WO1990002602A1 - Chlorine-resistant semipermeable membranes - Google Patents
Chlorine-resistant semipermeable membranes Download PDFInfo
- Publication number
- WO1990002602A1 WO1990002602A1 PCT/US1988/003171 US8803171W WO9002602A1 WO 1990002602 A1 WO1990002602 A1 WO 1990002602A1 US 8803171 W US8803171 W US 8803171W WO 9002602 A1 WO9002602 A1 WO 9002602A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- membrane
- chlorine
- aromatic
- chloride
- set forth
- Prior art date
Links
- 239000012528 membrane Substances 0.000 title claims abstract description 181
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 title claims abstract description 30
- 239000000460 chlorine Substances 0.000 title claims abstract description 30
- 229910052801 chlorine Inorganic materials 0.000 title claims abstract description 30
- 125000003118 aryl group Chemical group 0.000 claims abstract description 75
- 239000000243 solution Substances 0.000 claims abstract description 54
- 239000000463 material Substances 0.000 claims abstract description 37
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000002131 composite material Substances 0.000 claims abstract description 30
- 229920000768 polyamine Polymers 0.000 claims abstract description 30
- 125000001309 chloro group Chemical group Cl* 0.000 claims abstract description 28
- 239000007864 aqueous solution Substances 0.000 claims abstract description 25
- NGNBDVOYPDDBFK-UHFFFAOYSA-N 2-[2,4-di(pentan-2-yl)phenoxy]acetyl chloride Chemical compound CCCC(C)C1=CC=C(OCC(Cl)=O)C(C(C)CCC)=C1 NGNBDVOYPDDBFK-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000007795 chemical reaction product Substances 0.000 claims abstract description 18
- 238000010612 desalination reaction Methods 0.000 claims abstract description 14
- 239000003960 organic solvent Substances 0.000 claims abstract description 12
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 68
- 239000011780 sodium chloride Substances 0.000 claims description 36
- 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 description 28
- 238000000034 method Methods 0.000 claims description 25
- 230000008569 process Effects 0.000 claims description 20
- 239000012466 permeate Substances 0.000 claims description 15
- VZNUCJOYPXKLTA-UHFFFAOYSA-N 5-chlorobenzene-1,3-diamine Chemical compound NC1=CC(N)=CC(Cl)=C1 VZNUCJOYPXKLTA-UHFFFAOYSA-N 0.000 claims description 13
- 238000006482 condensation reaction Methods 0.000 claims description 13
- ZWUBBMDHSZDNTA-UHFFFAOYSA-N 4-Chloro-meta-phenylenediamine Chemical compound NC1=CC=C(Cl)C(N)=C1 ZWUBBMDHSZDNTA-UHFFFAOYSA-N 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 8
- FDQSRULYDNDXQB-UHFFFAOYSA-N benzene-1,3-dicarbonyl chloride Chemical compound ClC(=O)C1=CC=CC(C(Cl)=O)=C1 FDQSRULYDNDXQB-UHFFFAOYSA-N 0.000 claims description 6
- 238000005266 casting Methods 0.000 claims description 5
- 238000002360 preparation method Methods 0.000 claims description 4
- LXEJRKJRKIFVNY-UHFFFAOYSA-N terephthaloyl chloride Chemical compound ClC(=O)C1=CC=C(C(Cl)=O)C=C1 LXEJRKJRKIFVNY-UHFFFAOYSA-N 0.000 claims description 3
- 239000002736 nonionic surfactant Substances 0.000 claims description 2
- 229920002492 poly(sulfone) Polymers 0.000 abstract description 42
- 239000013535 sea water Substances 0.000 abstract description 17
- 238000000926 separation method Methods 0.000 abstract description 9
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 53
- 230000004907 flux Effects 0.000 description 30
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 20
- 238000001223 reverse osmosis Methods 0.000 description 16
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 15
- 125000001424 substituent group Chemical group 0.000 description 14
- 239000002904 solvent Substances 0.000 description 11
- 239000010409 thin film Substances 0.000 description 11
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 10
- 229920000642 polymer Polymers 0.000 description 10
- 150000003839 salts Chemical class 0.000 description 10
- 235000019333 sodium laurylsulphate Nutrition 0.000 description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 8
- 239000011148 porous material Substances 0.000 description 8
- 238000012695 Interfacial polymerization Methods 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- 238000011282 treatment Methods 0.000 description 7
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 6
- 150000004982 aromatic amines Chemical class 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 6
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 4
- 230000009471 action Effects 0.000 description 4
- -1 aromatic tricarboxylic acid derivatives Chemical class 0.000 description 4
- 238000005660 chlorination reaction Methods 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 230000002452 interceptive effect Effects 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 239000004094 surface-active agent Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- GEYOCULIXLDCMW-UHFFFAOYSA-N 1,2-phenylenediamine Chemical compound NC1=CC=CC=C1N GEYOCULIXLDCMW-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 150000001266 acyl halides Chemical class 0.000 description 3
- 150000001412 amines Chemical class 0.000 description 3
- 125000003277 amino group Chemical group 0.000 description 3
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 3
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 description 2
- RGSFGYAAUTVSQA-UHFFFAOYSA-N Cyclopentane Chemical compound C1CCCC1 RGSFGYAAUTVSQA-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 239000004952 Polyamide Substances 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 150000001408 amides Chemical class 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 230000001627 detrimental effect Effects 0.000 description 2
- 150000004820 halides Chemical class 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 229940018564 m-phenylenediamine Drugs 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- GDOPTJXRTPNYNR-UHFFFAOYSA-N methylcyclopentane Chemical compound CC1CCCC1 GDOPTJXRTPNYNR-UHFFFAOYSA-N 0.000 description 2
- 229920002647 polyamide Polymers 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 150000003141 primary amines Chemical group 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- BOSAWIQFTJIYIS-UHFFFAOYSA-N 1,1,1-trichloro-2,2,2-trifluoroethane Chemical compound FC(F)(F)C(Cl)(Cl)Cl BOSAWIQFTJIYIS-UHFFFAOYSA-N 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical class CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 1
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000005708 Sodium hypochlorite Substances 0.000 description 1
- 239000005862 Whey Substances 0.000 description 1
- 102000007544 Whey Proteins Human genes 0.000 description 1
- 108010046377 Whey Proteins Proteins 0.000 description 1
- PBCJIPOGFJYBJE-UHFFFAOYSA-N acetonitrile;hydrate Chemical compound O.CC#N PBCJIPOGFJYBJE-UHFFFAOYSA-N 0.000 description 1
- 230000010933 acylation Effects 0.000 description 1
- 238000005917 acylation reaction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 230000029936 alkylation Effects 0.000 description 1
- 238000005804 alkylation reaction Methods 0.000 description 1
- 125000000732 arylene group Chemical group 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000008199 coating composition Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 239000007859 condensation product Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000000994 depressogenic effect Effects 0.000 description 1
- 150000004985 diamines Chemical class 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000008233 hard water Substances 0.000 description 1
- DMEGYFMYUHOHGS-UHFFFAOYSA-N heptamethylene Natural products C1CCCCCC1 DMEGYFMYUHOHGS-UHFFFAOYSA-N 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000002563 ionic surfactant Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 238000012643 polycondensation polymerization Methods 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000002954 polymerization reaction product Substances 0.000 description 1
- 229920001955 polyphenylene ether Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920001451 polypropylene glycol Polymers 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical class CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 1
- 239000008213 purified water Substances 0.000 description 1
- 239000002516 radical scavenger Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000012465 retentate Substances 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000000108 ultra-filtration 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
- B01D69/1213—Laminated layers
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/48—Polymers modified by chemical after-treatment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
- B01D67/0006—Organic membrane manufacture by chemical reactions
-
- 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
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
- C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids
- C08G69/32—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids from aromatic diamines and aromatic dicarboxylic acids with both amino and carboxylic groups aromatically bound
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/08—Specific temperatures applied
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/12—Specific ratios of components used
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/15—Use of additives
- B01D2323/216—Surfactants
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/30—Chemical resistance
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/08—Seawater, e.g. for desalination
Definitions
- the separation of various components found in liquids or gases may be effected in a multitude of processes, the techniques for effecting the separation including ultrafiltration or reverse osmosis.
- a particular example of the latter type of separation involves a desalination process in which water which is rendered potable or suitable for other purposes is obtained from sea water, contaminated water, brackish water or brine. This process is of especial value in areas of the world where the water found in the area is brackish or is saline in nature. The desalination of this water is necessary in order to provide large amounts of potable or relatively nonsalty water for industrial, agricultural or home use.
- the desalination of the water is effected by forcing the water through a reverse osmosis membrane whereby the purified water is passed through the membrane and recovered, while the contaminants or salts do not pass through the membrane, thus, in effect, being rejected by the membrane and recovered as the retentate.
- a reverse osmosis membrane in order to be utilized for such a purpose, must possess certain characteristics applicable to the process. For example, the membrane must have a very high salt rejection coefficient. In addition, another important characteristic and a problem which must be addressed when utilizing the membrane, is the ability of the membrane to be resistant to chlorine attack. Another important factor which is present in the use of a reverse osmosis membrane is that said membrane also possess a high flux characteristic, that is, the ability to pass a relatively large amount of water through the membrane at relatively low pressures. If a membrane possesses these desirable characteristics, it will be commercially feasible in its applicability to the desalination process. Reverse osmosis membranes have been prepared and used from a wide variety of known polymeric materials.
- 3,260,691 and 3,480,588 disclose coating compositions which are obtained from the condensation products of aromatic primary diamines and aromatic tricarboxylic acid derivatives.
- the semipermeable membrane which is used for the desalination process should be relatively thin in nature in order to provide a desirable flux rate
- This porous support backing material should in itself possess certain characteristics which make it desirable for such a use.
- the porous support material should possess pore sizes which are sufficiently large enough so that the water or permeate can pass through the support without affecting or lessening the flux rate of the entire composite.
