来源：荷电膜的动电现象研究 发布时间：2010年7月22日
膜分离技术是一门新兴的分离技术，具有分离、浓缩和精制的功能，还有高效、节能、环保以及过程简单、易于自动控制等优点，目前已被广泛应用于水处理、电子、食品、化工等领域，产生了巨大的经济效益和社会效益。 膜是膜分离组件的核心部件之一。荷电膜因为其内外表面存在固定电荷，分离机理与中性膜有着较大的区别。因为膜上所带的固定电荷，荷电膜在抗污染、亲水性以及选择透过性等方面都存在明显优势，还可以用大孔径膜吸附分离较小粒径的微粒，而且可以分离粒径相似而荷电性能不同的组分。因此，表怔表面电荷性质对了解荷电膜的性能是非常必要的。通常，荷电膜的表面电荷都是用zeta电位来定量表征。但是，zeta电位不能直接测定，必须借助其它手段来间接计算而得。 荷电膜在外力如压力或电场力驱动下，可以观察到流动电位、电泳等动电现象。运用这种动电现象，可以推算出膜的zeta电位。而流动电位法由于实验方便、装置简易等优点成为最常用的实验手段之一。通过测定膜的流动电位，再用合适的方法就可以推算出相应的zeta电位。 本论文分别从理论和实验两个方面讨论了几种荷电膜的流动电位或压力驱动电位。正文部分总共包括六章，附录部分为相关的计算程序。 第一章是绪论。首先对荷电膜及其相关分离过程进行简介；然后重点介绍了荷电膜的动电现象，包括研究历史、相关概念、理论基础、流动电位实验手段及其应用；最后提出本论文的设计思想和工作内容。 第二章从实验方面探讨了均相离子交换膜的流动电位。分别讨论了外部溶液的种类、浓度和pH值以及膜自身的厚度和固定离子浓度对流动电位的影响；同时，通过观察相同压力下两个相反方向(即逐渐加压(+)与逐渐减压(-)方向)电位的差值，粗略估算出了离子交换膜在各个压力下的脱盐率。 第三章从理论方面探讨了多孔双极膜的流动电位。运用Navier-Stokes方程和Poisson-Boltzmann方程等，从理论上推导出双极膜的流动电位SPG，着重考察组成双极膜的阴、阳膜层的zeta电位、孔径、孔隙率和膜层厚度对SPG的影响。另外，运用实验室自制的双极膜及相应的阴、阳膜层，对理论模拟结果进行【Abstract】 Membrane separation is a novel technology, which has the function of separation, concentration and purification with the advantage of efficiency, energy-saving and environmental benigned. Moreover, membrane separation process is simple and of easy scalling-up. Therefore, this novel technology has been widely applied to many industrial fields such as water treatment, electronic engineering, food and chemical engineering, and it has brought about huge economic and social benefits.Membrane is the kernel component of the membrane separation modules. Because of the fixed charge on the surface, the separation mechanism of the charged membrane is different from that of the neutral one. Obvious predominance of separation using charged membranes lies in the anti-fouling, hydrophilicity and selectivity to ions compared with using neutral ones. Furthermore, small species can be separated using wide-pore membranes due to the electrostatic effect, and the components with similar sizes but different charge properties can be also separated. Therefore, it is necessary to characterize the surface charge for better understanding the performance of the charged membrane. Generally, the surface charge of the charged membrane is characterized by its zeta potential. However, the zeta potential can't be measured straightly, which can be only obtained by other indirect methods.The electrokinetic phenomena such as the streaming potential and electrophoresis can be observed if the charged membrane is induced by pressure gradients or electric forces. Fortunately, the zeta potential can be deduced from such electrokinetic measurement results. Recently, streaming potential has become one of the most frequently-used techniques on account of its experimental convenience. Then the zeta potential of the membrane can be easily worked out with some calculation methods from the streaming potential data.This dissertation is thus focused on the streaming potential or pressure-induced electrical potential of several charged membranes both theoretically and experimentally. There are six chapters in the body of the work, and the relevant calculation program in chapter is attached in the appendix part.