) [63ndash65](e simplified DndashR isotherm equation is expressed asfollows

ln qe ln qm( 1113857minusKε2 (10)

whereK is the DndashR constant of the sorption energy (mol2kJ2)and ε is the Polanyi potential which is given by

ndash8

ndash6

ndash4

ndash2

0

2

4

20mgL30mgL40mgL

Ln (q

e ndash q

t)

Time (min)ndash20 0 20 40 60 80 100 120 140 160 180 200

(a)

0

2

4

6

8

10

12

20mgL30mgL40mgL

tqt

Time (min)0 50 100 150 200 250

(b)

ndash2 0 2 4 6 8 10 12 14 16

0

10

20

30

40

20mgL30mgL40mgL

qt

t12

(c)

Figure 7 Pseudo-first-order (a) Pseudo-second-order (b) and Intraparticle diffusion (c) plots for adsorption of MB by geopolymer

Table 5 Kinetic parameters for the adsorption of MB on geopolymer

Dye C0 (mgL)Pseudo-first-order Pseudo-second-order Intraparticle diffusion model

qexp qe (mgg) k1 (1min) R21 qe (mgg) k2 (gmg min) R2

2 I (mgg) kid (mgg min05) R23

20 1999 843 0045 0875 2041 0031 0999 6042 1198 068330 2993 721 0046 0866 3030 0028 0999 9309 1778 066940 392 1817 0029 0936 40 00098 0999 1164 2334 0692


ε RT ln 1 +1

Ce1113888 1113889 (11)

where T is the temperature (K) R is the gas constant(8314 Jmiddotmolminus1middotKminus1) Ce (mgL) is the equilibrium concen-tration of MB left in solution and qm is the DndashR maximumadsorption capacity

(e value mean energy of sorption E (kJmol) equationcan be calculated from DndashR parameter K as follows

E 1

(2K)

1113968 (12)

(e value of E is useful for estimating the mechanism ofthe adsorption reaction (chemical or physical adsorption)(e value of E between 1 kJmol and 8 kJmol corresponds tophysical adsorption the E value between 8 and 16 kJmolcorresponds to adsorption by chemisorption and when thevalue of E is greater than 16 kJmol adsorption may bedominated by particle diffusion [66 67]

36 Temkin Isotherm (e Temkin isotherm assumes thatthe sorption decreases linearly when the interaction betweenthe surface of the adsorbent and adsorbate increases (elinear Temkin model has been used in the following form[68]

qe BT lnAT + BT lnCe (13)

where BT RTbT bT is the Temkin constant related to heatof sorption (Jmol) AT is the Temkin isotherm constant (Lg) R is the universal gas constant (8314 JmolmiddotK) and T isthe temperature (K)

Figure 10 represents the Langmuir Freundlich Temkinand DubininndashRadushkevich isothermmodels(e constantscalculated from the model equations (Langmuir FreundlichTemkin and DubininndashRadushkevich isotherm) are shownin Table 7 As observed the value of R2 obtained from theLangmuir isotherm equation (0994) was higher than thatfrom the Freundlich (0963) DubininndashRadushkevich (0915)and Temkin (0980) isotherm equations (ese resultsshowed that the adsorption experiments data could be welldescribed by the Langmuir model (e adsorption occurredon the homogeneous surface as a monolayer and themaximum monolayer adsorption capacity (qmax) was foundto be 4348mgg(e RL value was obtained within the range0ltRLlt 1 indicating that the adsorption of cationic dye onthe geopolymer material is favorable In addition Table 8presents a summary of the maximum adsorption capacityqmax of the developed adsorbents for MB dyestuff in theaqueous medium A comparison with other reported ad-sorbents showed that the qmax value for the geopolymer used

AlndashAl

Al

Al

SiO

O O O

OO O

OOO

OO

O

OO

OO

O

OOO O

O

OOOO

O

OOO

O

OO

O OO

O

O

OO

O

O O

OO

OO

O

O O

O

OO

O

O

OO

O

OO

O

O

OO

Olowast

O

OO

OO

O

OO

O

O

O

O

OO

O

O

O O

OO

OO

O

Si

Si Si

Si

Si

Si Si

Si

SiSi

SiSi

Si

SiSi Si

Si

SiSiSi

Si

Si

Si

Si

SiSi

Si

Si

Si Si Si

Si

Si

Si Si

Si

Si

SiAl

Al

Al

AlAlndash

Alndash

AlndashAlndash

Alndash

Alndash

Alndash

Al

Alndash

Alndash

Alndash

Na+Na+

Na+

Na+

Na+

Na+ Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

MB+

MB+

MB+

MB+

MB+ MB+MB+

MB+MB+

MB+

Figure 8 Proposed mechanism for adsorption of methylene blue by geopolymer

0

10

20

30

40

Qe (

mg

g)

Ci (mgL)0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

Figure 9 Effect of initial MB concentration on adsorption capacityof dye on geopolymer

Table 6 Adsorption properties according to RL value

RL Information about adsorptionRL 0 Irreversible0ltRLlt 1 FavorableRL 1 LinearRLgt 1 Unfavorable


in this study is the highest indicating that this new solid is anexcellent adsorbent for the treatment of water containingMB dye

361 Aermodynamic of Adsorption (ermodynamic pa-rameters have an important role to evaluate the phenom-enon of the adsorption process (e thermodynamicparameters namely free energy (ΔGdeg) enthalpy (ΔHdeg) andentropy (ΔSdeg) for adsorption process were obtained usingthe following equations [76]

ΔGdeg minusRT lnqe

Ce

Kd qe

Ce

lnKd ΔSdegRminusΔHdeg

RT

(14)

where qe is the amount of dye adsorbed per unit mass of theadsorbent at equilibrium (mgg) Ce is the equilibrium

00

01

02

03

04

05C e

qe

Ce

0 5 10 15 20

(a)

15

20

25

30

35

40

Ln q

e

Ln Ce

ndash4 ndash3 ndash2 ndash1 0 1 2 3

(b)

0

5

10

15

20

25

30

35

40

45

q e

Ln Ce


(c)

15

20

25

30

35

40

Ln q

e

e20 10000000 20000000 30000000 40000000 50000000 60000000

(d)

Figure 10 Langmuir (a) Freundlich (b) Temkin (c) and DubininndashRadushkevich (d) isotherms for adsorption of MB by geopolymer

Table 7 Models isotherm constants for adsorption of MB using adsorbent

Langmuir Freundlich Temkin DubininndashRadushkevichQm (mgg) KL (Lmg) R2 Range RL KF (mg(1minusn)Lng) 1n R2 AT (Lg) BT R2 Qm (mgg) R2 E (KJmol)4348 115 0994 0014ndash015 1718 0332 0963 4338 5897 0980 3057 0915 577

Table 8 Comparison of the obtained adsorption capacity with thepreviously developed adsorbents in the literature

Adsorbents qmax (mgg) ReferencesKaolin geopolymer 256 [69]Phosphoric acid-based geopolymers 426 [50]fly ash-derived zeolites 1264 [70]Cold plasma-modified kaolin 23 [71]Coal fly ash-based geopolymer 507 [72]Fly ash-based geopolymer 3704 [73]Biomass FA-geopolymer 154 [74]NaOH-treated raw kaolin 1634 [75]Metakaolin-based geopolymer 4348 Present work


concentration (mgL) R is the universal gas constant(8314 Jmiddotmolminus1middotKminus1) and T is the solution temperature (K)

