A new strategy for supercritical fluid extraction of copper ions

Complexation combined with supercritical fluid extraction was used to extract Cu2+. The effects of pressure, temperature, and total volume of CO2 on the efficiency of extraction were systematically investigated. The extraction recovery was low (57.32%) only by pure supercritical CO2. Addition of a suitable amount of methanol (v/v=5%) to supercritical CO2 could enhance the extraction of Cu2+ (72.69%, relative standard deviation (R.S.D.)=2.12%, n=3), and the recovery increased largely (90.52%, R.S.D.=2.20%, n=3) in the presence of nonionic surfactant Triton X-100. Reverse micelle formation is presented as a new strategy of improving the extraction of metal ions with supercritical CO2 in this paper.