硝酸体系中Tc(Ⅶ)与乙异羟肟酸的反应动力学研究  

Reaction Kinetics of Tc(Ⅶ) With Acetohydroxamic Acid in Aqueous HNO_3 Medium

作　　者：晏太红[1] 左臣[1] 郑卫芳[1] 张柏青[1] 张宇[1] 鲜亮[1] 卞晓艳[1] 李传博[1] 

机构地区：[1]中国原子能科学研究院放射化学研究所,北京102413

出　　处：《原子能科学技术》2012年第9期1034-1040,共7页Atomic Energy Science and Technology

摘　　要：采用溶剂萃取法研究了HNO3溶液中乙异羟肟酸(AHA)与Tc(Ⅶ)的相互作用。结果表明,有AHA存在时,Tc在30%TBP/煤油-HNO3体系中的分配比随反应时间下降,在实验条件下反应50h后Tc在两相中的分配基本达到平衡,分配比DTc降至0.03,这表明Tc(Ⅶ)能被AHA还原为亲水性的低价Tc配合物[TcⅡ(NO)(AHA)2H2O]+;溶液吸收光谱显示,反应产物在428nm(ε=2 559L.mol-1.cm-1)和565nm处有吸收峰。通过溶剂萃取法得到Tc(Ⅶ)还原反应的表观反应速率方程式为r=-dc(Tc(Ⅶ))/dt=k′c(Tc(Ⅶ))c1.6(AHA),在18℃下,c(AHA)=1.0mol/L,c(HNO3)=0.50mol/L时半反应时间t1/2=16.5h。进一步研究了溶液中有Pu(Ⅳ)存在时AHA与Tc(Ⅶ)的作用以及Tc分配比的变化。结果表明:Pu(Ⅳ)的存在会加快Tc(Ⅶ)转化为低价态亲水性配合物,而Pu的分配比在过程中基本不变。The kinetics of the reaction of acetohydroxamic acid(AHA) with Tc(Ⅶ) was studied in aqueous HNO3 medium by solvent extraction method.The results show that Tc(Ⅶ) is reduced slowly by AHA to a hydrophilic low-valent species [TcⅡ(NO)(AHA)2H2O]+,which has low distribution ratio(approxamately 0.006) in 30%TBP/kerosene-HNO3 system.The UV-Vis spectrum of the solution after the reaction reveals that the final product has absorption peaks at 428 nm(ε=2 559 L·mol-1·cm-1) and 565 nm.The apparent reaction rate equation in HNO3 medium is r=-dc(Tc(Ⅶ))/dt=k′c(Tc(Ⅶ))c1.6(AHA).t1/2 is determined to be 16.5 h under condition of 18 ℃,c(AHA)=1.0 mol/L and c(HNO3)=0.50 mol/L.The presence of Pu(Ⅳ) in the reaction system will accelerate the reduction of Tc(Ⅶ),while the distribution ratio of Pu keeps constant,which may strongly impact Tc behavior in the spent fuel reprocessing.

关 键 词：Tc(Ⅶ) 乙异羟肟酸 还原 溶剂萃取 

分 类 号：O643.12[理学—物理化学]