(e values of enthalpy (ΔHdeg) and entropy (ΔSdeg) werecalculated from the slope and intercept of the plot of ln Kdversus 1T (Figure 11) (e thermodynamic parameters formethylene blue adsorption on the composite adsorbent atvarious temperatures are summarized in Table 9 (e pos-itive values of entropy (ΔSdeg) indicate a random increaseduring adsorption (e negative values of enthalpy ΔHdeg

indicate the endothermic nature of the process Moreoverthe values of ΔGdeg determined are negative thus confirmingthat the adsorption process is spontaneous and thermody-namically favorable A similar phenomenon has been ob-served in the adsorption of MB on pomegranate peelactivated carbon [77]

4 Conclusion

In summary a metakaolin-based geopolymer was producedfrom metakaolin and alkali activators and used as an ad-sorbent for cationic dye removal XRF XRD FTIR and SEMstudies show that a geoadsorbent was formed by the geo-polymerization process (e optimum conditions of ad-sorption by geopolymer were found to be a geopolymer massof 01 g in 100mL of MB an initial concentration of MB40mgL a contact time of 120min and a basic pH (ekinetics study of initial concentration demonstrated thatadsorption equilibrium was found to follow the pseudo-second-order equation (e isotherm models data werebetter described by Langmuir isotherm equation with amaximum monolayer adsorption capacity of 4348mgg(e values of the thermodynamic parameters indicatedthat the adsorption was spontaneous and endothermic innature (e overall results prove that the geopolymer has agreat potential and a high selectivity and can be considered

an economical adsorbent for the elimination of methyleneblue from aqueous medium by batch operation

Data Availability

(e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

(e authors declare that they have no conflicts of interest

References

[1] J Pang F Fu Z Ding J Lu N Li and B Tang ldquoAdsorptionbehaviors of methylene blue from aqueous solution onmesoporous birnessiterdquo Journal of the Taiwan Institute ofChemical Engineers vol 77 pp 168ndash176 2017

[2] M Rezaei and S Salem ldquoPhotocatalytic activity enhancementof anatase-graphene nanocomposite for methylene removaldegradation and kineticsrdquo Spectrochimica Acta Part A Mo-lecular and Biomolecular Spectroscopy vol 167 pp 41ndash492016

[3] S Khan and A Malik ldquoEnvironmental and health effects oftextile industry wastewaterrdquo in Environmental Deteriorationand Human Health A Malik E Grohmann and R AkhtarEds Springer Dordrecht Netherlands pp 55ndash71 2014

[4] A Pandey P Singh and L Iyengar ldquoBacterial decolorizationand degradation of azo dyesrdquo International Biodeteriorationamp Biodegradation vol 59 no 2 pp 73ndash84 2007

[5] M Rafatullah O Sulaiman R Hashim and A AhmadldquoAdsorption of methylene blue on low-cost adsorbents areviewrdquo Journal of Hazardous Materials vol 177 no 1ndash3pp 70ndash80 2010

[6] B Shi G Li D Wang C Feng and H Tang ldquoRemoval ofdirect dyes by coagulation the performance of preformedpolymeric aluminum speciesrdquo Journal of Hazardous Mate-rials vol 143 no 1-2 pp 567ndash574 2007

00029 00030 00031 00032 00033 00034 00035

140

145

150

155

160

165

170

175

180

Ln K

d

1T

Figure 11 Enthalpy and entropy change determination of the adsorption of MB by geopolymer

Table 9 (ermodynamic parameters for the adsorption of MB onto geopolymer

Adsorbent Adsorbate ΔHdeg (KJmiddotmolminus1) ΔSdeg (KJmiddotmolminus1middotK1)ΔGdeg (KJmiddotmolminus1)

293K 323K 343KGeopolymer MB 51 003 minus3503 minus4021 minus5048


[7] N Nasuha S Ismail and B H Hameed ldquoActivated electricarc furnace slag as an efficient and reusable heterogeneousfenton-like catalyst for the degradation of reactive black 5rdquoJournal of the Taiwan Institute of Chemical Engineers vol 67pp 235ndash243 2016

[8] Y Zhang and L Liu ldquoFly ash-based geopolymer as a novelphotocatalyst for degradation of dye from wastewaterrdquoParticuology vol 11 no 3 pp 353ndash358 2013

[9] D Jellouli Ennigrou L Gzara M Ramzi Ben Romdhane andM Dhahbi ldquoCadmium removal from aqueous solutions bypolyelectrolyte enhanced ultrafiltrationrdquo Desalinationvol 246 no 1ndash3 pp 363ndash369 2009

[10] A Dabrowski Z Hubicki P Podkoscielny and E RobensldquoSelective removal of the heavy metal ions from waters andindustrial wastewaters by ion-exchange methodrdquo Chemo-sphere vol 56 no 2 pp 91ndash106 2004

[11] I Sires and E Brillas ldquoRemediation of water pollution causedby pharmaceutical residues based on electrochemical sepa-ration and degradation technologies a reviewrdquo EnvironmentInternational vol 40 pp 212ndash229 2012

[12] M El Alouani S Alehyen M E Achouri and M TaibildquoPotential use of moroccan fly ash as low cost adsorbent forthe removal of two anionic dyes (indigo carmine and acidorange)rdquo Journal of Materials and Environmental Sciencesvol 8 pp 3397ndash3409 2017

[13] R Hazzaa and M Hussein ldquoAdsorption of cationic dye fromaqueous solution onto activated carbon prepared from olivestonesrdquo Environmental Technology amp Innovation vol 4pp 36ndash51 2015

[14] Y Liu Y Jiang M Hu S Li and Q Zhai ldquoRemoval oftriphenylmethane dyes by calcium carbonate-lentinan hier-archical mesoporous hybrid materialsrdquo Chemical EngineeringJournal vol 273 pp 371ndash380 2015

[15] M Zbair Z Anfar H Khallok H A Ahsaine M Ezahri andN Elalem ldquoAdsorption kinetics and surface modeling ofaqueous methylene blue onto activated carbonaceous woodsawdustrdquo Fullerenes Nanotubes and Carbon Nanostructuresvol 26 no 7 pp 433ndash442 2018

[16] Y C Wong Y S Szeto W H Cheung and G McKayldquoEquilibrium studies for acid dye adsorption onto chitosanrdquoLangmuir vol 19 no 19 pp 7888ndash7894 2003

[17] L Bulgariu L B Escudero O S Bello et al ldquo(e utilization ofleaf-based adsorbents for dyes removal a reviewrdquo Journal ofMolecular Liquids vol 276 pp 728ndash747 2019

[18] K Rida S Bouraoui and S Hadnine ldquoAdsorption ofmethylene blue from aqueous solution by kaolin and zeoliterdquoApplied Clay Science vol 83-84 pp 99ndash105 2013

[19] V K Gupta R Jain M N Siddiqui et al ldquoEquilibrium andthermodynamic studies on the adsorption of the dyerhodamine-B onto mustard cake and activated carbonrdquoJournal of Chemical amp Engineering Data vol 55 no 11pp 5225ndash5229 2010

[20] H Deng L Yang G Tao and J Dai ldquoPreparation andcharacterization of activated carbon from cotton stalk bymicrowave assisted chemical activation-application inmethylene blue adsorption from aqueous solutionrdquo Journal ofHazardous Materials vol 166 no 2-3 pp 1514ndash1521 2009

[21] S Bentahar A Dbik M E Khomri N E Messaoudi andA Lacherai ldquoAdsorption of methylene blue crystal violet andcongo red from binary and ternary systems with natural claykinetic isotherm and thermodynamicrdquo Journal of Environ-mental Chemical Engineering vol 5 no 6 pp 5921ndash59322017

[22] W Zhao X Huang Y Wang S Sun and C Zhao ldquoA re-cyclable and regenerable magnetic chitosan absorbent for dyeuptakerdquo Carbohydrate Polymers vol 150 pp 201ndash208 2016

