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Chemical Engineering Journal 181– 182 (2012) 343– 351

Contents lists available at SciVerse ScienceDirect

Chemical Engineering Journal

j ourna l ho mepage: www.elsev ier .com/ locate /ce j

uinoline adsorption onto granular activated carbon and bagasse fly ash

. Rameshrajaa, Vimal Chandra Srivastavaa, Jai Prakash Kushwahab, Indra Deo Malla,∗

Department of Chemical Engineering, Indian Institute of Technology, Roorkee, Roorkee 247667, Uttarakhand, IndiaDepartment of Chemical Engineering, Thapar University, Patiala, Punjab, India

r t i c l e i n f o

rticle history:eceived 5 August 2011eceived in revised form2 November 2011ccepted 23 November 2011

a b s t r a c t

Adsorption of quinoline onto granular activated carbon (GAC) and bagasse fly ash (BFA) were studiedin a batch system. Various parameters such as pH, adsorbent dose (m), temperature (T), initial quino-line concentration (Co) and contact time (t) were optimised. Equilibrium contact time and optimum pHwere found to be 8 h and 5.5, respectively, for both the adsorbents. The adsorbent dose for GAC andBFA were found to be of 5 g/l and 10 g/l, respectively. Pseudo-second-order kinetic model was found to

eywords:uinolineranular activated carbonagasse fly ashdsorption kinetics

sotherms

fit the adsorption kinetic data. Redlich and Peterson (R–P) isotherm generally fitted the experimentaldata for quinoline adsorption onto GAC and BFA. The adsorption of quinoline onto GAC and BFA wasfound to be endothermic. Changes in entropy and heat of adsorption for adsorption of quinoline on GACwere determined as 112.96 kJ/mol K and 12.64 kJ/mol, respectively, whereas for BFA was determined as77.78 kJ/mol K and 6.86 kJ/mol, respectively.

© 2011 Elsevier B.V. All rights reserved.

. Introduction

Quinoline is found to occur widely in petroleum refining andoal processing effluents and as well as in the shale oil [1–4].t is given out as an intermediate in the production of com-ounds such as 8-hydroxyquinoline, hydroxyquinoline sulphatend copper-8-hydroxyquinoline. It is also used as a catalyst inetallurgical industries and in the production of dyes, polymers

nd agricultural chemicals. It is also used as solvent for resins anderpenes [5,6]. Coal tar and petroleum refining is the major con-ributor to the world quinoline production which is greater than000 tonne/year [2]. The approximate contents of nitrogen contain-

ng hetero-aromatic compounds in high-temperature coal tar are.9% carbazole, 0.2–0.3% quinoline, 0.2% indole, 0.1–0.2% isoquino-

ine, 0.1–0.2% 2-methylquinoline, 0.1% acridine, 0.03% pyridine, and.02% 2-methylpyridine [7,8].

Quinoline is a hygroscopic liquid with strong odour. Manytudies have shown that the quinoline and its derivatives haveoxic, carcinogenic and mutagenic activity to animals and humans.ischarging quinoline containing wastes does great damage touman health and environmental quality. Various treatment meth-

ds such as physico-chemical and biological methods can be usedor the treatment of quinoline containing wastewaters. Adsorp-ive treatment has been found attractive for the removal of organic

∗ Corresponding author. Tel.: +91 133 228 5319; fax: +91 133 227 6535.E-mail addresses: vimalcsr@yahoo.co.in (V.C. Srivastava), jps kag@yahoo.co.in

J.P. Kushwaha), id mall2000@yahoo.co.in (I.D. Mall).

385-8947/$ – see front matter © 2011 Elsevier B.V. All rights reserved.oi:10.1016/j.cej.2011.11.090

compounds from wastewaters. Few studies have been reported forthe adsorptive removal of quinoline (Table 1). Various adsorbentssuch as rundle spent shale [9], silica gel [10], combusted rundlespent shale [11], kaolinite and montmorillonite [12], fibrous sili-cates and patagonian saponite [13], estuarine sediment [14], Pt, Pdand Rh [15] and mesoporous molecular sieve Ti-HMS [16] wereused (Table 1). However, available studies did not cover the effectof temperature, controlling mechanism of the sorption process,kinetic and thermodynamic aspects for adsorption of quinoline.

Bagasse fly ash (BFA) is a waste collected from the particulatecollection equipment attached upstream to the stacks of bagasse-fired boilers. It is mainly used for land filling, and partly used as fillerin building materials and paper and wood boards. BFA has goodadsorptive properties and has been used for the removal of CODand colour from dairy mill wastewater [17] and paper mill effluents[18]. Various researchers have utilised it for the adsorptive removalof phenolic compounds [19,20], dyes [21] and metals [22,23].

This paper deals with the adsorption of quinoline from aque-ous solution onto granular activated carbon (GAC) and BFA. Theeffect of initial pH (pHo) of the quinoline solution (2 ≤ pHo ≤ 12),adsorbent dose (m) (1 ≤ m ≤ 30 g/l), contact time (t) (0 ≤ t ≤ 24 h),initial quinoline concentration (50 ≤ Co ≤ 1000 mg/l) and tempera-ture (T) (288 ≤ T ≤ 318 K) on the sorption of quinoline onto GAC andBFA have been investigated. Sorption kinetics and equilibrium char-acteristics have also been studied. Various equilibrium isotherms

(two and three parameters) such as Langmuir, Freundlich, Temkinand Redlich–Peterson (R–P) isotherms have been tested for theirapplicability to represent the experimental sorption data and var-ious isotherm parameters were also calculated. Thermodynamic

344 D. Rameshraja et al. / Chemical Engineering Journal 181– 182 (2012) 343– 351

Table 1Adsorption of quinoline by various adsorbents.

