不同浓度Na^＋在紫色土颗粒表面电场作用下的吸附动力学研究  

The Adsorption Dynamics of Different Concentrations of Na^+ on Purple Soil Particles Under the Effect of Surface Electric Field

作　　者：杜伟[1] 李航[1] 李睿[1] 刘新敏[1] 

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,重庆400715

出　　处：《西南大学学报（自然科学版）》2015年第7期7-15,共9页Journal of Southwest University(Natural Science Edition)

基　　金：国家自然科学基金资助项目(41201223)

摘　　要：土壤颗粒表面大量的负电荷会在固-液界面产生强大的电场,影响土壤溶液中离子的吸附过程.本文以紫色土K+饱和样为研究对象,运用考虑表面电场的动力学新模型研究了不同浓度Na+离子的吸附动力学过程.实验结果表明:1当Na+离子浓度为9.565×10-5 mol/L时吸附过程中会出现明显的零级动力学特征和一级动力学特征.2浓度为7.826×10-4 mol/L和9.855×10-3 mol/L时Na+吸附过程中仅表现出一级动力学特征,这是因为增加Na+浓度后屏蔽电场的能力增强,从而表现出弱静电力吸附下的一级动力学过程.3实验中Na+的平衡吸附量随离子浓度的增加而递增,吸附速率随离子浓度递增而加速.4体系中K+亚稳吸附量随Na+离子浓度增加而递减,随表面电位递减而递减.通过对不同浓度下Na+吸附动力学特征分析,对了解离子交换吸附机理具有一定指导意义.The negative electric charge accumulated on soil particle surface will result in a strong electric field on the solid-liquid interface,which will influence the adsorption process of ions in the soil solution.In an experiment reported in this paper,a new model which takes into account the dynamics of the strong electric field was used to study the adsorption processes of Na^＋on K^＋-saturated purple soil.Zero-order and first-order kinetics characteristics appeared in the adsorption process under 9.565×10^-5 mol/L Na^＋.At relative higher Na^＋concentration（7.826×10^-4 mol/L and 9.855×10^-3 mol/L）,only first-order kinetics characteristics were observed,because the electric field at high Na＋concentration is weaker than at low ion concentration.The equilibrium absorption capacity and adsorption rate increased with increasing Na＋concentration.The metastable adsorption capacity of K＋in the system decreased with increasing Na＋concentration and with decreasing surface potential.The analysis of K^＋adsorption kinetics under different Na＋concentrations should be of certain significance to comprehending the mechanism of ion exchange adsorption.

关 键 词：固-液界面 吸附动力学 吸附速率 平衡吸附量 能量势垒 

分 类 号：S153[农业科学—土壤学]