US4772391A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Composite membrane for reverse osmosis
Assignee: United States Department of the Interior
•
Filing: 1986-06-24
•
Granted: 1988-09-20
•
Expires: 2006-06-24
Abstract
Abstract A composite lumen-side feed reverse osmosis membrane and its preparation are disclosed, the membrane comprising a polymeric microporous-walled hollow fiber support with an interfacially-polymerized ultrathin semipermeable salt-rejecting layer engrafted on the lumen or bore of the hollow fiber support, the support having walls that are substantially completely free of finger-like voids in excess of about 5 microns in the area of the wall adjacent the lumen. The preparation of the support comprises coaxially spin-casting (1) a fiber-forming solution containing a pore-forming material with (2) a lumen-forming fluid comprising from about 50 to about 70 vol % organic solvent in water.
Inventors
- 👤 Richard W. Baker
- 👤 Robert P. Barss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:29
CPC Classifications
B; B01; B01D; B01D69/00; B01D69/08; B01D69/12; B01D69/125; B01D69/1251
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
159 words
A method for making a reverse osmosis lumen-side feed composite membrane comprising the steps of: (a) forming a microporous-walled hollow fiber support with fiber walls that are microporous and substantially completely free of voids greater than about 5 microns in the area of the wall adjacent the lumen of said hollow fiber support by coaxially spin casting (1) a solution of a fiber-forming polymer selected from the group consisting of polysulfone, polyethersulfones, polyphenylsulfones, polyvinylidenefluorides, polyimides, and polyetherimides in an organic solvent, said fiber-forming polymer solution containing a nonpolymeric liquid pore-forming material selected from the group consisting essentially of water, monohydric alcohols containing from 1 to 4 carbon atoms, and mono-and dialkyl ethers of ethylene glycol, diethylene glycol and esters thereof, with (2) a lumen-forming fluid comprising from about 50 to about 75 vol % organic solvent in water; and (b) forming, by interfacial polymerization, a salt-rejecting semipermeable film on the inner lumen-defining surface of said microporous-walled hollow fiber support.
Claim 2
Independent Claim
159 words
A method for making a reverse osmosis lumen-side feed composite membrane comprising the steps of: (a) forming a microporous-walled hollow fiber support with fiber walls that are microporous and substantially completely free of voids greater than about 5 microns in the area of the wall adjacent the lumen of said hollow fiber support by coaxially spin casting (1) a solution of a fiber-forming polymer selected from the group consisting of polysulfone, polyethersulfones, polyphenylsulfones, polyvinylidenefluorides, polyimides, and polyetherimides in an organic solvent, said fiber-forming polymer solution containing a nonpolymeric liquid pore-forming material selected from the group consisting essentially of water, monohydric alcohols containing from 1 to 4 carbon atoms, and mono-and dialkyl ethers of ethylene glycol, diethylene glycol and esters thereof, with (2) a lumen-forming fluid comprising from about 50 to about 75 vol % organic solvent in water; and (b) forming, by interfacial polymerization, a salt-rejecting semipermeable film on the inner lumen-defining surface of said microporous-walled hollow fiber support.
Claim 3
Dependent Claim
33 words
The method of claim 1 wherein said organic solvent for said fiber-forming polymer and for said lumen-forming fluid is selected from the group consisting of dimethyl acetamide, dimethyl formamide, dimethyl sulfoxide and 1-methyl-2-pyrrolidinone.
Claim 4
Dependent Claim
23 words
The method of claim 1 wherein said pore-forming material is water in a concentration of from about 0.5 to about 5 wt %.
Claim 5
Dependent Claim
26 words
The method of claim 1 wherein said pore-forming material is ethylene glycol monomethyl ether in a concentration of from about 5 to about 30 wt %.
Claim 6
Dependent Claim
32 words
The method of claim 1 wherein said pore-forming material is a monohydric alcohol containing from 1 to 4 carbon atoms in a concentration of from about 5 to about 20 wt %.
Claim 7
Dependent Claim
24 words
The method of claim 1 wherein the concentration of said fiber-forming polymer in said solution is from about 18 to about 35 wt %.
Claim 8
Dependent Claim
34 words
The method of claim 4 wherein the concentration of said pore-forming material is about 20 wt % and said fiber-forming solution additionally contains about 1 wt % 2,4-diamino-6-phenyl-s-triazine and about 0.25 wt % polyvinylpyrrolidone.
Claim 9
Dependent Claim
34 words
The method of claim 5 wherein the concentration of said pore-forming material is about 10 wt % and said fiber-forming solution additionally contains about 1 wt % 2,4-diamino-6-phenyl-s-triazine and about 0.25 wt % polyvinylpyrrolidone.