[23] S Shakoor and A Nasar ldquoRemoval of methylene blue dyefrom artificially contaminated water using citrus limetta peelwaste as a very low cost adsorbentrdquo Journal of the TaiwanInstitute of Chemical Engineers vol 66 pp 154ndash163 2016

[24] J Sheng Y Xie and Y Zhou ldquoAdsorption of methylene bluefrom aqueous solution on pyrophylliterdquo Applied Clay Sciencevol 46 no 4 pp 422ndash424 2009

[25] Z Liang Z Zhao T Sun W Shi and F Cui ldquoEnhancedadsorption of the cationic dyes in the spherical CuOmeso-silica nano composite and impact of solution chemistryrdquoJournal of Colloid and Interface Science vol 485 pp 192ndash2002017

[26] Z Li G Wang K Zhai C He Q Li and P Guo ldquoMethyleneblue adsorption from aqueous solution by loofah sponge-based porous carbonsrdquo Colloids and Surfaces A Physico-chemical and Engineering Aspects vol 538 pp 28ndash35 2018

[27] J Chang J Ma Q Ma et al ldquoAdsorption of methylene blueonto Fe3O4activated montmorillonite nanocompositerdquo Ap-plied Clay Science vol 119 pp 132ndash140 2016

[28] A A Siyal M R Shamsuddin M I Khan et al ldquoA review ongeopolymers as emerging materials for the adsorption ofheavy metals and dyesrdquo Journal of Environmental Manage-ment vol 224 pp 327ndash339 2018

[29] J Davidovits ldquoGeopolymersrdquo Journal of Aermal Analysisvol 37 no 8 pp 1633ndash1656 1991

[30] J Temuujin R P Williams and A van Riessen ldquoEffect ofmechanical activation of fly ash on the properties of geo-polymer cured at ambient temperaturerdquo Journal of MaterialsProcessing Technology vol 209 no 12-13 pp 5276ndash52802009

[31] T R Barbosa E L Foletto G L Dotto and S L JahnldquoPreparation of mesoporous geopolymer using metakaolinand rice husk ash as synthesis precursors and its use as po-tential adsorbent to remove organic dye from aqueous so-lutionsrdquo Ceramics International vol 44 no 1 pp 416ndash4232018

[32] Y J Zhang L C Liu Y Xu Y CWang and D L Xu ldquoA newalkali-activated steel slag-based cementitious material forphotocatalytic degradation of organic pollutant from wastewaterrdquo Journal of Hazardous Materials vol 209-210pp 146ndash150 2012

[33] S Alehyen M Zerzouri M EL Alouani M EL Achouri andM Taibi ldquoPorosity and fire resistance of fly ash based geo-polymerrdquo Journal of Materials and Environmental Sciencesvol 9 pp 3676ndash3689 2017

[34] R R Pawar B H C Lalhmunsiama H C Bajaj andS-M Lee ldquoActivated bentonite as a low-cost adsorbent for theremoval of Cu(II) and Pb(II) from aqueous solutions batchand column studiesrdquo Journal of Industrial and EngineeringChemistry vol 34 pp 213ndash223 2016

[35] G S Ryu Y B Lee K T Koh and Y S Chung ldquo(emechanical properties of fly ash-based geopolymer concretewith alkaline activatorsrdquo Construction and Building Materialsvol 47 pp 409ndash418 2013

[36] Q Wan F Rao S Song D F Cholico-Gonzalez andN L Ortiz ldquoCombination formation in the reinforcement ofmetakaolin geopolymers with quartz sandrdquo Cement andConcrete Composites vol 80 pp 115ndash122 2017

[37] M Jin Z Zheng Y Sun L Chen and Z Jin ldquoResistance ofmetakaolin-MSWI fly ash based geopolymer to acid and


alkaline environmentsrdquo Journal of Non-Crystalline Solidsvol 450 pp 116ndash122 2016

[38] F G M Aredes T M B Campos J P B MachadoK K Sakane G P (im and D D Brunelli ldquoEffect of curetemperature on the formation of metakaolinite-based geo-polymerrdquo Ceramics International vol 41 no 6 pp 7302ndash7311 2015

[39] J C Swanepoel and C A Strydom ldquoUtilisation of fly ash in ageopolymeric materialrdquo Applied Geochemistry vol 17 no 8pp 1143ndash1148 2002

[40] A Boukhemkhem and K Rida ldquoImprovement adsorptioncapacity of methylene blue onto modified tamazert kaolinrdquoAdsorption Science amp Technology vol 35 no 9-10 pp 753ndash773 2017

[41] N Belmokhtar M Ammari J Brigui and L Ben AllalldquoComparison of the microstructure and the compressivestrength of two geopolymers derived from metakaolin and anindustrial sludgerdquo Construction and Building Materialsvol 146 pp 621ndash629 2017

[42] C M Muller B Pejcic L Esteban C D Piane M Raven andB Mizaikoff ldquoInfrared attenuated total reflectance spectros-copy an innovative strategy for analyzing mineral compo-nents in energy relevant systemsrdquo Scientific Reports vol 4no 1 p 6764 2014

[43] T Bakharev ldquoResistance of geopolymer materials to acidattackrdquo Cement and Concrete Research vol 35 no 4pp 658ndash670 2005

[44] W K W Lee and J S J van Deventer ldquo(e effects of in-organic salt contamination on the strength and durability ofgeopolymersrdquo Colloids and Surfaces A Physicochemical andEngineering Aspects vol 211 no 2-3 pp 115ndash126 2002

[45] I Kara D Yilmazer and S T Akar ldquoMetakaolin basedgeopolymer as an effective adsorbent for adsorption ofzinc(II) and nickel(II) ions from aqueous solutionsrdquo AppliedClay Science vol 139 pp 54ndash63 2017

[46] D Krizan and B Zivanovic ldquoEffects of dosage and modulus ofwater glass on early hydration of alkali-slag cementsrdquo Cementand Concrete Research vol 32 no 8 pp 1181ndash1188 2002

[47] L Chen Z Wang Y Wang and J Feng ldquoPreparation andproperties of alkali activated metakaolin-based geopolymerrdquoMaterials vol 9 no 9 p 767 2016

[48] C P J Isaac and A Sivakumar ldquoRemoval of lead and cad-mium ions from water usingAnnona squamosashell kineticand equilibrium studiesrdquo Desalination and Water Treatmentvol 51 no 40ndash42 pp 7700ndash7709 2013

[49] A Maleki M Mohammad Z Emdadi N AsimM Azizi andJ Safaei ldquoAdsorbent materials based on a geopolymer pastefor dye removal from aqueous solutionsrdquo Arabian Journal ofChemistry 2018 In press

[50] M I Khan T K Min K Azizli S Sufian H Ullah andZ Man ldquoEffective removal of methylene blue from waterusing phosphoric acid based geopolymers synthesis char-acterizations and adsorption studiesrdquo RSC Advances vol 5no 75 pp 61410ndash61420 2015

[51] D Kavitha and C Namasivayam ldquoExperimental and kineticstudies on methylene blue adsorption by coir pith carbonrdquoBioresource Technology vol 98 no 1 pp 14ndash21 2007

[52] S M de Oliveira Brito H M C Andrade L F Soares andR P de Azevedo ldquoBrazil nut shells as a new biosorbent toremove methylene blue and indigo carmine from aqueoussolutionsrdquo Journal of Hazardous Materials vol 174 no 1ndash3pp 84ndash92 2010

[53] S A Hamid M Shahadat and S Ismail ldquoDevelopment ofcost effective bentonite adsorbent coating for the removal of

organic pollutantrdquo Applied Clay Science vol 149 pp 79ndash862017

[54] S Lagergren ldquoZur theorie der sogenannten adsorptiongeloster stofferdquo Kungliga Svenska VetenskapsakademiensHandlingar vol 24 pp 1ndash39 1898

