2009) 3( 22مجلة ابن الهیثم للعلوم الصرفة والتطبیقیة المجلد طة النباتات المائیة االتوازن الحراري ألزالة الكروم من المیاه الملوثة بوس بطریقة االمتزاز محمد صادق سلمان جامعة بغداد ،االلكترونیة مركز الحاسبة الخالصة مــن خـالل اســتخدام نبــات القصــب المــائي فــي عملیــة ازالــة 2006عــام ) الجادریــة(بغــداد اجریـت الدراســة فــي مـع أخـذ بنظـر االعتبـار ) الوجبة( من المیاه الملوثة من خالل عملیة امتزاز بطریقة الحجم الثابت ) الكروم(العناصر الثقیلة دورة 300(سـرعة الــرج و، ) لتـر/ملغـرام 60(طبیعـة حامضـیة وثبـوت كـل مــن التركیـز االولـي للكـروم ياختیـار محلـول ذ ) القصـب( مـع أخـتالف اوزان المـادة الصـلبة ) سـاعات 4( زمـن الـتالمس ،و) درجـة مئویـة 30(درجة الحـرارة و ، ) بالدقیقة وكانـت نسـبة االزالـة لكـل وزن مـن . مـل مـن محلـول الكـروم 100حجـم ينمـوذج ذأغـرام لكـل ) 0.5، 1، 2، 3، 4( وكـان منحنـي التـوازن للتزكیـز لكـل وزن مـع كمیـة . علـى التـوالي% ) 8، % 17.5، % 31،% 40،% 50(لبة المادة الص وتبــین . علـى التـوالي) 0.97، 0.93(المـادة الممتـزة یطـابق مـودیالت النكمیــر و فرینـدلش بقیمـة مربـع عامــل االرتبـاط .ةز الزالة الملوثات من المیاه الملوثامتزا ةنتائج الدراسة امكانیة استخدام نبات القصب المائي ماد IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 The Equilibrium Iso therm Removal OF Chromium From Waste Water By Aquatic Plants Using Batch Process Adsorption M. S. Salman Computer Center,Unive rsity of Baghdad Abstract This st udy was carried out in Baghdad (Al-Jadiriy a) in 2006 by detecting ability of aquatic reed p lant to remove heavy metals (Chromium) from wast e water by batch p rocess of adsorp tion with considering that acidic solution is best selection for such p rocess with constant initial chromium concentration(60 mg/l),sp eed of shaking(300 rp m), temp erature (30 C o ) and const ant contact t ime (4 h) but with different weights of adsorbent (reed) (0.5 ,1 ,2 ,3 and 4 )gm for each 100 ml volume of sample . The results showed that the p ercentage of the removed chromium were ( 8% ,17.5% ,31% ,40% and 50%) resp ectively for each sample according to the mass of adsorbent used. Equilibrium isotherm curve showed a good fitt ing with langmuir model and frendlich model with square regression value for both of them( R 2 =0.93) (R 2 =0.97) resp ectively. The st udy results showed that aquatic reed p lant can be used as an adsorbent to remove the p ollutants from contaminated waste water. Key words equilibrium isotherm , Adsorp tion , Reed , Chromium , lan gmuir model , frendlich model . Introduction At least 20 metals are classified as toxic and half of these are emitt ed in to the environment in quantities that p ose risk to human health (1) . Chromium has both beneficial and detrimental p ossessing p rop erties. Two tables oxidation st ates of chromium p ersist in the environment, Cr(III) and Cr(VI) which have contrast ing toxicities motilities and bio availabilities. Herd on Cr (III) is essential in human nutrition (esp ecially in glucose metabolism). M ost of the hexavalent comp ounds are toxic. While Cr(III) is relatively innocuous and immobile. Cr(VI) moves readily through soils and aquatic environment and is a st orage oxidizing agent cap able of being absorbed through the skin (2). Chromium and its comp ounds are widely used in electrop lating, leather tanning cement , dy eing, metal p rocessing , wood p reservatives , p aint and p igments , textile st eel fabrication and canning industries. Wide range of p hy sical and chemical p rocesses is available for the removal of Cr(VI) from wast e water, such as electro-chemical p recipitation, ultra filtration, ion exchange and reverse osmosis (2) and (3). A M ajor drawback with p recipitation is sludge p roduction. Ion exchange is considered a bett er alternative technique for such a p urp ose. However it is not economically app ealing because of high op erational