A NOVEL CHLORINE RESISTANT REVERSE OSMOSIS MEMBRANE

CURRENTLY AVAILABLE AND WIDELY USED AROMATIC POLYAMIDE (PA) REVERSE OSMOSIS (RO) MEMBRANES HAVE VERY LOW TOLERANCE TO STRONG OXIDANTS, ESPECIALLY CHLORINE. CONSEQUENTLY, THERE IS A NEED FOR RO MEMBRANES THAT ARE NOT SUSCEPTIBLE TO DEGRADATION BY CHLORINE ATTACK. USING A CHEMICALLY MODIFIEDPOLYMER, A CHLORINE-RESISTANT RO MEMBRANE CAN BE PRODUCED. THE CHEMICAL MODIFICATION INVOLVES THE ADDITION OF NITRO GROUPS TO AN AROMATIC PA. NITRO SUBSTITUTION OF ELECTRON-RICH AROMATIC RINGS PROTECTS THE RING AGAINST CHLORINE REACTION WHILE INCREASING THE HYDROPHILIC CHARACTER OF THE POLYMER. COMMERCIALLY AVAILABLE ARAMID POLYMERS WILL BE NITRATED AND CHARACTERIZED FOR DEGREE OF NITRATION, NITRATION GROUP FUNCTIONALITY, AND VISCOSITY. SUITABLE SOLVENTS WILL BE IDENTIFIED BOTH FOR POLYMER DISSOLUTION AND MEMBRANE CASTING. NITRATED PA MEMBRANES WILL BE TESTED FOR CHLORINE RESISTANCE AND FLUX/REJECTION CHARACTERISTICS. THE SKIN LAYER WILL BE EXAMINED FOR PORE SIZE AND PIN HOLES BY SCANNING ELECTRON MICROSCOPY. THIS PROGRAM WILL ESTABLISH THE TECHNICAL FEASIBILITY OF IMPROVING RO MEMBRANE CHLORINE RESISTANCE USING A NITRATED AROMATIC PA POLYMER. UF SUCCESSFUL, THE KNOWN CHARACTERISTIC OF NITRO GROUPS TO REDUCE THE REACTIVITY OF AROMATIC RINGS WITH CHLORINE WILL BE APPLIED TO COMMERCIAL PA MEMBRANES AS WELL AS TO AROMATIC POLYIMIDE MEMBRANES IN PHASE II.