JMES, 2017 Volume 8, Issue 3, Page ICMES2016, 1-3 Dec. 2016, Oujda

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1 Journal of Marials and Environmnal Scincs ISSN: Copyrigh 07, Univrsiy of Mohammd Prmir Oujda Morocco JMES, 07 Volum 8, Issu 3, Pag hp:// ICMES06, -3 Dc. 06, Oujda Dcolourizaion of Caionic and Anionic Dys from Aquous Soluion by Adsorpion on NaOH Trad Eggshlls: Bach and Fixd Bd Column Sudy using Rspons Surfac Mhodology S. Akazdam, M. Chafi, W. Yassin, L. Sbbahi, B. Gourich, N. Barka. Laboraory of Enginring, Procsss and Environmn (LEPE) High School of Tchnology, Univrsiy Hassan II of Casablanca Morocco.. Univrsiy Hassan, Laboraoir ds Scincs ds Maériaux, ds Miliux d la Modélisaion (LS3M), BP.45, 5000 Khouribga, Morocco. Rcivd 0 Nov 06, Rvisd 5 Jan 07, Accpd 9Jan 07, Kywords Biosorpion ; Dy,Rmoval; Kinics, Isohrms; Thrmodynamics; Bddph; Fixd-bdcolumn; Waswar, TES, RSM,BBD, Opimisaion, modling ; S.AKAZDAM said.akazdam@gmail.com Absrac In his sudy, w invsigad h adsorpion of Mhyln blu (MB) and Acid Orang 7 (AO7) dys on a naural adsorbn, w hav slcd a food drivaiv produc (ggshlls) rad wih NaOH (TES) as a nw and ponial biosorbn. Diffrn modls of adsorpion isohrms in bach sudy wr applid o fi xprimnal quilibrium daa a diffrn soluion mpraurs; Langmuir and Tmkin modl fid h adsorpion daa qui rasonably (R > 0.98). Rsuls hav showd ha h adsorpion of MB on TES dy followd vry wll h scond ordr kinic modl. Th hrmodynamic paramrs wr valuad; h ngaiv valus of ΔH and ΔG indicad rspcivly ha h adsorpion of MB ono TES was xohrmic and sponanous procss. Th coninuous mhod was modld by rspons surfac mhodology (RSM). Th ffc of opraing paramrs such as flow ra, iniial dy concnraion, and bd high wr xploid in his sudy. Th prcision of h quaion obaind by Box Bhnkn dsign (BBD) uiliy for modling and opimizaion by rspons surfac mhodology RSM was confirmd by h analysis of varianc (ANOVA). Th opimum condiions proposd by Box Bhnkn dsign (BBD) o rach h maximum dy rmoval hrough adsorpion procss. Undr h opimum condiions, h rmoval fficincy ofao7 was 89.89%. In summary, h rsuls hav sablishd good ponialiy for h was ggshll paricls o b usd as a sorbn for h rmoval of MB from waswar in bach sudy and wr shown o b suiabl adsorbn for adsorpion of AO7 using fixd-bd adsorpion column.. Inroducion I is undniabl ha our plan suffrs from a problm ha is bcoming dangrous which is linkd o a possibl war shorag in h coming days. On h ohr hand, wih chnological advancs and populaion growh, war dmand has incrasd. Th dgr of polluion bcoms mor and mor pronouncd bcaus of ffluns and missions rlasd from diffrn indusris. Dys scors, prining and finishing of xils occupy a spcial plac bcaus hs aciviis gnra significan waswar polluion wih warning qualiaiv and quaniaiv amouns of svral yps of polluans ha may b acidic or basic dys in naur []. Dys ar on of h imporan classs of h polluans whos prsnc in war bodis is oxic o aquaic as wll as human livs, his is du o h prsnc of an aromaic srucur and, in som cass, mals in hir srucur. Th biodgradabiliy of his yp of polluion is gnrally difficul bcaus dys hav a synhic origin and a complx molcular srucur which maks hm mor sabl and difficul o b biodgradd []. Thr ar svral mhods ha can b classifid ino wo yps: physical and chmical procsss o ra war chargd wih dys, bu adsorpion is considrd now as on of h mos imporan sparaion chnologis insofar h adsorbn can b rgnrad in par or complly for h anohr us. Acivad carbon is h mos commonly usd adsorbn bu i is vry xpnsiv which imposs h nd for rgnraion; his is why h dvlopmn of adsorbn basd on naural producs and chapr provs a vry inrsing soluion, his chnology is rmd biosorpion [3]. Lo of non-convnional low cos adsorbn such as ric hull ash, sugarcan bagass, clay, durian shll, banana salk was and mango sd krnl powdr, sawdus, pin ndl, ucalypus bark, prawn shll acivad carbon, and mango sd krnl powdr hav bn usd for h rmoval of dys and havy mal ions from aquous soluion. In addiion o hir low cos, h us of bioadsorbn gnras svral ohr bnfis for xampl is cid: good adsorpion capaciy, slciv adsorpion of fflun, fr availabiliy, asy rgnraion and rquirs rlaivly simpl chnologis [4]. This sudy aims, among ohr hings, minimizaion of MBand AO7 in aquous soluion and o promo his abundan marial in our counry by rusing i from was of houss and rsaurans. Eggshll is composd chmically of: 94 o 97% calcium carbona; 3% o 6% proin; % of various minrals (including magnsium, JMES, 07, 8 (3), pp

