不对称膜在电解质溶液中产生的电势及其迭加作用

OCCURRENCE AND ACCUMULATIVE EFFECT OF ASYMMETRIC MEMBRANE POTENTIAL IN THE ELECTROLYTE SOLUTIONS

二醋酸纤维素不对称膜是非荷电膜。当这种膜分隔两相同组份和浓度的电解质溶液时在膜的两侧产生电势,称为不对称膜电势。该电势产生原因是膜内外化学势差,引起离子向膜内扩散,由于离子在膜的两界面有不同的迁移速度,因而在两界面出现电势差。该电势随时间出现最大值,然后逐渐降为零。电势变化特性与电解质溶液的性质有关。当把数张不对称膜以其致密层向同一方串联排列,两邻膜用电解质溶液连接,构成一体系。该体系的不对称膜有膜电势的迭加作用。

Asymmetric cellulose acetate membrane is a noncharged membrane.When use this membrane to separate two identical solutions of oneelectrolyte.Potential is created between the two sides of the membrane.This potential is defined as the asymmetric membrane.The reason why the potential is produced is regarded as ion diffu-sion into membrane.The diffusion is caused by the difference of thechemical potentials of inside and outside the membrane.Since the iondiffusion velocities to the two sides of the membrane are different,thepotential is produced.It is reasonable that there is a maximumpotential on the potential-time curve and there is a zero potential inthe end of the curve.It is found that the speciality of each potential-time curve isrelied on the property of each electrolyte.It is also found that theasymmetric potential has the accumulative effect when arrangeseveral membranes in the direction of the dense layer to separateidentical solutions of an electrolyte.