3,3′,5,5′-四甲基联苯胺分光光度法测定水和废水中总铬

Spectrophotometric Determination of Total Amount of Chromium in Water with 3,3′,5,5′ Tetramethylbenzidine

提出了３，３′，５，５′－四甲基联苯胺（ＴＭＢ）测定水和废水中总铬的分光光度法。在Ｈ２ＳＯ４介质中，用ＫＭｎＯ４将水中所有铬氧化成六价铬，而铬（Ⅵ）能定量氧化ＴＭＢ生成黄色化合物。该化合物的最大吸收波长位于４５０ｎｍ，表观摩尔吸光系数为１．０４×１０５Ｌ·ｍｏｌ－１·ｃｍ－１，铬量在０～０．５０ｍｇ／Ｌ范围内服从比尔定律，用本文提出的方法测定了河水和电镀废水中的总铬，结果满意。

A sensitive spectrophotometric method for the determination of total amount of Chromium with 3,3′,5,5′ tetramethylbenzidine(TMB) has been developed.After Chromium in water was oxidized to Chromium (Ⅵ) by KMnO 4,a yellow compound was produced from the oxidation of TMB by Chromium(Ⅵ).The compound gives a high absorption at 450nm .The apparent molar absorptivity is 1.04×10 5L·mol -1 ·cm -1 .The system obeys Beer's law in the range of 0～0 50mg/L.The method has been applied to water samples with satisfactory results.