Removal of bromophenol blue dye from industrial waste water by synthesizing polymer-clay composite

MOLLIQ-04369; No of Pages 8 Journal of Molecular Liquids xxx (2014) xxx–xxx

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Review

Removal of bromophenol blue dye from industrial waste water by synthesizing polymer-clay composite Adel A. El-Zahhar, Nasser S. Awwad, Emad E. El-Katori ⁎ Department of Chemistry, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudia Arabia

a r t i c l e

i n f o

Article history: Received 22 March 2014 Received in revised form 10 July 2014 Accepted 23 July 2014 Available online xxxx Keywords: Polymer-clay composite Dye adsorption Kinetic and thermodynamic parameters Industrial waste water

a b s t r a c t A composite material was prepared by incorporating the clay (Kaolinite (Kao)) into a poly(acrylamide co-acrylic acid) (P(AAm-AA)) through the in situ polymerization method with cross-linker. The prepared composite adsorbent was firstly characterized by FTIR, SEM, XRD and Thermal analysis. After characterization, the composite adsorbent P(AAm-AA)/Kao was potentially studied for sorption of bromophenol blue (BPB) dye. Different factors that could affect the dye adsorption behavior were studied as time of contact, dye concentration and temperature. The kinetic studies revealed that the adsorption results fitted well with Lagergren (pseudo first order reaction rate). The isotherm studies also display that the adsorption data fit with Freundlisch more than Langmuir isotherm model. Based on the effect of temperature the thermodynamic parameters were calculated and the free energy change (ΔGo) value of −110.323 kJ/mol was obtained, referring to the feasibility and spontaneous nature of the sorption reaction. Also the relatively high negative value of entropy change ΔSo = −509.4 J mol−1 K−1, suggests the chemical nature of the sorption reaction. © 2014 Elsevier B.V. All rights reserved.

Contents 1. 2.

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . Experimental. . . . . . . . . . . . . . . . . . . . . . . . . . 2.1. Materials . . . . . . . . . . . . . . . . . . . . . . . . 2.2. Preparation of composite adsorbent . . . . . . . . . . . . 2.3. Characterization . . . . . . . . . . . . . . . . . . . . . 2.4. Dye adsorption . . . . . . . . . . . . . . . . . . . . . 3. Results and discussion . . . . . . . . . . . . . . . . . . . . . 3.1. Infrared spectra . . . . . . . . . . . . . . . . . . . . . 3.2. Thermal stability . . . . . . . . . . . . . . . . . . . . . 3.3. SEM observations . . . . . . . . . . . . . . . . . . . . 3.4. XRD-analysis . . . . . . . . . . . . . . . . . . . . . . 3.5. Adsorption experiments . . . . . . . . . . . . . . . . . 3.5.1. Kinetic studies . . . . . . . . . . . . . . . . . 3.5.2. Adsorption isotherms . . . . . . . . . . . . . . 3.5.3. Thermodynamic treatment of the adsorption process 4. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1. Introduction

⁎ Corresponding author. Tel.:+966 561365264. E-mail address: [email protected] (E.E. El-Katori).

Organic dyes represent effective chemical hazard encountered in our environment as organic pollutants. These organic pollutants have undesirable effects either on the environment or on human being, so the dye effluent is one of the most serious water pollution source representing

