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US4367213A Expired / Lapsed US ⏱️ 0.0 years remaining

Use of selected catalyzed hydrazine compositions to reduce hexavalent chromium [Cr(VI)]

Assignee: Olin Corp
•
Filing: 1982-04-29
•
Granted: 1983-01-04
•
Expires: 2002-04-29
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Abstract

Abstract Disclosed is a process for reducing hexavalent chromium [Cr(VI)] in aqueous solutions to trivalent chromium [Cr(III)] by reacting a catalyzed hydrazine composition with the hexavalent chromium at a pH in the range from about 6.0 to about 8.0 to form an aqueous slurry of trivalent chromium compound, said catalyzed hydrazine composition comprising (a) a hydrazine compound, (b) at least 0.0005 parts by weight of a quinone compound per one part of hydrazine compound; and, preferably; (c) at least about 0.0005 parts by weight of an organometallic complex per part of hydrazine compound, said organometallic complex being the reaction product of: (i) a hydroxide selected from the group consisting of cobaltous hydroxide and manganous hydroxide; and (ii) at least one organic ligand selected from the group consisting of unsubstituted and substituted amino derivatives of carboxylic acids and salts thereof. The solid particles of trivalent chromium may then be separated from the aqueous solution by conventional means (e.g., filtration).

Inventors

  • 👤 Louis C. Fiorucci
  • 👤 Michael E. Johnson

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-31 05:54
CPC Classifications
C; C01; C01G; C01G37/00; B; B01; B01J; B01J31/00; B01J31/16; B01J31/22; B01J31/2204; B01J31/2208; B01J31/2226; B01J31/2243; B01J2231/00; B01J2231/60; B01J2531/00; B01J2531/80; B01J2531/84; B01J2531/845

Claims Analysis

Total Claims: 11
Claim 1
Independent Claim 75 words
A process for reducing hexavalent chromium [Cr(VI)] in aqueous solutions to trivalent chromium [Cr(III)] which comprises reacting a catalyzed hydrazine composition with said hexavalent chromium at a pH in the range from about 6.0 to about 8.0 to form an aqueous slurry of trivalent chromium compound [Cr(III)], said catalyzed hydrazine composition comprising (a) a hydrazine compound, and (b) at least 0.0005 parts by weight of a quinone compound per one part of said hydrazine compound.
Claim 2
Dependent Claim 75 words
A process for reducing hexavalent chromium [Cr(VI)] in aqueous solutions to trivalent chromium [Cr(III)] which comprises reacting a catalyzed hydrazine composition with said hexavalent chromium at a pH in the range from about 6.0 to about 8.0 to form an aqueous slurry of trivalent chromium compound [Cr(III)], said catalyzed hydrazine composition comprising (a) a hydrazine compound, and (b) at least 0.0005 parts by weight of a quinone compound per one part of said hydrazine compound.
Claim 3
Dependent Claim 17 words
The process of claim 1 wherein said formed trivalent chromium compound is separated from said aqueous solution.
Claim 4
Dependent Claim 11 words
The process of claim 1 wherein said hydrazine compound is hydrazine.
Claim 5
Dependent Claim 11 words
The process of claim 1 wherein said quinone compound is methylhydroquinone.
Claim 6
Dependent Claim 74 words
The process of claim 1 wherein said catalyzed hydrazine composition additionally contains at least about 0.0005 parts by weight of organometallic complex per part of said hydrazine compound, said organometallic complex being the reaction product of (i) a hydroxide selected from the group consisting of cobaltous hydroxide and manganous hydroxide; and (ii) at least one organic ligand selected from the group consisting of unsubstituted and substituted amino derivatives of carboxylic acids and salts thereof.
Claim 7
Dependent Claim 17 words
The process of claim 5 wherein said organic ligand is ethylenediamine tetraacetic acid (EDTA) and its salts.
Claim 8
Dependent Claim 30 words
The process of claim 1 wherein said aqueous solution contains from about 5 to about 1000 parts by weight of said hexavalent chromium per million parts of said aqueous solution.
Claim 9
Dependent Claim 23 words
The process of claim 1 wherein the molar ratio of hydrazine compound to said hexavalent chromium is from about 0.75:1 to about 20:1.
Claim 10
Dependent Claim 28 words
The process of claim 1 wherein said quinone compound is used in amounts from about 0.001 to about 0.1 parts by weight per one part of hydrazine compound.
Claim 11
Dependent Claim 29 words
The process of claim 5 wherein said organometallic complex is used in amounts from about 0.002 parts to about 0.1 parts by weight per one part of hydrazine compound.

References Cited (Backward Citations)

US4124500A Cited
US4026664A Cited
US4079018A Cited
US4086150A Cited
US4268486A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1986-01-03 1986-07-05 1987-01-04 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1990-01-03 1990-07-05 1991-01-04 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1994-01-03 1994-07-05 1995-01-04 $7700.00 Window Closed / Lapsed

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