Supercritical fluid extraction of cobalt with fluorinated and non-fluorinated β-diketones

Supercritical fluid extraction of cobalt ions was evaluated in terms of the ability of the process to extract, solvate, transport and to collect the metal species. The aim of the study was to ensure that a mass balance could be obtained for the metal before and after extraction with supercritical carbon dioxide (CO2). The stability of the ligand and resulting metal complex were assessed as was the synergistic effect of the presence of water in the extraction. Two widely used β-diketones, namely, acetylacetone (AcAc) and hexafluoroacetylacetone (HFAcAc) were chosen to extract spiked cobalt from the surface of stainless steel and >90% of the metal was extracted and collected using the HFAcAc ligand with supercritical CO2.