Inventors:
Charles R. Mungle - San Diego CA
Ronald L. Fox - San Diego CA
Assignee:
The United States of America as represented by the Secretary of the
Interior - Washington DC
International Classification:
B29D 2704
B29D 2720
B01D 3900
Abstract:
Asymmetric cellulose triacetate semipermeable membranes cast from a solution of cellulose triacetate having an acetyl content of at least 43 percent in a solvent mixture having a ratio of dioxane to acetone of at least about 1. 5 to 1, which solution also contains a swelling agent in the form of a low molecular weight alcohol or a low molecular weight mono- or poly-basic acid. Solvent is evaporated from one surface of the cast film to form a dense gel layer and the film is immersed in water to provide an asymmetric semipermeable membrane having a high salt-rejection capability and good flux.