Application of Coconut Shell's Activated Carbon for Heavy Metal Removal from Wastewater

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1 Americn-Eursin Journl of Toxicologicl Sciences 8 (): 77-8, 06 ISSN IDOSI Publictions, 06 DOI: 0.589/idosi.ejts Appliction of Coconut Shell's Activted Crbon for Hevy Metl Removl from Wstewter, Md. Aminul Islm nd Md. Imrn Kbir Deprtment of Civil nd Environmentl Engineering, Shhjll University of Science nd Technology, Sylhet - 34, Bngldesh Chungju Ntionl University, 7 Dehkro, Chungju, South Kore Abstrct: This study ws conducted with btch nd continuous column type lbortory experiments to remove hevy metls nd orgnic mtter by using ctivted crbon of coconut shell (ACCS). Synthetic wstewter ws used to evlute the hevy metl removl cpbility t strting ph of 6.5. The sorbent dosges in the predetermined synthetic solutions were 0, 6.7 nd 0gL. In the btch tests, the column ws continuously operted for 4 dys t 00 to 5Lh until equilibrium concentrtion ws chieved. Moreover, the lbortory column showed removl efficiency (RE) of 00% without ny desorption. The dt fit the Freundlich isotherm model. The btches with low hevy metl concentrtions of Cd, Cu nd Zn exhibited n RE of pproximtely 99%, wheres 87 to 00% of Pb ws removed from most of the btches, indicting the superior effectiveness of the procedure. In ddition, the full-scle column filter with 0L ACCS filter ws cpble of reducing bout 30% of the totl orgnic crbon (TOC) nd 50% of hydrogen peroxide (HO ) from semiconductor wstewter t continuous flow rte of pproximtely 5L h. Key words: Activted Crbon Coconut Shell Hevy Metl Isotherm Sorbent INTRODUCTION removl efficiency increses with bed height nd detention time [5]. Activted crbon from lge mrine Adsorption using commercil ctivted crbon is n + Grcilri is cpble to remove hevy metl (Ni ) from effective but expensive purifiction nd seprtion queous solutions [6]. Pltnus orientlis leves were technique used in industry, especilly in wter nd used to remove Cd from queous solution, where the sh wstewter tretments to remove hevy metls [, ]. The of these leves showed more fvorble thn living ones hevy metls dischrged into the qu-environment [7]. The min objective of this study ws to evlute the present specil concern s they re bounded to efficiency of ACCS s sorbent for metl retention in bioccumultion nd excessive concentrtions re lbortory tests under well-controlled experimentl ssocited with vrious diseses in humns nd nimls. conditions. After getting promising results obtined from Here, ctivted crbon of coconut shell (ACCS) nd btch tests, set of columns were developed to full-scle column filter pcked with ACCS were used in investigte the possibility of using ACCS under lbortory, btch nd column study. Wlnut, hzelnut, continuous flow conditions. lmond nd pistchio shell-bsed ctivted crbon ws used to remove Cd, Cu, Pb nd Zn from queous solution MATERIALS AND METHODS []. Activted crbon from plm shell lso hs Pb dsorption bility [3]. The pper mulberry bio-chr ws Sorbents: Sorbent mterils with similr prticle size more effective nd exhibited higher dsorption potentil were used s prticle size my hve n effect on the for cdmium, copper, chromium, led nd zinc thn removl of hevy metls [8, 9]. ACCS ws sieved to the commercilly vilble silic powder [4]. Grnulr desired prticle size (0.6 ~ mm) nd dried t 40 C for 3h ctivted crbon is used to remove only Pb from without dditionl tretment before being used in the wstewter by reverse fluidized technology, where btch experiments [7]. Corresponding Author: Md Aminul Islm, Deprtment of Civil nd Environmentl Engineering, Shhjll University of Science nd Technology, Sylhet-34, Bngldesh. Cell:

