Patent US3580841A successfully refreshed from Google Patents.
US3580841A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ultrathin semipermeable membrane
Assignee: United States Department of the Interior
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Filing: 1969-07-31
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Granted: 1971-05-25
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Expires: 1989-07-31
Abstract
Abstract AN ULTRATHIN SEMIPERMEABLE REVERSE OSMOSIS MEMBRANE WHICH MAY BE MADE BY CASTING A CONCENTRATED POLYMER SOLUTION ON A LIQUID SURFACE AND THEN EVAPORATING, AND WHICH MAY BE LAMINATED WITH A SEPARATE POROUS SUPPORT MEMBRANE TO FORM A COMPOSITE REVERSE OSMOSIS MEMBRANE. A PROCESS OF SEPARATING SOLVENT FROM SOLUTION BY REVERSE OSMOSIS COMPRISING BRINGING THAT SOLUTION INTO CONTACT WITH A MEMBRANE COMPRISING A SEMIPERMEABLE ULTRATHIN MEMBRANE AT A PRESSURE ABOVE THE OSMOTIC PRESSURE.
Inventors
- 👤 John E Cadotte
- 👤 Peter S Francis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:07
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/08; B01D69/00; B01D69/12; B01D69/122; B01D71/12
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-05-24 | 1974-11-23 | 1975-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-24 | 1978-11-23 | 1979-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-24 | 1982-11-23 | 1983-05-25 | $7700.00 | Window Closed / Lapsed |