US4136025A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of cleaning membrane filter
Assignee: PPG Industries Inc
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Filing: 1977-08-18
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Granted: 1979-01-23
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Expires: 1997-08-18
Abstract
Abstract A method of cleaning a membrane such as an ultrafilter which has been used in the treatment of a cataphoretic paint containing lead is disclosed. The method involves treating the membrane with an aqueous solution of an acid which forms a water-soluble lead salt and a water-soluble organic solvent.
Inventors
- 👤 Robert R. Zwack
- 👤 Roger M. Christenson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:24
CPC Classifications
B; B01; B01D; B01D65/00; B01D65/02; B01D61/00; B01D61/14; B01D61/20; B01D2321/00; B01D2321/16; B01D2321/162
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
52 words
A method of cleaning a membrane which has been used for filtering under pressure a cataphoretic paint containing lead and which has been fouled by said paint, said method comprising: (A) treating said membrane with an aqueous solution of an acid which forms a water-soluble lead salt, and a water-soluble organic solvent.
Claim 2
Independent Claim
52 words
A method of cleaning a membrane which has been used for filtering under pressure a cataphoretic paint containing lead and which has been fouled by said paint, said method comprising: (A) treating said membrane with an aqueous solution of an acid which forms a water-soluble lead salt, and a water-soluble organic solvent.
Claim 3
Dependent Claim
12 words
The method of claim 1 in which the filtering is an ultrafiltration.
Claim 4
Dependent Claim
13 words
The method of claim 1 in which the acid is an organic acid.
Claim 5
Dependent Claim
26 words
The method of claim 3 in which the organic acid is selected from the class consisting of formic acid, lactic acid, acetic acid and citric acid.
Claim 6
Dependent Claim
17 words
The method of claim 1 in which the water-soluble solvent is a monoalkyl ether of ethylene glycol.
Claim 7
Dependent Claim
21 words
The method of claim 1 in which the cleaning solution is recirculated across the face of the fouled membrane under pressure.
Claim 8
Independent Claim
49 words
A method of cleaning a membrane which has been used for ultrafiltering a cataphoretic paint containing lead and which has been fouled by said paint, said method comprising: (A) circulating across the face of the membrane an aqueous solution of lactic acid and a monoalkyl ether of ethylene glycol.
Claim 9
Independent Claim
49 words
A method of cleaning a membrane which has been used for ultrafiltering a cataphoretic paint containing lead and which has been fouled by said paint, said method comprising: (A) circulating across the face of the membrane an aqueous solution of lactic acid and a monoalkyl ether of ethylene glycol.
References Cited (Backward Citations)
US3827976A
Cited
GB1453575A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-01-22 | 1982-07-24 | 1983-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-01-22 | 1986-07-24 | 1987-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-01-22 | 1990-07-24 | 1991-01-23 | $7700.00 | Window Closed / Lapsed |