Selective membrane having a high fouling resistance

1. A composite polyamide reverse osmosis membrane comprising:

(a) a microporous support;

(b) a polyamide layer on said microporous support; and

(c) a hydrophilic coating on said polyamide layer, said hydrophilic coating being made by applying a hydrophilic compound to said polyamide layer, said hydrophilic compound including (i) at least one reactive group adapted to covalently bond directly to the polyamide membrane, said at least one reactive group being at least one of a primary amine and a secondary amine; and (ii) at least one hydrophilic group, said at least one hydrophilic group being selected from the group consisting of a hydroxyl group, a carbonyl group, a trialkoxysilane group, an anionic group, and a tertiary amino group; (iii) wherein said hydrophilic compound is devoid of a polyalkylene oxide group and wherein said hydrophilic compound is selected from the group consisting of 1,3-diamino-2-propanol, ethanolamine, diethanolamine, 3-amino-1-propanol, 4-amino-1-butanol, and 2-amino-1-butanol.

2. A composite polyamide reverse osmosis membrane comprising:

(a) a microporous support;

(b) a polyamide layer on said microporous support; and

(c) a hydrophilic coating on said polyamide layer, said hydrophilic coating being made by applying a hydrophilic compound to said polyamide layer, said hydrophilic compound including (i) at least one reactive group adapted to covalently bond directly to the polyamide membrane, said at least one reactive group being at least one of a primary amine and a secondary amine; and (ii) at least one hydrophilic group, said at least one hydrophilic group being selected from the group consisting of a hydroxyl group, a carbonyl group, a trialkoxysilane group, an anionic group, and a tertiary amino group; (iii) wherein said hydrophilic compound is devoid of a polyalkylene oxide group and wherein said hydrophilic compound has a linear structure represented by the formula:

RNH—CH 2 —CH(OH)—(CH 2 O) A —(CH 2 ) X —[CH(OH)] B —(CH 2 ) Y —(O—CH 2 ) C —CH(OH)—CH 2 —(NHR) D

wherein R is hydrogen or an alkyl or alkenyl group having from 1 to 6 carbon atoms; wherein each of X and Y is an integer ranging from 0 to 6, independently of one another; wherein (CH 2 ) X and (CH 2 ) Y is alkyl or alkenyl and is linear, branched or cyclic; wherein each of A, C and D is 0 or 1, independently of one another; and wherein B is an integer ranging from 0 to 100.

3. The composite polyamide reverse osmosis membrane as claimed in claim 2 wherein said hydrophilic compound is selected from the group consisting of 4,8-dioxa-2,6,10-trihydroxy-1,11-monodecanediamine, 4,7-dioxa-2,9-dihydroxy-1,10-decanediamine, 2,3-dihydroxy-1,4-butanediamine, 3-anino-1,2-propanediol, glucamine, N-methylglucamine, and tris(hydroxymethyl)aminomethane.

4. A composite polyamide reverse osmosis membrane comprising:

(a) a microporous support;

(b) a polyamide layer on said microporous support; and

(c) a hydrophilic coating on said polyamide layer, said hydrophilic coating being made by applying a hydrophilic compound to said polyamide layer, said hydrophilic compound including (i) at least one reactive group adapted to covalently bond directly to the polyamide membrane, said at least one reactive group being at least one of a primary amine and a secondary amine; and (ii) at least one hydrophilic group, said at least one hydrophilic group being selected from the group consisting of a hydroxyl group, a carbonyl group, a trialkoxysilane group, an anionic group, and a tertiary amino group; (iii) wherein said hydrophilic compound is devoid of a polyalkylene oxide group and wherein said hydrophilic compound has a branched structure and is made by the reaction of ammonia or its derivatives with an epoxy compound having three or more epoxy groups.

5. The composite polyamide reverse osmosis membrane as claimed in claim 4 wherein said hydrophilic compound is selected from the group consisting of the reaction products of ammonia or its derivatives and glycerol triglycidyl ether, the reaction products of ammonia or its derivatives and 1,1,1-tris(hydroxymethyl)ethane triglycidyl ether, and the reaction products of ammonia or its derivatives and sorbitol tetraglycidyl ether.

6. A composite polyamide reverse osmosis membrane comprising:

(a) a microporous support;

(b) a polyamide layer on said microporous support; and

(c) a hydrophilic coating on said polyamide layer, said hydrophilic coating being made by applying a hydrophilic compound to said polyamide layer, said hydrophilic compound including (i) at least one reactive group adapted to covalently bond directly to the polyamide membrane, said at least one reactive group being at least one of a primary amine and a secondary amine; and (ii) at least one hydrophilic group, said at least one hydrophilic group being selected from the group consisting of a hydroxyl group, a carbonyl group, a trialkoxysilane group, an anionic group, and a tertiary amino group; (iii) wherein said hydrophilic compound is devoid of a polyalkylene oxide group and wherein said hydrophilic compound is selected from the group consisting of the reaction products of ammonia or its derivatives and hydroquinone diglycidyl ether, the reaction products of ammonia or its derivatives and resorcinol diglycidyl ether, and the reaction products of ammonia or its derivatives and bisphenol A diglycidyl ether.

