KINETICS AND ISOTHERM MODELING OF ADSORPTION OF RHODAMINE B DYE ONTO CHITOSAN SUPPORTED ZEROVALENT IRON NANOCOMPOSITE (C-nZVI)

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1 Intrnational Journal of Civil Enginring and Tchnology (IJCIET) Volum 9, Issu 13, Dcmbr 018, pp , Articl ID: IJCIET_09_13_159 Availabl onlin at ISSN Print: and ISSN Onlin: IAEME Publication Scopus Indxd KINETICS AND ISOTHERM MODELING OF ADSORPTION OF RHODAMINE B DYE ONTO CHITOSAN SUPPORTED ZEROVALENT IRON NANOCOMPOSITE (C-nZVI) A. Oluwasogo Dada * Industrial Chmistry Programm, Dpartmnt of Physical Scincs, Landmark Univrsity, P.M.B.1001, Omu-Aran, Kwara Stat, Nigria A. A. Inyinbor Industrial Chmistry Programm, Dpartmnt of Physical Scincs, Landmark Univrsity, P.M.B.1001, Omu-Aran, Kwara Stat, Nigria F. A. Adkola Dpartmnt of Industrial Chmistry, Univrsity of Ilorin, P.M.B. 1515, Nigria E. O. Odbunmi Dpartmnt of Chmistry, Univrsity of Ilorin, P.M.B. 1515, Nigria O. S. Bllo Dpartmnt of Pur and Applid Chmistry, Faculty of Pur and Applid Scincs, Ladok Akintola Univrsity of Tchnology, Ogbomoso, Nigria S. Ayo-Akr Industrial Chmistry Programm, Dpartmnt of Physical Scincs, Landmark Univrsity, P.M.B.1001, Omu-Aran, Kwara Stat, Nigria *Corrsponding Author s dada.oluwasogo@lmu.du.ng ABSTRACT Th kintics and isothrm modling of adsorption of Rhodamin B (RhB) Dy onto chitosan supportd zrovalnt iron nanocomposit (C-nZVI) was succssfully studid in a batch tchniqu. Th quantity adsorbd incrasd with incras in initial concntration from mg 4.37 mg for 00 ppm to 1000 ppm and high prcntag rmoval fficincy (%RE) of 99.7% attaind at 90 minuts contact tim. Equilibrium data wr analyzd by six isothrm modls: Langmuir, Frundlich, Tmkin, Dubinin-Kaganr-Raduskvich (DKR), Rdlich-ptrson and Halsy isothrm modl. Equilibrium data bst fittd to Frundlich isothrm supportd by Halsy isothrm modl. Langmuir monolayr adsorption capacity (56.41 mg/g) of C-nZVI obtaind gratr than most adsorbnt rportd for adsorption of RhB. Th man ditor@iam.com

2 Kintics and Isothrm Modling of Adsorption of Rhodamin B Dy Onto Chitosan Supportd Zrovalnt Iron Nanocomposit (C-nZVI) adsorption fr nrgy, E pr molcul valuatd from DKR modl was lss than 8 KJmol -1 indicating a physisorption mchanism. Th kintic data bst fittd to psudo scond-ordr kintic modl as validatd by sum of squar rror (SSE) statistical modl and th mchanism controlld by por diffusion. Th study rvald th grat potntial of C-nZVI for ffctiv rmoval of RhB dy. C-nZVI is thrfor rcommndd for civic and industrial fflunts tratmnt. Ky words: Chitosan-Iron Nanocomposit, Rhodamin B, Adsorption, Kintics, Isothrm modling Cit this Articl: A. Oluwasogo Dada, A. A. Inyinbor, F. A. Adkola, E. O. Odbunmi, O. S. Bllo, S. Ayo-Akr, Kintics and Isothrm Modling of Adsorption of Rhodamin B Dy Onto Chitosan Supportd Zrovalnt Iron Nanocomposit (C-nZVI), Intrnational Journal of Civil Enginring and Tchnology (IJCIET) 9(13), 018, pp INTRODUCTION Nanotchnology is an upcoming ara in th study of Chmistry. In viw of th marvlous us of nanotchnology, scintists carry out various studis in this most vital disciplin. Nanomatrials hav bn rportd to b applicabl in nvironmntal rmdiation, catalysis, dvlopmnt of optical dvics and mdicin [1-3]. Its application is continually growing and rsarchrs ar xploring th dvlopmnt of novl nano-adsorbnts for nvironmntal rmdiation [4]. Th rlas of dys into th nvironmnt via anthropognic activitis has bn a global concrn du to som advrs ffcts posd on th nvironmnt. Dys ar mostly usd in industris such as txtil, lathr, papr, plastics and cosmtics to impart colour on thir final products [5-6]. Th rlas of colourd wastwatr from ths industris may prsnt an cotoxic hazard and introduc th potntial dangr of bioaccumulation, which may vntually affct man and aquatics through th food chain. Wastwatr containing vn a minut amount of dys can svrly affct th aquatic lif du to th rduction of light pntration and dissolvd oxygn [7]. Th application of biopolymrs such as chitosan is on of th mrging adsorption mthods for th rmoval of dys and havy mtal ions, vn at low concntrations [8]. Chitosan is a typ of natural polyamino-saccharid, synthsizd from th dactylation of chitin, which is a polysaccharid consisting prdominantly of unbranchd chains of β-(1 4)- -actoamido--doxy-d-glucos. Chitosan is known as an idal natural support for nzym immobilization bcaus of its spcial charactristics such as hydrophilicity, biocompatibility, biodgradability, non-toxicity, adsorption proprtis, tc. [9]. Chitosan can b usd as an adsorbnt to rmov havy mtals and dys du to th prsnc of amino and hydroxyl groups, which can srv as an activ sit [10]. Thr ar two important advantags of chitosan as an adsorbnt: firstly, its low cost compard to commrcial activatd carbon; scondly, its outstanding chlation bhaviour. Espcially in th nvironmntal nginring fild. Chitosan and its drivativ hav attaind a good rputation as adsorbnts for th rmoval of various contaminants, including havy mtal ions or spcis, fluorids, dys, phnol and its drivativs, and many othr natural or man-mad pollutants [11]. Rhodamin B is th dy undr invstigation in this rsarch. It is a cationic dy commonly usd in txtil industry du to its good fastnss to fabrics and high solubility. Howvr, it has bn rportd to b carcinognic [1-13]. Although prvious rsarchrs hav invstigatd th rmoval of Rhodamin B dy and othr dy typs utilizing diffrnt nano-adsorbnt, ditor@iam.com

