Equilibrium, thermodynamic and kinetics studies on adsorption of eosin Y and red X-GRL from aqueous solution by treated rice husk

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1 P a g 392 Journal of Applid Rsarch in Watr and Wastwatr 9(2018) Original papr Equilibrium, thrmodynamic and kintics studis on adsorption of osin Y and rd X-GRL from aquous solution by tratd ric husk Saidh Fatmh Shafii Darabi 1, adr Bahramifar 2,*, Mohamad Ali Khalilzadh 1 1 Dpartmnt of Applid chmistry, Islamic Azad Univrsity Qamshar anch, Iran. 2 Dpartmnt of chmistry, Payam oor Univrsity (PU), Thran, Iran. ARTICLE IFO Articl history: Rcivd 13 May 2018 Rcivd in rvisd form 30 May 2018 Accptd 17 Jun 2018 Kywords: Eosin Y Rd X Tratd Ric husk Adsorption Thrmodynamic ABSTRACT Prsnt study xplord th adsorptiv charactristics of osin Y and rd X dys from aquous solution onto tratd ric husk (TRH). Batch xprimnts wr carrid out to dtrmin th influnc of paramtrs liks initial ph, adsorbntdos, contact tim and initial concntration on th rmoval of osiny and rd X. Th adsorption kintics of th two dys on to TRH was found to follow psudo-scondordr kintic modl. Th quilibrium data is succssfullyfittd to th Frundlich and Langmuir adsorption isothrm for osin Y and rd X, rspctivly. Th thrmodynamic analysis indicatd that th sorption procss was ndothrmic for osin Y and xothrmic for rd X and th ngativ valu of chang in Gibbs fr nrgy indicatd fasibl and spontanous adsorption for both of dys. Th rmoval prcntag of dyswas about 90% (q = mgg -1 ) for osin Y and % for rd X(q=32.44mgg -1 ). Ovrall, th prsnt findings suggst that this nvironmntally frindly, fficint and low-cost adsorbnt is usful for th rmoval of osin Y and rd X from aquous solution Razi Univrsity-All rights rsrvd. 1. Introduction Most of th synthtic dys ar xtnsivly usd in svral filds such as in txtil industris, lathr tanning, papr production, food tchnology, agricultural rsarch, light harvsting arrays, ptrochmical clls and in hair colorings (Robinson t al. 2002). Synthtic dys ar usually rlasd into th nvironmnt from such industrial fflunts and th discharg of highly colord synthtic dy fflunts can b vry damaging to th rciving watr bodis. Morovr, dys usd in th txtil industry may b toxic to aquatic organisms and can b rsistant to natural biological dgradation. Hnc, th rmoval of color synthtic organic dystuff from wast fflunts bcoms nvironmntally important (Hamd 2009). Eosin Y, a coal tar- xanthn dy, was chosn as th modl anionic dy to avoid nvironmntal hazards during invstigation (Chattrj t al. 2005).Cationic Rd X-GRL, an azo dy, was slctd as th modl pollutant for this study bcaus it is not biodgradabl by th convntional activatd sludg procss, and it is widly usd in txtil, color solvnt, ink, paint, varnish, papr, and plastic industris (Zhou and H 2008).Diffrnt physic-chmical procsss lik lctro-kintic coagulation, ion-xchang, mmbran filtration, lctrochmical oxidation, and photo-catalytic dgradation procss hav bn usd for th tratmnt of dy-containing fflunts (Hachm t al. 2001; Gmay t al. 2003; Aksu and Karabayır 2008; Rira-Torrs and Gutiérrz 2010; Cisnros t al. 2002). Howvr, thr ar crtain short comings. Coagulation procss producs larg amount of has no loss of adsorbnt on rgnration, howvr, it cannot accommodat wid rang of dys, and is xpnsiv. Mmbran sparation procss is also ffctiv in rmoval of dys, howvr, du to rlativly high invstmnt and mmbran fouling problm, its application is rstrictd. Adsorption is a wll-known quilibrium sparation procss and an ffctiv mthod for watr dcontamination applications (Dabrowski 2001). Th adsorption procss provids an attractiv altrnativ tratmnt, spcially if th adsorbnt is inxpnsiv and radily