Removal of Copper from Water by Adsorption onto Banana Peel as Bioadsorbent

Transcription

1 Int. J. of GEOMATE, Jun, Int. J., of GEOMATE, Vol., No. Jun, (Sl., No. ), Vol. pp., 7-3 No. (Sl. No. ), pp. 7-3 Gotc., Const. Mat. and Env., ISSN:86-98(P), 86-99(O), Japan Rmoval of Coppr from Watr by Adsorption onto Banana Pl as Bioadsorbnt M. A. Hossain, H. Hao Ngo, W. S. Guo and T. V. Nguyn School of Civil and Environmntal Enginring, Univrsity of Tchnology Sydny, Australia ABSTRACT: Banana pl, a fruit wast wr usd to produc bioadsorbnt through nvironmnt frindly procss. It wr cut, washd, drid, groundd into powdr and usd for coppr rmoval. Coppr adsorption onto banana pl was dpndd upon th controlling paramtrs such as particl siz, doss, ph, contact tim, agitation spd and tmpratur. Slightly acidic watr (ph = 6) was found to b suitabl for coppr rmoval. Equilibrium data wr wll fittd (R =.998) with th Langmuir and Frundlich isothrms. Th monolayr adsorption capacity was 7.78 mg/g. Th calculatd R L and n valus has provd th favorability of coppr adsorption onto banana pl. Coppr adsorption was followd th scond ordr kintic proprly rathr than othr modls. Th quilibrium adsorption capacity was.39, 8.89, 8.8, 3.5 and 7.9 mg/g whn initial coppr concntrations wr, 5,,, and mg/l rspctivly. Solvnt.N Sulphuric acid showd highr dsorption of coppr (9%) and adsorption-dsorption procss can b continud till svn cycls fficintly. Kywords: Banana pl, Adsorption, Biosorbnts, Isothrm modls. INTRODUCTION Eco-toxicity on living organism has bcom a prim concrn from th last fw dcads. Massiv urbanization ar continuously rlasing wast and wastwatr to th cosystm and, causing pollution to nvironmnt and vntually toxicity to living bing. Th industrial fflunts which contain diffrnt drivativs of havy mtals such as Cd, Pb, Ni, Cr, As, Cu, F tc. ar continuously discharging to th cosystm and producing a significant toxic impact on aquatic nvironmnt. Among th havy mtals, coppr is th major availabl typ of havy mtal in th aquatic nvironmnt. Coppr in th blood systm may gnrat ractiv fr oxygn spcis and damag th protin, lipids and DNA []. Th xcss coppr compound in th body may also affcts on aging, schizophrnia, mntal illnss, Indian childhood cirrhosis, Wilson s and Alzhimr s disass [-]. Coppr has damagd th marin cosystm and damagd th gills, livr, kidnys, th nrvous systm and changing sxual lif of fishs [5-6]. Rcnt awarnss of toxicity originatd from watr and wastwatr ar attnding th intrst for nvironmntal scintist and rsarchr. Th sustainabl rmoval of havy mtals from watr and wastwatr has bcom a major challng for scintists. Bsids th availabl mthods for coppr rmoval, bio-tchnological rmoval ar shown som advantags as thy ar chap, radily availabl, low cost, simplicity to us and nvironmnt frindlinss. Hug and abandond agro-wasts may b th potntial sourcs for producing bioadsorbnts bsids th high cost adsorbnts for havy mtals rmoval. Diffrnt bioadsorbnts ar dvlopd from agro-wasts and usd for havy mtals rmoval such as ric straw [7], sawd [8], wood and bark [9], ta-wast [], maiz corn cob, jatropha oil cak, sugarcan bagass [], tamarind hull [], sawdust [3], ric husk [], saltbush [5], marin algal biomass [6], oliv pomac [7], activatd sludg [8], sugar bt pulp [9], wool, oliv cak, sawdust, pin ndls, almond shlls, cactus lavs, and charcoal [], safood procssing wast sludg [] and pin bark []. Bioadsorbnts which producd from agro-wasts may act as a significant matrial for coppr adsorption. Banana pl, an agro wasts is discardd all ovr th world as uslss matrial. It is causing wast managmnt problms though it has som compost, cosmtics and adsorbnt potntiality. It is an abandond, radily availabl, low cost and chap, nvironmnt frindly bio-matrial. Considring th abov critria, banana pl was slctd to prpar th biosorbnt. A