NL1020950C2 - Composite polyamide reverse osmosis membrane for desalination of seawater, comprises polyamide layer and hydrophilic coating of polyfunctional epoxy compound, formed sequentially on microporous support - Google Patents

Abstract

The composite polyamide reverse osmosis membrane comprises a polyamide layer and a hydrophilic coating provided sequentially on a microporous support. The hydrophilic coating is formed by applying a polyfunctional epoxy compound having at least two epoxy groups, on polyamide layer and cross-linking such that a water-insoluble polymer is formed. Independent claims are included for the following: (1) method for forming a coated composite polyamide reverse osmosis membrane; (2) microporous membrane; and (3) method of producing coated microporous membrane.

Description

Short indication: Selective membrane with a high contamination resistance

BACKGROUND OF THE INVENTION

The present invention relates generally to selective membranes, and more particularly relates to selective membranes with a high contamination resistance.

It is known that dissolved compounds can be separated from their solvents by the use of various types of selective membranes, such as selective membranes including - shown in order of increasing pore size - reverse osmosis membranes, ultrafiltration membranes and microfiltration membranes. An application for which reverse osmosis membranes have previously been used is in the desalination of brackish water or seawater, yielding large volumes of relatively non-salt water suitable for industrial, agricultural or domestic use. What is involved in the desalination of brackish water or seawater using reverse osmosis membranes is literally a filtration of salts and other dissolved ions or molecules from the salt-like water by forcing the salt-like water through a salt-like water. reverse osmosis membrane through which purified water passes through the membrane, while salts and other dissolved ions and molecules do not pass through the membrane Osmotic pressure acts against the reverse osmosis process, and the more concentrated the supply water, the greater the osmotic pressure that must be overcome.

A reverse osmosis membrane must possess certain properties in order to be commercially useful in the large-scale desalination of brackish water or seawater. Such a property is that the membrane must have a high salt rejection coefficient. In fact, in order for the desalted water to be suitable for many commercial applications, the reverse osmosis membrane must have a salt rejection capacity of at least about 97%. Another important property of a reverse osmosis membrane is that the membrane has a high flux property, i.e. the ability to pass a relatively large amount of water through the membrane at relatively low pressures. Typically, the flux for the seawater membrane should be greater than 10 gallons / ft2 day (gfd) at a pressure of 800 psi, and for brackish water should be greater than - 2 - 15 gfd at a pressure of 220 psi. For certain applications, a rejection rate that is less than what would otherwise be desirable may be acceptable in exchange for higher flux and vice versa.

A common type of reverse osmosis membrane is a composite membrane comprising a microporous support and a thin polyamide film formed on the microporous support. Typically, the polyamide film is formed by an interface polymerization of a polyfunctional amine and polyfunctional acyl halide.

An example of the aforementioned composite polyamide reverse osmosis membrane is described in U.S. Patent No. 4,277,344, inventor Cadotte, issued July 7, 1981, and is incorporated herein by reference. The aforementioned patent describes an aromatic polyamide film which is the interface reaction product of an aromatic polyamine with at least two primary amine substituents with an aromatic acyl halide containing at least three acyl halide substituents. In the preferred embodiment, a porous polysulfone support is coated with m-phenylenediamine in water. After removal of excess m-20 phenylenediamine solution from the coated support, the coated support is covered with a solution of trimesoyl chloride dissolved in "FREON" TF solvent (trichlorotrifluoroethane). The contact time for the interfacial reaction is 10 seconds, and the reaction is substantially complete in 1 second. The resulting polysulfone / polyamide composite 25 is then air dried.

Although the Cadotte membrane described above exhibits good flux and good salt rejection, various approaches have been taken to further improve the flux and salt rejection of composite polyamide reverse osmosis membranes. In addition, other approaches have been taken to improve the resistance of the membranes to chemical degradation and the like. Many of these approaches have involved the use of various types of additives to the solutions used in the interfacial polycondensation reaction.

For example, U.S. Patent No. 4,872,984, inventor Tomaschke, issued October 10, 1989 and incorporated herein by reference, describes an aromatic polyamide membrane formed by: (a) coating a microporous support with an aqueous solution comprising : (i) a substantially monomeric, 40 aromatic polyamine reagent with at least two amine functional 3 groups; and (ii) a monofunctional, monomeric (i.e., polymerizable) amine salt to form a liquid layer on the microporous support; (b) contacting the liquid layer with an organic solvent solution of a substantially monomeric, aromatic, amine-reactive reagent comprising a polyfunctional acyl halide or mixture thereof, the amine-reactive reagent averaging at least about 2, Has 2 acyl halide groups per molecule of reagent; and (c) drying the product of step (b) generally in an oven at about 60 ° C to 110 ° C for about 1 to 10 minutes to form a water permeable membrane.

Other patents describing the use of additives in the solutions used in the interfacial polycondensation reaction are: U.S. Patent No. 4,983,291, inventors Chau et al., Issued January 8, 1991; U.S. Patent No. 5,576,057, inventors Hirose et al., Issued November 19, 1996; U.S. Patent No. 5,614,099, inventors Hirose et al., Issued March 25, 1997; U.S. Patent No. 4,950,404, inventor Chau, issued August 21, 1990; U.S. Patent No. 4,830,885, inventors Tran et al., Issued May 16, 1989; U.S. Patent No. 6,245,234, issued to Roo et al., Issued on June 12, 1984, U.S. Patent No. 6,063,278, inventors Koo et al., Issued on May 16, 2000; and U.S. Patent No. 6,015,495, inventors Koo et al., Issued January 18, 2000, all of which are incorporated herein by reference.

Another approach taken to improve the performance of a composite polyamide reverse osmosis membrane is described in U.S. Patent No. 5,178,766, inventors Ikeda et al., Issued January 12, 1993, and which is incorporated herein by reference. According to Ikeda et al., The salt rejection degree of a composite polyamide reverse osmosis membrane would be improved by covalently bonding to the polyamine film of the membrane a compound having a quaternary nitrogen atom. The quaternary nitrogen atom-containing compound is bound to the polyamine film by a reactive group present in the compound, the reactive group being an epoxy group, an aziridine group, an episulfide group, a halogenated alkyl group, an amino group, a carboxylic acid group, a halogenated carbonyl group, or is a hydroxy group.

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A problem encountered by many of the various composite polyamide reverse osmosis membranes described above is fouling, i.e., the undesired adsorption of soluble compounds on the membrane, causing a reduction in flux exhibited by the membrane. Fouling is typically caused by hydrophobic-hydrophobic and / or ionic interactions between the polyamide film of the membrane and those soluble compounds that are present in the solution being filtered. As will be readily understood, fouling is not only undesirable due to the fact that it results in a reduction in flux performance for the membrane, but also since it requires operating pressures to be frequently varied to compensate for the variations in flux experienced during the flux. Reduction. In addition, contamination also requires frequent cleaning of the membrane. .

An approach to the problem of fouling is described in U.S. Patent No. 6,177,011, inventors Hachisuka et al., Issued January 23, 2001, and incorporated herein by reference.

According to Hachisuka et al., Fouling can be reduced by coating the polyamide film of the membrane with at least one compound selected from the group consisting of an electrically neutral organic compound and a polymer that has a non-ionic hydrophilic group, the organic compound or the polymer is preferably a polyvinyl alcohol.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a new fouling resistant, selective membrane.

It is another object of the present invention to provide a novel composite polyamide reverse osmosis membrane that has high fouling resistance.

The present invention is based on the unexpected finding that the resistance of a composite polyamide reverse osmosis membrane to fouling can be significantly improved by treating the membrane with a hydrophilic coating wherein the hydrophilic coating is made by: (i) applying on the membrane of an amount of polyfunctional epoxy compound, wherein the polyfunctional epoxy compound is.

