Properties of new inorganic membranes prepared by metal alkoxide methods .2. New inorganic organic anion-exchange membranes prepared by the modified metal alkoxide methods with silane coupling agents

Abstract

Four types of inorganic-organic anion exchangeable membranes were prepared on a microporous alumina substrate by dip-coating with solution containing Si(OC2H5)(4), C2H5OH, H2O, CH3COOH, two silane coupling agents in molar ratio 1:6.8:2:0.03:0.02, and on a silica membrane by liquid-phase coupling method with two solutions containing C6H5CH3, H2O, 2-(trimethoxysilyl)ethyl-2-pyridine in molar ratio 11:0.06:0.04 or C2H5OH, H2O, N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride in molar ratio 21:0.06:0.06. The alumina substrate and silica membrane showed cation exchangeability, but membranes dip-coated and liquid-phase coupled showed anion exchangeability and their ion-exchange capacity per unit area of membrane surface were in the range 4-9 x 10(-3) meq. cm(-2). The static transport number for liquid-phase coupled membranes was in the range of 0.6-0.9, but for dip-coated membranes it was 0.5.