[55] Y S Ho and G McKay ldquoPseudo-second order model forsorption processesrdquo Process Biochemistry vol 34 no 5pp 451ndash465 1999

[56] J F Baret ldquoKinetics of adsorption from a solution Role of thediffusion and of the adsorption-desorption antagonismrdquoJournal of Physical Chemistry vol 72 no 8 pp 2755ndash27581968

[57] A Baraka ldquoAdsorptive removal of tartrazine and methyleneblue from wastewater using melamine-formaldehyde-tartaricacid resin (and a discussion about pseudo second ordermodel)rdquo Desalination and Water Treatment vol 44 no 1ndash3pp 128ndash141 2012

[58] J Hu W Dai and X Yan ldquoComparison study on the ad-sorption performance of methylene blue and congo red onCu-BTCrdquo Desalination and Water Treatment vol 57 no 9pp 4081ndash4089 2016

[59] X Peng D Huang T Odoom-Wubah D Fu J Huang andQ Qin ldquoAdsorption of anionic and cationic dyes on ferro-magnetic ordered mesoporous carbon from aqueous solutionequilibrium thermodynamic and kineticsrdquo Journal of Colloidand Interface Science vol 430 pp 272ndash282 2014

[60] D Singh S K Singh N Atar and V Krishna ldquoAmino acidfunctionalized magnetic nanoparticles for removal of Ni(II)from aqueous solutionrdquo Journal of the Taiwan Institute ofChemical Engineers vol 67 pp 148ndash160 2016

[61] T W Weber and R K Chakravorti ldquoPore and solid diffusionmodels for fixed-bed adsorbersrdquoAIChE Journal vol 20 no 2pp 228ndash238 1974

[62] H Freundlich and W Heller ldquo(e Adsorption ofcis- andtrans-azobenzenerdquo Journal of the American Chemical Societyvol 61 no 8 pp 2228ndash2230 1939

[63] M M Dubinin E Zaverina and L Radushkevich ldquoSorptionand structure of active carbons I Adsorption of organicvaporsrdquo Zhurnal Fizicheskoi Khimii vol 21 pp 151ndash1621947

[64] F Ouadjenia-Marouf R Marouf J Schott and A YahiaouildquoRemoval of Cu(II) Cd(II) and Cr(III) ions from aqueoussolution by dam siltrdquo Arabian Journal of Chemistry vol 6no 4 pp 401ndash406 2013

[65] H Zheng D Liu Y Zheng S Liang and Z Liu ldquoSorptionisotherm and kinetic modeling of aniline on Cr-bentoniterdquoJournal of Hazardous Materials vol 167 no 1ndash3 pp 141ndash1472009

[66] K Saltalı A Sarı and M Aydın ldquoRemoval of ammonium ionfrom aqueous solution by natural Turkish (Yıldızeli) zeolitefor environmental qualityrdquo Journal of Hazardous Materialsvol 141 pp 258ndash263 2007

[67] A Sarı M Tuzen D Cıtak and M Soylak ldquoAdsorptioncharacteristics of Cu(II) and Pb(II) onto expanded perlitefrom aqueous solutionrdquo Journal of Hazardous Materialsvol 148 pp 387ndash394 2007

[68] F Rozada M Otero A I Garcıa and A Moran ldquoApplicationin fixed-bed systems of adsorbents obtained from sewagesludge and discarded tyresrdquo Dyes and Pigments vol 72 no 1pp 47ndash56 2007

[69] R I Yousef B El-Eswed M Alshaaer F Khalili andH Khoury ldquo(e influence of using Jordanian natural zeoliteon the adsorption physical and mechanical properties of


geopolymers productsrdquo Journal of Hazardous Materialsvol 165 no 1-3 pp 379ndash387 2009

[70] C D Woolard J Strong and C R Erasmus ldquoEvaluation ofthe use of modified coal ash as a potential sorbent for organicwaste streamsrdquo Applied Geochemistry vol 17 no 8pp 1159ndash1164 2002

[71] O Yavuz and C Saka ldquoSurface modification with cold plasmaapplication on kaolin and its effects on the adsorption ofmethylene bluerdquo Applied Clay Science vol 85 pp 96ndash1022013

[72] Y Liu C Yan Z Zhang Y Gong H Wang and X Qiu ldquoAfacile method for preparation of floatable and permeable flyash-based geopolymer blockrdquo Materials Letters vol 185pp 370ndash373 2016

[73] M EL Alouani S Alehyen M EL Achouri and M TaibildquoRemoval of cationic dyemdashmethylene bluemdashfrom aqueoussolution by adsorption on fly ashmdashbased geopolymerrdquoJournal of Materials and Environmental Sciences vol 9 no 1pp 32ndash46 2018

[74] R M Novais G Ascensatildeo D M Tobaldi M P Seabra andJ A Labrincha ldquoBiomass fly ash geopolymer monoliths foreffective methylene blue removal from wastewatersrdquo Journalof Cleaner Production vol 171 pp 783ndash794 2018

[75] D Ghosh and K G Bhattacharyya ldquoAdsorption of methyleneblue on kaoliniterdquo Applied Clay Science vol 20 no 6pp 295ndash300 2002

[76] S A Drweesh N A Fathy M A Wahba et al ldquoEquilibriumkinetic and thermodynamic studies of Pb(II) adsorption fromaqueous solutions on HCl-treated Egyptian kaolinrdquo Journal ofEnvironmental Chemical Engineering vol 4 no 2pp 1674ndash1684 2016

[77] M A Ahmad N A Ahmad Puad and O S Bello ldquoKineticequilibrium and thermodynamic studies of synthetic dyeremoval using pomegranate peel activated carbon prepared bymicrowave-induced KOH activationrdquo Water Resources andIndustry vol 6 pp 18ndash35 2014


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nom

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Submit your manuscripts atwwwhindawicom

adsorption is a technique of choice due to its low cost simpledesign and reusability [16 17] Different categories of naturaland synthetic adsorbents were utilized for the removal of thisorganic material from aquatic media such as kaolin [18]zeolite [19] activated carbon [20] mesoporous birnessite [1]natural clay [21] magnetic chitosan [22] fruit peels [23]biochar microparticles [24] silica [25] loofah sponge-basedporous carbons [26] pyrophyllite [24] and Fe3O4activatedmontmorillonite nanocomposite [27] Among the synthesizedadsorbents mostly used to remove organic matters are geo-polymers [28] Geopolymers firstly named by Joseph Davi-dovits [29] are formed by activation of aluminosilicateprecursors and these solids can be natural (kaolin micaandalusite spinelle illite or Slag Hill) or synthetic (meta-kaolin fly ash calcined by-products or industrial residues)activated by alkali silicate solution (typically Na or K) attemperatures between 20degC and 100degC [30] Corresponding todifferent SiAl ratios the materials are composed of networkstructures of (Na K)-poly(sialate) (-O-Si-O-Al-O-)n (Na K)-poly(sialat-siloxo) (-O-Si-O-Al-O-Si-O)n and (Na K)-poly(sialate-disiloxo) (O-Si-O-Al-O-Si-O-Si-O-)n [29] (egeopolymers or inorganic polymers have also gained signifi-cant attention as efficient adsorbents with good physical andchemical properties Recently several studies were conductedin the interest of activation of aluminosilicate precursorscharacterized and tested for removal of dyestuffs and haz-ardous materials from aquatic environment [8 31 32]

In this work a geopolymerization method was applied tosynthesize the metakaolin-based geopolymer (e structuraland morphological properties of the elaborated adsorbentwere characterized by XRF XRD FTIR and SEM analyses(e adsorption properties of the elaborated sample werestudied in different experimental conditions includingadsorbent mass pH contact time initial dye solution andtemperature (e adsorption kinetics isotherms and ther-modynamics data of the adsorption were investigated tostudy the batch adsorption process of the basic dye using thesynthesized metakaolin-based geopolymer