Adsorbate Adsorbent Solvent Optimum conditions Reference

Quinoline and Pyridine Rundle spent shale Water pH 8 [9]Quinoline, m-cresol and 1-naphthol Silica gel n-Hexane Temperature = 30 ◦C, concentration range = 1–30 mol/m3 [10]Quinoline Combusted rundle spent shale Water pH 8, temperature = 25 ◦C [11]Quinoline Kaolinite and montmorillonite Water pH 3.5–4 for kaolinite and pH 3.5–5 for montmorillonite [12]

Wa

Wa

so

2

2

TTtomsc1mtp

2

(tcSr4(atu

wi(a

2

kwpts(t1wr

Quinoline Sepiolite, palygorskite, saponite

Naphthalene and quinoline Pt, Pd and Rh

Pyridine, quinoline, pyrrole and indole Mesoporous molecular sieve Ti-HMS

tudy has also been made to understand the effect of temperaturen the quinoline sorption.

. Materials and methods

.1. Adsorbent and adsorbate

Commercial grade coconut-based GAC was purchased from Zeoech Adsorbents Pvt. Ltd, New Delhi, India. BFA was obtained fromriveni sugar mill, Deoband, UP, India. It was collected from the par-iculate collection device and was used without any pre-treatmentther than sieving. The BET surface area of GAC and BFA was esti-ated by the standard adsorption of N2 at 77.15 K. Quinoline was

upplied by Ranbaxy Fine Chemicals, New Delhi, India. All thehemicals used in this study were of analytical reagent (AR) grade.

g/l quinoline stock solution was prepared by mixing an accuratelyeasured volume of aqueous quinoline solution with double dis-

illed water (DDW) for the experiments. The test solutions wererepared by diluting the stock solution in DDW.

.2. Instrumentation

X-ray diffraction (XRD) analysis was carried out by using PhillipsHolland) diffraction unit (Model PW1140/90) with copper as thearget and nickel as the filter media. Radiation was maintainedonstant at 1.542 A. Goniometric speed was maintained at 1◦/min.canning electron microscope analysis of GAC and BFA was car-ied out before and after the adsorption of quinoline by using LEO35 VP Scanning electron microscope. Fourier Transform InfraredFTIR) spectra were obtained over a range of 4000–400 cm−1 with

Nicolet Avatar 370 CsI spectrometer (Thermo Electrom Corpora-ion, USA) using KBr pellet technique. MAC bulk density meter wassed to measure bulk density of GAC and BFA.

Initial quinoline and residual concentrations after adsorptionere determined by finding out the absorbance at the character-

stic wavelength using a double beam UV–vis spectrophotometerHACH, DR 5000, USA). The wavelength corresponding to maximumbsorbance (�max) was found to be 280 nm.

.3. Batch adsorption study

For each of batch experiments, 100 ml of quinoline solution ofnown concentration was taken in a 250 ml stoppered conical flaskith a known amount of GAC (g/l) and BFA (g/l) and the initialH of the solutions were adjusted using H2SO4 and NaOH solu-ions. The mixture was agitated in a temperature controlled orbitalhaker with a constant speed of 150 rpm at a specific temperaturelike 15 ◦C, 30 ◦C and 45 ◦C). The samples were withdrawn and cen-

rifuged using a centrifuge (Remi Instruments, Mumbai, India) at0,000 rpm for 5 min. The supernatant solutions after centrifugedere analysed using UV–vis spectrophotometer which gives the

esidual concentration of quinoline.

ter pH 8.38, 9.1 and ∼3 [13][15]

ter Temperature = 20 ◦C, contact time ≥45 min [16]

The percentage removal of quinoline was calculated using thefollowing relation:

Percent removal = (C0 − Ce)100C0

(1)

Similarly for the equilibrium adsorption uptake, qe (mg/g) werecalculated as:

qe = (C0 − Ce)w

V (2)

where Ce is the equilibrium adsorbate concentration, V is the vol-ume of the adsorbate (l) and w is the mass of adsorbent (g).

2.4. Desorption study

Batch desorption study was carried out using two differentmethods, solvent desorption and thermal desorption, as describedby Rauthula and Srivastava [24] and Suresh et al. [25]. For desorp-tion study, quinoline-loaded GAC was separated from the adsorbatesolution. Solvent desorption study was carried out by agitating sep-arated quinoline-loaded GAC (4 g/l) with 50 ml of aqueous solutionof HCl, H2SO4, HNO3, distilled water, CH3COOH, C2H5OH, acetoneand NaOH of known concentration or water at 303 K with a speed of150 rpm for 24 h in the orbital shaker. Same procedure was followedfor desorption study of quinoline-loaded BFA.

In the thermal desorption study, separated quinoline-loadedGAC was dried for 2 h in an oven at 373 K, thereafter, it was keptin furnace for 3 h at 623 K. After 3 h, samples were taken outfrom the furnace and kept in the desicator. The unloaded GACand BFA were again used for adsorption of quinoline; and thisadsorption–desorption exercise was repeated five times.

