基于稀HCl介质中，在加热60 ℃条件下，Hg(Ⅱ)对溴酸钾氧化甲基蓝褪色反应具有显著阻抑作用，据此建立了阻抑褪色动力学光度法测定痕量Hg(Ⅱ)的光度分析方法。在选定实验条件下，非阻抑反应体系（吸光度为A0）与阻抑反应体系(吸光度为A)在602 nm处的吸光度差值ΔA与Hg(Ⅱ)的质量浓度(ρ)在0.007 7～1.50 μg/25 mL范围内呈良好的线性关系，检出限为2.21×10-10 g/mL。测定了动力学参数，该阻抑反应为准一级反应，表观速率常数K′=2.73×10－4/s，表观活化能为41.32 kJ/mol。方法用于废水样品中痕量汞(Ⅱ)的测定，RSD为2.0%。
Abstract
In this paper, we adopt the inhibition kinetic spectrophotometric method to measure the trace amount of mercury(Ⅱ). In the diluted hydrochloric acid medium by heating at 60 ℃, mercury(Ⅱ) has a significant inhibitory effect on the oxidation of methylene blue by potassium brominate, thus we established the theory of inhibitory kinetic spectrophotometry determination of mercury(Ⅱ). Under the selected experimental conditions, the difference between the absorbance of the non-inhibitory reaction (absorbance A0) and the inhibitory reaction (absorbance A) at the wavelength of 602 nm has a good linear relationship with the concentration of mercury(Ⅱ) in the range of 0.007 7-1.50 μg/25 mL, which also has a detection limit of 2.21×10-10 g/mL. Kinetic parameters were determined, which subject to a pseudo first-class catalytic reaction, and the apparent rate is a constant of K′=2.73×10-4 /s, while the apparent activation energy is 41.32 kJ/mol. This method has a good selectivity for measuring the trace amount of mercury(Ⅱ) in waste water samples, and the RSD of the determination was 2.0%.
关键词
阻抑动力学光度法 /
溴酸钾 /
甲基蓝 /
汞(Ⅱ)
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Key words
inhibitory kinetic spectrophotometric /
potassium brominate /
methyl blue /
mercury(Ⅱ)
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中图分类号：
O657.32
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参考文献
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