2 poassium and rac amouns of iron, sulfur and phosphorus) [5]. To incras is adsorpion capaciy, h ggshlls wr chmically rad by NaOH, indd, his ramn is viwd as on of h widly usd chmical ramn chniqus for surfac modificaion of agriculural was for h purpos of improving is adsorpion propris such as srucural durabiliy, raciviy and naural ion-xchang capaciy [6]. Adsorpion in bach sudy and fixd-bd columns using acivad carbon has bn widly usd in indusrial procsss for h rmoval of conaminans from aquous xil indusry ffluns, sinc i dos no rquir h addiion of chmical compounds in h sparaion procss [7]. Adsorpion in a fixd bd column can b usd coninuously undr high fflun flow ras and i has bn usd in many polluion conrol procsss such as rmoval of ions by an adsorbn bd or rmoval of oxic organic compounds by carbon adsorpion [8]. In his sudy, h TES has bn sd for rmoval of aquous soluions. In applicaion of adsorpion procss on an indusrial scal, i is crucial o improv procss fficincy, rduc opraional cos and im o minimum and ak ino accoun h mos imporan facors, wha can b achivd by applying h opimizaion chniqus such as rspons surfac mhodology (RSM). Drmining h ffc of a singl facor on h fficincy of h procss is rlaivly simpl. I is dfinily mor of a challng o assss h ffc of svral paramrs a onc. Rspons surfac mhodology basd on xprimnal daa maks asir o plan h nir modling procss by rducing h numbr of xprimns o h ncssary minimum, and allows a mahmaical quaion o fi h xprimnal rsuls, which is rquird for h procss opimizaion [9]. In our sudy, w wr inrsd o h adsorpion procss of MB ono NaOH rad ggshll (TES). Th xprimnal par of his sudy was basd on modling h adsorpion kinic, h vrificaion of diffrn adsorpion isohrm and h simaion of hrmodynamic propris in bach sysms. In coninuous sysm, TES is usd o rmov azo dy (AO7) from aquous soluion hrough column sudis. Th objciv of his sudy was o invsiga h adsorpion ponial of AO7 ono TES fixd-bd. Th imporan dsign paramrs such as inl concnraion of dy soluion, fluid flow ra and column bd high [0] wr invsigad using a laboraory scal fixd-bd column. Th main ffcs and inracion ffcs bwn procss variabls on h dy adsorpions wr analyzd basd on h BBD. Thir maximum adsorpion capaciis hav bn opimizd using RSM mhod.. Marials and mhods.. Prparaion and Characrizaion of Eggshll Powdr Eggshll, wr collcd from houss and local rsaurans. To rmov impuriy and adhring dir, i wr firs washd svral ims in ap war, and hn boild in disilld war. Th washd marials wr hn drid a 00 C for 4 h in h dry ovn. Th drid ggshlls wr crushd and siv o rcovr h paricl siz powdrs bwn 0.50 and 0.7 mm. Finally, h sivd marial was rad wih sodium hydroxid NaOH N for hin a flask had wih rflux, hn h sampl was washd unil nuralizaion and drid in h ovn a 00 C for 4 h. To rmov moisur bfor ach us, w pu h rsuling adsorbn TES in a dryr.fourir Transform Infrard (FTIR) analysis was applid o drmin h surfac funcional groups, using FTIR spcrophoomr (SCO TECH SP-FTIR-). Th spcra wr rcordd from 4000 o400 cm - []... Adsorba Prparaion... Mhylnblu Mhyln blu is a dy having h mpirical formula C 6 H 8 N 3 S, λ (665nm) and a molcular mass M=39.86g/mol; h molcular srucur is rprsnd in Fig.. This organic dy is usd o s h adsorpion capaciy of adsorbns and masur hir surfac aras. A sock soluion was prpard by dissolving 0.5 g of dy in lir of disilld war, and o prpar h dsird concnraions ar don diluions []. -a- -b- Fig. : Molcular srucur of: -a- Mhyln blu. b- Acid Orang 7. JMES, 07, 8 (3), pp

3 ... Acid Orang 7 Th Acid Orang 7 dy also calld Acid Orang II (Sigma-Aldrich), blonging o h family of h anionic dys. AO7 is a dy having h mpirical formula C6HNNaO4S, molcular mass g/mol and λ (485nm). I is rprsnaiv of a xil yp of polluion. Is srucural formula is shown in Fig.. Sock soluions wr prpard by dissolving rquisi quaniy of dy wihou furhr purificaion in disilld war, and h concnraions usd wr obaind by diluion of h sock soluion. Th ph was adjusd o a givn valu by addiion of HCl (N) or NaOH (N) [3]..3.Biosorpion Isohrms Th bach adsorpion xprimns wr conducd in a s of 50 ml rlnmyr flask conaining adsorbn and 00 ml of MB soluion a various iniial concnraions. Th flasks wr agiad in an isohrmal war-bah shakr a 00 rpm and soluion mpraur was varid in h rang (5 35 C); All mixurs wr sudid unil h quilibrium is rachd. Afr dcanaion and cnrifugaion for 5min a 000r/min, h quilibrium concnraions of dy in h soluion wr masurd a 665 nm. Th ph of soluions was adjusd wih N Hcl or N NaOH soluions [4]..4. Biosorpion kinics Th main objciv of his kinic sudy is o s h influnc of svral paramrs on h law of spd conac im of h MB adsorpion procss on h TES such as mpraur, iniial dy concnraion using h bach chniqu. In a bach racor, w conacd a volum of 3L MB of soluions a diffrn concnraions ranging from 5 o 00 ppm wih a 3g TES mass mainaining a consan sirring spd and a dfini mpraur. A inrvals of dfini im, sampls wr akn, cnrifugd for masuring h rsidual concnraion by UVvisibl spcrophoomr a ƛ = 665 nm. Ths xprimns wr conducd a varying mpraurs valus (0, 5, 30 and 35 C). Th dy rmoval prcnag was calculad [5] from: (C0 - C) R (%) 00 x () C0 Whr C 0 is h iniial concnraion of dy in soluion (mg/l), and C is h final dy concnraion in aquous soluion afr phas sparaion (mg/l). Th amoun of biosorpion pr gram of TES a any im, q (mg/g), was valuad using [6]: v q = (C0 - C ) x () m Whr C 0 and C (mg/l) ar h liquid-phas concnraions of MB a iniial and any im rspcivly, v is h volum of h soluion (L) and m is h TES mass (g)..5. Isohrm Modling Th isohrmal curvs dscrib h rlaionship a h adsorpion quilibrium bwn adsorbd spci and an adsorbn amoun in a givn solvn a a consan mpraur. Th adsorpion isohrms wr prformd wih diffrn iniial concnraions in ordr o drmin h sorpion mchanisms, h surfac propris and affiniis of h sorbn and h adsorpion sauraion capaciy. A suiabl modl can b found by ploing solid phas concnraion agains liquid phas concnraion graphically [7].Svral modls wr analyzd such as Langmuir, Frundlich, Dubinin Radushkvich (D R), gnralizd isohrm and Tmkin isohrm. Linar rgrssion is frqunly usd o drmin h bs-fiing isohrm [8].Th horical Langmuir sorpion isohrm is valid for adsorpion of a solu from a liquid soluion as monolayr adsorpion on a surfac conaining a fini numbr of idnical sis. Th modl is basd on svral basic assumpions [9]:. Adsorpion is assumd o ak plac a spcific homognous sis wih h adsorbn;. Onc a dy molcul occupis a si; 3. Th adsorbn has a fini capaciy for h adsorba (a quilibrium); 4. All sis ar idnical and nrgically quivaln. Thrfor, h Langmuir isohrm modl was chosn for simaion of h maximum adsorpion capaciy corrsponding o compl monolayr covrag on h sorbn surfac. Th gnralizd non-linar form of h Langmuir isohrm is rprsnd by: q qmax K = K L L C C JMES, 07, 8 (3), pp (3)