3. Results and discussions

3.1. Characterisation of adsorbent

The average particle size of GAC and BFA were measured to be2671 and 547 �m, respectively. The BET pore surface area of GACand BFA were found to be 174 m2/g and 156.9 m2/g, respectively.The bulk density of GAC was determined as 506.7 kg/m3 whereasfor BFA it was 133.3 kg/m3. The XRD spectra of blank and loadedGAC and BFA are shown in Fig. 1. XRD spectra of GAC shows thepresence of Moganite (SiO2), Akdalaite [(Al2O3)4·H2O], Tamarugite[NaAl(SO4)2·6H2O] and Fersilicate (FeSi) as major components;and quinoline also gets loaded in the form of Ammonioleucite(NH4,K)AlSi2O6 and Siderazot (Fe5N2) in both the adsorbents. Sil-ica (SiO2), Wollastonite (CaSiO3), Aragonite (CaCO3) and Akdalaite((Al2O3)4.H2O) were the major components in BFA. The broaderpeak in the XRD spectra of both GAC and BFA show the presence ofamorphous form of silica. XRD of the GAC did not show presence ofany carbon. It is because XRD shows peaks due to crystalline mate-

rials only. Suresh et al. [26] also did not observe any peak of carbonin GAC.

The morphologies of GAC and BFA were examined under scan-ning electron microscope (SEM). The SEMs of GAC and BFA are

D. Rameshraja et al. / Chemical Engineerin

saoa

3

wt

A(ta5cc

mAailq

Fig. 1. XRD spectra of blank and quinoline loaded (a) GAC and (b) BFA.

hown in Fig. 2. The BFA has linear type of fibres with pores in itnd at other places and has skeletal structure. Further the numberf pores in BFA are found to be less than that of GAC and these arelso relatively larger in size in BFA.

.2. Effect of solution initial pH (pHo) and adsorbents dosage (m)

Intake of quinoline was examined as a function of pHo (2–12)ith Co = 100 mg/l, m = 5 g/l for GAC and 10 g/l for BFA, T = 303 K and

= 24 h. Results are shown in Fig. 3.The removal efficiency increased with an increase in pHo upto 5.

n increase in pHo from 5 to 12 did not affect the removal efficiency96% for GAC and 84% for BFA) much (Fig. 3). Fig. 3 also shows thathere is increase in final pH (pHf) of the quinoline solution afterdsorption of quinoline onto BFA. As pHo was increased from 2 to, pHf increased from 2.5 to 9.5. For pHo ≥ 5, pHf becomes nearlyonstant at 9.5. But, for intake of quinoline on GAC, pHf is nearlyonstant to pHo.

At lower pHo ≈2, the H+ ion concentration was very high whichay be limiting the adsorption of quinoline onto GAC and BFA.n increase in pHo reduces the H+ ion concentration and hence,

dsorption of quinoline onto GAC and BFA increases. The increasen pH may due to the adsorption of H+ ions onto BFA. It seems that atower concentration H+ ions present in the solution compete withuinoline adsorption onto the adsorbents.

g Journal 181– 182 (2012) 343– 351 345

The GAC showed better quinoline removal efficiency when com-pared with BFA as adsorbent. Higher adsorption capacity of GAC ascompared to BFA may be due to higher surface area of GAC. It mayalso be due to greater affinity of quinoline to GAC and lower com-petitive adsorption of H+ ions onto GAC as shown by lower increasein pHo in case of GAC.

The natural pH value of quinoline solution without any pHadjustment by HCl or NaOH was approximately 5.5 in this study.Therefore, pHo 5.5 was selected as optimum pH for further exper-iments. This pHo was maintained constant by use of appropriatebuffer in further studies.

The FTIR spectra of blank and quinoline loaded GAC and BFAat natural pH is shown in Fig. 4. Peak at ∼770 cm−1 indicates thepresence of SiH. The bands existed in the range of ∼1355 cm−1

in both the adsorbents is attributed to the weak methyl group.Presence of CO group stretching from aldehydes and ketones isindicated by a broad peak in the region of 1500–1700 cm−1 withpeak at 1595 cm−1. This may also be due to conjugated hydrocar-bon bonded carbonyl groups. Thus, FTIR of GAC is similar to BFA asthey have similar functional groups on their surface. FTIRs of theadsorbents after quinoline adsorption are also similar. Quinolineloaded GAC and BFA FTIR spectra show either shifting or changethe peak height in the FTIRs of the respective adsorbents indicatingthat the functional groups at these wave numbers participate in thequinoline adsorption. The difference in intensity of peaks betweenblank adsorbent and quinoline loaded adsorbent is higher for GACas compared to that for BFA. This may be due to higher amount ofquinoline adsorption onto GAC.

The effect of m value on the amount of quinoline adsorbed wasalso studied. For this, m value was varied from 1 to 30 g/l, whileCo was 100 mg/l, T = 303, pHo 5.5 and t = 24 h. As the m value wasincreased, the intake of quinoline onto GAC and BFA first increasedrapidly then became constant (Fig. 5). For GAC, intake of quino-line was found to be 93.5% at m = 5 g/l, beyond which the removalincreased only slightly and attained a steady removal of 98.2%.An increase in m value for GAC from 5 to 10 g/l increased quino-line intake by 4.7% only. Therefore, considering the cost of GAC,optimum m (mopt) for GAC was found to be 5 g/l. For quinolineadsorption onto BFA, percent removal was constant for BFA dosage(m) in the range of 10–30 g/l. This may be due to the fact that form > 10 g/l, agglomeration of BFA particles did not allow the remain-ing quinoline molecules to access the vacant adsorption sites onBFA. For BFA, optimum m (mopt) was found to be 10 g/l giving 82% ofquinoline removal. Therefore, m values of 5 g/l for GAC and 10 g/l forBFA were chosen as the mopt value for further studies on adsorptionof quinoline.

