Method to reduce hexavelant chromium in soils, sediments, industrial waste and other contaminated materials using ascorbic acid
US5951457A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 26, 1997 |
| Grant date | Sep 14, 1999 |
| Priority date | — |
| Expiry date | Jun 26, 2017 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA62D2101/43
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
The concentration of potentially toxic hexavalent chromium, {Cr(VI)}, in chromium-bearing soils/materials existing in the form of soils, sludges, sediments, fill, industrial wastes, or other materials is decreased by applying and mixing a single reducing agent, ascorbic acid, to effect chemical reduction of Cr(VI) to a less toxic valence state. Ascorbic acid is added at ambient temperature in aqueous solution or slurry form and mixed with Cr(VI)-bearing soils/materials in amounts based on test results of representative samples of the material to be treated. Ascorbic acid may also be added in a dry form if sufficient moisture is present in the soils/materials to allow for dissolution of the ascorbic acid and reaction with the Cr(VI) in the material. The percentage reduction of the Cr(VI) concentration is greater and is achieved more rapidly than previously reported using other organic chemical reducing agents. The process, which does not require modification of the pH of the Cr(VI)-bearing material, can be applied in situ to Cr(VI)-bearing materials, including unsaturated and/or saturated soils in the same soil column, using mixing equipment appropriate for the depth of soil or mate…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.