Synergistic effects of organophosphorus compounds on the extraction of copper from aqueous nitrate medium with N-(thioacetyl)benzamide into toluene

The extraction behaviour of Cu(II) from an aqueous nitrate medium employing (N-thioacetyl)benzamide (HL) in toluene has been investigated in presence of several organophosphorus donors like, tri-octyl phosphine oxide (TOPO), tri-butyl phosphine oxide (TBPO) and tri-phenyl phosphine oxide (TPPO) at pH 5.0. The synergism was found in presence of neutral donors due to the formation of the adduct [Cu(L)(2)center dot(S)] in toluene (S denotes neutral donor). The overall equilibrium constant for each of the three ternary complexes and also for binary system were calculated from extraction data. It is found that the extent of extraction of Cu(II) in organic phase both as the binary complex as well as ternary complex increase with increase in temperature. The temperature dependence of the equilibrium constants were investigated in order to evaluate the thermodynamic parameters like enthalpy (Delta H(0)), entropy (Delta S(0)) and free energy (Delta G(0)). Extraction mechanism was supported by IR spectra of ternary adduct.