3.3. Effect of contact time and kinetics of adsorption

Fig. 6 shows the effect of contact time (by data points) onadsorptive quinoline removal by GAC and BFA. For this, solutionof quinoline having Co = 50–1000 mg/l and pHo 5.5, were kept incontact with the GAC (mopt = 5 g/l) and BFA (mopt = 10 g/l) for 24 hat T = 303 K.

Quinoline intake increases with t and attains equilibrium atabout t = 4 h for low concentration of quinoline and 10 h for highconcentration of quinoline for both the adsorbents. Rapid uptakeof quinoline on the sorbent can be seen within the first 30 min ofadsorption due to availability of larger vacant surface for adsorp-tion during the initial stage of adsorption process (Fig. 6). The initialrapid uptake indicates surface bound sorption and the slow secondphase due to long range diffusion of adsorbate onto the interior

pores of the adsorbents [27]. It is clear from Fig. 6 that the rate ofuptake is limited by the Co. The increase in Co adds to the interac-tion between quinoline and the adsorbent. The rate of intake alsoincreases with the increase in Co due to increase in the driving force.

346 D. Rameshraja et al. / Chemical Engineering Journal 181– 182 (2012) 343– 351

Fig. 2. SEM of blank (a) GAC, (c) BFA and q

0

2

4

6

8

10

12

14

0

20

40

60

80

100

0 2 4 6 8 10 12 14

pHf

Perc

ent R

emov

al

pHo

GACBFAGAC pHfBFA pHf

Fig. 3. Effect of initial pHo on the removal of quinoline by GAC and BFA(Co = 100 mg/l, m = 5 g/l for GAC and 10 g/l for BFA, T = 303 K, t = 24 h).

uinoline loaded (b) GAC and (d) BFA.

Also, the rate of uptake is limited by solution components affinityto the adsorbent, diffusion coefficient of the adsorbate in the bulkand solid phases, the pore size distribution of the adsorbent, andthe degree of mixing [28].

Quinoline adsorption on GAC and BFA at any instant (t) was stud-ied by pseudo-first-order model and pseudo-second-order model.

Pseudo-first-order model is given as [29,30]:

qt = qe [1 − exp (−kft)] (3)

where qt is amount of quinoline adsorbed (mg/g) at time (t) (min)and kf is the rate constant of pseudo first-order adsorption (min−1).

Pseudo-second-order model is represented as [31,32]:

qt = tksq2e

1 + tksqe(4)

The initial adsorption rate, h (mg/g min), at t → 0 is defined as:

h = ksq2e (5)

where ks is the rate constant of pseudo second-order adsorption(g/mg min).

These two kinetic models have been used to test their valid-ity with the kinetic experimental adsorption data using non-linear

D. Rameshraja et al. / Chemical Engineering Journal 181– 182 (2012) 343– 351 347

nd qu

rfm

hfMfitkoq

3

iiha

Fig. 4. FTIR spectra of blank a

egression. Marquardt’s percent standard deviation (MPSD) errorunction [33] was employed to find out the most suitable kinetic

odel to represent the experimental data.Table 2 shows the best fit values of kinetic parameters such as kf,

, qe and ks along with the correlation coefficients and MPSD valuesor both pseudo-first order and pseudo second order models. The

PSD and R2 values show that the pseudo-second-order model bestts adsorption kinetic data for both the adsorbents. It may be seenhat the h and qe values increase with an increase in Co, whereas,s decreases with an increase in Co. Fig. 6a and b shows fittingsf pseudo-second order-model by solid lines for the removal ofuinoline by GAC and BFA, respectively.

.4. Adsorption controlling mechanism

Intraparticle diffusion may possibly be the rate controlling dur-

ng adsorption of quinoline on GAC and BFA. Adsorption processs controlled by the intraparticle diffusion in well-mixed solutionsaving high concentration of adsorbate and larger particle sizes ofdsorbents [34].

inoline loaded GAC and BFA.

Intraparticle diffusion model was proposed by Weber and Mor-ris [35], which is expressed by following equation:

qt = kidt1/2 + I (6)

where kid is the intraparticle diffusion rate constant (mg/g min1/2)and I is the intercept, which represents the thickness of the bound-ary layer. A larger intercept means thicker boundary layer [36].

Plot of qt vs. t1/2 should be linear if intraparticle diffusion isinvolved in the adsorption processes, and if these lines pass throughthe origin, intraparticle diffusion is the rate-controlling step [37].However, two or more steps may influence the adsorption processif the data exhibit multi-linear plots.

Fig. 7 shows plot of qt vs. t1/2 for adsorption of quinoline ontoGAC and BFA. This figure shows two linear plots. Therefore, morethan one process is controlling the adsorption process. First portionshows the slow adsorption of quinoline and that the intraparticle

diffusion is rate-limiting. Extremely low adsorbate concentrationsleft in the solution, slows down the intraparticle diffusion, which isfinal equilibrium stage of adsorption and shown by second linearportion [38]. Kid,1 and Kid,2 are the slopes of the linear portions

348 D. Rameshraja et al. / Chemical Engineerin

Fig. 5. Effect of adsorbent dosage on the removal of quinoline by GAC and BFA(Co = 100 mg/l, pHo 5.5, T = 303 K, t = 24 h).

