Process for making chromium-free orthorhombic sodium sulfate
US5520902A · kind A · utility
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20Claims
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Key dates
| Filing date | Nov 25, 1994 |
| Grant date | May 28, 1996 |
| Priority date | — |
| Expiry date | Nov 25, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S210/913
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Disclosed is a process for making orthorhombic Na.sub.2 SO.sub.4 containing less than 0.1 ppm chromium from a solution of Na.sub.2 SO.sub.4 containing 0.1 to 100 ppm Cr(III). The Cr(III) is oxidized to Cr(VI) at a pH greater than 7, water is evaporated from the solution to precipitate the orthorhombic Na.sub.2 SO.sub.4, and the precipitated orthorhombic Na.sub.2 SO.sub.4 is separated from the solution.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.