2 Am-Eurs. J. Toxicol. Sci., 8 (): 77-8, 06 Tble : USEPA limit vlues nd initil concentrtions ( C) of hevy metls Concentrtions (µg L ); [ used for 0g L sorbent dosge] Cd Cu Pb Zn USEPA Btch 767; ; ; 979 Btch 3834; ; ; 900 Btch 3 567; 4 703; ; 476 Btch 4 763; 0 893; ; 339 Btch 5 409; 463; ; 56 Btch 6 94; 9 8; ; 4 Btch 7 43; 3 5; ; 7 Btch Hevy Metl Concentrtions: In this study, we ttempted to use relistic concentrtion rnges where the lowest vlues were below or bout US Environmentl Protection Agency (USEPA) fresh wter cute limits [0] nd the highest vlues were significntly higher, s shown in Tble. The purpose ws to evlute nd compre the sorbents t both highly nd slightly polluted conditions, since some sorbents re effective t rther high concentrtions but re less efficient t low concentrtion [8]. Btch Experiments: Sorption experiments were crried out using synthetic solutions in 50 ml bekers t room temperture (8± C). The required concentrtions of Cd, Cu, Pb nd Zn were obtined by step-by-step diluting their stock commercil solutions to the desired concentrtions. The ionic strength of the wter smples ws controlled using 0.0M NCl nd the ph chnges during the experiments were minimized using 0.003M NHCO 3 [8]. Before strting the btch experiments, the ph of ll solutions ws djusted to 6.5 using strong cid or bse solutions. Afterwrds, sorbent dosges were set t 0, 6.7 nd 0g L [8] in the predetermined synthetic solutions. The solutions nd sorbents were then mixed by gently shking the btches in mechnicl shker t 00 rpm for 4h. The ph vlues were checked fter the completion of the shking to identify ny possible ph vritions from the strting vlues. Lter, the btches were tken from the shker nd filtered through 0.45µm filter pper, fter which the filtrtes were cidified to ph.5 ~ nd stored t 4 C until the hevy metl mesurements. One set ws lso run s control btch with sorbent but without ny hevy metl ddition. All the chemicls used were regent grde nd were used without ny further purifiction. Column Experiment: The fixed bed columns were pcked with ACCS with prticle size rnge of 0.6 ~ mm nd used s up-flow rectors. Influent wter ws pumped through the ACCS-pcked column with peristltic pump. The column hd n inner dimeter of 55mm with 5mm high lyer of glss beds nd 95mm high lyer of ACCS. Fig. shows schemtic digrm of the column []. The columns were operted using upwrd flow t room temperture nd ir free distilled wter (without hevy metls) ws run through the columns for 4h prior to strting the experiments in order to wet the columns nd estblish equilibrium between the dsorbent nd wter. Uniform solution distribution, minimized pressure grdients nd reduced chnneling nd fouling of the dsorbent were chieved by using this design nd opertion procedure [-3]. During the 4-dy experiment, flow rtes were set t 00 to 5mL h nd inflow hevy metl concentrtions of.6,.7,.6 nd.8mg L of Cd, Cu, Pb nd Zn were used, respectively. Full-Scle Column Study: An ACCS-pcked column filter with n effective volume of 0L ws studied. A continuous downwrd flow of contminted wter t 5L h ws provided throughout the 45-dy study with strting ph of 3±0.08. Semiconductor industril wstewter with significnt concentrtion of totl orgnic crbon (TOC) nd hydrogen peroxide (HO ) ws used directly. In the influent (Inf.), Iron (Fe) (<0.05mg L ), luminium (Al) (<0.mg L ) nd Cu (<0.05mg L ) showed very low concentrtions. Smples were collected fortnightly nd stored until mesurement. Anlyzing Sorption Dt: For ACCS, the solid phse hevy metl concentrtion, q e (µg g ), ws determined by nlyzing the corresponding hevy metl concentrtion before nd fter the tretment using eqution (): C0 Ce qe = Eqution () X where C e is the equilibrium hevy metl concentrtion in the solution (µg L ) nd X the sorbent dosge (g L ). The metl removl efficiency percentge [, 4] of the dsorbent ws defined by Eqution (), while Eqution (3) ws used s the liner form of the Freundlich isotherm to fit the sorption dt: C (%) 0 C RE = e 00 Eqution () C0 log qe = log K + logc Eqution (3) e n where K is correlted with the quntity of sorbte ssocited with the sorbent nd n is the Freundlich isotherm constnt relted to the sorption strength [6, 7 & 5]. 78

