Metal extraction from solid matrices using a two-surfactant microemulsion in neat supercritical carbon dioxide

Heavy metal ions including Co(II), Cd(II), Cu(II), Pb(II), Zn(II), Eu(III), La(III), and Sr(II) were extracted from solid matrices by using a water-in-CO2 microemulsion composed of sodium bis-(2-ethylhexyl) sulfosuccinate and a nontoxic perfluoropolyether phosphate in neat supercritical carbon dioxide. The extraction efficiency exceeds 90% according to ICP-AES analysis. The method significantly reduces the amount of liquid waste generated since only a small amount of water and no modifier are needed in contrast to the conventional washing or acid leaching processes.