Ion exchange membranes with preferential permselectivity for monovalent ions

We present a review of our studies on ion exchange membranes with preferential permselectivity for monovalent ions, which are mainly used to concentrate sea water for producing table salt. In this process, ion exchange membranes with preferential permselectivity are used of necessity to avoid any scale formation in the concentration chambers, owing to generation of salts with a low solubility: CaCO3, CaSO4 etc. Preferential permselectivity fo monovalent cations is achieved by covering the membrane surface with a very thin layer of a polycation. In the case of anion exchange membranes, we tried to modify the membranes in order to make the membrane structure more compact.