- comprises at least two epoxy groups; and (ii) then cross-linking the polyfunctional epoxy compound in such a way that a water-soluble polymer is obtained. Typically, the cross-linking step comprises opening the epoxy groups by nucleophilic attack to yield an ether or an alcohol.

When the polyfunctional epoxy compound has exactly two epoxy groups, the cross-linking step comprises binding the polyfunctional epoxy compound to a cross-linking compound, wherein the cross-linking compound comprises at least three epoxy-reactive groups (although it should be noted that a polyfunctional epoxy compound with exactly two epoxy groups also can be cross-linked by a diamino compound with two primary amino groups, two secondary amino groups, or a primary amino group and a secondary amino group). On the other hand, when the polyfunctional epoxy compound has three or more epoxy groups, the cross-linking step comprises the self-polymerization of the polyfunctional epoxy compound and / or binding the polyfunctional epoxy compound to a cross-linking compound comprising at least two epoxy-reactive compounds.

The present invention also relates to a process for freezing of the composite polyamide reverse osmosis membrane described above with a coating having a high contamination resistance.

The present invention further relates to microfiltration membranes and ultrafiltration membranes which contain the coating with high pollution resistance according to the present invention, as well as to a method for the manufacture of such coated membranes.

Additional objects, features, aspects and advantages of the present invention will be set forth in part in the description which follows and in part will be apparent from the description or may be learned by practice of the invention. Certain embodiments of the invention will be discussed in sufficient detail below to enable those skilled in the art to review the invention, and it is to be understood that other embodiments may be used and that structural or other changes may apply. without departing from the scope of the invention. The following detailed description is therefore not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As stated above, the present invention is based on the unexpected finding that the fouling resistance of a selective membrane, such as a composite polyamide reverse osmosis membrane, a microfiltration membrane or an ultrafiltration membrane can be significantly increased by treating the membrane with a hydrophilic coating, the hydrophilic coating being made by: (i) applying to the membrane an amount of a polyfunctional epoxy compound, wherein the polyfunctional epoxy compound comprises at least two epoxy groups; and (ii) subsequently cross-linking the polyfunctional epoxy compound in such a way that a water-insoluble polymer is obtained.

The composite polyamide reverse osmosis membrane on which the hydrophilic coating of the present invention is applied can be almost any composite polyamide reverse osmosis membrane of the type comprising a porous support and a polyamide film applied to the porous support.

The aforementioned porous support is typically a microporous support. The particular microporous support used is not crucial to the present invention, but is generally a polymeric material that contains pore sizes that are of a size sufficient to allow permeate passage therethrough, but not large enough to interfere with the bridging of the ultra-thin membrane formed on it. The pore size of the support will generally be between 1 and 500 nanometers, since pores with a diameter larger than 500 nanometers will cause the ultra-thin film to sink into the pores, thereby disrupting the desired flat plate configuration. Examples of microporous carriers useful in the present invention include those made from a polysulfone, a polyether sulfone, a polyimide, a polyamide, a polyethermide, polyacrylonitrile, poly (methyl methacrylate), polyethylene, polypropylene, and various halogenated polymers such as polyvinylidene fluoride. Additional microporous support materials can be found in the patents 40 incorporated herein by reference.

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The thickness of the microporous support is not crucial to the present invention. In general, the thickness of the microporous support is approximately 25 to 125 µm, preferably approximately 40 to 75 µm.

The polyamide film of the present invention is typically the interface reaction product of a polyfunctional amine reagent and a polyfunctional amine reactive reagent. The polyfunctional amine reagent used in the present invention is preferably a substantially monomeric amine with at least two amine functional groups, more preferably 2 to 3 amine functional groups. The amine functional group is typically a primary or secondary amine functional group, preferably a primary amine functional group. The particular polyamine used in the present invention is not crucial to it and may be a single polyamine or a combination thereof. Examples of suitable polyamines are aromatic primary diamines, such as meta-phenylenediamine and para-phenylenediamine and substituted derivatives thereof, wherein the substituent is for example an alkyl group, such as a methyl group or an ethyl group, an alkoxy group, such as a methoxy group or an ethoxy group, a hydroxyalkyl group , a.

- - ----- hydroxy group or a halogen atom. Additional examples of suitable polyamines are alkanediamines, such as 1,3-propanediamine and its homologues with or without N-alkyl or aryl substituents, cycloaliphatic primary diamines, such as cyclohexanediamine, cycloaliphatic secondary diamines such as piperazine and its alkyl derivatives, aromatic secondary amines such as N, N'-dimethyl-1,3-phenylenediamine, N, N'-diphenylethylenediamine, benzidine, xylylenediamine and derivatives thereof. Other suitable polyamines can be found in the patents incorporated herein by reference. The preferred polyamines of the present invention are aromatic primary diamines, more preferably m-phenylenediamine, and piperazine. (A composite polyamide reverse osmosis membrane made using piperazine as the polyfunctional amine reagent 35 falls within a subclass of composite polyamide reverse osmosis membranes known as nanofiltration membranes. Nanofiltration membranes have larger "pores" than other composite polyamide reverse osmosis membranes and exhibit a low rejection rate of monovalent salts, while showing a high rejection rate of bivalent salts and organic materials with a molecular weight greater than 300. Nanofiltration membranes are typically used to remove calcium and magnesium salts from water, ie to soften hard water, and to remove natural organic material from water, such as humic acids from rotting plant leaves Humic acid is negatively charged at a pH above 6 and can be adsorbed on the membrane through hydrophobic interactions with the membrane surface.

The polyfunctional amine reagent is typically present in an aqueous solution in an amount of between about 0.1 and 20%, preferably 0.5 to 8%, by weight, of the aqueous solution. The pH of the aqueous solution is in the range of about 7 to 13. The pH can be adjusted by the addition of a basic acid acceptor in an amount in the range of about 0.001% to about 5% by weight of the solution.

Examples of the aforementioned basic acid acceptor are hydroxides, catboxylates, carbonates, borates, phosphates of alkali metals and trialkylamines.

In addition to the aforementioned polyfunctional amine reagent (and if desired the aforementioned basic acid acceptor), the aqueous solution may further comprise additives of the type described in the patents incorporated herein by reference, such additives being, for example, polar solvents, amine salts and polyfunctional tertiary amines (in the presence or absence of a strong acid).

The polyfunctional amine reactive reagent used in the present invention is one or more compounds selected from the group consisting of a polyfunctional acyl halide, a polyfunctional sulfonyl halide and a polyfunctional isocyanate. Preferably, the polyfunctional amine reactive reagent is a substantially monomeric, aromatic, polyfunctional acyl halide, examples of which are di- or tricarboxylic acid halides, such as trimesoyl chloride (TMC), isophthaloyl chloride (IPC), terephthaloyl chloride (TPC) and mixture thereof. Examples of other polyfunctional amine-reactive reagents are described in the patents incorporated herein by reference.

The polyfunctional amine-reactive reagent is typically present in an organic solvent solution, the solvent for the organic solvent solution comprising any organic liquid that is immiscible with water. The polyfunctional 40 amine reactive reagent is typically present in the 1 p. O r, iUii "w C, ij: ·; ? organic liquid in an amount in the range of about 0.005 to 5% by weight, preferably 0.01 to 0.5% by weight of the solution. Examples of the aforementioned organic liquids are hexane, cyclohexane, heptane, alkanes with 8 to 12 carbon atoms, and 5 halogenated hydrocarbons such as the FREON series. Other examples of the organic liquids described above can be found in the patents incorporated herein by reference. Preferred organic solvents are alkanes with 8 to 12 carbon atoms and mixtures thereof. ISOPAR® solvent (Exxon Corp.) is such a mixture of alkanes with 8 to 12 carbon atoms.

