Preparation of ultrathin reverse osmosis membranes and the attainment of theoretical salt rejection

Cellulose acetate reverse osmosis membranes, 600–2800 A. thick, have been prepared on glass surfaces by dipping a clean glass plate into a dilute solution of cellulose acetate. After drying, the membranes are floated of onto a water surface and placed on molecular filter supports. Theoretical salt rejections, as calculated from the solution‐diffusion model of membrane transport for cellulose acetate, were obtained with imperfection‐free membranes.