Selective Foam Fractionation of Chloride Complexes of Zinc(II), Cadmium(II), Mercury(II), and Gold(III)

An experimental investigation is presented of the batch foam fractionation of the chloride complex anions of Zn(II), Cd(II), Hg(II), and Au(III) from 1.0 × 10^-5M (metal concentration) acidic aqueous solutions with the cationic surfactant hexadecyltrimethylammonium chloride. The effect on metal separation is established of the presence of Ci^- over the concentration range 0.01 to 3.0 M, both for solutions containing a single metal and for solutions equimolar in the four metals. At a 0.01 M concentration of chloride, Au(III) can be efficiently foam-fractionated from the other three metals and, at a 0.5 M concentration of chloride, Au(III) and Hg(II) can be efficiently foam-fractionated from Cd(II) and Zn(II).