US3642773A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Modified cellulose ester semipermeable membrane
Assignee: McDonnell Douglas Corp
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Filing: 1967-12-29
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Granted: 1972-02-15
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Expires: 1987-12-29
Abstract
Abstract CELLULOSE ESTER, ESPECIALLY CELLULOSE ACETATE, SEMIPERMEABLE MEMBRANES HAVING SUPERIOR PERMEATION PROPERTIES OF FLUX AND SOLUTE REJECTION WHICH ARE PARTICULARLY SUITED FOR DESALINATION OF AQUEOUS SALT SOLUTIONS BY REVERSE OSMOSIS, PRODUCED BY A METHOD WHICH INCLUDES PRE-TREATMENT OF THE CELLULOSE ESTER MATERIAL IN THE FORM OF AN AQUEOUS SLURRY WITH CATALYTIC AMOUNTS OF A STRONG ACID PRIOR TO CASTING THE CELLULOSE ESTER MATERIAL INTO A FILM. METHOD FOR PRODUCING THE ABOVE DESCRIBED MEMBRANE, AND METHOD FOR DESALINATION OF SALT WATER EMPLOYING THE ABOVE DESCRIBED MEMBRANE.
Inventors
- 👤 Fred E Littman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:14
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/08; B01D71/12; B01D71/14; B01D67/00; B01D67/0002; B01D67/0009; B01D67/0011; B01D67/00111; B01D71/76; B01D71/82
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) | 1975-02-14 | 1975-08-16 | 1976-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-14 | 1979-08-16 | 1980-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-14 | 1983-08-16 | 1984-02-15 | $7700.00 | Window Closed / Lapsed |