Claim 10
Dependent Claim
23 words
The method of claim 4 wherein said fiber-forming polymer is polyetherimide and the concentration of said pore-forming material is about 10 wt %.
Claim 11
Dependent Claim
55 words
The method of claim 1 wherein said solution of fiber-forming polymer comprises about 27 wt % polysulfone in an organic solvent of dimethylacetamide containing about 20 wt % ethylene glycol monomethyl ether, about 1 wt % 2,4-diamino-6-phenyl-s-triazine, about 0.25 wt % water, and said lumen-forming fluid comprises about 72 vol % dimethyl acetamide in water.
Claim 12
Dependent Claim
51 words
The method of claim 1 wherein said solution of fiber-forming polymer comprises about 27 wt % polysulfone in an organic solvent of dimethylacetamide containing about 10 wt % N-propanol, 1 wt % 2,4-diamino6-phenyl-s-triazine, about 4.5 wt % water, and said lumen-forming fluid comprises about 62 vol % dimethyl acetamide in water.
Claim 13
Dependent Claim
11 words
The product of the method of claim 1, 10, or 11.
Claim 14
Dependent Claim
68 words
The method of claim 1 wherein said salt-rejecting semipermeable film is formed by the steps of: (a) forming a film of an aqueous solution of polyethyleneimine on the inner lumen-defining surface of said microporous-walled hollow fiber support; (b) contacting said film with a solution of a polyfunctional cross-linking reagent in a nonpolar organic solvent; and (c) heat curing to complete reaction between said polyethyleneimine and said cross-linking reagent.
Claim 15
Dependent Claim
12 words
The method of claim 13 wherein said cross-linking reagent is toluene diisocyanate.
Claim 16
Dependent Claim
12 words
The method of claim 13 wherein said cross-linking reagent is isophthaloyl chloride.
Claim 17
Dependent Claim
8 words
The product of the method of claim 13.
Claim 18
Dependent Claim
135 words
A composite hollow fiber membrane useful in reverse osmosis carried out by lumen-side feed comprising: (a) a microporous-walled hollow fiber support cast from a solution of a fiber-forming first polymer selected from the group consisting of polyethersulfones, polyphenylsulfones, polyvinylidenefluorides, polyimides and polyetherimides containing a nonpolymeric liquid pore-forming material selected from the group consisting essentially of water, monohydric alcohols containing from 1 to 4 carbon atoms, and mono- and dialkyl ethers of ethylene glycol, diethylene glycol and esters thereof, the walls of said support being substantially completely free of voids in excess of about 5 microns in the area of the wall adjacent the lumen of said hollow fiber support; and (b) a salt-rejecting semipermeable film of a second, different polymer on the inner lumen-defining surface of said support, said film being formed by interfacial polymerization.
Claim 19
Dependent Claim
135 words
A composite hollow fiber membrane useful in reverse osmosis carried out by lumen-side feed comprising: (a) a microporous-walled hollow fiber support cast from a solution of a fiber-forming first polymer selected from the group consisting of polyethersulfones, polyphenylsulfones, polyvinylidenefluorides, polyimides and polyetherimides containing a nonpolymeric liquid pore-forming material selected from the group consisting essentially of water, monohydric alcohols containing from 1 to 4 carbon atoms, and mono- and dialkyl ethers of ethylene glycol, diethylene glycol and esters thereof, the walls of said support being substantially completely free of voids in excess of about 5 microns in the area of the wall adjacent the lumen of said hollow fiber support; and (b) a salt-rejecting semipermeable film of a second, different polymer on the inner lumen-defining surface of said support, said film being formed by interfacial polymerization.
Claim 20
Dependent Claim
37 words
The membrane of claim 17 wherein the inner lumen-defining surface of said support has pores of less than 0.01 micron in diameter and said salt-rejecting semipermeable film has a thickness of from about 0.1 to 2.0 microns.
Claim 21
Dependent Claim
18 words
The membrane of claim 14 wherein said salt-rejecting semipermeable film is a copolymer of polyethyleneimine and toluene diisocyanate.
Claim 22
Dependent Claim
18 words
The membrane of claim 14 wherein said salt-rejecting semipermeable film is a copolymer of polyethyleneimine and isophthaloyl chloride.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-09-20 | 1992-03-21 | 1992-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-20 | 1996-03-21 | 1996-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-20 | 2000-03-21 | 2000-09-20 | $7700.00 | Window Closed / Lapsed |