高锰酸盐氧化-碘量法测定高锰酸盐指数

在高锰酸盐指数的测定方法中，标准碱性法具有较强的抗氯离子干扰能力，但对于高氯离子浓度水样，在酸化后的滴定过程中高锰酸盐可使氯离子氧化导致滴定终点难于辨认。采用高锰酸盐氧化－碘量法（以下简称碘量法）可以较好地解决这一问题。试验得出：碘化钾加入量为４～５ｍＬ（０．５ｍｏｌ／Ｌ），氯离子浓度在１２０００ｍｇ／Ｌ以下对测定结果基本无影响；Ｆｅ３＋对结果有负干扰，当用氟离子掩蔽后，Ｆｅ３＋浓度对测定结果基本上无影响；碘量法的回收率在９６％～１０２％之间。

Determination of Permanganate Value by Permanganate Oxidation-Iondimetry

The standard alkaline method has a better ability to resist chloride ion interference in the determination of Permanganate Value.But when the concentration of chloride ion is high the end point can not be recognized easily because of the oxidation of chloride ion by the permanganate in the titration after acidification.The permanganate oxidation-iondimetry method may be better to solve this problem.The experimental results show that when adding dose of potassium iodide is 4～5 mL(0.5 mol/L) and the concentration of chloride ion is below 12 000 mg/L there is no effect on the determination of Permanganate Value.Iron ion has a negative effect on the determination,but no effect when fluoride ion is use to shield iron ion.The recovery rate of this method is between 96%～102%.