Solvent Extraction of Mercury(II), Zinc(II) and Cadmium(II) from Hydrochloric Acid Solutions by Dihexyl Sulfoxide

Abstract

Solvent extraction of mercury(II), zinc(II) and cadmium(II) from hydrochloric acid solutions by dihexyl sulfoxide(DHSO, R₂SO) in benzene has been investigated under different conditions. The organic extracts were examined by infrared, Raman and NMR spectroscopies. As the results, the following equilibrium equations are proposed for the extraction of mercury(II), zinc(II) and cadmium(II) from hydrochloric acid solutions by DHSO: MCl₂(a)+2R₂SO(o)⇄MCl₂·2R₂SO(o), MCl^-₃(a)+H⁺(a)+3R₂SO(o)⇄HMCl₃·3R₂SO(o), MCl^2-₄(a)+2H⁺(a)+2R₂SO(o)⇄H₂MCl₄·2R₂SO(o), where M=Hg, Zn or Cd, in which (a) and (o) represent the aqueous and organic phases, respectively. In addition, when mercury loading increases, it is seen that the equilibrium consists of HgCl₂(a)+R₂SO(o)⇄HgCl₂·R₂SO(o).