Determination of trace mercury (Ⅱ) with inhibition of the fading of methylene blue kinetic spectrophotometry
WANG Hong-fu1, SU Zhi-xian*2, ZHANG Su-lan2，LUO Ying2, ZHAO Jing1
1.School of Chemistry and Chemical Engineering, Mianyang Normal Universtity, Mianyang 621000, China; 2.School of Life Science and Technology, Mianyang Normal Universtity, Mianyang 621000, China
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%.
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WANG Hong-fu, SU Zhi-xian, ZHANG Su-lan，LUO Ying, ZHAO Jing. Determination of trace mercury (Ⅱ) with inhibition of the fading of methylene blue kinetic spectrophotometry. , 2011, 31(10): 62-65.
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