Treatment of Waste Water from Chromium Plating by Solvent Extraction

Shibata Junji, Nishimura Sanji, Mukai Shigeru

doi:10.4144/rpsj1954.1975.57_34

In order to separate and recover chromium (VI) from waste water of chromium plating, the extraction of chromium (VI) with tri-n-butyl phosphate diluted in kerosene was investigated. The concentration of chromium (VI) in the feed aqueous phase was 130, 10 and 2 g/l. The results obtained can be summarized as follows: (1) % Cr(VI) extracted increased with an increase of H₂SO₄ acidity, while % Cr(VI) stripped decreased with an increase of H₂SO₄ acidity. (2) In the extraction process total extraction more than 99% and in the stripping process total stripping more than 95% seemed to be obtained by using 8 stage extraction and 7 stage stripping respectively. (3) In the presence of impurities such as Fe, Cu, Ni and Zn in the aqueous phase the extractability of Cr(VI) decreased by the co-extraction of Fe(III) and though Fe(III) was extracted, the extractability of Fe(III) could be kept extremely low by controlling the concentration of Cr(VI) below 20-25 g/l. Cu was not extracted. (4) The extracted species of Cr(VI) with tri-n-butyl phosphate was found to be principally H₂Cr₂O₇⋅TBP in the concentration of Cr(VI) below 10 g/l.

Treatment of Waste Water from Chromium Plating by Solvent Extraction

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