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problems in various industries such as textile, paper, plastic, leather, food, cosmetic, etc. [1,2]. Due to the growing use of dyes, the resulted dye wastewater is becoming a major environmental threat, and the removal of these pollutants from wastewater represents a challenge. Dyes, as many as organic compounds are regularly stable and withstand to go degrade with time, sunlight, biological and chemical treatments. Even small amounts of dyes, when present in wastewater, it can highly affect the aquatic life due to their toxicity and prevention of light penetration [3–5]. The removal of dyes from textile industry wastewater is a major importance, as the presence of dyes in wastewater inhibits the treatment of such water by conventional methods. Although different methods have been developed, the economical issue and effectiveness of the removal method of dyes represent challenge to researchers and technologists. Different methods have been studied for removal of dyes from wastewater, including physical, chemical, and biological methods [1,2,6–8]. Adsorption is one of the most effective methods used for dye removal. Different kinds of adsorbent materials have been reported for dye removal such as activated carbon [9–12], zeolite [9,13,14], fly ash [15,16], chitin and chitosan [17–19]. Polymeric adsorbent materials play an important role in the treatment of wastewater. Polymeric hydrogel materials have attracted more scientific interest due to their many uses and applications in many fields, such as molecular filters, super absorbents, and contact lenses [20–24]. In recent years, the modification of sorption properties of the polymeric adsorbents was potentially studied. Important modification is the incorporation of nano-or micro-particles of inorganic materials, such as montmorillonite, kaolinite, mica, bentonite and sercite into the polymer networks [25–29]. The polymeric composites have found different technological and industrial applications in many fields as; food and pharmaceutical industries, agriculture and related fields (in the controlled release of moisture, fertilizers, pesticides, etc.), electronic instruments (as a protector against corrosion and short circuits, etc.) and biomedicine (as artificial organs, etc.). Chitosan intercalated montmorillonite (Chi-MMT) was prepared and used for adsorption of different dyes [30]. A nanocomposite (NC) material based on nanoclay (Laponite (Lap) XLS) was prepared by incorporating the clay into poly(acrylamide) (PAAm) polymer. The produced composite was used for adsorption of crystal violet dye [31]. In the present study

polymer clay composite was prepared by incorporating the kaolinite clay into poly(acrylamide co-acrylic acid) in presence of crosslinker using chemical polymerization method. The prepared composite (P(AAm-AA)-Kao) was characterized by FTIR, XRD, SEM and thermal analysis and applied for removal of bromophenol blue (BPB) dye from aqueous solutions. 2. Experimental 2.1. Materials Acrylic acid (AA) and acrylamide (AM), were obtained as chemically pure reagents from Shanghai Wulian Chemical Factory, Shanghai, China and were used as received. Potassium persulfate (PPS) as analytical grade was obtained from Xi_an Chemical Reagent Factory, Xi_an, China. N,N-methylenebisacrylamide (MBA) is a chemically pure obtained from Shanghai Chemical Reagent Factory, Shanghai, China, and was used as received. Kaolinite micro-powder was obtained from Xuyi Colloidal Co., Ltd, Jiangsu, China and was used as received. All solutions were prepared with double distilled water. 2.2. Preparation of composite adsorbent Polymer clay composite adsorbent was prepared following a reported procedure [31]. In this procedure, appropriate amount of kaolinite (Fig. 1), crosslinker and initiator was added to acrylic acid with certain degree of neutralization. The produced composite was washed several times with distilled water, dried at 70 °C to constant weight, then milled and screened. All samples were sized to appropriate mesh size. 2.3. Characterization The IR spectrum of the composite adsorbent was recorded on FTIR (KBr method with a NICOLET 6700 FTIR thermo scientific.) using KBr pellets. Thermal stability studies of dry composite and the content of polymer in the composite was determined by thermogravimetric analysis (Shimadzu DTA-50 thermal analyzer), in which the sample was heated from 50 to 900 °C at a heating rate of 10 °C/min. The prepared

Fig. 1. Schematic structure of kaolinite.

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600

Exo

composite was characterized also by X-ray diffractometry (CuKα radiation by Schimadzo X-ray diffraction angle range from 5° to 90° with step of 0.03° and integration time of 4 s per step). Also scanning electron microscope (Philips XL 30 attached with EXD Unit) was used for assigning the surface morphology of the prepared composite.

3

500

400

The bromophenol blue dye was selected as adsorbate. Aqueous dye solution with an initial concentration of 50 mg/L was prepared. In the adsorption experiment, 0.15 g composite adsorbent P(AAm-AA)-Kao was added to each 20 ml of the aqueous dye solution. The mixtures was stirred for 2 h at room temperature and then aged overnight. The dye solution was separated from the adsorbents by centrifugation at 3500 rpm for 10 min. The concentrations of dye in aqueous solution before and after adsorption were measured using UV–visible spectrophotometer (model UV-1800, Japan). The concentrations of dye solutions were determined by linear regression equation, obtained by plotting the calibration curve for dye over a range of concentrations. The amount of dye adsorbed was calculated by subtracting the final concentration from the initial concentration of dye solutions.

ΔQ

2.4. Dye adsorption 300

200

100

0

-100 0

100

200

300

400

500

600

700

800

o

Temperature ( C) Fig. 3. DTA of P(AAm-AA)-Kao composite.

