Kinetics of the oxidation of Pu(IV) by manganese dioxide
Kinetics of the oxidation of Pu(IV) by manganese dioxide
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二氧化锰氧化 Pu(IV) 的动力学
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
G. Choppin
中科院分区：
文献类型：
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作者：
A. Morgenstern;G. Choppin
在19 ± 2 °C的恒温下，在pH值为2.5至8.2的1.0 M NaCl溶液中，研究了二氧化锰氧化钚（IV）的动力学，二氧化锰浓度为0.01 m2/L至4.97 m2/L。溶液中钚的浓度为6.0（± 1.0）× 10−10 M。钚（IV），（V）和（VI）的分数作为时间的函数，通过从固相中去除钚，然后通过超滤/溶剂萃取程序，使用TTA和HDEHP作为萃取剂测定。以Th（IV）、Np（V）和U（VI）为氧化态模拟物，建立了Pu（IV）、Pu（V）和Pu（VI）的适宜去除条件。在pH2.0 ~ 3.5范围内，二氧化锰对Pu（IV）的氧化反应与二氧化锰浓度呈一级反应，与氢离子浓度呈-0.21级反应。因此，假设Pu（IV）的浓度为一级反应，氧化反应可以用以下速率方程描述：其中k = 3.72（± 0.13）× 10−3（m−2L）（mol− 1 L）−0.21（min）−1。使用本研究中确定的动力学数据，二氧化锰对钚的氧化态分布在各种环境条件下，以及在废液中的影响，可以估计。
Summary The kinetics of the oxidation of plutonium(IV) by manganese dioxide were studied in 1.0 M NaCl over the pH range from 2.5 to 8.2 with variable concentrations of manganese dioxide from 0.01 m2/L to 4.97 m2/L at a constant temperature of 19 ± 2 °C. The concentration of plutonium in solution was 6.0(± 1.0) × 10−10 M. Fractions of Pu(IV), (V) and (VI) as a function of time were determined by removal of plutonium from the solid phase followed by an ultrafiltration/solvent extraction procedure using TTA and HDEHP as extractants. Appropriate removal conditions were established for Pu(IV), Pu(V) and Pu(VI) using Th(IV), Np(V) and U(VI) as oxidation state analogs. In the pH range from 2.0 to 3.5, the oxidation of Pu(IV) by manganese dioxide was first order with respect to the concentration of manganese dioxide and −0.21 with respect to the hydrogen ion concentration. Consequently, assuming a first order dependence with respect to the concentration of Pu(IV), the oxidation reaction can be described by the following rate equation: with k = 3.72(± 0.13) × 10−3 (m−2L)(mol−1L)−0.21(min)−1. Using the kinetic data determined in this study, the influence of manganese dioxide on the oxidation state distribution of plutonium under various environmental conditions as well as in waste solutions can be estimated.