4 Whr C (mg/l) is h concnraion of MB soluion a quilibrium; q (mg/g) is h corrsponding adsorpion capaciy; q max is h Langmuir isohrm consan (maximum adsorpion capaciy) (mg/g); K L is a consan rlad o h adsorpion nrgy (L/mg).Th linar quaion of Langmuir isohrm modl can b wrin as followd: C C = (4) q q K L q max max Th ssnial characrisic of h Langmuir isohrm can b xprssd by h dimnsionlss consan calld quilibrium paramr R L dfind by [0]: R L = (5) K L C0 Th sparaion facor R L valus indica h yp of isohrm o b irrvrsibl (R L = 0), favorabl (0< R L <), linar (R L =) or unfavorabl (R L >). Th Frundlich isohrm modl is h arlis known rlaionship dscribing h sorpion procss. Th modl applis o adsorpion on hrognous surfacs wih inracion bwn adsorbd molculs and h applicaion of h Frundlich quaion also suggss ha sorpion nrgy xponnially dcrass on complion of h sorpional cnrs of an adsorbn. This isohrm is an mpirical quaion ha can b mployd o dscrib hrognous sysms and is xprssd as []: /n q = K C (6) F Whr K F is h Frundlich consan rlad o h bonding nrgy. I can b dfind as h adsorpion or disribuion cofficin and rprsns h quaniy of dy adsorbd ono adsorbn for uni quilibrium concnraion. /n is h hrogniy facor and n paramr is a masur of h dviaion from linariy of adsorpion. Is valu indicas h dgr of non-linariy bwn soluion concnraion and adsorpion as follows: if n=, h adsorpion is linar; if h valu n<, his implis ha adsorpion procss is chmical; if h valu n>, adsorpion is a favorabl as physical procss. Convrsly, h valus of (/n < ) and (/n>) indica a normal Langmuir and coopraiv adsorpion, rspcivly. Equaion (6) can b linarizd in h logarihmic form (7) so ha h Frundlich consans can b drmind: log(q ) = log(k ) log(c n F (7) Tmkin isohrm modl conains a facor ha xplicily aks ino accoun adsorbing spcis adsorba inracions. This modl assums h following:. Th ha of adsorpion of all h molculs in h layr dcrass linarly wih covrag du o adsorba adsorba inracions.. Adsorpion is characrizd by a uniform disribuion of binding nrgis, up o som maximum binding nrgy. Th drivaion of h Tmkin isohrm assums ha h fall in h ha of sorpion is linar rahr han logarihmic, as implid in h Frundlich quaion. Th Tmkin isohrm has commonly bn applid in h following form [] : RT = ln( k C ) (8) b q Th Tmkin isohrm can b xprssd in is linar form as: q = Bln(k ) Bln(C ) (9) RT = b B (0) Whr T is h absolu mpraur in K and R is h univrsal gas consan 8.34 J/(mol. K). Th consan b is rlad o h ha of adsorpion. Th adsorpion daa wr analyzd according o h linar form of h Tmkin isohrm. Anohr quaion usd in h analysis of isohrms was proposd by Dubinin Radushkvich. D R modl was applid o sima h porosiy apparn fr nrgy and h characrisic of adsorpion. Th D R isohrm is no assuming a homognous surfac or consan sorpion ponial bu is common and linar forms can b [3]: JMES, 07, 8 (3), pp )

5 And q = Q xp (-K ) max () lnq = lnq m - K () Whr K is a consan rlad o h adsorpion nrgy, Q m h horical sauraion capaciy, ε is h Polanyi ponial. ε can b calculad from (3): = RT ln( ) (3) C Th plo's slop of ln(q ) vrsus ε givs h consan K (mol /(kj )) and h inrcp yilds o adsorpion capaciy, Q m (mg/g). K givs h man fr nrgy of adsorpion (E) pr molcul of h sorba whn i is ransfrrd o h surfac of h solid from infiniy in h soluion and can b compud using [4]: E = (4) k Th magniud of E is usful for simaing h yp of adsorpion procss. Adsorpion yp can b xplaind by chmical adsorpion if h magniud of E is 8 6 kj/mol. I's accpd ha whn h adsorpion nrgy is lowr han 8 kj/mol, h yp of adsorpion can b dfind as physical adsorpion. [5].6. Kinic Modls I is ncssary o idnify h yps of adsorpion mchanism in a givn sysm, hr ar svral kinic quaions availabl for analyzing xprimnal sorpion; h xprimnal modls sd in h prsn work ar Psudo-firs, Psudo-scond. Inraparicl diffusion, Elovich and Bangham's modls ar also vrifid for sudying h mchanism of diffusion..6.. Psudo-Firs-Ordr Modl Th adsorpion kinic daa wr dscribd by h Lagrgrn psudo-firs-ordr modl, which is h arlis known quaion dscribing h adsorpion ra basd on h adsorpion capaciy. Th Lagrgrn quaion is commonly xprsss as: dq d = K (q - q ) Whr q and q ar h adsorpion capaciy a quilibrium and a im, rspcivly (mg/g), k is h ra consan of psudo-firs ordr adsorpion (l/min). By ingraion, i is found ha [6]: ln(q - q ) = ln(q ) - k(t).6.. Psudo-Scond-Ordr Modl Th adsorpion kinic may b dscribd by h psudo-scond ordr modl, which is gnrally givn as in: dq d = k ) ()(q - q Whr k (g/mg.min) is h corrsponding ra consan of adsorpion. By ingraion, h las quaion simplifid and can b rarrangd and linarizd o obain h following rlaionship [7]: q = (k xq ) q Th scond-ordr ra consans is usd o calcula h iniial sorpion ra h (mg/g.min) givn by h (9) = k xq.6.3.elovich Modl Th Elovich quaion is on of h mos usful modls for dscribing chmisorpion, which is givn as [8]: dq d (5) (6) (7) = xp (- q ) (0) (8) JMES, 07, 8 (3), pp

