GB2139113A - Reverse osmosis membrane and method for the preparation thereof - Google Patents
Reverse osmosis membrane and method for the preparation thereof Download PDFInfo
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- GB2139113A GB2139113A GB08404855A GB8404855A GB2139113A GB 2139113 A GB2139113 A GB 2139113A GB 08404855 A GB08404855 A GB 08404855A GB 8404855 A GB8404855 A GB 8404855A GB 2139113 A GB2139113 A GB 2139113A
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- Prior art keywords
- membrane
- semipermeable
- prepolymer
- amine
- solution
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- 239000012528 membrane Substances 0.000 title claims abstract description 63
- 238000001223 reverse osmosis Methods 0.000 title claims abstract description 20
- 238000000034 method Methods 0.000 title claims description 20
- 238000002360 preparation method Methods 0.000 title claims description 5
- 150000001412 amines Chemical class 0.000 claims abstract description 31
- 230000004907 flux Effects 0.000 claims abstract description 15
- -1 aromatic anhydride Chemical class 0.000 claims abstract description 14
- 150000003839 salts Chemical class 0.000 claims abstract description 14
- 229920002492 poly(sulfone) Polymers 0.000 claims abstract description 12
- 238000006482 condensation reaction Methods 0.000 claims abstract description 11
- 239000004952 Polyamide Substances 0.000 claims abstract description 9
- 150000004984 aromatic diamines Chemical class 0.000 claims abstract description 9
- 229920002647 polyamide Polymers 0.000 claims abstract description 9
- 150000001266 acyl halides Chemical class 0.000 claims abstract description 8
- UWCPYKQBIPYOLX-UHFFFAOYSA-N benzene-1,3,5-tricarbonyl chloride Chemical compound ClC(=O)C1=CC(C(Cl)=O)=CC(C(Cl)=O)=C1 UWCPYKQBIPYOLX-UHFFFAOYSA-N 0.000 claims abstract description 8
- 238000011065 in-situ storage Methods 0.000 claims abstract description 4
- 239000000243 solution Substances 0.000 claims description 35
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 24
- 150000004820 halides Chemical class 0.000 claims description 20
- 239000002131 composite material Substances 0.000 claims description 14
- 239000000758 substrate Substances 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 7
- 150000001408 amides Chemical class 0.000 claims description 5
- 125000003118 aryl group Chemical group 0.000 claims description 5
- 239000012454 non-polar solvent Substances 0.000 claims description 5
- 229910052736 halogen Inorganic materials 0.000 claims description 4
- 125000005843 halogen group Chemical group 0.000 claims description 4
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 3
- 150000008064 anhydrides Chemical class 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 238000001723 curing Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 235000019333 sodium laurylsulphate Nutrition 0.000 claims description 3
- 125000003277 amino group Chemical group 0.000 claims description 2
- 239000002244 precipitate Substances 0.000 claims description 2
- 125000002837 carbocyclic group Chemical group 0.000 claims 2
- 150000008280 chlorinated hydrocarbons Chemical class 0.000 claims 2
- 239000011248 coating agent Substances 0.000 claims 2
- 238000000576 coating method Methods 0.000 claims 2
- 229920006395 saturated elastomer Polymers 0.000 claims 2
- 150000004982 aromatic amines Chemical class 0.000 claims 1
- 239000007795 chemical reaction product Substances 0.000 claims 1
- 238000001035 drying Methods 0.000 claims 1
- 238000001914 filtration Methods 0.000 claims 1
- 239000010408 film Substances 0.000 abstract description 11
- 238000006243 chemical reaction Methods 0.000 abstract description 9
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 abstract description 8
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 abstract description 6
- 229910052801 chlorine Inorganic materials 0.000 abstract description 6
- 239000000460 chlorine Substances 0.000 abstract description 6
- 239000010409 thin film Substances 0.000 abstract description 2
- NJMOHBDCGXJLNJ-UHFFFAOYSA-N trimellitic anhydride chloride Chemical compound ClC(=O)C1=CC=C2C(=O)OC(=O)C2=C1 NJMOHBDCGXJLNJ-UHFFFAOYSA-N 0.000 abstract 1
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 20
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 8
- 239000002904 solvent Substances 0.000 description 7
- 238000007792 addition Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 150000001263 acyl chlorides Chemical class 0.000 description 3
- 238000004132 cross linking Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 150000003141 primary amines Chemical group 0.000 description 3
- TWTCFDQXNADDLQ-NTISSMGPSA-N (2s)-2-amino-n-(4-methyl-2-oxochromen-7-yl)-3-phenylpropanamide;2,2,2-trifluoroacetic acid Chemical compound OC(=O)C(F)(F)F.C([C@H](N)C(=O)NC1=CC=2OC(=O)C=C(C=2C=C1)C)C1=CC=CC=C1 TWTCFDQXNADDLQ-NTISSMGPSA-N 0.000 description 2
- 238000012695 Interfacial polymerization Methods 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000010406 interfacial reaction Methods 0.000 description 2
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical class CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 2
- 229920000728 polyester Polymers 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 125000001424 substituent group Chemical group 0.000 description 2
- 241000894006 Bacteria Species 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920001747 Cellulose diacetate Polymers 0.000 description 1
