Biosorption of chromium(VI) from aqueous solution by cone biomass of Pinus sylvestris

Biosorption of chromium(VI) from aqueous solution by cone biomass of Pinus sylvestris
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  Biosorption of chromium(VI) from aqueous solutionby cone biomass of   Pinus sylvestris Handan Ucun  a , Y. Kemal Bayhan  a , Yusuf Kaya  b , Avni Cakici  a,* , O. Faruk Algur  b a Department of Environmental Engineering, Atat € uu rk University, Erzurum 25240, Turkey b Department of Biology, Atat € uu rk University, Erzurum 25240, Turkey Abstract Biosorption of chromium(VI) on to cone biomass of   Pinus sylvestris  was studied with variation in the parameters of pH, initialmetal ion concentration and agitation speed. The biosorption of Cr(VI) was increased when pH of the solution was decreased from7.0 to 1.0. The maximum chromium biosorption occurred at 150 rpm agitation. An increase in chromium/biomass ratio caused adecrease in the biosorption efficiency. The adsorption constants were found from the Freundlich isotherm at 25   C. The conebiomass, which is a readily available biosorbent, was found suitable for removing chromium from aqueous solution.   2002 Published by Elsevier Science Ltd. Keywords:  Biosorption; Chromium(VI); Heavy metal; Wastewater treatment; Cone;  Pinus sylvestris 1. Introduction Environmental pollution due to developments intechnology is one of the most significant problems of this century. Among all heavy metals, copper, chro-mium and zinc ingestion beyond permissible quanti-ties causes various chronic disorders in human beings(Prakasham et al., 1999). Current treatment processesfor metal-containing wastewaters are reported to exhibitreduced efficiency at low concentrations. Industry hasbegun to seek alternative ways of treating wastewater.Chromium in industrial waste is primarily present in theform of hexavalent Cr(VI) as chromate (CrO 2  4  ) anddichromate (Cr 2 O 2  7  ). The wastewaters of industrial dyesand pigments, film and photography, galvanometry andelectric, metal cleaning, plating and electroplating, lea-ther and mining contain undesirable amounts of chro-mium(VI) according to the water standards (Aksu et al.,1990; McGrath and Smith, 1990). Potable waters con-taining more than 0.05 mgl  1 chromium are consideredto be toxic (Vishwanatham, 1997). Conventional meth-ods for removing Cr(VI) ions from wastewater includechemical reduction, electrochemical treatment, ion ex-change and evaporative recovery. Such processes may beineffective or extremely expensive when initial heavymetal concentrations are in the range of 10–100 gm  3 (Aksu et al., 1990). To compete with conventional pro-cedures, new methods must be economically viable aswell as successful in contaminant removal (Grau andBisang, 1995; Dean and Tobin, 1999; Denizli et al.,1999). Biosorption, an alternative process, is the uptakeof heavy metals from aqueous solutions by biologicalmaterials. This novel approach is competitive, effectiveand cheap (Bayhan et al., 2001; Volesky, 2001). Bio- sorption of metals by biomass has been much exploredin recent years. Different form of inexpensive, non-livingplant material such as rice husk (Khalid et al., 1998),sawdust (Holan and Volesky, 1995), pine bark andcanola meal (Al-Asheh and Duvnjuk, 1998; Al-Ashehet al., 1998) have been widely investigated as potentialbiosorbents for heavy metals.Cone biomass was a waste itself and a readily avail-able biosorbent. The ovulate cone is the well-knowncone of the  Pinus  and other conifers. Each cone is com-posed of an axis upon which are borne, in a spiralfashion, a large number of woody scales. Two megaspo-rangia, in ovules, develop on the upper surface of eachscale. Upon maturity they become seeds; the ovulatecone is, therefore, a seed-bearing cone. The scales of the mature cone are composed of epidermal and scle-renchyma cells which contain cellulose, hemicellulose, Bioresource Technology 85 (2002) 155–158 * Corresponding author. Tel.: +90-442-231-23-29; fax: +90-442-233-69-61. E-mail address: (A. Cakici).0960-8524/02/$ - see front matter    2002 Published by Elsevier Science Ltd.PII: S0960-8524(02)00086-X  lignin, rosin and tannins in their cell walls (Robbinset al., 1957; Sakagami et al., 1992).In this study, the use of ovulate cone biomass of  Pinus sylvestris  as a biosorbent for Cr(VI) from artificialwastewaters was studied to determine the constants of the adsorption isotherm relation. 