High flux RO/UF membranes

Claim 2

A dynamically formed, bifurcated membrane for reverse osmosis or ultrafiltration comprising a thin, hydrophilic, crosslinked, polymeric film deposited on under pressure and chemically bonded to a porous, polymeric support, wherein the thin, hydrophilic film is crosslinked by polyfunctional low molecular weight compounds, and the porous polymeric support is optionally crosslinked.

Claim 3

A membrane as in claim 1 obtained by (a) coating a chemically-reactive polymer from a dilute aqueous solution under pressure to form a thin film on a porous polymeric support having functional moieties reactive with the polymeric thin film, and (b) crosslinking the thin polymeric film deposited on and chemically bound to the porous polymeric support with polyfunctional low molecular weight compounds.

Claim 4

A membrane as in claim 2, wherein the porous polymeric support having functional moieties comprises a polymer selected from the group consisting of cellulose, cellulose derivatives, polyvinyl alcohols, polyacrylonitriles, polyepoxides, polystyrenes, and polysulfones into which reactive functional moieties have been introduced by chemical modification.

Claim 5

A membrane as in claim 2, wherein crosslinking step (b) has been carried out with polyfunctional, ionic, low molecular weight compounds.

Claim 6

A membrane as in claim 1, wherein the thin, polymeric, deposited film has a thickness less than 5000 A, preferably less than 1000 A.

Claim 7

A process for separating chemical species comprising the step of filtering aqueous solutions of mixtures of species through the membrane of claim 1.

Claim 8

A process for reverse osmosis or ultrafiltration of aqueous liquids comprising the steps of: (a) disposing on one side of a membrane as in claim 1 a solution bearing a solute, and (b) filtering that solution through said membrane by applying a hydraulic pressure to the solution and the membrane greater than the osmotic pressure of the solution.

Claim 9

A membrane according to claim 1, wherein the thin film is a monomolecular layer.

Claim 10

A process for making a dynamically formed bifurcated membrane for reverse osmosis or ultrafiltration comprising a thin, hydrophilic, crosslinked, polymeric film deposited on under pressure and chemically bonded to a porous, polymeric support by steps comprising: (a) coating a chemically-reactive polymer from a dilute aqueous solution under pressure to form a thin film on a porous polymeric support having functional moieties reactive with the polymeric thin film, and (b) crosslinking th thin polymeric film deposited on and chemically bound to the porous polymeric support with polyfunctional low molecular weight compounds.

Claim 11

A process for making a dynamically formed bifurcated membrane for reverse osmosis or ultrafiltration comprising a thin, hydrophilic, crosslinked, polymeric film deposited on under pressure and chemically bonded to a porous, polymeric support by steps comprising: (a) coating a chemically-reactive polymer from a dilute aqueous solution under pressure to form a thin film on a porous polymeric support having functional moieties reactive with the polymeric thin film, and (b) crosslinking th thin polymeric film deposited on and chemically bound to the porous polymeric support with polyfunctional low molecular weight compounds.

Claim 12

A process as in claim 9, wherein the chemically-reactive polymer of step (a) and the polyfunctional low molecular weight compounds of step (b) are codeposited from the dilute aqueous solution under pressure onto the porous polymeric support.

Claim 13

A process as in claim 10, followed by crosslinking the reactive polymer bonds with the polyfunctional low molecular weight compounds.

Claim 14

A process as in claim 10, wherein the polyfunctional, low molecular weight compound is colorless, nonionic and selected from the group consisting of cyclic carbonic acid imide halides, dihalides of dicarboxylic acids, dialdehydes, and trihalides of tricarboxylic acids.

Claim 15

A process as in claim 9, wherein crosslinking step (b) is carried out with ionic, polyfunctional, low molecular weight compounds.

Claim 16

A process as in claim 13, wherein the polyfunctional low molecular weight compounds of step (b) are nonionic compounds containing at least two substituents reactive with the polymeric thin film and the functional moieties of the porous support.

Claim 17

A process as in claim 14, wherein the polyfunctional, nonionic, low molecular weight compound is colorless and selected from the group consisting of carbonic acid imide halides, dihalides of dicarboxylic acids, dialdehydes, and trihalides of tricarboxylic acids.

Claim 18

A process as in claim 9, wherein the porous support having functional moieties of step (a) is selected from the group consisting of cellulosics, cellulose derivatives, bisphenol epoxy adducts, polymers derived from polyvinyl alcohol by reaction with organic compounds containing at least two functional moieties, polyacrylonitriles modified by reaction with hydroxylamine, polyacrylonitriles modified by reaction with hydroxylamine and an organic compound containing at least two functional moieties, polysulfones containing reactive moieties preferably aromatically substituted, and polystyrenes containing reactive moieties preferably aromatically substituted.

Claim 19

A process as in claim 16, wherein the reactive moieties attached to the aromatic polysulfones or polystyrenes have been introduced by a step selected from the group consisting of haloalkylation, chloromethylation, and coupling with diazocompounds, followed by further chemical modification after said step.

Claim 20

A process as in claim 16, wherein the compounds containing at least two functional moieties are selected from the group consisting of: (1) compounds containing reactive multiple bonds, epoxide, aziridine, aldehyde, imidate, isocyanate, hydroxyl, and anhydride moieties; (2) compounds containing substituents detachable as tertiary amines, compounds containing substituents detachable as anions, preferably halogen anions, and (3) compounds containing a combination of the moieties of (1) and (2) herein.