According to the teachings of the present invention, an uncoated composite polyamide reverse osmosis membrane is prepared as follows: first, the porous support described above is coated with the above-described aqueous solution using a hand coating or continuous processing, and the excess solution is removed from the support by rolling, sponging, air knife machining or other suitable techniques. After this, the coated support material is then brought into contact, for example by dipping or spraying, with the "organic" solvent solution described above, and then allowed to stand for a period of time in the range of about 5 seconds to about 10 minutes, preferably about 20 seconds to 4 minutes. The resulting product is then dried at a temperature below 50 ° C, preferably by air drying at room temperature for about 1 minute, then rinsed in a basic aqueous solution such as a 0.2% sodium carbonate solution, for about 1 to 30 minutes at about room temperature to 95 ° C, and then rinsed with deionized water.

While the above-described composite polyamide reverse osmosis membrane is preferably still wet by being rinsed with deionized water, the hydrophilic coating of the present invention is then formed on the membrane by: (i) applying to the polyamide film of the membrane of an amount of a polyfunctional epoxy compound, wherein the polyfunctional epoxy compound comprises at least two epoxy groups; and (ii) then cross-linking the polyfunctional epoxy compound in such a way as to yield a water-insoluble polymer. The cross-linking step is very important since the polyfunctional epoxy compound, in the absence of cross-linking, is water-soluble and will thus be washed off the membrane during use.

When the polyfunctional epoxy compound has exactly two epoxy groups, the cross-linking step comprises binding the polyfunctional epoxy compound to a cross-linking compound with at least three epoxy-reactive groups. Such a cross-linking compound is necessary, since the self-polymerization of a polyfunctional epoxy compound with exactly two epoxy groups yields a linear ladder-type polymer that is water-soluble, and thus not on it. membrane will remain in use (although it should be noted that a polyfunctional epoxy compound with exactly two epoxy groups can also be cross-linked by a diamino compound with two primary amino groups, two secondary amino groups or a primary amino group 15 and a secondary amino group). In contrast, when the polyfunctional epoxy compound has three or more epoxy groups, the crosslinking step includes the self-polymerization of the polyfunctional epoxy compound and / or binding the polyfunctional epoxy compound to a crosslinking compound with at least two epoxy-reactive groups. In the light of the above, it should be understood that a polyfunctional epoxy compound with exactly two epoxy groups can be polymerized with a polyfunctional epoxy compound with three or more epoxy groups.

Typically, the cross-linking step comprises opening the epoxy groups by nucleophilic attack, wherein the oxygen atom of the epoxy ring is used to form an ether or an alcohol. The crosslinking can be catalyzed by a base catalyst, by an acid catalyst or by heat. Examples of the base catalyst are alkoxide salts, such as sodium ethoxide; Hydroxide salts, such as sodium hydroxide and potassium hydroxide; carbonate salts, such as potassium carbonate; phosphate salts such as trisodium phosphate; phenoxide salts, such as sodium phenoxide; borate salts such as sodium borate; carboxylate salts, such as potassium acetate; ammonia; and primary, secondary and tertiary amines. The acid catalyst can be an inorganic acid, an organic acid or a Lewis acid. More specifically, examples of the acid catalyst are sulfuric acid; hydrochloric acid; nitric acid; an aromatic sulfonic acid; an aliphatic sulfonic acid; a cycloaliphatic sulfonic acid; a carboxylic acid; a fluorinated carboxylic acid such as 40 trifluoroacetic acid; phenol and its derivatives; boric acid; 11 tetrafluoroboric acid; aluminum trihalide; an aluminum trialkoxide; a boron trihalide, such as boron trifluoride; zinc trafluoroborate; a tin tetrahalide such as tin tetrachloride; a quaternary ammonium salt; and an acid salt of ammonia or a primary, secondary or tertiary amine.

Heat catalysis may include, for example, heating the coating to 10 ° C to 200 ° C, preferably 20 ° C to 150 ° C, for a period of about 1 second to 7 days, preferably about 5 seconds to 3 days.

Examples of polyfunctional epoxy compounds with exactly two epoxy groups for use in the present invention are: ethylene glycol diglycidyl ether; propylene glycol diglycidyl ether; 1,3-propanediol diglycidyl ether; 1,3-butanediol diglycidyl ether, 1,4-butanediol diglycidyl ether; 1,5-pentanediol diglycidyl ether; 1,2-pentanediol diglycidyl ether; 2,4-pentanediol diglycidyl ether; 1,6-hexanediol diglycidyl ether; 1,2-hexanediol diglycidyl ether; 1,5-hexanediol diglycidyl ether; 2,5-hexanediol diglycidyl ether; 2-ethyl-1,3-hexanediol diglycidyl ether; 1,7-dipanediol diglycidyl ether; 1,2-octanediol diglycidyl ether; 1,8-octanediol diglycidyl ether; 1,9-nonanediol diglycidyl ether; 1,10-decanediol diglycidyl ether; 1,2-deca'ahdl o 1 cligTyc Γά yTe the r; 1, 2 - dead ca 1, 1, 1 or cfidyl ether; 1,2-dodecanediol diglycidyl ether; glycerol diglycidyl ether; trimethylolpropane diglycidyl ether; 1,1,1-tris (hydroxymethyl) ethanediglycidyl ether; pentaerythritol diglycidyl ether; sorbitol diglycidyl ether; Neopentyl glycol diglycidyl ether; dibromo neopentyl glycol diglycidyl ether; hydroquinone diglycidyl ether; resorcinol diglycidyl ether; bisphenol A diglycidyl ether; hydrogenated bisphenol A diglycidyl ether; polyethylene glycol diglycidyl ether with the repeating ethylene glycol unit (CH 2 CH 2 O) n where n is an integer in the range of 2 to 400; and polypropylene glycol diglycidyl ether with the repeating propylene glycol unit ((CH 3) CH 2 CH 2 O) n, wherein n is an integer in the range of 2 to 100.

Examples of polyfunctional epoxy compounds with exactly three epoxy groups for use in the present invention are glycerol triglycidyl ether; diglycerol triglycidyl ether; pentaerythri-toll triglycidyl ether; sorbitol triglycidyl ether; glycerol propoxylate triglycidyl ether; trimethylolpropane triglycidyl ether; 1,1,1-tris (hydroxymethyl) ethane triglycidyl ether; 1,1,1-tris (hydroxyphenyl) ethane triglycidyl ether; tris (hydroxymethyl) nitromethane triglycidyl-40 ether; tris (2,3-epoxypropyl) isocyanurate; phloroglucinol triglycidyl ether; N, N-diglycidyl-4-glycidylolxyaniline; a reaction product of epichlorohydrin and 1,3,5-tris (2-hydroxyethyl) cyanuric acid; and a reaction product of epichlorohydrin and tris (hydroxymethyl) amino methane.

Examples of polyfunctional epoxy compounds with exactly four epoxy groups for use in the present invention are sorbitol tetraglycidyl ether; pentaerythritol tetraglycidyl ether; polyglycerol tetraglycidyl ether; and 4,4'-methylenebis (N, N-diglycidylaniline).

