紫外脉冲荧光法测定微量铀的研究

Abstract: 

紫外脉冲荧光法是一种通过液体激光来直接测定微量铀的方法。在采用紫外脉冲荧光法分析面包酵母吸附放射性核素铀后溶液剩余铀浓度之前，研究了荧光增强剂、pH 值、以及温度对微量铀浓度工作曲线的影响。结果表明：当pH > 3时，400 μL 荧光增强剂可以充分缓冲溶液，不同pH 值下测得的荧光计数基本保持恒定，即待测溶液pH值不会影响铀浓度的测量；随着温度的升高，荧光计数近似线性下降，并在室温23.6℃时得到了铀质量浓度范围为0:120 μg/L 的工作曲线。在此基础上研究了酵母菌对放射性核素铀的吸附作用，为使吸附剂达到最高效利用，对溶液pH 值、吸附速率进行了批次实验，并通过紫外脉冲荧光分析法进行测量, 发现达到吸附平衡所需的最短时间为180 min，吸附的最佳溶液pH 值为5.8 左右。

The method of pulse ultraviolet fluorescence was employed to analyze the concentration of radioactive nuclide uranium after adsorbed by baker’s yeast. Influences of fluorescent enhance reagent, pH value, and temperature on measurement of the concentration of trace uranium were investigated. The results showed that 400 μL fluorescent enhance reagent was greatly enough to buffer the solution when pH > 3 and the counts of fluorescence kept constant with the variation of pH, which indicates that the pH of solutions doesn’t affect the determination of uranium concentration, moreover, the counts of fluorescence declined linearly as the increase of the temperature. In addition, the working curve of the determination of uranium concentration within 0.1 20 μg/L was obtained when the temperature was 23.6 ℃. On this basis, the adsorption of uranium by baker’s yeast was studied. For the adsorption of radioactive nuclides of uranium by baker’s yeast to achieve the best use, the batch experiments were carried out on the rate of adsorption and pH of solutions. The method of pulse ultraviolet fluorescence was used to measure and found that the minimum time required to reach adsorption equilibrium was 180 min and the optimum pH value of solutions was about 5.8.