- 239000004801 Chlorinated PVC Substances 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical class CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 125000000777 acyl halide group Chemical group 0.000 description 1
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 239000004760 aramid Substances 0.000 description 1
- 229920003235 aromatic polyamide Polymers 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- FDQSRULYDNDXQB-UHFFFAOYSA-N benzene-1,3-dicarbonyl chloride Chemical compound ClC(=O)C1=CC=CC(C(Cl)=O)=C1 FDQSRULYDNDXQB-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 235000012206 bottled water Nutrition 0.000 description 1
- 125000002843 carboxylic acid group Chemical group 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 238000002144 chemical decomposition reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229920000457 chlorinated polyvinyl chloride Polymers 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 239000003431 cross linking reagent Substances 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 239000003651 drinking water Substances 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 238000013007 heat curing Methods 0.000 description 1
- 150000004678 hydrides Chemical class 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 239000012429 reaction media Substances 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
- B01D69/1251—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction by interfacial polymerisation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/56—Polyamides, e.g. polyester-amides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
Abstract
A reverse osmosis membrane having a high flux with superior chlorine resistance and low salt passage is obtained by interfacially condensing polyamide prepolymer with monomeric amine reactive polyfunctional acyl halide, the reaction taking place, in situ, on a porous support such as a polysulfone film. The polyamide prepolymer is prepared through the condensation reaction of an aromatic diamine and an aromatic anhydride. Preferably the polyamide prepolymer, prepared from metaphenylene diamine and trimellitic anhydride acid chloride, is reacted with trimesoyl chloride to form a thin film membrane.
Description
SPECIFICATION
Reverse osmosis membrane and method for the preparation thereof
The subject invention relates to reverse osmosis apparatus and more particularly to an improved polyamide membrane module for use in such reverse osmosis apparatus and a method for preparing and using these membrane modules.
The removal of solutes from a solution by the separation of those solutes from the carrier solvent through a system utilizing a process known as reverse osmosis is well known in the art. Such a system typically has a barrier membrane separating the solvent from the solution. The solution, usually aqueous, is introduced into one compartment of the system through a pump at pressures up to 1000 psig, the pressure being dependent chiefly on the species and concentration of the solutes. Both purified solvent and concentrated solution are continuously withdrawn from the system.
The effectiveness and efficiency of reverse osmosis apparatus depends principally on the performance of the membrane. In applications involving the desalination of seawater or brackish water sources, a reverse osmosis membrane must have high salt rejection characteristics, be capable of a high flux rate, and be resistentto deterioration by hydrolysis and by exposure to high pressure, temperature and dissolved chlorine.
An efficient reverse osmosis process generally requires a salt rejection capability of greater than 95%.
Greater than 99.5% salt rejection characteristics is preferred. With such a capability, seawater of a typical 35,000 ppm salt content can, in a single pass through the system, be reduced to potable water of 175 ppm, a concentration much less than many untreated tap waters.
The flux rate or fluid flow rate through the membrane is important to the economics of the operation. High membrane flux rates permit the system to be built with less membrane and other associated equipment.
Chlorine and other oxidizing agents are often present in the solutions fed to a reverse osmosis system being utilized for fighting bacteria growth and the like. The presence of chlorine in the feed can greatly affect the life of the membrane through a mechanism of degradation that has been postulated as a reaction with primary amidic hydrogens. Such chemical degradation results in a relatively short useful life of the membrane, drastically reducing the ability of a membrane to reject salt over a relatively short period of time.
The first practical membranes utilized in reverse-osmosis procedures were formed of cellulose diacetate, being characterized by a very thin, dense surface layer adjacent to a much thicker supporting layer. Further development in this area introduced the ultrathin film secured to a separate thicker porous support. While initially prepared separately, the film or membrane can now be formed in situ on the support layer by a technique known as interfacial condensation. The history of this art as taught in the scientific literature and patents may be found in United States Patent No. 4,277,344. In addition, the above-identified patent provides specific examples of this technique.