3 Fig. : Schemtic digrm of the dsorption column nd the column detil RESULTS AND DISCUSSION Am-Eurs. J. Toxicol. Sci., 8 (): 77-8, 06 Physicl Properties: The removl of hevy metls from wstewter by griculturl wstes is green chemistry method for improving environment clenliness []. Fig. shows n imge, tken by environmentl scnning electron microscope (E-SEM), showing the stisfctory surfce of n ACCS prticle with voids to dsorb hevy metls. The Fourier trnsform infrred (FTIR) spectr reveled indicted the different surfce structures of the crbon such s liphtic, romtic nd cyclic s observed by the bnds t 460 cm nd over the cm 50%. rnge. All the nlyzed spectr possessed bnds t 0g L, respectively, showed removl below USEPA limits. In other cses, the btches with reltively low hevy metl concentrtions showed better results for ll sorbent dosges. Removl Efficiency (RE) in Column Test: The removl efficiencies of the hevy metls in the column test re shown in Fig. 4. For the C e mesurement, smples were collected t, 6, 8, 36, 7, 96, 68 nd 37h fter the strting time. Pb showed n RE of 94% fter h wheres Cu showed n RE of nerly 00% fter 6h. To check the desorption criteri, the column ws run continuously for 4 dys. No desorption ws observed s the column showed stisfctory results while mintining constnt C e for 4 dys. Full-Scle Column Filter: Tble shows the influent nd effluent concentrtion of semiconductor wstewter during the study. The hevy metl concentrtion ws nerly the sme in the effluent s in the influent, indicting the bsence of ny leching inside the column. Moreover, TOC nd HO were reduced by pproximtely 30 nd 50%, respectively, with respect to the influent levels. The continuous flow exhibited better long-term performnce in hevy metl removl nd other experimented prmeters, thereby demonstrting the longevity of the column. The HO efficiency ws reduced by nerly 33% on the third dy of study. Subsequently, RE of H O ws mintined nerly constnt t round cm, reveling the presence of lcoholic, Influence of Dosge: The RE ws corrected for the mss phenolic or cidic OH with hydrogen bonding. The peks of dsorbent in the btches nd is given s the mount of t cm were ttributed to the C=C group nd metl ion removed per unit sorbent dosge (g L ). Fig. 5 those t cm to the C=N group. The bnds t shows the RE per dosge of dsorbent versus the mount cm were considered to correspond to C=N=S of sorbent dosge, while the other prmeters re or C=N=C. These results indicted tht crbon possesses mintined constnt. The figure shows tht the RE per similr structure to tht of stndrd ctivted chrcol, dosge of the dsorbent generlly improved with but hs greter cpcity to remove hevy metls []. decresing dose for Cd, Cu nd Pb, while for Zn it very slightly incresed with incresing sorbent dosge. Equilibrium Concentrtions for Btch Tests: The results of the simultneous removl of Cd, Cu, Pb nd Zn using Removl Efficiency (RE) of Hevy Metls: The hevy different sorbent dosges re presented in Fig. 3 on metl RE from contminted wter t vrious sorbent double logrithmic scle for btch tests. As expected, the dosges is shown in Fig. 6. To investigte the reltion, mount of hevy metl removed incresed with incresing men vlues for ll btches t different sorbent dosges initil hevy metl concentrtion in ll of the btches. were divided by the respective dosge. The RE of Pb ws For the Zn dsorption, stisfctory removl ws bove 87% for ll the btches t sorbent dosge of 6.7g observed t the sorbent dosge of 0g L for ll btches. L while t sorbent dosge of 0g L, RE ws Three nd two btches t sorbent dosge of 6.7 nd incresed by 57% or more in ll btches except btch, 79

4 Am-Eurs. J. Toxicol. Sci., 8 (): 77-8, 06 Fig. : E-SEM imge of ACCS before being used s sorbent (pnel ()) nd FTIR spectr of ACCS (pnel (b)) Fig. 3: Cd, Cu, Pb nd Zn removl using different sorbent dosges ( 0g L, 6.7g L, 0g L ) Fig. 4: Removl efficiency (RE) ccording to time for Cd, Cu, Pb nd Zn Tble : Influent nd effluent properties of full-scle column Properties (mg L ) Inf. Eff. Inf. Eff. Inf. Eff. Inf. Eff. TOC H O Fe <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 Al <0. <0. <0. <0. <0. <0. <0. <0. Cu <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <

