The effect of the substrate membrane on the performance of sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) - polyetherimide thin film composite membranes for low-pressure reverse osmosis.

Abstract

Thin film composite (TFC) membranes were prepared by coating sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) of ion-exchange capacity value of 1.8 meq/g on top of substrate polyetherimide (PEI) membranes with various mean pore sizes which were also laboratory prepared. Both substrate membranes and TFC membranes were characterized by the mean pore size and pore size distribution, which were determined by analyzing the reverse osmosis separation data for aqueous solutions of polyethylene glycols of different molecular weights. Low pressure reverse osmosis performance of the composite membranes was also investigated by using aqueous electrolyte solutions. A parameter, N/delta, representing the pore density divided by the total thickness of both the thin coated film of the TFC membrane and the skin of the porous substrate membrane, was calculated for both the substrate and the thin film composite membranes. Scanning electron microscopy was utilized to investigate the morphological structure of the substrate membranes. (Abstract shortened by UMI.)