- the pore size should not be large enough so that the thin composite semipermeable membrane will tend to fill up or enter into the pores, thus distorting the shape of the thin film membrane with the attendant possibility of rupturing the membrane, thus causing said membrane to lose its effectiveness in the reverse osmosis process.
- another U.S. Patent namely 4,277,344 discloses an interfacial synthesized reverse osmosis membrane. This membrane is prepared from a cross-linked interfacially polymerized aromatic polyamine which has been prepared from an essentially monomeric polyacyl halide and an essentially monomeric arylene polyamine.
- acyl halide which is employed as one of the components in the interfacial polymerization reaction should be free of interfering substituents.
- the patent refers to these substituents as moieties which are capable of interfering with intermolecular amine- carboxylic acid, amide-forming condensation reactions and points out that such interference is generally steric and/or chemically reactive.
- An example of steric interference or steric hindrance would be the location of a substituent other than hydrogen on a ring position adjacent to an amine group on the polyamine reactant.
- An example of chemical interference would be the location of an acyl halide reactive substituent on the polyacyl halide or an amine-reactive substituent on the polyamine.
- polymerized aromatic polyamine of this patent which may be depicted as follows:
- the chlorine substituent is on the aromatic ring portion of the polyamine, the dotted lines connecting the chlorine substituent to the ring indicating that the chlorine may be either in the 4 or 5 position depending upon the particular compound which has been chosen as one of the components of the desired membrane.
- Another Patent, No. 3,948,823 discloses the preparation of membranes from blends of preformed polymers. These membranes comprise a vastly different concept from the membranes of the present invention which are prepared by an interfacial condensation polymerization of reactive monomers on the surface of an inert support polymer.
- the polymers which are taught by this reference are not soluble in solvents which are compatible with the support polymers utilized in the present invention. Therefore, an attempt to cast a solution of a polymer as taught by this patent on the surface of a support polymer which is utilized in the present invention would result in the dissolution of the support polymer rather than in the formation of a composite membrane which is the present invention.
- semipermeable membranes which possess the desirable characteristics of high salt rejection, good flux and high resistance to chlorine may be prepared in an interfacial polymerization reaction utilizing an aromatic polycarboxylic acid chloride and an aromatic polyamine in which the chlorine may be situated on a carbon atom adjacent to a primary amine group as the reactive components.
- This invention relates to reverse osmosis membranes. More specifically, the invention is concerned with reverse osmosis membranes which exhibit an extreme resistance to chlorine degradation.
- reverse osmosis membranes for the separation of liquid from liquid or solids from liquids are important articles of commerce. This is especially true in the area of desalination whereby water which is brackish or saline in nature may be rendered potable or suitable for use in other industrial or agricultural regions by passing the water through reverse osmosis membranes.
- the particular membranes which constitute the inventive feature of the present application will comprise the reaction product resulting from the reaction of a aromatic polyamine and an aromatic polycarboxylic acid chloride, said membrane being composited or coated on a porous support backing material.
- a further object of this invention is to provide a process for preparing a semipermeable membrane which is resistant to chlorine, thus rendering the membrane suitable for use in separation processes such as desalination of water where chlorine is present in an amount sufficient to degrade other types of membranes.
- an embodiment of this invention resides in a chlorine-resistant semipermeable membrane comprising a porous support backing material having supported thereon an interfacial polymerized condensation reaction product formed by the process of reacting together an aromatic polyamine containing a chlorine substituent on the aromatic ring and an aromatic polycarboxylic acid chloride.
- Another embodiment of this invention resides in a process for the preparation of a chlorine-resistant semipermeable membrane which comprises casting a solution of an aromatic polyamine containing a chlorine substituent on the aromatic ring on a porous support backing material, removing excess solution, contacting said coated support material with an organic solvent solution of an aromatic polycarboxylic acid chloride to form an interfacial condensation reaction product membrane on the surface of said porous backing material, curing the resultant composite at curing conditions, and recovering the resultant chlorine-resistant semipermeable membrane.
- a specific embodiment of this invention is found in a chlorine-resistant semipermeable membrane comprising polysulfone having supported thereon the interfacial polymerized condensation reaction product resulting from the reaction of 4-chloro-m- phenylenediamine or 5-chloro-m-phenylenediamine with trimesoyl chloride.
- Another specific embodiment of this invention resides in a process for the preparation of a chlorine- resistant semipermeable membrane which comprises casting an aqueous solution of 4-chloro-m-phenylenediamine or 5- chloro-m-phenylenediamine on a porous backing support material comprising polysulfone, removing excess solution, contacting said coated polysulfone with a hexane solution of trimesoyl chloride to form an interfacial polymerized condensation reaction product membrane on the surface of said polysulfone, curing the resultant composite at a temperature in the range of from about 25° to about 150°C for a period of time in the range of from about 10 minutes to about two hours, and recovering the resultant chlorine-resistant semipermeable membrane.
- the present invention is concerned with semipermeable membranes which are resistant to chlorine.
- the membranes are prepared by casting an aqueous solution of an aromatic polyamine which contains a chlorine substituent on the aromatic ring of the compound on a porous backing support material, removing excess solution, and thereafter contacting the coated support material with an organic solvent solution of an aromatic polycarboxylic acid chloride.
- the organic solvent which is used to prepare the solution of the aromatic polycarboxylic acid chloride is immiscible with the aqueous solution, thus permitting the formation of an interfacial polymerized condensation reaction product on the surface of.the support material.
- the resulting composite is then cured to provide a semipermeable membrane which exhibits favorable characteristics with respect to salt rejection and flux as well as resistance to chlorine.
- the membrane of the present invention which is formed from the interfacial polymerization of an aromatic polyamine containing a chlorine substituent on the aromatic ring in a position either ortho or meta to an amine substituent and an aromatic polycarboxylic acid chloride will possess chlorine-resistant properties which are either equal to or superior to other membranes which are not formed from the reaction of these two components and which will exhibit a resistance to chlorine.
- the membranes of the present invention will not require further modification or treatment, such as that taught in a prior patent, to enhance the desired properties of the membrane.
- aromatic polyamines containing a chlorine substituent on the aromatic ring which comprise one component of the product of the present invention will comprise either 4-chloro-m-phenylenediamine or 5-chloro- m-phenylenediamine. It is also contemplated within the scope of this invention that aromatic polyamines containing a chlorine substituent on the aromatic ring in which the amine moieties are in a position para to each other may also be employed, however not necessarily with equivalent results.
- the aromatic polycarboxylic acid chloride which forms the other component necessary to form the interfacial polymerization product will comprise either di- or tricarboxyli ⁇ acid chloride such as trimesoyl chloride (1,3,5-benzene tricarboxylic acid chloride) , isophthaloyl chloride, terephthaloyl chloride as well as mixtures of trimesoyl chloride and the isomeric phthaloyl chlorides.
- the chlorine-resistant semipermeable membranes of the present invention may be prepared by coating the porous support backing material with an aqueous solution of the aromatic polyamine containing a chlorine substituent on the aromatic ring.
- the porous support backing material comprises a polymeric material containing pore sizes which are sufficient to permit the passage of permeate therethrough but are not large enough so as to interfere with the bridging over of the resulting ultrathin reverse osmosis membrane.
- the pore sizes of the porous support backing material will range from about 1 to about 1000 millimicrons inasmuch as pores which are larger than 1000 millimicrons will permit the ultrathin reverse osmosis membrane to sag into the pore, thus disrupting the flat sheet configuration which is a desirable characteristic of the membrane.
- porous support backing material which may be used to prepare the desired membrane composite will include such polymers as polysulfone, polycarbonate, microporous polypropylene, the various polyamides, polyphenylene ether, etc.
- the porous support backing material is coated with an aqueous solution of the aromatic amine containing a chlorine substituent on the aromatic ring utilizing either a hand casting or continuous operation.
- the solution which is utilized as the carrier for the aromatic amine containing a chlorine substituent on the aromatic ring will be 100% water or 100% acetonitrile or intermediate mixtures of water and acetonitrile.
- the aromatic amine containing a chlorine substituent on the aromatic ring will be present in the solution in an amount in the range of from about 0.1 to about 5% by weight of the solution.
- the solution may also contain additional components which, while not entering into the reaction, provide additional assistance in formulating the desired interfacial polymerization reaction product.
- additives examples include surfactants including ionic surfactants such as sodium lauryl sulfate, lower molecular weight alcohols such as ethanol, ethanol, ethylene glycol, the isomeric propanols, butanols, or nonionic surfactants such as polyethylene glycol, polypropylene glycol, copolymers of ethylene glycol and propylene glycol, etc.
- the aqueous solution may also contain basic acid scavengers such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, etc.
- the excess solution is drained and the coated support material is then contacted with an organic solvent solution of the aromatic polycarboxylic acid chloride.
- the aromatic polycarboxylic acid chloride is present in the organic solvent solution in a range of from about 0.1 to about 5% by weight of the solution.
- the organic solvents which are employed in the process of this invention will comprise paraffins such as ⁇ -pentane, n-hexane, n- heptane, cyclopentane, cyclohexane, methylcyclopentane, etc. or, a halogenated solvent such as trichlorotrifluoroethane.
- the polymerization of the two components of the membrane will occur substantially only at the interface between the solvent phases and thus an interfacially polymerized reaction product comprising a thin film membrane will be formed thereat.
- the contact time required for the formation of the thin film membrane will fluctuate over a relatively wide range of from about 1 second to about 60 seconds.
- the resultant composite may be cured to remove any remaining solvent and firmly affix the thin film membrane on the surface of the support.
- the curing of the composite membrane may be effected over a wide temperature range, said temperature being from ambient (20°-25°C) up to about 150°C for a period of time ranging from about 1 minute to about 2 hours or more in duration.
