Zero discharge process for manufacturing of phosphorous acid and hypophosphorous acid
US5368832A · kind A · utility
1Cited by
6References
8Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 7, 1991 |
| Grant date | Nov 29, 1994 |
| Priority date | — |
| Expiry date | Jun 7, 2011 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B25/163
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Disclosed is a method of making phosphorous acid or hypophosphorous acid by reacting hydrogen chloride with a sodium phosphite or a sodium hypophosphite, respectively, in the presence of water to precipitate sodium chloride crystals and form the acid. The acid is separated from the sodium chloride crystals and can be passed through an anion exchange column that is preferably loaded with phosphite or hypophosphite ions, respectively, to remove residual chloride ions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.