3 A. Oluwasogo Dada, A. A. Inyinbor, F. A. Adkola, E. O. Odbunmi, O. S. Bllo, S. Ayo-Akr BiOBr/montmorillonit composits [14], Magntic nanocomposit [15]; NiO nanoparticls [16]; Cobalt nanoparticls-mbddd magntic ordrd msoporous carbon [17]; tratd picarp of Raphia Hookri [18], microwav and chmically tratd Acacia nilotica laf [19]; activatd carbon [0], ric hull-basd silica supportd iron catalyst [1]. Howvr, thr is no rport on adsorption of Rhodamin B onto chitosan supportd zrovalnt iron nanoparticls (C-nZVI). Thr is no xtnsiv rport on th isothrm and kintics modling of adsorption of Rhodamin B onto C-nZVI. Thr ar various mthods of rmoving dys, and thy includ chmical prcipitation, mmbran procss, ion xchang, solvnt xtraction, lctrodialysis, and rvrs osmosis [13, ]. Ths mthods ar non-conomical and hav many disadvantags such as incomplt dys rmoval, high ragnt and nrgy consumption, and gnration of toxic sludg or othr wast products that rquir disposal or tratmnt [3]. Howvr, adsorption has provn to b suprior than othr tchniqus bcaus it is fficint and cost ffctiv. Various mthods hav all bn invstigatd in th rmoval of Rhodamin B as wll as othr typs of dys which ar calcarous, yt to our knowldg, th adsorption of Rhodamin B dy onto chitosan supportd zrovalnt iron nanocomposit (C-nZVI) has not bn rportd. Th objctiv of this study is to invstigat th modling of kintics and quilibrium data vis-à-vis th kintics, mchanism and isothrm modling of adsorption of Rhodamin B. Th kintics was studid using psudo-first ordr, psudo-scond ordr and intraparticl diffusion modls in ordr to dtrmin th rat and mchanism of adsorption procss. Th quilibrium data wr fittd to six isothrm modls: Langmuir, Frundlich, Tmkin, Dubinin-Kaganr-Raduskvich (DKR), Rdlich-Ptrson and Halsy isothrm modl. Adsorption kintics and isothrm modls wr invstigatd to dvlop an insight of controlling raction pathways (.g., chmisorption vrsus physisorption), dtrmin th mchanisms (.g. intraparticl diffusion) of th adsorption procss, prdict th rat at which a targt contaminant would b rmovd from aquous solutions and quantify th adsorptiv capacity of an adsorbnt (.g C-nZVI). Th rsults from this study can b usd to assss th fficacy of C-nZVI for dys rmoval and dsign a wast tratmnt ractor for industris.. MATERIAL AND METHODS.1. Chmical Ragnts All th ragnts usd wr of analytical grad mostly purchasd from Sigma-Aldrich, USA. Sodium Borohydrid (NaBH 4 ) (Sigma-Aldrich, USA) was usd for th chmical rduction, othr ragnts usd wr: Absolut Ethanol (BDH), Frric Chlorid (FCl 3 ), HNO 3, Rhodamin B Dy all purchasd from Sigma-Aldrich, USA... Synthsis of Chitosan Supportd Zrovalnt Iron Nanocomposit (C nzvi) Chitosan supportd iron nanocomposit was prpard using bottom-up approach via chmical rduction. Firstly, chitosan which srvd as th bas matrial and on of th prcursors was prpard following a similar procdur [4]. 4 g of Chitosan was dissolvd in 100 ml of % % actic acid; stir th mixtur for 4 hours using a magntic stirrr to nsur homognous mixtur. Thraftr, zrovalnt iron nanoparticl was prpard by chmical rduction following a procdur rportd by Dada t al.[5 7]. Accuratly wighd 10 g of nzvi was mix with 100 ml of 4% chitosan, ths wr stirrd thoroughly for anothr 4 hours with th aid of a magntic stirrr to nsur that chitosan anchors proprly into th matrix of th synthsizd zrovalnt iron nanoscal particls to form C nzvi nanocomposit. Th C nzvi was sparatd using vacuum filtration with 0.45µm Millipor filtr papr. Equation of raction is as statd blow: C + 4F BH 4 + 9H O C 4F +3H BO 3 + 1H + + 6H (1) ditor@iam.com

