天青Ⅰ-高碘酸钾-Triton X-100体系催化动力学光度法测定痕量铈

Catalytic kinetic spectrophotometric determination of trace cerium Ⅳ with azure Ⅰ-potassium periodate-Triton X-100 system

在H3PO4介质中,增敏剂非离子表面活性剂Triton X-100存在下,痕量铈(对高碘酸钾氧化天青Ⅰ的反应具有催化作用,据此建立一种测定痕量铈(的新方法。研究了吸收光谱、试剂用量、干扰离子等因素的影响,测定了动力学参数。在最佳实验条件下,方法线性范围为0～80μg/L,检出限为4.58×10-7g/L;催化反应为动力学零级反应,表观活化能为96.04kJ/mol,反应速率常数为3.61×10-3/s;反应在表面活性剂存在下,灵敏度提高3倍。此法用于稀土氧化物中铈的测定,相对标准偏差小于2.5%,加标回收率为100%～103%。

A new catalytic discoloring kinetic spectrophotometric method for the determination of the trace Ce（Ⅳ） was studied. The method was based on the catalytic effect of cerium（Ⅳ） on the oxidation of azure I by KIO4 in the presence of non-ionic surface of Triton X-100 as sensitizer and in H3PO, medium. The effects of absorption spectra, acidity, concentrations of reagent, and the influence of coexistence ions on the reaction were discussed, and the kinetic conditions were studied. Under the optimum conditions, the linear range of the method was 0--80μg/L. The detection limit was 4.58× 10^-7 g/L. The catalytic reaction was the zeroth order one. The apparent activation energy and the reaction rate constant was found to be 96.04 kJ/mol and 3.61 × 10^-3/s, respectively. The sensitivity was increased by 3 times in the presence of surfactant. The method was used in the determination of cerium in rare earth oxides,with the relative standard deviation below 2.5% and the average recovery of 100%- 103%.