cost .Adsorp tion using commercial activated carbon (CAC) can remove heavy metals from wast e water such as cadmium, nickel, chromium, and cupp er. However (CAC) remains an exp ensive material for heavy metal removal . The technique of adsorp tion is where a solid surface in contact with a solution has the tendency to accumulate a surface lay er of solute molecule ,because of the imbalance of surface as –an adsorp tion takes p lace. The adsorp tion results in the formation of molecular IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 lay er of the adsorbate on the surface of adsorbent (solid).often an equilibrium concentration is rapidly forward . The surface is generally followed by a slow diffusion on to t he particles of the adsorbent (4) Using natural adsorbent for removing heavy metals from wast e water with clays and betonies (5) because of there permeability which play s an imp ortant not e as p hy sical barriers. And using biotechnology for such a p urp ose in bioreactor (6). Equate plouts is widly used as adsorbent because of its low cost materials. The removal of cadmium ,lead and zinc from wast e water were 32%,30% and 71%, resp ectively when maize cob was used as solid in adsorp tion process.(7) Using p eat as adsorbent in process of clays removal of dy es on fixed bed columns of different variable (PH ,bed dept ,size range ,and control time) (8). Adsorp tion isotherm is to examine the relationship between the amount of sorbet material (qe) and aqueous concentration Ce at equilibrium in batch p rocess of contact between solid and liquid at condition which must be fixed at t he beginning of p rocess. Sorp tion isotherm model is widely emp loyed for fitt ing the data of which the Longmuir and Frendlish equations are most widely used. The Longmuir model assumes that the up take of metal ions occurs on homogenous surface by mono lay er adsorp tion without any interaction between adsorbed ions. To get the equilibrium data initial concentrations Ci were kept constant . While the mass of adsorbent varied for at least 3hr of equilibrium p eriods for sorp tion. Longmuir equation as shown below (2) and (4). qe =KL Ce/(1+aL Ce) Where qe (mg/g) is the amount of metal ions adsorbed in to unit mass of the adsorbent to comp lete monolayer on the surface . KL is the Longmuir equilibrium constant which is related to the affinity of binding site. Ce the solution p hase metal ion concentration and Langmuir constant, KL and aL are the characterist ics of Longmuir equation and can be determined form linearzed from of the langmuir equation represented :- Ce/qe =1/KL +(aL/KL) Ce therefore a p lot of the Frendlich equation in an equation is based on adsorp tion on heterogeneous surface. The equation is commonly represented by qe= aCe where a and b are the Frendlich constant of the sy st em indicating the adsorp tion capacity and the adsorp tion intensive resp ectively to simplify the derivation of a and b, the above equation can be linearized as Ln qe=b Ln Ce+ Lna Therefore a p lot of Ln qe versus Ln Ce to determine b as slop and (1/b) must be (>1) and a as an intercept. (9) Experimental Work The exp eriment have been carried out in Baghdad (Al-Jadiriy a) in 2006 and all materials were prepared locally as shown below. -adsorbate The solution of chromium was p repared by dissolving of (70.7) mg of Pot assium Dichromate k2Cr2O7 in 500 ml dist illed water as shown in st andard method 1995, at p H=5 by adding drop s of Hcl (N 0.1) with stirring and measuring by p H meter. (2). -adsorbent IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 Reed was collected from (Al-Jadiriy a) location when it is grown naturally in Tigris river inside Baghd ad . p arts of this p lant were cut into small p arts (2 – 5mm) and washed by distilled water