用速差动力学光度法同时测定工业废水中的Cr(Ⅵ)和Mn(Ⅶ)

Simultaneous Determination of Chromium (Ⅴ) and Manganese (Ⅶ) in Industrial Wastewater by Differential Reaction Rate Kinetic Spectropbotometry

在酸性介质中，铬（Ⅵ）和锰（Ⅶ）都能氧化玫瑰桃红R褪色，且氧化速率不同。为此，利用比例方程法，建立了速差褪色动力学光度法同时测定铬（Ⅵ）和锰（Ⅶ）的新方法。铬（Ⅵ）和锰（Ⅶ）的测定范围分别为0～10．0μg／mL和0～8．0μg／mL。应用于工业废水中铬（Ⅵ）和锰（Ⅶ）的同时测定，铬（Ⅵ）和锰（Ⅶ）的相对标准偏差分别为1．08％～2．13％和0．78％～1．27％；加标回收率分别为97．2％～99．4％和95．3％～96．9％，结果令人满意。

A novel differential reaction rate kinetic spectrophotometric procedure was established for the simultaneous determination of Cr(Ⅵ) and Mn( Ⅶ) in industrial wastewater, by taking into account the reaction of oxidizing and fading of Bordeaux - red in the presence of Cr(Ⅵ) and Mn(Ⅶ) in aqueous H2SO4 medium and the different oxidizing rates of the Bordeaux - red in the two cases. The method was used to simultaneously determine the Cr(Ⅵ) and Mn(Ⅶ) in an industrial wastewaler. It was found that the linear ranges for the determination of the Cr (Ⅵ) and Mn (Ⅶ) in the wastewater using the established method were 0 - 10. 0 g/mL and 0 -8. 0 g/mL, respectively. The corresponding relative standard deviations for the measurement of Cr (Ⅵ) and Mn (Ⅶ) were 1.08% -2. 13% and 0.78% -1.27, respectively; while the recovery rates for Cr(Ⅵ) and Mn(Ⅶ) were 97. 2% -99.4% and 95.3% -96.9%, respectively. Thus it was supposed that the titled method could be well applied to the simultaneous determination of the Cr(Ⅵ) and Mn(Ⅶ) in industrial wastewater.