3. Results and discussion 3.3. SEM observations 3.1. Infrared spectra The infrared spectra of composite adsorbent P(AAm-AA)-Kao are shown in Fig. 2. According to the IR spectra the peaks observed were at 3447 cm−1, corresponding to the N–H stretching of acrylamide unit, 2950 cm− 1, corresponding to the C–H stretching of acrylate unite, 1721 cm− 1, corresponding to the υC_O of acrylate unit, 1667 cm− 1, corresponding to the carbonyl moiety of the acrylamide unit, 1175 cm−1, corresponding to the –CO–O– stretching of acrylate unit, 1031 cm−1, corresponding to the Si–O stretching of kaolinite. 3.2. Thermal stability The thermogravimetric analysis (TGA) of P(AAm-AA)-Kao is shown in Fig. 3. The figure displays a very small weight loss at below 100 °C, implying a loss of moisture. While a major weight loss of 70.3% was obtained around 550 °C. The major weight loss started at 505 °C, therefore, it could be inferred that that the introduction of kaolinite to polymer network results in an increase in thermal stability. This finding could be due to the fact that the kaolinite micro-particles in network can act as a heat barrier, which enhances the overall thermal stability of the composite.

The micrographs of P(AAm-AA)-Kao is shown in Fig. 4. The micrograph shows a fine network structure with a microporous appears on the SEM of P(AAm-AA)-Kao, and shows a broad network structure. 3.4. XRD-analysis The XRD-pattern for the composite adsorbent P(AAm-AA)-Kao is shown in Fig. 5. The results in the figure reflect that intercalation of P(AAm-AA) within the clay kaolinite and show also a beak positions shift and beak intensity decrease as well as d-values of ~ 1.36 nm and ~2.25 nm. The broad reflection around 2θ ~ 10–40° was assumed to be due to monolayers of polymer in kaolinite whereas the other different reflection was related to the intercalation bi-layers. 3.5. Adsorption experiments 3.5.1. Kinetic studies The removal of bromophenol blue dye (BPB) on to P(AAm-AA)-Kao was studied with time by varying the equilibrium time (contact time of adsorbent with adsorbate) in the range of 1–60 min. The percentage adsorption of the dye as a function of contact time was plotted in

Fig. 2. Infrared spectrum of the synthesized P(AAm-AM)-Kao.

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A

A

500

Intensity (I)

400

300

200

100

Composite 0

B

0

10

20

30

40

50

60

70

80

90

Two theta 160

B

140

Intensity (I)

120 100 80 60 40 20

Fig. 4. SEM for P(AAm-AA)-Kao composite (A) and dye loaded-P(AAm-AA)Kao (B).

Dye loaded composite

0

Fig. 6, the results in this figure indicate that the equilibrium between the dye and the composite adsorbent was attained within 10 min. The adsorption of dye on composite adsorbent P(AAm-AA)-Kao could involve three consecutive steps. Firstly, the adsorbate species migrate from the bulk liquid phase to the outer surface of adsorbent particles (film diffusion). Secondly, the dye species move within the micro and macropores of adsorbent particles (pore diffusion). Thirdly, the reaction of adsorbate–adsorbent species takes place on the surface. The kinetics of the dye adsorption on composite adsorbent was assayed using the first order rate equation reported by Lagergren [32], Eq. (1) below: logðqe −qt Þ ¼ log qe − k f t=2:303

ð1Þ

where qe and qt are the amount adsorbed of BPB dye per unit mass of adsorbent (mgg−1) at equilibrium and at time t, respectively, kf is the pseudo first order sorption rate constant (min−1). The linear plot of log (qe − qt) v. t in Fig. 7 indicates the applicability of the first-order rate kinetics. The kf value, calculated from the slope of the line in Fig. 7 is 0.230 min−1, which is reported with other constants in Table 1 below. The pseudo-second-order adsorption kinetic rate equation is expressed as: 2

dqt = dt ¼ k2 ðqe−qtÞ

ð2Þ

Where, k2 is the rate constant of pseudo second order adsorption (g mg−1 min−1). For the boundary conditions t = 0 to t = t and qt = 0 to qt = qt the integrated form of Eq. (2) becomes: 1=ðqe – qt Þ ¼ 1=qe þ k2 t

ð3Þ

0

20

40

Two theta

60

80

100

Fig. 5. XRD for P(AAm-AA)-Kao composite, (A) and dye loaded-P(AAm-AA)-Kao, (B).

