Inorganic ion exchange membranes

A new class of ion exchange membranes has been developed for possible use in conversion of brackish water to fresh water. These membranes are based primarily on inorganic ion exchangers and have small quantities of extremely stable high temperature resistant organic polymers as binders.

The best cation exchange membranes to date utilize zirconium phosphate as the exchange material and Teflon or Kynar as the binder. The optimum anion exchange membranes have hydrous thorium oxide as the exchange material and the same organic binders.

The membranes are still in an early state of development but can be expected to show certain advantages over organic membranes. These include stability to high temperatures and to wetting-drying cycles. Resistance values and transference numbers of the membranes have not yet reached those of the organic ion exchange membranes but are in the process of improvement.