Summary of the Invention
Therefore, an object of the subject invention is an improved semi-permeable membrane for use in reverse-osmosis systems.
Another object of the subject invention is a semi-permeable membrane and method for the preparation of a semi-permeable membrane which has excellent salt-rejection characteristics, variably controlled flux rates, resistance to biological and hydrolytic degradation, reduced pH sensitivity, and improved resistance to deterioration in the presence of chlorine-containing feed water.
These and other objects are provided by the subject invention wherein an excellent reverse osmosis membrane can be obtained by condensing water soluble aromatic polyamide prepolymer with an essentially monomeric, aromatic, amine reactive polyfunctional acyl halide. The prepolymer may be prepared through the condensation reaction of an aromatic diamine and an aromatic anhydride, preferably the reaction between metaphenylene diamine and trimelletic anhydride acid chloride. The reverse osmosis membrane of the subject invention comprises a microporous substrate, preferably of polysulfone supported by polyester non-woven fabric, and an ultrathin film or membrane having semi-permeable properties deposited or secured to one side of the microporous substrate.The procedure for preparing the above-described membrane includes the steps of (a) treating an appropriate microporous substrate with an aqueous solution of the previously prepared polyamide prepolymer; (b) contacting the prepolymer coated substrate with a solution of an acyl halide in a nonpolar solvent where an interfacial condensation reaction occurs; and (c) heat curing the composite membrane.
Detailed Description of the Invention
As will be described in greater detail below, composite reverse osmosis membranes characterized by controlled flux, high rejection of solutes, and good resistance to attack by chlorine can be prepared by the interfacial polymerization reaction of a layer or film of an aqueous solution of the amine prepolymer having terminal primary amines on a porous support with, for example, a triacyl halide in a nonpolar solvent, particularly as exemplified by a solution of trimesoyl chloride, i.e., 1,3,5-benzenetricarboxylic acid chloride in heptane. The amine prepolymer which may be used to form the membrane of the subject invention may be prepared as set forth below.
In the conduct of this interfacial reaction, the acyl halide groups react with the primary amine groups of the prepolymerto produce amide linkages. Reaction is essentially instantaneous at the interface of acyl chlorides with amines. The three-pronged functionality of the triacyl halides is theorized to lead to the generation of a highly crosslinked, three-dimensional polymeric network in the membrane. The reverse osmosis membrane material is thus a polymer approaching a large molecular weight.While the prior art has recognized that diacyl halides do not necessarily improve the performance of the resulting membrane when used in conjunction with the triacyl halides, they may be of use in adjusting certain physical properties of the membrane such as specific ion rejection, permeate flux, and the like. 1 to 1 through 10 to 1 ratiosoftriacyl halides to diacyl halides appear most effective.
As a direct result of the high degree of crosslinking, the reverse osmosis membrane of the subject invention is generally insoluble in virtually any solvent that does not first seriously degrade its molecular structure. However, not all of the acyl halide functional groups become bound into amide linkages. A substantial proportion of the acyl halide functional groups are hydrolyzed by the water present in the amine reagent as solvent, generating carboxylic acid groups or carboxylate salts. These carboxyl groups have been discovered to exert surprising effects on the performance of the interfacial membrane, in that they effect flux and profoundly affect the membrane's rejection of aqueous dissolved solutes.
The amines prepolymer can be formed by the condensation reaction of an aromatic diamine and an aromatic anhydride. Examples of aromatic diamines suitable for use in the preparation of the amine prepolymer are:
where R = H, CH3, Halogen; and
where R1 =
Examples of the aromatic anydride which may be used to prepare the amine prepolymer are:
where X = halogen group
where R2 =
In addition, an acyl halide, such as trimesoyl chloride, or isophthaloyl chloride may be added to the reaction mixture of amine and an hydride to vary the properties of the resulting reverse osmosis membrane.
The addition of such an acyl chloride when preparing the prepolymer would tend to add more crosslinking, which can affect the processibility of the membrane of the subject invention. Such addition of a strengthening crosslinking agent may also have the effect of reducing flux, though any noticeable consequence would depend greatly on the amount and identity of the acyl chloride added. As a result, generalizations concerning the effects of such additions cannot be reliably made.