This is the integrated rate law for a pseudo second order reaction. Eq. (3) can be rearranged to obtain the linear form: t=qt ¼

  2 1=k2 qe þ ðð1=qe Þt

ð4Þ

If the initial adsorption rate (h) (mg g−1 min−1) is: h ¼ k2 qe

2

ð5Þ

Eq. (4) becomes: t = qt ¼ 1 = h þ 1 = qe t

ð6Þ

The plot of (t/qt) and t Fig. 8 should give a linear relationship from which qe and k2 can be determined from the slope and intercept of the plot, respectively. The pseudo-second-order rate constants k2, the calculated h values, and the correlation coefficients (R2) are summarized in Table 1. The Elovich model equation is generally expressed as dqt = dt ¼ α exp ð−βqt Þ

ð7Þ

Where, α is the initial adsorption rate (mg g−1 min−1) and β is the desorption constant (g mg−1) during experiment. The Elovich equation

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A.A. El-Zahhar et al. / Journal of Molecular Liquids xxx (2014) xxx–xxx

100

Table 1 Kinetic parameters for adsorption of BPB dye on P(AAm-AA)-Kao.

80

% Adsorption

5

Model

Parameter

Value

Lagergren (Pseudo first order)

kf (min−1) qe (mg/g) R2 S.D. ks (g mg−1 min−1) h (mg g−1 min−1) R2 S.D. α (g mg−1 min−2) β (mg g−1 min−1) R2 S.D. kid(mg g−1 min−0.5) R2 S.D.

0.230 5.895 0.955 0.394 0.0129 108.225 0.999 0.0150 0.01125 19.297 0.953 5.16 28.546 0.913 8.79

60 Pseudo second order

40 Elovich

20 Intra-particle Diffusion Model

0 0

20

40

60

80

100

Shaking Time (min) Fig. 6. Effect of shaking time on the adsorption of BPB dye by P(AAm-AA)-Kao; dye concentration = 50 mg/l, adsorbent dose 7.5 g/l, Temp. 25 ± 2.

could be simplified by assuming αβ t N N t and applying boundary conditions qt = 0 at t = 0 and qt = qt at t = t Eq. (7) becomes: qt ¼ 1=β ln ðαβÞ þ 1=β ln ðt Þ

ð8Þ

When fitted with Elovich model, the plot of qt vs. ln(t) in Fig. 9 for adsorption of BPB on P(AAm-AA)-Kao should yield a linear relationship with a slope of (1/β) and an intercept of (1/β) ln (αβ). The Elovich model parameters α, β, and correlation coefficient (R2) were calculated and given in Table 1. The intra-particle diffusion model proposed by Weber and Morris [34] based on the following Eq. (9), was applied for the results of adsorption of BPB on P(AAm-AA)-Kao: qt ¼ kid t

ð1=2Þ

þ C

ð9Þ

indicates that the curve is not passing through the origin, so the intraparticle diffusion is not only the rate controlling step . The intraparticle parameters are summarized in Table 1. 3.5.2. Adsorption isotherms The adsorption isotherm for adsorption of BPB dye on to P(AAmAA)-Kao was studied, where aqueous solution containing varied concentrations of BPB dye was applied. Fig. 11 shows the adsorption isotherm of BPB dye adsorption on P(AAm-AA)-Kao. Langmuir adsorption isotherm model was used study the fitting of the experimental results of BPB dye adsorption on P(AAm-AA)-Kao. The Langmuir equation assumes monolayer adsorption of BPB dyes molecules on composite surface and that there is no interaction between the dye molecules. It is then assumed that once a dye molecule occupies a site, no further sorption can take place at that site. Theoretically, there is a surface saturation value is reached, after which no further sorption can occurs. The Langmuir equation is reported as: 1=qe ¼ 1=qo þ 1=qo K L C e

Where kid is the intra-particle diffusion rate constant (mg g−1 min−1/2) and C is a constant. If the rate limiting step is intra-particle diffusion, the graphical representation of (qt) (mg g−1) depending on the square root of the contact time (t1/2) Fig. 10, should yield a straight line passing through the origin [33]. The slope of the plot of qt vs. t1/2 will give the value of the intra-particle diffusion coefficient (kid) and correlation coefficient (R2). The results and the linearity of the graph, indicates the fitness of the obtained results with this model. The intercept value

