铁-高碘酸钾-甲基绿体系阻抑动力学光度法测定铁尾矿中铁

在盐酸-邻苯二甲酸氢钾介质中, 铁(Ⅲ)对高碘酸钾氧化甲基绿的褪色反应有阻抑作用, 且阻抑反应与非阻抑反应在458nm波长处的吸光度差值与铁的质量浓度在一定的范围内呈良好的线性关系, 据此建立了阻抑动力学光度法测定痕量铁的新方法。测定了阻抑褪色反应的动力学参数, 得到阻抑反应的表观活化能E_a=0.85kJ/mol, 反应速率常数K=6.0×10^-4/s。方法的线性范围在20～120μg/L之间, 检出限为8.39μg/L。方法用于本地铁尾矿中铁含量的测定, 测定结果的相对标准偏差为2.4%~3.3%, 标准加入回收率在97%~105%范围。

Inhibitory kinetic spectrophotometric determination of iron in iron tailings with iron-potassium periodate-methyl green system

In hydrochloric acid - potassium acid phthalate medium, iron had inhibitory effect on the fading reaction of methyl green oxidized by potassium periodate. Moreover, the absorbance difference between inhibitory reaction and non-inhibitory reaction at 458 nm showed good linearity to the mass concentration of iron in certain range. On the basis of this fact, a new determination method of trace iron by inhibitory kinetic spectrophotometry was established. The kinetic parameters of inhibitory fading reaction were measured. The apparent activation energy of inhibitory reaction was Ea = 0.85 kJ/mol, and the reaction rate constant was K = 6.0×10^-4/s. The linear range of method was in range of 20-120 μg/L, and the detection limit was 8.39 μg/L. The proposed method was applicable for the determination of iron content in local iron tailings, with relative standard deviation (RSD) of determination results in the range 2.4 %-3.3 % and the recoveries of standard addition between 97 %-105 %.