Study on the constant current coulometric titration of potassium dichromate by electro-generated divalent iron and its application to the analysis of total uranium
TANG Lei, LIU Xue-mei, YANG Tian-li, LONG Kai-ming*
Nuclear Physics and Chemistry Institute, Chinese Academy Engineering Physics, Mianyang 621900, China
Abstract：Constant current coulometry is one of the most accurate and precise methods for total uranium measurement. In order to improve the accuracy further and reduce the measurement time, the standard solution of potassium dichromate was titrated by electro-generated divalent iron using the KLT-1 universal coulometer. The effects of constant current coulometric analysis conditions such as the electrolyte composition, the electrolysis current and argon ventilation were investigated experimentally, and two end-point indication methods, namely, the potential drop method and the current rise method were compared. The optimum conditions for coulometric titration were determined as the following: the electrolysis current was 10 mA, argon ventilation was not used, the amount of sulfuric acid was 17 mL, the dosage of 0.5 mol / L Fe2(SO4)3 solution was 7mL and the electrolyte volume was 70 mL. The potential drop method indicated end-point was employed to analyze about 0.7 mg of K2Cr2O7, with the titration efficiency (the percentage between the measured amount and the addition amount of K2Cr2O7) of 99.31% and the relative standard deviation of 0.52 %. The method was used to analyze the self-made uranium standard solution, the relative standard deviation of the analytical results of 50 mg order total uranium was 0.17%.
汤 磊, 刘雪梅, 杨天丽, 龙开明. 电生二价铁滴定重铬酸钾恒电流库仑分析技术的研究及其在铀总量分析中应用[J]. 冶金分析, 2014, 34(2): 6-10.
TANG Lei, LIU Xue-mei, YANG Tian-li, LONG Kai-ming. Study on the constant current coulometric titration of potassium dichromate by electro-generated divalent iron and its application to the analysis of total uranium. , 2014, 34(2): 6-10.
梁述忠, 陈文辉. 恒电流库仑分析法测定硫酸亚铁铵等基准试剂的纯度[J].化学分析计量(Chemical Analysis and Meterage), 2005, 14(5):24-26.
[14]
王征帆. 库仑滴定法定值测定标准物质As2O3[J].科学技术与工程(Science Technology and Engineering), 2009, 9(22):6764-6766.
[15]
Walker C R, Vita O A. The precise determination of uranium in impure uranyl nitrate and uranium oxides[J]. Anal. Chim. Acta, 1970, 49:391-400.
[16]
John S S. A comparison of some analytical techniques for determinating uranium, thorium and potassium in a ranitic rocks[ J]. Research U. S. Geol. Survey, 1997, 5(1):83-91.
[17]
董灵英. 铀的分析化学[M].北京:原子能出版社, 1982.
[18]
李国华, 周永忠. UO2芯块中铀、铀和铀总量的精密测定-恒电流库仑滴定法[J].中国核科技报告(China Nuclear Science and Technology Report), CNIC01344:1-19.
[19]
牟凌, 汪南杰, 叶卫华, 等. 恒电流库仑法测定八氧化三铀中的铀[J].核化学与放射化学(Journal of Nuclear and Radiochemistry), 2006, 28(1):49-64.
