IRON(III) EXTRACTION BY LIX-860 AND ITS INFLUENCE ON COPPER(II) EXTRACTION FROM SULFURIC SOLUTIONS

Solvent extraction of iron(III) by means of the commercial salicylaldo xime LIX 860 and its influence on copper(II) extraction from sulphuric solutions has been studied. Extraction experiments were carried out v arying the equilibration time, temperature, extractant concentration, aqueous pH and the ferric and cupric ions concentrations. Iron(III) ex traction by LIX 860 can be represented by the reaction: Fe-aq(3+) + 3H R(org) reversible arrow FeR(3org) + 3H(aq)(+) in which HR represents t he extractant molecule, Iron(III) extraction can be performed at pH va lues above 1 and the extraction reaction is endothermic, It was determ ined that, for the above reaction, log K-ext(25 degrees C) is - 1.196 and the corresponding values of Delta H degrees, Delta G degrees(25 de grees C) and Delta S degrees(25 degrees C) are 8.6 kJ/mol, 6.8 kJ/mol and 0.006 kJ/mol K, It was also concluded that, under the present expe rimental conditions, copper(II) is extracted preferably to iron(III) a nd the presence of this ion does not appreciably influence the equilib rium constant of the copper extraction reaction by LIX 860.