stp was takn for prparing biosorbnt and usd for rmoval of coppr from watr. Th main aim of this rsarch was to dtrmin th potntiality and adsorption capacity of banana pl as bioadsorbnt.. MATERIALS AND METHODS. Matrials Th stock solution of coppr ( mg/l) was prpard by dissolving 3.99 g of coppr sulphat (CuSO.5HO) in L of milli-q watr and usd for all xprimnts with rquird dilution. Th banana pl wr collctd from kitchn and usd for whol xprimnts.. Mthods.. Prparation of adsorbnt Th collctd banana pl wr cut into small pics (< 5 mm), washd thr tims with tap watr and thr tims with distilld watr to rmov xtrnal dirt. Th wttd banana pl wr kpt in air for rmoving th watr from th surfac and drid in ovn at 5 C for hours. Th drid banana pl wr groundd into powdr and kpt in an air tid bottl for xprimntal uss... Study of adsorbnt doss Th ffct of adsorbnt doss on th quilibrium adsorption of coppr was invstigatd with banana pl of.5,.,.,.5,,, 5 and g in fiv st of ml watr which containd,.5, 5, and 5 mg/l of coppr concntration ach. Th Erlnmyrs wr shakn for hours with rpm at room tmpratur. Th watr sampls wr thn filtrd and analyzd in trms of Cu by AAS...3 Study of ph Th ffct of ph for coppr adsorption onto banana pl was invstigatd with.5g of banana pl in ml watr containing mg/l of coppr and ach sampl wr adjustd 7

2 Int. J. of GEOMATE, Jun,, Vol., No. (Sl. No. ), pp. 7-3 to ph btwn.8 to 3.5 using ithr N H SO or NaOH solution. Th Erlnmyrs wr shakn for hours with rpm at room tmpratur... Study of particl sizs Th groundd banana pl wr gradd with standard sivs to six particls sizs of 6,, 3, 5, 75 and < 75 µm. Banana pl (.5g) from ach gradd sizs wr addd to six Erlnmyr with ml watr containing mg/l coppr concntration and shakn for hrs at rpm...5 Study of tmpratur, contact tim and shaking spd Th ffct of tmpratur, contact tim and shaking spd (rpm) on adsorption of coppr wr xamind with diffrnt tmpratur (3-7 C), tim (3h) and spd (3- rpm) for mg/l coppr concntration with.5 g banana pl in ml watr...6 Equilibrium study Equilibrium adsorption xprimnts (triplicat) wr conductd with 6 Erlnmyr of ml watr containing to 5 mg/l of coppr concntration. Groundd banana pl of.5,. and.5 g wr addd in ach sts of xprimnts and shakn for hours with rpm at room tmpratur without ph adjustmnt. Th quilibrium data wr fittd with Langmuir, Frundlich and Tmkin isothrm modls...7 Kintics study Kintics xprimnts wr conductd with, 5, and mg/l coppr concntration in L watr and with 5 g of banana pl at room tmpratur ( o C) without ph adjustmnt. Watr was agitatd at rpm for hours. At diffrnt intrvals 5ml of watr sampls wr withdrawn and filtrd for analysis. Th kintics data wr valuatd with psudo-first-ordr, psudo-scond-ordr, Elovich and Richnbrg kintics quation...8 Dsorption study Dsorption of banana pl was studid using 8 typs of solvnt mdium including tap watr, milli-q watr, distilld watr,.n H SO,.N HCl,.N HNO 3,.N NaOH and. N CH 3 COOH. For this purpos,.5 g of saturatd (with Cu) banana pl was takn in ml of abov mntiond mdium and shakn at rpm for hr..3 Analysis Th collctd watr sampls from diffrnt xprimnts wr filtrd with filtr papr (Whatmann 5) and prpard for AAS analysis. Th sampls wr analyzd in trm of Cu by Atomic Absorption Spctromtr (AAS 93 plus, GBC, Australia). Th ph was masurd by Hanna HI 95 (HANNA Instrumnt, Romania) ph mtr.. Calculation Th amount of coppr adsorbd by adsorbnt (q) in th adsorption systms wr calculatd by th following mass balanc quation: V.