膨润土对溶液中阴离子态Cr(Ⅵ)的吸附特性及机理研究  

The adsorption characteristics and the mechanism of bentonite on anionic Cr(Ⅵ) in aqueous solutions

作　　者：王倩[1,2] 王亚萍[1,3] 由晓芳[1] 王志明 李琳[1] 邱俊[1] 吕宪俊[1] 曹晓强[1] WANG Qian;WANG Yaping;YOU Xiaofang;WANG Zhiming;LI Lin;QIU Jun;LYU Xianjun;CAO Xiaoqiang(College of Chemical and Environmental Engineering,Shandong University of Science and Technology,Qingdao 266590,China;School of Environmental Science and Engineering,Shandong University,Ji nan 251000,China;College of Environmental Science and Engineering,Nankai University,Tianjin 300350,China)

机构地区：[1]山东科技大学化学与环境工程学院,山东青岛266590 [2]山东大学环境科学与工程学院,山东济南251000 [3]南开大学环境科学与工程学院,天津300350

出　　处：《中国矿业》2018年第8期131-138,共8页China Mining Magazine

基　　金：国家自然科学基金项目资助(编号:51204104;51474140;51674161;51774200);山东省优秀中青年科学家科研奖励基金资助(编号:BS2012CL026);山东省重点研发计划资助(编号:2016GSF116013)

摘　　要：本文研究了阴离子态Cr(Ⅵ)在膨润土中的吸附行为,并对吸附机理进行了分析。结果表明,pH=2~12,膨润土表面ζ电位均为负值,随着溶液pH值提高,膨润土对Cr(Ⅵ)的吸附效率明显下降。膨润土对Cr(Ⅵ)的吸附符合准2级动力学模型,吸附传质速率主要受膜扩散过程影响。Freundlich方程能够更精确的描述膨润土对Cr(Ⅵ)的吸附行为。热力学分析结果说明膨润土吸附Cr(Ⅵ)是一个自发的吸热反应,低pH值条件下少量Cr(Ⅵ)会发生还原反应从而生成Cr^(3+),导致部分Cr(Ⅵ)以Cr^(3+)的形式被去除。综合分析认为Cr(Ⅵ)的初始浓度较低时,内界表面配合是主要去除机制;初始浓度较高时,同时存在物理吸附以及内界表面配合作用。The adsorption behavior and mechanisms of anionic heavy metal Cr（VI） on purified bentonite have been investigated.The results showed that the surface zeta potential of bentonite was negative at pH=2-12.The adsorption efficiency was decreased with the increase of the solution pH value.The adsorption process followed the pseudo-second order kinetic model and Freundlich isotherm very well,and adsorption rate is mainly influenced by the membrane diffusion.The thermodynamic parameters indicated that the adsorption process of Cr（Ⅵ） on bentonite was an endothermic and spontaneous process.A small amount of Cr （Ⅵ） can be converted to Cr 3＋ by reducing the reaction at low pH value range,and then the ion exchange and surface complexation between Cr 3＋ and bentonite partly contributed to Cr（Ⅵ） adsorption on bentonite.At low initial concentration of Cr（Ⅵ）,the adsorption of Cr（Ⅵ） was mainly dominated by inner-sphere surface complexation,whereas physical adsorption was another adsorption mechanism at high initial concentration of Cr（Ⅵ）.

关 键 词：膨润土 铬 吸附 表面配合 

分 类 号：TQ424[化学工程] X703[环境科学与工程—环境工程]