6 Whr α rprsns h iniial adsorpion ra (mg/g.min) and β is rlad o h xn of surfac covrag and acivaion nrgy for chmisorpion (g/mg), hy can b compud from h slop and inrcp of h linar plo of q vrsus ln() as shown as h linar quaion of his modl: q = ln( ) ln( ) ().6.4. Inraparicl diffusion Modl Adsorpion is a muli-sp procss involving ranspor of h adsorba (dy) molculs from h aquous phas o h surfac of h solid paricls hn followd by diffusion of h solu molculs ino h por inriors. Th inraparicl diffusion is anohr kinic modl dvlopd by Wbr and Morris should b usd o sudy h ralimiing sp for MB adsorpion ono TES. If h xprimn is a bach sysm wih rapid sirring, hr is a possibiliy ha h ranspor of sorba from soluion ino pors of h adsorbn is h ra-conrolling sp. Th inra-paricl diffusion is commonly xprssd by [9]: / q = K () C () dif Whr K dif (mg/gmin / ) is h inraparicl diffusion ra consan and C (mg/g) givs an ida abou h hichnss of h boundary layr..6.5.bangham's Modl I is gnrally xprssd as [30]: C0 k0m log( ) = log( ) log( ) (3) C0 - q m.303 V Whr C 0 is h iniial concnraion of h adsorba in soluion (mg/l), V h volum of h soluion (ml), m h wigh of adsorbn usd pr lir of soluion (g/l), q (mg/g) h amoun of adsorba raind a im. α and k 0 ar h consans of h modl obaind by log[c 0 / (C 0 mq )] = f(log ) curvs..7. Adsorpion Thrmodynamics To invsiga h adsorpion procsss, h changs of hrmodynamic paramrs, such as, nropy ΔS, nhalpy ΔH and h Gibbs nrgy ΔG and acivaion nrgy E a for h sysm MB/TES mus b drmind. Thy can b calculad according o [3] : H S lnk d = - (4) K d = q C RT G -RT ln(k d ) R Whr T( C) is h absolu mpraur, R is h univrsal gas consan and K d (L/mol) is h disribuion cofficin. ΔH and ΔS can b rspcivly calculad from h slop and inrcp of h plo of ln(k d ) vrsus /T..8. Sorpion xprimns in fixd-bd chniqu.8.. Exprimnal Procdurs Th fixd bd xprimns wr carrid ou in a glass column of cm inrnal diamr, 30 cm of h lngh high and hr sampling poins a 5 cm inrvals. A known quaniy of h prpard acivad carbon TES was packd in h column o yild h dsird bd high of h adsorbn 50, 00 and 50 mm wih a layr of glass wool a h boom. Disilld war was passd hrough h column in ordr o rmov impuriis from h adsorbn. Thr flow ras (, 4 and 6 ml/min) wr pumpd o h op of h packd column by using prisalic pump wih diffrn iniial dy concnraions (5, 30, 50, 80 mg/l). Th sampls of AO7 soluions a h oul of h column wr akn a rgular im inrvals and h concnraion of dy was masurd using an UV visibl spcrophoomr a wavlngh of 485 nm. Fixd bd sudis wr rminad whn h column rachd xhausion [3]. Th xprimnal dail of fixd bd column usd in adsorpion sudy is givn in Tabl. Brifly, h xprimn was carrid ou by passing hrough column wih conrolld flow ra during xprimns. JMES, 07, 8 (3), pp (5) (6)

7 Tabl : Exprimnal dails for column adsorpion of ao7 ono TES SYSTEM Flow ra (ml/min) [AO7] (ppm) Bd high (cm) Flow ra, 4 and Iniial Concnraion 5 0, 30 and 50 5 Bd high , 0 and Rspons surfac mhodology Rspons surfac mhodology is an xprimnal chniqu usd for prdicing and modling complicad rlaion bwn indpndn facors and on or mor rsponss. In his sudy, rspons surfac mhodology was applid o opimiz h adsorpion of Acid orang 7 by TES. Exprimns wr prformd using Box Bhnkn dsign (BBD). Th scond-ordr polynomial quaion xndd wih addiional cubic ffcs was mployd as an objciv funcion. Th scond ordr modl is usually sufficin for h modling and opimizaion on h basis of dsigns, howvr hird ordr and highr ffcs ar somims imporan, spcially in ordr o achiv br fi and insignifican lack-of-fi. For insanc, Box Bhnkn dsign was crad o sima h scond-ordr modl, howvr hr may b siuaions in which non- random porion of his modl provids an inadqua rprsnaion of h ru man rspons, an indicaion of lack-of-fi of h scond- ordr modl. Thus, in his sudy som hird ordr modl rms wr addd o h scond ordr polynomial quaion. Accuracy of modl fiing was valuad by mans of ANOVA. All calculaions wr prformd in Sagraphics [33] Box Bhnkn dsign In his sudy, h BBD dsign mhodology was mployd o opimiz h opraional variabls and was usd o prdic impacs of rspciv paramrs on h adsorpion procss. Among many facors affcing h adsorpion procss, hr procss variabls, i.. iniial AO7 dy concnraion (X ), bd high (X ) and flow ra (X 3 ) wr slcd and wr considrd as indpndn variabls and h rmoval of dy (Y) as a rspons was dfind and modld. BBD conains s of 5 xprimn runs whos valus of ach facor wih hr lvls (low, mdium, high), bing is codd o sandard valus (-, 0,+) in h appropria rang and lvls of paramrs wr lisd in (Tabl ). Th scond-ordr polynomial rspons quaion was usd o prob h inracion bwn h dpndn and indpndn variabls. Th rmoval (%) of dy is slcd as h rspons for h combinaion of indpndn variabls, Subsqunly xprimnal daa was fid o h scond ordr polynomial modl xndd wih addiional cubic inracion ffcs (Eq. (7)) using h las squar procdur as follows: Y = b b b x b x b x b x x b x x b x b x x b x (7) 0 x 3 3 whr y is h prdicd rspons associad wih ach facor lvl combinaion; Th cofficins in h quaion rprsn: h inrcp (b 0 ) is consan, h main (b,b, b3) ar linar ffc, quadraic ffc (b, b, b 33 ) and inracions (b, b 3, b 3 ) ffcs, rspcivly; xi and xj ar h codd valus of indpndn variabls; and is h rsidual rror. Validaion of h modl fi and significanc analysis of variabls wr prformd using analysis of varianc (ANOVA). Th rsuls wr analyzd by analysis of varianc (ANOVA) and a calculaion corrlaion cofficin (R ) bwn prdicd and xprimnal poins [34] Modl validaion and opimizaion Validaion s was mployd o xplor h prdicaion prformanc of h dvlopd modl. Morovr, h opimizaion procss variabls wr obaind for h AO7sysm basd on h D-opimaliy indx in h Sagraphics sofwar. Th las squar mhod was usd o calcula h modl cofficins hrough Eq. (3) using h Sagraphics sofwar (vrsion 4.). To valua h saisical significanc, ANOVA analysis (R, adjusd R, F-s and -s), normal plos and rsiduals analysis wr mployd. Th significanc of h rgrssion cofficins was appraisd by h F and Sudn s ss a h confidnc lvl of 95% [35] Exprimnal dsign To drmin h opimal condiions for h main paramrs, a Box Bhnkn dsign (BBD) was applid. For h adsorpion procss, significan variabls, such as h iniial dy concnraion, flow ra, and bd high wr rgardd as h indpndn variabls and dsignad as X X 3, rspcivly. Th dy concnraion (X ) rang of 0 50 mg/l, flow ra (X ) rang of 6 ml/min, bd high (X 3 ) of 5 0 cm wr chosn as givn in Tabl. JMES, 07, 8 (3), pp