7. A composite polyamide reverse osmosis membrane comprising:

(a) a microporous support;

(b) a polyamide layer on said microporous support; and

(c) a hydrophilic coating on said polyamide layer, said hydrophilic coating being made by applying a hydrophilic compound to said polyamide layer, said hydrophilic compound including (i) at least one reactive group adapted to covalently bond directly to the polyamide membrane, said at least one reactive group being at least one of a primary amine and a secondary amine; and (ii) at least one hydrophilic group, said at least one hydrophilic group being selected from the group consisting of a hydroxyl group, a carbonyl group, a trialkoxysilane group, an anionic group, and a tertiary amino group, wherein said at least one hydrophilic group comprises at least one carbonyl group; (iii) wherein said hydrophilic compound is devoid of a polyalkylene oxide group.

8. The composite polyamide reverse osmosis membrane as claimed in claim 7 wherein said hydrophilic compound is selected from the group consisting of aminoacetaldehyde dimethyl acetal, α-aminobutyrolactone, 3-aminobenzamide, 4-aminobenzamide and N-(3-aminopropyl)-2-pyrrolidinone.

9. A composite polyamide reverse osmosis membrane comprising:

(a) a microporous support;

(b) a polyamide layer on said microporous support; and

(c) a hydrophilic coating on said polyamide layer, said hydrophilic coating being made by applying hydrophilic compound to said polyamide layer, said hydrophilic compound including (i) at least one reactive group adapted to covalently bond directly to the polyamide membrane, said at least one reactive group being at least one of a primary amine and a secondary amine; and (ii) at least one hydrophilic group, said at least one hydrophilic group being selected from the group consisting of a hydroxyl group, a carbonyl group, a trialkoxysilane group, an anionic group, and a tertiary amino group, wherein said at least one hydrophilic group comprises at least one trialkoxysilane group; (iii) wherein said hydrophilic compound is devoid of a polyalkylene oxide group.

10. The composite polyamide reverse osmosis membrane as claimed in claim 9 wherein said hydrophilic compound is selected from the group consisting of (3-aminopropyl)triethoxysilane and (3-aminopropyl)trimethoxysilane.

11. A composite polyamide reverse osmosis membrane comprising:

(a) a microporous support;

(b) a polyamide layer on said microporous support; and

(c) a hydrophilic coating on said polyamide layer, said hydrophilic coating being made by applying a hydrophilic compound to said polyamide layer, said hydrophilic compound including (i) at least one reactive group adapted to covalently bond directly to the polyamide membrane, said at least one reactive group being at least one of a primary amine and a secondary amine; and (ii) at least one hydrophilic group, said at least one hydrophilic group being selected from the group consisting of a hydroxyl group, a carbonyl group, a trialkoxysilane group, an anionic group, and a tertiary amino group, wherein said at least one hydrophilic group comprises at least one anionic group; (iii) wherein said hydrophilic compound is devoid of a polyalkylene oxide group.

12. The composite polyamide reverse osmosis membrane as claimed in claim 11 wherein said hydrophilic compound is selected from the group consisting of glycine, taurine, 3-amino-1-propanesulfonic acid, 4-amino-1-butanesulfonic acid, 2-aminoethyl hydrogen sulfate, 3-aminobenzenesulfonic acid, 3-amino-4-hydroxybenzenesulfonic acid, 4-aminobenzenesulfonic acid, 3-aminopropylphosphonic acid, 3-amino-4-hydroxybenzoic acid, 4-amino-3-hydroxybenzoic acid, 6-aminohexanoic acid, 3-aminobutanoic acid, 4-amino-2-hydroxybutyric acid, 4-aminobutyric acid and glutamic acid.

13. A composite polyamide reverse osmosis membrane comprising:

(a) a microporous support;

(b) a polyamide layer on said microporous support; and

(c) a hydrophilic coating on said polyamide layer, said hydrophilic coating being made by applying a hydrophilic compound to said polyamide layer, said hydrophilic compound including (i) at least one reactive group adapted to covalently bond directly to the polyamide membrane, said at least one reactive group being at least one of a primary amine and a secondary amine; and (ii) at least one hydrophilic group, said at least one hydrophilic group being selected from the group consisting of a hydroxyl group, a carbonyl group, a trialkoxysilane group, an anionic group, and a tertiary amino group, wherein said at least one hydrophilic group comprises at least one tertiary amino group; (iii) wherein said hydrophilic compound is devoid of a polyalkylene oxide group.

14. The composite polyamide reverse osmosis membrane as claimed in claim 13 wherein said hydrophilic compound is selected from the group consisting of 3-(dimethylamino)propylamine, 3-(diethylamino)propylamine, 4-(2-aminoethyl)morpholine, 1-(2-aminoethyl)piperazine, 3,3′-diamino-N-methyldipropylamine and 1-(3-aminopropyl)imidazole.