铵型斜发沸石脱除Pb^(2+)离子的热力学研究

Thermodynamics Research on Removal of Pb^(2+) Ions from NH_4^+-Clinoptilolite

通过实验测定铵型天然斜发沸石对铅离子全交换容量为80.07mmol/100g沸石。用Langmuir吸附等温方程和Freundlich吸附等温方程拟合了吸附等温数据,绘制NH4+-Pb2+离子交换等温线以及Kielland图。依据热力学平衡原理,计算出该过程的焓、吉布斯自由能和熵变化。研究表明天然斜发沸石NH4+-Pb2+离子交换过程可自发进行,且为吸热反应,高温有利于铅离子的交换。

The cation exchange capacity of the Pb^2＋ on NH4^＋-clinoptilolite is 80.07 mmol/100g. The adsorption isotherms datas was fited with Langmuir equation and Frcundlich equation. The NH4^＋-Pb〉 ion exchange isotherm and Kielland diagram was drawned. According to thermodynamics theory, the enthalpy, Gibbs free energy and entropy were figured out. The result showed that the process took place spontaneously, which was an endothermic reaction. The high temperature is advantageous to the selectivity of NH4^＋-clinoptilolite to exchange of Pb^2＋.