availabl. This procss is bcoming an attractiv and promising tchnology bcaus of its simplicity, as of * Corrsponding author nbahramifar@yahoo.com opration and handling, sludg fr opration, and rgnration capacity. Adsorption producs a high quality product, and is a procss which is conomically fasibl (Gupta and Suhas 2009). Almost complt rmoval of impuritis with ngligibl sid ffcts xplains its wid application for th tratmnt of dy baring wastwatrs. Activatd carbon adsorption procss for th rmoval of dys is an accptd practic. Howvr, AC is xpnsiv and its rgnration and rus mak it mor costly (Fan t al. 2010). Consquntly, many invstigators hav studid th fasibility of using low-cost substancs for th rmoval of various dys and pollutants from wast watrs (Man t al. 2007). Svral rcnt publications utilizd diffrnt inxpnsiv and locally abundantly availabl adsorbnts lik bagass (Ahmdna t al. 2000; Valix t al. 2004; Conrad and Hansn 2007) coir (amasivayam t al. 2001; Kadirvlu t al. 2003), banana pith (Banat t al. 2003), dat pits (Kannan and Sundaram 2001), straw (Mohamd 2004) and ric husk (Kadirvlu t al. 2000; Fng t al. 2004; Chuah t al. 2005). Ric husk is an agricultural wast, accounting for about on-fifth of th annual gross ric production (545 million mtric tons) of th world andchosn as an adsorbnt in svral watr tratmnt procsss (Purkait t al. 2005). In natur, ric husk is tough, insolubl in watr, woody and charactrizd by its abrasiv inhrnt rsistanc bhavior and silicacllulos structural arrangmnt (Daifullah t al. 2004). Its major organiccomponnts of cllulos, hmicllulos, lignin and inorganic componnts of ric husks ar found to b SiO 2, H 2O, Al 2O 3, F 2O 3, K 2O, a 2O, CaO and MgO (Purkait t al. 2005; Chandraskhar t al. 2005; Foo and Hamd 2009; Hamd 2009). Ric husk has good adsorptiv proprtis and has bn usd for th rmoval of various havy mtals (El-Shafy 2007; aiya t al. 2009); dys (Chakraborty t al. 2011; Malik t al. 2003; Mohamd 2004), tc. Th main objctiv of this work is to study th adsorption potntial of low-cost bioadsorbnt, tratd ric husk for th rmoval of hazardous dys osin Y and rd X from th aquous solution. Th ffct of dy concntration, adsorbnt dos, tmpratur, and ph of th mdium, on Plas cit this articl as: S.F.S. Darabi,. Bahramifar, M. A. Khalilzad, Equilibrium, thrmodynamic and kintics studis on adsorption of osin Y and rd X-GRL from aquous solution by tratd ric husk, Journal of Applid Rsarch in Watr and Wastwatr, 5 (1), 2018,

2 P a g 393 Darabi t al. / J. App. Rs. Wat. Wast. 9(2018) th adsorption charactristic of prtratd TRH in ordr to mak a comparison btwn thm. Also th adsorption isothrm modls and various thrmodynamic paramtrs wr studid. 2. Matrials and mthods 2.1. Tratmnt of th adsorbnt atural ric husk was collctd from local ric-mill of north, Iran. It was sparatly washd with distilld watr to rmov dust lik impuritis and was drid in hot air ovn (D-783 Emmndiogon 14) at 80 ο c for ovrnight. atural ric husk was rfluxing with aoh 8% (w/w) at wight ratio 1:6 and hatd to boiling for 6h, th filtrat is washd twic with distilld watr and 10% HCl was addd to ph=7. Thn sivd (Damavand, Tst siv LTD, ASTM: 11) with100 msh and was usd for th batch xprimnt. Th formd prcipitat of silica was washd, drid at 100 C and thus th silica xtractd by alkalin tratmnt was usd as a sorbnt matrial in this work Adsorbat Th dys usd in th prsnt work wr osin Y (Mrck, 98.7%), which is anionic in natur and rd X-GRL (5-[4-(bnzyl-mthylamino phnylazo]-1,4-dimthyl-4h-[1,2and 4]triazol-1-ium chlorid) (Mrck, 99.5%) usd in th prsnt work was purifid from industrial cationic rd X-GRL. Th structurs of th dys ar shown in Fig.1. Synthtic stock dy solutions wr prpard by dissolving 