0

20

40

60

80

100

0 500 1000 15 00

q t(m

g/g)

Time (min)

50 10 0 250 500 100 0

Co (mg/l ))a(

Fig. 6. Effect of contact time and initial concentration on the adsorption of quinoline bypredicted by the pseudo-second-order model. mopt = 5 g/l of GAC, mopt = 10 g/l of BFA, T = 3

Table 2Kinetic parameters for the removal of quinoline by GAC and BFA (t = 24 h, Co = 50–1000 m

Quinoline-GAC system

50 mg/l 100 mg/l 250 mg/l 500 mg/l 1000

Pseudo 1st orderkf (min−1) 0.012 0.010 0.008 0.018 0.0qe, exp(mg/g) 8.78 18.97 46.88 67.33 77.8qe, cal (mg/g) 8.58 18.97 46.88 67.33 77.8R2 (non-linear) 0.998 0.997 0.988 0.979 0.9MPSD 19.95 29.17 48.45 32.77 28.2Pseudo 2nd orderks (g/mg min) 0.001 0.001 0.0002 0.0003 0.0h (mg/g min) 0.12 0.25 0.60 1.48 1.8qe, cal (mg/g) 9.44 20.63 50.50 69.98 80.5R2 (non-linear) 0.994 0.997 0.990 0.998 0.9MPSD 32.27 35.28 37.60 10.28 11.3

Weber Morriskid1 (mg/g min1/2) 0.461 0.847 1.967 1.997 2.5I1 0.26 2.28 3.57 22.70 26.1R2 0.905 0.936 0.989 0.909 0.9Kid2 (mg/g min1/2) 0.025 0.029 0.067 0.238 0.2I2 7.88 17.98 44.55 59.54 71.4R2 0.850 0.407 0.407 0.458 0.3

g Journal 181– 182 (2012) 343– 351

and their values are increasing with Co. This is due to increase indriving force with Co and adsorption through meso- and micro-pores. Also, these lines do not pass through the origin. Therefore,surface adsorption and intra-particle transport within the pores ofGAC and BFA controls the adsorption process.

3.5. Adsorption isotherm modelling

Adsorption capacity of GAC and BFA for quinoline was also foundto increase with an increase in temperature from 15 to 45 ◦C forCo = 10–1000 mg/l, m = 5 g/l for GAC and 10 g/l for BFA, t = 24 h andpHo 5.5(Fig. 8). Therefore, quinoline adsorption on GAC and BFAis endothermic in nature. The extent of adsorption increased withan increase temperature so the sorption of quinoline by both GACand BFA may involve not only physical adsorption but also chemicaladsorption. Enhanced adsorptive capacity of GAC and BFA at highertemperature may be due to activation of the adsorbent surface ormaking of some new active sites on the adsorbent surface. Thiscould be due to the fact that an increase in temperature enhances

mobility of quinoline from the bulk to the adsorbent surface anddegree of penetration within GAC and BFA structure overcomingthe activation energy barrier and enhancing the rate of intraparticlediffusion [17,39].

0

10

20

30

40

50

0 500 1000 150 0

q t(m

g/g)

Time (min)

50 100 250 50 0 100 0

Co (mg/l))b(

(a) GAC and (b) BFA. Experimental data points given by the symbols and the lines03 K, pHo 5.5.

g/l, m = 5 g/l for GAC and m = 10 g/l for BFA, T = 303 K).

Quinoline-BFA system

mg/l 50 mg/l 100 mg/l 250 mg/l 500 mg/l 1000 mg/l

15 0.009 0.008 0.010 0.011 0.0092 5.07 9.15 18.35 25.99 32.671 5.05 9.15 17.80 25.47 32.3283 0.991 0.995 0.979 0.976 0.9881 38.87 28.75 45.92 40.84 32.79

003 0.002 0.001 0.001 0.0004 0.00035 0.07 0.08 0.20 0.31 0.372 5.42 10.20 19.69 27.94 35.3697 0.995 0.999 0.996 0.996 0.9971 44.33 6.64 22.04 19.31 20.83

51 0.250 0.382 0.501 0.874 1.0732 0.27 0.35 4.84 4.68 7.4927 0.906 0.973 0.934 0.968 0.93000 0.032 0.036 0.098 0.179 0.0511 3.97 7.88 14.89 19.87 30.8392 0.912 0.835 0.760 0.759 0.885

D. Rameshraja et al. / Chemical Engineering Journal 181– 182 (2012) 343– 351 349

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40

(a) (b)

q t(m

g/g)

Time0.5 (min0.5)

501002505001000

Co (mg/l )

0

5

10

15

20

25

30

35

0 10 20 30 40

q t(m

g/g)

Time0.5 (min0.5)

501002505001000

Co (mg/l)

F = 24 hr

tcdaadiTur

FGeFbe

fBhe

Fl

ig. 7. Weber–Morris plot for the treatment of quinoline by (a) GAC and (b) BFA. tespectively.

To optimize the design of adsorption system for the adsorp-ion of adsorbate, it is necessary to establish the most appropriateorrelation for the equilibrium curves. The adsorption isothermescribes the relationship between the amount of adsorbatedsorbed on the adsorbent and the concentration of dissolveddsorbate in the liquid at equilibrium. Srivastava et al. [40] haveiscussed the theory associated with the most commonly used

sotherm models. Well-known Langmuir [41], Freundlich [42],emkin [43] and Redlich and Peterson (R–P) [44] isotherms weresed to fit the isothermal experimental data using non-linearegression fit.

The various R2 values and various parameters for the Langmuir,reundlich, Tempkin and R–P isotherms are shown in Table 3. ForAC, comparing R2 values, it is clear that R–P isotherm best fits thexperimental data at higher temperature but at lower temperaturesreundlich isotherm best fits the data. While for BFA, R–P isothermest fits the experimental data at all temperatures. The fitting ofxperimental data is shown in Fig. 8.