2. Methods  2.1. Biosorbent preparationP. sylvestris  ovulate cones were used in this investi-gation. Cones were collected in May and June of 2001.They were dried at 80   C for 24 h, ground in a mortarto a very fine powder and sieved through a 400-meshcopper sieve.  2.2. Biosorption studies 2827 g of K 2 Cr 2 O 7  was dissolved in one liter of dis-tilled water and used as stock solution. The concentra-tion of Cr(VI) in the stock solution was measured, andthe solution was used for further experimental solutionpreparation. The pH of solution was adjusted with HCland NH 3  solutions after the addition of the biosorbent.A known quantity of the dried biosorbent was addedinto the metal bearing solution of a given concentrationin Erlenmeyer flasks. The biosorption medium wasstirred at constant speed for 2 h at 25   C. The sampleswere taken at definite time intervals and were filteredimmediately to remove biomass and the Cr(VI) inthe remaining solution was analysed. The unadsorbedCr(VI) in the adsorbtion medium was determined with aspectrophotometer (Shimadzu UV-160) at a wavelengthof 540 nm, using diphenylcarbazide as a complexingagent (American Public Health Association, 1986). Zetapotential were measured with a Zeta-Meter (ZETA-METER 3 : 0 þ 542, USA). 3. Results and discussion 3.1. Effect of pH on biosorption capacity The biosorptions on the cone biomass of Cr(VI) from50 mgl  1 chromium solutions at various controlled pHvalues are presented in Fig. 1. The uptake of Cr(VI)increased with a decrease in the solution pH. The bio-sorption efficiency increased from 20.3% at pH 7.0 to100.0% at pH 1.0. The highest biosorption efficiency wasobtained at pH 1.0–2.0. Therefore, the following ex-perimental runs were performed at pH 1.0. The increasein Cr(VI) removal with decreasing pH of the solutionwas also observed by Dean and Tobin (1999) for peat,Prakasham et al. (1999) and Kapoor et al. (1999) forfungal biomass and Sag and Kutsal (1989) for bacteriumbiomass. At lower pH values (1.0–1.5), H 2 CrO 4  is theexistent species and, HCrO  4  the predominant speciesbetween pH 1.5 and 4.0. H 2 CrO 4  decreases with in-creasing pH (Benefield et al., 1982, Dean and Tobin,1999). The pH dependence of the metal uptake could belargely related to the various functional groups on thecone cell surface and also on the metal solution chem-istry. Many biosorbents with surfaces consisting mainlyof acidic polysaccharides, maintain an ability to com-plex heavy metals (Sag and Kutsal, 1989).Zeta potential values of the cone biomass were de-termined at various pH to deionized water. It was foundthat zeta potential values of cone biomass were ap-proximately the same as those of the deionized waterand chromium solution. The zeta potential values couldnot be measured due to the high ionic strength at pH1.0–2.0, but it was considered that these values wereslightly positive. The same pH binding profiles (Fig. 2)for Cr(VI) solution could have been due to the nature of chemical interaction of Cr(VI) with the cone biomasscells and related to the isoelectric point of cells, whichwould be pH 2.7 for cone biomass. Above this, thecells would have a negative charge. As the pH is low-ered, however, the overall surface charge on the cellswill become positive and the interaction of the chro-mium(VI) with the cells will be primarily electrostatic innature. As the pH increased, the overall surface chargeon the cells could become negative and biosorption de-creased (Aksu and Akpinar, 2001). But the detailedmechanism of this adsorption needs to be investigated(such as ion exchange, complex formation and physico-chemical