Extraction et étude de la structure des complexes du cuivre(II) avec l’acide caprique.

Abstract

This work focuses on the study of the extraction of copper(II) in sulfate media by capric acid (decanoïc acid) at different concentrations from 0.005 to 2M in the chloroform at 25°C. The stoichiometry and structure of complex extracts were determined by the slope method and by UV-Visible spectroscopy. The extracted organometallic complexes into the organic phase are of the type: - CuL2.2HL: of monomeric structure and octahedral geometry. - (CuL2.HL)2: of dimeric structure and octahedral geometry. The extraction equilibria for the two types of complexes are: K12 Cu (CuL2.2HL)org + 2H 2+ + 2 (HL)2,org log Kex(12) = -7.31. K21 2 Cu (CuL2.HL)2,org + 4H 2+ + 3 (HL)2,org log K ex(21) = -14. - At low concentrations of capric acid (0.005-0.08M), the monomeric complex extracted is CuL2.2HL. - When the concentration of capric acid is 0.2M, both monomeric and dimeric forms of complex are in equilibrium in the organic phase according to the following equilibrium: 2 (CuL2.2HL)org (CuL2.HL)2,org + (HL)2,org Kdim - At high concentrations of capric acid (0.4-2M), the dimeric complex extracted is (CuL2.HL)2.