Extraction of magnesium and copper using a surfactant and water in supercritical carbon dioxide

Magnesium and copper were extracted in supercritical carbon dioxide with the addition of a surfactant, ammonium carboxylate perfluoropolyether, and water. For Mg2+ the percent extracted reached a maximum of 65% at a temperature of 393 K, a pressure of 220 bar and a mole ratio of water to surfactant, w 0 of 185. For Cu2+ the maximum percent extracted was 73% at a temperature of 333 K, a pressure of 250 bar and a w 0 of 333. The influence of parameters including molar ratio of surfactant to metal and molar ratio of water to surfactant was examined for Mg2+ extraction at a temperature of 333 K and pressure of 150 bar. The percent Mg2+ extracted increased from approximately 19–31% as the mole ratio of surfactant to Mg2+ increased from 0.4 to 4. The percent extracted does not change appreciably with further increases in surfactant/metal ratio. The percent Mg2+ extracted increased from 5% up to 31% as the molar ratio of water to surfactant increased from 0 to 5.6. Further increases of molar ratio of water to surfactant showed no significant increase in metal extracted. The system was operated as a closed-system until equilibrium was achieved.