The qm values estimated from the Langmuir model increased

rom 160.03 to 174.72 mg/g for GAC and 31.18 to 45.84 mg/g forFA as temperature increased from 15 to 45 ◦C. Therefore, GAC hasigher affinity than BFA for quinoline. Also, the KF value is consid-red an indicator of the adsorption capacity of GAC and BFA. The KF

0

20

40

60

80

100

120

140

160

0 100 200 300

qe (m

g/g)

Ce (mg/l)

(a) (

288 K

303 K

318 K

ig. 8. Equilibrium adsorption isotherms at different temperature for the treatment of quines predicated by R–P isotherm model. t = 24 h, Co = 10–1000 mg/l, m = 5 g/l for GAC, m =

, Co = 50, 100, 250, 500 and 1000 mg/l, mopt = 5 g/l for GAC and mopt = 10 g/l for BFA

value is higher at higher temperature for both the adsorbents indi-cating endothermic nature of adsorption. At 45 ◦C, GAC has higheradsorption capacity than BFA. The values of 1/n in for Freundlichisotherm were found to be less than 1 for both the adsorbents whichindicates that the adsorption is favourable.

3.6. Adsorption thermodynamic parameter

Change in the Gibbs free energy (�G◦) indicates the degree ofthe spontaneity. For significant adsorption to occur �G◦ must benegative. The �G◦ is defined as:

�G◦ = −RT ln K (7)

According to thermodynamics, the Gibbs free energy change is alsorelated to the entropy change and heat of adsorption at constanttemperature by the following equation:

�G◦ = �H◦ − T �S◦ (8)

where �G◦ is the Gibbs free energy change (kJ/mol), �H◦ is thechange in enthalpy (kJ/mol), �S◦ is the entropy change (J/mol K),and T is the absolute temperature.

b)

0

10

20

30

40

50

60

0 200 400 600

qe (m

g/g)

Ce (mg/l )

288 K

303 K

318 K

inoline by (a) GAC and (b) BFA. Experimental data points given by symbols and the 10 g/l for BFA.

350 D. Rameshraja et al. / Chemical Engineering Journal 181– 182 (2012) 343– 351

Table 3Isotherm parameters for the removal of quinoline by GAC and BFA (t = 24 h, m = 5 g/l for GAC and m = 10 g/l for BFA).

Isotherms Parameters GAC BFA

Temperature (K) Temperature (K)

288 303 318 288 303 318

Langmuir qe = qmKLCe1+KLCe

KL (L/mg) 0.012 0.014 0.018 0.019 0.014 0.018qm (mg/g) 160 169 175 31 45 46R2 0.993 0.992 0.994 0.980 0.989 0.977

Freundlich qe = KFCe1/n KF (L/mg) 4.77 5.20 6.12 1.03 1.03 1.37

1/n 0.59 0.60 0.61 0.59 0.65 0.64R2 0.997 0.997 0.997 0.991 0.992 0.998

Temkin qe = BT ln(KTCe) B1 3.93 3.46 2.43 2.43 2.49 2.75KT (L/mg) 5.19 8.44 21.48 0.99 1.07 1.30R2 0.895 0.888 0.876 0.955 0.939 0.927

Redlich–Petersonqe = KRCe

1+aRCˇe

aR (L/mg) 0.04 0.04 0.03 0.20 0.28 0.46KR (L/mg) 2.15 2.56 3.02 0.90 1.06 1.58ˇ 0.80 0.82 0.87 0.66 0.56 0.51R2 0.995 0.995 0.997 0.997 0.997 0.998

Table 4Thermodynamics parameters for the adsorption of quinoline onto GAC and BFA (t = 24 h, Co = 10–1000 mg/l, m = 5 g/l for GAC and 10 g/l for BFA).

T (K) K × 10−3 (l/kg) �G◦ (kJ/mol) �H◦ (kJ/mol) �S◦ (J/mol K)

GAC BFA GAC BFA GAC BFA GAC BFA

−15.65 12.64 6.86 112.96 77.78−16.48−18.0

m

A

l

T(taesrcr

3

atcqoqm[ufacaa

288 4260.11 687.20 −20.02

303 4786.13 692.03 −21.36

318 7039.89 904.46 −23.43

The effect of temperature on the equilibrium constant is deter-ined as follows:

d(ln K)dT

= �H◦

RT2(9)

fter integration and rearrangements gives:

n K = −�H◦

RT+ �S◦

R(10)

his is known as Van’t Hoff equation. R is the universal gas constant8.314 × 10−3 kJ/mol K); and K = qe/Ce and is called as linear adsorp-ion distribution coefficient. Thermodynamic parameters obtainedre shown in Table 4. The endothermic nature of process is wellxplained by positive value of �H◦. The negative value of �G◦

uggests that the adsorption process is spontaneous. Increasedandomness at the solid/solution interface with some structuralhanges in the adsorbate and adsorbent system for the quinolineemoval is indicated by the positive value of �S◦ [45].

.7. Desorption study

Very poor desorption for quinoline was observed with the alkalind water in comparison with the strong acids. These low desorp-ion with the alkali and water indicated that there may be someomplex bond formation between the active sites of GAC and theuinoline. HNO3 showed maximum quinoline desorption efficiencyf 24% and 17% from GAC and BFA, respectively. Desorption ofuinoline from spent adsorbents were also tested for the ther-al desorption method as described by Rauthula and Srivastava

24] and Suresh et al. [25]. After thermal desorption of quinoline,

nloaded GAC and BFA were again used for adsorption of quinolineor Co = 1000 mg/l, m = 5 g/l, T = 303 K and t = 24 h, thereafter, loadeddsorbents were again made thermally desorbed by the same pro-edure. This adsorption–desorption cycle was repeated five timesnd results are shown in Fig. 9. It can be seen that the spent GACnd BFA can be reused for several adsorption–desorption cycles.

