Polyamide reverse osmosis membranes for desalination which have improved salt rejection and flux

摘要

Method of producing a polyamide reverse osmosis membrane by coating a support with a polyfunctional amide in a mixed solvent and reacting with organic solvent solution containing an amine-reactive reagent. The porous support is coated with a polyfunctional amine in one of three mixed solvents and contacted with an organic solution containing a polyfunctional acid halide, sulfonyl halide or isocyanate. The product is then dried to form the membrane. The three solvent mixtures are: (a) water and a polar compound being one of a di(propylene glycol) monoalkyl ether, an alkyl substituted 1,3-propanediol, di(ethylene glycol) hexyl ether; di(ethylene glycol) t-butyl methyl ether, tri(ethylene glycol) dimethyl ether or 1,2-, 1,3- or 1,4-cyclohexanedimethanol; (b) water and an alkoxyethanol; (c) water and two or more polar compounds: urea and an alkoxyethanol; di(ethylene glycol) hexyl ether and propylene glycol; di(ethylene glycol) hexyl ether and a sulfoxide derivative; di(ethylene glycol) hexyl ether and glycerol; an alkyl substituted 1,3-propanediol and a sulfoxide derivative; propylene glycol and a propylene glycol monoalkyl ether. Independent claims are included for membranes prepared by the method, both supported and unsupported.