Kalavathy M Helen, Karthikeyan T, Rajgopal S, Miranda Lima Rose
Department of Chemical Engineering, Alagappa College of Technology, Anna University, Chennai 600 025, India.
J Colloid Interface Sci. 2005 Dec 15;292(2):354-62. doi: 10.1016/j.jcis.2005.05.087. Epub 2005 Jul 22.
Adsorption of Cu(II) from aqueous solution onto H(3)PO(4)-activated carbon using rubber wood sawdust (RSAC) was investigated in a batch system. Kinetic and isotherm studies were carried out by considering the effects of various parameters, such as initial concentration, contact time, pH, and temperature. The optimal pH value for Cu(II) adsorption onto RSAC was found to be 6.0. Thermodynamic parameters such as standard Gibbs free energy (DeltaG(0)), standard enthalpy (DeltaH(0)), and standard entropy (DeltaS(0)) were evaluated by applying the Van't Hoff equation. The thermodynamics of Cu(II) adsorption onto RSAC indicates its spontaneous and exothermic nature. Langmuir, Freundlich, and Temkin isotherms were used to analyze the equilibrium data at different temperatures. The Langmuir isotherm fits the experimental data significantly better than the other isotherms. Adsorption kinetics data were tested using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Kinetic studies showed that the adsorption followed a pseudo-second-order reaction. The initial sorption rate, pseudo-first-order, pseudo-second-order, and intraparticle diffusion rate constants for different initial concentrations were evaluated and discussed. Adsorption mechanism studies revealed that the process was complex and followed both surface adsorption and particle diffusion. The rate-controlling parameter and effective diffusion coefficient were determined using the Reichenberg plot. It was found that the adsorption occurs through film diffusion at low concentrations and at higher concentration the particle diffusion becomes the rate-determining step.
在间歇系统中研究了用橡胶木锯末制备的磷酸活化碳（RSAC）从水溶液中吸附Cu（II）的情况。通过考虑各种参数的影响，如初始浓度、接触时间、pH值和温度，进行了动力学和等温线研究。发现RSAC吸附Cu（II）的最佳pH值为6.0。通过应用范特霍夫方程评估了标准吉布斯自由能（ΔG⁰）、标准焓（ΔH⁰）和标准熵（ΔS⁰）等热力学参数。Cu（II）在RSAC上的吸附热力学表明其具有自发和放热性质。使用朗缪尔、弗伦德利希和坦金等温线分析了不同温度下的平衡数据。朗缪尔等温线对实验数据的拟合明显优于其他等温线。使用拟一级、拟二级和颗粒内扩散模型测试了吸附动力学数据。动力学研究表明吸附遵循拟二级反应。评估并讨论了不同初始浓度下的初始吸附速率、拟一级、拟二级和颗粒内扩散速率常数。吸附机理研究表明该过程复杂，同时遵循表面吸附和颗粒扩散。使用赖兴贝格图确定了速率控制参数和有效扩散系数。发现吸附在低浓度下通过膜扩散发生，在高浓度下颗粒扩散成为速率决定步骤。
