Performance of some improved porous cellulose acetate membranes for low pressure reverse osmosis desalination

Abstract

The performance and correlations of experimental data with respect to a new and improved class of porous cellulose acetate membranes for low pressure reverse osmosis desalination are reported. These membranes were obtained from a casting solution of the following composition (weight %): acetone 68.0, cellulose acetate (acetyl content = 39.8% ) 17.0, water 13.5, and magnesium perchlorate 1.5; the temperature of the casting solution was 0°C, and the films were cast at the laboratory temperature (23–25°C) in an ambient atmosphere in equilibrium with 30 wt.% aqueous acetone solution; the solvent evaporation time on casting was 2 minutes, and the gelation medium was ice cold water. The productivity of the films made under the above conditions for brackish water desalination was 100 to 150% higher than that of other porous cellulose acetate membranes reported earlier at operating pressures of 250 psig or less. Some comparative data at higher operating pressures are also given.