Division of Radioactivity Measurement, Cekmece Nuclear Research and Training Centre, 34303, Halkali, Istanbul, Turkey.
Institute of Environmental Sciences, Bogazici University, 34342, Bebek, Istanbul, Turkey.
Environ Sci Pollut Res Int. 2018 Feb;25(4):3020-3029. doi: 10.1007/s11356-015-4103-9. Epub 2015 Jan 24.
Uptake of radioactive metal species from soils and solutions by clay particles could be a treatment option due to simplicity of operation and economic cost. In this concern, adsorption behavior of Cs or Co onto bentonite as a function of contact time, pH, initial metal concentration, ionic strength, and temperature was studied by batch adsorption technique. Adsorption isotherm data were interpreted by Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models. Bentonite exhibited maximum adsorption capacity of 83.3 mg g for Cs and 15.9 mg g for Co. Presence of humic acid (HA) as a representative model of organic matter did not significantly affect the adsorption capacity of bentonite for Cs, whereas it increased the adsorption capacity of bentonite for Co. Thermodynamic parameters, standard enthalpy (ΔH°), standard entropy (ΔS°), and standard free energy (ΔG°) were determined through batch adsorption experiments performed at four different temperatures of 288, 298, 318, and 338 K. Co adsorption onto bentonite showed an endothermic reaction (ΔH° = 13.6 kJ mol) whereas Cs adsorption displayed an exothermic nature (ΔH° = -4.65 kJ mol). Negative values of ΔG° and positive values of ΔS° indicated the feasibility and spontaneous nature of adsorption processes and more disordered form after adsorption.
由于操作简单和经济成本低，粘土颗粒从土壤和溶液中摄取放射性金属物种可能成为一种处理选择。在这方面，通过批量吸附技术研究了 Cs 或 Co 与膨润土作为接触时间、pH 值、初始金属浓度、离子强度和温度函数的吸附行为。吸附等温线数据通过 Langmuir、Freundlich 和 Dubinin-Radushkevich（D-R）等温模型进行解释。膨润土对 Cs 的最大吸附容量为 83.3 mg g，对 Co 的最大吸附容量为 15.9 mg g。腐殖酸（HA）作为有机物质的代表性模型的存在并没有显著影响膨润土对 Cs 的吸附能力，而增加了膨润土对 Co 的吸附能力。通过在 288、298、318 和 338 K 的四个不同温度下进行的批量吸附实验，确定了热力学参数、标准焓（ΔH°）、标准熵（ΔS°）和标准自由能（ΔG°）。Co 吸附到膨润土上是一个吸热反应（ΔH°= 13.6 kJ mol），而 Cs 吸附表现出放热性质（ΔH°= -4.65 kJ mol）。ΔG°的负值和ΔS°的正值表明吸附过程的可行性和自发性，以及吸附后更无序的形式。
