论文部分内容阅读
硝酸介质中对U(Ⅵ)的光化学还原,选用肼为光还原剂兼有使还原生成的U(Ⅳ)稳定的特点。本报告以氩离子激光器4880激光照射UO_2(NO_3)_2—N_2H_5·NO_3—HNO_3溶液体系,研究了U(Ⅵ)—U(Ⅳ)的光化还原作用。实验测出光还原产生U(Ⅳ)和消耗肼的克分子比例关系R,当[HNO_3]≤2M 时,R～2。讨论了体系温度、肼浓度、铀酰离子浓度及硝酸浓度对光化还原U(Ⅵ)—U(Ⅳ)量子产额φ的影响。结果指出,随体系温度上升,φ和U(Ⅳ)生成速率 v 均逐渐提高。当[N_2H_5·NO_3]<0.5M 时,随[N_2H_5·NO_3]上升,φ提高很快,此时 lg v～1g[N_2H_5·NO_3]的关系曲线呈斜率为0.5的直线。与乙醇体系的结果不同的是,[N_2H_5·NO_3]达到4M
The photochemical reduction of U (Ⅵ) in nitric acid medium is characterized by the use of hydrazine as a photo-reductant and the stabilization of U (Ⅳ) generated by reduction. In this report, the photolysis of U (Ⅵ) -U (Ⅳ) was studied by irradiating UO_2 (NO_3) _2-N_2H_5 · NO_3-HNO_3 solution with 4880 Argon laser. The relationship between the molecular weight R (U (IV)) and the hydrazine - consuming R (photoreduction) was measured experimentally. When [HNO3] ≤2M, R ~ 2. The effects of system temperature, hydrazine concentration, uranyl ion concentration and nitric acid concentration on the quantum yield φ of photochemical reduction U (Ⅵ) -U (Ⅳ) were discussed. The results show that with the increase of temperature, the formation rates of φ and U (Ⅳ) gradually increase. When [N_2H_5 · NO_3] <0.5M, φ increases rapidly with the rise of [N_2H_5 · NO_3]. At this time, the curve of lg v ~ 1g [N_2H_5 · NO_3] shows a straight line with a slope of 0.5. Different from the result of ethanol system, [N_2H_5 · NO_3] reaches 4M