Solvent extraction of iron(III) by MOC-55 TD: experimental equilibrium study and demonstration of lack of influence on copper(II) extraction from sulphate solutions

Solvent extraction of iron(III) by means of the commercial aldoxime MOC-55 TD and its influence on copper(II) extraction from sulphuric solutions has been studied. Extraction experiments were carried out varying the equilibration time, temperature, extractant concentration, aqueous pH and the ferric and cupric ions concentrations. Iron(III) extraction can be performed at pH values above 1, the extraction being endothermic (Delta H degrees = 52.5 kJ/mol). The extraction of the metal by MOC-55 TD can be represented by the equilibria: [GRAPHICS] where HR represents the extractant molecule. It was also concluded that, under the present experimental conditions, copper(II) is extracted preferably to iron(III) and the presence of this element does not appreciably influence the equilibrium constant of the copper extraction reaction by MOC-55 TD. (C) 1998 Elsevier Science B.V.