阴离子在阴离子交换膜内扩散的分子动力学模拟  

Molecular dynamics simulation of anion diffusion in anion exchange membrane

作　　者：李丽[1] 金艳[1] 孙淑英[1] 于建国[1] LI Li;JIN Yan;SUN Shuying;YU Jianguo(National Engineering Research Center for Intergrated Utilization of Salt Lake Resources,East China University of Science and Technology, Shanghai 200000, China)

机构地区：[1]华东理工大学国家盐湖资源综合利用工程技术研究中心,上海200000

出　　处：《膜科学与技术》2019年第2期33-40,共8页Membrane Science and Technology

基　　金：上海市青年科技英才扬帆计划(17YF1403200)

摘　　要：电渗析技术已广泛应用于高盐废水浓缩处理中,结合分子动力学(MD)模拟与实验研究了阴离子在阴离子交换膜内的扩散过程.分子动力学模拟研究结果表明,阴离子在水溶液和膜中的扩散系数大小顺序有一定差异,分别为D(I^-)>D(Br^-)>D(Cl^-)>D(SO_4^(2-))和D(Cl^-)>D(Br^-)>D(I^-)>D(SO_4^(2-));通过径向分布函数分析得到r_(ion)^(2-)-N>r_(ion)^--N>r_(O-N),表明阴离子先与水缔和,再与季胺基团发生相互作用.其次,通过电化学交流阻抗(EIS)实验得到阴离子在膜中的自扩散系数大小顺序为D(Cl^-)>D(Br^-)>D(I^-)>D(SO_4^(2-)),与分子动力学模拟结果一致,离子在膜内扩散速率大小受离子水合半径和离子与膜的作用能共同影响,其中离子与膜的相互作用能起主导作用.Electrodialysis technology has been widely used in high-salt wastewater treatment.In this paper,molecular dynamics simulation(MD)and related experiment has been applied on the diffusion process of anions in anion exchange membrane.MD results show that the order of diffusion coefficients of anions in aqueous solution and membrane has a certain difference,which is D(I-)>D(Br-)>D(Cl-)>D(SO42-)and D(Cl-)>D(Br-)>D(I-)>D(SO42-),respectively.Radial distribution function result,rion2--N>rion--N>rO-N,indicates that anions associate with water priorly and then with quaternary amine groups.Then,the self-diffusion coefficient of the anion in the membrane is investigated by the electrochemical impedance spectroscopy(EIS)experiment,the results of which,D(Cl-)>D(Br-)>D(I-)>D(SO42-),is consistent with the molecular dynamics simulation.The diffusion rate of ions in the membrane is controlled by the ion hydration radius and the interaction energy between the ions and the membrane.The interaction between ions and membranes can play a leading role.

关 键 词：分子动力学 自扩散系数 电渗析 相互作用能 EIS 

分 类 号：O658.6[理学—分析化学]