Uluozlu Ozgür Dogan, Sari Ahmet, Tuzen Mustafa, Soylak Mustafa
Department of Chemistry, Gaziosmanpasa University, 60250 Tokat, Turkey.
Bioresour Technol. 2008 May;99(8):2972-80. doi: 10.1016/j.biortech.2007.06.052. Epub 2007 Aug 21.
The biosorption characteristics of Pb(II) and Cr(III) ions from aqueous solution using the lichen (Parmelina tiliaceae) biomass were investigated. Optimum biosorption conditions were determined as a function of pH, biomass dosage, contact time, and temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherm of the metal ions by P. tiliaceae biomass. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The monolayer biosorption capacity of P. tiliaceae biomass for Pb(II) and Cr(III) ions was found to be 75.8 mg/g and 52.1mg/g, respectively. From the D-R isotherm model, the mean free energy was calculated as 12.7 kJ/mol for Pb(II) biosorption and 10.5 kJ/mol for Cr(III) biosorption, indicating that the biosorption of both metal ions was taken place by chemical ion-exchange. The calculated thermodynamic parameters (delta G degrees , delta H degrees and delta S degrees ) showed that the biosorption of Pb(II) and Cr(III) ions onto P. tiliaceae biomass was feasible, spontaneous and exothermic under examined conditions. Experimental data were also tested in terms of biosorption kinetics using pseudo-first-order and pseudo-second-order kinetic models. The results showed that the biosorption processes of both metal ions followed well pseudo-second-order kinetics.
研究了利用地衣（蒂氏梅衣）生物质从水溶液中吸附Pb(II)和Cr(III)离子的特性。确定了最佳生物吸附条件与pH值、生物质用量、接触时间和温度的函数关系。应用Langmuir、Freundlich和Dubinin-Radushkevich（D-R）模型描述蒂氏梅衣生物质对金属离子的生物吸附等温线。Langmuir模型比Freundlich等温线更能拟合平衡数据。发现蒂氏梅衣生物质对Pb(II)和Cr(III)离子的单层生物吸附容量分别为75.8 mg/g和52.1mg/g。根据D-R等温线模型，计算得出Pb(II)生物吸附的平均自由能为12.7 kJ/mol，Cr(III)生物吸附的平均自由能为10.5 kJ/mol，表明两种金属离子的生物吸附均通过化学离子交换进行。计算得到的热力学参数（ΔG°、ΔH°和ΔS°）表明，在研究条件下，Pb(II)和Cr(III)离子在蒂氏梅衣生物质上的生物吸附是可行的、自发的且放热的。还使用伪一级和伪二级动力学模型对生物吸附动力学方面的实验数据进行了测试。结果表明，两种金属离子的生物吸附过程均很好地遵循伪二级动力学。
