静电相互作用对荷电超滤过程中带电小分子清除的影响

Effects of electrostatic interactions on the clearance of small charged impurities through charged ultrafiltration membranes

研究了不同荷电量小分子(分子量为1kD左右)通过表面带同种电荷但荷电量不同的超滤膜(截留分子量为10kD)时的行为.实验结果表明,荷电超滤膜对带电小分子的截留作用与超滤膜荷电量、小分子带电量以及溶液离子强度密切相关.低离子强度条件下,荷电超滤膜对高荷电小分子的截留率很高,这主要是静电相互作用的结果.随着离子强度的增加,静电屏蔽作用增强,荷电超滤膜对带电小分子的截留作用也相应减小.结果还表明,表观透过率的实验值与基于滞膜模型的理论计算值有较好的吻合.

Ultrafiltration experiments were performed to evaluate the transmission of several model impurities （Mw-1 kD） with different electrical charges through ultrafiltration membranes （MWCO = 10 kD） having different surface charge characteristics. Results indicated that the retention of small charged impurities through charged ultrafiltration membranes are strongly dependent on the charge properties of membrane and molecules, and the solution ionic strength. Charged membranes have a high retention to charged small molecules with the same electricity in low ionic strength, which is mainly the result of electrostatic interactions. As the solution ionic strength increases, the effect of electrostatic shield increases and the sieving coefficient increases. Results also showed that the sieving data are in good agreement with the simple stagnant film model.