Kinetics Measurements in Liquid-Liquid Exchange Applied to Isotopic Separation

摘要

On laboratory scale, a method using calibrated drops, freely falling through a stationary continuous phase, was carried out to study the uranium isotope transfer between free ions dissolved in an aqueous phase and the corresponding complexes of an organic phase. We used an aqueous hydrochloric solution of U exp 4+ at an initial 235 U atom concentration of 0.72% and an organophosphorous extractant containing a U exp 4+ complex at an initial 235 U atom concentration of 0.5%. The isotopic mixing kinetics were measured. The aqueous phase was fed, as calibrated drops, through the stationary organic phase. exp 235 U concentration of the effluent stream was determined as a function of the drop residence time. An isotopic transfer coefficient ksub(A) (cm.s exp -1 ) was calculated. Its variations were investigated as a function of drop size. In the region of small drops the activation energy for ksub(A) was measured. The low value of 6 Kcalorie-mole allows interpretation in terms of diffusional more than chemical transfer resistance. The isotopic exchange has to be analysed by means of mathematic model based on physical characteristics of phases. (Atomindex citation 11:543359)