Thermodynamics of Solvent Extraction of Rare and Scattered Metal-Indium with Diethylhexylmonothiophosphoric Acid

Abstract

The thermodynamics of extracting In(III) with diethylhexylmonothiophosphoric acid as an extractant in a H2SO4 system is reported. The equilibrium molalities of In3+ ions were measured at a high acidity and ionic strengths varying from 0.1 to 2.0 mol/kg in an aqueous phase containing Na2SO4 as the supporting electrolyte. The values of the standard extraction constant K0 at various temperatures were obtained by the methods of extrapolation and polynomial approximation. The equation lgK0 = −31.93 −5.93 ×103/T +6.15×10−2T was also obtained and the thermodynamic quantities for the extraction process were calculated.