- the operating parameters of time and temperature will be interdependent, the primary criteria for the curing of the membrane being that said curing time is sufficient to provide the desired membrane but being insufficient to affect the desired characteristics of the thin film membrane and the porous backing support material. For example, excessive heat or curing time may affect the pore size of the backing material, thus resulting in a decrease of the desired flux rate of the membrane.
- the chlorine-resistant semipermeable membrane may be prepared in a continuous manner of operation.
- a porous support backing material of the type hereinbefore set forth in greater detail is continuously passed through a bath of an aqueous solution of the aromatic polyamine containing a chlorine substituent on the aromatic ring, said solution also containing, if so desired, a surfactant and an acid scavenger.
- the backing material is continuously withdrawn and, if so desired, passed between rollers in order to remove any excess solution which may be present.
- the coated support material is then also continuously passed through the solution of the aromatic polycarboxylic acid chloride in an organic solvent.
- the interfacial polymerization reaction will occur during the contact time between the solutions following which the composite comprising the interfacial polymerized reaction product in the form of a thin film semipermeable membrane on the porous support backing material will then be cured as, for example, by passage through an oven which is maintained at a desired curing temperature, the passage through said oven being at a predetermined rate so as to avoid any possible damage to the composite membrane.
- the resultant chlorine-resistant semipermeable membrane may then be employed for the separation process desired such as the desalination of sea water or brackish water, other treatments of water such as softening of hard water whereby salts are removed, boiling said water treatment, concentration of whey, etc.
- the membranes which are in the form of flat sheets are particularly applicable for use in modules either in single sheet or multiple sheet units whereby the sheet or sheets are wound in a spiral type configuration.
- a chlorine-resistant semipermeable membrane was prepared by handcasting a solution comprising 1.0% by weight of 4-chloro-js-phenylenediamine in a solvent comprising 97% of a 50/50 mixture of acetonitrile and water and 3% isopropanol on a 8" by 10" sheet of polysulfone at ambient temperature and pressure.
- the excess solution was drained after a period of 30 seconds, and the coated polysulfone contacted with a solution comprising 0.5% by weight of trimesoyl chloride in a hexane solvent. After a period of 30 seconds, the excess organic solvent was drained and the resultant semipermeable membrane composite was washed with water.
- the membrane composite which may be designated as a poly(chlorophenylenediamine trimesamide) , was then cured at a temperature of 70°C for a period of 30 minutes.
- a sample of the membrane prepared according to the above paragraph in a size of 1" x 3" was placed in a cell and a synthetic sea water feed containing 5000 ppm of sodium chloride was passed across the surface of the membrane at a feed flow rate of 1.3 gal/min (GPM) .
- the test conditions which were employed during the experiment included a pressure of 800 pounds per square inch (psi) on one side of the membrane while the other side of the membrane was maintained at atmospheric pressure.
- a temperature of 25°C was maintained throughout the experiment while keeping the pH of the feed at 5.5.
- the permeate which was collected from the flowthrough was measured and it was found that there was a 93.5% rejection of sodium chloride at a flux rate of 8.6 GFD.
- a membrane was prepared in a manner similar to that set forth in Example I above by contacting an 8" x 10" sheet of polysulfone with a solution comprising 2.0% by weight of 4-chloro-m-phenylenediamine in a 97% water and 3% isopropanol solvent at ambient temperature and pressure for a period of 30 seconds. The excess solution was drained and the coated polysulfone support was contacted with an organic solution comprising 0.25% by weight of trimesoyl chloride in hexane. After allowing a contact period of 30 seconds, the resulting membrane composite was washed with water and dried at a temperature of 70°C for a period of 30 minutes.
- a membrane composite was prepared by coating an 8" x 10" sheet of polysulfone with a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate, and 1.0% by weight of 5-chloro-m- phenylenedia ine at ambient temperature and pressure for a period of 30 seconds, and then draining.
- the coated polysulfone was then contacted with an organic solution comprising 1.0% by weight of trimesoyl chloride in hexane, the contact being effected at ambient temperature and pressure for a period of 30 seconds.
- the resulting thin film interfacial polymerized condensation reaction product semipermeable membrane composited on polysulfone was then cured at a temperature of 70°C for a period of 30 minutes.
- a 1" x 3" sample of the thus prepared membrane was placed in a cell and subjected to a synthetic sea water feed containing 5000 ppm of sodium chloride.
- a charge to the surface of the membrane was effected at a pressure of 800 psi while maintaining the temperature at 25°C and the pH of the feed at 5.5.
- Analysis of the permeate disclosed a 97.2% sodium chloride rejection at a flux rate of 19.6 GFD.
- a membrane similar in nature to that prepared in the first paragraph of this example was prepared using a similar technique. However, the organic solution which was employed to effect the interfacial polymerization on the surface of the polysulfone contained only 0.5% by weight of trimesoyl chloride.
- the membrane when subjected to the action of a synthetic sea water feed under conditions similar to that hereinbefore set forth gave a 97.8% sodium chloride rejection at a flux of 22.5 GFD.
- Another sample of this membrane when subjected to the action of a synthetic sea water feed comprising 35,000 ppm of sodium chloride, under similar conditions to those hereinbefore set forth, gave a 97.4% sodium chloride rejection at a flux rate of 10.9 GFD.
- a series of membranes were prepared by coating a polysulfone support with a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate, and 1.0% by weight of 5-chloro-m- phenylenediamine for a period of 30 seconds. After draining the excess solution from the coated support, it was then contacted with an organic solution containing 0.1% by weight of trimesoyl chloride in hexane. After a contact time of 30 seconds had elapsed, the excess solution was removed and the membrane was cured in an oven at a temperature of 70°C for a period of 30 minutes.
- a membrane composite was prepared by coating an 8" x 10" sheet of polysulfone with a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate and 1.0% by weight of 5-chloro-m- phenylenediamine at ambient temperature and pressure. Contact was maintained for a period of 30 seconds, then the excess aqueous solution was drained. The coated polysulfone was then contacted with an organic solution comprising 0.45% by weight of trimesoyl chloride and 0.05% by weight of isophthaloyl chloride in hexane, the contact being effected at ambient temperature and pressure for a period of 30 seconds. The excess organic solution was removed by draining, and the resulting thin film interfacial polymerized condensation reaction product semipermeable membrane composited on polysulfone was then cured at a temperature of 70°C for a period of 30 minutes.
- a 1" x 3" sample of the thus prepared membrane was placed in a cell and subjected to a synthetic sea water feed containing 5000 ppm of sodium chloride.
- a charge to the surface of the membrane was effected at a pressure of 800 psi while maintaining the temperature at 25°C and the pH of the feed at 5.5.
- Analysis of the permeate disclosed a 93.4% rejection of sodium chloride at a flux rate of 24.3 GFD.
- a membrane composite was prepared by coating an 8" x 10" sheet of polysulfone with a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate, 0.50% by weight of 5-chloro-m- phenylenediamine, and 0.50% by weight of 4-chloro-m- phenylenediamine at ambient temperature and pressure. Contact was maintained for a period of 30 seconds, then the excess aqueous solution was drained.
- the coated polysulfone was then contacted with an organic solution comprising 0.5% by weight of trimesoyl chloride in hexane, the contact being effected at ambient temperature and pressure for a period of 30 seconds.
- the excess organic solution was removed by draining, and the resulting membrane composite was then cured at a temperature of 70°C for a period of 30 minutes.
- the membrane when subjected to the action of a synthetic sea water feed under conditions similar to that hereinbefore set forth gave a 77.9% sodium chloride rejection at a flux rate of 11.96 GFD.
- a membrane composite was prepared by coating an 8" x 10" sheet of polysulfone with a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate, 0.50% by weight of 5-chloro-m- phenylenediamine, and 0.50% by weight of 4-chloro-m- phenylenediamine at ambient temperature and pressure. Contact was maintained for a period of 30 seconds, after which the excess aqueous solution was removed by draining.
- the coated polysulfone was then contacted with an organic solution comprising 0.45% by weight of trimesoyl chloride and 0.05% by weight of isophthaloyl chloride in hexane, the contact being effected at ambient temperature and pressure for a period of 30 seconds.
- the excess organic solution was removed by draining, and the resulting membrane composite thus produced was then cured at a temperature of 70°C for a period of 30 minutes.
- a 1" x 3" sample of the composite membrane was placed in a cell and subjected to a synthetic sea water feed containing 5000 ppm of sodium chloride.
- a charge to the surface of the membrane was effected at a pressure of 800 psi while maintaining the temperature at 25°C and the pH of the feed at 5.5.
- Analysis of the permeate showed a sodium chloride rejection of 70.9% at a flux rate of 18.6 GFD.
- a membrane was prepared using a continuous casting technique. The process was effected by continuously passing a sheet of polysulfone through a bath of 1.0% by weight of 4-chloro-m- phenylenediamine in a 50/50% solution of acetonitrile and water which contained 0.02% by weight of a surfactant comprising sodium lauryl sulfate. The rate of passage of the polysulfone sheet through the bath was effected at a speed of 0.33 feet per minute at atmospheric pressure and ambient temperature. The contact of the polysulfone sheet with the water-acetonitrile solution lasted for a period of 20 seconds.
- the sheet of coated polysulfone was continuously withdrawn and the excess aqueous solution was drained therefrom. Following this, the sheet was continuously passed through a bath of hexane which contained 1.0% by weight of trimesoyl chloride. The contact of the coated polysulfone sheet with the organic solution lasted for a period of 20 seconds. Thereafter the thin film semipermeable membrane composited on the surface of the polysulfone was recovered and subjected to a curing step in an oven at a temperature of 80°C for a period of 30 minutes.
- a 1" x 3" sample of the thus prepared membrane was placed in a cell and a feedstock comprising a synthetic sea water feed which contained 5000 ppm of sodium chloride was passed over the surface of the membrane at a temperature of 25°C and at a pressure of 800 psi on one side of the membrane, the other side of the membrane being maintained at atmospheric pressure.