0.1g of dys in 100mL of distilld watr. HO O O COOH Fig.1. Structur of osin Y, rd X. Cl 2.3. Batch adsorption xprimnts Th adsorption xprimnts wr carrid out in a batch procss. Various paramtrs such as, initial dy concntration, adsorbnt amount, tmpratur and ph of th mdium wr studid. For ach xprimntal run, 150 ml of dys solution of known concntration, ph 0 and a known adsorbnt dos wr takn in a 250 ml Erlnmyr's flask. Th initial ph adjustmnts wr carrid out ithr by hydrochloric acid or sodium hydroxid solutions bfor adding th TRH. Th ffcts of tmpratur on th adsorption data wr carrid out by prforming th adsorption xprimnts at various tmpraturs (15, 25, 35 and 45 C) and th kintics and isothrms for th adsorption data wr studid undr optimizd condition of ph. Th flasks wr agitatd at a constant spd of 170 rpm for 3 h in an incubator shakr (Modl Jal tajhiz, TSL20) at 30 C. Dfinit volums of 5ml of sampls wr at tim intrvals of 5, 15, 25, 35, 60, 90, 120,150 and 180 min (Hamd 2009). Th collctd sampls wr thn cntrifugd and th concntrations in th suprnatant solution wr dtrmind using UV-visspctro photomtr (cintra, GBC) at an absorbanc wavlngth of 510 and 520 nm for osin Y and rd X, rspctivly. Th amount of adsorption at quilibrium, q (mgg -1 ), was calculatd by: q = (C 0 C ) V/ W (1) whr C 0 and C (mgl -1 ) ar th liquid-phas concntrations of dya t initial and quilibrium, rspctivly. V (L) is th volum of th solution and W (g) is th mass of dry sorbnt usd. Th dy rmoval prcntag can b calculatd as follows: R %=[(C 0 C )/C 0] 100 (2) 3. Rsults and discussion 3.1. Charactrization of TRH A Fourir transformation infrard (FTIR) spctrum of TRH was obtaind using K pllts in conjunction with Shimadzu FTIR 8400S spctromtr. Th pllt for infrard studis was prpard by mixing a givn sampl with K crystals and prssd into a pllt. A spctrum was rcordd in th mid- IR rang from 4000 to 400 cm 1 with a rsolution of 1 cm 1.Th rsults of FTIR of th outr surfacs of aoh tratd ric husks ar shown in Fig. 2. FTIR spctra showd that tratd ric husk containd functional groups of th standard polymrs α-cllulos, and coir pith lignin. This figur shows a broadband btwn 2900 and 3750 cm -1 with littl about 3400 cm -1 which indicat th prsnc of both fr and hydrogn bondd OH groups and Si-OH groups on th adsorbnt surfac. This strtching is du to both th silanol groups (Si-OH) and adsorbd watr (about at 3400 cm -1 ) on th surfac (Abou-Msalam t al. 2003). Th FTIR spctrum of TRH shows paks in th rgion of 1650 and 1512 cm -1. Th broad pak in th rgion of 1650 cm -1 indicats th prsnc of CO group strtching from aldhyds and ktons. Th band at 1650 cm -1 may also b du to conjugatd hydrocarbon bondd carbonyl groups. Th sharp pak at 1512 cm -1 indicats th prsnc of primary amids and signifis C- strtching and -H in-plan bnding. Th pak at 1512 cm -1 may also b du to th -O 2 group symmtric strtching. Th band around 1512 cm -1 in TRH may also b attributd to th carboxyl carbonat structurs (Ricordl t al. 2001). Th paks at about 1033 cm -1 indicat th prsnc of Si-O-Si (Sharma t al. 2010) Effct of ph Th ph valu of th solution is an important factor that must b considrd during adsorption studis. In th prsnt adsorption systm, th ffct of ph was invstigatd for valus btwn 1-9 and th rsult wr prsntd for th both dys in Fig. 3. As shown,for osin Yat ph=2, thmost prcntag of dy rmovalwas about 90% for an initial dy concntration of 100 mgl -1 (q =31.72) and it dcrasd up to ph=4, thn rmaind narly constant (70.35mgg -1 ) ovr th initial ph rangs of 4 9.TRH contains diffrnt nuclophilic functional groups such as carboxyl and hydroxyl.it was suggstd that th adsorption of osiny onto TRH may b du to lctrostatic attraction btwn