Claim 21

A process as in claim 18, wherein the compounds are selected from the group consisting of cyclic carbonic acid imide halides, isocyanates, isothiocyanates, and N-methylol compounds.

Claim 22

A process as in claim 19, wherein the compounds containing at least two functional moieties are selected from the group consisting of halogenodiazines, halogenotriazines, halogenodiazines with ionic groups, and halogenotriazines with ionic groups.

Claim 23

A process as in claim 16, wherein the polyfunctional low molecular weight compounds of step (b) are ionic compounds containing at least two substituents reactive with the polymeric thin film and the functional moieties of the porous support.

Claim 24

A process as in claim 21, wherein the polyfunctional ionic compound is a reactive azo dye bearing a substituent selected from the group consisting of sulfonic acid, carboxyl moiety, and ammonium moiety.

Claim 25

A process as in claim 22, wherein the polyfunctional ionic compound is a reactive azo dye containing at least one of sulfonic acid and carboxylic acid and a reactive moiety selected from the group consisting of monochlorotriazinyl, dichlorotriazinyl, 2,4-dichloropyrimidinyl, vinyl sulfonyl, beta-sulfatoethylsulfonyl, beta-chloroethylsulfonyl, and beta-sulfatoethylamino sulfonyl.

Claim 26

A process as in claim 21, wherein the polyfunctional, ionic, low molecular weight compound is colorless and is at least one of halotriazinyl and halopyrimidyl compounds.

Claim 27

A process as in claim 9, wherein the chemically-reactive polymer is at least one of aliphatic and aromatic polymer containing a moiety selected from the group consisting of amino, hydroxyl, thiol, and epoxy.

Claim 28

A process as in claim 25, wherein said polymer is selected from the group consisting of polyethyleneimines, polyvinyl alcohols, cellulose derivatives, polyvinylamines, polyvinyl anilines, polypiperidines, polydiallyamines, amino-modified polyepihalohydrins, condensation products of dicyandiamide, methylolated ammonium salts, diamino condensation products of polyanhydrides, aminoalkylated polysulfones, aminoalkylated polyphenylene oxides, and polyamido-polyamino epichlorohydrin resins.

Claim 29

A process as in claim 9, wherein the dilute aqueous solution of step (a) contains from about 0.01 to about 5 percent by weight of the chemically-reactive polymer.

Claim 30

A process as in claim 27, wherein the dilute aqueous solution of step (a) contains from about 0.01 to about 1 percent by weight of the chemically-reactive polymer.

Claim 31

A process as in claim 9, wherein the pressure employed in step (a) is from about 100 bar.

Claim 32

A dynamically formed membrane for reverse osmosis or ultrafiltration obtained by (a) depositing a chemically-reactive polymer from a dilute aqueous solution under pressure to form a thin film on a porous polymeric support having functional groups reactive with the polymeric thin film, and (b) crosslinking the thin polymeric film deposited on and chemically bonded to the porous polymeric support with polyfunctional low molecular weight compounds; wherein (c) the polymeric porous support of (a) is selected from the group consisting of cellulose, cellulose derivatives; bis-phenol-epoxy adducts; polyvinyl alcohol, chemically modified through reaction with an organic compound containing at least two functional groups; polymers of acrylonitrile, chemically modified by reaction with hydroxylamine or hydroxylamine and an organic compound containing at least two functional groups; aromatic polysulfones, and polystyrenes containing reactive groups; and (d) the polyfunctional, low molecular weight compounds of (b) are at least one of a group consisting of organic compounds containing reactive multiple bonds, epoxide, aziridine, aldehyde, imidate, isocyanate, hydroxyl, and anhydride groups, compounds containing substituents detachable as tertiary amines or as anions, halogen anions, and compounds containing any combination of these moieties.

Claim 33

A dynamically formed membrane for reverse osmosis or ultrafiltration obtained by (a) depositing a chemically-reactive polymer from a dilute aqueous solution under pressure to form a thin film on a porous polymeric support having functional groups reactive with the polymeric thin film, and (b) crosslinking the thin polymeric film deposited on and chemically bonded to the porous polymeric support with polyfunctional low molecular weight compounds; wherein (c) the polymeric porous support of (a) is selected from the group consisting of cellulose, cellulose derivatives; bis-phenol-epoxy adducts; polyvinyl alcohol, chemically modified through reaction with an organic compound containing at least two functional groups; polymers of acrylonitrile, chemically modified by reaction with hydroxylamine or hydroxylamine and an organic compound containing at least two functional groups; aromatic polysulfones, and polystyrenes containing reactive groups; and (d) the polyfunctional, low molecular weight compounds of (b) are at least one of a group consisting of organic compounds containing reactive multiple bonds, epoxide, aziridine, aldehyde, imidate, isocyanate, hydroxyl, and anhydride groups, compounds containing substituents detachable as tertiary amines or as anions, halogen anions, and compounds containing any combination of these moieties.

Claim 34

The dynamically formed membrane of claim 30, wherein the polystyrene of (c) has the reactive groups attached to the aromatic moieties of these polymers.

Claim 35

The dynamically formed membrane of claim 30, wherein the anion of (d) is a halogen anion.