- the permeate was analyzed and it was found that there had been a 97.9% rejection of the sodium chloride at a flux rate of 4.6 GFD.
- a similar membrane which was prepared from a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate, and 1.0% by weight of 4-chloro-m- phenylenediamine which was contacted with an organic solution of hexane containing 1.0% by weight of trimesoyl chloride resulted in a membrane which, after having been cured at a temperature of 70°C for a period of 45 minutes, gave a rejection of 97.1% of sodium chloride at a flux rate of 8.3 GFD.
- a membrane was prepared by continuously passing a polysulfone sheet through a bath which comprised 2.0% by weight of 4-chloro-m- phenylenediamine in a solvent of a 50/50 mixture of acetonitrile and water at ambient temperature and pressure, the passage of the polysulfone sheet through the bath being effected at a rate of 0.33 ft./min. with a contact time of 20 seconds.
- the polysulfone sheet was continuously withdrawn from the bath and after excess solution had been drained, it was continuously charged to a hexane solution which contained 0.84% by weight of trimesoyl chloride and 0.16% by weight of isophthaloyl chloride.
- the membrane composite was withdrawn and cured at a temperature of 70°C for a period of 30 minutes.
- a 1" x 3" sample of the membrane prepared according to the above paragraph was subjected to a desalination reaction in a manner similar to that hereinbefore set forth utilizing a synthetic sea water feed containing 5000 ppm of sodium chloride. The feed was passed over the surface of the membrane at a rate of 1.3 GPM at a pressure of 800 psi and a temperature of 25°C. Analysis of the permeate which was recovered showed that there had been an 83.7% rejection of the sodium chloride at a flux rate of 4.7 GFD.
- a membrane was prepared using a continuous casting technique. The process was effected by continuously passing a sheet of polysulfone through a bath of 0.6% by weight of 5-chloro-m- phenylenediamine in water which contained 20 ppm of a surfactant comprising sodium lauryl sulfate. The rate of passage of the polysulfone sheet through the bath was effected at a speed of 2.0 feet per minute at atmospheric pressure and ambient temperature. The contact time of the polysulfone sheet with the aqueous solution lasted for a period of 9 seconds. The sheet of coated polysulfone was continuously withdrawn and the excess aqueous solution was drained therefrom.
- the sheet was continuously passed through a bath of hexane which contained 0.5% by weight of trimesoyl chloride.
- the contact of the coated polysulfone sheet with the organic solution lasted for a period of 9 seconds.
- the thin film semipermeable membrane composited on the surface of the polysulfone was recovered and subjected to a curing step in an oven at a temperature of 72° ⁇ 2°C.
- a 1" x 3" sample of the thus prepared membrane was placed in a cell and a feedstock comprising a synthetic sea water feed which contained 5000 ppm of sodium chloride was passed over the surface of the membrane at a temperature of 25°C, a pH of 5.5, and at a pressure of 800 psi applied on one side of the membrane, the other side of the membrane being maintained at atmospheric pressure.
- the feed flow rate was 1.3 GPM.
- the permeate was analyzed and it was found that there had been a 99.14% rejection of the sodium chloride at a flux rate of 8.1 GFD.
- a membrane composite was prepared by a method similar to that taught in U.S. Patent 4,277,344.
- An 8" x 10" sheet of polysulfone was coated with an aqueous solution containing 1.0% by weight of m-phenylenediamine at ambient temperature and pressure for a period of 30 seconds. After draining the excess aqueous solution, the coated polysulfone was then contacted with an organic solution comprising 0.5% by weight of trimesoyl chloride in hexane, the contact being effected at ambient temperature and pressure for a period of 30 seconds.
- the resulting thin film interfacial polymerized condensation reaction product semipermeable membrane composited on polysulfone was then cured at a temperature of 70°C for a period of 30 minutes, and was then evaluated as described in Example XII.
- a 1" x 3" sample of each composite membrane was placed in a cell and subjected to a synthetic sea water feed containing 5000 ppm of sodium chloride at a feed flow rate of 1.3 GPM.
- a charge to the surface of the membrane was effected at a pressure of 800 psi while maintaining the temperature at 25°C and the pH of the feed at 5.5. After 1 hour under these test conditions, the permeate from each cell was analyzed.
- hypochlorite was added to the above synthetic sea water feed to give an effective sodium hypochlorite concentration of 4 ppm.
- the membrane samples in the cells were then subjected to this hypochlorite containing feed under the same operating conditions described above. After 2 hours under these test conditions, the permeate from each cell was analyzed.
- the membrane sample prepared according to Example VIII from 4-chloro-m-phenylenediamine and trimesoyl chloride showed increases in both sodium chloride rejection and flux rate, while the membrane sample prepared according to Example XI from m- phenylenediamine and trimesoyl chloride showed a smaller increase in sodium chloride rejection and a decrease in flux rate:
- a 1" x 3" sample of the thus prepared composite membrane was placed in a cell and subjected to a synthetic sea water feed containing 2000 ppm of sodium chloride at a feed flow rate of 1.3 GPM.
- a charge to the surface of the membrane was effected at a pressure of 420 psi while maintaining the temperature at 25°C and the pH of the feed at 5.7 to 5.9.
- Hypochlorite was introduced into the feed periodically as described in Example XII, with a total accumulated exposure of 1360 ppm-hours.
- the permeate from the cell was periodically analyzed for sodium chloride rejection and flux rate. Although flux rate was depressed during the hypochlorite exposure, it was restored after exposure to hypochlorite-free feed.
- Sodium chloride rejection exhibited a modest improvement after this treatment:
- membranes could be prepared from a phenylenediamine containing a chlorine substituent on the aromatic ring which would be comparable in nature to those which did not contain a substituent on the aromatic ring of the phenylenediamine contrary to teachings of U. S. Patent 4,277,344, a series of membranes were prepared according to the teachings of this patent and compared to membranes which were prepared according to the process of the present invention.
- the membranes of the present invention and those of the U. S. Patent were subjected to a soak treatment of 1 ppm of hypochlorite for a period of 1 hour and a period of 16 hours.
- the membranes were subjected to a reverse osmosis treatment in a manner similar to that set forth in the above examples, the water feed containing 5000 ppm of sodium chloride at a feed flow rate of 1.3 GPM.
- the feed was charged to the surface of the membrane at a pressure of 800 psi while maintaining the temperature at 25°C and the pH of the feed at 5.5.
- the results of this test are set forth in the Table below.
- the membranes labeled A, B, and C are those membranes prepared according to the teachings of U. S. Patent 4,277,344, and membranes D, E, and F are those which comprise the interfacial polymerized condensation reaction product of 5-chloro-m-phenylenediamine and trimesoyl chloride as described in Example IV of this application.
- a membrane could be prepared from a phenylenediamine containing a chlorine substituent on the aromatic ring and trimesoyl chloride which is comparable in nature to the membrane of the patent and that, contrary to the teachings of the patent in Examples XV and XVI thereof, discloses that the membrane of the patent exhibits both decreased salt rejection and decreased flux.
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Abstract
Chlorine-resistant semipermeable membranes which comprise an interfacial polymerized reaction product composited on a porous support backing material may be prepared by contacting a porous support material such as polysulfone with an aqueous solution of an aromatic polyamine containing a chlorine substituent on the aromatic ring. The coated support material is then contacted with an organic solvent solution of aromatic polycarboxylic acid chloride for a period of time sufficient to form an interfacial polymerized reaction product on the surface of the support material. The resultant membrane composite may be used in separation processes such as desalination of brackish or sea water, the membrane being resistant to attack by chlorine which is present in the water.
Description
CHLORINE-RESISTANT SEMIPERMEABLE MEMBRANES
BACKGROUND OF THE INVENTION The separation of various components found in liquids or gases may be effected in a multitude of processes, the techniques for effecting the separation including ultrafiltration or reverse osmosis. A particular example of the latter type of separation involves a desalination process in which water which is rendered potable or suitable for other purposes is obtained from sea water, contaminated water, brackish water or brine. This process is of especial value in areas of the world where the water found in the area is brackish or is saline in nature. The desalination of this water is necessary in order to provide large amounts of potable or relatively nonsalty water for industrial, agricultural or home use. The desalination of the water is effected by forcing the water through a reverse osmosis membrane whereby the purified water is passed through the membrane and recovered, while the contaminants or salts do not pass through the membrane, thus, in effect, being rejected by the membrane and recovered as the retentate.
A reverse osmosis membrane, in order to be utilized for such a purpose, must possess certain characteristics applicable to the process. For example, the membrane must have a very high salt rejection coefficient. In addition, another important characteristic and a problem which must be addressed when utilizing the membrane, is the ability of the membrane to be resistant to chlorine attack. Another important factor which is present in the use of a reverse osmosis membrane is that said membrane also possess a high flux characteristic, that is, the ability to pass a relatively large amount of water through the membrane at relatively low pressures. If a membrane possesses these desirable characteristics, it will be commercially feasible in its applicability to the desalination process.
Reverse osmosis membranes have been prepared and used from a wide variety of known polymeric materials. While many of these polymeric materials possess the ability of reducing the concentration of a solute to where the salt rejection capability is in excess of 98%, some do not possess the necessary flux rate whereby the volume of water which is required to be produced by the membrane per unit of membrane surface is sufficient for the application of the technology. As was hereinbefore set forth, many prior U.S. patents describe various membranes which are useful in desalination processes. For example, U.S. Patent Nos. 3,567,632, 3,600,350, 3,710,945, 3,878,109, 3,904,519, 3,920,612, 3,951,815, 3,993,625 and 4,048,144 illustrate various semipermeable membranes prepared from polyamides. Likewise, U.S. Patent Nos. 3,260,691 and 3,480,588 disclose coating compositions which are obtained from the condensation products of aromatic primary diamines and aromatic tricarboxylic acid derivatives. Inasmuch as the semipermeable membrane which is used for the desalination process should be relatively thin in nature in order to provide a desirable flux rate, it is necessary, in many instances, that the reverse osmosis membrane be composited or laminated on a porous backing support material. This porous support backing material should in itself possess certain characteristics which make it desirable for such a use. For example, the porous support material should possess pore sizes which are sufficiently large enough so that the water or permeate can pass through the support without affecting or lessening the flux rate of the entire composite. Conversely speaking, the pore size should not be large enough so that the thin composite semipermeable membrane will tend to fill up or enter into the pores, thus distorting the shape of the thin film membrane with the attendant possibility of rupturing the membrane, thus causing said membrane to lose its effectiveness in the reverse osmosis process.
