Abstract: The effect of initial concentration and pH value of the uranyl nitrate solution on the uranyl ion (UO2+2) hydrolysis reaction was studied by spectrophotometry. The maximum absorption wavelength of the obtained complexes in the reaction of UO2+2 ions with arsenazo (Ⅲ) at different pH values was also investigated. The results show that the absorption wavelength is 652 nm in the range of pH 3.0~7.0. It is easier for the uranyl nitrate solution to hydrolysis at higher pH value than the lower in the range of pH 4.0~6.0 at the same UO2+2 concentration. The uranyl solution at high concentration is prior to occurring hydrolysis reaction in the same pH value. Lowest pH values of various uranyl solutions were obtained for hydrolysis reaction. The results indicate that the concentration of uranyl solution should not exceed 1.000×10-3 mol/L at pH 5.0.

Key words: Uranyl ion, Hydrolysis, Spectrophotometry, Initial concentration, pH

摘要： 利用分光光度法研究了硝酸铀酰水溶液的初始浓度和p H 值这两个因素对铀酰离子( UO2+ 2 ) 水解反应的影响, 同时考察了不同p H值条件下, UO2+ 2 与偶氮胂( Ⅲ) 显色后的最大吸收波长。实验结果表明, 当p H 值为3. 0~7. 0时, 偶氮胂( Ⅲ) 显色后的最大吸收波长均为6 5 2n m; 当硝酸铀酰溶液浓度相同、 p H值在4. 0~6. 0时, 高p H值环境中 UO2+ 2 更易发生水解反应, p H值相同时, UO2+ 2 浓度越大越容易发生水解反应, 得到了不同 UO2+ 2 浓度溶液p H 。 p H 5. 0 , UO 1. 0 0 0×1 0 m o l / L。

关键词: 铀酰离子, 水解, 分光光度法, 初始浓度, p H