US3560232A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Modified cellulose ester semipermeable membrane and its method of manufacture
Assignee: McDonnell Douglas Corp
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Filing: 1967-12-29
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Granted: 1971-02-02
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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 PRETREATMENT OF THE CELLULOSE ESTER MATERIAL IN THE FORM OF AN INERT SOLVENT SOLUTION WITH CATALYTIC AMOUNTS OF A CONCENTRATED 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
2026-10-28 21:00
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/08; B01D71/12; B01D71/14; B01D67/00; B01D67/0002; B01D67/0009; 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) | 1974-02-01 | 1974-08-03 | 1975-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-01 | 1978-08-03 | 1979-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-01 | 1982-08-03 | 1983-02-02 | $7700.00 | Window Closed / Lapsed |