In addition to the aforementioned U.S. patents, another U.S. Patent, namely 4,277,344, discloses an interfacial synthesized reverse osmosis membrane. This membrane is prepared from a cross-linked interfacially polymerized aromatic polyamine which has been prepared from an essentially monomeric polyacyl halide and an essentially monomeric arylene polyamine. The patent indicates that the acyl halide which is employed as one of the components in the interfacial polymerization reaction should be free of interfering substituents. The patent refers to these substituents as moieties which are capable of interfering with intermolecular amine- carboxylic acid, amide-forming condensation reactions and points out that such interference is generally steric and/or chemically reactive. An example of steric interference or steric hindrance would be the location of a substituent other than hydrogen on a ring position adjacent to an amine group on the polyamine reactant. An example of chemical interference would be the location of an acyl halide reactive substituent on the polyacyl halide or an amine-reactive substituent on the polyamine. The patent further states that such chemical interfering substituents would lead to the formation of internal esters, internal amides, internal salts, or the like, or another possible consequence which would be attendant upon the performance of these moieties would be an unpredictable effect on cross-linked densities.
This patent also states that substituents on the aromatic nucleus other than the amine groups themselves are likely to detract from the performance of the ultimately obtained polymer, even the substituents which are as small as the methyl group, possibly having undesirable effects particularly when substituted on a ring position adjacent to the primary amine group. Thus, it is apparent that this patent teaches away from the presence of substituents on the aromatic ring of the polyamine to prepare a membrane such as that which is
obtained when utilizing the components of the present invention.
In addition, the polymerized aromatic polyamine of this patent which may be depicted as follows:
may undergo deliberate chlorination in which it is stated that the chlorination process properly removes unreacted aromatic polyamines to produce a compound depicted as follows:
This deliberate chlorination of the membrane is required in order to improve the performance of said membrane in subsequent desalination operations. The patent also states that when the membrane of the reference was not fabricated under optimum amine and acyl halide concentrations, the salt rejection, even after the deliberate chlorination treatment, ranged from 88 to 97% and that even this loss of salt rejection capability can be minimized or avoided through modification of the polyamine; e.g., by acylation, alkylation, aldehyde condensation and other reactions which replace the amide hydrogen atoms with cross-links or other functional groups besides hydrogen. The focus of the patent therefore is on the modification of the amide portion of the membrane which is in contradistinction to the modification of the aromatic portion of the membrane
which is produced according to the present invention. This modification of the aromatic portion of the membrane may be illustrated by the following formula:
In this formula, it is to be noted that the chlorine substituent is on the aromatic ring portion of the polyamine, the dotted lines connecting the chlorine substituent to the ring indicating that the chlorine may be either in the 4 or 5 position depending upon the particular compound which has been chosen as one of the components of the desired membrane.
Another Patent, No. 3,948,823, discloses the preparation of membranes from blends of preformed polymers. These membranes comprise a vastly different concept from the membranes of the present invention which are prepared by an interfacial condensation polymerization of reactive monomers on the surface of an inert support polymer. The polymers which are taught by this reference are not soluble in solvents which are compatible with the support polymers utilized in the present invention. Therefore, an attempt to cast a solution of a polymer as taught by this patent on the surface of a support polymer which is utilized in the present invention would result in the dissolution of the support polymer rather than in the formation of a composite membrane which is the present invention.
In contradistinction to what has been taught in the prior patents and this specification, we have now discovered that semipermeable membranes which possess the desirable characteristics of high salt rejection, good flux and high resistance to chlorine may be prepared in
an interfacial polymerization reaction utilizing an aromatic polycarboxylic acid chloride and an aromatic polyamine in which the chlorine may be situated on a carbon atom adjacent to a primary amine group as the reactive components.
SUMMARY OF THE INVENTION
This invention relates to reverse osmosis membranes. More specifically, the invention is concerned with reverse osmosis membranes which exhibit an extreme resistance to chlorine degradation.
As was previously discussed, the use of reverse osmosis membranes for the separation of liquid from liquid or solids from liquids are important articles of commerce. This is especially true in the area of desalination whereby water which is brackish or saline in nature may be rendered potable or suitable for use in other industrial or agricultural regions by passing the water through reverse osmosis membranes. The particular membranes which constitute the inventive feature of the present application will comprise the reaction product resulting from the reaction of a aromatic polyamine and an aromatic polycarboxylic acid chloride, said membrane being composited or coated on a porous support backing material. By utilizing these membranes in a desalination process, it is possible to treat a saline or brackish water source over a relatively long period of time without replacement of the membrane, the long life of the membrane being, in part, due to the resistance to degradation resulting from exposure to chlorine in the water source.
It is therefore an object of this invention to provide a reverse osmosis membrane, suitable for use in separation processes, which possesses desirable characteristics.
A further object of this invention is to provide a process for preparing a semipermeable membrane which is resistant to chlorine, thus rendering the membrane suitable for use in separation processes such as desalination of water where chlorine is present in an amount sufficient to degrade other types of membranes.
In one aspect an embodiment of this invention resides in a chlorine-resistant semipermeable membrane comprising a porous support backing material having supported thereon an interfacial polymerized condensation reaction product formed by the process of reacting together an aromatic polyamine containing a chlorine substituent on the aromatic ring and an aromatic polycarboxylic acid chloride. Another embodiment of this invention resides in a process for the preparation of a chlorine-resistant semipermeable membrane which comprises casting a solution of an aromatic polyamine containing a chlorine substituent on the aromatic ring on a porous support backing material, removing excess solution, contacting said coated support material with an organic solvent solution of an aromatic polycarboxylic acid chloride to form an interfacial condensation reaction product membrane on the surface of said porous backing material, curing the resultant composite at curing conditions, and recovering the resultant chlorine-resistant semipermeable membrane.
A specific embodiment of this invention is found in a chlorine-resistant semipermeable membrane comprising polysulfone having supported thereon the interfacial polymerized condensation reaction product resulting from the reaction of 4-chloro-m- phenylenediamine or 5-chloro-m-phenylenediamine with trimesoyl chloride. Another specific embodiment of this invention resides in a process for the preparation of a chlorine- resistant semipermeable membrane which comprises casting an aqueous solution of 4-chloro-m-phenylenediamine or 5-
chloro-m-phenylenediamine on a porous backing support material comprising polysulfone, removing excess solution, contacting said coated polysulfone with a hexane solution of trimesoyl chloride to form an interfacial polymerized condensation reaction product membrane on the surface of said polysulfone, curing the resultant composite at a temperature in the range of from about 25° to about 150°C for a period of time in the range of from about 10 minutes to about two hours, and recovering the resultant chlorine-resistant semipermeable membrane.
DETAILED DESCRIPTION OF THE INVENTION
As hereinbefore set forth, the present invention is concerned with semipermeable membranes which are resistant to chlorine. The membranes are prepared by casting an aqueous solution of an aromatic polyamine which contains a chlorine substituent on the aromatic ring of the compound on a porous backing support material, removing excess solution, and thereafter contacting the coated support material with an organic solvent solution of an aromatic polycarboxylic acid chloride. The organic solvent which is used to prepare the solution of the aromatic polycarboxylic acid chloride is immiscible with the aqueous solution, thus permitting the formation of an interfacial polymerized condensation reaction product on the surface of.the support material. The resulting composite is then cured to provide a semipermeable membrane which exhibits favorable characteristics with respect to salt rejection and flux as well as resistance to chlorine.
As was previously discussed, the production of such a membrane which possesses these desirable characteristics was totally unexpected in view of the prior references which have indicated that it was highly unlikely that a compound such as an aromatic polyamine
which contains a substituent on the aromatic ring in a position ortho to an amine group will result in the formation of a suitable polymeric membrane. It was heretofore believed that this interfering substituent on the aromatic ring in the ortho position was said to be detrimental even if the size of the substituent was as small as a methyl group and that said group would be likely to detract from the performance of a resulting polymer. In contradistinction to the thoughts of prior researchers, we have now discovered that the presence of a chlorine moiety as a substituent on the aromatic ring of an aromatic polyamine which is substantially similar in size to a methyl moiety, is not detrimental to the formation of a suitable membrane. As will hereinafter be shown in the examples at the end of the specification, the membrane of the present invention which is formed from the interfacial polymerization of an aromatic polyamine containing a chlorine substituent on the aromatic ring in a position either ortho or meta to an amine substituent and an aromatic polycarboxylic acid chloride will possess chlorine-resistant properties which are either equal to or superior to other membranes which are not formed from the reaction of these two components and which will exhibit a resistance to chlorine. In addition, the membranes of the present invention will not require further modification or treatment, such as that taught in a prior patent, to enhance the desired properties of the membrane.
The aromatic polyamines containing a chlorine substituent on the aromatic ring which comprise one component of the product of the present invention will comprise either 4-chloro-m-phenylenediamine or 5-chloro- m-phenylenediamine. It is also contemplated within the scope of this invention that aromatic polyamines containing a chlorine substituent on the aromatic ring in which the amine moieties are in a position para to each other may also be employed, however not necessarily with equivalent results. The aromatic polycarboxylic acid
chloride which forms the other component necessary to form the interfacial polymerization product will comprise either di- or tricarboxyliσ acid chloride such as trimesoyl chloride (1,3,5-benzene tricarboxylic acid chloride) , isophthaloyl chloride, terephthaloyl chloride as well as mixtures of trimesoyl chloride and the isomeric phthaloyl chlorides.