2 Materials and Experimental Methods

21Materials andChemicals Kaolin was collected from BabMssila situated at Ribat El Kheir next to Sefrou city in thenorthwest of Morocco (e raw clay was subjected to cal-cination at temperatures of 800degC for 3 h

(e industrial-grade sodium silicate powder (Honey-well Riedel-de Haen Germany 18 wt Na2O 63 wtSiO2 18 wt loss on ignition) and commercial sodiumhydroxide (NaOH 99 purity) (ACS AR-grade pellets)were provided by Sigma-Aldrich Methylene blue (MB) dyewith the chemical composition C16H18ClN3S and a MW of319852 gmol was supplied by Sigma-Aldrich

22 Geopolymer Synthesis (e geopolymer sample wassynthesized in several steps (e first step was to synthesizethe activator solution by initially dissolving Na2SiO3 powderand sodium hydroxide NaOH (12M) at a mass ratio of 25[33] (e mixture was stirred at room temperature for a

period of 15min (e second step of the elaboration is themixing of metakaolin with the activator solution which wasconducted using in a mixer with constant stirring at ambienttemperature for 15min to obtain good homogenization(en distilled water was added at a ratio watermetakaolinof 034 to obtain the desired workability of the geopolymerpaste (e mixture was placed in a cylindrical mould andtreated at 60degC for 24 hours Finally the matrix was sieved toparticle sizes lt200 μm and stored in a desiccator for char-acterization and investigation of the adsorption tests (emix proportions of the metakaolin-based geopolymer pastesare displayed in Table 1

23 Adsorption Experiments A series of batch adsorptionexperiments were carried out under different operatingconditions related to adsorbent mass (005ndash035 g) contacttime (0ndash220min) initial solution pH (2ndash13) initial dyeconcentration (5ndash60mgL) and temperature (20ndash70degC) at aconstant agitation speed (250 rpm) (Table 2) (e solutionpH was adjusted to optimum values using 01M NaOH or01M HCl Afterwards the sample was centrifuged at2500 rpm for 10min (e initial and the residual concen-trations of MB were measured using a spectrophotometer ata wavelength of 664 nm (e removal efficiency of themetakaolin-based geopolymer was calculated using equation(1) adsorption capacity at any time qt (mgmiddotgminus1) was obtainedusing equation (2) and adsorption capacity at equilibrium qe(mgmiddotgminus1) was determined using equation (3)

removal Ci minusCt( 1113857

Ci

times 100 (1)

qt Ci minusCt( 1113857

mV (2)

qe Ci minusCe( 1113857

mV (3)

where Ci (mgmiddotLminus1) is the initial concentration of MB solu-tion Ce (mgmiddotLminus1) and Ct (mgmiddotLminus1) are respectively theliquid-phase concentration of MB at initial time and at anytime t after the adsorption process m (g) is the weight ofgeopolymer and V (L) is the volume of the MB solution

24 Instrument Analysis (e chemical compositions ofmaterials and the prepared adsorbent were determined byX-ray fluorescence using a spectrometer dispersionwavelength-type Axios (e crystalline phases of the samplewere detected using an X-ray diffractometer (Philips model1840 equipment) (e functional groups of samples weredetected using Fourier-transform infrared spectrometrybruker platinum ATR apparatus in the range of 4000ndash400 cmminus1 wavelengths (e microstructure of metakaolinand metakaolin-based geopolymer was observed using theJEOL-6300F field-scanning electron microscope (SEMEDX) (e concentration of MB was determined usingthe spectrophotometer JASCO V-630 UVVIS A pH-metermodel (M 210) was used for pH measurement










Metakaolin(g)

NaOH(g)

Silicate(g)


Extrawater (g)

Totalwater(g)



RatioNa2SiO3NaOH

Massratio (g) 50 5715 14285 11905 5 16905 034 25 25




005

120 40

010150202503035


0

20 30 40

306090120150180220

pH 25

221

01 120 40

44661680910061206


5 01 120 405070


510204060








10 20 30 40 50

QQK

K

Q

Q

Q

2θ (deg)


Q

KKK

Q

K

K


4000 3500 3000 2500 2000 1500 1000 500

446

556

446

1111

979

988

1622

437

532

593

757

662

988

1151

1436

6153410

Tran

smitt

ance

()



3550









(cps

eV

)

45

40

35

30

25

20

15

105

01 2 3 4 5

Energy (keV)


6 7 8 9 10

E1 2960

(a)

(cps

eV

)

45

40

35

30

25

20

15

10

5

02 4 6 8



E2 2968

(b)










000 005 010 015 020 025 030 035 04040

60

80

100

re

mov

al

Mass (g)


2 4 6 8 10 1260

65

70

75

80

85

90

95

100

re

mov

al

pH

(a)

2 4 6 8 10 12 14

ndash5

ndash4

ndash3

ndash2

ndash1

0

1

2

pHI ndash

pH

F

pHIpHpzc = 9

(b)







t

qt

1k2q

2e

+t

qe (5)


qt kIt12

+ I (6)








Ce

qe

1KLqm

+Ce

qm (7)



RL 1

1 + KLC0 (8)




0

20

40

60

80

100

re

mov

al

Time (min)

20mgL30mgL40mgL

0 50 100 150 200 250









ndash8

ndash6

ndash4

ndash2

0

2

4

20mgL30mgL40mgL

Ln (q

e ndash q

t)

Time (min)ndash20 0 20 40 60 80 100 120 140 160 180 200

(a)

0

2

4

6

8

10

12

20mgL30mgL40mgL

tqt

Time (min)0 50 100 150 200 250

(b)

ndash2 0 2 4 6 8 10 12 14 16

0

10

20

30

40

20mgL30mgL40mgL

qt

t12

(c)






20 1999 843 0045 0875 2041 0031 0999 6042 1198 068330 2993 721 0046 0866 3030 0028 0999 9309 1778 066940 392 1817 0029 0936 40 00098 0999 1164 2334 0692


ε RT ln 1 +1

Ce1113888 1113889 (11)



E 1

(2K)

1113968 (12)






AlndashAl

Al

Al

SiO

O O O

OO O

OOO

OO

O

OO

OO

O

OOO O

O

OOOO

O

OOO

O

OO

O OO

O

O

OO

O

O O

OO

OO

O

O O

O

OO

O

O

OO

O

OO

O

O

OO

Olowast

O

OO

OO

O

OO

O

O

O

O

OO

O

O

O O

OO

OO

O

Si

Si Si

Si

Si

Si Si

Si

SiSi

SiSi

Si

SiSi Si

Si

SiSiSi

Si

Si

Si

Si

SiSi

Si

Si

Si Si Si

Si

Si

Si Si

Si

Si

SiAl

Al

Al

AlAlndash

Alndash

AlndashAlndash

Alndash

Alndash

Alndash

Al

Alndash

Alndash

Alndash

Na+Na+

Na+

Na+

Na+

Na+ Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

MB+

MB+

MB+

MB+

MB+ MB+MB+

MB+MB+

MB+


0

10

20

30

40

Qe (

mg

g)

Ci (mgL)0 5 10 15 20 25 30 35 40 45 50 55 60 65 70







ΔGdeg minusRT lnqe

Ce

Kd qe

Ce


RT

(14)


00

01

02

03

04

05C e

qe

Ce

0 5 10 15 20

(a)

15

20

25

30

35

40

Ln q

e

Ln Ce


(b)

0

5

10

15

20

25

30

35

40

45

q e

Ln Ce


(c)

15

20

25

30

35

40

Ln q

e

e20 10000000 20000000 30000000 40000000 50000000 60000000

(d)