8 Tabl :Indpndn procss variabls and hir xprimnal lvls usd for Box Bhnkn Dsign (BBD). Variabls, uni Facors Lvls X Iniial dy concnraions of AO7 (mg/l) X Bd high (cm) X Flow ra (ml/min) X Slcion of h significan paramrs Th Box Bhnkn dsign consiss of 5 xprimnal poins. Th xprimnal condiions and h adsorpion capaciy obaind for ach poin s by h Box Bhnkn dsign ar shown in Tabl 3 ( ), oghr wih h hr cnral poin rpiions ( 5). Th rlaionship bwn rsponss and procssd variabls was xamind for h rspons approximaion funcion (Y) using Eq. (7), following by h saisical analysis of h modl obaind. Th mos significan procss variabls wr idnifid by Box Bhnkn dsign (BBD) xprimnal dsign. Th advanag of his dsign is is abiliy o invsiga of a larg numbr of facors in a rlaivly low numbr of xprimnal runs. In his sudy 5 run BBD wih 3 facors, including AO7 dy concnraion (X ), flow ra (X ) and bd high (X 3 ) was considrd. Each indpndn variabl was sd a wo lvls, high and low, which wr - and +, rspcivly. All xprimns wr conducd in duplica and h avrag valus of rmoval dy wr akn as a rspons (Y). Th marix dsign is shown in Tabl 3. On h basis of BBD hr h mos significan paramrs wr chosn for furhr invsigaion (modling and opimizaion by RSM). Tabl 3: Box Bhnkn Dsign marix wih codd and uncodd valus of h indpndn variabls influncing adsorpion of.ao7 by TES. Codd valus (uncodd valus) Exprimnal run No. X [ppm] X [cm] X 3 [ml/min] (50) 0 (0) - () 0 (30) 0 (0) 0 () 3 0 (30) 0 (0) 0 () 4 0 (30) - (5) (6) 5 0 (30) - (5) - () 6 - (0) 0 (0) (6) 7 0 (30) (5) (6) 8 (50) 0 (0) (6) 9 - (0) (5) 0 () 0 (50) (5) 0 () - (0) - (5) 0 (4) - (0) 0 (0) - () 3 0 (30) (5) - () 4 0 (30) 0 (0) 0 () 5 (50) - (5) 0 ().8.7. Analysis of varianc (ANOVA) ANOVA xpounds vry variaion in h saisically obaind modl and imporanc of ach modl paramrs. Th significanc of h modl was valuad by F-s for a confidnc lvl of 95% as wll as lack-of-fi s. In gnral, h grar h F-valu and h smallr h p-valu, h mor significan is a modl. Morovr, ffcs and hir imporanc in h modl wr invsigad adaping -s and p-valu. Usually, h largr h -valu and lowr probabiliy p-valu (p < 95%), h modl paramr is considrd as significan [36].Th sum of squars, dgr of frdom and man squars wr also drmind for h modl and rror. 3. Rsuls and discussion 3.. FTIR and DRX Spcral Analysis Analysis of FT-IR spcrum of TES biosorbn in h rang of cm - as shown in Fig..-a- shows som bands a 350 cm - ha ar assignd o OH srching mod vibraions du o inr-and inra-molcular JMES, 07, 8 (3), pp

9 Transmianc (%) Couns hydrogn bonding of polymric compounds. Th pak a 638cm - is du o asymmric srching vibraions of C=O and h pak obsrvd a 55cm - can b assignd o aromaic compound group and h srching and folding of carbona group has bn assignd o paks a 500 cm - and 865 cm -.Th X-ray diffracion of our biosorbn is shown in Fig..-b-.Th figur shows a main pak appard a Tha = 30. In addiion, his spcrum shows svral ohr small paks a Tha =.78, 35.88, 40.8, 48, 49, 54.78, 6.58, , , and 6. This spcrum confirms h prsnc of calci. -a- -b q dgr Wavnumbr (cm - ) Fig.: -a-ftir spcra and -b-x-ray diffracion parn of TES 3.. Effc of Iniial MB Concnraion and Conac Tim on MB Adsorpion To sudy h influnc of concnraion of h sorpion of MB on TES, 3g TES addd in ach 3 lirs of MB soluion wih iniial concnraions (5 00 mg/l) a 5 C. Th rsuls obaind ar shown in Fig. 3 and indica ha h upak ra of MB dy adsorbd pr gram of TES incrass gradually a h bginning and afr h adsorpion of MB rachd quilibrium a 00 min. W can say ha h quilibrium im is indpndn of h concnraion and h amoun adsorbd a quilibrium incrass wih concnraion from 5 o 6 mg/g, wih incras in h iniial MB concnraion from 5 o 00 mg/l. This is bcaus h diffusion of dy molculs from h soluion o h adsorbn surfac is acclrad by incrasing h sorba quaniy. Fig. 3: Kinics of MB adsorpion by TES a diffrn iniial concnraions 3.3. Effc of Tmpraur To drmin h ffc of mpraur on h biosorpion of h MB dy, xprimns wr conducd a 0, 5, 30 and 35 C. Th xprimns wr prformd by adding g/l of TES o h MB soluion a a fixd concnraion (80 ppm) and consan ph. Fig.4 shows ha h quilibrium upak prcnag of MB dy ions using TES was affcd by mpraur, i dcrasd wih an incras in mpraur, and i s du o h JMES, 07, 8 (3), pp

