A COMPARATIVE STUDY OF THE TREATMENT OF CHROMIUM ELECTROPLATING WASTEWATER USING TWO EXTRACTANTS, ALAMINE 336 AND ALIQUAT336

摘要

At a molar ratio of extractant to hexavalent chromium, Cr(Ⅵ), of 4 to 1, Aliquat 336 can effectively extract Cr(Ⅵ) with a percentage of extraction greater than 90% over a wide pH range (1.5 to 7). Fairly high concentrations of stripping agents, e.g. 0.5 mol/dm~3 NaOH, are required for effective stripping. At the same molar ratio, Alamine 336 can extract more than 90% of Ct(Ⅵ) over a much narrower pH range (1.5 to 2.5). Cr(Ⅵ) loaded Alamine 336 solutions can be effectively stripped with NaOH at low concentrations, e.g. 0.1 mol/dm~3. The stoichiometries of the Cr(Ⅵ) species in the organic solutions in equilibrium with simulated rinse-waters at different pH values are examined.