4 Kintics and Isothrm Modling of Adsorption of Rhodamin B Dy Onto Chitosan Supportd Zrovalnt Iron Nanocomposit (C-nZVI) Whr C rprsnts Chitosan.3. Prparation of stock solution of Rhodamin B M Rhodamin B was dissolvd in d-ionizd watr and mad up to mark in 1000 ml standard flask. Lowr concntrations of th absorbat usd for adsorption studis wr prpard using srial dilution. Working concntrations from ppm wr usd for th study..4 Batch Adsorption Exprimnt Effct of initial concntration and contact tim wr studid in a batch tchniqu at ph 3 and ambint tmpratur. 100 mg of th C-nZVI was addd to 5 cm 3 of RhodaminB (RhB) dy of ppm in a 50 cm 3 conical flask. Th mixtur was agitatd intrmittntly on th rgulatd mchanical shakr for 3 hrs and th rsidual concntration of RhB was dtrmind in triplicat using Biochrom Libra PCB 1500 Doubl Bam UV VIS spctrophotomtr. Effct of contact tim was studid from minuts at optimum conditions. Adsorption capacitis and th rmoval fficincy wr obtaind using Eqs. and 3 rspctivly [8]: q ( Co C ) V W Co C % E 100 (3) C o Th quilibrium data wr fittd into tn isothrm modls and th kintic data wr analyzd using psudo first-ordr, psudo scond-ordr and intraparticl diffusion modls. 3. THEORY 3.1. Adsorption Isothrm Modling Th intraction btwn RhB and th C-nZVI can b wll dscribd using isothrm modls. In this study tn isothrm modls wr utilizd in dscribing th quilibrium data vis-à-vis Langmuir, Frundlich, Tmkin, DKR, Rdlich Ptrson and Halsy. Prsntd in Tabl 1 ar th linar quations and corrsponding paramtrs plottd in fitting th isothrm modls. Th valuatd paramtrs wr dtrmind from th slop and intrcpt of thir linar plots as portrayd in Tabl Langmuir isothrm modl This modl assums a surfac monolayr and homognous adsorption that occurrd on finit numbr of idntical activ sits with uniform nrgis of adsorption. Each sit can accommodat on adsorbat and thr is no intraction btwn nighboring adsorbd molculs or atoms [5, 9]. Th Langmuir paramtrs q max (maximum monolayr covrag capacity, mg.g -1 ) and K L (Langmuir isothrm constant, L.mg -1 ) wr dtrmind from th slop and intrcpt of th linar plot. Th ssntial fatur of Langmuir isothrm may b xprssd in trms of th R L, which is rfrrd to as sparation factor or dimnsionlss constant as sn in Eq. 16 [7]: R L 1 1 K L C o Frundlich Isothrm Modl Th Frundlich adsorption isothrm (Tabl 1, Eq. 5) givs an xprssion ncompassing th surfac htrognity and th xponntial distribution of activ sits and thir nrgis. Th (16) () ditor@iam.com

5 A. Oluwasogo Dada, A. A. Inyinbor, F. A. Adkola, E. O. Odbunmi, O. S. Bllo, S. Ayo-Akr Frundlich isothrm constants, K f and n indicating th sorption capacity and intnsity rspctivly ar paramtrs charactristic of th adsorbnt-adsorbat systm Tmkin Isothrm Th Tmkin isothrm modl (Tabl 1, Eq. 6) dscribs th adsorbnt-adsorbat intraction as having th hat of adsorption of all molculs in th layr dcrasing linarly with th surfac covrag [3, 30]. Th paramtr b T is th Tmkin isothrm constant rlatd to th hat of sorption and A T is th Tmkin isothrm quilibrium binding constant (Lg -1 ) Dubinin-Kaganr-Raduskvich (DKR) isothrm modl DKR isothrm modl (Tabl 1, Eq. 7) givs insight into th physical and chmical natur of th adsorption procss. From th linar quation in Tabl 1, A D-R is th DRK isothrm constant (mol /kj ) rlatd to fr sorption nrgy and Q d is th thortical isothrm saturation capacity (mg/g).th mchanism of th procss was judgd from th man sorption fr nrgy, E pr molcul of RhB adsorbat computd by th rlationship in Eq. 17 [13, 5, 31]: E 1 A DR Rdlich-Ptrson (R-P) Isothrm modl Th R-P isothrm modl (Tabl 1, Eq. 8) combins both lmnts from th Langmuir and Frundlich isothrm modls as an mpirical isothrm incorporating thr paramtrs. Th mchanism of adsorption is a mix hnc dos not oby monolayr adsorption [3-33]. Whn β=1, it rducs to Langmuir quation with B=b (Langmuir adsorption constant (Lmg 1 ) which is rlatd to th nrgy of adsorption. A R-P = bq max whr q max is Langmuir maximum adsorption capacity of th adsorbnt (mgg 1 ) Halsy isothrm modl Th Halsy isothrm modl (Tabl 1, Eq. 9) is usd to valuat th multilayr adsorption at a rlativly larg distanc from th surfac. [34-35]. S/N Isothrms modls 1 Langmuir Frundlich 3 Tmkin Tabl 1 Diffrnt adsorption isothrms [3, 4, 3, 33, 36] Linar Equations Equations Plot Evaluatd Paramtrs C 1 C 4 C vs C q max, K L q q K Lqmax q max ogq ogk f 1 ogc 5 ogq n vs ogc K f, 1 n, and n RT RT 6 q ln AT lnc q vs nc A T, b T, β b b T 4 DKR nq nq A 7 5 Rdlich- Ptrson 8 Halsy C q m ln ln nq 1 nh C T DR nk ln A H RP 1 nh nc 8 9 nq vs C ln vs lnc nq vs nc q m,, (17) AD R AR P 1 n n,, K H H H ditor@iam.com