4 Conclusion



Data Availability




References







00029 00030 00031 00032 00033 00034 00035

140

145

150

155

160

165

170

175

180

Ln K

d

1T
























































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls












Metakaolin(g)

NaOH(g)

Silicate(g)


Extrawater (g)

Totalwater(g)



RatioNa2SiO3NaOH

Massratio (g) 50 5715 14285 11905 5 16905 034 25 25




005

120 40

010150202503035


0

20 30 40

306090120150180220

pH 25

221

01 120 40

44661680910061206


5 01 120 405070


510204060








10 20 30 40 50

QQK

K

Q

Q

Q

2θ (deg)


Q

KKK

Q

K

K


4000 3500 3000 2500 2000 1500 1000 500

446

556

446

1111

979

988

1622

437

532

593

757

662

988

1151

1436

6153410

Tran

smitt

ance

()



3550









(cps

eV

)

45

40

35

30

25

20

15

105

01 2 3 4 5

Energy (keV)


6 7 8 9 10

E1 2960

(a)

(cps

eV

)

45

40

35

30

25

20

15

10

5

02 4 6 8



E2 2968

(b)










000 005 010 015 020 025 030 035 04040

60

80

100

re

mov

al

Mass (g)


2 4 6 8 10 1260

65

70

75

80

85

90

95

100

re

mov

al

pH

(a)

2 4 6 8 10 12 14

ndash5

ndash4

ndash3

ndash2

ndash1

0

1

2

pHI ndash

pH

F

pHIpHpzc = 9

(b)







t

qt

1k2q

2e

+t

qe (5)


qt kIt12

+ I (6)








Ce

qe

1KLqm

+Ce

qm (7)



RL 1

1 + KLC0 (8)




0

20

40

60

80

100

re

mov

al

Time (min)

20mgL30mgL40mgL

0 50 100 150 200 250









ndash8

ndash6

ndash4

ndash2

0

2

4

20mgL30mgL40mgL

Ln (q

e ndash q

t)

Time (min)ndash20 0 20 40 60 80 100 120 140 160 180 200

(a)

0

2

4

6

8

10

12

20mgL30mgL40mgL

tqt

Time (min)0 50 100 150 200 250

(b)

ndash2 0 2 4 6 8 10 12 14 16

0

10

20

30

40

20mgL30mgL40mgL

qt

t12

(c)






20 1999 843 0045 0875 2041 0031 0999 6042 1198 068330 2993 721 0046 0866 3030 0028 0999 9309 1778 066940 392 1817 0029 0936 40 00098 0999 1164 2334 0692


ε RT ln 1 +1

Ce1113888 1113889 (11)



E 1

(2K)

1113968 (12)






AlndashAl

Al

Al

SiO

O O O

OO O

OOO

OO

O

OO

OO

O

OOO O

O

OOOO

O

OOO

O

OO

O OO

O

O

OO

O

O O

OO

OO

O

O O

O

OO

O

O

OO

O

OO

O

O

OO

Olowast

O

OO

OO

O

OO

O

O

O

O

OO

O

O

O O

OO

OO

O

Si

Si Si

Si

Si

Si Si

Si

SiSi

SiSi

Si

SiSi Si

Si

SiSiSi

Si

Si

Si

Si

SiSi

Si

Si

Si Si Si

Si

Si

Si Si

Si

Si

SiAl

Al

Al

AlAlndash

Alndash

AlndashAlndash

Alndash

Alndash

Alndash

Al

Alndash

Alndash

Alndash

Na+Na+

Na+

Na+

Na+

Na+ Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

MB+

MB+

MB+

MB+

MB+ MB+MB+

MB+MB+

MB+


0

10

20

30

40

Qe (

mg

g)

Ci (mgL)0 5 10 15 20 25 30 35 40 45 50 55 60 65 70







ΔGdeg minusRT lnqe

Ce

Kd qe

Ce


RT

(14)


00

01

02

03

04

05C e

qe

Ce

0 5 10 15 20

(a)

15

20

25

30

35

40

Ln q

e

Ln Ce


(b)

0

5

10

15

20

25

30

35

40

45

q e

Ln Ce


(c)

15

20

25

30

35

40

Ln q

e

e20 10000000 20000000 30000000 40000000 50000000 60000000

(d)










4 Conclusion



Data Availability




References







00029 00030 00031 00032 00033 00034 00035

140

145

150

155

160

165

170

175

180

Ln K

d

1T
























































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls










10 20 30 40 50

QQK

K

Q

Q

Q

2θ (deg)


Q

KKK

Q

K

K


4000 3500 3000 2500 2000 1500 1000 500

446

556

446

1111

979

988

1622

437

532

593

757

662

988

1151

1436

6153410

Tran

smitt

ance

()



3550









(cps

eV

)

45

40

35

30

25

20

15

105

01 2 3 4 5

Energy (keV)


6 7 8 9 10

E1 2960

(a)

(cps

eV

)

45

40

35

30

25

20

15

10

5

02 4 6 8



E2 2968

(b)










000 005 010 015 020 025 030 035 04040

60

80

100

re

mov

al

Mass (g)


2 4 6 8 10 1260

65

70

75

80

85

90

95

100

re

mov

al

pH

(a)

2 4 6 8 10 12 14

ndash5

ndash4

ndash3

ndash2

ndash1

0

1

2

pHI ndash

pH

F

pHIpHpzc = 9

(b)







t

qt

1k2q

2e

+t

qe (5)


qt kIt12

+ I (6)








Ce

qe

1KLqm

+Ce

qm (7)



RL 1

1 + KLC0 (8)




0

20

40

60

80

100

re

mov

al

Time (min)

20mgL30mgL40mgL

0 50 100 150 200 250









ndash8

ndash6

ndash4

ndash2

0

2

4

20mgL30mgL40mgL

Ln (q

e ndash q

t)

Time (min)ndash20 0 20 40 60 80 100 120 140 160 180 200

(a)

0

2

4

6

8

10

12

20mgL30mgL40mgL

tqt

Time (min)0 50 100 150 200 250

(b)

ndash2 0 2 4 6 8 10 12 14 16

0

10

20

30

40

20mgL30mgL40mgL

qt

t12

(c)






20 1999 843 0045 0875 2041 0031 0999 6042 1198 068330 2993 721 0046 0866 3030 0028 0999 9309 1778 066940 392 1817 0029 0936 40 00098 0999 1164 2334 0692


ε RT ln 1 +1

Ce1113888 1113889 (11)



E 1

(2K)

1113968 (12)






AlndashAl

Al

Al

SiO

O O O

OO O

OOO

OO

O

OO

OO

O

OOO O

O

OOOO

O

OOO

O

OO

O OO

O

O

OO

O

O O

OO

OO

O

O O

O

OO

O

O

OO

O

OO

O

O

OO

Olowast

O

OO

OO

O

OO

O

O

O

O

OO

O

O

O O

OO

OO

O

Si

Si Si

Si

Si

Si Si

Si

SiSi

SiSi

Si

SiSi Si

Si

SiSiSi

Si

Si

Si

Si

SiSi

Si

Si

Si Si Si

Si

Si

Si Si

Si

Si

SiAl

Al

Al

AlAlndash

Alndash

AlndashAlndash

Alndash

Alndash

Alndash

Al

Alndash

Alndash

Alndash

Na+Na+

Na+

Na+

Na+

Na+ Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

MB+

MB+

MB+

MB+

MB+ MB+MB+

MB+MB+

MB+


0

10

20

30

40

Qe (

mg

g)

Ci (mgL)0 5 10 15 20 25 30 35 40 45 50 55 60 65 70







ΔGdeg minusRT lnqe

Ce

Kd qe

Ce


RT

(14)


00

01

02

03

04

05C e

qe

Ce

0 5 10 15 20

(a)

