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The extraction of Au(III) from an aqueous acidic medium with N-(thioacetyl)benzamide in chloroform was studied in the presence of organophosphorus donors (tributylphosphine oxide, triphenylphosphine oxide, tributyl phosphate) at pH 3.0 using radiotracer technique. The influence of various parameters on the extraction equilibrium was examined. The extent of extraction of Au(III) in the form of the binary complex increases with temperature, but the reverse trend is observed with the ternary complex. The overall equilibrium constants for each of the three ternary extraction systems were estimated, and the role of different thermodynamic functions is discussed. The extraction mechanism is supported by the IR spectra of the ternary adduct.

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The extraction behavior of Cu(II) from an aqueous nitrate medium employing b-hydroxynaphthaldoxime in carbon tetrachloride has been investigated in the presence of several organophosphorus donors like tri-octyl phosphine oxide, tri-butyl phosphine oxide, and tri-butyl phosphate at pH 1.5. The concentration of the metal was measured by atomic absorption spectrophotometry. Synergism was observed when neutral donor was added because of the formation of the adduct [Cu(L) 2 .(S)] in CCl 4 (S denotes neutral donor). The equilibrium constants of the binary system using b-hydroxy-naphthaldoxime and the ternary system involving another addition of an organophosphorus compound were calculated from the extraction date obtained. Furthermore, the temperature dependence of the equilibrium constants was also investigated to evaluate standard enthalpy (DH°), entropy (DS°), and free energy (DG°) of the reactions proposed.

The extraction behaviour of Ag(I) from an aqueous nitrate medium employing (N-thio acetyl) benzamide(HA) in n-butanol has been investigated in presence of several organophosphorus donors like, tri-butyl phosphine oxide, tri-phenyl phosphine oxide and tributyl phosphate at pH 4.0 adopting radio tracer technique. The synergism was found in presence of neutral donors due to the formation of the adduct [Ag (A) (H 2 O) (B)] in n-butanol (B 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 was found that the extent of extraction of Ag (I) in organic phase both as the binary complex as well as ternary complex increased with increase in temperature. The temperature dependence of the equilibrium constants were investigated in order to evaluate the thermodynamic parameters like enthalpy (∆H°), entropy (∆S°) and free energy (∆G°). Extraction mechanism was finally supported by I.R spectra of ternary adduct.