A NEW METHOD OF URANIUM PRESEPARATION AND CONCENTRATION FOR NEUTRON-ACTIVATION ANALYSIS

This paper introduces a new type of extractant, sym-dibenzo-16-crown-5 -oxyhydroxamic acid (HL). The extraction of UOBz2+, Na+, K+, Sr2+, Ba2 + and Br- were studied with HL in chloroform. The results obtained sho w that UO22+ can be quantitatively extracted at pH above 5, whereas th e 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 bot h the concentration of the HL and pH are linear, and they have the sam e slope of 2. This suggests that U(VI) appears to form a 1 : 2 complex with ligand. Uranium (VI) can be selectively separated and concentrat ed from interfering elements such Na, K, Sr and Br by solvent extracti on with HL under specific conditions. The recovery of uranium is nearl y 100% and the radionuclear purity of uranium is greater than 99.99%. Therefore, it has greatly improved the sensitivity and accuracy for th e detection of trace uranium from seawater by neutron activation analy sis.