(Ci C ) q () m and th prcnt rmoval (%) of coppr was calculatd using th following quation: (Ci C) %rmoval () Ci whr, V is th volum of solution (l), m is th amount of adsorbnt (g), and C i and C (mg/l) ar th initial and quilibrium mtal concntrations in th watr, rspctivly. Th prcnt dviation was calculatd as follows: (q.xp q.cal) (3) %dviation q.cal whr, q.xp and q.cal ar xprimntal and calculatd valus of amount of coppr adsorption onto banana pl. 3. RESULTS AND DISCUSSION 3. Environmnt frindly prparation Th prparation mthods ar th ky factor for any typ of bioadsorbnt, bcaus morphological proprtis such as particl siz and shap, binding surfac ara, and ovrall rmoval capacity dpnd on it. Simpl, asy to prpar and us, hazard fr and nvironmnt frindly tratmnts ar th rquirmnt for sustainabl prparation of bioadsorbnt. Considring th abov this rsarch is usd simpl and non-tratd prparation mthods rathr than th xpnsiv and high-tch pyrolysis and non-nvironmnt frindly acid/bas pr-tratmnt mthods [7-]. This is th novlty of this study. Th SEM micrograph (Fig.) rvald that microporous structurs, htrognous, rough surfac with cratr-lik pors wr xistd in banana pl. Th lctron micrographs also rvald that th particls ar of irrgular shap and its surfac xhibits a micro-rough txtur, which can promot th adhrnc of coppr. Fig. SEM micrograph ( k) of banana pl 3. Effct of doss Th ffct of doss was invstigatd with fiv coppr concntration-sts (-5 mg/l) in ml watr by adding ight doss for ach st (Fig.). Th prcnt rmoval of coppr was found to incras with an incras in th mass of adsorbnt. Highst coppr rmovals wr 85 and 88 % for th initial coppr concntration of 5 and mg/l, rspctivly at th adsorbnt dos of 5 g/l. Thraftr, th rmoval of coppr startd to dclin with incrasing in mass of adsorbnt for all fiv sts and thn rmaind lvld. Th partial aggrgation among th availabl activ binding sits may acts for lss rmoval of coppr at high doss [3]. Also, du to lack of activ binding sit, th lowr rmovals wr obtaind at low adsorbnt doss []. Thus, 5g (.5 8

3 Int. J. of GEOMATE, Jun,, Vol., No. (Sl. No. ), pp. 7-3 g/ml) of banana pl and mg/l of coppr concntration wr chosn to us for othr xprimnts. %rmoval of coppr q (mg/l) Cu: mg/l Cu:.5 mg/l Cu: 5 mg/l Cu: mg/l Cu: 5 mg/l 6 8 Adsorbnt doss g/l Fig. Effct of adsorbnt doss on rmoval of coppr (t: h; rpm: ; ph: 6-6.5; T: C) 3.3 Effct of ph ph is a controlling factor for any kind of mtal adsorption procss from aquous solution. Th surfac proprtis of adsorbnts, ionic stat of functional groups and spcis of mtals ar dpndnt on ph condition. ph dpndnt xprimnts wr conductd and th rsult ar shown in Fig.3. Th coppr adsorption was found to incras with an incras in ph from to 6 and attaind a maximum valu (.76 mg/g) at ph 6 (which was slightly acidic). Lattr th coppr adsorption capacity was dclind. Th spciation diagram [5] has confirmd that Cu + is th dominant fr spcis blow ph 6 which involvd in tru adsorption. Th H 3 O + ions compt with Cu + for binding on adsorbnt sits and it may b rsponsibl for lowr adsorption capacity at low ph [, 6]. At highr ph, th rmoval was also low compard to th optimum condition. This can b xplaind as th binding sit may not activat in basic condition [7]. Abov ph 6, th coppr startd prcipitating as Cu(OH) +, thrfor th rmoval was not compltly by adsorption [5, 6]. 6 8 ph Fig.3 Effct of ph of coppr adsorption (t: h; C o : mg/l; d: 5 g/l; rpm: ; T: C) 3. Effct of particls sizs of adsorbnt % rmoval 6µm µm 3µm 5µm 75µm <75µm Particl Sizs Fig. Effct of particl siz on rmoval of coppr (t: h; C o : mg/l; d: 5 g/l; rpm: ; T: C; ph: 6-6.5) Batch xprimnts for th ffcts of particls on adsorption wr conductd for six particl sizs (6µm to <75 µm) at room tmpratur and ph of (without adjustmnt). Fig. indicats that th rmoval of coppr was incrasd by dcrasing th particl sizs. Th prcnt rmoval of coppr incrasd from 7 to 96% whn dcrasing particl sizs from 6µm to <75µm. This bhavior can b attributd to th ffctiv surfac ara incrasd as th particl siz dcrasd and as a consqunc, th coppr adsorption incrasd [8]. 