anionic dy molculs and positiv chargd functional groups prsnt on th surfac of th adsorbnts. This is du to th fact that th dy molculs bcom nuclophilic at highr ph (basic ph) which rsults in lss adsorption on th nuclophilic sits of th TRH (Lakshmi t al. 2009). Howvr, it has bn found that dy's adsorption incrass with incras in ph for rd X, and maximum adsorption is found around a ph valu of 8(q =32.44mgg -1, R = 93.44%). This may b du to th fact that at highr ph valus, th surfac of adsorbnt bcoms ngativ which nhancs th adsorption of positivly chargd rd X cationic dy through lctrostatic forc of attraction Effct of initial dy concntration (C 0) and contact tim Th ffct of initial dy concntration on th prcntag adsorption of osin Y and rd X dys by TRH ar shown in Fig. 4. It has bn found that with th incras in concntration of th adsorbat, th adsorption prcntag dcrass, whil th amount of dy rmovd at quilibrium incrasd with th incras in dy concntration in both th cass. Th amount of osin Y adsorbd at quilibrium (q ) incrasd from to mgg -1 as th initial concntration was incrasd from 50 to 250 mgl -1, whras th prcntag rmoval dcrasd from to Plas cit this articl as: S.F.S. Darabi,. Bahramifar, M. A. Khalilzad, Equilibrium, thrmodynamic and kintics studis on adsorption of osin Y and rd X-GRL from aquous solution by tratd ric husk, Journal of Applid Rsarch in Watr and Wastwatr, 5 (1), 2018,

3 P a g 394 Darabi t al. / J. App. Rs. Wat. Wast. 9(2018) % with incras in C 0. Th sam rsults wr obtaind for rd X, q incrasd from to mgg -1, whil th prcntag rmoval dcrasd from to 60.27% with incras in C 0. This is so bcaus th initial dy concntration provids th driving forc to ovrcom th rsistanc to th mass transfr of dy btwn th aquous and solid phas. Th incras in initial concntration also nhancs th intraction btwn adsorbnt and dy. Thrfor, an incras in initial concntration of dy solution nhancs th adsorption uptak of dy (Sharma t al. 2010). Adsorbat and adsorbnt contact tim is grat importanc in adsorption procss, bcaus it dpnds on th natur of th systm usd. Th ffcts of quilibration tim on adsorption of osin Y and rd X dys onto TRH ar prsntd in Fig. 4. Th obtaind rsults show that as th contact tim incrass, th rat of adsorption incrass first and thn rmains almost constant. Fig. 4 illustratd that th rat of adsorption of dys wr vry fast during th initial stag of th adsorption procsss. Aftr fast initial rat of adsorption, uptak capacity for both th dys incrasd with th tim, and rachd quilibrium valu at about 25 min, sinc maximum adsorption is attaind during this priod. Th concntration gradint will b rsponsibl for ths changs in th rat of adsorption. In th bginning, bcaus of high concntration gradint, th driving forc hlpd in this rapid adsorption. This rapid initial uptak of dys may b an important paramtr for a practical application of adsorption in industrial wastwatr. paramtrs such as chang in fr nrgy (ΔG ), nthalpy (ΔH ), and ntropy (ΔS ) wr dtrmind using th following quation: G H S (3) q S H log C 2.303R 2.303RT whr q is th maximum amount of dy (mg) adsorbd pr unit mass of th TRH (mgg -1 ), C is th quilibrium concntration (mgl -1 ) of th dy in th solution, T is th solution tmpratur (ink), and R is th univrsal gas constant. ΔH and ΔS wr calculatd from th slop and intrcpt of van, t Hoff plots of log (q /C ) vrsus T -1 (Purkait t al. 2005). Using Eq. (4), standard nthalpy and th ntropy changs of sorption procss wr dtrmind from th log (q /C ) vrsust -1 plots (Fig. 7), and ar also rprsntd in Tabl 1. For osin Y; th ΔG valus indicat that th adsorption procss is spontanous in natur. Th positiv valu of ΔH suggsts that th adsorption procss is ndothrmic and