THE MECHANISM OF HALOGEN ATTACK ON COMPOSITE REVERSE-OSMOSISMEMBRANES

MANY REVERSE-OSMOSIS MEMBRANES COMMERCIALLY AVAILABLE TODAY ARE MADE FROM POLYAMIDE OR POLYUREA MEMBRANES. THESE MEMBRANES GIVE HIGH SALT REJECTION AND HIGH WATER FLUX- YET ARE RAPIDLY DEGRADED WHEN EXPOSED TO TRACE LEVELS OF CHLORINE OR OTHER HALOGEN DISINFECTANTS USED FOR THE PRETREATMENT OF FEED WATERS. EFFORTS TO DEVELOP CHLORINE-RESISTANT MEMBRANES HAVE BEEN SLOW BECAUSE OF THE INCOMPLETE UNDERSTANDING OF THE INTERACTIONS BETWEEN CHLORINE AND THE MEMBRANES. BASED ON PREVIOUS WORK, WE HAVEFORMULATED A MODEL THAT DESCRIBES THE MECHANISMS OF HALOGEN ATTACK ON NITROGEN-CONTAINING MEMBRANES. THE OBJECTIVES OF THIS PROPOSED PROGRAM ARE TWO-FOLD: 1) TO VERIFY THE PROPOSED MECHANISMS BY STUDYING THE REACTIONS OF CHLORINE AND OTHER HALOGENS WITH SPECIFIC FUNCTIONAL GROUPS PRESENT IN POLYAMIDE AND POLYUREA MEMBRANES, AND 2) TO USE THIS INFORMATION TO DEVELOP HIGH-PERFORMANCE CHLORINE-RESISTANT MEMBRANES.