The role of some compounds on extraction of chromium(VI) by amine extractants

The extraction of hexavalent chromium, Cr(VI), from hydrochloric acid aqueous solution using Aliquat 336 and Alamine 336 extractants was performed under different experimental conditions. The data clarify that one molecule of amine extractants shares with approximately one molecule of HCl to extract two molecules of Cr(VI) from 1M HCl aqueous solutions. The extraction is an exothermic process and possesses enthalpy change values of -41.02 and -28.08 kJ mol(-1) for the extraction by Aliquat 336 and Alamine 336, respectively. The presence of potassium chloride greatly increases the extraction of Cr(VI) by amine extractants while the addition of some phenolic compounds such as phenol, dichlorophenol, o-nitrophenol and beta-naphthol decreases this extraction under the same experimental conditions.