A STUDY OF REVERSE-OSMOSIS SEPARATION AND PERMEATION RATE FOR SULFONATED POLY(2,6-DIMETHYL-1,4-PHENYLENE OXIDE) MEMBRANES IN DIFFERENT CATIONIC FORMS

Thin film composite membranes were prepared by coating a thin layer of sulfonated poly (1,4-dimethyl-2,6-phenylene oxide) polymer on the sur face of a polysulfone ultrafiltration membrane. The membrane performan ce was studied when the sulfonate was either in the hydrogen form or l oaded fully with an alkali metal cation. It was found that the permeat ion rate was greater than the pure water permeation rate, when the sul fonate was in the hydrogen form and the feed solution contained an alk ali metal chloride solute. The permeation rate increased with an incre ase in the ionic radius of the alkali metal cation. With respect to me mbranes in which the sulfonate was loaded with an alkali metal cation, the pure water permeation rate was found to increase with a decrease in the ionic radius of the alkali metal cation. The permeation rate wa s the same as the pure water permeation rate when the membranes of the latter form were tested for reverse osmosis of aqueous solutions invo lving either sodium chloride or an organic solute. (C) 1994 John Wiley & Sons, Inc.