Examples of polyfunctional epoxy compounds with four epoxy groups for use in the present invention are sorbitol pentaglycidyl ether; sorbitol hexaglycidyl ether; polyglycerol polyglycidyl ether; epoxycresol novolac resin; reaction products of polyvinyl alcohol and epichlorohydrin; reaction products of polyvinyl phenol and epichlorohydrin; reaction products of polyacrylamide and epichlorohydrin; and reaction products of epichlorohydrin and cellulose and their derivatives, such as hydroxyethyl cellulose and hydroxypropyl cellulose.

It should be noted that all the polyfunctional epoxy compounds shown above are the reaction product of epichlorohydrin and a polyfunctional hydroxy, amino and / or amide compound, the reaction preferably being catalyzed with sodium hydroxide. Examples of such polyfunctional hydroxy, amino and / or amide compounds are: ethylene glycol; Propylene glycol; 1,3-propanediol; 1,3-butanediol, 1,4-butanediol; 1,5-pentanediol; 1,2-pentanediol, 2,4-pentanediol; 1,6-hexanediol; 1,2-hexanediol; 1,5-hexanediol; 2,5-hexanediol; 2-ethyl-1,3-hexanediol; 1,7-heptanediol; 1,2-octanediol; 1,8-octanediol; 1,9-nonanediol; 1,10-decanediol; 1,2-decanediol; 1,12-dodecanediol; 1.2-30 dodecanediol; glycerol; trimethylolpropane; 1,1,1-tris (hydroxymethyl) ethane; tris (hydroxymethyl) aminomethane; 1,3,5-tris (2-hydroxyethyl) cyanuric acid; pentaerythritol; sorbitol; neopentyl glycol; dibromo neopentyl glycol; hydroquinone; resorcinol; bisphenol A; hydrogenated bisphenol A; isocyanuric acid; 35 floroglucinol; methylenebisaniline; novolak resin; polvinyl alcohol; polyvinyl phenol; polyacrylamide; cellulose and its derivatives, such as hydroxyethyl cellulose and hydroxypropyl cellulose; chitosan; polyethylene glycol with the repeating ethylene glycol unit (CH 2 CH 2 O) n where n is in the range of 2 to 400; and ·; . · '· ·; ·. ··; ·> t • * -J L ·. Polypropylene glycol with the repeating propylene glycol unit ((CH3) CH2 CH2 O) where n is in the range of 2 to 100.

In light of the above, it will be readily understood that the polyfunctional epoxy compound of the present invention could be formed in the aforementioned manner by first reacting epichlorohydrin and a polyfunctional compound of the type described above, and then applying the resulting reaction product to the polyamide film of the membrane; instead, the polyfunctional epoxy compound could be formed in situ on the polyamide film of the membrane by applying (in the presence of a suitable catalyst) the combination of epichlorohydrin and a suitable polyfunctional reagent.

As noted above, when a cross-linking compound is used to cross-link polyfunctional epoxy compounds with three or more epoxy groups, the cross-linking compound must have two or more epoxy-reactive groups, and when a cross-linking compound is used to cross-link polyfunctional epoxy compounds with exactly two epoxy groups the crosslinking compound have three or more epoxy-reactive groups. (Although as noted above, a polyfunctional epoxy compound with exactly two epoxy groups can also be cross-linked by a diamino compound with two primary amino groups, two secondary amino groups, or a primary amino group and a secondary amino group. This is since the primary and secondary amino groups, after the reacting with an epoxy group become secondary and tertiary amino groups, which can still react with an additional epoxy group). Examples of epoxy-reactive groups that are suitable for use in the crosslinking of compounds of the present invention are hydroxy groups; amino groups including primary, secondary and tertiary amines; carboxyl groups; carboxylic anhydride groups; amide groups; carbonyl groups including aldehyde groups and urea groups; and sulfurhydryl (thiol) groups. The two or more epoxy-reactive groups of a cross-linking compound according to the present invention can be the same type of epoxy-reactive group or can be a combination of different types of epoxy-reactive groups.

Examples of compounds that have exactly two epoxy-reactive groups, both of which are hydroxy groups, and suitable for use in the present invention as crosslinking compounds are: ethylene glycol; propylene glycol; 1,3-propanediol; 1,3-butanediol; 1,4-butanediol; 1,5-pentanediol; 1,2-pentanediol; 2,4-pentanediol; 1,6-hexanediol; 1,2-hexanediol; 1,5-hexanediol; 2,5-hexanediol; 2-ethyl-1,3-hexanediol; 1,7-heptanediol; 1,2-octanediol; 1,8-octanediol; 1,9-nonanediol; 1,10-decanediol; 1,2-decanediol; 1,12-dodecanedioi; 1,2-dodecanediol; neopentyl glycol; dibromo neopentyl glycol; hydroquinone; resorcinol; bisphenol A; hydrogenated bisphenol A; polyethylene glycol with the repeating ethylene glycol unit (CH 2 CH 2 O) n where n is in the range of 2 to 400; and polypropylene glycol with the repeating ethylene glycol unit ((CH3) CH2 CH2) n where n is in the range of 2 to 100.

Examples of compounds that have more than two epoxy-reactive groups, all of which are hydroxy groups, and are suitable for use in the present invention as crosslinking compounds are: glycerol; trimethylolpropane; 1,1,1-tris (hydroxymethyl) ethane; 1,1,1-tris (hydroxyphenyl) ethane; tris (hydroxymethyl) -aminomethane; tris (hydroxymethyl) nitromethane; 1,3,5-tris (2-hydroxyethyl) cyanuric acid; pentaerythritol; sorbitol; glucose; Fructose; maltose; mannose; glucosamine; mannosamine; a polysaccharide such as sucrose; isocyanuric acid; . phloroglucinol; methylenebisaniline; novolak resin; polyvinyl alcohol; polyvinyl phenol; polyacrylamide; and cellulose and its derivatives, such as hydroxyethyl cellulose, hydroxypropyl cellulose, ethyl cellulose and methyl cellulose.

Examples of compounds that have exactly two epoxy-reactive groups, both of which are amino groups (which may be primary, secondary and / or tertiary amino groups), and are suitable for use in the present invention as crosslinking compounds (e.g. with polyfunctional epoxy compounds with three or more epoxy groups), alkane diamines and their alkyl or aryl derivatives on nitrogen and skeletal carbon atoms are of the types shown below: H 2 N (CH 2) n NH 2 wherein n. = 2-12; H 2 N (CH 2 CH 2 O) n CH 2 CH 2 NH 2 where n = 35 1-400;

R 1 R 2 N (CH 2) 'NR 3 R 4 wherein n = 2-12 and R 1, R 2, R 3 and R 4 are the same or different and are selected from the group consisting of hydrogen, methyl, ethyl, propyl, butyl, cyclohexyl and phenyl of which examples N, N, N ', N'-tetramethyl-1,4-butanediamine, N, N, N', N '-1.

- tetramethyl-1,6-hexanediamine, N, N, N ', N'-tetramethyl-1,3-propanediamine and N, N, N', N'-tetramethyl ethylenediamine; R 1, R 1, R 5, H 2 CH 2 and R 2 O 2, R 3, R 2, R 4 and R 5 are the same or different and are selected from the group consisting of hydrogen, methyl, ethyl, propyl, butyl , cyclohexyl, hydroxyl and phenyl, examples of which are Ν, Ν, Ν ', Ν'-tetramethyl-1,3-butanediamine, and N, N, N', N'-tetramethyl-1,3-diamino-2-propanol to be;

Alicyclic diamines selected from the group consisting of diaminocyclohexane; 1,3-cyclohexane bis (methylamine); 4,4'-trimethylenedipiperidine; piperazine; 1,4-dimethyl piperazine; 1,4-diazabicyclo [2.2.2] octane; 1,8-diazabi-cyclo [5.4.0] undec-7-ene; 1.5-15 diazabicyclo [4.3.0] non-5-ene; and

Aromatic diamines selected from the group consisting of meta-phenylenediamine; meta-xylylenediamine; and bis (4-amino-phenyl) sulfone.

