Study On The Preparation Of Biosorbents Orange Peels And Biosorption Of Heavy Metal Pb～(2+) And Cu～(2+) Ions

Enhanced industrial activity during recent decades has led to the discharge ofunprecedented volumes of wastewater, which is a serious cause of environmental degradation.Aqueous heavy metal pollution represents an important environmental problem due to itstoxic effects and accumulation throughout the food chain. The main sources of heavy metalpollution are mining, milling and surface finishing industries, discharging a variety of toxicmetals such as Cu, Zn, Cd and Pb into the environment. Conventional technologies such aschemical precipitation, oxidation/reduction, ion exchange, electrolysis or membrane filtrationhave been used for the removal of heavy metals from the environment. These methods are ingeneral expensive and potentially risky due to the possibility of the generation of hazardousby-products. On the other hand, these technologies are most suitable in situations where theconcentrations of the heavy metal ions are relatively high. They are either ineffective orexpensive when heavy metals are present in the wastewater at low concentrations, or whenvery low concentrations of heavy metals in the treated water are required. Large volumes ofindustrial heavy metal-bearing wastewaters require efficient and very cost-effective treatment.Biosorption appears to offer a technically feasible and economically attractive approach.In this paper, preparation of orange peel cellulose biosorbents and its biosorptionbehaviors of copper and lead ions are studied. Effects of alkaline saponification, differentconcentrations of citric acid and different temperatures on the adsorption characters ofbiosorbents are investigated. The influences of pH, shaking time and s/l ratio on thebiosorption of copper and lead ions are also discussed. As can be seen from the experimentalresults that biosorption equilibriums were rapidly established in about one h and adsorption ofcopper ion by using SOP, 0.6SCA5 and 0.1SCA8 could be explained as pseudo-first-orderkinetic process. The copper and lead adsorption were strictly pH dependent, and maximumremoval of copper and lead ions were observed at pH 5.2.and 5.3 respectively. The resultsshowed that the order of maximum uptake capacity of copper ion was: 0.6SCA8 >0.6SCA5>0.6SCA2 > 0.1SCA8 >0.1SCA5 >0.1SCA2 >SOP >0.1CA >AOP >0.6CA >OP. For lead ion,the order of maximum uptake capacity was: 0.6SCA8>0.1SCA8>0.6SCA5 >0.1SCA5 >0.6SCA2>SOP>0.1SCA2>0.1CA>AOP>0.6CA>OP. And the maximum uptake capacities ofcopper and lead were obtained as 1.22 and 1.23 molkg^-1 respectively. A comparison ofdifferent isotherm models revealed that Langmuir and the combination of Langmuir andFreundlich (L-F) isotherm model fitted the experimental data best.