改性膨润土对废水中Cd(Ⅱ)的吸附特征及吸附动力学研究  

Adsorption properties and kinetics of modified bentonite for Cd(Ⅱ) in waste water

作　　者：杨秀敏 王文[1] 谢琼丹 Xiumin YANG;Wen WANG;Qiongdan XIE(Zhai MingguoAcademician Workstation,University of Sanya,Sanya,Hainan 572022,China)

机构地区：[1]三亚学院翟明国院士工作站,海南三亚572022

出　　处：《过程工程学报》2022年第11期1512-1520,共9页The Chinese Journal of Process Engineering

基　　金：海南省自然科学基金资助项目(编号:421MS057);三亚学院人才引进项目(编号:USYRC19-19)。

摘　　要：为探讨改性膨润土对Cd(Ⅱ)的吸附特征及吸附动力学机制,通过吸附实验探讨了pH值、初始浓度和吸附时间对改性膨润土吸附Cd(Ⅱ)的影响。结果表明,盐酸改性膨润土对Cd(Ⅱ)的去除率表现为随溶液pH值升高而升高,而氢氧化钠改性膨润土、膨润土与十二烷基磺酸钠改性膨润土的去除率分别在pH=6和7时达到最大值。膨润土及改性膨润土对Cd(Ⅱ)的去除率随初始浓度的增加而降低,吸附量随平衡浓度增加而增大,并趋向平稳,吸附符合Langmuir方程,吸附为单分子层吸附。膨润土及改性膨润土的吸附反应在240 min内基本达到平衡,吸附动力学分析表明吸附过程更符合准二级动力学模型,吸附过程以化学吸附为主,膨润土及改性膨润土的吸附速率大小依次为K_(2HCl-B)>K_(2NaOH-B)>K_(2B)>K_(2SDS-B),液膜扩散与颗粒内扩散过程均为控速步骤。该研究可为改性膨润土处理含镉废水和修复镉污染土壤提供参考。Bentonite is an excellent environmental material. In order to study the adsorption characteristics of bentonite for Cd(Ⅱ), hydrochloric acid, sodium hydroxide and sodium dodecyl sulfonate were used as modifiers to prepare modified bentonite. The effects of p H value, initial concentration and reaction time on the adsorption of Cd(Ⅱ) by modified bentonite were investigated by isothermal adsorption experiments, and the adsorption kinetics mechanism of Cd(Ⅱ) by modified bentonite was also discussed. XRD analysis showed that the layer spacing of modified bentonite increased and the diffraction peak intensity decreased. The removal rate of Cd(Ⅱ) by HCl-B increased with the increasing of pH value of the solution, and the removal rate of NaOH-B reached the maximum at pH=6, while B and SDS-B at pH=7. The removal rate of Cd(Ⅱ) by bentonite and modified bentonite decreased with the increasing of initial concentration, and the adsorption capacity of the adsorbent increased with increasing of the equilibrim concentration of Cd(Ⅱ). The equilibrium adsorption capacity of the bentonite and modified bentonite for different concentrations of Cd(Ⅱ) was corresponding with the Langmuir isotherm equation, and indicating that the adsorption of Cd(Ⅱ) on bentonite and modified bentonite was a monolayer adsorption process. The adsorption reaction of bentonite and modified bentonite basically reached equilibrium within 240 min. The pseudo-secondorder kinetic model can better describe the adsorption mechanism, and the chemisorption was main adsorption process, and the process of liquid film diffusion and intra-particle diffusion was rate-determining step for this adsorption prosess. This study can provide reference for the treatment of Cd-containing wastewater and remediation of Cd-contaminated soil by modified bentonite.

关 键 词：改性膨润土 Cd(Ⅱ) 吸附特征 吸附动力学 

分 类 号：X703[环境科学与工程—环境工程]