STOICHIOMETRIC RELATION FOR THE EXTRACTION OF THE GOLD-THIOUREA COMPLEX WITH D2EHPA

The stoichiometric relation for the solvent extraction of gold from acidic thiourea solutions was studied with di(2-ethylhexyl) phosphoric acid (D2EHPA). The results showed that the gold-thiourea complex was solvated with five molecules of the D2EHPA monomer and that the extracted species were not associated with each other. The extraction reaction would be as follows: [Au(CS(NH2)(2))(2)(+)](aq) + 3[R(2)H(2)](org) = [Au(CS(NH2)(2))(2)R . 5RH](org) + [H+](aq) The equilibrium constant for the reaction was found to be 0.398.