10 dcras of h physical forcs rsponsibl for sorpion. Furhrmor, h dcras upak of h caionic MB dy rmoval a highr mpraurs (abov 0 C) may b aribud o h dsrucion of som polymric aciv sis on h adsorbn surfac du o bond rupur, as wll as h dformaion of surfacs a highr mpraurs. Consqunly, h sudy found ha h opimum working rang was 0 C. Fig. 4: Effc of mpraur on h adsorpion of MB 3.4. Isohrm Modling of h Sorpion Equilibrium Dpnding on Tmpraur Analysis of h isohrm daa is imporan o dvlop quaions ha corrcly rprsn h rsuls and could b usd for dsign purposs. Tabl 4 shows h fiing paramrs for h masurd isohrm daa for MB adsorpion ono TES on h linar forms of Langmuir, Frundlich, Dubinin Radushkvich(D R), gnralizd isohrm and Tmkin isohrms wr simulad. Tabl 4: Comparison of h Cofficins Isohrms Paramrs for MB Adsorpion ono TES Tmpraur( C) Modls Langmuir Q m (mg/g) K (l/mg) R Frundlich K f N R Tmkin k B b R (D-R) Q m (mg.g - ) K(mol /kj ) E(kJ/mol) R Th rsuls obaind from h form of Langmuir modl for h rmoval of MB ono TES ar showd in Tabl 4. I can b obsrvd ha h adsorpion isohrm of MB ono TES fis Langmuir isohrm wll wih highr JMES, 07, 8 (3), pp

11 corrlaion cofficins (R ) in comparison wih ohr isohrms, rflcing ha h adsorpion sis on h surfac of TES ar vnly disribud. According o Langmuir adsorpion isohrm, h Q max for MB ar calculad o b 00, 75.44, and mg.g - a 0, 5, 30 and 35 C rspcivly. W can s from h abl 4 ha h incras in mpraur lads o a dcras in h adsorbd amoun, i can b said ha h low mpraurs ar of mos inrs and h maximum monolayr capaciy Q m adsorbd a 0 C is 00 mg /g obaind from Langmuir modl. Th maximum adsorpion of MB on TES dcrass wih incrasing h mpraur, xhibiing h xohrmic naur of h adsorpion procss. Frundlich consans can b drmind from h plo of log (q ) vrsus log (C ). Thus w can gnra h valu of K F from h inrcp and /n from h slop. Th corrlaion cofficins, R >0.93, obaind in Tabl 4.Frundlich modl is comparabl o ha obaind from Langmuir modl linar form. This rsul indicas ha h xprimnal daa fid wll Frundlich modl. Th valus of n F ar highr han uniy, indicaing ha adsorpion of MB ono TES is a favorabl procss. Th Tmkin consans K and B ar calculad from h slop and h inrcp of q vrsus ln(c ). Th linar isohrm consans and cofficins of drminaion ar prsnd in Tabl 4. Examinaion of h daa shows ha h Tmkin isohrm is applicabl o h MB adsorpion ono TES judgd by high corrlaion cofficin (R ) 0.99, 0.996, 0.99 and In h D R modl, h plo of ln (q ) vrsus ε givs K (mol /(kj )) and h adsorpion capaciy, Q m (mg/g). Th consan K givs h man fr nrgy of adsorpion (E) pr molcul of h sorba whn i is ransfrrd o h surfac of h solid from infiniy in h soluion. Calculad D R consans for h adsorpion of MB on TES wr givn in Tabl 4. Th valu of rgrssion cofficin of D-R isohrm R ar 0.93, 0.97, and is lowr han h Langmuir valu and h Frundlich valu, in his cas, D R quaion rprsns h poorr fi of xprimnal daa han h ohr isohrm quaions. According o h calculad E as 5.8,.90,.80 and.90kj/mol rspcivly a 0, 5, 30 and 35 C, which ar bwn 8 and 6 kj/mol, h yp of adsorpion of MB on h TES was dscribd as chmical adsorpion. Th sparaion facor R L valus for h sorpion of MB dy on h ggshll biosorbn hav bn shown in Tabl 5. All R L valus fall bwn zro and on; his fac suppors h prvious obsrvaion whr h Langmuir isohrm was favorabl for dy sorpion for all sudid mpraurs. Tabl 5: Dimnsionlss Sparaion Facor (R L ) a Diffrn Iniial Dy Concnraions Sudid a Diffrn Soluion Tmpraurs for h Sorpion of MB Dy ono h TES Biosorbn T ( C) C (mg/l) Kinic modls Th biosorpion daa wr analyzd according o h psudo firs- ordr kinic modl by h plo of ln(q q ) vrsus. According o Fig.5, w s ha h firs ordr kinic modl is no chckd for all mpraurs bcaus h curvs ar no prfcly linar wih R < Furhrmor, h abl III shows ha h calculad q valus ar oo low compard wih xprimnal q valus. I is hrfor impraiv o chck h scond ordr modl. Th plos of /q vrsus giv sraigh lins a diffrn mpraurs as showd in Fig.6 wih high valus of R which ar grar han Thrfor, ha confirms h applicabiliy of h psudo-scond ordr quaion. Valus of h ra consan k and quilibrium adsorpion capaciy q wr calculad from h inrcp and slop of h plos of /q vrsus, rspcivly. All paramrs ar summarizd in Tabl 6which shows br rsuls for h psudo scond ordr modl han h psudo firs ordr. Pracically, h incras in mpraur from 0 o 35 C is accompanid by a dcras of q from o 40 mg/g rspcivly. Howvr, h rsuls obaind using h psudo-scond-ordr modl ar no nough o prdic h diffusion mchanism. JMES, 07, 8 (3), pp