6 Kintics and Isothrm Modling of Adsorption of Rhodamin B Dy Onto Chitosan Supportd Zrovalnt Iron Nanocomposit (C-nZVI) 3.. Kintics Modling and Statistical Validity Th kintic data wr subjctd to psudo first-ordr, psudo scond-ordr and intraparticl diffusion modls in ordr to dtrmin th rat and mchanism of th adsorption procss Psudo-First Ordr Kintics Modl. Th linar form of psudo first ordr quation is gnrally xprssd as: ( ) k 1 Log q q Log q t t.303 (10) Whr q is th quantity of RhB adsorbd at quilibrium pr unit wight of th C-nZVI nano-adsorbnt (mg/g), q t is th amount of RhB adsorbd at any tim (mg/g) and k 1 is th psudo first-ordr rat constant (min -1 ). Psudo first-ordr paramtrs wr dtrmind from th plot of log(q q t ) against t [37] 3... Psudo-Scond Ordr Kintics Modl Th linar form of Psudo scond-ordr rat xprssion is givn by th xprssion: t 1 1 t qt k q q (11) Whn t tnds to 0, h is dfind as: h k q (1) Substituting h into Eq.0, it bcoms: t 1 1 t q h q t Whr h is th initial adsorption rat for psudo scond-ordr. (Th psudo scond ordr paramtrs dtrmind from th plot of t/q t against t [38] Intraparticl Diffusivibility Th intraparticl diffusion quation is xprssd as: q t k id t 0.5 C Whr k id is th intraparticl diffusion rat constant (mg.g 1 min 0.5 ) and C is th intrcpt indicating th thicknss of C-nZVI. Th q t is th amount of solut adsorbd pr unit wight of adsorbnt pr tim, (mg/g), and t 0.5 is th half adsorption tim [3, 4, 39] Validity of th Kintics Data Th suitability, agrmnt and bst fit among th kintic modls wr judgd using th statistical tools such as rgrssion cofficint (R ), sum of squar rror (SSE) Sum of squar rror (SSE) is th mostly usd by rsarchrs. Th mathmatical xprssion is givn in Eq. 3 [5, 6, 36, 39]: SSE n q, cal q,xp i1 3. RESULTS AND DISCUSSION 3.1. Bulk Dnsity, Moistur Contnt, Point of Zro Charg and FTIR Charactrization of (C-nZVI) Th synthsizd Chitosan supportd zrovalnt iron nanocomposit was charactrizd by point of zro charg (PZC), moistur contnt, and bulk dnsity (Physico-chmical (13) (14) (15) ditor@iam.com

7 A. Oluwasogo Dada, A. A. Inyinbor, F. A. Adkola, E. O. Odbunmi, O. S. Bllo, S. Ayo-Akr charactrization) and FTIR (spctroscopic charactrization). Th point of zro charg (PZC) is dfind as th ph at which that surfac ara has a nt nutral charg [5, 40]. Th PZC of C-nZVI found to b 4. This was significanc and suitabl for th adsorption of Rhodamin B at a ph blow th point of zro charg. Moistur contnt 7. and bulk dnsity gcm -3 wr indication of good quilibration of th C-nZVI with th adsorbat (RhB) thus prvnting floatation [41]. Th FTIR analysis of C-nZVI was don using SHIMADZU FTIR modl IR8400s Spctrophotomtr. This was don prior to th adsorption to dtrmin th functional groups, molcular nvironmnt of th adsorbnts and xamin th possibl sits of intraction of Rhodamin B with C-nZVI. Th FTIR spctrum of chitosan supportd iron nanoparticls prior to adsorption is shown in th Fig. 1, th spctra rvals th charactristic band at cm -1 indicating th prsnc of OH functional group on th surfac of th chitosan supportd zro-valnt iron. Th vibration band at th rgion of 1641cm -1 indicats th prsnc of C=O, th prsnc of iron nanoparticl is obsrvd at th rgion of cm -1 [4]. Figur 1: FTIR spctrum for C-nZVI 3.. Effct of Initial Concntration on Adsorption of Rhodamin B onto Chitosan supportd Zrovalnt Iron Nanocomposit (C-nZVI) Concntration plays a ky rol as a driving forc to ovrcom th mass transfr rsistanc btwn th Rhodamin B solution and C-nZVI. Fig shows th rmoval fficincy of RhB at diffrnt initial concntrations from 00 ppm to 1000 ppm. It was obsrvd that th adsorption capacity and rmoval fficincy incrasd with incras in concntration is du to th concntration gradint dvlopd at solid-liquid intrfac. At highr concntration of RhB, th activ sits of C-nZVI wr bombardd by mor of th dy molculs as th procss continud until a saturatd point was rachd. Th quantity adsorbd incrasd with incras in initial concntration du to th availability of th activ sits from mg 4.37 mg for 00 ppm to 1000 ppm. Mor so, rmoval fficincy incrasd from 98.65% to 99.7% until quilibrium was rachd btwn ppm. Advantagously, rmoval fficincy as high as 96% was attaind at highst concntration (1000 ppm) indicating th ffctivnss of C-nZVI in RhB adsorption. This finding is in support with th rport in th litratur [3, 4, 43] ditor@iam.com

