US3656908A
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Method of determining the chromium content of aqueous mediums
Assignee: Veolia WTS USA Inc
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Filing: 1970-12-01
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Granted: 1972-04-18
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Expires: 1990-12-01
Abstract
Abstract Method of determining the chromium concentration in an aqueous medium containing either or both trivalent chromium or hexavalent chromium. The method generally entails acidifying the aqueous medium, oxidizing any trivalent chromium present in the aqueous medium to hexavalent chromium, and adding to the medium a composition comprising a water-soluble cobaltous salt and a chelating agent of the acetic acid derivative type. The color intensity of the resulting medium is then measured and compared to the intensity of samples of aqueous medium containing known quantities of chromate in its hexavalent state which have been treated in the same manner. One of the other features of the invention is the composition used in the method.
Inventors
- 👤 Charles A Noll
- 👤 Edward C Feddern
- 👤 Louis J Stefanelli
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:39
CPC Classifications
G; G01; G01N; G01N31/00; G01N31/22
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
28 words
A method according to claim 1 wherein the color intensity is ascertained by comparison with the color intensity of standard color solutions which respectively represent known chromate concentrations.
Claim 2
Dependent Claim
22 words
A method according to claim 1 wherein the aqueous medium is acidified to a pH of from about 1 to about 3.
Claim 3
Dependent Claim
37 words
A method according to claim 3 wherein said chelating agent is selected from the group consisting of 1,2-diaminocyclohexane tetra acetic acid, diethylenetriaminopenta acetic acid, ethylene diamine tetra acetic acid, nitrilotriacetic acid and the alkali metal salts thereof.
Claim 4
Dependent Claim
33 words
A method according to claim 4 wherein the aqueous medium is acidified by the addition of an acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.
Claim 5
Dependent Claim
26 words
A method according to claim 5 wherein said cobaltous compound is selected from the group consisting of cobaltous chloride, cobaltous sulfate, cobaltous nitrate, and cobaltous phosphate.
Claim 6
Independent Claim
109 words
A method for determining the concentration of trivalent chromium in an aqueous medium which comprises acidifying and adding a sufficient amount of a water-soluble ceric salt to said aqueous medium to at least oxidize the trivalent chromium of the aqueous medium to its hexavalent state, adding to said aqueous medium a composition comprising a water-soluble cobaltous salt and a water-soluble chelating agent selected from the group of acetic acid derivatives and the alkali metal salts thereof, wherein said composition contains at least 1 part by weight of said cobaltous compound for each 7 parts by weight of said chelating agent, and ascertaining the color intensity of the resulting solution.
Claim 7
Dependent Claim
28 words
A method according to claim 7 wherein the color intensity is ascertained by comparison with the color intensity of standard color solutions which respectively represent known chromate concentrations.
Claim 8
Dependent Claim
22 words
A method according to claim 7 wherein the aqueous medium is acidified to a pH of from about 1 to about 3.
Claim 9
Dependent Claim
37 words
A method according to claim 9 wherein said chelating agent is selected from the group consisting of 1,2-diaminocyclohexane tetra acetic acid, diethylenetriaminopenta acetic acid, ethylene diamine tetra acetic acid, nitrilotriacetic acid and the alkali metal salts thereof.
Claim 10
Dependent Claim
33 words
A method according to claim 10 wherein the aqueous medium is acidified by the addition of an acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.
Claim 11
Dependent Claim
26 words
A method according to claim 11 wherein said cobaltous compound is selected from the group consisting of cobaltous chloride, cobaltous sulfate, cobaltous nitrate, and cobaltous phosphate.
Claim 12
Independent Claim
99 words
A method of determining the total chromium concentration of an aqueous medium which comprises acidifying the aqueous medium to a pH of from about 1 to about 3, adding to said medium a water-soluble ceric salt to oxidize any Trivalent chromium present in the hexavalent state, adding to said medium a composition comprising at least 1 part by weight of a water-soluble cobaltous salt for about 7 parts by weight of a water-soluble chelating agent selected from the group consisting of acetic acid derivatives and the alkali metal salts thereof, and ascertaining the color intensity of the resulting solution.
Claim 13
Dependent Claim
112 words
A method according to claim 13 werein the color intensity is ascertained by comparison with the color intensity of standard color solutions which represent known chromate concentrations. 15) A method according to claim 13 wherein said aqueous medium is acidified with a mineral acid, said ceric salt is selected from the group consisting of ceric chloride, ceric sulfate, ceric phosphate and ceric nitrate, said cobaltous salt is selected from the group consisting of cobaltous chloride, cobaltous nitrate, cobaltous sulfate and cobaltous phosphate, and said chelating agent is selected from the group consisting of 1,2-diaminocyclohexane tetra acetic acid, diethylenetriaminopenta acetic acid, ethylenediamine tetra acetic acid, nitrilotriacetic acid and the alkali metal salts thereof.
Claim 14
Dependent Claim
53 words
A composition comprising at least one water-soluble cobaltous salt and a chelating agent selected from the group of acetic acid derivatives and the alkali metal salts thereof, wherein the composition contains from about at least 1 part by weight of said cobaltous compound for each 7 parts by weight of said chelating agent.
Claim 15
Dependent Claim
22 words
A composition according to claim 16 wherein the cobaltous compound is cobaltous chloride and the chelating agent is ethylenediamine tetra sodium acetate.
Claim 16
Dependent Claim
13 words
A composition according to claim 16 wherein the composition is an aqueous solution.
Claim 17
Dependent Claim
57 words
A composition according to claim 16 wherein said cobaltous salt is selected from the group consisting of cobaltous chloride, cobaltous sulfate, cobaltous nitrate, and cobaltous phosphate, and said chelating agent is selected from the group consisting of 1,2-diaminocyclohexane tetra acetic acid, diethylenetriaminopenta acetic acid, ethylene diamine tetra acetic acid, nitrilotriacetic acid and the alkali metal salts thereof.
Claim 18
Dependent Claim
13 words
A composition according to claim 19 wherein the composition is an aqueous solution.
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) | 1975-04-18 | 1975-10-18 | 1976-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-18 | 1979-10-18 | 1980-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-18 | 1983-10-18 | 1984-04-18 | $7700.00 | Window Closed / Lapsed |