REDOX BEHAVIOUR OF NEPTUNIUM IN PUREX EXTRACTION PROCESSES

按照顺序，将海王星在纯提取过程中的分布行为，将海王星提取到30%的TBP-十二烷作为硝基酸（3-6 M）和硝基酸（10^<-4>-10^<-2> M）的函数进行了比较。它展示了在硝酸盐和硝酸盐之间的快速equilibrium控制了相对相位的redox潜力，是在转向控制了可提取Np（VI）与不可提取Np（V）的结合比率。Redox潜力可以量化地描述为使用硝酸盐、硝酸盐和硝酸盐解决方案中的活性：E/V = 0.951 + 0.058·log<@D7 {HNO<@D23 @>D2}<@D12 @>D1（/）{HNO<@D22 @>D2}<@D11/2@>D1{H<@D22 @>D2O}<@D11/2@>D1@> D 7还通过对海王星向TOPO-DDecane提取的速率进行调查，确认在相关阶段将进行Np（V）至Np（VI）的氧化。反应的速率是：k/h = 5.44 x {HNO_3}^<1.02>{HNO_2}^<0.56>

In order to clarify the distribution behavior of neptunium in the Purex extraction processes, the equilibrium and rate of the extraction of neptunium into 30% TBP-dodecane were examined as a function of nitrous acid (3-6 M) and nitrous acid (10^<-4>-10^<-2> M) concentrations. It was shown that the rapid equilibrium between nitric and nitrous acids controlls the redox potential of the aqueous phase, which in turn controlls the ratio of the concentrations of extractable Np(VI) to unextractable Np(V). The redox potential can be quantitatively described with using the activities of nitric acid, nitrous acid and water in nitric acid solutions:E/V = 0.951 + 0.058・log<@D7{HNO<@D23@>D2}<@D12@>D1(/){HNO<@D22@>D2}<@D11/2@>D1{H<@D22@>D2O}<@D11/2@>D1@>D7 By examining also the rate of the extraction of neptunium into TOPO-dodecane, the ratedetermining step was confirmed to be the oxidation of Np(V) to Np(VI) in the aqueous phase. The rate of the reaction was obtained to be:k/h = 5.44 x {HNO_3}^<1.02>{HNO_2}^<0.56>