The Dow Chemical Company

Filmtec Corporation

David J Forgach

Donald L Schmidt

Richard F Fibiger

Ritchie A Wessling

Michael J Colucci

Robert J Petersen

Ja-Young Koo

Thomas F Stocker

J Keith Harris

Melvin Rothberg

Gordon E Fleig

Jeffrey D Michalowski

Paul G Glugla

Roger B Hornby

Bill C Sager

A process is disclosed for the formation of a high flux composite membrane having a thin discriminating film affixed to a porous support layer through a glue layer. The process comprises the formation of the discriminating film by irradiating an aqueous polymer solution in the substantial absence of drying and under conditions which are sufficient to form a polymer film on the surface of the polymer solution at the interphase of the solution and a blanketing fluid. The film is then affixed to the support through the glue layer which may be the same polymer solution from which the discriminating film is formed.

Process of preparing a composite membrane

Hollow fiber structures for culturing mammalian cells in an agitated media are disclosed. These hollow fibers have a cylindrical wall surrounding a lumen preferably open at opposite ends of the fiber and have a length along the axis parallel to the lumen of not more than 5 centimeters. Hollow fiber structures which have their exterior surface coated to prevent cell attachment and growth thereon are also disclosed.

Growth of cells in hollow fibers in an agitated vessel

Reverse osmosis membranes treated with polymers bearing carboxylic acid groups and optionally pendant hydroxyl or amide moieties display enhanced salt rejection and/or increased water flux. This treatment is particularly useful for improving the membrane characteristics of cellulose acetate and polyamide membranes.

Rejection enhancing coatings for reverse osmosis membranes

An improved composite polyamide membrane and methods of making the membrane are described. This improved membrane is prepared using a cationic polymeric wetting agent in an aqueous solution containing a polyfunctional amine reactant which is interfacially polymerized with an acyl halide to form a thin film polyamide discriminating layer on a microporous support. Alternatively, the wetting agent can be applied directly to the substrate and the interfacial polymerization can occur on said treated substrate. The resulting membrane exhibits an unexpected combination of high water flux, high rejection of divalent anion salts, variable sodium chloride rejection and good caustic resistance at low operating pressures. In one embodiment of this invention, a porous substrate is first treated with an aqueous piperazine solution containing a copolymer of vinylbenzyl dimethyl sulfonium chloride and methacrylic acid and then the coated microporous support is contacted with trimesoyl chloride in an organic solvent.

Novel polyamide reverse osmosis membranes

Growing community of inventors

Midland, MI, United States of America

David J Forgach