In one embodiment, the chlorine-resistant semipermeable membranes of the present invention may be prepared by coating the porous support backing material with an aqueous solution of the aromatic polyamine containing a chlorine substituent on the aromatic ring. As was previously set forth, the porous support backing material comprises a polymeric material containing pore sizes which are sufficient to permit the passage of permeate therethrough but are not large enough so as to interfere with the bridging over of the resulting ultrathin reverse osmosis membrane. In the preferred embodiment of the invention the pore sizes of the porous support backing material will range from about 1 to about 1000 millimicrons inasmuch as pores which are larger than 1000 millimicrons will permit the ultrathin reverse osmosis membrane to sag into the pore, thus disrupting the flat sheet configuration which is a desirable characteristic of the membrane. Examples of porous support backing material which may be used to prepare the desired membrane composite will include such polymers as polysulfone, polycarbonate, microporous polypropylene, the various polyamides, polyphenylene ether, etc. The porous support backing material is coated with an aqueous solution of the aromatic amine containing a chlorine substituent on the aromatic ring utilizing either a hand casting or continuous operation. The solution which is utilized as the carrier for the aromatic amine containing a chlorine substituent on the aromatic ring will be 100% water or 100% acetonitrile or intermediate mixtures of water and acetonitrile. In the preferred embodiment of the invention, the aromatic amine
containing a chlorine substituent on the aromatic ring will be present in the solution in an amount in the range of from about 0.1 to about 5% by weight of the solution. In addition, it is also contemplated within the scope of this invention that the solution may also contain additional components which, while not entering into the reaction, provide additional assistance in formulating the desired interfacial polymerization reaction product. Examples of these additives which may be present will include surfactants including ionic surfactants such as sodium lauryl sulfate, lower molecular weight alcohols such as ethanol, ethanol, ethylene glycol, the isomeric propanols, butanols, or nonionic surfactants such as polyethylene glycol, polypropylene glycol, copolymers of ethylene glycol and propylene glycol, etc. In addition, the aqueous solution may also contain basic acid scavengers such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, etc.
After coating the porous support backing material with the solution of the aromatic amine containing a chlorine substituent on the aromatic ring, the excess solution is drained and the coated support material is then contacted with an organic solvent solution of the aromatic polycarboxylic acid chloride. Again, in the preferred embodiment of the invention, the aromatic polycarboxylic acid chloride is present in the organic solvent solution in a range of from about 0.1 to about 5% by weight of the solution. The organic solvents which are employed in the process of this invention will comprise paraffins such as β-pentane, n-hexane, n- heptane, cyclopentane, cyclohexane, methylcyclopentane, etc. or, a halogenated solvent such as trichlorotrifluoroethane.
Inasmuch as the organic solvent and the solvent for the aromatic amine containing a chlorine substituent on the aromatic ring are substantially immiscible or incompatible, the polymerization of the two components of the membrane will occur substantially only at the
interface between the solvent phases and thus an interfacially polymerized reaction product comprising a thin film membrane will be formed thereat. The contact time required for the formation of the thin film membrane will fluctuate over a relatively wide range of from about 1 second to about 60 seconds. Following the formation of the interfacially polymerized reaction product on the surface of the porous support backing material, the resultant composite may be cured to remove any remaining solvent and firmly affix the thin film membrane on the surface of the support. The curing of the composite membrane may be effected over a wide temperature range, said temperature being from ambient (20°-25°C) up to about 150°C for a period of time ranging from about 1 minute to about 2 hours or more in duration. The operating parameters of time and temperature will be interdependent, the primary criteria for the curing of the membrane being that said curing time is sufficient to provide the desired membrane but being insufficient to affect the desired characteristics of the thin film membrane and the porous backing support material. For example, excessive heat or curing time may affect the pore size of the backing material, thus resulting in a decrease of the desired flux rate of the membrane. It is also contemplated within the scope of this invention that the chlorine-resistant semipermeable membrane may be prepared in a continuous manner of operation. When this type of operation is employed, a porous support backing material of the type hereinbefore set forth in greater detail is continuously passed through a bath of an aqueous solution of the aromatic polyamine containing a chlorine substituent on the aromatic ring, said solution also containing, if so desired, a surfactant and an acid scavenger. After passage through the bath, the backing material is continuously withdrawn and, if so desired, passed between rollers in order to remove any excess solution which may be present. The coated support material is then also
continuously passed through the solution of the aromatic polycarboxylic acid chloride in an organic solvent. The interfacial polymerization reaction will occur during the contact time between the solutions following which the composite comprising the interfacial polymerized reaction product in the form of a thin film semipermeable membrane on the porous support backing material will then be cured as, for example, by passage through an oven which is maintained at a desired curing temperature, the passage through said oven being at a predetermined rate so as to avoid any possible damage to the composite membrane.
The resultant chlorine-resistant semipermeable membrane may then be employed for the separation process desired such as the desalination of sea water or brackish water, other treatments of water such as softening of hard water whereby salts are removed, boiling said water treatment, concentration of whey, etc. The membranes which are in the form of flat sheets are particularly applicable for use in modules either in single sheet or multiple sheet units whereby the sheet or sheets are wound in a spiral type configuration.
The following examples are given for purposes of illustrating the novel chlorine-resistant semipermeable membranes and to their use thereof as separation agents. However, it is to be understood that these examples are provided merely for purposes of illustration and that the present invention is not necessarily limited thereto.
EXAMPLE I:
A chlorine-resistant semipermeable membrane was prepared by handcasting a solution comprising 1.0% by weight of 4-chloro-js-phenylenediamine in a solvent comprising 97% of a 50/50 mixture of acetonitrile and water and 3% isopropanol on a 8" by 10" sheet of polysulfone at ambient temperature and pressure. The
excess solution was drained after a period of 30 seconds, and the coated polysulfone contacted with a solution comprising 0.5% by weight of trimesoyl chloride in a hexane solvent. After a period of 30 seconds, the excess organic solvent was drained and the resultant semipermeable membrane composite was washed with water. Following this, the membrane composite, which may be designated as a poly(chlorophenylenediamine trimesamide) , was then cured at a temperature of 70°C for a period of 30 minutes.
A sample of the membrane prepared according to the above paragraph in a size of 1" x 3" was placed in a cell and a synthetic sea water feed containing 5000 ppm of sodium chloride was passed across the surface of the membrane at a feed flow rate of 1.3 gal/min (GPM) . The test conditions which were employed during the experiment included a pressure of 800 pounds per square inch (psi) on one side of the membrane while the other side of the membrane was maintained at atmospheric pressure. A temperature of 25°C was maintained throughout the experiment while keeping the pH of the feed at 5.5. The permeate which was collected from the flowthrough was measured and it was found that there was a 93.5% rejection of sodium chloride at a flux rate of 8.6 GFD.
EXAMPLE II:
A membrane was prepared in a manner similar to that set forth in Example I above by contacting an 8" x 10" sheet of polysulfone with a solution comprising 2.0% by weight of 4-chloro-m-phenylenediamine in a 97% water and 3% isopropanol solvent at ambient temperature and pressure for a period of 30 seconds. The excess solution was drained and the coated polysulfone support was contacted with an organic solution comprising 0.25% by weight of trimesoyl chloride in hexane. After allowing a contact period of 30 seconds, the resulting membrane
composite was washed with water and dried at a temperature of 70°C for a period of 30 minutes.
As in the previous example, a 1" x 3" sample of the membrane prepared according to the above paragraph was placed in a cell and subjected to a feed similar in nature to that set forth in Example I above under conditions which were also similar in nature. Analysis of the permeate recovered from this experiment disclosed that there had been a 94% rejection of sodium chloride at a flux rate of 12.8 GFD.
When the above experiment was repeated by treating the polysulfone support with a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate, and 1.0% by weight of 4-chloro-m- phenylenediamine followed by contact with an organic solution comprising 0.25% by weight of trimesoyl chloride in hexane, the resulting membrane composite showed a 93.7% rejection of sodium chloride at a flux rate of 9.3 GFD.
EXAMPLE III;
In this example, a membrane composite was prepared by coating an 8" x 10" sheet of polysulfone with a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate, and 1.0% by weight of 5-chloro-m- phenylenedia ine at ambient temperature and pressure for a period of 30 seconds, and then draining. The coated polysulfone was then contacted with an organic solution comprising 1.0% by weight of trimesoyl chloride in hexane, the contact being effected at ambient temperature and pressure for a period of 30 seconds. The resulting thin film interfacial polymerized condensation reaction product semipermeable membrane composited on polysulfone was then cured at a temperature of 70°C for a period of 30 minutes.
As in the preceding examples, a 1" x 3" sample of the thus prepared membrane was placed in a cell and subjected to a synthetic sea water feed containing 5000
ppm of sodium chloride. A charge to the surface of the membrane was effected at a pressure of 800 psi while maintaining the temperature at 25°C and the pH of the feed at 5.5. Analysis of the permeate disclosed a 97.2% sodium chloride rejection at a flux rate of 19.6 GFD. A membrane similar in nature to that prepared in the first paragraph of this example was prepared using a similar technique. However, the organic solution which was employed to effect the interfacial polymerization on the surface of the polysulfone contained only 0.5% by weight of trimesoyl chloride. The membrane, when subjected to the action of a synthetic sea water feed under conditions similar to that hereinbefore set forth gave a 97.8% sodium chloride rejection at a flux of 22.5 GFD. Another sample of this membrane, when subjected to the action of a synthetic sea water feed comprising 35,000 ppm of sodium chloride, under similar conditions to those hereinbefore set forth, gave a 97.4% sodium chloride rejection at a flux rate of 10.9 GFD. A similar membrane which was prepared utilizing only 0.25% by weight of trimesoyl chloride in hexane gave a 97.4% rejection of sodium chloride at a flux rate of 16.6 GFD.
