Effect of cationic and anionic dye adsorption from aqueous solution by using chemically modified papaya seed

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1 11 Intrnational Confrnc on Environmnt Scinc and Enginring IPCBEE vol.8 (11) (11) IACSIT Prss, Singapor Effct of cationic and anionic dy adsorption from aquous solution by using chmically modifid papaya sd N. Nasuha, H.Z. Zurainan, H.I. Maarof, N.A. Zubir, N. Amri Faculty of Chmical Enginring Univrsiti Tknologi Mara (UiTM) Prmatang Pauh, 135 Pulau Pinang, Malaysia -mail: Abstract Papaya sd (PS) was modifid using chmically strification of carboxyl group to improv prformanc in adsorption capacity for rmoval cationic and anionic dy from aquous solution. Th opration paramtrs invstigatd includd initial concntrations, (5-5 mg/l) and various adsorbnt ( and ). Th xprimntal data wr analyzd by using Langmuir and Frundlich modls of adsorption. Th adsorption isothrm data for MB wr bst fittd to th Langmuir isothrm and th maximum monolayr adsorption capacity was found to b 25. mg/g and. mg/g at 3 C for and rspctivly, whil for CR for both adsorbnts ( and ) th bst fit xprimntal data wr Frundlich isothrm. Th adsorption kintics can b prdictd by th psudo-first ordr and psudo-scond ordr.th xprimnt data wr obys psudo-scond ordr with highr cofficint of corrlation.99. Th rsult rvald that can b act as good adsorbnt for rmoval anionic dy (CR) and can b rmarkabl as xcllnt adsorbnt modifid of PS for cationic dy rmoval. Kywords-adsorption; mthlyn blu; congo rd; strification, isothrm; kintics I. INTRODUCTION Most of th industris such as txtil, papr, printing, lathr, food, cosmtics, tc. us dys to colour thir final product also consum substantial volum of watr. As a rsult, thy gnrat a considrabl amount of colourd wastwatr. Wastwatr containing dys is vry difficult to trat, sinc th dys ar rcalcitrant organic molculs, rsistant to arobic digstion, and ar stabl to light [1]. Th prsnc of dys vn in vry low concntration is highly visibl and causs damag to th nvironmnt as thy ar toxic to aquatic lif [2, 3]. Mthyln blu and congo rd can b considrd as hazardous chmical bcaus it contnt highly toxic du to th larg numbr of mtal complx dy [4]. Mthyln blu (MB) is th most commonly usd substanc for dying cotton, wood and silk. It can caus y burns which may b rsponsibl for prmannt injury to th ys of human and animals. On inhalation, it can giv ris to short priods of rapid or difficult brathing whil ingstion through th mouth producs a burning snsation and may caus nausa, vomiting, profus swating, mntal confusion and mthmoglobinmia [5]. Congo rd (CR) is a bnzidinbasd anionic bisazo dy known to mtaboliz to bnzidin, a known human carcinogn [6]. CR is toxic to animals and plants and thus its introduction to watr stram is of potntial halth, nvironmntal, and cological concrn. Thrfor, CR and MB containing fflunts hav to b sufficintly tratd bfor thy ar dischargd into th watr bodis. Various mthods hav bn idntifid for th dy rmoval from industrial fflunt includs ion xchang, activatd carbon adsorption, mmbran tchnology and coagulation [7]. Adsorption tchniqus usd activatd carbon has bn found as most fficint mthod usd for rmoval dys. Howvr, it s usd is still limitd bcaus highr th quality of activatd carbon, th gratr it opration costs. Th nd for rgnration and difficulty of sparation from th wastwatr aftr us ar also major concrns associatd with activatd carbon [8]. Today, rsarchrs hav com out with study that has bn focusd on th low-cost adsorbnts that ar mainly obtaind from agricultur wast and industrial by product sinc thy rquird littl procssing and abundant in natur. Plant wasts ar inxpnsiv as thy hav no or vry low conomic valu. Papaya sd is on of th agricultural wasts in Malaysia that can b usd has an altrnativ low cost adsorbnt in ordr to rmov dys from aquous solution. Th sds ar oftn tims discardd as wast. Th fruits hav trmndous nutritional valu and contain 1.5% protin,.1% fat, 7.1% carbohydrats, and 