Study On The Electrokinetic Phenomena Of Charged Membranes

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.