Karthikeyan T, Rajgopal S, Miranda Lima Rose
Department of Chemical Engineering, Alagappa College of Technology, Anna University, Sardar Patel Road, Chennai 600 025, India.
J Hazard Mater. 2005 Sep 30;124(1-3):192-9. doi: 10.1016/j.jhazmat.2005.05.003.
Adsorption capacity of Cr(VI) onto Hevea Brasilinesis (Rubber wood) sawdust activated carbon was investigated in a batch system by considering the effects of various parameters like contact time, initial concentration, pH and temperature. Cr(VI) removal is pH dependent and found to be maximum at pH 2.0. Increases in adsorption capacity with increase in temperature indicate that the adsorption reaction is endothermic. Based on this study, the thermodynamic parameters like standard Gibb's free energy (DeltaG degrees ), standard enthalpy (DeltaH degrees ) and standard entropy (DeltaS degrees ) were evaluated. Adsorption kinetics of Cr(VI) ions onto rubber wood sawdust activated carbon were analyzed by pseudo first-order and pseudo second-order models. Pseudo second-order model was found to explain the kinetics of Cr(VI) adsorption most effectively. Intraparticle diffusion studies at different temperatures show that the mechanism of adsorption is mainly dependent on diffusion. The rate of intraparticle diffusion, film diffusion coefficient and pore diffusion coefficient at various temperatures were evaluated. The Langmuir, Freundlich and Temkin isotherm were used to describe the adsorption equilibrium studies of rubber wood sawdust activated carbon at different temperatures. Langmuir isotherm shows better fit than Freundlich and Temkin isotherm in the temperature range studied. The result shows that the rubber wood sawdust activated carbon can be efficiently used for the treatment of wastewaters containing chromium as a low cost alternative compared to commercial activated carbon and other adsorbents reported.
通过考虑接触时间、初始浓度、pH值和温度等各种参数的影响，在间歇系统中研究了巴西橡胶木锯末活性炭对Cr(VI)的吸附容量。Cr(VI)的去除取决于pH值，发现在pH 2.0时达到最大值。吸附容量随温度升高而增加，表明吸附反应是吸热的。基于这项研究，评估了标准吉布斯自由能（ΔG°）、标准焓（ΔH°）和标准熵（ΔS°）等热力学参数。用拟一级和拟二级模型分析了Cr(VI)离子在橡胶木锯末活性炭上的吸附动力学。发现拟二级模型能最有效地解释Cr(VI)的吸附动力学。不同温度下的颗粒内扩散研究表明，吸附机理主要取决于扩散。评估了不同温度下的颗粒内扩散速率、膜扩散系数和孔扩散系数。用朗缪尔、弗伦德利希和坦金等温线描述了不同温度下橡胶木锯末活性炭的吸附平衡研究。在所研究的温度范围内，朗缪尔等温线比弗伦德利希和坦金等温线拟合得更好。结果表明，与商业活性炭和其他报道的吸附剂相比，橡胶木锯末活性炭作为一种低成本替代品可有效地用于处理含铬废水。