12 Fig.5: Psudo-firs-ordr kinics for mhyln blu adsorpion ono ggshll a diffrn mpraur Fig.6: Plo of h psudo-scond-ordr modl a diffrn iniial MB mpraurs (0-35 C) Tabl 6: Comparison of h Firs- and Scond-Ordr Adsorpion Ra Consans and q Valus for Diffrn MB Tmpraur and TES T( C) Psudo s ordr Psudo scond ordr R 0-3.k q xp (mg/g) k (l/min) q (mg/g) R (g/mg min) H (mg/g.min), q (mg/g) Th Elovich paramrs α and β can b compud from h slop and inrcp of h linar plo of q vrsus ln, hy ar rpord in Tabl 7. Th inraparicl diffusion is anohr kinic modl dvlopd by Wbr and Morris ha should b usd o sudy h ra-limiing sp for MB adsorpion ono TES. Th inraparicl diffusion is h sol ra-limiing sp if q vrsus / plos pass hrough h origin, which is no h cas in Fig.7 I may b concludd ha surfac adsorpion and inraparicl diffusion wr concurrnly opraing during h mhyln blu ggshll inracions. Th valus of k diff and k diff as obaind from h slops of h wo sraigh lins ar lisd in Tabl 7. Th inraparicl diffusion ra consan K dif wr in h rang of mg/gmin / and i incrass wih an incras of mpraur. JMES, 07, 8 (3), pp

13 Tabl 7: Th Paramrs Obaind from Elovich Kinics Modl and Inraparicl Diffusion Modl Using Diffrn Eggshlls Tmpraurs Tmpraur 0 C 5 C 30 C 35 C Elovich 0. (g/mg) (mg/g min) R Inraparicldiffusion Kdiff C R Exraparicl diffusion Kdiff C R Bangham k 0 (ml/g/l) R Fig.7: Inraparicl diffusion modl plo for h adsorpion of MB ono TES a diffrn iniial mpraurs For inraparicl diffusion plos, h firs, sharpr rgion is h insananous adsorpion or xrnal surfac adsorpion ha can b aribud o h film diffusion. Th scond rgion is h gradual adsorpion sag whr inraparicl diffusion is h ra limiing. I confirms ha inraparicl diffusion was no h only ra limiing mchanism in h sorpion procss. Tabl 7 liss h kinic consans α and k 0 obaind from h Bangham's quaion by ploing log[c 0 /(C 0 mq )] agains log. Thus, whn mpraur passd from 0 o 35 C. h valu of α incrasd from o 0.85 and h valu of k 0 dcrasd from 7.75o (ml/g/l). Th xprimnal daa did no giv a good corrlaion. In addiion, i was found ha h corrlaion cofficins for h Elovich modl ar highr han hos obaind for Bangham's modl. This rsul sill confirmd ha h por diffusion is no h only ra-conrolling sp Thrmodynamic Paramrs of Adsorpion In adsorpion procsss, hrmodynamic paramrs ar h acual indicaors for pracical applicaion. Th valus of ΔH and ΔS wr drmind from h slop and h inrcp of h plo of lnk d vrsus /T.As shown in abl 8, h ngaiv valu of ΔH ( kj/mol) shows ha h adsorpion is xohrmic as procss. Th ngaiv valu of ΔS (-0.098kJ/mol. C) indica ha hr a rducion of disordr in h solid/soluion inrfac during h adsorpion procss. Th ngaiv valus of ΔG ha incrasd from kJ/mol o kJ/mol wih an incras in mpraur from 0 C o 30 C indica h sponanous naur of his biosorpion ha h adsorpion is mor favorabl a low mpraurs. JMES, 07, 8 (3), pp

14 rmoval dy Tabl 8:Thrmodynamic Paramrs Obaind from Isohrm Adsorpion of MB ono TES T ( C) K d (L/mg) Ln(K d ) ΔG (kj/mol) ΔH (kj/mol) ΔS (J/mol. C) Rspons Surfac Mhodology: Box Bhnkn Dsign Rspons surfac mhodology (RSM) is mor advanagous han h radiional singl paramr opimizaion bcaus i can sav im, spac and raw marial. In xprimnal dsign, a Box Bhnkn dsign (BBD) is a yp of RSM, and i is usd for opimizing h imporan procss variabls. Th mos imporan paramrs, which affc h fficincy of adsorpion of AO7 ono TES, ar AO7 dy concnraion, flow ra and bd high of h soluion in a coninuous fixd bd. In ordr o sudy h combind ffc of hs facors, xprimns ar prformd for diffrn combinaions of h physical paramrs using saisically dsignd xprimns. Th iniial dy concnraion rang sudid is bwn 0 and 50 ppm. Th flow ra is bwn and 6 ml/min. Th bd high is varid bwn 5 and 0 cm.th main ffcs of ach of h paramr on AO7 rmoval fficincy is givn in Fig.8. Fig. 8 shows ha h rmoval fficincy incrass wih incrasing AO7 dy concnraion and bd high and wih dcrasing flow ra. Consqunly, w no high AO7 rmoval fficincis a high iniial dy concnraion. Main Effcs Plo for rmoval dy iniial dy concnraion bd high flow ra Fig.8.Main ffcs plo of paramrs for AO7 rmoval fficincy. Tabl 9 shows h xprimnal rsuls of rmoval of AO7 in h soluion for h 5 xprimns. Using h xprimnal rsuls, h rgrssion modl quaions (scond-ordr polynomial) rlaing h rspons is dvlopd and is givn in Eqs. (7). Apar from h linar ffc of h paramr for h rspons, h RSM also givs an insigh ino h quadraic and inracion ffc of h paramrs. Ths analyss ar don by mans of Fishr s F s and Sudn s. Th Fishr s F s is usd o drmin h significanc of ach of h inracion among h variabls, which inurns may indica h parns of h inracions among h variabls. In gnral, h largr h magniud of F, h smallr h valu of P, h mor significan is h corrsponding cofficin rm. Th rgrssion cofficin, F and P valus for all h linar, quadraic and inracion ffcs of h paramr ar givn in Tabl 0for h rmoval of AO7. I is obsrvd ha h cofficins for h linar ffc of h facors iniial dy concnraion (p=0.036) for h rspons is significan xcp flow ra and bd high (P =.000 and p=0.393) for rmoval of dy is slighly lss significan. Howvr, for h rmoval fficincy of AO7, h inracion ffc of h variabls dy concnraion and bd high is found highly significan p=0.007 xmp h inracion bwn dy concnraion and flow ra (P = ). Consqunly, h bs fiing rspons funcion, for h AO7 rmoval fficincy modl ar hn convninly wrin as follows: Y = x 0.3x 0.446x 0.95xx.05xx3.583x 0.65xx x3 (8) JMES, 07, 8 (3), pp

