Extraction equilibrium of copper by versatic acid.

Abstract

The distribution equilibrium in the solvent extraction of copper (II) by w-hexane solution of Versatic 10, a commercial carboxylic acid produced by Shell Chemical Co. Ltd., from nitrate medium was measured at 30°C. The stoichiometric relation in this copper extraction reaction was found to be expressed as follows. 2Cu2+aq. +3 H2R2org. ?? (CuR2•HR)2org.+4H+aq. Kewhere the equilibrium constant was determined as Ke=1.10 × 10-13. Also, the aqueous solubility of Versatic 10, which is an indispensable datum for the economic evaluation of the commercial-scale extraction, was measured and was interpreted quantitatively in terms of the following two equilibria. H2R2org. ?? 2 HRaq. K1 HRaq. ?? H+aq.+R-aq. K2where the equilibrium constants, K1 and K2 were found to be 9.6 ± 10-7 mol/l and 1.1 × 10-6 mol/l, respectively.