Other examples of suitable diamino compounds are Ν, Ν, Ν ', N'-tetramethyl-2-butene-1,4-diamine, which is comparable to the aforementioned N, N, N', N'-tetramethyl-1 4-butanediamine, with the difference that it has a double bond in the skeleton.

Examples of compounds that have three or more epoxy-reactive groups wherein all three or more epoxy-reactive groups are amino groups (which may be primary, secondary and / or tertiary amino groups) and are suitable for use in the present invention as crosslinking compounds : N, N'-bis (2-aminoethyl) -1,3-propanediamine, diethylene triamine, triethylene tetramine; tris (2-aminoethyl) amine; Ν, Ν, Ν'Ν ', N "-penta-methyldiethylenetriamine; triaminobenzene; 1,1,3,3-tetramethylguanidine; polyethyleneiminel; chitosan; poly (allylamine); and polyvinylpyridine.

Membrane coatings of the present invention prepared using cross-linking compounds containing amino groups can impart a total positive charge to the membrane (depending on the number of amino groups actually included in the coating). As a result, such coated membranes can have good fouling resistance to positively charged dissolved compounds, and thus may be particularly well suited to treating, for example, 40 water-containing, positively-charged compounds of some hydrophobic nature, such as cationic surfactants . For comparison, membrane coatings made with anionic crosslinking compounds having both hydroxy and acidic or anionic groups, such as tartaric acid; gluconic acid; glucuronic acid; 3,5-dihydroxybenzoic acid; 2,5-dihydrobenzene sulfonic acid potassium salt; and 2,5-dihydroxy-1,4-benzenedisulfonic acid dipotassium salt impart a total negative charge to the membrane. As a result, such coated membranes can be particularly well suited for treating, for example, water-containing, negatively charged, dissolved compounds. On the other hand, membrane coatings made using cross-linking compounds containing neutral groups such as hydroxy groups, amide groups, and carbonyl groups result in a more neutrally charged membrane. As a result, such a coated membrane 15 can be more universally applicable for treating water containing positively charged or negatively charged material. Finally, a membrane coating with both negative and positive charges can be made using cross-linking compounds with zwitter ions. Examples of such compounds are: 3,5-diaminobenzoic acid; 2-aminoethanesulfonic acid (taurine); 2- {[tris (hydroxymethyl) methyl] amino} -1-ethanesulfonic acid; 3 - {[tris- (hydroxymethyl) methyl] amino} -1-propane sulfonic acid; 2-hydroxy-3- {[tris (hydroxymethyl) methyl] amino} -1-propane sulfonic acid; fi-hydroxy-4- (2-hydroxyethyl) -1-piperazine propanesulfonic acid; β, β'-dihydroxy-1,4-25 piperazine bis (propane sulfonic acid); and 2,5-diaminobenzene sulfonic acid. In any case, it can be seen from the above discussion that the charge of the membrane coating can be controlled to exhibit high resistance to contamination by variously charged or uncharged soluble compounds.

When the polyfunctional epoxy compound is first formed and then applied to the membrane, the polyfunctional epoxy compound is preferably applied to the membrane as part of a coating solution comprising the polyfunctional epoxy compound and a solvent of water and / or an alcohol. In such a coating solution, the polyfunctional epoxy compound is typically present in an amount in the range of about 0.00001% to 20% by weight of the solution, preferably about 0.0001% to 5% by weight of the solution (a crosslinker is also preferably included in the coating solution if required). The coating solution is then sprayed with

"/ · / - * · -V

A T-die which is coated, meniscus-coated or cloth-coated on the upper surface of the polyamide film of the membrane for a period of approximately 1 second to 10 minutes, preferably approximately 5 seconds to 5 minutes. heat crosslinking is catalyzed, the coated membrane is then dried and cured at 10 ° C to 200 ° C, preferably 20 ° C to 150 ° C, for a period of about 1 second to 7 days, preferably about 5 seconds to 3 days.

As noted above, the hydrophilic coating of the present invention is not limited to use with composite, polyamide reverse osmosis membranes, but can also be applied directly to conventional microporous membranes, such as micro-filtration membranes and ultra-filtration membranes, to prevent their contamination by proteins, macromolecules and colloids. to withstand when such membranes are used in surface water treatment, protein separations, and food and beverage processing. A conventional microfiltration membrane is typically a microporous support of the type described above that has a pore size of about 0.1 μ - 10 μ. A conventional ultrafiltration membrane is typically a microporous support of the type described above that has a pore size of about 0.001 μ - 0.05 μ.

The following examples are provided for illustrative purposes only and are not intended to limit the scope of the present invention in any way.

EXAMPLE 1

A 140 µm thick microporous polysulfone carrier containing the supporting non-woven fabric was left for 40 seconds. immersed in an aqueous solution containing 2% by weight of meta-phenylenediamine (MPD) and 0.3% by weight of 2-ethyl-1,3-hexanediol. The support was drained, and rolled with a pinch while removing the excess aqueous solution. Subsequently, the coated support was dipped in 0.1 wt.% Solution of trimesoyl chloride (TMC) in Isopar® solvent (Exxon Corp.) for 1 min, followed by draining the excess organic solution from the support. The resulting composite membrane was air dried for about 1 minute, then in 0.2% aqueous solution for 30 minutes.

Na2 CO3 solution rinsed at room temperature, and then rinsed in deionized water.

The resulting membrane was then sprayed on its upper surface (ie on the polyamide film) for 20 seconds with an aqueous solution containing 0.1 wt% of sorbitol tetraglycidyl ether, 0.04 wt% of N, .N, N ', N tetramethyl-1, 6-hexanediamine (TMHD) and 3 wt% glycerol (as a wetting agent), and then drained to remove the excess aqueous solution. The membrane was then heated at 50 ° C for 4 minutes, followed by air drying for one day. The initial performance of the membrane was measured by passing an aqueous solution containing 2000 ppm of NaCl through the membrane in a cross-flow mode at 225 psi and 25 ° C. The salt rejection was 99% and the flux was 22 gfd. The fouling resistance of the membrane was then evaluated under the same conditions described above, by further adding 30 ppm of dry milk to the feed water. (The dry milk protein in an aqueous solution can be present as protein molecules and colloids, i.e. aggregates of protein molecules, and can be adsorbed to the membrane through hydrophobic interactions with the membrane surface). After circulating the feed water through the membrane for 4 hours, the salt rejection was 99.4% and the flux was 17.6 gfd. Table 1 shows the data described above, as well as the corresponding data obtained from an otherwise identical membrane to which no coating was added (Comparative Example 1).

$ 0 ^ - <··: Γ. Π - 19 - TABLE 1

Membrane Initial Initial Final Flux in the Flux salt rejection flux presence of decrease (%) (gfd) the dry milk (%) (gfd)

Comparative 99 29 15.7 46 Example 1

Example 1 99 22.3 17.4 22

As can be seen, the coated membrane (Example 1) exhibited a considerably smaller decrease in flux than the non-coated membrane (Comparative Example 1). This is advantageous since, as noted above, a consistency in flux over a long period of time is highly desirable, since it avoids the requirement to continuously vary the operating pressure and wash the membrane to remove contaminants therefrom. It should also be recognized that while the final flux for the present example was measured only after 4 hours of use, such membranes are expected. that they are used continuously for considerably longer periods of time. Accordingly, the final flux values given above are much more representative of the flux properties of the membranes over their respective service lives than the initial flux values are.

