US4419242A
Expired / Lapsed
US
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Composite membrane for a membrane distillation system
Assignee: International Power Technology Inc
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Filing: 1982-02-18
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Granted: 1983-12-06
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Expires: 2002-02-18
Abstract
Abstract A composite membrane separates a distilland and a distillate, such as salt water and fresh water. The composite membrane comprises a thin lyophobic microporous layer or membrane and a thin lyophilic layer or membrane on both sides of the lyophobic membrane or on the distillate side. Evaporation and condensation takes place within the micropores of the lyophobic membrane. The lyophilic layer on the distilland side prevents intrusion of distilland into the pores of the lyophobic layer. The lyophilic layer on the distillate side changes the surface curvature of the liquid/vapor interface in a manner which enhances the distillation rate through the membrane.
Inventors
- 👤 Dah Y. Cheng
- 👤 Steve J. Wiersma
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 02:27
CPC Classifications
B; B01; B01D; B01D69/00; B01D69/12; B01D61/00; B01D61/36; B01D61/364; B32; B32B; B32B27/00; B32B27/06; B32B27/08; Y; Y10; Y10S; Y10S159/00; Y10S159/27
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
101 words
A composite membrane comprising: a microporous hydrophobic layer through which water can pass in the form of a vapor; a first hydrophilic layer on one surface of said microporous hydrophobic layer; said hydrophilic layer forming a barrier to prevent a salt bearing liquid from intruding with the pores of said hydrophobic layer; a second hydrophilic layer on the opposite surface of said hydrophobic layer; and said materials forming said second hydrophilic and said hydrophobic layers, and the pore sizes of said hydrophobic layer, being selected to prevent water-logging of said hydrophobic layer when there is a heat gradient across said membrane.
Claim 2
Dependent Claim
101 words
A composite membrane comprising: a microporous hydrophobic layer through which water can pass in the form of a vapor; a first hydrophilic layer on one surface of said microporous hydrophobic layer; said hydrophilic layer forming a barrier to prevent a salt bearing liquid from intruding with the pores of said hydrophobic layer; a second hydrophilic layer on the opposite surface of said hydrophobic layer; and said materials forming said second hydrophilic and said hydrophobic layers, and the pore sizes of said hydrophobic layer, being selected to prevent water-logging of said hydrophobic layer when there is a heat gradient across said membrane.
Claim 3
Dependent Claim
13 words
A composite membrane as in claim 1 wherein said hydrophilic layers are porous.
Claim 4
Dependent Claim
27 words
A composite membrane as in claim 2 wherein the average pore size of the hydrophilic layers is less than the average pore size of the hydrophobic layer.
Claim 5
Dependent Claim
20 words
A composite membrane as in claim 2 wherein the hydrophilic layer is a mixture of cellulose acetate and cellulose nitrate.
Claim 6
Dependent Claim
18 words
A composite membrane as in claim 2 wherein at least one of the hydrophilic layers is cellulose acetate.
Claim 7
Dependent Claim
16 words
A composite membrane as in claim 2 wherein at least one of hydrophilic layers is polysulfone.
Claim 8
Dependent Claim
17 words
A composite membrane as in claim 2 wherein at least one of the hydrophilic layers is polyallylamine.
Claim 9
Dependent Claim
21 words
A composite membrane as in claim 2 wherein the mean pore diameter of said hydrophilic layers is less than 0.5 m.
Claim 10
Dependent Claim
13 words
A composite membrane as in claim 1 wherein the hydrophobic layer is polytetrafluoro-ethylene.
Claim 11
Dependent Claim
14 words
A composite membrane as in claim 1 wherein the hydrophobic layer is polyvinylidene fluoride.
Claim 12
Dependent Claim
21 words
A composite membrane as in claim 1 wherein the mean pore diameter of the hydrophobic layer is less than 0.5 m.
Claim 13
Dependent Claim
13 words
A composite membrane as in claim 1 wherein said hydrophilic material is non-porous.
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) | 1986-12-05 | 1987-06-06 | 1987-12-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-05 | 1991-06-06 | 1991-12-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-05 | 1995-06-06 | 1995-12-06 | $7700.00 | Window Closed / Lapsed |