In preparing the amine prepolymer, the aromatic diamine as set forth above is dissolved in a solution of methylene chloride and dimethyl formamide. A solution of the aromatic anhydride in methylene chloride is filtered to remove any hydrolyzed anhydride, and added to the amine solution with rapid stirring. The resulting solution is filtered, and the precipitate dried.
When meta-phenylenediamine and trimelletic anhydride acid chloride are the respective reactants, the prepolymerthus prepared has an average molecular weight in excess of approximately 400 and is primary amine terminated. The molecular formula of such an amine prepolymer can be represented as:
NH2 - [ Ar-NH-CO-Ar-CO-NH-Ar ] -NH2 I n
COOH where Ar represents any carbocyclic monocyclic aromatic nucleus free of any acyl halide reactive group other than terminal amine groups and n represents a chain length of from 1 - 10. It should be recognized that varying concentrations of prepolymers of different chain lengths, may be prepared dependent chiefly on the relative concentration of the reactants and crosslinking substituents.
After forming the amine prepolymer, the thin film composite membranes of the subject invention may be formed by a series of steps comprising (1 ) application of an aqueous amine prepolymer solution to the porous support; (2) reaction with the acid halide, by contacting the prepolymer containing support with the acid halide solution; and (3) curing by heating in an oven at approximately 110 - 50 C, preferably 1 30 C.
The porous support may be any of the type conventionally used in reverse osmosis processes. The preferred supports, however, are those prepared from organic polymeric materials such as polysulfone, chlorinated polyvinyl chloride, polyvinyl butyral, polystyrene, cellulose esters, etc. Polysulfone film has been found to be a particularly effective support material for the membranes of the invention. Such polysulfone supports can be prepared by depositing a layer of polysulfone (Union Carbide P-3500) solution on a polyester unwoven fabric support material.
To the aqueous amine prepolymer may be added an agent for lowering its surface tension, i.e., increasing the wetting capability of the aqueous amine prepolymer solution. Detergents, such as the salts of alkyl hydrogen sulfates having a carbon chain length of C12 to C18 are particularly desirable. Specifically, sodium lauryl sulfate, n-C11H23CH2OSO NA+, exemplifies that which may be used.
The polyacyl halide of choice is trimesoyl chloride, primarily because of its ability to crosslink and form insoluble films. However, other polyacyl halides, such as that presented by the formula: Ar(COX)a wherein
Ar is a mono- or polynuclear aromatic nucleus free of amine reactive substituents other than (COX); X is hologen; and a#2. The polyacyl halide should be at least 0.01 weight-% soluble in liquid C1-C12 alkane or liquid halogenated lower alkane solvents. The 0.01 weight-per cent represents the lower limit of solubility of the polyacyl halide in the nonpolar solvent which can be used in the interfacial polymerization reaction; concomitantly, ease of production on a commercial scale dictates a level of solubility of at least 1 weight-per cent or more of the polyacyl halide in a suitable nonpolar solvent.Actually, most aromatic polyacyl halides are readily soluble in liquid aliphatic solvents such as the pentanes, hexanes, heptanes, octanes, etc. which are substantially inert toward the preferred porous support materials such as the polysulfones.
After formation of the ultrathin membrane by interfacial condensation reaction of the amine prepolymer and polyacyl halide, the composite is generally cured at 1 30 C for 5 minutes. Other temperatures and times may be used to achieve the desired cure.
In the Examples which follow, all parts and percentages aie by weight unless otherwise indicated.
Example 1
To 500 ml of Dichloromethane is added 25.0 g (0.24 moles) of metaphenylene diamine (MPD) and 13.2 g (0.16 moles) of Dimethylformamide (DMF). To another 200 ml of Dichloromethane, 16.0 g (0.08 moles) of trimelletic anhydride acid chloride (TMAAC) is added, and after this in solution, it is filtered to remove hydrolyzed TMAAC.
With rapid stirring of the MPD/DMF solution prepared above, slowly (15 - 20 ml/min) add the filtered
TMAAC solution. This reaction is carried out at room temperature, but a slight increase in temperature will be observed, and should not boil the CH2Cl2 if slow addition of the TMAAC is observed.
After the addition is complete, immediately filter the reaction solution. Wash the precipitated prepolymer with 500 ml of CH2Cl2, and collect the precipitated again with suction. Dry the prepolymer at 30 C under vacuum for 24 hours.
