腐殖酸对苯并三唑的吸附动力学及热力学研究

Kinetics and Thermodynamics of Benzotriazole Adsorption on Humic Acids

HA（腐殖酸）是土壤和沉积物中有机质的重要组成部分，能在很大程度上影响有机污染物的环境行为和毒理效应．采用批量平衡法研究了BT（苯并三唑）在HA上的吸附动力学、等温吸附和吸附热力学等内容，结果表明：拟二级动力学能较好地描述BT在HA上的吸附行为，吸附过程分为快速吸附阶段和慢速吸附阶段，但主要以快速吸附为主；0～40min为快速吸附阶段，吸附总量占平衡吸附量的89．0％以上．吸附等温线较好地符合Freundlich模型，R^2均在0．9996以上．初始ρ（BT）为300．0mg／L时，温度由288．15K升至308．15K，吸附量从15．70g／kg降至11．58g／kg，减少了26．24％．此外，△H^0（吸附焓变）为-30．19kJ／mol，说明吸附过程为放热反应；△G^0（吉布斯自由能变）小于零，说明反应是自发的．吸附反应的Et（活化能）为19．35kJ／mol，表明吸附属于物理吸附．

Humic acids （HA）, which can affect the environmental behaviors and toxicological effects of organic contaminants, are a critical fraction of natural organic matters （NOM） in soil and/or sediment. A clear understanding of sorption of organic contaminations to humic acids would be helpful in determining their sorption mechanisms in soil and/or sediment. Using batch equilibrium method, the kinetics and thermodynamics of ben zotriazole （BT） adsorption on HA were investigated. The results show that the kinetic data were well described by the pseudo second-order kinetic model. The adsorption was rapid in the beginning and then was followed by a slowly increasing period. BT was quickly adsorbed during the first 40 minutes, and the total amount of adsorbed adsorbate reached above 89.0 % of the sorption amount at equilibrium for all the treatments. The adsorption isotherms could be described by Freundlich models with high R2 values of 0. 9996-0. 9999. The solution temperature was negatively correlated with the adsorption rate. When the temperature increased from 288.15 K to 308.15 K, the amount of adsrobate adsorbed decreased from 15.70 g/kg to 11.58 g/kg, Furthermore, during the adsorption process, △H^0 was -30. 19 kJ/mol, indicating that the adsorption was exothermic. The negative AGO suggested that the adsorption process was spontaneous. The E, parameter was obtained by the Arrhenius Equation; the activation energy in this study was 19.35 kJ/mol, indicating that BT adsorption by HA is a typical physicals adsorption.