HDEHP从磷酸介质中萃取U(Ⅵ)的动力学研究

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

摘要: 本文采用恒界面搅拌池法研究了磷酸介质中二-(2-乙基己基)磷酸-环己烷萃取U(Ⅵ)的扩散过程动力学。由测定搅拌速率和温度对萃取速率的影响表明,在较浓的磷酸介质(如4.0mol/lH_3PO_4)中,萃取过程属扩散控制,而在较稀的磷酸介质(如0.5mol/l H_3PO_4)中,萃取过程为化学反应所控制。在扩散控制条件下,通过测定不同萃取条件对萃取速率的影响,可认为在一定磷酸浓度下萃取速率方程为: R_F=K_DUO_2~(2+)(HA)_2_((0))6~(3/2)

Abstract: 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.