土壤吸附草甘膦的热力学研究

Study on Thermodynamics of Soil Adsorbing Glyphosate

[目的]为草甘膦的环境污染防治提供理论依据。[方法]研究了在298、303、308K温度下草甘膦的吸附平衡时间和吸附等温线的测定。[结果]草甘膦在水-土两相中分配6 h内达到平衡。Freundlich吸附等温线拟合得到的相关系数均大于Langmuir吸附等温线拟合得到的相关系数,适合描述草甘膦在土壤中的吸附行为。土壤吸附草甘膦的吸附过程是吸热吸附,温度升高有利于吸附。吸附过程是自发吸附过程,随着温度的升高,吸附过程自发趋势增大,但变化较小。吸附过程是熵增加过程。温度低时,土壤对草甘膦的吸附量小,土壤表面的混乱程度较大;温度高时,土壤对草甘膦的吸附量较大,土壤表面的混乱度较小。[结论]土壤吸附草甘膦的过程是一种自发吸热的吸附过程。

[Objective ] The study was to provide the theoretical basis for environmental pollution control. [ Method ] The adsorption equilibrium time and adsorption isotherm of glyphosate were detected under the temperature of 298 K, 303 K and 308 K. [ Result]The glyphosate in water-soil two phases got balance in 6 h. The correlation coefficient of adsorption isotherm fitting Freundlich were all bigger than that of fitting Langmuir and it was suitable to describe the adsorption behavior of glyphosate in soil. The process of soil adsorbing glyphosate was an endothermic adsorption process, so high temperature was beneficial to adsorption. The adsorption process was a spontaneous process. The spontaneous trend increased with the rising temperature, but the change was very small. The adsorption process was an increasing process of entropy. When the temperature was low, the adsorption quantity of soil to glyphosate was small and the confusion degree of soil surface was bigger. When the temperature was high, the adsorption quantity of soil to glyphosate was big and the confusion degree of soil surface was smaller. [ Conelusion] The process of soil adsorbing glyphosate was an spontaneous endothermic adsorption process.