IN270476: An improved extraction process for the removal of hexavalent chromium from waste solutions
Abstract
The invention relates to an extraction process for the quantitative removal of hexavalent chromium from waste solution containing Cr(VI). This invention particularly relates to the back extraction of chromium by a dilute NaOH solution for the removal and reuse of the chromate solution in a concentrated form from the acidic industrial waste solutions containing hexavalent chromium, by solvent extraction using tris 2-ethylhexyl amine (TEHA) mixed with 2% iso-decanol as phase modifier and diluted with distilled kerosene. This concentrated strip chromate solution can be used in electroplating bath or can be sold as a pure chromate salt. The invention utilizes very dilute solution of tris 2-ethylhexyl amine (TEHA) for the recovery of pure hexavalent chromium from industrial waste solutions containing Cr(VI), leaving all the impurities in the raffinate. The raffinate solution free from hexavalent chromium can be used as wash or rinse water in the process. The process not only meets the strict environmental regulations but also helps in the removal and reuse of Cr(VI) in a concentrated usable form from industrial waste solution.
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