天然和CPB改性沸石对Hg^2＋的吸附特征

通过静态实验研究溴代十六烷基吡啶（CPB）改性沸石和天然沸石对废水中Hg^2＋的吸附特性，探讨了吸附动力学、吸附平衡和吸附热力学机制。研究表明：Langmuir方程能较好地描述2种沸石对Hg^2＋的吸附，CPB改性沸石对Hg^2＋的吸附率得到显著提高。实验条件下，改性沸石对Hg^2＋的吸附率从67．5％提高到98．9％，吸附容量从0．521mg／g提高到3．07mg／g。利用准一级动力学方程、假二级动力学方程、颗粒内扩散模型和Elovich方程分别对动力学过程进行拟合，发现2种沸石对Hg^2＋的吸附均满足假二级动力学方程，且离子的颗粒内扩散对整个吸附过程有影响。动力学拟合、D-R方程拟合和热力学研究综合表明：2种沸石对Hg^2＋的吸附既存在化学吸附又存在物理吸附，吸附吉布斯自由能变（△G^0）、焓变（△H^0）、熵变（△S^0）均小于0，反应为自发的放热反应，低温有利于吸附的进行。

Adsorption characteristic of mercury （ll） on natural and CPB modified zeolite

The adsorption of mercury ions on the natural zeolite and CPB modified zeolite was investigated by conducting a series of batch adsorption experiments. The adsorption kinetics, adsorption equilibrium, thermo- dynamic behavior and mechanism were discussed. Results showed that the equilibrium data of the two kinds of zeolites were well fitted with Langmuir equation. CPB modified zeolite can significantly improve the adsorption of Hg^2＋. The adsorption rate of Hg^2＋ increased from 67.5% to 98.9% , and the adsorption capacity increased from 0. 521 mg/g to 3.07 mg/g under the experimental conditions. Using Pseudo-first-order kinetics, Pseudo-second- order kinetics, Intraparticle diffusion and Elovich equation to simulate the process of dynamic respectively. The kinetic data correlated well with the Pseudo-second-order kinetic model, and the Intraparticle diffusion did have effect on the adsorption. Dynamics fitting, D-R equation fitting and thermodynamics research integrated suggested that both chemical and physical adsorption were existed in the adsorption of Hg^2＋ on two kinds of zeolites. The negative change in free energy （△G^0） , enthalpy （△H^0） and entropy （△S^0） indicated that the adsorption was spontaneous and exothermic. Low temperature made the adsorption easier.