favorabl at highr tmpratur. Whil, for rd X, th ngativ valus of ΔG and ΔH indicat that th adsorption procss is spontanous and xothrmic in natur. (4) 3.4. Effct of adsorbnt dosag Fig. 2. IR spctra of TRH. Th ffct of adsorbnt dosag on dy adsorption wr conductd at initial dy concntration of 100 mgl -1. Fig. 5 shows th ffct of adsorbnt dosag on th rmoval of osin Y and rd X. Th dy uptak dcrasd from mgg -1 to mgg -1 for an incras in adsorbnt dosag from 1gL -1 to 5g -1 for osin Y.Whras th prcntag rmoval incrass from to 83.26%.For rd X, q dcrasd from to mgg -1, butth rmoval incrass from to 44.3 % with incrasing adsorbnt dosag. For both dys, it was obsrvd that th amount of q was found to dcras with incrasing adsorbnt dosag. This ffct can b xplaind on th basis of solut distribution btwn th adsorbnt and bulk dy solution.according to figur, th rmoval incrass with th incras adsorbnt dosag. This indicats that with an incras of sorbnt mass, mor surfac ara is mad availabl, and so isavailability of mor adsorption sits. But adsorption capacity dcrasd with incras in adsorbnt dosag (Ho and McKay 1998) Effct of tmpratur and thrmodynamic analysis Th ffct of tmpratur on th adsorption of osin Y and rd X by TRH was shown in Fig. 6. For osin Y as you can s, quilibrium adsorption capacity incrass from to 42.34mgg -1, whras for rd X, q dcrasd from 31.62to 23.34mgg -1, whn th tmpratur is raisd from 15 to 45 C. Bttr adsorption at highr tmpratur for osin Y may b ithr du to acclration of som originally slow sorption stps or du to cration of nw activ sits on th sorbnt surfac. Thus an incras in tmpratur will rduc th lctrostatic rpulsion btwn th surfac and th adsorbing spcis, allowing adsorption to occur mor radily. This could also b du to nhancd mobility of dy molculs from solution to th adsorbnt surfac (Sharma t al. 2010). Thrmodynamic Fig. 3. Effct of ph on th prcntag of rmoval dys of osin Y and rd X onto TRH (Dy concntration = 100 mgl -1, tmpratur = 30 C) Isothrm analysis In ordr to optimiz th dsign of adsorption systm to rmov dys from aquous solutions, it is important to stablish th most appropriat corrlation for th quilibrium curvs. Th quilibrium isothrms in this study wr analyzd using th Langmuir, Frundlich and Tmkin isothrms (Fig. 8). Th Frundlich isothrm is drivd by assuming a htrognous surfac with a non-uniform distribution of hat of adsorption ovr th surfac. Whras, in th Langmuir thory, th basic assumption is that th sorption taks plac at spcific homognous sits within th adsorbnt. Th Langmuir isothrm is rprsntd by th following linar quation: C q 1 (5) q b m C q m whr C (mgl -1 ) is th quilibrium concntration, q (mgg -1 ) th amount of adsorbat adsorbd pr unit mass of adsorbat, and q m and b ar Langmuir constants rlatd to adsorption capacity and rat of adsorption, rspctivly (Langmuir 1918). Th Langmuir constants b and q m wr calculatd from this isothrm and thir valus ar listd in Tabl 2. Th ssntial faturs of th Langmuir isothrm can b xprssd in trms of th dimnsionlss quilibrium paramtr R L, which is dfind as R L = 1/ (1+bC 0), whr b (Lmg -1 ) is th Langmuir constant as dscribd abov, and C 0 is th initial dy concntration. R L valus within th rang 0 < R L<1 indicat favorabl adsorption. Th Frundlich isothrm is an mpirical rlationship showing th intraction btwn adsorbat molculs and htrognous surfacs. Th linar quation is xprssd as follows: Plas cit this articl as: S.F.S. Darabi,. Bahramifar, M. A. Khalilzad, Equilibrium, thrmodynamic and kintics studis on adsorption of osin Y and rd X-GRL from aquous solution by tratd ric husk, Journal of Applid Rsarch in Watr and Wastwatr, 5 (1), 2018,