15

20

25

30

35

40

Ln q

e

Ln Ce


(b)

0

5

10

15

20

25

30

35

40

45

q e

Ln Ce


(c)

15

20

25

30

35

40

Ln q

e

e20 10000000 20000000 30000000 40000000 50000000 60000000

(d)










4 Conclusion



Data Availability




References







00029 00030 00031 00032 00033 00034 00035

140

145

150

155

160

165

170

175

180

Ln K

d

1T
























































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls










(cps

eV

)

45

40

35

30

25

20

15

105

01 2 3 4 5

Energy (keV)


6 7 8 9 10

E1 2960

(a)

(cps

eV

)

45

40

35

30

25

20

15

10

5

02 4 6 8



E2 2968

(b)










000 005 010 015 020 025 030 035 04040

60

80

100

re

mov

al

Mass (g)


2 4 6 8 10 1260

65

70

75

80

85

90

95

100

re

mov

al

pH

(a)

2 4 6 8 10 12 14

ndash5

ndash4

ndash3

ndash2

ndash1

0

1

2

pHI ndash

pH

F

pHIpHpzc = 9

(b)







t

qt

1k2q

2e

+t

qe (5)


qt kIt12

+ I (6)








Ce

qe

1KLqm

+Ce

qm (7)



RL 1

1 + KLC0 (8)




0

20

40

60

80

100

re

mov

al

Time (min)

20mgL30mgL40mgL

0 50 100 150 200 250









ndash8

ndash6

ndash4

ndash2

0

2

4

20mgL30mgL40mgL

Ln (q

e ndash q

t)

Time (min)ndash20 0 20 40 60 80 100 120 140 160 180 200

(a)

0

2

4

6

8

10

12

20mgL30mgL40mgL

tqt

Time (min)0 50 100 150 200 250

(b)

ndash2 0 2 4 6 8 10 12 14 16

0

10

20

30

40

20mgL30mgL40mgL

qt

t12

(c)






20 1999 843 0045 0875 2041 0031 0999 6042 1198 068330 2993 721 0046 0866 3030 0028 0999 9309 1778 066940 392 1817 0029 0936 40 00098 0999 1164 2334 0692


ε RT ln 1 +1

Ce1113888 1113889 (11)



E 1

(2K)

1113968 (12)






AlndashAl

Al

Al

SiO

O O O

OO O

OOO

OO

O

OO

OO

O

OOO O

O

OOOO

O

OOO

O

OO

O OO

O

O

OO

O

O O

OO

OO

O

O O

O

OO

O

O

OO

O

OO

O

O

OO

Olowast

O

OO

OO

O

OO

O

O

O

O

OO

O

O

O O

OO

OO

O

Si

Si Si

Si

Si

Si Si

Si

SiSi

SiSi

Si

SiSi Si

Si

SiSiSi

Si

Si

Si

Si

SiSi

Si

Si

Si Si Si

Si

Si

Si Si

Si

Si

SiAl

Al

Al

AlAlndash

Alndash

AlndashAlndash

Alndash

Alndash

Alndash

Al

Alndash

Alndash

Alndash

Na+Na+

Na+

Na+

Na+

Na+ Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

MB+

MB+

MB+

MB+

MB+ MB+MB+

MB+MB+

MB+


0

10

20

30

40

Qe (

mg

g)

Ci (mgL)0 5 10 15 20 25 30 35 40 45 50 55 60 65 70







ΔGdeg minusRT lnqe

Ce

Kd qe

Ce


RT

(14)


00

01

02

03

04

05C e

qe

Ce

0 5 10 15 20

(a)

15

20

25

30

35

40

Ln q

e

Ln Ce


(b)

0

5

10

15

20

25

30

35

40

45

q e

Ln Ce


(c)

15

20

25

30

35

40

Ln q

e

e20 10000000 20000000 30000000 40000000 50000000 60000000

(d)










4 Conclusion



Data Availability




References







00029 00030 00031 00032 00033 00034 00035

140

145

150

155

160

165

170

175

180

Ln K

d

1T
























































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls











000 005 010 015 020 025 030 035 04040

60

80

100

re

mov

al

Mass (g)


2 4 6 8 10 1260

65

70

75

80

85

90

95

100

re

mov

al

pH

(a)

2 4 6 8 10 12 14

ndash5

ndash4

ndash3

ndash2

ndash1

0

1

2

pHI ndash

pH

F

pHIpHpzc = 9

(b)







t

qt

1k2q

2e

+t

qe (5)


qt kIt12

+ I (6)








Ce

qe

1KLqm

+Ce

qm (7)



RL 1

1 + KLC0 (8)




0

20

40

60

80

100

re

mov

al

Time (min)

20mgL30mgL40mgL

0 50 100 150 200 250









ndash8

ndash6

ndash4

ndash2

0

2

4

20mgL30mgL40mgL

Ln (q

e ndash q

t)

Time (min)ndash20 0 20 40 60 80 100 120 140 160 180 200

(a)

0

2

4

6

8

10

12

20mgL30mgL40mgL

tqt

Time (min)0 50 100 150 200 250

(b)

ndash2 0 2 4 6 8 10 12 14 16

0

10

20

30

40

20mgL30mgL40mgL

qt

t12

(c)






20 1999 843 0045 0875 2041 0031 0999 6042 1198 068330 2993 721 0046 0866 3030 0028 0999 9309 1778 066940 392 1817 0029 0936 40 00098 0999 1164 2334 0692


ε RT ln 1 +1

Ce1113888 1113889 (11)



E 1

(2K)

1113968 (12)






AlndashAl

Al

Al

SiO

O O O

OO O

OOO

OO

O

OO

OO

O

OOO O

O

OOOO

O

OOO

O

OO

O OO

O

O

OO

O

O O

OO

OO

O

O O

O

OO

O

O

OO

O

OO

O

O

OO

Olowast

O

OO

OO

O

OO

O

O

O

O

OO

O

O

O O

OO

OO

O

Si

Si Si

Si

Si

Si Si

Si

SiSi

SiSi

Si

SiSi Si

Si

SiSiSi

Si

Si

Si

Si

SiSi

Si

Si

Si Si Si

Si

Si

Si Si

Si

Si

SiAl

Al

Al

AlAlndash

Alndash

AlndashAlndash

Alndash

Alndash

Alndash

Al

Alndash

Alndash

Alndash

Na+Na+

Na+

Na+

Na+

Na+ Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

MB+

MB+

MB+

MB+

MB+ MB+MB+

MB+MB+

MB+


0

10

20

30

40

Qe (

mg

g)

Ci (mgL)0 5 10 15 20 25 30 35 40 45 50 55 60 65 70







ΔGdeg minusRT lnqe

Ce

Kd qe

Ce


RT

(14)


00

01

02

03

04

05C e

qe

Ce

0 5 10 15 20

(a)

15

20

25

30

35

40

Ln q

e

Ln Ce


(b)

0

5

10

15

20

25

30

35

40

45

q e

Ln Ce


(c)

15

20

25

30

35

40

Ln q

e

e20 10000000 20000000 30000000 40000000 50000000 60000000

(d)










4 Conclusion



Data Availability




References







00029 00030 00031 00032 00033 00034 00035

140

145

150

155

160

165

170

175

180

Ln K

d

1T
























































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls








t

qt

1k2q

2e

+t

qe (5)


qt kIt12

+ I (6)








Ce

qe

1KLqm

+Ce

qm (7)



RL 1

1 + KLC0 (8)




0

20

40

60

80

100

re

mov

al

Time (min)

20mgL30mgL40mgL

0 50 100 150 200 250









ndash8

ndash6

ndash4

ndash2

0

2

4

20mgL30mgL40mgL

Ln (q

e ndash q

t)