35. caloris pr 1 g dibl fruit. Thy also contain high lvls of calcium, iron, sodium, potassium, carotn, vitamin B2, niacin, and vitamin C [9]. Prviously, som low cost plant wast had dirctly bn usd as adsorbnt for dy adsorption from wastwatr tratmnt. Howvr, th application of untratd plant wast adsorbnt can also bring svral problms such as lowr adsorption capacity, highr chmical oxygn dmand (COD) and biological chmical dmand (BOD) as wll as total organic carbon (TOC) du to th rlasd of solubl organic compound containd in th plant matrial [1]. Thrfor, thr ar nds to modifid agricultur wast product in ordr to incras its adsorption prformanc. This study has bn focusing on th modification mthod of adsorbnt using chmical modification of strification Th comparison on adsorption capacity of cationic and anionic dy onto ths modifid adsorbnts was studid sinc surfac modification alon would substantially dcras th adsorbnt prparation cost [11]. 5

2 II. EXPERIMENTAL III. RESULT AND DISCUSSIONS A. Adsorbnt Papaya sds (PS) usd in this study was obtaind from food factory wast, Simpang Ampat, Pulau Pinang. Th sds wr washd with distilld watr and boild with watr for 4 min. Thn, th sds wr filtrd out bfor bn drid in an ovn at C for 24 h in ordr to liminat its moistur contnt. Th drid matrials wr grindd and sivd into µm to rduc it siz into form of powdr. Th prpard papaya sd sampl was stord in air-tight containr and rfrrd as. B. Adsorbat Stock solution was prpard by dissolving 1. g of (MB) in 1 L distilld watr. It was soakd slowly to mak sur all MB powdr has bn dissolvd in distilld watr. This stock solution was stord for furthr usd. This ntir stp has bn rpatd with CR instad of MB. Th maximum wavlngth for MB is 668 nm whras CR is 5 nm. C. Prparation of Tratd Papaya Sd Estrification was carrid out by suspndd 9. g of papaya sd into 633 ml of 99.9% pur mthanol and 5.4 ml of.1 M HCl solution in a conical flask. Th mixtur was stirrd for 3 hours. Thn th strifid papaya sd was thoroughly washd with distilld watr until rachd ph 7, bfor bn filtrd and drid with C in an ovn for 24 hours. It is thn bn stord for furthr usd. Th sampl was rfrrd as. D. Equilibrium studis This xprimnt was carrid out by adding.5 g of adsorbnt into a six numbr of 25 ml conical flask containing spcific volum ml at diffrnt initial concntration (5-5 mg/l) of dy solution of MB and CR without changing ph and tmpratur. Th flask was placd in an orbital shakr and agitation was providd at 15 rpm for 18 min to mak sur quilibrium was rachd. Th sampls wr takn for vry 5 minuts in first 3 min, aftr that vry 1 min in min and th rst for vry 15 min in 9 min. Final concntration of dy solution wr analyzd using UV-vis spctrophotomtr. Th amount of quilibrium uptak of dys is calculatd by using: ( Co C) V q = 1 (1) W whr C and C (mg/l) ar th liquid-phas concntrations of dy at initial and quilibrium, rspctivly. V (L) is th volum of th solution and W (g) is th mass of PS usd. Th prcntag rmoval dy is dfind as th ratio of diffrnc in dy concntration bfor and aftr adsorption (C o C ) to th initial concntration of dy in th aquous solution (C o ) and was calculatd using th quation: Rmoval prcntag = Co C 1 (2) C o A. Effct of dy adsorption by chmical modification on (MB) and (CR) Fig. 1 shows th influnc of chmical modification on adsorption prcntags of cationic dys. obtaind highst prcntag rmoval btwn to 86.55% compard to that rsultd 91.79% to 69.75% with initial concntration incrasd from 5 to 5 mg/g. It indicats that carboxyl group baring ngativ charg inhibitd th adsorption of anionic dys. In ordr to rmov ngativ charg from carboxyl group by strification, th dy uptaks of CR wr visibly incrasd [12]. Fig.2 shows th ffcts of chmical modification on th prcntag rmoval of anionic dys. From th rsult obtaind, it shows that had highst prcntag in rmoval CR compard to. At quilibrium tim, th %rmoval of is btwn 76.3% to 25.99%compard to that rsultd 57.71% to 26.86% for incrasing in initial concntration of dy solution