ð10Þ

Where qe is the adsorbed amount of dye per gram of adsorbent (mg/g), Ce is the equilibrium concentration of dye in solution (mg/g), qo and KL are Langmuir parameters related to maximum monolayer coverage capacity (mg/g) and Langmuir isotherm constant (L/mg), respectively. The values of Langmuir parameters were computed from the slope and intercept of the Langmuir plot of 1/qe vs. 1/Ce given in Fig. 12. The essential features of the Langmuir isotherm could be

1.0 14

0.5 0.0

12

-0.5

t/qt

log(qe-qt)

10 -1.0 -1.5 -2.0

8 6

-2.5 4

-3.0 -3.5

2

-4.0 0

5

10

15

20

25

30

35

40

45

50

55

60

Time (min) Fig. 7. Lagargern plot for adsorption of BPB dye by P(AAm-AA)-Kao); dye concentration = 50 mg/l, adsorbent dose 7.5 g/l, Temp. 25 ± 2.

0

10

20

30

40

50

60

70

80

90

100

Time (min) Fig. 8. Pseudo second order sorption rate plot for sorption of BPB dye by (AAm-AA)-Kao); dye concentration = 50 mg/l, adsorbent dose 7.5 g/l, Temp. 25 ± 2.

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100

8 7

80

qe(mg/g)

qt(mg/g)

6 60

5 4

40 3 2

20

1 0 0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0

5.0

2

4

6

8

10

12

14

Ce(mg/L)

ln(Time) Fig. 9. Elovich plot for sorption of BPB dye on P(AAm-AA)-Kao); dye concentration = 50 mg/l, adsorbent dose 7.5 g/l, Temp. 25 ± 2oC.

Fig. 11. Sorption isotherm for BPB dye and P(AAm-AA)-Kao time 60 min, adsorbent dose 7.5 g/l.

expressed in terms of equilibrium parameter RL, which is a dimensionless constant referred to as separation factor or equilibrium parameter [34].

dye in solution(mg/L), Kf = Freundlich isotherm constant (mg/g) and n = adsorption intensity. The constant Kf is related to adsorption capacity, while 1/n is a related to adsorption intensity [36]. The values of Kf and n were calculated from the plot of logqe vs. logCe Fig. 13. When n = 1, the distribution of adsorbate between the two phases are independent of the concentration. If n lies between one and ten, this indicates a favorable sorption process [37]. The calculated Freundlich parameters indicate that the value of 1/n = 0.347 while n = 2.881 indicating that the sorption of BPB dye on P(AAm-AA)-Kao is favorable and the R2 value is 0.989. Comparing the Langmuir isotherm model with the Freundlich isotherm model reflects the applicability of Freundlich model, which is better suited for characterizing multi-layer adsorption process.

RL ¼ 1=ð1 þ K L C o Þ

ð11Þ

Where: Co = initial concentration, KL = the Langmuir constant related to the energy of adsorption. RL value indicates the adsorption nature to be either unfavorable if RL N 1, linear if RL = 1, favorable if 0 b RL b 1 and irreversible if RL = 0. From the data calculated in Table 2, the RL is greater than 0 but less than 1 indicating that adsorption reaction is favorable with respect to Langmuir isotherm model. The maximum monolayer coverage capacity (Qo) from Langmuir Isotherm model was determined to be 10.78 mg/g, KL (Langmuir isotherm constant) is 2.873 L/mg, RL (the separation factor) is 0.103 indicating that the equilibrium sorption was favorable and the R2 value is 0.981 proving that the sorption data fitted to Langmuir Isotherm model. Freundlich Adsorption Isotherm is commonly used to describe the adsorption characteristics for the heterogeneous surface [35]. The linear form of Freundlich equation is expressed as: logqe ¼ logK f – 1=n logC e

ð12Þ

Where qe is the amount of dye adsorbed per gram of the adsorbent at equilibrium (mg/g), Ce is the equilibrium concentration of

3.5.3. Thermodynamic treatment of the adsorption process The adsorption of BPB dye on P(AAm-AA)-Kao was studied as a function experiment temperature within the temperature range of 295– 323K. An increase in temperature resulted in increase in the amount of BPB dye adsorbed per unit mass of sorbents showing an endothermic nature of the sorption reaction. This may be due to the fact that the network of cross-linked polymer with clay platelets goes loose, homogeneous, and changeable at higher temperature. This increases the adsorbent surfaces available for dye adsorption with increasing temperature. Therefore, thermodynamic parameters were evaluated to assess the thermodynamic feasibility and to confirm the nature of the sorption 1.0