A polysulfone support film was prepared from a 15% solution of Union Carbide's P-3500 polysulfone in
DMF. Sixteen grams of the amine prepolymerwas dissolved in 0.5% NaOH solution with 0.1% sodium lauryl sulfate added to form a 2% amine prepolymer solution. The polysulfone support film was coated by immersion in the amine prepolymer solution. Excess amine prepolymer solution was removed by draining and the wet coated polysulfone film was immediately covered with a 0.5% heptane solution of
Trimesolchloride (TMC). Contact time for the interfacial reaction was 10 seconds. The resulting composite membrane was further cured by heating at 1 300C for 5 minutes. The membrane was placed in a cell designed for characterizing RO membrane films and at 200 PSI.The membrane rejected 99.1% of the dissolved salt from a 2000 PPM sodium chloride solution, and at a flux of 5 gallons per square foot per day (GFD).
Example 2
A composite membrane was made according to the procedure of Example 1, with the exception that no final curing step was employed. No rejection of salt was observed in the subsequent test under the conditions of Example 1.
Example 3
The procedure of Example 1 was followed except the ratio of MPD to TMAAC was increased to 4 to 1 and cured at 11 20C for 5 minutes. The observed flux was 5.6 GFD with a salt rejection of 98.5%.
Example 4
The procedure of Example 1 was followed except the ratio of MPD to TMAAC in the prepolymer was increased to 5 to 1 and the membrane was cured at 110 C for 5 minutes. The observed flux was 5.6 GFD with a 98.8% salt rejection.
Example 5
The procedure of Example 1 was followed, however, to the triacyl chloride was added sufficient diacyl chloride in the form of isophathoyl chloride to achieve a ratio of (a) 7.5 to 1 and (b) 4.2 to 1. The observed flux was (a) 3.7 GFD and (b) 10.1 GFD; the salt rejection for each was (a) 98.5% and (b) 85%.
Example 6
The procedure of Example was followed, however in (c) the relative volumetric amount of DMF and CH2Cl2 was changed to a volumetric ratio of 1 DMF/10 CH2Cl2 in the prepolymer reaction medium as opposed to .22/10 in (a) and (b). In addition, 1 mole of Trimesoylchloride (TMC) was added in preparing the prepolymer for every 9 moles TMAAC in (c).The prepolymer treated porous support was immersed in a solution of 0.5%
TMC in heptane to form the membranes for which the following values were observed:
(a) (b) (c)
flux 4GFD 8G FD 1 1.2 GFD salt rejection 96% 98.5% 98.6%
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (17)
1. A semipermeable composite membrane comprising a porous substrate and a polyamide coating on said substrate, said polyamide coating being formed by the interfacial condensation reaction of an amide prepolymer and a monomeric amine reactive polyacyl halide, said amide prepolymer being formed by the condensation reaction of an aromatic diamine and an aromatic anhydride.
2. The semipermeable composite membrane of Claim 1 wherein said interfacial condensation reaction occurs in situ on said porous substrate.
3. The semipermeable membrane of Claim 1 wherein said porous substrate comprises a polysulfone material.
4. The semipermeable membrane of Claim 1 wherein said polyacyl halide comprises a triacyl halide.
5. The semipermeable membrane of Claim 4 wherein said triacyl halide comprises trimesoylchloride.
6. The semipermeable membrane of Claim 1 wherein said aromatic diamine is selected from the group of:
where X = halogen, H, CH3, and
7. The semipermeable membrane of Claim 1 wherein said aromatic anhydride is selected from the group of:
where X = halogen
and,
where R2 =
8. The semipermeable membrane of Claim 1 further including sodium lauryl sulfate added to the amine prepolymer.
9. The semipermeable membrane of Claim 1 wherein said amine prepolymer comprises:
where n = 1 - 10
10. A process for the preparation of a semipermeable composite membrane comprising the steps of:
a) immersing a porous substrate in a basic aqueous solution of an aromatic amine prepolymerformed by the condensation reaction of an aromatic diamine and an aromatic anhydridge;
b) removing the excess of said amine prepolymer from said substrate, leaving said substrate saturated with said amine prepolymer solution;
c) contacting said saturated substrate with a solution of a trizcyl halide in a nonpolar solvent;
d) draining said substrate of excess solution; and
e) curing said substrate by heating at about 100 - 1500C for about 1 - 10 minutes, thereby forming said semipermeable composite membrane suitable for use in a reverse osmosis application with a flux of at least 5 GFD at 25 C and a salt rejection capability of at least 90%.