many times then dried by oven at 100 C 0 for 4hr. Equi librium uptake experime nt: The equilibrium exp eriment was carried out by using reed as adsorbent with mass (0.5, 1, 2, 3, 4) gm in five flask filled with 100 ml of the Cr st ock solution with initial concentration 60 mg/l. The exp eriment was carried out by using shaker for mixing adsorbent with adsorbate at sp eed 300 rp m contact time 4hr, temp . at 25C o and fixed concentration 60 mg/l, p H=5 of st ock and varied mass of adsorbent (reed). Aft er the time of shaking the samples were filtrated and the concentration of chromium was analyzed by flam Atomic absorp tion . Re sult and Discussion Fig(1) shows that increasing of the p ercentage adsorbed Cr with increasing of adsorbent mass was due to increasing in the surface area at number of sites. Equilibrium isotherm Fig(2) shows t hat t he ty p e of curve is favorable (4) due to its non linear relation. Equilibrium isotherm fits with Langmuir and Freundlich model Fig (3) & (4) because the (R 2 =0.93, 0.97 ) resp ectively and (1/b) constant is (1.85) when 1/b must be more than (1). (9) Both of theoretical and emp irical equilibrium isotherm are accep table as shown in the value of constant in Table (1) . Conclusion 1-Removal of Cr is increased with the increase of adsorbent mass. Because of the increase of surface area (5% - 50%) 2-Equilibrium isotherm is fitt ed with Langmuir and Frendlich models. 3-Possibility of making continuous exp eriment is fixed bed column but with low flow rate. 4-Low up take (qe) which is because of the unknown surface area need. 5-Low cost p rocess is comp ared with the costly p rocess by using commercial Activated carbon. 6-This method is achieved widely by wet land st udies to decrease the p ollutant in surface water. Nomuelctures - a Frendlich constant - aL Langmuir constant - b Frendlich const ant -Ce Initial conc. Of chromium (mg/l) - KL langmuir constant -q e Up take of sorbet chromium (mg/gm) Re ferences 1.KORtenkup, A; Casadevall ,Faux, S.P. (1996) Archives and Bio phy sics , 329 (2): 199-208 2.Saifudin, M .and Kumaran , P.( 2005)J. of Biotechnology .8(1): 3.Goel, P.K. (1997) "Water p ollution" New-age publishers, New dlebi IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 4.Johon,W.and Barry ,T . Critt enden(1998) "Adsorp tion Technology and design" Butter wort h – Heinemann , Oxford, Uk. 5.Vega, J.L.and Ay ala, J.(1995) 9 th international main water congress ,Pero. 6. Jamews, A. J., water and wast e water international, 1987, 2 (2): Ap ril p p 31 – 35,University of Piura,. Piuro, Peru, 9 th international mine water concerners PP. 603-609. 7 Abia, A. A. and Igwe, J.C.,African journal of Biotechnology , June, 4 (6): 509 – 512, 2005. 8. Poot s, V. J; M ckay , G. and Haely , J.J., (1975) Water research, 10:1061 – 1066 9.Casey, T. J."Unit of treatment p rocesses of wast e water" wiley serieo, New York, Industrial conferences on water and environ, 1992. Table(1) Constant value of langmuir and frendli ch models Fig. (1) percent of Cr removal at adsorbents mass Lan langmuir isotherm curve 1 aL= 27.474 mg / l / K L = 0.434 gm/ mg R 2 = 0.9328 Lan Frendlich isotherm curve ( -a = 1.185 mg/gm ( - b =0.5398 (1/b = 1.85) R R 2 = 0.9767 0 10 20 30 40 50 60 0 1 2 3 4 5 Mass of adsorbent (gm) % o f C r R e m o v a l IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 Fig.(2) Equi librium isotherm curve Fig. (3) langmui r model of e quilibrium isotherm 0 0.2 0.4 0.6 0.8 1 1.2 10 20 30 40 50 60 concentraion of Cr at equilibrium(mg/l) Ce A d s o rb e d C r p e r m a s s o f re e d (m g /g m )q e IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (3) 2009 Fig.(4) Frendlich model of equilibrium isothe rm y = 0.5388x + 0.1693 R 2 = 0.9767 1.9 2 2.1 2.2 2.3 2.4 3.2 3.4 3.6 3.8 4 4.2 Ln Ce L n q e