Fig. 9. Quinoline removal efficiency of GAC and BFA after various thermaldesorption–adsorption cycles.

4. Conclusion

It was found that GAC exhibited significantly higher adsorptioncapacity than BFA for the adsorption of quinoline due to highersurface area. Intra-particle diffusion study showed that the sur-face adsorption and intra-particle transport within the pores ofGAC and BFA controls the adsorption process. Thermodynamic con-stants were evaluated using equilibrium constants which changeswith temperature. The value of �G◦ was found to be negative at alltemperatures indicating the spontaneity of adsorptive treatment.Positive values of �H◦ and �S◦ show the endothermic nature andincrease in disorder of quinoline adsorption.

References

[1] U.S. Environmental Protection Agency, Integrated Risk Information System(IRIS), National Centre for Environmental Assessment, Office of Research andDevelopment, Washington, DC, 2001.

ineerin

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

D. Rameshraja et al. / Chemical Eng

[2] G. Collin, H. Hoke, Quinoline and isoquinoline, in: B. Elvers, S. Hawkins, W.Russey, G. Schulz (Eds.), Ullmann’s Encyclopedia of Industrial Chemistry, A22,VCH, Weinheim, 1993, pp. 465–469.

[3] S. Fetzner, Bacterial degradation of pyridine, indole, quinoline, and their deriva-tives under different redox conditions, Appl. Microbiol. Biotechnol. 49 (1998)237–250.

[4] O.P. Shukla, Microbial transformation of quinoline by a Pseudomonas sp., Appl.Environ. Microbiol. 51 (1986) 1332–1442.

[5] U.S. Environmental Protection Agency, Health and Environmental Effects Pro-file for Quinoline, EPA/600/x-85/355, Environmental Criteria and AssessmentOffice, Office of Health and Environmental Assessment, Office of Research andDevelopment, Cincinnati, OH, 1985.

[6] G.D. Clayton, F.E. Clayton (Eds.), Patty’s Industrial Hygiene and Toxicology, vol.IIA, 3rd revised ed., John Wiley & Sons, New York, 1981.

[7] G. Collin, H. Hoke, B. Indole, in: S. Elvers, M. Hawkins, G. Ravenscroft, Schulz(Eds.), Ullmann’s Encyclopedia of Industrial Chemistry, vol. A14, VCH, Wein-heim, 1989, pp. 167–170.

[8] G. Collin, H. Hoke, pitch. Tar, in: B. Elvers, S. Hawkins, W. Russey (Eds.), Ull-mann’s Encyclopedia of Industrial Chemistry, vol. A26, VCH, Weinheim, 1995,pp. 91–127.

[9] S. Zhu, P.R.F. Bell, P.F. Greenfield, Isotherm studies on sorption of pyridine andquinoline onto Rundle spent shale, Fuel 67 (1988) 1316–1320.

10] J. Moon, K.K. Dons, K.L. Won, Adsorption equilibria for m-cresol, quinoline, and1-naphthol onto silica gel, Korean J. Chem. Eng. 6 (3) (1989) 172–178.

11] S. Zhu, P.R.F. Bell, P.F. Greenfield, Quinoline adsorption onto combusted rundlespent shale in dilute aqueous solution at the natural pH 8, Water Res. 29 (5)(1995) 1393–1400.

12] W. Burgos, P. Nipon, M.C. Mazzarese, J. Chorover, Adsorption of quinoline tokaolinite and montmorillonite, Environ. Eng. Sci. 19 (2) (2002) 59–68.

13] L.I. Vico, S.G. Acebal, Some aspects about the adsorption of quinoline on fibroussilicates and Patagonian saponite, Appl. Clay Sci. 33 (2006) 142–148.

14] W. Burgos, N. Pisutpaisal, Sorption of naphthoic acids and quinoline compoundsto estuarine sediment, J. Contam. Hydrol. 84 (2006) 107–126.

15] G. Santarossa, M. Iannuzzi, A. Vargas, A. Baiker, Adsorption of Naphtha-lene and quinoline on Pt, Pd and Rh: a DFT study, Chem. Phys. 9 (2008)401–413.

16] H. Zhang, L. Gang, Yuhua Jia, Haiou Liu, Adsorptive removal of nitrogen-containing compounds from fuel, J. Chem. Eng. Data 55 (2010) 173–177.

17] J.P. Kushwaha, V.C. Srivastava, I.D. Mall, Treatment of dairy wastewater bycommercial activated carbon and bagasse fly ash: parametric, kinetic andequilibrium modelling, disposal studies, Bioresour. Technol. 101 (10) (2010)3474–3483.

18] V.C. Srivastava, I.D. Mall, I.M. Mishra, Treatment of pulp and paper mill wastew-aters with poly aluminium chloride and bagasse fly ash, Colloid Surface A:Physicochem. Eng. Aspects 260 (2005) 17–28.

19] V.C. Srivastava, B. Prasad, I.D. Mall, M. Mahadevswamy, I.M. Mishra, Adsorptiveremoval of phenol by bagasse fly ash and activated carbon: equilibrium, kineticsand thermodynamics, Colloid Surf. A: Physicochem. Eng. Aspects 272 (2006)89–104.