forces). Fig. 1. Effect of pH on Cr(VI) biosorption efficiency. (Initial metalconcentration  ð C  o Þ¼ 50 mgl  1 , temperature  ð T  Þ¼ 25   C, biomassdose  ð m Þ¼ 1 gl  1 , agitation speed  ð rpm Þ¼ 150, contact time  ð t  Þ¼ 2 h.)156  H. Ucun et al. / Bioresource Technology 85 (2002) 155–158  3.2. Biosorption time The effect of the contact time on biosorption of Cr(VI) on cone biomass was studied at the previousoptimum condition (Fig. 3), where the biosorption oc-curred in two steps; an initial fast step which lasted for30 min (shortest time measured) followed by a slowersecond phase which continued until the end of experi-mental period. The equilibrium was reached within 2 h.Further increase in contact time did not show an in-crease in biosorption. 3.3. Effect of initial Cr(VI) concentration on biosorption The biosorption of Cr(VI) was carried out at differentinitial Cr(VI) ion concentrations ranging from 50 to 300mgl  1 . The amount of Cr(VI) adsorbed on the biomass(mgg  1 ) increased with the initial concentration of themetal ions. An increase in the chromium/biomass ratiocaused a decrease in the biosorption efficiency (Table 1).These results may be explained by the fact that at lowCr(VI) concentrations the ratio of the sorptive surface of the cone biomass to total Cr(VI) availability is high,hence, all Cr(VI) may be interacted with biosorbent andremoved.Study of the isotherms indicates the adsorption ca-pacity of material for the removal of chromium from thesolution at constant conditions. Therefore, the data wereanalysed for the Freundlich isotherm, the FreundlichEquation has the general form of  q ¼  K  f  C  1 = n e  ð 1 Þ where  q  is the uptake of metal per unit weight of bio-sorbent,  C  e  the equilibrium (residual) concentration of metal ion in solution,  K  f  ,  n  are the characteristic con-stants. The data are usually fitted to the logarithmicform of the equation,log q ¼ log  K  f   þ 1 = n log C  e  ð 2 Þ The adsorption isotherm seemed to describe well thebiosorption experimental data of Cr(VI) with a corre-lation coefficient of ( r ) 0.9822. The biosorption capacity(  K  f  ) and the biosorption intensity (1 = n ) were estimatedfrom the intercept and the slope of the Freundlich iso-therm. The adsorption constants and  q  were comparedwith those of other adsorbents reported in the literature,as listed in Table 2. The magnitude of   K  f   and  n  showseasily separation of heavy metal ion from wastewaterand high adsorption capacity. 3.4. Effect of agitation speed  Biosorption studies were carried out in a shaker atpH 1.0 using a Cr(VI) solution of 150 mgl  1 . The agi-tation speed varied from 100 to 240 rpm. The percentageof biosorption increased at all different agitation speedconditions (100–240), but the Cr(VI) removal rate wasmaximum at 150 rpm. Fig. 2. Relation between zeta potential and pH. ( C  o  ¼ 150 mgl  1 , T   ¼ 25   C,  m ¼ 1 gl  1 , rpm ¼ 150,  t  ¼ 2 h.)Fig. 3. Effect of contact time on bisorption. ( C  o  ¼ 150 mgl  1 ,pH ¼ 1 : 0,  T   ¼ 25   C,  m ¼ 1 gl  1 , rpm ¼ 150.)Table 1Effect of inital Cr(VI) concentration on biosorption C  o  C  e  Cr adsorbed on thebiomass ( q ) (mgg  1 )Biosorptionefficiency (%)50 0.00 50.00 100.00100 10.63 89.37 89.37150 27.79 122.20 81.47200 43.52 156.48 78.24250 77.50 172.50 69.00300 98.19 201.80 67.26 m ¼ 1 gl  1 ,  T   ¼ 25   C, rpm ¼ 150, pH ¼ 1 : 0,  t  ¼ 2 h. H. Ucun et al. / Bioresource Technology 85 (2002) 155–158  157  4. Conclusions The potential of using cone biomass of   P. sylvestris for the removal of chromium was demonstrated. Thebiomass exhibited high adsorption capacity. The bio-sorption was rapid with 84% of the total adsorptionoccurring in 2 h at  C  o  ¼ 150 mgl  1 and  m ¼ 1 gl  1 . ThepHoftheaqueousphasestronglyaffected theadsorptioncapacity, with the highest capacity achieved at pH 1.0. References Al-Asheh, S., Duvnjuk, Z., 1998. Binary metal sorption by pine bark:study of equilibria and mechanisms. Separation Science andTechnology 33 (9), 1303–1329.Al-Asheh, S., Lamarche, G., Duvnjuk, Z., 