Improvement of recovery performance in the solvent extraction of Cu(II) using [bmim][Tf2N] and a β-diketone as extractant and its stripping with supercritical carbon dioxide

Abstract This study deals with the improvement of the recovery performance in the solvent extraction of Cu(II) using the ionic liquid [bmim][Tf 2 N] and the β-diketone 1,1,1-trifluoro-2,4-pentanedione (TFA) as extractant and its stripping with supercritical carbon dioxide. This work describes a modified procedure, which shows better L-L extraction percentages with a decreasing of the concentration of TFA, the contacting time and the volumetric O/A ratio respect to the previously reported tests. Thus, the extraction was implemented with a concentration of TFA in [bmim][Tf 2 N] equal to 60 mol m −3 , a contacting time of 5 min and an O/A ratio equal to 1:7. The stripping of the metal complex from the organic phase was achieved in semi-continuous mode with scCO 2 . This configuration allowed obtaining a stripping percentage higher than the obtained with a previously tested procedure in batch mode with a consumption of CO 2 4.3 times lower than the observed one in previous work.