用预浓集分离中子活化分析法测定海水中微量铀

以二苯基-16冠-5-氧代氧肟酸(HL)作为一种新型萃取剂,研究了对U(VI),Na~+,K~+,Sr~(2+),Ba~(2+)和Br~- 等离子的萃取.结果表明,在一定条件下,U(VI)可以定量地被萃取,而Na~+,K~+,Sr~(2+),Ba~(2+)与Br~-等其它离子则几乎全部留在水相.在萃取过程中,HL与U(VI)形成了组成为2:1的萃合物.并建立了自海水中浓集和分离铀的方法,将它与中子活化分析技术相结合,满意地实现了海水中微量铀的测定.     

Progress in neutron activation analysis for uranium

A new type of extractant, sym-dibenzo-16-crown-5-oxyhydroxamic acid (HL) is introduced. The extractions of UO22+, Na+, K+, Sr2+, Ba2+ and Br- were studied with HL in chloroform. The results obtained show that UO22+ can be quantitatively extracted at pH values above 5, whereas the extractions of K+, Na+, Sr2+, Ba2+ and Br- are negligible in the pH range of 2 - 7. The dependence of the distribution ratio of U(VI) on both the concentration of the HL and pH are linear, and they have the same slope of 2. This suggests that U(VI) appears to form a 1:2 complex with ligand. Uranium(VI) can be selectively separated and concentrated from interfering elements such as Na, K, Sr and Br by solvent extraction with HL under specific conditions. The recovery of uranium is nearly 100% and the radionudear purity of uranium is greater than 99.99%. Therefore, neutron activation analysis has greatly improved the sensitivity and accuracy for the detection of trace uranium from seawater.