EXAMPLE IV:
In this example, a series of membranes were prepared by coating a polysulfone support with a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate, and 1.0% by weight of 5-chloro-m- phenylenediamine for a period of 30 seconds. After draining the excess solution from the coated support, it was then contacted with an organic solution containing 0.1% by weight of trimesoyl chloride in hexane. After a contact time of 30 seconds had elapsed, the excess solution was removed and the membrane was cured in an oven at a temperature of 70°C for a period of 30 minutes. Samples of each of the membranes thus prepared were subjected to the action of a feed comprising a synthetic
sea water containing 5000 ppm of sodium chloride. The charge to the cell containing the membrane was effected at a pressure of 800 psi while maintaining a temperature of 25°C. Analysis of the permeate showed sodium chloride rejections of 97.6% and 99.0% at fluxes of 13.7 and 14.7 GFD respectively.
When the above experiments were repeated by treating polysulfone supports with solutions comprising 1.0% by weight of 5-chloro-m-phenylenediamine in a 97% water and 3% ethanol solvent followed by contact with organic solutions comprising 0.1% by weight of trimesoyl chloride in hexane, the resulting membranes showed sodium chloride rejections of 98.4% and 98.8% at fluxes of 11.2 and 18.4 GFD respectively.
EXAMPLE V:
In this example, a membrane composite was prepared by coating an 8" x 10" sheet of polysulfone with a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate and 1.0% by weight of 5-chloro-m- phenylenediamine at ambient temperature and pressure. Contact was maintained for a period of 30 seconds, then the excess aqueous solution was drained. The coated polysulfone was then contacted with an organic solution comprising 0.45% by weight of trimesoyl chloride and 0.05% by weight of isophthaloyl chloride in hexane, the contact being effected at ambient temperature and pressure for a period of 30 seconds. The excess organic solution was removed by draining, and the resulting thin film interfacial polymerized condensation reaction product semipermeable membrane composited on polysulfone was then cured at a temperature of 70°C for a period of 30 minutes.
As in preceding examples, a 1" x 3" sample of the thus prepared membrane was placed in a cell and subjected to a synthetic sea water feed containing 5000 ppm of sodium chloride. A charge to the surface of the membrane was effected at a pressure of 800 psi while
maintaining the temperature at 25°C and the pH of the feed at 5.5. Analysis of the permeate disclosed a 93.4% rejection of sodium chloride at a flux rate of 24.3 GFD.
EXAMPLE VI:
To illustrate the efficacy of a mixture of aromatic amines containing a chlorine substituent on the aromatic ring, a membrane composite was prepared by coating an 8" x 10" sheet of polysulfone with a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate, 0.50% by weight of 5-chloro-m- phenylenediamine, and 0.50% by weight of 4-chloro-m- phenylenediamine at ambient temperature and pressure. Contact was maintained for a period of 30 seconds, then the excess aqueous solution was drained. The coated polysulfone was then contacted with an organic solution comprising 0.5% by weight of trimesoyl chloride in hexane, the contact being effected at ambient temperature and pressure for a period of 30 seconds. The excess organic solution was removed by draining, and the resulting membrane composite was then cured at a temperature of 70°C for a period of 30 minutes.
The membrane, when subjected to the action of a synthetic sea water feed under conditions similar to that hereinbefore set forth gave a 77.9% sodium chloride rejection at a flux rate of 11.96 GFD.
EXAMPLE VII:
In this example, a membrane composite was prepared by coating an 8" x 10" sheet of polysulfone with a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate, 0.50% by weight of 5-chloro-m- phenylenediamine, and 0.50% by weight of 4-chloro-m- phenylenediamine at ambient temperature and pressure. Contact was maintained for a period of 30 seconds, after which the excess aqueous solution was removed by draining. The coated polysulfone was then contacted with an organic solution comprising 0.45% by weight of
trimesoyl chloride and 0.05% by weight of isophthaloyl chloride in hexane, the contact being effected at ambient temperature and pressure for a period of 30 seconds. The excess organic solution was removed by draining, and the resulting membrane composite thus produced was then cured at a temperature of 70°C for a period of 30 minutes.
As in preceding examples, a 1" x 3" sample of the composite membrane was placed in a cell and subjected to a synthetic sea water feed containing 5000 ppm of sodium chloride. A charge to the surface of the membrane was effected at a pressure of 800 psi while maintaining the temperature at 25°C and the pH of the feed at 5.5. Analysis of the permeate showed a sodium chloride rejection of 70.9% at a flux rate of 18.6 GFD.
EXAMPLE VIII:
As a further example, a membrane was prepared using a continuous casting technique. The process was effected by continuously passing a sheet of polysulfone through a bath of 1.0% by weight of 4-chloro-m- phenylenediamine in a 50/50% solution of acetonitrile and water which contained 0.02% by weight of a surfactant comprising sodium lauryl sulfate. The rate of passage of the polysulfone sheet through the bath was effected at a speed of 0.33 feet per minute at atmospheric pressure and ambient temperature. The contact of the polysulfone sheet with the water-acetonitrile solution lasted for a period of 20 seconds. The sheet of coated polysulfone was continuously withdrawn and the excess aqueous solution was drained therefrom. Following this, the sheet was continuously passed through a bath of hexane which contained 1.0% by weight of trimesoyl chloride. The contact of the coated polysulfone sheet with the organic solution lasted for a period of 20 seconds. Thereafter the thin film semipermeable membrane composited on the surface of the polysulfone was recovered and subjected to a curing step in an oven at a temperature of 80°C for a period of 30 minutes.
A 1" x 3" sample of the thus prepared membrane was placed in a cell and a feedstock comprising a synthetic sea water feed which contained 5000 ppm of sodium chloride was passed over the surface of the membrane at a temperature of 25°C and at a pressure of 800 psi on one side of the membrane, the other side of the membrane being maintained at atmospheric pressure. The permeate was analyzed and it was found that there had been a 97.9% rejection of the sodium chloride at a flux rate of 4.6 GFD.
A similar membrane which was prepared from a 100% aqueous solution containing 0.025% by weight of sodium lauryl sulfate, and 1.0% by weight of 4-chloro-m- phenylenediamine which was contacted with an organic solution of hexane containing 1.0% by weight of trimesoyl chloride resulted in a membrane which, after having been cured at a temperature of 70°C for a period of 45 minutes, gave a rejection of 97.1% of sodium chloride at a flux rate of 8.3 GFD.
EXAMPLE IX:
In this example, a membrane was prepared by continuously passing a polysulfone sheet through a bath which comprised 2.0% by weight of 4-chloro-m- phenylenediamine in a solvent of a 50/50 mixture of acetonitrile and water at ambient temperature and pressure, the passage of the polysulfone sheet through the bath being effected at a rate of 0.33 ft./min. with a contact time of 20 seconds. The polysulfone sheet was continuously withdrawn from the bath and after excess solution had been drained, it was continuously charged to a hexane solution which contained 0.84% by weight of trimesoyl chloride and 0.16% by weight of isophthaloyl chloride. After a contact time of 20 seconds had been effected, the membrane composite was withdrawn and cured at a temperature of 70°C for a period of 30 minutes. A 1" x 3" sample of the membrane prepared according to the above paragraph was subjected to a
desalination reaction in a manner similar to that hereinbefore set forth utilizing a synthetic sea water feed containing 5000 ppm of sodium chloride. The feed was passed over the surface of the membrane at a rate of 1.3 GPM at a pressure of 800 psi and a temperature of 25°C. Analysis of the permeate which was recovered showed that there had been an 83.7% rejection of the sodium chloride at a flux rate of 4.7 GFD.
EXAMPLE X:
As a further example, a membrane was prepared using a continuous casting technique. The process was effected by continuously passing a sheet of polysulfone through a bath of 0.6% by weight of 5-chloro-m- phenylenediamine in water which contained 20 ppm of a surfactant comprising sodium lauryl sulfate. The rate of passage of the polysulfone sheet through the bath was effected at a speed of 2.0 feet per minute at atmospheric pressure and ambient temperature. The contact time of the polysulfone sheet with the aqueous solution lasted for a period of 9 seconds. The sheet of coated polysulfone was continuously withdrawn and the excess aqueous solution was drained therefrom. Following this, the sheet was continuously passed through a bath of hexane which contained 0.5% by weight of trimesoyl chloride. The contact of the coated polysulfone sheet with the organic solution lasted for a period of 9 seconds. Thereafter, the thin film semipermeable membrane composited on the surface of the polysulfone was recovered and subjected to a curing step in an oven at a temperature of 72° ± 2°C.
A 1" x 3" sample of the thus prepared membrane was placed in a cell and a feedstock comprising a synthetic sea water feed which contained 5000 ppm of sodium chloride was passed over the surface of the membrane at a temperature of 25°C, a pH of 5.5, and at a pressure of 800 psi applied on one side of the membrane, the other side of the membrane being maintained at
atmospheric pressure. The feed flow rate was 1.3 GPM. The permeate was analyzed and it was found that there had been a 99.14% rejection of the sodium chloride at a flux rate of 8.1 GFD.
EXAMPLE XI:
In this example, a membrane composite was prepared by a method similar to that taught in U.S. Patent 4,277,344. An 8" x 10" sheet of polysulfone was coated with an aqueous solution containing 1.0% by weight of m-phenylenediamine at ambient temperature and pressure for a period of 30 seconds. After draining the excess aqueous solution, the coated polysulfone was then contacted with an organic solution comprising 0.5% by weight of trimesoyl chloride in hexane, the contact being effected at ambient temperature and pressure for a period of 30 seconds. The resulting thin film interfacial polymerized condensation reaction product semipermeable membrane composited on polysulfone was then cured at a temperature of 70°C for a period of 30 minutes, and was then evaluated as described in Example XII.
