平流式流动电位测试系统的研制

Fabrication of Tangential Streaming Potential Measurement System

分离膜表面的荷电化显著地影响着膜的分离性能和耐污染能力。因此,定量化表征膜表面电性能具有重要的理论价值和实际意义。作者在前期透过式膜流动电位测试系统研发工作的基础上成功地研制了平流式流动电位测试系统,并且首次将恒电流法测膜体电导引入膜表面ζ(Zeta)电位的确定过程中。以自制不同共混比的合金荷电膜为测试对象,利用该测试系统和经典的Helmholtz-Smoluchowski(H-S)方程及其变体得到了不同pH下的膜表面Zeta电位,从而揭示了膜表面电导、膜体电导对膜表面Zeta电位的贡献,并展示了该流动电位测试系统的有效性。

The characterization of the surface charge of polymeric membranes is of a great interest since surface electrical properties are known to greatly influence their filtration performance and fouling tendency. In this study, in order to obtain the direct information about the charged properties of the membrane skin-layer, a tangential streaming potential measurement system was successfully fabricated. In addition, it was noteworthy that a novel way that using constant current divect current to measure the system total conductance was incorporated into the measurement system. Then, the surface streaming potentials of the charged blend membranes which have different compositions under different pH were determined by means of the measurement system. After that, based on the steaming potential values, the membrane surface Zeta potentials were calculated by using the classical Helmholtz-Smoluchowski （H-S） formula and its versions which considering surface conductance and total conductance, respectively. The experimental results show the prominent influence of the contribution of surface conductance and body conductance on the Zeta potential values and the effectiveness of the self-made streaming potential measurement system.