It should also be noted that when the coated membrane was washed after its 4-hour use period, its flux returned substantially to the initial flux, while the non-coated membrane when washed after its 4-hour use period , only approached about 80% of the initial flux.

EXAMPLE 2

The same procedure as set forth in Example 1 was performed for Example 2 with the difference that 0.05% by weight of 2,5-dihydroxybenzene sulfonic acid potassium salt was used instead of TMHD. The performance of the resulting membrane, as well as an otherwise identical membrane to which no coating was added (Comparative Example 2) are shown in Table 2.

- 20 - TABLE 2

Membrane Initial Initial Final Flux in the Flux salt rejection flux (gfd) presence of decrease (%) dry milk (gfd) (%)

Comparison 99 27.3. 22.5 17.6 example 2

Example 2 99.4 23.2 20.9 9.9

As can be seen, the coated membrane exhibited a considerably smaller decrease in flux than did the uncoated membrane.

EXAMPLE 3

The same procedure as set forth in Example 1 was performed for Example 3 except that 0.2% by weight of glycerol triglycidyl ether and 0.04% by weight of 2,2 '- (ethylenedioxy) bis (ethylamine) were used instead of sorbitol tetraglycidyl ether and TMHD, respectively. The performance of the resulting membrane, as well as an otherwise identical membrane to which no coating was added (Comparative Example 3) are shown in Table 3.

TABLE 3

Membrane Initial Initial Final Flux in the Flux salt rejection flux (gfd) presence of decrease (%) dry milk (gfd) (%)

Comparative 97 51.7 25.8 46.8 Example 3

Example 3 97.7 39.2 23.5 32.6

As can be seen, the coated membrane exhibited a considerably smaller decrease in flux than did the uncoated membrane.

EXAMPLE 4

The same procedure as set forth in Example 1 was performed for Example 4 with the difference that 0.25% by weight polyethylene glycol diglycidyl ether and 0.025% by weight polyethylene imine were used instead of sorbitol tetraglycidyl ether, respectively. and TMHD. The performance of the resulting 5 '- 21 membrane, as well as an otherwise identical membrane to which no coating was added (Comparative Example 4) are shown in Table 4.

5 TABLE 4

Membrane Initial Initial Final Flux in the Flux salt rejection flux (gfd) presence of decrease (%) dry milk (gfd) (%)

Equation 97 51.7 25.8. 46.8 example 4

Example 4 97 31.7 23.6 22.6

As can be seen, the coated membrane exhibited a considerably smaller decrease in flux than did the uncoated membrane.

EXAMPLE 5

The same procedure as set forth in Example 1 was carried out for Example 5 with the difference that 1.1% by weight of polyethylene glycol diglycidyl ether and 0.05% by weight of trifluoroacetic acid and 3% by weight of glycerol became a crosslinking agent and also as a wetting agent) used instead of sorbitol tetraglycidyl ether and TMHD, respectively. The performance of the resulting membrane as well as of an otherwise identical membrane to which no coating was added (Comparative Example 5) are shown in Table 5.

TABLE 5

Membrane Initial Initial Final Flux in the Flux salt rejection flux (gfd) presence of decrease (%) dry milk (gfd) (%)

Comparative 97.2 40.9 29.8 25.5 Example 5

Example 5 98.3 21.7 21.5 4.4

As can be seen, the coated membrane exhibited a considerably smaller decrease in flux than did the uncoated membrane.

- EXAMPLE 6

The same procedure as set forth in Example 1 was performed for Example 6 except that 0.15% by weight of sorbitol tetraglycidyl ether, 0.06% by weight of TMHD and 2% by weight of glycerol were used instead of the corresponding amounts. of those used in Example 1. In addition, 50 ppm of dodecyl trimethyl ammonium bromide (DTAB), a cationic surfactant, was used instead of dry milk as the fouling (DTAB can be adsorbed to the membrane by hydrophobic and / or ionic interactions with the membrane). The performance of the resulting membrane, as well as of an otherwise identical membrane to which no coating was added (Comparative Example 6) are shown in Table 6.

TABLE 6

Membrane Initial Initial Final Flux in the Flux salt rejection flux (gfd) presence of decrease (%) DTAB (gfd) (%)

Comparative 97 55.2 28.5 48.3 Example 6

Example 6 97.6 33.6 2779 17.1

As can be seen, the coated membrane exhibited a considerably smaller decrease in flux than did the uncoated membrane.

EXAMPLE 7

Ten water drops were placed on an uncoated membrane prepared in the manner described in Example 1, and the contact angle for each such water drop on the uncoated membrane was measured. Next, the coating described in Example 1 was applied to the membrane, and ten water drops were placed on the coated membrane, the contact angle for each such water drop being measured. The average measured contact angles for the drops on the uncoated membrane and the coated membrane were 55.6 degrees and 48.8 degrees, respectively. These results indicate that the coated membrane is more hydrophilic than the non-coated membrane, since the coated membrane caused the water droplets to spread more on the membrane; -309 - 23 - while the uncoated membrane caused the water droplets to stick together on the membrane.

The embodiments of the present invention mentioned herein are intended to merely illustrate the invention, and those skilled in the art will be able to make numerous variations and modifications to it without departing from the scope of the present invention. . All such variations and modifications are intended to fall within the scope of the present invention as defined by the appended claims.

"Λ

Claims (34)