from 5 to 5 mg/l. This xprimntal rsult provd that carboxyl group was major functional group in th adsorption of cationic dys. B. Effct of initial concntration and contact tim Th ffct on initial concntration (5-5 mg/l) of MB adsorption onto ar prsntd in fig. 3. A rapid incrasd is obsrvd for th first 15 min and it thn procds slowly until rachd quilibrium. This may du to th incrasd in th numbr of vacant surfac sits availabl at initial stag. Th quilibrium adsorption of MB is incrasd from to mg/g as incrasing concntration of MB from 5 to 5 mg/g. It was significant diffrnt with prcntag rmoval that dcrasd from 88.8 to 59.32% as initial concntration incrasd. Th adsorption of MB at low concntration 5 and 1 mg/g achiv quilibrium in lss than min whil in high concntration th tim ncssary to achiv quilibrium was 1 min. % Rmoval of MB C (mg/l) Fig. 1. Influnc of chmical modification on adsorption of MB by papaya sd 51

3 % Rmoval of CR C (mg/l) Fig. 2. Influnc of chmical modification on adsorption of CR by papaya sd Equilibrium uptak, q (mg/g) Tim (min) 5 ppm 1 ppm ppm 3 ppm 4 ppm 5 ppm Fig. 3. Effct of contact tim and initial concntration on th adsorption of MB on Fig. 4 shows th ffct on initial concntration of CR adsorption onto. Equilibrium adsorption of CR onto incrasd from 1.78 to 5.69 mg/g and prcntag rmoval is dcrasd from 53.9 to 25.33% as initial concntration incrasd. Aftr 15 min, adsorption of mthyln blu was procd slowly until it rachd quilibrium saturatd. Data was collctd until 18 min to nsur quilibrium adsorption has bn achivd. C. Adsorption isothrms Th adsorption isothrm rprsnts th rlationship btwn th amount adsorbd by a unit wight of solid adsorbnt and th amount of adsorbat rmaind in th solution at quilibrium tim [13]. Langmuir and Frundlich isothrms ar commonly usd to dscrib th quilibrium charactristic of adsorption. This xprimntal data wr fittd to both isothrm modls. Linar rgrssions wr usd to dtrmin th bst fit modl and last squars has bn widly usd for obtaining th isothrm constant. Equilibrium uptak, q (mg/g) Tim (min) 5 ppm 1 ppm ppm 3 ppm 4 ppm 5 ppm Fig. 4. Effct of contact tim and initial concntration on th adsorption of CR on Langmuir isothrm [14] rfrs to homognous adsorption, which adsorption can only occur at a fixd numbr of dfinit localizd sits, with no transmigration of th adsorbat in th plan of th surfac. Th Langmuir modl can b givn as C 1 1 = + C (3) q q K q max L max whr q is th amount of adsorbat in th adsorbnt at quilibrium (mg/g), C is th quilibrium concntration (mg/l), and q max (mg/g) and K L ar th Langmuir isothrm constants rlatd to fr nrgy. Th abov quation can b linarizd to gt th maximum capacity, q max by plotting a graph of C /q vs. C. Th linar form of th Frundlich isothrm [15] modl is drivd assuming a htrognous surfac of adsorption capacity and adsorption intnsity with a non-uniform distribution of hat of adsorption. Th Frundlich modl can b givn as: F 1/ 2 q = K C (4) Rarranging q. 3, 1 log q = log K F + logc (5) n whr K F and 1/n ar Frundlich isothrm constant (mg/g) (dm 3 /g) n rlatd to adsorption capacity. A plot of log q vs log C yilds a straight lin, with a slop of 1/n and intrcpt of ln K F. Th Langmuir and Frundlich isothrm paramtrs along with thir rgrssion cofficints for MB and CR ar listd in Tabls 1. Tabls 1 show that th Langmuir isothrms appar to fit th xprimntal data of MB bttr than th Frundlich isothrms, as rflctd by corrlation cofficints ( ). This indicats that th adsorption of MB on and is homognous distribution of activ sits in adsorption affinity. As shown in rsults (Tabl 1), th was prformd bttr than for rmoving MB. Estrification brings ngativ charg of ion which is diffrnt with positiv ion carrid by mtyhln blu. This condition has lad to th dcrasing in rmoval dy of MB du to th incrasing rpulsiv forc btwn surfac functional group of papaya sd and MB that mainly xists was a cation form. Adsorption on CR on shows that both Frundlich and Langmuir isothrms was fit to th xprimntal data. Physical intractions can b considrd as th most ffctiv in MB adsorption. Bsids th physical intractions, som of MB ions would b adsorbd via ion-xchang. Frundlich isothrm fit th xprimntal data of CR for and bttr than Langmuir isothrms. It shows that th Frundlich isothrm can b usd for non-idal sorption that involvs htrognous surfac nrgy systms. Th htrognity is causd by prsnc of diffrnt functional 52

