纳滤膜对不同阴阳离子的截留效果及分析

The Interception Effect of Nanofiltration Membrane on Different Cation and Anion

为考察纳滤膜对不同电解质离子的渗透截留效果,采用时代沃顿VNF1-4040型纳滤膜,对Cl^(-)、NO_(3)^(-)、SO_(4)^(2-)3种阴离子和Na^(+)、K^(+)、Mn^(2+)、Cu^(2+)、Zn^(2+)、Mg^(2+)6种阳离子组成的18种电解质的纳滤渗透过程展开了研究.结果表明:当阴离子为Cl^(-)和NO_(3)^(-)时,VNF1膜对阳离子的截留效果主要受电荷效应影响,二价阳离子的截留率高于一价阳离子;当阴离子为SO_(4)^(2-)时,静电排斥效应对阳离子的截留效果影响较大,受道南效应影响,一价阳离子的截留率大于二价阳离子;当阳离子相同时,SO_(4)^(2-)的截留率大于Cl^(-)和NO_(3)^(-),这是由于荷负电纳滤膜对阴离子的静电排斥效应与阴离子的负电荷数量相关;VNF1膜对2-1型电解质K_(2)SO_(4)、Na_(2)SO_(4)的截留率最高.

In order to investigate the interception effect of nanofiltration membrane on different electrolyte ions,the Vontron VNF1-4040 nanofiltration membrane was used to study the permeation process of 18 electrolytes composed of three anions(Cl^(-),NO_(3)^(-),SO_(4)^(2-))and six cations(Na^(+),K^(+),Mn^(2+),Cu^(2+),Zn^(2+),Mg^(2+)).The results show that as for Cl^(-)and NO_(3)^(-)electrolytes,the cation interception of VNF1 membrane is mainly affected by charge effect and the interception rate of divalent cation is higher than that of monovalent cation.As for SO_(4)^(2-)electrolytes,the electrostatic repulsion effect has a great influence on the interception effect of cation.Under the influence of Donnan effect,the interception rate of monovalent cation is higher than that of divalent cation.When the cation is the same,the interception rate of SO_(4)^(2-)is higher than that of Cl^(-)and NO_(3)^(-).This is because the electrostatic repulsive effect of negatively charged nanofiltration membrane on anions is related to the amount of negative charges carried by anions.VNF1 membrane has the highest interception rate for type 2-1 electrolytes K_(2)SO_(4)and Na_(2)SO_(4).