Sulfonated polysulfone composite semipermeable membranes and process for their production

Abstract

Abstract Hydroquinone and dichlorophenysulfone are reacted to make a polysulfone having recurring units of formula (A): -O-(C 6 H 4 ) n -O-C 6 H 4 -para-SO 2 -C 6 H 4 - where n is an integer: this optionally is copolymerized with up to 10 mole% of units (B): (-O-C 6 H 4 -SO 2 -C 6 H 4 ) 2 , straight chain; the (co)polymer is dissolved in 97-98% sulphuric acid so as to substantially sulfonate the rings of units (A) but not of (B); the product has a molecular weight (shown by its viscosity in solution) sufficient to form a thin uniform film. The (co) polymer is dissolved in concn. of 0.05-10wt% in an alkylene glycol alkyl ether optionally admixed with up to 5 wt% of a non-protonic polar organic solvent (e.g. dimethyl sulfoxide) together with 0.01-80 wt% of a water-soluble and low volatile additive (e.g. a polyhydric alcohol or an inorganic salt), the solution is coated on a dry ultrafiltration menbrane as a support (e.g. a polymer, preferably a polysuffone) and the solvent is evaporated. Any remaining additive is washed out. Choice of additive affects the membrane performance. The product is a composite semipermeable membrane composed of the sulfonated (co) polysulfone of thickness 0.01-5um on the support and has a pure water flux higher than 3m 3 /m 2 day and good resistance to chlorine, acid and alkali; it is used for reverse osmosis and ultrafiltration.

Inventors

• 👤 Kenichi C/O Nitto Electric Ind. Co. Ltd. Ikeda
• 👤 Shouichi C/O Nitto Electric Ind. Co. Lt Yamamoto
• 👤 Hiroki C/O Nitto Electric Ind. Co. Ltd Ito

Bibliographic Details