4 group on th surfac, and also by various mchanism of adsorbnt-adsorbat intraction. As a rsult, it is allowing multi-layr adsorption. Th largr valu of K F indicats th highr valu of adsorption. Th mor htrognous th surfac will bring th 1/n valu closr to zro [16]. Th magnitud of th xponnt n givs indication of th favorability and K F th capacity of th adsorbnt or adsorbat systm. D. Kintic Study Th kintic adsorption data wr procssd to study th dynamics of th adsorption procss in xprssions of th ordr of rat constant. Th spcific rat constants, k 1, for th adsorption of MB and CR on and wr commonly obtaind psudo-first and psudo-scond-ordr kintic modls Kintic data wr analyzd with th psudo-scondordr kintic modls. Th psudo-scond-ordr kintic can b prsntd by quation: t q t 1 1 = + t (6) 2 k q q 2 q Th linar plots of t/qt vrsus t (Figur not shown) xprimntal data ar fit with th psudo scond-ordrkintic modl for th both cationic and anionic dys. Th valus for psudo scond- ordr modl wr.98, which is highr than th valus obtaind for th psudo-first-ordr modl. Th calculatd q and k 2 for all cass ar rprsntd in Tabl 2. From th Tabl 2 and Tabl 3, it shows that th xprimntal data and th corrlation cofficints for th scond-ordr kintic modl ar bttr rprsntd th adsorption kintics, suggsting that th adsorption procss was controlld by chmisorption [18, 19] TABLE III. PSEUDO-SECOND-ORDER KINETIC PARAMETERS FOR REMOVAL OF MB BY AND AT 3 C C o (mg/g) q K 2 q K IV. CONCLUSIONS Prsnt studis shows that th chmical modification strification of carboxyl group could incrasd th prformanc adsorption capacity of papaya sd in rmoval cationic dy from aquous solution compard to anionic dy. It shows that carboxyl group was major functional group in cationic dy. Th adsorption isothrm data for MB wr bst fittd to th Langmuir isothrm and th maximum monolayr adsorption capacity was found to b 25. mg/g and. mg/g at 3 C for and rspctivly. Manwhil for CR, th bst fit isothrm modl was Frundlich isothrm. Th adsorption kintics can b prdictd by th psudoscond ordr modl. Th rsults would b usful for th dsigning of wastwatr tratmnt plants for th rmoval of various typs of dy spcially cationic dys. Sinc th raw matrial papaya sd abundantly in larg quantitis th tratmnt mthod sms to b conomical. TABLE I. Isothrm Langmuir Frundlich ISOTHERM CONSTANTS FOR THE ADSORPTION OF MB AND CR BY AND Paramtr q max K L K F n CR MB TABLE II. PSEUDO-SECOND-ORDER KINETIC PARAMETERS FOR REMOVAL OF CR BY AND AT 3 C C o (mg/g) q K 2 q K ACKNOWLEDGMENT Th authors acknowldg th rsarch grant providd by Univrsiti Tknologi Mara undr th Rsarch Managmnt Institut (RMI) Schm. (Projct: -RMI/ST/FRGS 5/3/Fst (129/1). REFERENCES [1] V.K. Garg, R. Gupta, A.Yadav, R. Kumar, Dy rmoval from aquous solution by adsorption on tratd sawdust, Biorsour. Tchnol., vol. 89, 3, pp [2] T. Robinson, G. McMullan, R. Marchant, P. Nigam, Rmdiation of dys in txtils fflunt: a critical rviw on currnt tratmnt tchnologis with a proposd altrnativ, Birsour. Tchnol., vol. 77, 1, pp [3] M. Rafatullah, O. Sulaiman, R. Hashim, A. Ahmad, Adsorption on mthyhln blu on low cost adsorbnt : A rviw, J.Hazard. Mtr., vol. 177, 1, pp.7 8. [4] I.M. Banat, P. Nigam, D. Singh, R. Marchant, Microbial dcolourization of txtil-dy-containing fflunts: a rviw, Biorsour. Tchnol., vol. 58, 1996, pp [5] I.D. Mall, V.C. Srivastava, N.R. Agarwa, I.M. Mishra, Rmoval of congo rd from aquous solution by bagass fly ash and activatd carbon: kintic study and quilibrium isothrm analyss, Chmosphr vol. 61, 5, pp

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