PREPARATION OF ANTIMONYL ACID CATION-EXCHANGE MEMBRANES BY USING SOL-GEL METHOD

A new inorganic cation-exchange membrane was successfully prepared on a microporous alumina substrate by dipcoating an antimonic acid sol solution obtained from a mixture of antimonic acid sol:Si(OC2H5)4:H2O:C2H5OH:HCl = 0.06:1:11:6.8:0.068 in molar ratio. The thickness, resistivity and ion-exchange capacity of the membrane increased with an increase in the number of dipcoated times, while the limiting current density showed a tendency to decrease. The ion-exchange capacity, area resistivity, limiting current density and transport number of Na+ for the 10 times coated membrane were 0.0061 meq.cm-2, 186.2 OMEGA.cm2, 0.96 A.dm-2 and 0.70, respectively. The membranes could stand in 6 M hydrochloric acid or nitric acid aqueous solution at 80-degrees-C for 24 h without any change in ion-exchange capacity.