陕西省主要土壤磷吸附动力学和热力学特征研究

Kinetic and Thermodynamic Characteristics of Phosphate Adsorption by Soil

采用３２Ｐ同位素稀释法测定了陕西省４种主要农业土壤添加磷２ｈ后的吸附动态，并将绝对反应速率理论移植用于磷吸附热力学特征的研究。结果表明，土壤磷吸附的动力学过程符合Ｅｌｏｖｉｃｈ方程和一级反应方程；磷吸附的温度商Ｑ１０为１０９左右，磷吸附的活化能为２６～７６ｋＪ／ｍｏｌ，说明磷加入土壤２ｈ后的吸附过程是一个物理过程；同一条件下磷吸附的热力学函数—吸附活化焓变、活化熵变和活化自由能变均为黄绵土＜黑垆土＜土娄土＜黄褐土，说明磷吸附所需克服的能障及所需的热能随质地变粘依次增大，吸附速度及吸附使体系有序度增加幅度依次减小。

The phosphate adsorption by four type agricultural soils of Shaanxi Province under different temperature and varying time were measured by the dilution method using 32 P labelled KH 2PO 4 solution Four kinetic models were used to fit the dynamic process of phosphate adsorption by the soils It was found that Elovich equation or first order equation was the best model described the process The parameters, i e adsorption activation energy, activation entropy, activation enthalpy and activation free energy were calculated by the absoulte reaction rate theory The results showed that these parameters changed in order as loessal soil<black lu soil<lou soil<yellow cinnamon soil, which indicated that the force to be overcome during the adsorption increased and the adsorption rate decreased as well as the disorder of system due to adsorption increased successively in the four soils after phosphate was added to soil two hours later