1998. Investigation of copper sorption using plant materials. Water Quality ResearchJournal of Canada 33 (1), 167–183.American Public Health Association, 1986. Standard Methods forExamination of Water and Wastewater, sixteenth ed. AmericanPublic Health Association, Washington, DC.Aksu, Z., Akpinar, D., 2001. Competitive biosorption of phenol andchromium(VI) from binary mixtures onto dried anaerobic acti-vated sludge. Biochemical Engineering Journal 7, 183–193.Aksu, Z., Sag, Y., Kutsal, T., 1990. A comparative study of theadsorption of chromium(VI) ions to  C. vulgaris  and  Z. ramigera .Environmental Technology 11, 33–40.Bayhan, Y.K., Keskinler, B., Cakici, A., Levent, M., Akay, G., 2001.Removal of divalent heavy metal mixtures from water by Saccharomyces cerevisiae  using crossflow microfiltration. WaterResearch 35, 2191–2200.Benefield, L.D., Judkins Jr., J.F., Weand, B.L., 1982. ProcessChemistry for Water and Wastewater Treatment, EnglewoodCliffs, NJ, pp. 433–435.Cetinkaya Donmez, G., Aksu, Z., Ozturk, A., Kutsal, T., 1999. Acomparative study on heavy metal biosorption characteristics of some algae. Process Biochemistry 34, 885–892.Dean, S.A., Tobin, J.M., 1999. Uptake of chromium cations andanions by milled peat. Resources Conservation and Recycling 27,151–156.Denizli, A., Say, R., Testereci, H.N., Arica, M.Y., 1999. Procein blueMX-36-attached-poly (HEMA) membranes for copper, arsenic,cadmium and mercury adsorption. Separation Science and Tech-nology 34, 2369–2381.Grau, J.M., Bisang, J.M., 1995. Removal and recovery of mer-cury from chloride solutions by contact deposition on ironfelt. Journal of Chemical Technology and Biotechnology 62, 153– 158.Holan, Z.R., Volesky, B., 1995. Accumulation of cadmium, lead andnickel by fungal and wood biosorbents. Applied Biochemistry andBiotechnology 53, 133–146.Kapoor, A., Viraraghavan, T., Cullimore, D.R., 1999. Removal of heavy metals using the fungus  Aspergillus niger . BioresourceTechnology 70 (1), 95–104.Khalid, N., Rahman, A., Ahmad, S., Kiani, S.N., Ahmed, J., 1998.Adsorption of cadmium from aqueous solutions on rice husk. Plantand Soil 197, 71–78.McGrath, S.P., Smith, S., 1990. Chromium and nickel. In: Alloway,B.J. (Ed.), Heavy Metals in Soils. John Wiley, New York, pp. 125– 150.Prakasham, R.S., Merrie, J.S., Sheela, R., Saswathi, N., Ramakrisha,S.V., 1999. Biosorption of chromium(VI) by free and immobilized Rhizopus arrhizus . Environmental Pollution 104, 421–427.Robbins, W.W., Weier, T.E., Stocking, C.R., 1957. In: Botany AnIntroduction to plant Science, second ed. John Wiley and SonsInc., New York, pp. 495–496.Sag, Y., Kutsal, T., 1989. Application of adsorption isotherms tochromium adsorption on  Z. ramigera . Biotechnology Letters 11,141–144.Sakagami, H., Takeda, M., Kawazoe, Y., Nagata, K., Ishihama, A.,Ueda, M., Yamazaki, S., 1992. Anti-influenza virus activity of alignin fraction from cone of   pinus parviflora . Sieb. et Zucc., In Vivo,Athens, Greece, 6, 5, 491–495.Sudha Bai, R., Abraham, T.E., 2001. Biosorption of Cr(VI) fromaqueous solution by  Rhizopus nigrificans . Bioresource Technology79, 73–81.Vishwanatham, M., 1997. In: Anjaneyulu, Y. (Ed.), Proc. Int. Conf.Indus. Pollution and Control Technologies, Hyderabad, pp. 491– 498.Volesky, B., 2001. Detoxificiation of metal  ––  bearing effluents. Bio-sorption for the next centry. Hydrometallurgy 59, 203–216.Table 2The Freundlich isotherm constants and  q  values for Cr(VI) of variousadsorbentsAdsorbent  K   1 = n  q  Reference Rhizopusarrhizus 10.99 0.18 23.88 Prakasham et al.(1999) Rhizopusnigrificans 12.06 3.24 99.00 Sudha Bai andAbraham (2001) Chlorellavulgaris 0.48 1.26 33.80 Cetinkaya Donmezet al. (1999) Scenedesmusobliquus 0.68 1.42 30.20 Cetinkaya Donmezet al. (1999) Synechocystis sp.1.54 1.40 39.00 Cetinkaya Donmezet al. (1999)Anaerobic ac-tivated sludge3.62 1.26 195.30 Aksu and Akpinar(2001)Cone biomass 38.38 0.35 201.81 This study158  H. Ucun et al. / Bioresource Technology 85 (2002) 155–158
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