3.5 Effct of contact tim Exprimnts for contact tim wr conductd with fiv initial coppr concntrations (C o :,, 5, and mg/l) with a dos of 5 g/l banana pl at rpm and room tmpratur for hours. Fig.5 shows th ffct of contact tim on adsorption of coppr ions by banana pl. Adsorption rat of coppr on banana pl was found to b rlativly much fastr than thos rportd for som othr bio-adsorbnts []. Th rat of coppr rmoval was vry rapid during th first 3 min, and thraftr, th rat of coppr rmoval rmaind constant. Thr was no significant incras in adsorption aftr about 6 min. Th xprimnt with high C o showd th highr amount of coppr rmoval. Th coppr ion adsorption on banana pl was rachd at quilibrium aftr h. Initially, thr wr larg numbr of vacant activ binding sits in banana pl and consquntly larg amount of coppr ions wr bound rapidly onto banana pl. Th binding sit was shortly bcom limitd and th rmaining vacant surfac sits ar difficult to b occupid by coppr ions du to th formation of rpulsiv forcs btwn th coppr on th solid surfac and th liquid phas [9-3]. Bsids, th mso-pors bcom saturatd at th initial stag of adsorption whr th mtal ions ar adsorbd. As a rsult, th driving forc of mass transfr btwn liquid and solid phas in an aquous adsorption systm dcrass with tim laps. Furthr, th mtal ions hav to pass through th dpr surfac of th pors for binding and ncountr much largr rsistanc which slowing down th adsorption during th latr phas of adsorption [9]. q (mg/g) Co: mg/l Co: mg/l Co: 5 mg/l Co: mg/l Co: mg/l 5 5 Contact tim (mins) Fig.5 Effct of contact tim on rmoval of coppr (C o : mg/l; d: 5 g/l; rpm: ; T: C; ph: 6-6.5) 3.6 Effct of shaking spd Th ffct of shaking spd on adsorption of coppr was studid ovr th rang of 3- rpm for h with ml watr containing mg/l coppr and.5 g of banana pl. Fig.6 indicats that th prcnt adsorption incrasd with an incrasd of shaking spd and obtaind a maximum 88% adsorption at nar rpm. This shaking spd was mployd for othr xprimnt. At low and high spds, th coppr rmoval was lowr than optimum. Low spd could not sprad th particls proprly in th watr for providing 9

4 Int. J. of GEOMATE, Jun,, Vol., No. (Sl. No. ), pp. 7-3 activ binding sits for adsorption of coppr. It is rsultd an accumulation of banana pl in th bottom of watr and burid th activ binding sits. On th othr hand, th high spd vigorously sprading th particls of banana pl in th watr and did not allow sufficint tim to bind with coppr ions [3]. 9 %rmoval of coppr Shaking spd (rv/min) Fig.6 Effct of shaking spd on rmoval of coppr (t: h; C o : mg/l; d: 5 g/l; T: C; ph: 6-6.5) 3.7 Thrmodynamics proprtis To dtrmin th thrmodynamic proprtis and thrmal ffcts on th adsorption, th tmpratur variation xprimnts wr conductd at 3,, 5 and 7 C, with an initial coppr concntration btwn - mg/l and.5g banana pl. Th xprimntal data show that th quilibrium adsorptions wr dcrasd with an incras of tmpratur (Tabl). It sms to b that highr tmpratur has ngativ impact on coppr adsorption. Th thrmodynamic paramtrs such as Gibbs fr nrgy (ΔG ), nthalpy chang (ΔH ), and ntropy chang (ΔS ) wr calculatd to valuat th natur of th adsorption procss. For a givn tmpratur, a phnomnon is considrd to b spontanous if th ΔG has a ngativ valu. Morovr, if ΔH is positiv, th procss is ndothrmic and if it is ngativ, th procss is xothrmic. Th magnitud of ΔG (kj/mol) was calculatd using th following quation: o G RTlnK () a whr, R is univrsal gas constant,.83 kj/mol K; T is absolut tmpratur ( K) and K a th adsorption quilibrium constant from Langmuir and Tmkin isothrm and ΔH (kj/mol) was calculatd by th following quation: o o o ΔH ΔG T S (5) A plot of G vrsus T was found to b linar (Fig.7) and th valus of H and S, wr calculatd from th slop and intrcpt of th plots. Th thrmodynamic paramtrs calculatd from both Langmuir and Tmkin isothrm ar shown in Tabl. Th ngativ valus of G for Langmuir isothrm hav confirmd th fasibility of