A composite polyamide reverse osmosis membrane comprising: (a) a microporous support; (b) a polyamide layer on the microporous support; and (c) a hydrophilic coating on the polyamide layer, the hydrophilic coating being prepared by: (i) applying to the polyamide layer an amount of a polyfunctional epoxy compound, wherein the polyfunctional epoxy compound comprises at least two epoxy groups; and (ii) then cross-linking the polyfunctional epoxy compound in such a way that a water-insoluble polymer is obtained. 2. Composite polyamide reverse osmosis membrane according to claim 1, wherein the microporous support is made from a material selected from the group consisting of a polysulfone, a polyether sulfone, a polyimide, a polyamide, a polyetherimide, polyacrylonitrile, poly (methyl methacrylate), polyethylene , polypropylene and a halogenated polymer. The composite polyamide reverse osmosis membrane according to claim 1, wherein the polyamide layer is the interface reaction product of a polyfunctional amine and polyfunctional amine reactive reagent. 4. Composite polyamide reverse osmosis membrane according to claim 3, wherein the polyfunctional amine is at least one member selected from the group consisting of an aromatic, primary diamine and substituted derivatives thereof; an alkane primary diamine, a cycloaliphatic primary diamine, a cycloaliphatic secondary diamine, an aromatic secondary diamine and a xylylenediamine. The composite polyamide reverse osmosis membrane according to claim 3, wherein the polyfunctional amine reactive reagent is at least one compound selected from the group consisting of a polyfunctional acyl halide, a polyfunctional sulfonyl halide and a polyfunctional isocyanate. The composite polyamide reverse osmosis membrane according to claim 1, wherein the polyfunctional epoxy compound comprises at least three epoxy groups. 1020950 * - 25 - The composite polyamide reverse osmosis membrane according to claim 6, wherein the polyfunctional epoxy compound is at least one compound selected from the group consisting of glycerol triglycidyl ether; digiycerol triglycidyl ether; pentaerythri-5-toltriglycidyl ether; sorbitol triglycidyl ether; glycerol propoxylate triglycidyl ether; trimethylolpropane triglycidyl ether; 1,1,1-tris (hydroxymethyl) ethane triglycidyl ether; 1/1/1-tris (hydroxyphenyl) ethane triglycidyl ether; tris (hydroxymethyl) nitromethane triglycidyl ether; tris (2,3-epoxypropyl) isocyanurate; phloroglucinol triglycidyl ether; N, N-diglycidyl-1,4-glycidyloxyaniline; a reaction product of epichlorohydrin and 1,3,5-tris (2-hydroxyethyl) cyanuric acid; a reaction product of epichlorohydrin and tris (hydroxymethyl) aminomethane; sorbitol tetraglycidyl ether; pentaerythritol tetraglycidyl ether; polyglycerol tetraglycidyl ether; and 4,4'-methylenebis-15 (N, N-diglycidylaniline); sorbitol pentaglycidyl ether; sorbitol hexa glycidyl ether; polyglycerol polyglycidyl ether; epoxycresol novolac resin; a reaction product of polyvinyl alcohol and epichlorohydrin; a reaction product of polyvinyl phenol and epichlorohydrin; a reaction product of polyacrylamide and epichlorohydrin; a reaction product of epichlorohydrin and cellulose; and a reaction product of epichlorohydrin and a cellulose derivative. The same polyamide-reversed osmosis membrane according to claim 6, wherein the polyfunctional epoxy compound is cross-linked by self-polymerization. The composite polyamide reverse osmosis membrane according to claim 1, wherein the polyfunctional epoxy compound is cross-linked with the aid of a cross-linking compound. 10. A composite polyamide reverse osmosis membrane according to claim 9, wherein the cross-linking compound comprises at least two epoxy-reactive groups selected from the group consisting of hydroxy groups; amino groups; carboxyl groups; carboxylic anhydride groups; amide groups; carbonyl groups; and sulfur hydryl (thiol) groups. 11. A composite polyamide reverse osmosis membrane according to claim 10, wherein the cross-linking compound is at least one compound selected from the group consisting of ethylene glycol; propylene glycol; 1,3-propanediol; 1,3-butanediol; 1,4-butanediol; 1,5-pentanediol; 1,2-pentanediol; 2,4-pentanediol; 1,6-hexanediol; 1,2-hexanediol; 1,5-hexanediol; 2,5-hexanediol; 2-ethyl-1,3,4-hexanediol; 1,7-heptanediol; 1,2-octanediol; 1,8-octanediol; 1.9-1020950 # 26 nonanediol; 1,10-decanediol; 1,2-decanediol; 1,12-dodecanediol; 1,2-dodecanediol; glycerol; trimethylolpropane; 1,1,1-tris (hydroxymethyl) ethane; 1,1,1-tris (hydroxyphenyl) ethane; tris (hydroxymethyl) -aminomethane; tris (hydroxymethyl) nitromethane; 1,3,5-tris (2- hydroxyethyl) cyanouric acid; pentaerythritol; sorbitol; glucose, fructose; maltose; mannose; glucosamine; mannosamine; a polysaccharide; neopentyl glycol; dibromo neopentyl glycol; hydroquinone; resorcinol; bisphenol A; hydrogenated bisphenol A; isocyanic urea acid; phloroglucinol; methylenebisaniline; novolak resin; poly-vinyl alcohol; polyvinyl phenol; polyacrylamide; cellulose; ethyl cellulose; methyl cellulose; hydroxypropylcellulose; hydroxyethyl cellulose; polyethylene glycol with the repeating ethylene glycol unit (CH 2 CH 2 O) n wherein n is in the range of 2 to 400; and polypropylene glycol with the repeating ethylene glycol unit 15 ((CH 3) CH 2 CH 2 O) n wherein n is in the range of 2 to 100. 12. A composite polyamide reverse osmosis membrane according to claim 10, wherein the crosslinking compound is at least one compound selected from the group consisting of alkanediamines and their alkyl or aryl derivatives on nitrogen atoms and skeletal carbon atoms of the types shown below; H 2 N (CH 2) n NH 2 wherein n = 2-12; H 2 N (CH 2 CH 2 O) • CH 2 CH 2 NH 2 where n = 1-400; R 1 R 2 N (CH 2) n NR 3 R 8 wherein n = 2-12 and R 1, R 2, R 3 and R * are the same or different and are selected from the group consisting of hydrogen, methyl, ethyl, propyl, butyl, cyclohexyl and phenyl; R 5 R 5 II H 2 N (CH 2) n NH 2 and R 1 R 2 N (CH 2) n NR a R 4 wherein n = 1-12 and R 1, R 2 / R 3, R 4 and R 5 are the same or different and are selected from the group consisting of methyl, ethyl, propyl , butyl, cyclohexyl, hydroxyl and phenyl; alicyclic diamines selected from the group consisting of diaminocyclohexane; 1,3-cyclohexane bis (methylamine); 4,4'-trimethylenedipiperidine; piperazine; 1,4-dimethyl piperazine; 1,4-35 diazabicyclo [2.2.2] octane; 1,8-diazabi-cyclo [5.4.0] undec-7-ene; 1,5-diazabicyclo [4.3.0] non-5-ene; and aromatic diamines selected from the group consisting of meta-phenylenediamine; meta-xylylenediamine; and bis (4-amino-phenyl) sulfone. 'f020950 · - 27 - The composite polyamide reverse osmosis membrane according to claim 10, wherein the crosslinking compound is at least one compound selected from the group consisting of N, N'-bis (2-aminoethyl) -1,3-propanediamine; diethylene triamine; triethylene tetramine; tris (2-aminoethyl) amine; Ν, Ν, Ν ', N', N "-penta-methyl-diethylenetriamine; triaminobenzene; 1,1,3,3-tetramethyl-guanidine, polyethyleneimine; chitosan; poly (allylamine); and polyvinyl-pyridine. The composite polyamide reverse osmosis membrane according to claim 10, wherein the cross-linking compound is at least one compound selected from the group consisting of tartaric acid; gluconic acid; glucuronic acid; 3,5-dihydroxybenzoic acid; 2,5-dihydroxy-benzene sulfonic acid potassium salt; and 2,5-dihydroxy-1,4-benzenedisulfonic acid dipotassium salt; 3,5-diaminobenzoic acid; 2-aminoethanesulfonic acid (taurine); 2 - {[tris) hydroxymethyl) methyl] amino} -1-ethanesulfonic acid; 3 - {[tris (hydroxymethyl) methyl] amino} -1-propane sulfonic acid; 2-hydroxy-3 - {[tris (hydroxymethyl) methyl] amino} -1-propane sulfonic acid; fl-hydroxy-4- (2-hydroxyethyl) -1-piperazine propanesulfonic acid; β, β'-dihydroxy-1,4-piperazine bis (propane sulfonic acid); and 2,5-diaminoben-20 sea sulfonic acid. The composite polyamide reverse osmosis membrane according to 'claim 1, wherein the polyfunctional epoxy compound is at least one compound selected from the group consisting of ethylene glycol diglycidyl ether; propylene glycol diglycidyl ether; 1,3-propanediol diglycidyl ether; 1,3-butanediol diglycidyl ether; 1,4-butanediol diglycidyl ether; 1,5-pentanediol diglycidyl ether; 1,2-petanediol diglycidyl ether; 2,4-pentanediol diglycidyl ether; 