Development of wet-dry reversible reverse osmosis membrane with high performance from cellulose acetate and cellulose triactate blend

Wet-dry reversible membrane were prepared bt a two-step coagulation procedure. A cast film containing a blend of cellulose triacetate as polymers, dioxane and acetone as solvents and maleic acid and methanol as additives was immersed consecutively in two aqueous coagulation baths, the first bath being kept at 0°C and the second at 60°C. The effects of casting solution composition and coagulation conditions on reverse osmosis performance and membrane morphology were examined. Light transmisssion measurements and demixing experiments have been carried out to investigate phase separation phenomena in this 6-component system. These experiments proved to be very helpfull in explaining the reverse osmosis results. High performance membrances have been obtained with salt rejections of more than 99% and permeation rates in the range of 10–121/ms2h. These desalination properties, combined with a good wet-dry reversibility, make our membranes superior to reverse osmosis membranes hitherto produced