procss and th spontanous natur of adsorption. Howvr, th positiv valus from Tmkin isothrm showd th opposit of natur of adsorption. Th valus of G wr dcrasd from to -.63kJ/mol for Langmuir isothrm and incrasd from.95 to.3 kj/mol for Tmkin isothrm as th tmpratur incrass from 3 to 7 C. Th valus of H and S calculatd from Fig.6, using Langmuir constant, K a and Tmkin constant K T ar givn as.57 kj/mol and -. kj/mol K and.kj/mol and -.3 J/mol K, rspctivly. Th positiv valu of H indicats that th adsorption raction was ndothrmic and strong affinity of th banana pl for coppr ions and suggsts som structural changs in coppr ions and banana pl fibr [3]. In addition, th ngativ valu of S (for both isothrms) also suggsts that th adsorption was nthalpy drivn and spontanous in natur [7]. y =.x -.3 R =.7677 Langmuir Isothrm - Tmkin Isothrm y =.579x -. R =.98 Gibs fr nrgy, G T ( K) Fig.7. Rlationship btwn Gibbs fr nrgy chang, G and tmpratur, T ( K) of adsorption raction Tabl Calculatd valus of thrmodynamic paramtrs for th quilibrium adsorption of coppr onto banana pl T q m ΔG ΔH ΔS ( C) (mg/g) (kj/mol) (kj/mol) (kj/mol K) Lang Tm Lang Tm Lang Tm * Lang : Langmuir ; Tm : Tmkin 3.8 Adsorption isothrms Adsorption isothrms dscrib th quilibrium rlationships btwn adsorbnt and adsorbat. Thr adsorption isothrms (6)-(8) wr usd to fit th quilibrium data namly, Langmuir [3], Frundlich [33] and Tmkin [3]. Its applicability was judgd with th corrlation cofficints (R ). Langmuir quation can b linarizd by th following form: (6) q bq mc q m whr, C is th quilibrium concntration in liquid phas (mg/l), q m is th monolayr adsorption capacity (mg/l) and b is th Langmuir constant rlatd to th fr adsorption nrgy (l/mg). /q Dos: 5 g/l Dos:.5 g/l Dos: g/l /C 6 8 Fig.8 Langmuir isothrm for coppr adsorption onto banana pl (C o : -5 mg/l; t: h; rpm: ; ph: 6-6.5; T: C). Frundlich quation can b linarizd by th following form: lnq lnk F lnc n (7) whr, K F is a constant indicativ of th adsorption capacity of th adsorbnt (mg/ g) and th constant /n indicats th intnsity of th adsorption. Th linarizd form of Tmkin isothrm is as follows: 3

5 Int. J. of GEOMATE, Jun,, Vol., No. (Sl. No. ), pp. 7-3 lnq q - B lnk T B lnc whr, B = RT/b T, K T (l/g) and b T (kj/mol) ar th Tmkin constants. Th linar plot of Langmuir isothrm for coppr adsorption and th calculatd paramtrs along with rgrssion cofficints ar shown in Fig.8 and Tabl, rspctivly. Maximum adsorption capacity, q m, for complt monolayr covrag ar found 5, 35.7 and 8.57 mg/g for.5, and 5 g/l doss, rspctivly. R valus approaching to on, clarly suggst that Langmuir isothrm follows a good rlation of coppr adsorption with banana pl. Th adsorption capacity for banana pl was found highr than th prviously rportd mthods of mtal adsorption [7]. b is th adsorption constant rlatd to th affinity of binding sits(l/g) and lowr valu of b (.36,.9 and. l/g for thr doss) indicat that th particls radius of banana pl wr small toward adsorption [3]. Sparation factor (R L ), an ssntial charactristic of Langmuir isothrm modl was calculatd as th following quation: R L = /( + bc i ) (9) whr, C i is th initial concntration of mtal ions. Th valus of R L (.9-.7) rvald that coppr adsorption on banana pl is favourabl as th valus lis btwn and [3]. 