8 RE (%) Q (mg/g) Kintics and Isothrm Modling of Adsorption of Rhodamin B Dy Onto Chitosan Supportd Zrovalnt Iron Nanocomposit (C-nZVI) 3.3. Effct of Contact tim on Adsorption of Rhodamin B onto Chitosan supportd Zrovalnt Iron Nanocomposit (C-nZVI) Contact tim is also an important factor in all transfr phnomna such as adsorption. Prsntd in Figur 3 is th contact tim at various initial concntrations. Th xprimntal conditions ar wll statd blow th plot. It was obsrvd that rat of raction was rapid from 10 min and quilibrium was attaind at 30 min indicating a fast adsorption nhancd by this novl chitosan supportd zrovalnt iron nanocomposit (C-nZVI) [4, 43]. This is on of th advantags of nanoadsorbnts. A stady stat approximation sts in and a quasi-quilibrium situation attaind all through from 30 minuts to 10 minuts Q Q (mg/g)@600ppm Q (mg/g)@1000ppm Q (mg/g)@400ppm Q (mg/g)@800ppm Initial Concntration (mg/l) t (min) Figur : Effct of Initial Conc. Exprimntal Conditions: C-nZVI Dos=100 mg, Tmpt= 5 o C, ph = 3, Tim = 90 minuts, Stirring Spd = 10rpm Figur 3: Effct of Contact Tim at Various Initial Conc Exprimntal Conditions: C-nZVI Dos = 100 mg T= 5 o C, ph = 3, Stirring Spd = 10 rpm 3.4. Kintics and Mchanism modling of Adsorption of Rhodamin B onto C-nZVI Prsntd in Figurs 4 6 ar linar plots of psudo first-ordr, psudo scond-ordr and intraparticl diffusion modls at various concntrations. Thir valuatd ar wll prsntd in Tabl. From th rgrssion cofficint (R ) point of viw, it was clarly obsrvd that th kintic xprimntal data gav th bst fits with th psudo-scond ordr kintic modl having a corrlation co-fficint of R >0.99 at all concntrations. Also, th clos agrmnt btwn th valus of xprimntal and calculatd quantity adsorbd,q, xp and q, cal rspctivly corroboratd that kintic data wr bst dscribd by psudo scond-ordr modl. This was validatd by th lowr valus of sum of squar rror (SSE) at all concntrations as obsrvd in Tabl. Th lowr th valus of SSE, th bttr th kintic modl in dscribing th kintic procss [5 8, 44]. Highr valus of SSE obsrvd in psudo first ordr (Fig. 4) from, , is an indication of poor fitting of psudo first-ordr modl ditor@iam.com

9 log(q -q t ) (mg/g) t/q t (min.g mg -1 ) A. Oluwasogo Dada, A. A. Inyinbor, F. A. Adkola, E. O. Odbunmi, O. S. Bllo, S. Ayo-Akr t (min) -4 log log log log log Figur 4 Psudo first-ordr kintic modl for modl adsorption of RhB onto C-nZVI ppm 400ppm 600ppm 800ppm 1000ppm tim (min) Figur 5: Psudo scond ordr kintic for adsorption of RhB onto C nzvi Figur 6: Intraparticl diffusion modl plot for adsorption of RhB onto C-nZVI Th dtrmination of th adsorption rat controlling stp nhancs undrstanding of th adsorption mchanism. In ordr to dtrmin th mchanism, kintic data wr tstd with Wbr s intraparticl diffusion modl. From th valuatd paramtrs in Tabl, clos valus and agrmnt among xprimntal, calculatd quantity adsorbd, q, xp and q, cal, and th intrcpt, C (boundary layr), highr rgrssion cofficint (R >0.9) and lowr valus of SSE confirmd that th mchanism was govrnd and controlld by por diffusion. Th intrcpt (C) which is th thicknss of th surfac givs information about th contribution of th surfac adsorption in th rat dtrmining stp. Th largr th intrcpt, th gratr th contribution of th por to adsorption [3]. Howvr, sinc th intraparticl diffusion plots (Figur 6) did not pass through th origin, it thrfor indicatd that intraparticl diffusion is not th only rat dtrmining stp [3, 44]. Tabl : Paramtrs of diffrnt kintic and mchanism modls of RhB dy adsorption onto C-nZVI Psudo First-ordr 00 ppm 400 ppm 600 ppm 800 ppm 1000 ppm k q,xp q,cal R SSE, , , , ,774.7 Psudo Scond-ordr 00 ppm 400 ppm 600 ppm 800 ppm 1000 ppm k x q,xp q,cal ditor@iam.com

10 Kintics and Isothrm Modling of Adsorption of Rhodamin B Dy Onto Chitosan Supportd Zrovalnt Iron Nanocomposit (C-nZVI) R h SSE 4.9x Intraparticl Diffusion 00 ppm 400 ppm 600 ppm 800 ppm 1000 ppm q, xp q, cal k ip (mg/g/min 0.5 ) C R SSE , , Adsorption Isothrm Modls for th Uptak of Rhodamin B using Chitosan Supportd Iron Nanocomposit (C-nZVI) Th intraction btwn RhB and th C-nZVI was wll dscribd using isothrm modls. In this rsarch, six diffrnt isothrm modls wr fittd to th quilibrium data vis-à-vis Langmuir, Frundlich, Tmkin, Dubinin-Kaganr-Radushkvich (D R), Rdlich-Ptrson, and Halsy isothrm modls and thir corrsponding quations as prsntd in Tabl 1. Linar plots of ths isothrm modls ar dpictd in Figur 7(A-J). Spcifically, th linar lastsquars mthod and th linarly transformd quations hav bn widly applid to corrlat sorption data. Judging from th corrlation cofficint, quilibrium data wr fittd to Langmuir isothrm modl with R = RL Valu indicats th adsorption natur to ithr unfavourabl or unfavourabl. It is unfavourabl if R L >1, linar if R L =1, favourabl if 0< R L <1 and irrvrsibl if R L = 0. Th valu of th sparation factor, R L (Fig 8) ranging from 3x x10-3 which is lss than unity is an indication of a favourably adsorption [3, 3, 45]. Howvr, basd on highr R valus obsrvd in Frundlich (Fig 7B), Rdlich Ptrson (Figur 7E) and Halsy (Fig. 7F), th adsorption procss is physisorption in natur hnc a multilayr adsorption. Both k f and n ar Frundlich constant and adsorption intnsity rspctivly. Th valu of 1/n f is lss that unity indicating high htrognity of th C-nZVI natur, valu of n (.39) lying btwn on and tn is an indication of normal and favourabl adsorption [7, 46]. From Tmkin isothrm modl (Fig 7C), low valu of hat of adsorption is an indications of physisorption mchanism and ndothrmic natur of th adsorption procss [8]. Dubinin- Kaganr-Raduskvich (DKR) isothrm modl (Fig 7D) givs insight into th physical and chmical natur of th adsorption procss. Sinc th magnitud of E (fr nrgy of transfr of on solut from infinity to th surfac of C-nZVI) is lss than 8 kj mol -1 (Tabl 3), th lctrostatic forcs coupld with por diffusion as a rsult of mass transport playd a substantial rol in adsorption procss supporting physisorption mchanism. This finding corroboratd th assrtion in Frundlich and Tmkin isothrm modls [34, 43]. Frundlich isothrm adquatly dscribd th quilibrium data than Langmuir suggsting a multilayr adsorption procss and this is supportd by th rsults from Halsy isothrm modls paramtrs (Tabl 3) [47-48] ditor@iam.com

