高碘酸钾-二甲苯蓝FF体系催化动力学光度法测定痕量铱Ⅳ

Catalytic kinetic spectrophotometric determination of trace iridiumⅣ in potassium periodate-xylenecyanol FF system

在0.02 mol/L硫酸介质中及95℃的加热条件下,铱（Ⅳ）高碘酸钾氧化二甲苯蓝FF的褪色反应具有显著催化作用,据此建立了催化动力学光度法测定痕量铱（Ⅳ）的新方法。试验结果表明,该催化反应为准一级反应,在选定的实验条件下,非催化反应体系与催化反应体系在615 nm处的吸光度差值△A与铱（Ⅳ）的质量浓度在0.287~4.00μg/L范围内呈良好的线性关系,方法检出限为1.828×10-11g/mL,反应的表观速率常数为1.715×10-3/s,表观活化能为71.00 kJ/mol。该方法用于分子筛催化剂和活性碳中痕量铱（Ⅳ）的测定,其回收率在96.0%~107.4%之间,与AAS法比较,结果相吻合。

On the basis of catalytic action of iridium（Ⅳ） on the oxidation reaction of xylene cyanol FF by the potassium periodate in the medium of 0.02 mol/L H2SO4 and heating at 95 ℃, a new catalytic ki- netic spectrophotometry for the determination of iridium（IV） is established. The experiment results show that this reaction is first-order kinetic one. Under the optimal conditions, the linear scope is 0. 287-4.00 μg/L for iridium and detection limit is 1. 828 × 10^-11 g/L iridium at the wavelength of 615 nm. The rate constant of this reaction is 1. 715 N 10 3/s, and the activated energy of the reaction is 71.00 kJ/mol. The method has been used to the determination of trace amounts of iridium（IV）in the molecular sieve catalyst and activated carbon with the recovery of 96.0 %-107.4 % and the results are consistent with those obtained by atomic absorption spectrometry.