静电位阻模型在纳滤膜跨膜电位解析中的应用

Application of the Electrostatic and Steric-hindrance Model to Analysis of Transmembrane Potential Across Nanofiltration Membranes

采用静电位阻模型对纳滤膜的跨膜电位进行了理论解析,考察了溶液体积通量密度、原料液浓度、阴阳离子扩散系数比、膜孔半径和膜体积电荷密度对KCl(1-1型电解质)和MgCl2(2-1型电解质)中的纳滤膜跨膜电位的影响.研究结果表明,随着通量密度的增大,KCl和MgCl2的跨膜电位线性程度增强;两种电解质的跨膜电位均随着原料液浓度和膜孔半径的增大而下降;在不同的考察范围内,阴阳离子扩散系数比对1-1型和2-1型电解质的跨膜电位的影响差别较大;KCl的跨膜电位随着膜体积电荷密度的变化关于零点呈现出对称性,而MgCl的跨膜电位零点则出现在膜体积电荷密度为负的条件下.

The electrostatic and steric-hindrance model was employed to analysis transmembrane potential arising across nanofiltration membranes theoretically.The effects of solution volume flux,feed concentration,diffusion coefficient ratio of co-ion to counterion,membrane pore radius and membrane volume charge density on transmembran potential including membrane potential and convective potential across nanofiltration membranes in KCl（1-1 electrolyte） and MgCl 2（2-1 electrolyte） were investigated.The results showed that the linearity of transmembrane potential of KCl and MgCl2 increased with increase of solution volume flux.Transmembrane potential of the two electrolytes decreased while feed concentration and pore radius increased.Due to the complex mechanism,the influence of diffusion coefficient ratio of co-ion to counterion on potentials behaved differently in different concentration range and electrolyte species.Compared with MgCl2,the curves of transmembrane potential of KCl as a function of membrane volume charge density exhibited evidently symmetry on the origin,but transmembrane potential zero point of MgCl 2 appeared when membrane volume charge density was negative.