Time (min)ndash20 0 20 40 60 80 100 120 140 160 180 200

(a)

0

2

4

6

8

10

12

20mgL30mgL40mgL

tqt

Time (min)0 50 100 150 200 250

(b)

ndash2 0 2 4 6 8 10 12 14 16

0

10

20

30

40

20mgL30mgL40mgL

qt

t12

(c)






20 1999 843 0045 0875 2041 0031 0999 6042 1198 068330 2993 721 0046 0866 3030 0028 0999 9309 1778 066940 392 1817 0029 0936 40 00098 0999 1164 2334 0692


ε RT ln 1 +1

Ce1113888 1113889 (11)



E 1

(2K)

1113968 (12)






AlndashAl

Al

Al

SiO

O O O

OO O

OOO

OO

O

OO

OO

O

OOO O

O

OOOO

O

OOO

O

OO

O OO

O

O

OO

O

O O

OO

OO

O

O O

O

OO

O

O

OO

O

OO

O

O

OO

Olowast

O

OO

OO

O

OO

O

O

O

O

OO

O

O

O O

OO

OO

O

Si

Si Si

Si

Si

Si Si

Si

SiSi

SiSi

Si

SiSi Si

Si

SiSiSi

Si

Si

Si

Si

SiSi

Si

Si

Si Si Si

Si

Si

Si Si

Si

Si

SiAl

Al

Al

AlAlndash

Alndash

AlndashAlndash

Alndash

Alndash

Alndash

Al

Alndash

Alndash

Alndash

Na+Na+

Na+

Na+

Na+

Na+ Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

MB+

MB+

MB+

MB+

MB+ MB+MB+

MB+MB+

MB+


0

10

20

30

40

Qe (

mg

g)

Ci (mgL)0 5 10 15 20 25 30 35 40 45 50 55 60 65 70







ΔGdeg minusRT lnqe

Ce

Kd qe

Ce


RT

(14)


00

01

02

03

04

05C e

qe

Ce

0 5 10 15 20

(a)

15

20

25

30

35

40

Ln q

e

Ln Ce


(b)

0

5

10

15

20

25

30

35

40

45

q e

Ln Ce


(c)

15

20

25

30

35

40

Ln q

e

e20 10000000 20000000 30000000 40000000 50000000 60000000

(d)










4 Conclusion



Data Availability




References







00029 00030 00031 00032 00033 00034 00035

140

145

150

155

160

165

170

175

180

Ln K

d

1T
























































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls










ndash8

ndash6

ndash4

ndash2

0

2

4

20mgL30mgL40mgL

Ln (q

e ndash q

t)

Time (min)ndash20 0 20 40 60 80 100 120 140 160 180 200

(a)

0

2

4

6

8

10

12

20mgL30mgL40mgL

tqt

Time (min)0 50 100 150 200 250

(b)

ndash2 0 2 4 6 8 10 12 14 16

0

10

20

30

40

20mgL30mgL40mgL

qt

t12

(c)






20 1999 843 0045 0875 2041 0031 0999 6042 1198 068330 2993 721 0046 0866 3030 0028 0999 9309 1778 066940 392 1817 0029 0936 40 00098 0999 1164 2334 0692


ε RT ln 1 +1

Ce1113888 1113889 (11)



E 1

(2K)

1113968 (12)






AlndashAl

Al

Al

SiO

O O O

OO O

OOO

OO

O

OO

OO

O

OOO O

O

OOOO

O

OOO

O

OO

O OO

O

O

OO

O

O O

OO

OO

O

O O

O

OO

O

O

OO

O

OO

O

O

OO

Olowast

O

OO

OO

O

OO

O

O

O

O

OO

O

O

O O

OO

OO

O

Si

Si Si

Si

Si

Si Si

Si

SiSi

SiSi

Si

SiSi Si

Si

SiSiSi

Si

Si

Si

Si

SiSi

Si

Si

Si Si Si

Si

Si

Si Si

Si

Si

SiAl

Al

Al

AlAlndash

Alndash

AlndashAlndash

Alndash

Alndash

Alndash

Al

Alndash

Alndash

Alndash

Na+Na+

Na+

Na+

Na+

Na+ Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

MB+

MB+

MB+

MB+

MB+ MB+MB+

MB+MB+

MB+


0

10

20

30

40

Qe (

mg

g)

Ci (mgL)0 5 10 15 20 25 30 35 40 45 50 55 60 65 70







ΔGdeg minusRT lnqe

Ce

Kd qe

Ce


RT

(14)


00

01

02

03

04

05C e

qe

Ce

0 5 10 15 20

(a)

15

20

25

30

35

40

Ln q

e

Ln Ce


(b)

0

5

10

15

20

25

30

35

40

45

q e

Ln Ce


(c)

15

20

25

30

35

40

Ln q

e

e20 10000000 20000000 30000000 40000000 50000000 60000000

(d)










4 Conclusion



Data Availability




References







00029 00030 00031 00032 00033 00034 00035

140

145

150

155

160

165

170

175

180

Ln K

d

1T
























































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




ε RT ln 1 +1

Ce1113888 1113889 (11)



E 1

(2K)

1113968 (12)






AlndashAl

Al

Al

SiO

O O O

OO O

OOO

OO

O

OO

OO

O

OOO O

O

OOOO

O

OOO

O

OO

O OO

O

O

OO

O

O O

OO

OO

O

O O

O

OO

O

O

OO

O

OO

O

O

OO

Olowast

O

OO

OO

O

OO

O

O

O

O

OO

O

O

O O

OO

OO

O

Si

Si Si

Si

Si

Si Si

Si

SiSi

SiSi

Si

SiSi Si

Si

SiSiSi

Si

Si

Si

Si

SiSi

Si

Si

Si Si Si

Si

Si

Si Si

Si

Si

SiAl

Al

Al

AlAlndash

Alndash

AlndashAlndash

Alndash

Alndash

Alndash

Al

Alndash

Alndash

Alndash

Na+Na+

Na+

Na+

Na+

Na+ Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

MB+

MB+

MB+

MB+

MB+ MB+MB+

MB+MB+

MB+


0

10

20

30

40

Qe (

mg

g)

Ci (mgL)0 5 10 15 20 25 30 35 40 45 50 55 60 65 70







ΔGdeg minusRT lnqe

Ce

Kd qe

Ce


RT

(14)


00

01

02

03

04

05C e

qe

Ce

0 5 10 15 20

(a)

15

20

25

30

35

40

Ln q

e

Ln Ce


(b)

0

5

10

15

20

25

30

35

40

45

q e

Ln Ce


(c)

15

20

25

30

35

40

Ln q

e

e20 10000000 20000000 30000000 40000000 50000000 60000000

(d)










4 Conclusion



Data Availability




References







00029 00030 00031 00032 00033 00034 00035

140

145

150

155

160

165

170

175

180

Ln K

d

1T
























































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls






ΔGdeg minusRT lnqe

Ce

Kd qe

Ce


RT

(14)


00

01

02

03

04

05C e

qe

Ce

0 5 10 15 20

(a)

15

20

25

30

35

40

Ln q

e

Ln Ce


(b)

0

5

10

15

20

25

30

35

40

45

q e

Ln Ce


(c)

15

20

25

30

35

40

Ln q

e

e20 10000000 20000000 30000000 40000000 50000000 60000000

(d)










4 Conclusion



Data Availability




References







00029 00030 00031 00032 00033 00034 00035

140

145

150

155

160

165

170

175

180

Ln K

d

1T
























































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls







4 Conclusion



Data Availability




References







00029 00030 00031 00032 00033 00034 00035

140

145

150

155

160

165

170

175

180

Ln K

d

1T
























































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls






















































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




preparation,characterization,andapplicationof metakaolin ......biochar microparticles [24], silica...

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