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本文研究了铀萃取工艺过程有机相中微量铀的测定方法。在pH值为7.5—9.0条件下,用二甲基甲酰胺作“互溶剂”,乙醇作稀释剂,在均相有机溶液中,直接用2—(5—溴—2吡啶偶氮)—5—二乙氨基苯酚(简称5—Br—PADAP)作铀的显色剂以分光光度法测定有机相中微量铀。在二甲基甲酰胺和乙醇体系中,5—Br—PADAP与铀形成的络合物在波长578毫微米处有最大吸收,且灵敏度较高,克分子吸光系数ε=7.0×10~4,当使用1.2—环己烷二氨基四醋酸(CyDTA)、磺基水杨酸和氟化钠组成的混合掩蔽剂时,许多元素不干扰测定,只有钒(Ⅴ)铬(Ⅲ)有干扰;但与铀量相当时不干扰,应用5—Br—PADAP光度法直接测定有机相中微量铀,获得较好的结果。
This paper studies the determination of trace uranium in the organic phase of uranium extraction process. Dimethylformamide was used as a “mutual solvent” at pH 7.5-9.0, and ethanol was used as a diluent in a homogeneous organic solution directly treated with 2- (5-bromo-2-pyridylazo) -5 - Diethylaminophenol (referred to as 5-Br-PADAP) as uranium chromogenic reagent spectrophotometric determination of trace amounts of uranium in organic phase. In dimethylformamide and ethanol system, the complex formed by 5-Br-PADAP and uranium has the maximum absorption at the wavelength of 578 nm and the high sensitivity. The molar absorptivity ε = 7.0 × 10 -4, When mixed masking agents consisting of 1.2-cyclohexanediaminotetraacetic acid (CyDTA), sulfosalicylic acid and sodium fluoride were used, many of the elements did not interfere with the assay but only vanadium (V) chromium (III) interfered, but When the amount of uranium is equivalent, the uranium content in the organic phase is directly measured by 5-Br-PADAP spectrophotometry, and good results are obtained.