11 ln q (mg/g) ln (C /q ) (g/l) ln q (mg/g) C /q (g/l) log q (mg/g) q (mg/g) A. Oluwasogo Dada, A. A. Inyinbor, F. A. Adkola, E. O. Odbunmi, O. S. Bllo, S. Ayo-Akr (A C (mg/l) (B log C (mg/l) (C ln C (mg/l) 6 (D) E (E) -4 - ln C (mg/l) (H) ln C (mg/l) Figurs 7 (A-F): Linar plots of: (A) Langmuir (B) Frundlich (C) Tmkin (D) DKR (E) Rdlich Ptrson (F) Halsy Isothrm modl Tabl 3: Isothrm modls paramtrs for adsorption of RhB onto C-nZVI Langmuir Frundlich Tmkin q max (mgg -1 ) k f 53.7 b T (J mol -1 ) K L (Lmg -1 ) /n f β(lg -1 ) 5 x 10-7 R L 3x x10-3 n f.3941 A T (Lg -1 ) 1 R 0.96 R R DKR Rdlich Ptrson Halsy q d A R-P 1.4x10-3 1/n H A DKR 5 x 10-7 B R-P n H E(KJ/mol) 1 q max 7.45x10-4 K H 7.34 x10-5 R R R CONCLUSIONS Chitosan supportd zrovalnt iron nanocomposit (C-nZVI) was succssfully prpard using a chmical rduction mthod in a singl pot systm. Th rsult from th bulk dnsity, moistur contnt and point of zro charg indicatd that C-nZVI was suitabl in th uptak of Rhodamin B. Thy wr charactrizd by Fourir Transform infra-rd spctroscopy to dtrmin th functional group prsnt. Th point of zro- charg (PZC) rvald that ths adsorbnts ar suitabl for th rmoval of cationic dys from wast watr bodis. It also furthr xplains th proprtis of th adsorbnts having a strong affinity for th rmoval of Rhodamin B dy from aquous solution; thir ffctivnss dpnds largly on thir composition. Th adsorption capacitis wr found to dpnd on th quantity of adsorbnts, contact tim and initial concntration. Th kintic data wr bst dscribd by psudo-scond ordr and th mchanism was govrnd by intraparticl diffusion. Th quilibrium data wr bst fittd to Frundlich isothrm modl supportd by Halsy isothrm modls indication a multilayr adsorption on htrognous surfac of C-nZVI. Th adsorption procss was physisorption as confirmd by th nrgy valus stimatd from Dubinin-Kaganr- Radushkvich modl which was found to b lss than 8kJ mol -1. Rsults obtaind from this study showd that C-nZVI is a potntial, ffctiv and fficint adsorbnt in th uptak of ditor@iam.com

12 Kintics and Isothrm Modling of Adsorption of Rhodamin B Dy Onto Chitosan Supportd Zrovalnt Iron Nanocomposit (C-nZVI) Rhodamin dy B (RhB) from aquous solution. C-nZVI is thrby rcommndd for tratmnt of civic wast. ACKNOWLEDGMENT Dada, Adwumi Oluwasogo and co-authors apprciat th Managmnt of Landmark Univrsity for th financial support and nabling nvironmnt providd for rsult orintd rsarch. REFERENCES [1] Dada, A. O., Adkola, F. A., Adymi, O, S., Bllo, M. O., Adtunji, C. O., and Awakan, O. J. (018). Book Chaptr Titld: Exploring th Effct of Oprational Factors and Charactrization Imprativ to th Synthsis of Silvr Nanoparticls. In: Book Titl: Silvr Nanoparticls - fabrication, charactrization and applications. Chaptr 9, pg Doi.org/10.577/intchopn ISBN [] Dada, A. O., Inyinbor, A. A., Idu, I. E., Bllo, O. M., Oluyori, A. P., Adlani-Akand, T. A., Okunola, A. A., Dada, O. Effct of oprational paramtrs, charactrization and antibactrial studis of grn synthsis of Silvr Nanoparticls, using Tithonia divrsifolia. PrJ (018) DOI /prj.5865 (in-prss) [3] Dada AO, Adkola FA, Odbunmi EO. Liquid phas scavnging of Cd (II) and Cu (II) ions onto novl nanoscal zrovalnt mangans (nzvmn): Equilibrium, kintic and thrmo-dynamic studis. Environmntal Nanotchnology, Monitoring & Managmnt. 8 (017) a, [4] Dada, A. O., Adkola, F. A., Odbunmi, E. O. Kintics and quilibrium modls for Sorption of Cu(II) onto a Novl Mangans Nano-adsorbnt. Journal of Disprsion Scinc and Tchnology 37(1), (016), [5] Ciardlli G, Corsi L, Marcucci M Mmbran sparation for wast watr rus in th txtil industry. Rs Consrv Rcy, 31, (000), [6] Inyinbor, A. A., Adkola, F. A., and Olatunji, G. A. EDTA Modifid Irvingia gabonnsis: An Efficint Biorsourc Matrial for th Rmoval of Rhodamin B. Pak. J. Anal. Environ. Chm. 16(), (015)38 47 [7] Robinson, T., MacMullan, G., Marchant, R., Nigam, P. Rmdiation of dys txtil fflunt: A critical rviw on currnt tratmnt tchnologis with a proposd altrnativ. Biorsourc Tchnology, 77 (001), [8] Crini.G. Non-convntional low cost adsorbnts for dy rmoval. Biorsourc Tchnology, 97, (006), [9] Prju, M. M. and Dragan, E. S. Rmoval of azo dys from aquous solutions using chitosan basd composit hydrogls. Ion Exchang Lttrs, 3 (010): 7-11 [10] Zhang J., Zhang, Y., Li, R., Pan Q. Synthsis, charactrization and adsorption proprtis of a novl chitosan drivativ.indian Journal of Chmical Tchnology, 19 (01), [11] Copllo, G. J., Varla, F., Vivot, R. M., Diaz, L. E. Immobilizd chitosan as biosorbnt for th rmoval of Cd(II), Cr(III) and Cr(VI) from aquous solutions, Biorsour Tchnol. 99, (008), [1] Inyinbor, A. A., Adkola, F. A. and Olatunji, G. A. Kintic and thrmodynamic modling of liquid phas adsorption of Rhodamin B dy onto Raphia hookri fruit picarp; Watr Rsourcs and Industry, Vol 15 (016), pg ditor@iam.com

