N,N,N’,N’-四己基丁二酰胺萃取铀、钍及硝酸的机理

Extraction mechanism of U(VI), Th(IV) and nirtic acid with N,N,N’,N’-Tetrahexylsuccinylamide

合成了 N,N,N?N?四己基丁二酰胺(THSA)。以正十二烷为稀释剂研究了THSA萃取硝酸的平衡,认为在低酸度下主要形成THSA·HNO3加合物,在高酸度下主要形成加合物THSA·HNO3和THSA·(HNO3)2;还研究了THSA从硝酸介质中萃取铀、钍的机理,通过考察 HNO3浓度、THSA浓度及温度对铀和钍分配比的影响,得出了萃合物的组成为UO2(NO3)2·THSA和Th(NO3)4·2THSA,并计算出萃取反应的表观平衡常数及热焓。实验结果表明THSA具有较强的对铀、钍萃取能力,并有望实现铀、钍分离。

N,N,N?N?Tetrahexylsuccinylamide(THSA) was synthesized, and used for extraction of HNO3, U(VI) and Th(IV) with THSA in n-dodecane. The HNO3·THSA was suggested as the main adduct in 1.0 mol·L-1 HNO3, and THSA·(HNO3)2 was also present except THSA·HNO3 in 3.7 mol·L-1 HNO3. According to the effects of nitric acid concentration, THSA concentration and temperature on distribution ratios of U(VI) and Th(IV), the compositions of UO2(NO3)2·THSA and Th(NO3)4·2THSA were obtained. The equilibrium constants and thermodynamic functions of extraction reactions have been calculated. The experimental results indicate that THSA can extracted U(VI) and Th(IV) efficiently and a better U-Th separation could be reached in the experimential region.