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基于硫酸-柠檬酸钠介质中,钒(Ⅴ)催化H2O2氧化甲基绿的显色反应,建立了测定痕量钒(Ⅴ)的光度分析新方法。确定了催化褪色反应测定钒(Ⅴ)的动力学条件,催化反应的表观活化能E′a=83.34kJ/mol,反应速率常数K′=2.25×10-4/s。方法线性范围为0.20～80μg/L,检出限为0.88μg/L。方法的表观摩尔吸光系数ε=3.31×105L/(mol·cm)。用于本地钒尾矿中钒含量的测定,相对标准偏差为2.2%～2.9%,标准加入回收率为98.8%～102.9%。
A new spectrophotometric method for the determination of trace vanadium (Ⅴ) was established based on the color reaction of vanadium (Ⅴ) catalyzing the oxidation of methyl green by H2O2 in sulfuric acid - sodium citrate media. The kinetic conditions for the determination of vanadium (Ⅴ) by catalytic fading reaction were determined. The apparent activation energy E’a = 83.34kJ / mol and the reaction rate constant K ’= 2.25 × 10-4 / s. The linear range of the method was 0.20 ~ 80μg / L with the detection limit of 0.88μg / L. The apparent molar absorptivity ε = 3.31 × 105L / (mol · cm). For the determination of vanadium content in the local vanadium tailings, the relative standard deviations were 2.2% -2.9%, and the standard addition recoveries were 98.8% -102.9%.