6 Dos: 5 g/l Dos:.5 g/l Dos: g/l lnc Fig.9 Frundlich isothrm for coppr adsorption onto banana pl (C o : -5 mg/l; t: h; rpm: ; ph: 6-6.5; T: C) Th linar plot of Frundlich quation for coppr adsorption and th calculatd paramtrs ar shown in Fig.9 and Tabl, rspctivly. Th Frundlich isothrm modl was found bst fittd with xprimntal data as its poss highr R valu (.99,.98 and.989). K F is a Frundlich constant that shows adsorption capacity on htrognous sits with non-uniform distribution of nrgy lvl and n shows th intnsity btwn adsorbat and adsorbnt. Th calculatd valus of n (Tabl ) prov that th adsorption of coppr onto banana pl is favourabl as th magnitud lis btwn and 3 [3]. q (mg/g) Dos: 5 g/l Dos:.5 g/l Dos: g/l lnc Fig. Tmkin isothrm for coppr adsorption onto banana pl (C o : -5 mg/l; t: h; rpm: ; ph: 6-6.5; T: C) (8) Fig. and Tabl shows Tmkin isothrm and calculatd constant rlatd to hat of adsorption (b T ). Its wr.83,.8 and.7 kj/ mol for coppr adsorption on banana pl for th doss of.5, and 5 g/l rspctivly. Th lowr valus of b T (<8) indicat that th intraction btwn mtal and banana pl was wak. Th adsorption procss of coppr onto banana pl can b xprssd as physiosorption as indicatd by th valu of b T. Tabl Langmuir, Frundlich and Tmkin isothrm paramtrs and corrlation cofficints for th adsorption of coppr onto banana pl at diffrnt adsorbnt doss. Doss Langmuir Frundlich Tmkin q m b R K F n R b T K T R (g/l) (mg/g) (l/mg) (mg/g) (kj/mol) (l/mg) Adsorption kintics Kintic studis ar significant for any kind of biosorption procsss. Adsorption kintics not only dscribs th adsorption mchanism of mtals on adsorbnts but also dscrib th mtal adsorption rat which controls th contact tim of mtals at th solid-liquid intrfac [35]. Th adsorption mchanism dpnds on th physical and chmical charactristics of adsorbnt and adsorbat, ph of mdium, tmpratur, contact tim and aids and mass transport procss [3]. Kintics studis wr conductd at non adjustd ph condition with four initial coppr concntrations. Th data wr fittd with diffrnt kintics quation namly First Ordr, Scond Ordr, Elovich and Richnbrg kintics modls Th psudo-first-ordr and psudo-scond-ordr kintics quation ln(q-qt) t (min) 5 Co: mg/l Co: 5 mg/l Co: mg/l Co: mg/l Fig. Linar plot of psudo-first-ordr quations for coppr adsorption onto banana pl Th linar form of psudo first-ordr kintic modl [] is as follows: ln(q qt ) lnq kadt () Th adsorption rat (k ad ) ar calculatd from linar rgrssion analysis from th slop of linar plot of xprimntal data (ln(q - q t ) vs t). Th linar plot of th xprimntal data and th calculatd paramtrs ar shown in Fig. and Tabl 3, rspctivly. Th xprimntal data is not wll fittd for psudo-first-ordr kintic quation as th R wr low. Th kintics data wr also analyzd by psudo-scond ordr quation and th linar form as [37]: t t () q k q q t 3

6 Int. J. of GEOMATE, Jun,, Vol., No. (Sl. No. ), pp. 7-3 whr, k is th constant of psudo-scond-ordr rat; q is th biosorption capacity at quilibrium; and q t is th biosorption capacity at tim t. If th initial adsorption rat, as h = q t /t whn t approach to, h, (mg/g min) [35], is: h kq () Tabl 3 Calculatd paramtrs of psudo-first-ordr and psudo-scond-ordr kintics Kintics Paramtrs 5 modls mg/l mg/l mg/l mg/l Psudo-first-ordr q.xp (mg/g) q.cal (mg/g) k ad (min - ) R Psudo-nd-ordr q.cal (mg/g) k (g/mg.min) h (mg/g.min) R t/qt (min.g/mg) Co: mg/l Co: 5 mg/l Co: mg/l Co: mg/l 5 t (min) 5 Fig. Linar plot of psudo-nd-ordr quation for coppr adsorption onto banana pl at various C o Th quilibrium adsorption capacity and th scond-ordr rat constant wr calculatd from th slop and th intrcpt of th plot t/q t against t. Th graphical intrprtation of th data for scond-ordr-kintic modl and calculatd paramtrs ar shown in Fig. and Tabl, rspctivly. A good fittd (R >.999) linar plots ar obtaind from xprimntal data (Tabl 3) whil th calculatd valus of q also agrd with th xprimntal valus. This finding rvald that th coppr adsorption onto banana pl follows th psudo-scond-ordr mchanism and th chmical adsorption procss controls th adsorption rat. It was found that quilibrium adsorption capacity (q ) incrasd with an incras in initial coppr ion concntration (C o ). Th adsorption capacity incrasd from.88 to 7.3 mg/g whn C o was incrasd from to mg/l. Th calculatd valus of quilibrium adsorption capacitis (q.cal ) wr wll