4 P a g 395 Darabi t al. / J. App. Rs. Wat. Wast. 9(2018) ln( q ) ln( K ) (1/ n)ln( C ) (6) F whr K F is th Frundlich constant (mgg -1 (mgl -1 ) n) and 1/n is th htrognity factor. Th valu of n indicats whthr th adsorption procss is favorabl or not. Th slop 1/n ranging btwn 0 and 1 is a masur of adsorption intnsity or surfac htrognity, bcoming mor htrognous as its valu gts closr to zro (Frundlich 1907). Th Tmkin isothrm quation assums that th hat of adsorption of all th molculs in th layr dcrass linarly with covrag du to adsorbnt adsorbat intractions that th adsorption is charactrizd by a uniform distribution of th binding nrgis, up to som maximum binding nrgy.th linar form of Tmkin isothrm can b writtn as: whr B=RT/b, T is th absolut tmpratur in Klvin and R is th univrsal gas constant (8.314 J mol -1 k -1 ). A is th quilibrium binding constant and B is corrsponding to th hat of sorption (Tmkin 1941). Th adsorption data wr analyzd according to E q. (7). Th corrlation cofficints for both dys wr low and it can b said that th xprimntal data was not fittd bttr to th Tmkin isothrm modl. Th rsults indicatd that th surfac of ric husk is htrognous in natur and did not possss qual distribution of binding nrgis on th availabl binding sits. Th valus of th paramtrs ar givn in Tabl 2. From Tabl, th Frundlich and Langmuirisothrm modls yildd th bst fit with th highst R 2 valu (0.906,0.999) for osin Y and rd X, rspctivly. q Bln( A) Bln( C ) (7) Fig. 4. Effct of initial concntration on th adsorption of osin Y (PH=2, W= 3gL -1 ), rd X (ph=8, W= 4gL -1 ) on TRH. Fig.5. Effct of adsorbnt dosag on th adsorption of osin Y onto TRH (ph=2, c 0=100mgL -1, contact tim= 180 min), rd X (ph=8, c 0=100 mgl -1, contact tim= 180 min) Adsorption kintics Various kintic modls, namly psudo-first-ordr, psudo-scondordr and intraparticl diffusion modls hav bn usd for thir validity with th xprimntal adsorption data for dys onto TRH. Th study of adsorption kintics dscribs th solut uptak rat, and vidntly ths rats control th rsidnc tim of adsorbat uptak at th solid solution intrfac, including th diffusion procss. Th mchanism of adsorption dpnds on th physical andchmical charactristics of th adsorbnt as wll as on th masstransfr procss (Abou-Msalam 2003). Th psudo-first-ordr kintic modl has bn widly usd to prdict dy adsorption kintics. A linar form of psudo-first ordr modl was dscribd by Lagrgrn (1898): log( q q ) log( q ) ( K / t (8) t ) whr q and q t ar th adsorption capacitis (mgg -1 ) at quilibrium and at tim t, rspctivly; K 1 is th rat constant of psudo-first ordr adsorption (L min -1 ). Th plot of log(q -q t) vrsus t, givs a straight lin for th first-ordr adsorption kintics as shown in Fig. 9a. Th valu of th first-ordr rat constant k 1 is obtaind from th slop of th straight lin. Th obtaind curvs by plotting log (q - q t) vrsus t, did not show a straight- lin during th whol adsorption procss, indicating that psudo-first ordr kintics could not b usd to dscrib th adsorption bhavior of anionic dys onto TRH. Th valus of th paramtrs ar givn in Tabl 3. Th psudo-scond-ordr rat quation of McKay and Ho can b rprsntd in th following form (Ho and McKay 1998): t 2 2q t / q 1/ K t / q (9) Plas cit this articl as: S.F.S. Darabi,. Bahramifar, M. A. Khalilzad, Equilibrium, thrmodynamic and kintics studis on adsorption of osin Y and rd X-GRL from aquous solution by tratd ric husk, Journal of Applid Rsarch in Watr and Wastwatr, 5 (1), 2018,