100

0.9 0.8

80

1/qe(g/mg)

qt/mg/g

0.7 60

40

0.6 0.5 0.4 0.3 0.2

20

0.1 0.0

0 2

4

6

8

10

(t)1/2 Fig. 10. Intraparticle diffusion plot for sorption of BPB dye on P(AAm-AA)-Kao); dye concentration = 50 mg/l, adsorbent dose 7.5 g/l, Temp. 25 ± 2oC.

0

2

4

6

8

10

12

1/Ce(L/mg) Fig. 12. Langmuir plot for sorption of BPB dye on P(AAm-AA)-Kao time 60 min, adsorbent dose 7.5 g/l.

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9.0

Table 2 Thermodynamic parameters for sorption of BPB dye on P(AAm-AA)-Kao.

8.8

Thermodynamic parameters ΔH° (kJ mol−1)

295 303 313 323

110.323

8.6

−ΔG°(kJ mol−1)

−ΔSo (J mol−1 K−1)

40.04 43.39 48.36 54.32

509.70 507.30 507.07 509.73

8.4 8.2

lnkd

Temperature K

7

8.0 7.8

process. The thermodynamic parameters corresponding to BPB dye sorption on composite adsorbent were assessed using Van't Hoff equation [38]: o

o

log kd ¼ ΔS =2:303R – ΔH =2:303RT

ð13Þ

Where kd is the distribution coefficient of dye and equals to (qe/Ce), ΔS° is the entropy change (J mol−1 K−1), R is the ideal gas constant (8.314 J mol−1 K− 1) and T is the absolute temperature in Kelvin. A plot of logkd v. 1/T was constructed and shown in Fig. 14, the figure shows straight line with slope equal to the value of apparent enthalpy (ΔH°) for the overall system. The values of other thermodynamic parameters were calculated at different temperatures, sing the following equations, and listed in Table 2. o

ΔG ¼ −2:303 RT ln kd

o

o

ð14Þ

o

ΔG ¼ ΔH −T ΔS

ð15Þ

The negative ΔG° values confirm the spontaneous nature and feasibility of the sorption process of dye on P(AAm-AA)-Kao. With increasing temperature, the ΔG° value increased from 40.04 to 54.32 kJ mol−1. This indicates that favorable dye adsorption takes place with increasing temperature. The positive ΔH° value indicates the endothermic nature of BPB dye sorption onto the composite adsorbent. The relatively great negative ΔS° values suggest the decrease in adsorbate concentration in solid–solution interface indicating thereby the increase in adsorbate concentration onto the solid phase. This finding is the normal consequence of the chemical sorption phenomenon, which suggests the chemical nature of the sorption of BPB dye on the polymer clay composite adsorbent [39]. Also, the negative values of ΔS° specified an increased randomness at the composite/solution interface during the progress of sorption process. 1.0 0.9 0.8 0.7

logqe

0.6 0.5 0.4 0.3 0.2 0.1 0.0 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

logCe Fig. 13. Freundlich plot for sorption BPB dye on P(AAm-AA)-Kao time 60 min, adsorbent dose 7.5 g/l.

7.6 7.4 7.2 7.0 0.0030

0.0031

0.0032

0.0033

0.0034

1/T (K-1) Fig. 14. Van't Hoff plots for sorption of BPB dye on P(AAm-AA)-Kao.

4. Conclusion Polymer clay composite adsorbent material based on kaolinite clay and crosslinked polyacrylamide co-acrylic was prepared successfully by incorporating kaolinite clay into a P(AAm-AA) through in situ polymerization with cross-linker. The SEM image and XRD display the intercalation of polymer with clay. The removal efficiency of the composite material was assayed for adsorption of water-soluble dye BPB by studying the adsorption kinetics of BPB dye. The rate constants and kinetic parameters according to different kinetic models were evaluated. The thermodynamic parameters revealed the feasibility and spontaneous nature of the sorption reaction. Also the isotherm studies suggested that the chemical nature is the major one responsible for the sorption reaction. The study revealed that the prepared polymer clay composite could be potentially used as BPB dye removal from aqueous solutions.

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