Extraction and stripping of Cr(VI) from aqueous solution by solvent extraction

The solvent extraction of Cr(VI) from an aqueous solution by hexadecyl trimethyl ammonium bromide (HTAB) in amyl alcohol was investigated at 27°C. The maximum extraction efficiency was obtained at pH 1.0 ± 0.1. Chromate is an anionic form; therefore, it requires a cationic carrier for the extraction purpose and HTAB acts as cationic carrier in this study. The efficiency of extraction decreased with increasing the chromium concentration. The extracted Cr(VI) in the organic phase can be back extracted into 0.2 mol/L sodium nitrate. The important experimental parameters examined were: the effect of HTAB concentration, the effect of pH, the effect of Cr(VI) concentration, the effect of equilibrium time, and the effect of temperature, aqueous to organic phase ratio, and various stripping agents. Real effluent was also studied under optimized condition [Cr(VI) concentration 10 mg/L at pH 1.0 ± 0.1, carrier concentration = 0.06 mol/L, stripping concentration = 0.2 mol/L, and equilibrium time = 5 min at 27°C] and satisfactory result has been found.