20] V.C. Srivastava, B. Prasad, I.M. Mishra, I.D. Mall, M. Mahadevswamy, Predictionof breakthrough curves for sorptive removal of phenol by bagasse fly ash packedbed, Ind. Eng. Chem. Res. 47 (2008) 1603–1613.

21] V. Mane, I.D. Mall, V.C. Srivastava, Use of bagasse fly ash as an adsorbent for the

removal of brilliant green dye from aqueous solution, Dyes Pigments 73 (2007)269–278.

22] V.C. Srivastava, I.D. Mall, I.M. Mishra, Multi-component adsorption study ofmetal ions onto bagasse fly ash using Taguchi’s design of experimental method-ology, Ind. Eng. Chem. Res. 46 (2007) 5697–5706.

[

[

g Journal 181– 182 (2012) 343– 351 351

23] V.C. Srivastava, I.D. Mall, I.M. Mishra, Antagonistic competitive equilibriummodeling for the adsorption of ternary metal ions mixtures onto bagasse flyash, Ind. Eng. Chem. Res. 47 (9) (2008) 3129–3137.

24] M.S. Rauthula, V.C. Srivastava, Studies on adsorption/desorption of nitroben-zene and humic acid onto/from activated carbon, Chem. Eng. J. 168 (2011)35–43.

25] S. Suresh, V.C. Srivastava, I.M. Mishra, Isotherm, thermodynamics, desorptionand disposal study for the adsorption of catechol and resorcinol onto granularactivated carbon, J. Chem. Eng. Data 56 (4) (2011) 811–818.

26] S. Suresh, V.C. Srivastava, I.M. Mishra, Study of catechol and resorcinol adsorp-tion mechanism through granular activated carbon characterization, pH andkinetic study, Sep. Sci. Technol. 46 (11) (2011) 1750–1766.

27] J.P Chen, L. Wang, Characterization of metal adsorption kinetic properties inbatch and fixed-bed reactors, Chemosphere 54 (2004) 397–404.

28] J.S. Zogorski, S.M. Faust, J.M. Hass, The kinetics adsorption of phenols by gran-ular activated carbon, J. Colloid Interface Sci. 55 (2) (1976) 329–341.

29] P.K. Malik, Use of activated carbons prepared from sawdust and rice-husk foradsorption of acid dyes: a case study of Acid Yellow 36, Dyes Pigments 56 (2003)239–249.

30] T. Robinson, B. Chandran, P. Nigam, Effect of pretreatments of three wasteresidues, wheat straw, corncobs and barley husks on dye adsorption, Bioresour.Technol. 85 (2002) 119–124.

31] Y.S. Ho, G. McKay, Sorption of dye from aqueous solution by peat, Chem. Eng.J. 70 (1998) 115–124.

32] Y.S. Ho, G. McKay, Pseudo-second order model for adsorption processes, ProcessBiochem. 34 (1999) 451–465.

33] D.W. Marquardt, An algorithm for least-squares estimation of nonlinear param-eters, J. Soc. Ind. Appl. Math. 11 (1963) 431–441.

34] R. Aravindhan, J.R Rao, B.U. Nair, Removal of basic yellow dye from aqueoussolution by adsorption on green algae: Caulerpa scalpelliformis, J. Hazard. Mater.142 (2007) 68–76.

35] W.J. Weber Jr., J.C. Morris, Kinetics of adsorption on carbon from solution, J.Sanitary Eng. Div. ASCE 89 (1963) 31–59.

36] D. Kavitha, C. Namasivayam, Experimental and kinetic studies on methyleneblue adsorption by coir pith carbon, Bioresour. Technol. 98 (2007) 14–21.

37] O. Gercel, A. Ozcan, A.S. Ozcan, H.F. Gercel, Preparation of activated carbon froma renewable bio-plant of Euphorbia rigida by H2SO4 activation and its adsorp-tion behavior in aqueous solutions, Appl. Surf. Sci. 253 (2007) 4843–4852.

38] F.C. Wu, R.L. Tseng, R.S. Juang, Comparisons of porous and adsorption propertiesof carbons activated by steam and KOH, J. Colloid Interface Sci. 283 (2005)49–56.

39] Z. Aksu, E. Kabasakal, Batch adsorption of 2,4-dichlorophenoxy-acetic acid (2,4-D) from aqueous solution by granular activated carbon, Sep. Purif. Technol. 35(2004) 223–240.

40] V.C. Srivastava, I.D. Mall, I.M. Mishra, Adsorption thermodynamics and isostericheat of adsorption of toxic metal ions onto bagasse fly ash (BFA) and rice huskash (RHA), Chem. Eng. J. 132 (1–3) (2007) 267–278.

41] I. Langmuir, The adsorption of gases on plane surfaces of glass, mica and plat-inum, J. Am. Chem. Soc. 40 (1918) 1361–1403.

42] H.M.F. Freundlich, over the adsorption in solution, J. Phys. Chem. 57 (1906)385–471.

43] M.J. Temkin, V. Pyzhev, Kinetics of ammonia synthesis on promoted iron cata-lysts, Acta Physiochim. URSS 12 (1940) 217–222.

44] O. Redlich, D.L. Peterson, A useful adsorption isotherm, J. Phys. Chem. 63 (1959)1024–1026.

45] Y. Onal, C. Akmil-Basar, D. Eren, C. Sarıc-Ozdemir, T. Depci, Adsorption kineticsof malachite green onto activated carbon prepared from tunc bilek lignite, J.Hazard. Mater. B128 (2006) 150–157.