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本文采用上升液滴法,研究了三辛基氧化膦(TOPO)-环己烷溶液从盐酸体系中萃取U(IV)的动力学.按实验结果在一定的盐酸浓度下,TOPO箤取U(IV)的速率可由下述萃取动力学方程式表示:R=K[U(IV)][TOPO]_(0)在[HCl]=3M和15℃时,计算得萃取速率常数K=3.7x10~(-5).在不同盐酸浓度的溶液中,TOPO萃取U(IV)的速率与盐酸浓度的3/2次方成正比.测定了温度(15～45℃)对萃取速率的影响,求得萃取反应的表观活化能为10.8 kcal/mol. 由实验结果推测,TOPO从盐酸体系中萃取U(IV)的反应可能按下列两步进行:UCl_4+TOPO_(0)=UCl_4·TOPO_(0) (1)UCl_4·TOPO_(0)+TOPO_(0)=UCl_4·2TOPO_(0) (2)而生成界面溶剂配合物的反应(1)是萃取速率的控制步骤.
In this paper, the kinetics of extraction of U (IV) from the system of hydrochloric acid with trioctylphosphine oxide (TOPO) -cyclohexane was studied by the ascending droplet method. According to the experimental results, under the certain concentration of hydrochloric acid, IV) can be expressed by the following extraction kinetic equation: R = K [U (IV)] [TOPO] _ (0) The extraction rate constant K is calculated at [HCl] = 3M and 15 ° C. (-5) .Under the different concentrations of hydrochloric acid, the extraction rate of U (IV) by TOPO is proportional to the third and second power of hydrochloric acid concentration.The influence of temperature (15 ~ 45 ℃) on extraction rate The apparent activation energy of the extraction reaction is 10.8 kcal / mol. It is inferred from the experimental results that the extraction of U (IV) by TOPO from the hydrochloric acid system may take the following two steps: UCl_4 + TOPO_ (0) = UCl_4 · TOPO_ (1) UCl_4 · TOPO_ (0) + TOPO_ (0) = UCl_4 · 2TOPO_ (0) (2) The reaction to generate interfacial solvent complex (1) is the control step of the extraction rate.