Performance of hydroxy sodalite membranes as absolute water selective materials under acidic and basic conditions

Gas tight α-alumina supported hydroxy sodalite membranes were employed in pervaporation, testing the acid and base stability of the membranes through prolonged dehydration of acetic acid/water mixtures and sodium hydroxide solutions with different concentrations at 473 K and 2.2 MPa cross-membrane pressure. Under continuous operation for approximately 320 h, hydroxy sodalite membranes showed good acid and base stability within a feed pH range of 2.9–13.7. Under these conditions the membrane showed absolute selectivity towards water, and the flux through the membrane remained fairly stable. The membranes were also employed in dehydration of acetone/water mixtures at different temperatures and feed compositions. The membrane exhibited a water/acetone separation factor larger than 106.