作　　者： ; ; ; ; ;

机构地区： 湖南大学环境科学与工程学院

出　　处： 《环境工程学报》 2009年第5期857-860,共4页

摘　　要： 采用批量平衡法研究了海带对镉的吸附的动力学与热力学,并采用Lagrange假一级动力学方程、假二级动力学方程、Langmuir等温线方程、Freundlich等温线方程以及Dubimim-Radushkevich等温线方程对实验数据进行了拟合。结果表明,在4种温度下海带对镉的吸附率均随吸附反应时间增加而增大,在60 min时达到最大,此后基本保持不变,随着温度由20℃升高至50℃,其最大吸附率呈下降趋势,由90.2%降至77.5%;海带对镉的吸附动力学符合Lagrange假二级动力学方程;海带对镉的吸附热力学符合Langmuir等温线方程和Dubimim-Radushkevich等温线方程,表明吸附主要发生在海带表面的活性区位,属于单分子层吸附,其吸附平均活化自由能E为11.4 kJ/mol,表明该吸附过程为化学吸附,在4种温度下吉布斯自由能变化量ΔG°均为负值,吸附焓变ΔH°也为负值,表明海带对镉的吸附为放热反应,能自发进行。 A batch method was used to investigate the kinetics and thermodynamics of cadmium（ Ⅱ ） biosorption onto Laminaria japonica, where the Lagrangian pseudo-first-order and pseudo-seconder-order kinetic model, Langmuir, Freundlich and Dubinin-Radushkevich（D-R） isotherm models were applied to simulate the experimental parameters. The results show that the efficiency of biosorption is increased with the time of reaction and the maximum efficiency is attained at 60 min. The maximum efficiency of biosorption is decreased from 90.2% to 77.5% when the temperature is changed from 20 ℃ to 50 ℃. The biosorption of cadmium（ Ⅱ ） onto Laminaria japonica is found to follow pseudo-seconder-order kinetic model well. On the other hand,the biosorption of cadmium （ Ⅱ ） onto Laminaria japonica follows Langmuir and D-R isotherm models well, which indicates that the biosorption taken place at the functional groups/binding sites on the surface of the biosorbent which is regarded as monolayer biosorption. From the D-R isotherm model, the mean free energy is calculated as 11.4 k J/ mol, indicating that the biosorption of cadmium （ Ⅱ ） is taken place by chemisorption. The calculated thermodynamic parameters （△G^O,△H^o and △S^o） show that the biosorption of cadmium （ Ⅱ ） onto Laminariajaponica is feasible, spontaneous and exothermic.

关 键 词： 海带 镉 吸附动力学 热力学

领　　域： [理学] [理学]