The extraction of Cd(II) from chloride solutions by trilaurylammonium chloride, TLAHCl, dissolved in toluene has been studied by means of metal distribution measurements. The experimental data have been obtained at different chloride concentrations of the aqueous phase (ranging from 1.0 to 3.0 mol dm-3) and applying the constant ionic medium method. The results show an enhancement of the cadmium extraction when the aqueous chloride concentration is increased. The extraction process is explained by assuming that the species CdCl2(TLAHCl)2 and CdCl2(TLAHCI)3 are formed in the organic phase, and the corresponding extraction reactions are: (C d2 + + 2 C l- + 2TLAHCl (org) ⇌ C d C l2 (TLAHCl)2 (org) ; K2; C d2 + + 2 C l- + 3TLAHCl (org) ⇌ C d C l2 (TLAHCl)3 (org) ; K3) This model has been found to be independent of the chloride concentration in the aqueous phase. However, the values of their extraction constants K2 and K3 are different for the various chloride concentrations used. The values of K2 and K3 at a different chloride concentration, I, have been correlated by using the specific-interaction theory (S.I.T.), and the interaction coefficient for the Cd2+, Cl- ions, as well as, the thermodynamic constants, Kno, have been determined. © 1988 Pergamon Press plc.
|Publication status||Published - 1 Jan 1988|