13 A. Oluwasogo Dada, A. A. Inyinbor, F. A. Adkola, E. O. Odbunmi, O. S. Bllo, S. Ayo-Akr [13] Dada, A. O., Olalkan, A. P., Olatunya, A. M., Dada, O. Langmuir, Frundlich, Tmkin and Dubinin Radushkvich Isothrms Studis of Equilibrium Sorption of Zn + onto Phosphoric Acid Modifid Ric Husk. Journal of Applid Chmistry, 3(1), (01) a, [14] Xu, C., Wu, H., Gu, F. L. Efficint adsorption and photocatalytic dgradation of Rhodamin Bundr visibl light irradiation ovr BiOBr/montmorillonitcomposits,Journal of Hazardous Matrials 75 (014), [15] Singha, K. P., Gupta, S., Singha, A. K and Sinha, S. Exprimntal dsign and rspons surfac modling for optimization of Rhodamin B rmoval from watr by magntic nanocomposit, Chmical Enginring Journal 165 (010), [16] Motaharia, F., Mozdianfard, M. R., Salavati-Niasari, M. Synthsis and adsorption studis of NiO nanoparticls in th prsnc of H acacn ligand for rmoving Rhodamin B in wastwatr tratmnt. Procss Safty and Environmntal Protction, 93, (015), 8 9 [17] Tanga, L., Caia, Y., Yanga, G., Yuanyuan, L, Znga, G, Zhoua, Y, Lia, S., Wanga, J., Zhanga, S., Fanga, Y., H, Y. Cobalt nanoparticls-mbddd magntic ordrd msoporouscarbon for highly ffctiv adsorption of Rhodamin B. Applid Surfac Scinc 314 (014), [18] Inyinbor, A. A., Adkola, F. A. & Olatunji, G. A. Adsorption of Rhodamin B from Aquous Solution Using Tratd Epicarp of RaphiaHookri. Covnant Journal of Physical and Lif Scincs, (), (014), [19] Santhi, T., Prasad, A. L., Manonmani, S. A comparativ study of microwav and chmically tratd Acacia nilotica laf as an cofrindly adsorbnt for th rmoval of rhodamin B dy from aquous solution.arabian Journal of Chmistry,7, (014),: [0] Li, L., Liu, S., Zhu, T. (010). Application of activatd carbon drivd from scrap tirs for adsorption of Rhodamin B. Journal of Environmntal Scincs, (8) (010) [1] Gan, P. P., Li, S. F. Y. Efficint rmoval of Rhodamin B using a ric hull-basd silica supportd iron catalyst by Fnton-lik procss, Chmical Enginring Journal 9 (013), [] Dada, A. O., Inyinbor, A. A., Oluyori, A. P. Comparativ Adsorption of Dys onto Activatd Carbon Prpard From Maiz Stms And Sugar Can Stms. Journal of Applid Chmistry, (3) (01) b, [3] Dada, A.O.,Ojdiran, J.O., and Olalkan, A.P., (013). Sorption of Pb + from Aquous Solution unto Modifid Ric Husk: Isothrms Studis. Advancs in Physical Chmistry, Volum 013, /8445 pp 1-6 [4] Vakili, M., Rafatullah, M., Salamatinia, B., Abdullah, A. Z., Ibrahim, M. H., Tan, K. B., Gholami, Z., Amouzgar, P. Application of chitosan and its drivativs as adsorbnts for dy rmoval from watr and wastwatr: A Rviw. Carbohydr. Polym. 113, (014), [5] Dada, A. O., Adkola, F. A. and Odbunmi, E. O. Kintics, Mchanism, Isothrm and Thrmodynamic Studis of Liquid Phas Adsorption of Pb + onto Wood Activatd Carbon Supportd Zrovalnt Iron (WAC-ZVI) Nanocomposit. Cognt Chmistry Journal, 3(017) b : , pg 1-0. DOI: [6] Dada, A. O., Adkola, F. A. and Odbunmi, E. O. Novl zrovalnt mangans for rmoval of coppr ions: Synthsis, Charactrization and Adsorption studis. Applid watr Scinc, 7 (017) c, Doi: /s [7] Dada, A. O., Latona, D. F., Ojdiran, O. J. Adsorption of Cu(II) onto Bamboo Supportd Mangans (BS-Mn) Nanocomposit: Effct of Oprational Paramtrs, Kintics, ditor@iam.com