EXAMPLE XII:
The effects of hypochlorite on the performances of composite membranes prepared in Examples VIII and XI were compared.
As in preceding examples, a 1" x 3" sample of each composite membrane was placed in a cell and subjected to a synthetic sea water feed containing 5000 ppm of sodium chloride at a feed flow rate of 1.3 GPM. A charge to the surface of the membrane was effected at a pressure of 800 psi while maintaining the temperature at 25°C and the pH of the feed at 5.5. After 1 hour under these test conditions, the permeate from each cell was analyzed.
Without removing the samples from the cells, hypochlorite was added to the above synthetic sea water feed to give an effective sodium hypochlorite
concentration of 4 ppm. The membrane samples in the cells were then subjected to this hypochlorite containing feed under the same operating conditions described above. After 2 hours under these test conditions, the permeate from each cell was analyzed.
The membrane sample prepared according to Example VIII from 4-chloro-m-phenylenediamine and trimesoyl chloride showed increases in both sodium chloride rejection and flux rate, while the membrane sample prepared according to Example XI from m- phenylenediamine and trimesoyl chloride showed a smaller increase in sodium chloride rejection and a decrease in flux rate:
Membrane Without Hypochlorite With Hy
Sample Rejection f%) Flux (GFD) Rejection (
Ex. VIII 82 7.8 88
Ex. XI 94 22. 1 95. 2
<*>
EXAMPLE XIII:
To demonstrate the effect of long term hypochlorite exposure on the performance of a composite membrane sample prepared in Example IV from 5-chloro-m- phenylenediamine in a solvent comprising 97% of water and 3% of ethanol, and trimesoyl chloride in hexane, the following experiment was performed.
As in previous examples, a 1" x 3" sample of the thus prepared composite membrane was placed in a cell and subjected to a synthetic sea water feed containing 2000 ppm of sodium chloride at a feed flow rate of 1.3 GPM. A charge to the surface of the membrane was effected at a pressure of 420 psi while maintaining the temperature at 25°C and the pH of the feed at 5.7 to 5.9. Hypochlorite was introduced into the feed periodically as described in Example XII, with a total accumulated exposure of 1360 ppm-hours. The permeate from the cell was periodically analyzed for sodium chloride rejection and flux rate. Although flux rate was depressed during the hypochlorite exposure, it was restored after exposure to hypochlorite-free feed. Sodium chloride rejection exhibited a modest improvement after this treatment:
EXAMPLE XIII DATA TABLE
Elapsed Avg. Hypochlorite Cumulative Hypochlorite Rejection Flux Time (hrs.) Cone, (ppm) Exposure (ppm - hrs) (%) (GFD)
0-20 97.4 5.8
20-108 6.0 530
108-138 530 97.6 3.5 t σ*>
138-228 9.2 1360 97.3 3.5
228-304 1360 98.3 5.5
EXAMPLE XIV:
To illustrate the fact that membranes could be prepared from a phenylenediamine containing a chlorine substituent on the aromatic ring which would be comparable in nature to those which did not contain a substituent on the aromatic ring of the phenylenediamine contrary to teachings of U. S. Patent 4,277,344, a series of membranes were prepared according to the teachings of this patent and compared to membranes which were prepared according to the process of the present invention. The membranes of the present invention and those of the U. S. Patent were subjected to a soak treatment of 1 ppm of hypochlorite for a period of 1 hour and a period of 16 hours. Following this, the membranes were subjected to a reverse osmosis treatment in a manner similar to that set forth in the above examples, the water feed containing 5000 ppm of sodium chloride at a feed flow rate of 1.3 GPM. The feed was charged to the surface of the membrane at a pressure of 800 psi while maintaining the temperature at 25°C and the pH of the feed at 5.5. The results of this test are set forth in the Table below. In this Table, the membranes labeled A, B, and C are those membranes prepared according to the teachings of U. S. Patent 4,277,344, and membranes D, E, and F are those which comprise the interfacial polymerized condensation reaction product of 5-chloro-m-phenylenediamine and trimesoyl chloride as described in Example IV of this application.
Membrane
B
It is readily apparent from a review of the above table that, contrary to the teachings of the patent, a membrane could be prepared from a phenylenediamine containing a chlorine substituent on the aromatic ring and trimesoyl chloride which is comparable in nature to the membrane of the patent and that, contrary to the teachings of the patent in Examples XV and XVI thereof, discloses that the membrane of the patent exhibits both decreased salt rejection and decreased flux.
Claims
1. A chlorine-resistant semipermeable membrane comprising a porous support backing material having supported thereon an interfacial polymerized condensation reaction product formed by the process of reacting together an aromatic polyamine containing a chlorine substituent on the aromatic ring and an aromatic polycarboxylic acid chloride.
2. The chlorine-resistant semipermeable membrane as set forth in Claim 1 in which said aromatic polyamine containing a chlorine substituent on the aromatic ring is at least one member of the group consisting of 4-chloro- m-phenylenediamine and 5-chloro-m-phenylenediamine.
3. The chlorine-resistant semipermeable membrane as set forth in Claim 1 in which said polycarboxylic acid chloride is at least one member of the group consisting of isophthaloyl chloride, terephthaloyl chloride, trimesoyl chloride and mixtures thereof.
4. The chlorine-resistant semipermeable membrane as set forth in Claim 1 in which said aromatic polyamine containing a chlorine substituent on the aromatic ring is present in said interfacial polymerized condensation reaction product in a weight ratio of from about 0.1:1 to about 40:1 of aromatic polyamine containing a chlorine substituent on the aromatic ring to aromatic polycarboxylic acid chloride.
5. A process for the preparation of a chlorine- resistant semipermeable membrane which comprises casting a solution of an aromatic polyamine containing a chlorine substituent on the aromatic ring on a porous support backing material, removing excess solution, contacting said coated support material with an organic solvent solution of an aromatic polycarboxylic acid chloride to form an interfacial condensation reaction product membrane on the surface of said porous backing material, curing the resultant composite at curing conditions, and recovering the resultant chlorine-resistant semipermeable membrane.
6. The process as set forth in Claim 5 in which said curing conditions include a temperature in the range of from about 25° to about 150°C for a period of time in the range of from about 10 minutes to about 2 hours.
7. The process as set forth in Claim 5 in which said aromatic polyamine containing a chlorine substituent on the aromatic ring is at least one member of the group consisting of 4-chloro-ffi-phenylenediamine and 5-chloro-m- phenylenediamine.
8. The process as set forth in Claim 5 in which said aromatic polycarboxylic acid chloride is at least one member of the group consisting of isophthaloyl chloride, terephthaloyl chloride, trimesoyl chloride and mixtures thereof.
9. The process as set forth in Claim 5 in which said aqueous solution of said aromatic polyamine containing a chlorine substituent on the aromatic ring may include an ionic or a nonionic surfactant.
10. The process as set forth in Claim 5 in which said aqueous solution of said aromatic polyamine containing a chlorine substituent on the aromatic ring may contain an organic solvent.
11. A process for the desalination of a saline water comprising contacting one side of the chlorine- resistant membrane of Claim 1 with said water and recovering as permeate desalinated water from the opposite side of said membrane.
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US06/898,074 US4772394A (en) | 1984-12-26 | 1986-08-20 | Chlorine-resistant semipermeable membranes |
KR1019900700807A KR900701377A (en) | 1988-09-14 | 1988-09-14 | Chlorine-resistant semipermeable membrane and its manufacturing method |
PCT/US1988/003171 WO1990002602A1 (en) | 1988-09-14 | 1988-09-14 | Chlorine-resistant semipermeable membranes |
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US8754139B2 (en) | 2009-02-20 | 2014-06-17 | International Business Machines Corporation | Polyamide membranes with fluoroalcohol functionality |
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USRE30351E (en) * | 1972-07-20 | 1980-07-29 | E. I. Du Pont De Nemours And Company | Aromatic polyimide, polyester and polyamide separation membranes |
GB2139113A (en) * | 1983-03-18 | 1984-11-07 | Culligan Int Co | Reverse osmosis membrane and method for the preparation thereof |
EP0211633A2 (en) * | 1985-08-05 | 1987-02-25 | Toray Industries, Inc. | Semipermeable composite membrane |
US4661254A (en) * | 1985-05-23 | 1987-04-28 | Uop Inc. | Chlorine-resistant semipermeable membranes |
EP0228248A2 (en) * | 1985-12-17 | 1987-07-08 | Nitto Denko Corporation | Composite semipermeable membranes |
US4772394A (en) * | 1984-12-26 | 1988-09-20 | Uop Inc. | Chlorine-resistant semipermeable membranes |
-
1988
- 1988-09-14 WO PCT/US1988/003171 patent/WO1990002602A1/en unknown
- 1988-09-14 KR KR1019900700807A patent/KR900701377A/en not_active Application Discontinuation
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
USRE30351E (en) * | 1972-07-20 | 1980-07-29 | E. I. Du Pont De Nemours And Company | Aromatic polyimide, polyester and polyamide separation membranes |
GB2139113A (en) * | 1983-03-18 | 1984-11-07 | Culligan Int Co | Reverse osmosis membrane and method for the preparation thereof |
US4772394A (en) * | 1984-12-26 | 1988-09-20 | Uop Inc. | Chlorine-resistant semipermeable membranes |
US4661254A (en) * | 1985-05-23 | 1987-04-28 | Uop Inc. | Chlorine-resistant semipermeable membranes |
EP0211633A2 (en) * | 1985-08-05 | 1987-02-25 | Toray Industries, Inc. | Semipermeable composite membrane |
EP0228248A2 (en) * | 1985-12-17 | 1987-07-08 | Nitto Denko Corporation | Composite semipermeable membranes |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8754139B2 (en) | 2009-02-20 | 2014-06-17 | International Business Machines Corporation | Polyamide membranes with fluoroalcohol functionality |
Also Published As
Publication number | Publication date |
---|---|
KR900701377A (en) | 1990-12-01 |
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