agrd with th xprimntal valus (q.xp ) for th scond-ordr kintic modl and th lowr % dviation confirmd th procss (Tabl ). Th q incrasd with incrasing C o, whil th k dcrass and th h incrass with incrasing C o Th Elovich kintics Th simplifid and linarizd form of Elovich kintics modl [38] can b xprssd as: q t ln( α ) ln(t) (3) β β whr, α is th initial adsorption rat (mg/g.min) and β is th dsorption constant (g/mg). A plot of q t vrsus ln(t) yildd a linar rlationship with a slop of (/β) and an intrcpt of (/β) ln(αβ). Tabl Calculatd kintic paramtrs of Elovich quation for coppr adsorption onto banana pl at diffrnt C o Paramtr Elovich kintics modl C o q.xp q.cal α β R %dviation (mg/l) (mg/g) (mg/g) (mg/g.min) (g/mg) x x qt (mg/g) Co: mg/l Co: 5 mg/l Co: mg/l Co: mg/l ln(t) Fig.3 Linar plot of Elovich modl for coppr adsorption onto banana pl at various C o Th Elovich modl is usd to xplain th coppr adsorption mchanism onto banana pl. Th two paramtrs (α and β) wr calculatd from th slop and intrcpt of th linar plot of q t vs ln(t) (Fig.3) and tabulatd in Tabl. A good rang of R valus (.9 to.99) wr found xcpt whn initial coppr concntration was mg/l. Th calculatd valus of α and β (Tabl ) showd a gnral trnd of changs with an incras in th initial coppr concntration. Th valus of α incrasd from.863 to with incrasd C o ( to mg/l), suggsting that th procss was chmisorptions corrsponding to th htrognity in natur of activ sits [39]. On th othr hand, with incrasd of C o, th β-valus showd a rduction trnd (5.36 to.76 g/mg). Thus, /β (which is apparntly indicativ of th numbr of sits availabl for adsorption, as pr th scond assumption) showd a distinct incras with an incras in concntration, again rinforcing th occurrnc of chmisorptions [] Richnbrg quation Richnbrg [] statd that th radius of adsorbnt s particls (r) controls th ffctiv diffusion of xchanging ions and film diffusion in adsorption may b rducd from th linar fit: Bt 6 Q () π whr, Q is th ratio of adsorbd concntration at tim t and th maximum adsorption capacity of th adsorbnt (=q t /q m ), Bt =π Di/r and Di is th cofficint of ffctiv diffusion of ions xchanging insid th adsorbnt particls. Th valu of Bt can b calculatd mathmatically for ach valu of Q, using th following quation: Bt.977 ln( Q) (5) Th linar plot of Bt vrsus contact tim t is shown in Fig.. Th linar plot rvald that th data was not quit fittd with modl for h tim priod as produc low R valus (.96,.855,.93 and.9) for th initial coppr concntration of, 5, and mg/l, rspctivly. 3

7 Int. J. of GEOMATE, Jun,, Vol., No. (Sl. No. ), pp. 7-3 Howvr, it was linar btwn to 6 min with a highr R valus (>.98). Th rgrssion lins did not pass through th origin which indicatd that a thin film of coppr was formd on th surfac of banana pl. Bt Co: mg/l Co: 5 mg/l Co: mg/l Co: mg/l t (min) Fig. Linar plot of Richnbrg kintics quation for coppr adsorption onto banana pl 3. Dsorption prformanc %rcovry of coppr Tap watr Mill-Q watr Distilld watr. N. N HCl. N. N. N NaOH HSO HNO3CH3COOH Fig.5 Dsorption of coppr from banana pl (Co: mg/l; dsorption tim: h; rpm: ; T: C) Dsorption of mtals or rgnration of adsorbnts from usd-adsorbnts ar crucial to rpat th us of adsorbnts, rcovr of prcious mtals and rduc th cost of opration in any watr tratmnt systm. Th adsorbd mtals on adsorbnts can not b compltly rvrsibl as rportd by svral obsrvations on litratur [-]. Eight solvnt wr usd for dsorption/rgnration xprimnt and th rsults ar prsntd in Fig.5. Among th solvnts th tap watr, milli-q watr, distilld watr, CH 3 COOH and NaOH wr rsultd a limitd amount of coppr ion rcovry (<3%). Th highst (9%) rcovry was found with th us of.n H SO. Th othr two acids. N HCl and. N HNO 3 wr shown lowr fficincis (5 and 7%). In th dsorption systm H + rlasd from th acids which rplacd mtal cation (Cu + ) on th surfac of th banana pl []. Th rcovry and rus procsss for banana pl can b continud upto 7 tims with minor dviation in rmoval fficincy. 