EXTRACTION EQUILIBRIA OF GALLIUM(III) AND THALLIUM(III) WITH DIHEXYL SULFIDE FROM HYDROCHLORIC ACID

Abstract

The extraction equilibria of gallium(III) and thallium(III) from hydrochloric acid with dihexyl sulfide (DHS=S) in 1, 2-dichloroethane were measured at 303 K to examine the effects of the concentrations of hydrochloric acid and dihexyl sulfide. The stoichiometric relation of the extraction reaction of gallium(III) was found to be:
GaCl₃+S^→_←;GaCl₃S;K_{e, Ga}
where the equilibrium constant was evaluated as K_{e, Ga}=1.9×10²dm³/mol.
Extraction of thallium(III) was found to be expressible by the following two stoichiometric relations for low and high concentration regions of hydrochloric acid, respectively.
TlCl₃+H⁺+Cl^-- + 2S^→_←HTlCl₄; K_{e, T1}
TlCl₃+2H⁺+2Cl^-+S^→_←H₂TlCl₅S; K_{e, T1}
where the equilibrium constants were evaluated as K_{e, T1} = 4.0×10⁶ (dm³/mol)⁴ and K_{e, T1}=1.6×10⁵ (dm³/mol)⁵.