US3767572A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Destruction of edta by alkaline chlorination
Assignee: Individual
•
Filing: 1971-11-08
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Granted: 1973-10-23
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Expires: 1991-11-08
Abstract
Abstract Waste photographic processing solutions which contain ethylenediaminetetraacetate (hereinafter EDTA), such as exhausted ammonium iron EDTA bleaching or bleach-fixing solutions, are chlorinated to destroy EDTA and thereby increase the biodegradability of the solution. Chlorination can be effected by introduction of chlorine gas or by the use of hypochlorite solution. Since EDTA and complexes thereof account for a large portion of the oxygen consuming material present in photographic processing effluent, a significant source of water pollution is substantially eliminated by this method.
Inventors
- 👤 I Slovonsky
- 👤 T Bober
- 👤 T Dagon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 09:49
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/72; C02F1/76; Y; Y02; Y02W; Y02W10/00; Y02W10/30; Y02W10/37
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
21 words
The method of claim 1 wherein said chlorination is carried out with said solution at a pH of greater than 10.
Claim 2
Dependent Claim
22 words
The method as described in claim 1 wherein said chlorination is carried out with said solution at a pH of about 11.5.
Claim 3
Dependent Claim
18 words
The method described in claim 1 wherein said chlorination is effected by introducing chlorine gas into said solution.
Claim 4
Dependent Claim
19 words
The method as described in claim 1 wherein said chlorination is effected by mixing said solution with hypochlorite solution.
Claim 5
Independent Claim
72 words
A method for treating an exhausted ferric ammonium EDTA bleaching solution to precipitate iron therefrom and to reduce its oxygen demand so as to minimize water pollution resulting from disposal thereof, said method comprising the steps of a. introducing sodium hydroxide into said solution to precipitate iron hydroxide which can be separated and b. introducing a member selected from the group consisting of chlorine and hypochlorite into said solution to destroy EDTA.
Claim 6
Dependent Claim
14 words
The method of claim 6 wherein said steps (a) and (b) are performed simultaneously.
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) | 1976-10-22 | 1977-04-23 | 1977-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-22 | 1981-04-23 | 1981-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-22 | 1985-04-23 | 1985-10-23 | $7700.00 | Window Closed / Lapsed |