11. The process of Claim 10 further including the steps of forming said amine prepolymer by:
a) dissolving an aromatic diamine in a solution of chlorinated hydrocarbon and dimethylformamide to form an amine solution;
b) dissolving an aromatic anhydride in chlorinated hydrocarbon to form an anhydride solution;
c) adding said anhydride solution to said amine solution;
d) filtering out prepolymer precipitate; and
e) drying said prepolymer.
12. A semipermeable composite membrane prepared according to Claim 10.
13. A semipermeable composite membrane comprising a porous support component and a semipermeable polyamide component; said polyamide component being essentially the interfacial condensation reaction product of:
where Ar represents a carbocyclic, monocyclic aromatic nucleus free of any acyl halide reactive group other than the terminal amine groups and n represents a chain length from 1 - 10;
b) Ar'(COX)3 wherein Ar' represents a carbocyclic, monocyclic aromatic nucleus free of any amide forming groups other than the COX substituent, and X represents a halogen.
14. A semipermeable membrane according to Claim 13 where said Ar'(COX)3 is trimesoyl chloride.
15. The semipermeable membrane of Claim 13 wherein the interfacial condensation reaction occurs in situ on said porous support.
16. A process for forming a semipermeable composite membrane substantially as described herein with reference to the specific examples.
17. A semipermeable composite membrane when formed by any any process according to Claim 16.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US47672783A | 1983-03-18 | 1983-03-18 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8404855D0 GB8404855D0 (en) | 1984-03-28 |
| GB2139113A true GB2139113A (en) | 1984-11-07 |
| GB2139113B GB2139113B (en) | 1987-02-18 |
Family
ID=23893004
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08404855A Expired GB2139113B (en) | 1983-03-18 | 1984-02-24 | Reverse osmosis membrane and method for the preparation thereof |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1220990A (en) |
| GB (1) | GB2139113B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1990002602A1 (en) * | 1988-09-14 | 1990-03-22 | Allied-Signal Inc. | Chlorine-resistant semipermeable membranes |
| EP0503596A2 (en) * | 1991-03-12 | 1992-09-16 | Toray Industries, Inc. | Process for producing composite semipermeable membrane |
| ES2050606A1 (en) * | 1992-09-02 | 1994-05-16 | Toray Industries | Procedure for the production of a semipermeable membrane |
| WO2012102944A1 (en) * | 2011-01-24 | 2012-08-02 | Dow Global Technologies Llc | Composite polyamide membrane |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2027614A (en) * | 1978-05-22 | 1980-02-27 | Teijin Ltd | Semipermeable composite membrane and process for preparation thereof |
| EP0015149A1 (en) * | 1979-02-22 | 1980-09-03 | FilmTec Corporation | Interfacially synthesized reverse osmosis membrane, process for the preparation thereof and its use in a process for removing solute from solute-containing water |
-
1983
- 1983-11-18 CA CA000441485A patent/CA1220990A/en not_active Expired
-
1984
- 1984-02-24 GB GB08404855A patent/GB2139113B/en not_active Expired
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2027614A (en) * | 1978-05-22 | 1980-02-27 | Teijin Ltd | Semipermeable composite membrane and process for preparation thereof |
| EP0015149A1 (en) * | 1979-02-22 | 1980-09-03 | FilmTec Corporation | Interfacially synthesized reverse osmosis membrane, process for the preparation thereof and its use in a process for removing solute from solute-containing water |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1990002602A1 (en) * | 1988-09-14 | 1990-03-22 | Allied-Signal Inc. | Chlorine-resistant semipermeable membranes |
| EP0503596A2 (en) * | 1991-03-12 | 1992-09-16 | Toray Industries, Inc. | Process for producing composite semipermeable membrane |
| EP0503596A3 (en) * | 1991-03-12 | 1993-03-10 | Toray Industries, Inc. | Process for producing composite semipermeable membrane |
| US5324538A (en) * | 1991-03-12 | 1994-06-28 | Toray Industries, Inc. | Process for producing composite semipermeable membrane employing a polyfunctional amine solution and high flash point - solvent |
| ES2050606A1 (en) * | 1992-09-02 | 1994-05-16 | Toray Industries | Procedure for the production of a semipermeable membrane |
| WO2012102944A1 (en) * | 2011-01-24 | 2012-08-02 | Dow Global Technologies Llc | Composite polyamide membrane |
| US8968828B2 (en) | 2011-01-24 | 2015-03-03 | Dow Global Technologies Llc | Composite polyamide membrane |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8404855D0 (en) | 1984-03-28 |
| GB2139113B (en) | 1987-02-18 |
| CA1220990A (en) | 1987-04-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20020224 |