PREPARATION AND CHARACTERIZATION OF HIGH-PERFORMANCE DEHYDRATING PERVAPORATION ALGINATE MEMBRANES

In a previous work, sodium alginate dense membranes demonstrated a goo d combination of selectivity and permeation flux for dehydrating organ ic solvents by pervaporation. In this article, the pervaporation perfo rmances of alginate composite membranes has been investigated to find out the best condition of membrane formation and the optimum operating conditions. Some ultrafiltration membranes made of poly(vinylidene fl uoride), polyacrylonitrile, and hydrolyzed polyacrylonitrile-either co mmercially available or prepared in our laboratories--were used as sup ports for the composite membranes. Sodium alginate dense membranes, mo dified through ion ex change of sodium with multivalent metal ions (su ch as Al3+, Cr3+, Fe3+, and Mg2+) have also been prepared, and their p ermselectivities have been tested for the water-ethanol mixture. An in teresting stability of the modified membranes in long-term operation i s expected. (C) 1998 John Wiley & Sons, Inc.