5 Am-Eurs. J. Toxicol. Sci., 8 (): 77-8, 06 Fig. 5: Influence of sorbent dosge on hevy metl removl efficiency (RE) Fig. 6: Effect of sorbent dosges [() 0g L, (b) 6.7g L nd (c) 0g L ] on removl efficiency (RE) of Cd, Cu, Pb nd Zn. Tble 3: Freundlich isotherm constnts for different sorbent dosges Sorbent dosge (g L ) Hevy metls K /n r K /n r K /n r Cd Cu Pb Zn which showed n RE of 35%. The RE of Cu ws mostly Sorption Isotherm: Tble 3 shows Freundlich isotherm bove 55% t sorbent dosge of 6.7g L. At higher constnts with the r vlues for ll sorbent dosges sorbent dosges, the dsorption of low concentrted investigted in this study. For Zn, t the sorbent dosges hevy metls ws round 99%. The RE of Cd nd Zn ws of 0 nd 0g L, the r vlues were very low, indicting reltively low for most of the btches t ll conditions. Zn poor correltion. For others, the r vlues of = 0.5 signify showed better RE t sorbent dosge of 6.7g L in sttisticlly significnt correltion. Although r = 0.5 btch 6 while very low RE ws chieved t sorbent shows fir correltion, using the estimted Freundlich dosge of 0g L, indicting the effect of sorbent isotherm for prediction is considered highly uncertin dosge. unless r is close to [8]. Accordingly, Pb showed the 8

6 Am-Eurs. J. Toxicol. Sci., 8 (): 77-8, 06 most correlted result to fit the isotherm. Cu showed 5. Gikwd, R.W., 0. Removl of led by reverse better correltion thn Cd s 0.87 = r = Furthermore, fluidiztion using Grnulr Activted Crbon. Irnic the isotherm mintined the correltion with r = 0.5 for Journl of Energy nd Environment, 3(4): Cd. 6. Esmeili, A. nd S. Ghsemi, 009. Evlution of the CONCLUSIONS ctivted crbon prepred of lge mrine Grcilri for the biosorption of Ni (II) from queous solutions. World Applied Sciences Journl, 6(4): The present study results hve demonstrted the 7. Mhvi, A.H., J. Nouri, G.A. Omrni nd F. Gholmi, potentil effectiveness of ACCS in hevy metl removl Appliction of Pltnus orientlis Leves in Stisfctory results were chieved for hevy metl RE in removl of Cdmium from queous solution. World both for the btch nd continuous studies. The hevy Applied Sciences Journl, (): metl RE ws dependent on the sorbent dosges with 8. Genç-Fuhrmn, H., P.S. Mikkelsen nd A. Ledin, 007. lower sorbent dosges exhibiting better RE thn higher Simultneous removl of As, Cd, Cr, Cu, Ni nd Zn dosges. ACCS ws found to be suitble for btch from stormwter: Experimentl comprison of tretment with low hevy metl concentrtions. No different sorbents. Wter Reserch, 4: sorbent leching occurred during the btch tests nd 9. Smith, E.H., 998. Modeling btch kinetic studies of full-scle studies, indicting n cceptble dsorbent cdmium removl by recycled iron dsorbent. qulity. The porous surfce nd FTIR spectr reveled Seprtion Science nd Technology, 33(): properties similr to those of stndrd ctivted crbon. 0. USEPA, 007. Recent recommended wter qulity criteri. Avilble on ( REFERENCES wterscience/criteri/wqcriteri.html).. Genç-Fuhrmn, H., H. Bregnhøj nd D. McConchie,. Gun-Ko, V.M., R. Lebod, J. Skubiszewsk-Zieb, 005. Arsente removl from wter using snd-red B. Chrms nd P. Oleszczuk, 005. Crbon mud columns. Wter Reserch, 39: dsorbents from wste ion-exchnge resins. Crbon,. Ko, D.C.K., J.F. Porter nd G. McKy, 00. Film-pore 43: diffusion model for the fixed bed sorption of copper. Kzemipour, M., M. Ansri, S. Tjrobehkr, nd cdmium ions onto bone chr. Wter Reserch, M. Mjdzdeh nd H.R. Kermni, 008. Removl of 35: led, cdmium, zinc nd copper from industril 3. DcMrco, M., A.K. SenGupt nd J.F. Greenlef, wstewter by crbon developed from wlnut, 003. Arsenic removl using polymeric inorgnic hzelnut, lmond, pistchio shell nd pricot stone. hybrid sorbent. Wter Reserch, 37: Journl of Hzrdous Mterils, 50: Mohn, S. nd K. Sumith, 008. Removl of Cu (II) 3. Issbyev, G., M.K. Arou nd N.M. Sulimn, 008. by dsorption using Csurin Equisetifoli brk. Continuous dsorption of led ions in column Environmentl Engineering Science, 5: pcked with plm shell ctivted crbon. Journl of 5. Abs, S.N.A., M.H.S. Ismil, M.L. Kml nd S. Izhr, Hzrdous Mterils, 55: Adsorption process of hevy metls by 4. Adil, S., A. Mshitullh, M. Asthm, J. Abid nd low-cost dsorbent: review. World Applied A. Ghffr, 04. Hevy metl removl efficiency of Sciences Journl, 8(): Pper Mulberry Biochr nd commercilly vilble silic powder from simulted industril wstewter. Irnic Journl of Energy nd Environment, 5(4):