蒙脱石/紫色土表面电化学性质对离子吸附行为的影响  

Influence of Electrochemical Properties of Montmorillonite/Purple Soil Surface on Ion Adsorption Behavior

作　　者：马倩 陈梓歆 李睿[1] MA Qian;CHEN Zixin;LI Rui(Chongqing Key Laboratory of Multiscale Interfacial Processes and Regulation of Soils/College of Resources and Environment,Southwest University,Chongqing 400715,China)

机构地区：[1]土壤多尺度界面过程与调控重庆市重点实验室/西南大学资源环境学院,400715

出　　处：《西南大学学报（自然科学版）》2024年第12期169-179,共11页Journal of Southwest University(Natural Science Edition)

基　　金：国家重点研发计划项目(2023YFD1900300)。

摘　　要：表面电化学性质对于土壤溶液中离子的扩散迁移起重要作用,通过Mg^(2+),Cd^(2+),Pb^(2+)3种离子在蒙脱石/紫色土颗粒表面的吸附动力学实验,讨论离子在蒙脱石/紫色土表面的吸附与电化学行为之间的关系.结果表明:在低电解质浓度条件下(5×10^(-5),1×10^(-4)mol/L),Mg^(2+),Cd^(2+),Pb^(2+)在紫色土颗粒表面的平衡吸附量与紫色土CEC的比值,均大于3种离子在蒙脱石颗粒表面的平衡吸附量与蒙脱石CEC的比值(即亚稳吸附程度).在此基础上,分析不同电解质条件下两种不同表面的电化学性质.得出以下结论:在相同电解质浓度条件下,Mg^(2+),Cd^(2+),Pb^(2+)在紫色土颗粒表面电位φ0的绝对值、电荷密度σd和电场强度Ed均大于在蒙脱石颗粒表面电位φ0的绝对值、电荷密度σd和电场强度Ed;在相同电解质类型条件下,Mg^(2+),Cd^(2+),Pb^(2+)达到吸附平衡时,阳离子距离土壤/矿物表面d处的电荷密度σd和电场强度Ed均随着电解质溶液浓度的升高而增大.表明吸附材料表面电化学性质的不同会对阳离子的吸附行为起决定性作用.Surface electrochemical properties play an important role in the diffusion and migration of ions in soil solution.In this study,the adsorption kinetics experiments of Mg^(2+),Cd^(2+)and Pb^(2+)on the surface of montmorillonite/purple soil particles were conducted to discuss the relationship between the adsorption and electrochemical behavior of ions on the surface of Montmorillonite/purple soil particles.The experimental results show that:under the condition of low electrolyte concentration(5×10^(-5),1×10^(-4)mol/L),the equilibrium adsorption capacity of Mg^(2+),Cd^(2+)and Pb^(2+)on the surface of purple soil particles and the ratio of CEC of purple soil are all greater than the equilibrium adsorption capacity of the three ions on the surface of montmorillonite particles and the ratio of montmorillonite CEC(i.e.,metastable adsorption degree).On this basis,the electrochemical properties of two different surfaces under different electrolyte conditions were analyzed.The following conclusions are drawn:under the same electrolyte concentration,the absolute value of surface potentialφ0,charge densityσd and electric field intensity E d of Mg^(2+),Cd^(2+)and Pb^(2+)in purple soil particles are greater than the absolute value of surface potentialφ0,charge densityσd and electric field intensity E d of montmorillonite particles.Under the same electrolyte type,when Mg^(2+),Cd^(2+)and Pb^(2+)reached adsorption equilibrium,the charge densityσd and the electric field intensity E d at the cation distance d from the soil/mineral surface increased with the increase of electrolyte solution concentration.It is shown that the difference in the surface electrochemical properties of adsorbed materials indeed plays a decisive role in the adsorption behavior of cations.

关 键 词：恒电荷 蒙脱石 紫色土 表面电化学性质 离子吸附 

分 类 号：X53[环境科学与工程—环境工程] S153[农业科学—土壤学]