KINETIC STUDIES ON THE EXTRACTION OF U(Ⅵ) FROM PHOSPHORIC ACID MEDIUM WITH HDEHP

The kinetics of the extraction of U(Ⅵ) from phosphoric acid solution with di-(2-ethyl) phosphate (HDEHP) in cyclohexane is investigated using Lewis cell technique. The extraction rate is determined as a function of the stirring speed and temperature. It is shown that the extraction rate of U(Ⅵ) might be diffusion controlled at the concentration of 4-6 mol/1 H3PO4 aqueous solution, and it might be interfacial chemical reaction controlled at the concentration of 0.5mol/1 H3PO4 aqueous solution. For the diffusion controlled system, the extraction rate expression is found to be pseudo-first order in the concentration of U(Ⅵ) and 3/2 order in the concentration of HDEHP respectively, and the rate of extraction is nearly independent on temperature.