14 Kintics and Isothrm Modling of Adsorption of Rhodamin B Dy Onto Chitosan Supportd Zrovalnt Iron Nanocomposit (C-nZVI) Isothrms, and Thrmodynamic Studis. Journal of Applid Scincs and Environmntal Managmnt (JASEM) Vol. 0 (), (016), [8] Dada, A. O., Adkola, F. A., Odbunmi, E. O. Isothrm, kintics and thrmodynamics studis of sorption of Cu + onto novl zrovalnt iron nanoparticls. Covnant Journal of Physical and Lif Scincs, (1), (014), [9] Langmuir, I Th adsorption of gass on plan surfacs of glass, mica and platinum. Journal of th Amrican Chmical Socity, 40: (1918), [30] Tmkin, M. I., Pyzhv, V., Kintic of Ammonia Synthsis on Promotd Iron Catalysts. Acta Physiochim. URSS 1, (1940), [31] Dubinin, M. M Th potntial thory of adsorption of gass and vapors for adsorbnts with nrgtically non-uniform surfac. Chm. Rv. 60, (1960), [3] Brours, F., Al-Musawi, T. J., On th optimal us of isothrm modls for th charactrization of biosorption of lad on alga, Journal of Molcular Liquids, 1, (015),pp.46 51,015. [33] Ayawi, N., Eblgi, A. N., Wankasi, D. Modlling and Intrprtation of Adsorption Isothrms. Hindawi Journal of Chmistry, Volum 017, Articl ID , [34] Song, C., Wu, S., Chng, M., Tao, P., Shao, M., and Gao, G.. Adsorption Studis of Coconut Shll Carbons Prpard by KOH Activation for Rmoval of Lad (II) from Aquous Solutions. Sustainability, 6, (014), [35] Bhatt, R. R. and Shah, B. A. Sorption studis of havy mtal ions by salicylic acid formaldhyd catchol trpoly-mric rsin: Isothrm, kintic and thrmodynamics. Arabian Journal of Chmistry, 8(3), (015), [36] Foo, K. Y. and Hamd, B. H (010). Rviw: Insights into th modling of adsorption isothrm systms. Chmical Enginring Journal, 156 (010), 10. [37] Ho, Y. S., Chiu, W-T., Hsu, C-S., Huang, C-T. (004). Sorption of lad ions from aquous solution using tr frn as a sorbnt. Hydromtallurgy, 73 (004): [38] Ahmad, M. A., Puad, N. A. A., Bllo, O. S. Kintic, quilibrium and thrmodynamic studis of synthtic dy rmoval using pomgranat pl activatd carbon prpard by microwav-inducd KOH activation. Watr Rsourcs and Industry, 6 (014), [39] Boparai, H.K., Mra, J., and Dnnis, M. O. (011. Kintics and thrmodynamics of Cadmium ion rmoval by adsorption onto nano zrovalnt iron particls. Journal of Hazardous Matrial 186: [40] Jaafar MZ, Nasir AM, Hamid MF (013) Point of zro charg for sandston and carbonat rocks by straming potntial. Int J Pt Gosci Eng 1():8 90 [41] Kumar, Y. K., Muralidhara, H. B., Nayaka, Y. A., Balasubramanyam, J., Hanumanthappa, H. Hirarchically assmbld msoporous ZnO nanorods for th rmoval of lad and cadmium by using diffrntial puls anodic stripping voltammtric mthod. Powdr Tchnology 39 (013): [4] Vnkatraman, B.R., Gayathri, U., Elavarasi, S., and Arivoli, S. (01). Rmoval of Rhodamin B dy from aquous solution using th acid activatd Cynodondactylon carbon, Dr Chmica Sinica, 01, 3(1): [43] Olakunl, M. O., Inyinbor, A.A., Dada, A.O. & Bllo, O.S., (017) Combating dy pollution using cocoa pod husks: A sustainabl approach. Intrnational Journal of Sustainabl Enginring, 11 (1) (017), Pags 4-15, ditor@iam.com

15 A. Oluwasogo Dada, A. A. Inyinbor, F. A. Adkola, E. O. Odbunmi, O. S. Bllo, S. Ayo-Akr [44] Bllo, O. S, Ahmad, M. A, Smir, B. (014). Scavnging malachit grn dy from aquous solutions using pomlo (Citrusgrandis) pls: kintic, quilibrium and thrmodynamic studis. Dsalination and Watr Trat mnt 014)oi: / [45] Hao, Y-M; Chn, M; Hu, Z-B. Effctiv rmoval of Cu (II) ions from aquous solution by amino-functionalizd magntic nanoparticls, J Hazard Matrs. 184 (010): [46] Png, X., Lam, F. L. Y., Wang, Y., Liu, Z.,. Adsorption bhavior and mchanisms of Ciprofloxacin from aquous solution by ordrd msoporous carbon and bamboo-basd carbon. J. Colloid and Intrfac Sci, (015) doi: j.jcis [47] Xu, C., Wu, H., Gu, F. L. Efficint adsorption and photocatalytic dgradation of RhodaminBundr visibl light irradiation ovr BiOBr/montmorillonitcomposits,Journal of Hazardous Matrials 75 (014), [48] Wang, J., Zhng, S., Shao, Y., Liu, J Amino-functionalizd F 3 O 4 SiO cor shll magntic nanomatrial as a novl adsorbnt for aquous havy mtals rmoval. Journal of Colloid and Intrfac Scinc, 349: ditor@iam.com