DEVELOPMENT OF OXIDATION-RESISTANT MOSAIC MEMBRANES WITH ENHANCED TRANSPORT PROPERTIES

DESPITE SIGNIFICANT ADVANCES IN MEMBRANE SEPARATION TECHNOLOGY IN RECENT YEARS, ALL OF THE COMPONENTS OF MEMBRANE PROCESSES HAVE NOT BEEN OPTIMIZED TO PRODUCE MEMBRANES WITH HIGH TEMPERATURE STABILITY, OXIDATION RESISTANCE, IMPROVED ORGANIC REJECTIONS, AND THE ABILITY TO ATTAIN THE MINIMUM ENERGY REQUIREMENTS UNDER A GIVEN SET OF CONDITIONS. THIS PROGRAM IS DIRECTED TOWARD THE DEVELOPMENT OF A METHOD OF COMPOSITE MEMBRANE PREPARATION FROM ORGANIC POLYMERS THAT CAN BE TAILORED FOR A VARIETY OF SEPARATION PROCESSES, WHILE PRODUCING A MEMBRANE FLUX CONSIDERABLY HIGHER THAN PRESENTLY ATTAINABLE. UNLIKE TRADITIONAL METHODS OF COMPOSITE MEMBRANE PREPARATION, WHERE THE MEMBRANE BARRIER IS FORMED ON THE SURFACE OF A POROUS MEMBRANE SUPPORT, THE PROPOSED METHOD OF MEMBRANE PREPARATION INVOLVES THE FORMATION OF THE PERMSELECTIVE BARRIER WITHIN THE PORES OF THE MICROPOROUS SUPPORT. THIS IS ACCOMPLISHED BY A PROCESS OF OCCLUSION OR PORE-FILLING, WHEREBY THE REVERSE SIDE OF A FABRIC-REINFORCED MICROPOROUS MEMBRANE IS CONTACTED WITH A DILUTE SOLUTION OF A POLYMER WITH DESIRABLE TRANSPORT PROPERTIES. THE SOLUTION IS SUBSEQUENTLY DRAWN INTO THE FINE SURFACE PORES BY CAPILLARY ACTION AND THE POLYMER IS DEPOSITED WITHIN THE PORES AS THE SOLVENT EVAPORATES FROM THE MEMBRANE SURFACE. THUS, THE MEMBRANE BARRIER DOES NOT COVER THE ENTIRE SURFACE OF THE SUBSTRATE, YIELDING A MOSAIC SURFACE STRUCTURE WHICH ELIMINATES FLOW RESTRICTIONS RESULTING FROM THE BARRIER THICKNESS. IN ADDITION, BOTH THE TRANSPORT BARRIER POLYMER AND THE POROUS SUBSTRATE POLYMER CAN BE INDIVIDUALLY SELECTED FOR THEIR SPECIFIC FUNCTIONS.