15 Whr Y (%) is h rmoval dy of AO7 ; x, x and x3 ar h AO7 dy concnraion, flow ra and bd high rspcivly. Tabl 9:Th xprimnal daa for ao7 rmoval fficincy in soluion according o BBD. Rmoval dy Y [(%)] Exprimnal run No. Exprimnal valus Prdicd rsponss Tabl 0:Analysis of varianc and corrsponding f and p valus for AO7 rmoval fficincy. Sourc Sum of Squars Df Man Squar F-Raio P-Valu A:inial concnraion B:bd high C:flow ra AA AB AC BB BC CC Toal rror Toal (corr.) Th ANOVA abl pariions h variabiliy in rmoval dy ino spara pics for ach of h ffcs. I hn ss h saisical significanc of ach ffc by comparing h man squar agains an sima of h xprimnal rror. In his cas, 3 ffcs hav P-valus lss han 0.05, indicaing ha hy ar significanly diffrn from zro a h 95 % confidnc lvl. Th R-Squard saisic indicas ha h modl as fid xplains % of h variabiliy in rmoval dy. Th adjusd R-squard saisic, which is mor suiabl for comparing modls wih diffrn numbrs of indpndn variabls, is 7.70 %. Furhr, h ANOVA for AO7 rmoval fficincy in soluion indicas ha h scond-ordr polynomial modl Eqs. (8) is highly significan and adqua o rprsn h acual rlaionship bwn h rspons and variabls, wih vry a high valu of cofficin of drminaion (R = for AO7 rmoval fficincy in soluion. This implis ha 89.89% of sampl variaion for AO7 rmoval fficincy in soluion is xplaind by h modl. Th saisical significanc of h raio of man squar variaion du o rgrssion and man squar rsidual rror is sd using ANOVA. ANOVA is a saisical chniqu ha subdivids h oal variaion in a s of daa ino componn pars associad wih spcific sourcs of variaion for h modl. According o h ANOVA (Tabl 0), h F saisics valus for all rgrssion ar highr. Th larg valu of F indicas ha mos of h variaion in h rspons can b xplaind by h rgrssion quaion. Th associad P valuis usd o sima whhr F saisics is larg nough o indica saisical significanc. Th ANOVA abl also shows a rm for rsidual rror, which masurs h amoun of variaion in h rspons daa lf unxplaind by h modl. Th form of h modl chosn o xplain h rlaionship bwn h facors and h rspons is corrc. Th 3D rspons JMES, 07, 8 (3), pp

16 surfac and D conour plo ar gnrally h graphical rprsnaion of h rgrssion quaion. W will us i o sarch h opimal valus of h procss paramrs. Thn, h rspons surfac plos and conour plos o sima h rmoval fficincy (Figs. 9 and 0) is givn. Fig.9.Rspons surfac plo of AO7 rmoval fficincy.fig.0.conour plo of simad rspons surfac of AO7 rmoval fficincy. Thus, h surfac and conour plos for AO7 rmoval fficincy in Fig. 0 shows h inracion ffc of bd high and iniial concnraion.th rspons surfac of muual inracions bwn h variabls is found o b llipical and h maximum AO7 rmoval fficincy is obaind in h following cass: Th bd high and iniial concnraion incras simulanously. Th iniial concnraion incrass and h bd high ar bwn 0 and 5 cm and rmain unchangd. Th bd high incrass and iniial concnraion is bwn 0 and 0 ppm and rmains sabl. Th gomrical rprsnaion of h rspons rmoval dy, whn h bd high and iniial concnraion incrass h rmoval dy incrass. W also no ha, h influnc of flow ra is no significan. Thn, o hav a good rmoval dy i is bnficial o work wih high bd high of column. Th highs valu of h bd high which givs maximum of AO7 rmoval is 5 cm. Conclusions In his sudy, w hav invsigad h fficincy of Eggshll rad by NaOH (TES) in rmoving h caionic dy mhyln blu (MB) andanionic dy AO7 from aquous soluion. In bach sudy TES could almos rmov ovr 75% of MB wihin 00 min conac im; Th quilibrium im is indpndn of h iniial concnraion of h soluion and h amoun adsorbd a quilibrium incrass wih concnraion, his is bcaus h diffusion of dy molculs from h soluion o h surfac of h adsorbn is acclrad by incrasing h dy concnraion. Th adsorbd amoun dcrass wih incrasing mpraur. Rsuls indica also ha h adsorpion isohrm daa wr fid good agrmn wih h Langmuir isohrm modls by comparing h valus of h linar corrlaion cofficin R², h adsorpion capaciy was found o b 00 mg.g - a 0 c. Th adsorpion procss followd psudo-scond ordr kinics and was sponanous and xohrmic; furhrmor, h inraparicl diffusion was no h only ra limiing mchanism in h sorpion procss. Th coninuous sudy clarly dmonsrad h applicabiliy of adsorpion procss using h fixd bd for AO7 rmoval. This sudy clarly showd ha RSM is on of h suiabl mhods o opimiz h bs opraing condiions o maximiz h AO7 rmoval. BB dsign is succssfully mployd for xprimnal dsign and analysis of rsuls. Th TES, which was usd wihou furhr purificaion for h rmovals of AO7 from aquous soluion bcaus i lans, clos o pracical purposs. Th procss variabls of rmoval of dy by TES hav bn opimizd basd on RSM mhod and h individual and inracion ffcs of h procss variabls wr invsigad. Th rsuls indicad ha all h hr procss variabls hav a dirc rlaionship for h rmoval AO7 dy ono TES. Saisfacory mpirical modl quaions ar dvlopd for h rmoval of AO7 in soluion using RSM o opimiz h paramrs. Graphical rspons surfac and conour plo is usd o loca h opimum poin. This sudy shows ha TES is an ffciv biosorbn for rmoval of anionic and caionic dys from aquous soluions. JMES, 07, 8 (3), pp

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