3 CONCLUSION Banana pl is a high capacitat, conomically viabl and low cost adsorbnt for coppr rmoval. Coppr adsorption onto banana pl follows a psudo scond ordr kintics. Adsorption of coppr on banana pl shows high association with Langmuir and Frundlich isothrm modl. Th g of banana pl can adsorb 8 mg of coppr in a favourabl condition. This study can conclud that banana pl is th favourabl altrnativ of coppr rmoval from watr. ACKNOWLEDGMENTS This rsarch was supportd by th Cntr for Tchnology in Watr and Wastwatr (CTWW), School of Civil and Environmntal Enginring, Univrsity of Tchnology, Sydny (UTS) and UTS Intrnational Postgraduat Rsarch Scholarship. 6 REFERENCES [] Brwr GJ, Coppr toxicity in th gnral population. Clin. Nurophysiol., vol.,, pp [] Brwr GJ, Iron and coppr toxicity in disass of aging, particularly athrosclrosis and Alzhimr's disas, Exp. Biol. Md., vol. 3, 7, pp [3] Fallr P, Coppr and zinc binding to amyloid-bta: coordination, dynamics, aggrgation, ractivity and mtal-ion transfr, Chmbiochm., vol., 9, pp [] Haurau C, and Fallr P, Abta-mdiatd ROS production by Cu ions: structural insights, mchanisms and rlvanc to Alzhimr's disas, Biochimi., vol. 9, 9, pp. -7. [5] Van Gndrn EJ, Ryan AC, Tomasso JR and Klain SJ, Evaluation of acut coppr toxicity to larval fathad minnows (Pimphals promlas) in soft surfac watrs, Environ. Toxicol. Chm., vol., 5, pp. 8-. [6] Flmming CA and Trvors JT, Coppr toxicity and chmistry in th nvironmnt: a rviw, Watr, Air, & Soil Pollution., vol., 989, pp [7] Gao H, Liu Y, Zng G, Xu W, Li T and Xia W, Charactrization of Cr(VI) rmoval from aquous solutions by a surplus agricultural wast-ric straw, J. Hazard. Matr., vol.5, 8, pp.6-5. [8] Basha S, Murthy ZVP and Jha B, Biosorption of hxavalnt chromium by chmically modifid sawd, Cystosira indica, Chm. Eng. J., vol.37, 8, pp [9] Mohan D, Pittman Jr. CU, Bricka M, Smith F, Yancy B, Muhammad J, Stl PH, Alxandr-Franco MF, Gomz-Srrano V and Gong H, Sorption of arsnic, cadmium, and lad by chars producd from fast pyrolysis of wood and bark during bio-oil production, J. Colloid Intrfac Sci., vol.3, 7, pp [] Malkoc E and Nuhoglu Y, Potntial of ta factory wast for chromium(vi) rmoval from aquous solutions: Thrmodynamic and kintic studis, Sp. Purif. Tchnol., vol.5, 7, pp [] Garg UK, Kaur MP, Garg VK and Suda D, Rmoval of hxavalnt chromium from aquous solution by agricultural wast biomass, J. Hazard. Matr., vol., 7, pp [] Vrma A, Chakraborty S and Basu JK, Adsorption study of hxavalnt chromium using tamarind hull-basd adsorbnts. Sp. Purif. Tchnol., vol.5, 6, pp [3] Mmon SQ, Bhangr MI and Khuhawar MY, Prconcntration and sparation of Cr(III) and Cr(VI) usingsawdust as a sorbnt, Anal. Bioanal. Chm., vol. 383, 5, pp [] Kumar U and Bandyopadhyay M, Fixd bd column study for Cd(II) rmoval from wastwatr using tratd ric husk, J. Haza. Matrials, vol.9, 6, pp

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Soil Sci., vol.39, 988, pp [3] Farrah H and Pickring WF, Extraction of havy mtal ions sorbd on clays, Watr Air Soil Pollut., vol. 9, 978, pp [] Ainsworth CC, Pilon JL, Gassman PL and Van Dr Sluys WG, Cobalt, cadmium, and lad sorption to hydrous iron oxid: rsidnc tim ffct, Soil Sci. Soc. Am. J., vol.58, 99, pp Intrnational Journal of GEOMATE, Jun,, Vol., No. (Sl. No. ), pp. 7-3 MS No.3c rcivd January,, and rviwd undr GEOMATE publication policis. Copyright, Intrnational Journal of GEOMATE. All rights rsrvd, including th making of copis unlss prmission is obtaind from th copyright propritors. Prtinnt discussion including authors closur, if any, will b publishd in th Jun 3 if th discussion is rcivd by Dc.. Corrsponding Author: M. A. Hossain 3