Preparation and Application of Ion Exchange Membranes for Selective Separation of Target Ions

Electro-membrane processes using ion-exchange membranes have been widely used in numerous applications, such as electrodialytic demineralization of saline water, treatment of industrial effluents. However, the presence of multivalent ions, such as CO32-, SO42- or Ca2+, Mg2+ may result in a detrimental risk of membrane scaling, which in turn hinder the membrane performance, for instance, decreasing the current efficiency and increasing the energy consumption. In order to improve these defects, ion-exchange membranes with specific selectivity for particular ions, like mono-valent membranes, may solve these problems. Although Astom claimed they had already produced high performance mono-valent selective membrane, there are few research focusing on this topic. Thus, the fundamental research is very important for ion-exchange membrane development. In addition, prevention of ion-exchange membrane fouling is one of the essential problems to overcome in their design and operation. Fouling causes deterioration in the membrane performance such as a decline in the ions flux and an increase in the electric resistance. In this case, development of mono-valent and antifouling ion exchange membranes with high-selectivity and low cost is meaningful and urgently required. Besides, remaining challenges include prolonging the life-span of the membrane, scale-up the use and keeping the stability is also needed to be solved. The PhD study aims at understanding the separation mechanism of the mono-valent and antifouling ion exchange membrane in aqueous solutions by responding to the challenges mentioned above. Preparation and characterization of mono-valent and antifouling ion exchange membranes will be studied at a pilot scale including different methods and materials to prepare mono-valent and antifouling membranes. Application of the membranes will be focused on the sea water concentration accompanying with the use of the mono-valent cation and anion ion exchange membranes. Antifouling property of ion exchange membranes will be studied concerning different kinds of solution including sea water, industrial effluents. Stability and membrane surface resistance of the newly developed membranes are the two main characteristics that needed to be considered during the operation.