2,5-hexanediol diglycidyl ether; 2-ethyl-1,3-hexanediol diglycidyl ether; 1,7-heptanediol diglycidyl ether; 1,2-octanediol diglycidyl ether; 1, 8-30 octanediol diglycidyl ether; 1,9-nonanediol diglycidyl ether; 1,10-decanediol diglycidyl ether; 1,2-decanediol diglycidyl ether; 1,12-dodecanediol diglycidyl ether; 1,2-dodecanediol diglycidyl ether; glycerol diglycidyl ether; trimethylolpropane diglycidyl ether; 1,1,1-tris (hydroxymethyl) ethanediglycidyl ether; pentaerythritol diglycidyl ether; sorbitol diglycidyl ether; neopentyl glycol diglycidyl ether; dibromo neopentyl glycol diglycidyl ether; hydroquinone diglycidyl ether; resorcinol diglycidyl ether; bisphenol A diglycidyl ether; hydrogenated bisphenol A diglycidyl ether; polyethylene glycol diglycidyl ether with the repeating ethylene glycol unit (CH 2 CH 2 O) n where n 40 is an integer in the range of 2 to 400; and 10209 50 * - 28 - polypropylene glycol diglycidyl ether with the repeating polypropylene glycol unit ((CH 3) CH 2 CH 2 O) n where n is an integer in the range of 2 to 100. The composite polyamide reverse osmosis membrane according to claim 1, wherein the polyfunctional epoxy compound is cross-linked using a cross-linking compound, wherein the cross-linking compound has at least three epoxy-reactive groups. 17. The composite polyamide reverse osmosis membrane according to claim 16, wherein the at least three epoxy-reactive groups of the cross-linking compound are selected from the group consisting of hydroxy groups; amino groups; carboxyl groups; carboxylic acid anhydride groups; amide groups, carbonyl groups; and sulfur hydryl (thiol) groups. The composite polyamide reverse osmosis membrane according to claim 16, wherein the crosslinking compound is at least one compound selected from the group consisting of N, N'-bis (2-aminoethyl) 1,3-propanediamine, diethylene triamine, triethylene triamine; tris (2-aminoethyl) amine; Ν, Ν, Ν ', Ν', N "-pentamethyldiethylenediamine; triaminobenzene; 1,1,3,3-tetramethylguanidine; polyethyleneimine; chitosan; poly (allylamine); and polyvinylpyridine; tartaric acid; gluconic acid; glucuronic acid; 3,5-dihydroxybenzoic acid; 2,5-dihydroxybenzene sulfonic acid potassium salt; and 2,5-dihydroxy-1,4-benzene disulfonic acid dipotassium salt; glycerol; trimethylolpropane; 1,1,1-tris (hydroxymethyl) ethane; 1/1 / 1-tris (hydroxyphenyl) ethane; tris (hydroxymethyl) aminomethane; tris (hydroxymethyl) nitromethane; 1,3,5-tris (2-hydroxyethyl) cyanouric acid; pentaerythritol; sorbitol; glucose; fructose; maltose; mannose; glucosamine; manno samine; a polysaccharide; isocyanuric acid; floroglucinol; methylenebisaniline; novolak resin; polyvinyl alcohol; polyvinyl phenol; polyacrylamide; and cellulose and its derivatives. The composite polyamide reverse osmosis membrane according to claim 1, wherein the polyfunctional epoxy compound is cross-linked using a cross-linking compound, wherein the cross-linking compound is a diamino compound with two primary amino groups, two secondary amino groups or a primary amino group and a secondary amino group. A method of manufacturing a coated composite polyamide reverse osmosis membrane, the method 40 comprising the steps of: 10209 50 * - 29 - (a) coating a porous support with an aqueous solution, wherein the aqueous solution is a polyfunctional amine to form a fluid layer on the porous support; (B) contacting the liquid layer with an organic solvent solution, wherein the organic solvent solution comprises an amine-reactive reagent selected from the group consisting of a polyfunctional acyl halide, a polyfunctional sulfonyl halide and a polyfunctional isocyanate so as to reach its interface condensing the amine-reactive reagent with the polyfunctional amine, thereby forming a cross-linked, interfacial polyamide layer on the porous support; and (c) drying the product of step (b) to form a composite polyamide reverse osmosis membrane; (d) subsequently forming a hydrophilic coating on the cross-linked interface polyamide layer of the composite polyamide reverse osmosis membrane by: (i) applying to the cross-linked interface polyamide film an amount of a polyfunctional epoxy compound, wherein the polyfunctional epoxy compound is at least comprises two epoxy groups; and (ii7 subsequently cross-linking the polyfunctional epoxy compound in such a way that a water-insoluble polymer is obtained. The method of claim 20, further comprising, between steps (c) and (d), the steps of rinsing the product of step (c) in a basic aqueous solution, and then rinsing the thus rinsed product with deionized water. The method of claim 20, wherein the step of applying the polyfunctional epoxy compound to the cross-linked interface polyamide film comprises forming the polyfunctional epoxy compound, and then treating the cross-linked interface polyamide film with the polyfunctional epoxy compound. The method of claim 20, wherein the polyfunctional epoxy compound is applied to the cross-linked interface polyamide film as a part of a coating solution comprising: (i) a solvent comprising at least one of water and an alcohol; and (i) the polyfunctional epoxy compound in an amount in the range of about 0.0001% by weight to 20% by weight of the coating solution. The method of claim 23, wherein the polyfunctional epoxy compound is present in the coating solution in an amount in the range of about 0.00001% to 5% by weight of the coating solution. 25. The method of claim 20, wherein the step of applying the polyfunctional epoxy compound to the crosslinked interface polyamide film comprises treating the crosslinked interface polyamide film with reagents to prepare the polyfunctional epoxy compound, and then forming the polyfunctional epoxy compound epoxy compound in situ at the cross-linked interface polyamide film. 26. The method of claim 20, wherein the cross-linking of the polyfunctional epoxy compound is catalyzed by a catalyst selected from the group consisting of a base, an acid, and heat. 27. The method of claim 26, wherein the base is at least one compound selected from the group consisting of an alkoxide salt; a hydroxide salt; a carbonate salt; a phosphate salt; a phenoxide salt; a borate salt; a carboxylate; ammonia; a primary amine; a secondary amine; and a tertiary amine. 28. The method of claim 26, wherein the acid is at least one compound selected from the group consisting of sulfuric acid; hydrochloric acid; nitric acid; an aromatic sulfonic acid; an aliphatic sulfonic acid; a cycloaliphatic sulfonic acid; a carboxylic acid; a fluorinated carboxylic acid; phenol and its derivatives; boric acid; tetrafluoroboric acid; aluminum trihalide; an aluminum trialkoxide; a boron trihalide; zinc trafluoroborate; a tin tetrahalide; a quaternary ammonium salt; and an acid salt of ammonia or a primary, secondary or tertiary amine. The method of claim 26, wherein the heat comprises heating at about 10 ° C to 20 ° C for a period of about 1 second to 7 days. The method of claim 20, wherein the cross-linking of the polyfunctional epoxy compound is catalyzed by heating at about 10 ° C to 150 ° C for a period of about 1 second to 2 days in the presence of one of a base and an acid . 1020950 * - 31 - A microporous membrane comprising: (a) a microporous support; and (b) a hydrophilic coating on the microporous support, the hydrophilic coating being made by: (i) applying to the microporous support an amount of a polyfunctional epoxy compound, wherein the polyfunctional epoxy compound comprises at least two epoxy groups; and (ii) then cross-linking the polyfunctional epoxy compound in such a way that a water-insoluble polymer is obtained. The microporous support of claim 31, wherein the microporous support is a microfiltration membrane. The microporous support of claim 31, wherein the microporous support is an ultrafiltration membrane. A method of manufacturing a coated microporous membrane, the method comprising the steps of: (a) providing a microporous support; and (b) subsequently forming a hydrophilic coating on the microporous support by: (i) applying to the microporous support an amount of a polyfunctional epoxy compound, wherein the polyfunctional epoxy compound comprises at least two epoxy groups; and (ii) then cross-linking the polyfunctional epoxy compound in such a way that a water-insoluble polymer is obtained. 1020950 «