Extraction Kinetics of Fe3+ and In3+ from Sulfuric Acid Medium with D2EHPA

Extraction kinetics of trivalent In3+ and Fe3+ with di(2-ethylhexyl) phosphoric acid(D2EHPA, H2A2) in kerosene from sulfuric acid medium was studied using constant interfacial area method. The effects of temperature, interfacial area, stirring speed, hydrogen ion, D2 EHPA and sulfate concentration on their extraction rate were examined. The results indicated that at 25 ℃ and stirring speed of 70～240 r/min, the apparent activation energy of In3+ extraction was 17.54 k J/mol and the extraction process of In3+ was controlled by diffusion, while the apparent activation energy of Fe3+ extraction was 52.87 k J/mol, Fe3+ was extracted in Fe SO4+, and the extraction process was controlled by chemical reaction at the interface. As D2 EHPA concentration increased, the forward reaction force could be increased to improve the extraction rate. Because the extraction process was the cation exchange, increasing the concentration of hydrogen ion would reduce the extraction rate. Complexation of metal ion with sulfate radical would reduce the extraction rate. Under those conditions, the rate of forward In3+ extraction reaction was expressed as-d CIn3+/dt=10-0.378 [In3+](aq)[H+](aq)-0.376[H2A2](org)0.158, and that of Fe3+ as-d CFe3+/dt=10-2.431 [Fe3+](aq)[H+](aq)-1.526[H2A2](org)0.600.