5 P a g 396 Darabi t al. / J. App. Rs. Wat. Wast. 9(2018) whr th quilibrium adsorption capacity q, and th psudo-scondordr constants K 2 (gmg -1.min -1 ) can b dtrmind xprimntally from th slop, and intrcpt of plot t/q t vrsus t, Fig.9b.Th corrlation cofficints for th scond-ordr kintic modl wr clos to narly 1.0 for th both cass, and th thortical valus of q q also agrd wll with th xprimntal data. On th othr hand, th corrlation cofficints for th psudo first-ordr kintics wr lowr than thos of psudo scond-ordr on. In addition, th thortical q valus calculatd from th first-ordr kintic modl did not giv rasonabl valus with obvious dviation from th xprimntal ons. Fig. 6. Effct of tmpratur on th adsorption capacity of osin Y and rd X on TRH. Fig. 7. Van't Hoff plot for th adsorption of osin Y rd-x on TRH Exprimntal data Langmuir Frundlich Tmkin q, mg/g 40 q, mg/g Exprimntal data Langmuir Frundlich Tmkin C, mg/l C, mg/l Fig. 8. Comparison of various isothrm quations for th adsorption of Eosin Y and Rd X at Constant tmpraturs by TRH (t = 3 h, C 0= mgl -1 ). Plas cit this articl as: S.F.S. Darabi,. Bahramifar, M. A. Khalilzad, Equilibrium, thrmodynamic and kintics studis on adsorption of osin Y and rd X-GRL from aquous solution by tratd ric husk, Journal of Applid Rsarch in Watr and Wastwatr, 5 (1), 2018,

6 P a g 397 Darabi t al. / J. App. Rs. Wat. Wast. 9(2018) Fig.9. Psudo-scond-ordr kintics for th adsorption of osin Y, rd X onto TRH. Dy Concntration (mgl -1 ) Tabl 1. Thrmodynamic paramtrs for th adsorption of osin Y and rd X on TRH. Typ of dy Eosin Y Rd X H (kj mol -1 ) S (J mol -1 K -1 ) G (J mol -1 ), At diffrnt tmpratur Tabl 2. Isothrm paramtrs for rmoval of dys by TRH. Langmuir isothrm Frundlich isothrm Tmkin isothrm Typ Q dy max K b (Lmg R R F R 2 B A R (mgg -1 ) -1) 2 [(mg -1 g)(mgl -1 ) n ] 2 L Eosin Y Rd X Dy Eosin Y Rd X Tabl 3. Kintic paramtrs for th rmoval of dys by TRH. psudo-first ordr kintic modl Psudo-scond ordr kintic modl K 1 (min -1 ) q (mgg -1 ) R 2 q xprimntal (mgg -1 ) K 2 (gmg -1 min -1 ) q (mgg -1 ) R Conclusions Th prsnt study shows that TRH is an ffctiv adsorbnt for th rmoval of both cation (osin Y) and anion (rd X) dys from aquous solution. Morovr, it was shown that TRH had a much highr quilibrium adsorption capacity on rd X than on osin Y. Th adsorption capacity of dy was slightly changd by ph. Th amount of dys uptak was found to incras with th incras of initial concntration and adsorbnt dos. Th adsorption kintic studis showd that th adsorption procss followd psudo-scond-ordr kintic modl. Th Langmuir, Frundlich and Tmkin adsorption isothrm modls wr applid to th adsorption data of dys onto TRH. Th Frundlich and Langmuir isothrm bst fittd th adsorption quilibrium data for osin Y and rd X dys, wr studid rspctivly. Th procss is ndothrmic for osin Y, whil for rd X dy is xothrmic. Th ngativ valu of ΔG 0 indicatd spontanous adsorption for both of dys on TRH. Th intraction procsss wr accompanid by an incras of ntropy valu. This study concluds that th TRH could b mployd as low-cost adsorbnt for th rmoval of osin Y and rd X dys from aquous solution. Rfrncs Abou-Msalam M.M., Sorption kintics of coppr, zinc, cadmium and nickl ions on synthsizd silico-antimonat ion xchangr, Colloids and Surfacs A: Physicochmical and Enginring Aspcts 225 (2003) Ahmdna M., Marshall W.E., Rao R.M., Production of granular activatd carbons from slct agricultural by-products and valuation of thir physical, chmical and adsorption proprtis1, Biorsourc tchnology 71 (2000) Aksu Z., Karabayır G., Comparison of biosorption proprtis of diffrnt kinds of fungi for th rmoval of Gryfalan Black RL mtal-complx dy, Biorsourc Tchnology 99 (2008) Plas cit this articl as: S.F.S. Darabi,. Bahramifar, M. A. Khalilzad, Equilibrium, thrmodynamic and kintics studis on adsorption of osin Y and rd X-GRL from aquous solution by tratd ric husk, Journal of Applid Rsarch in Watr and Wastwatr, 5 (1), 2018,

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