硫酸介质中Pt电极上3-乙氧基-4-羟基苯乙醇酸的电氧化

Electrooxidation of 3-Ethoxy-4-Hydroxy Mandelic Acid in Sulfuric Acid Solution at Platinum Electrode

采用循环伏安曲线法和极化曲线法研究了硫酸介质中的3-乙氧基-4-羟基苯乙醇酸(EHMA)在Pt电极上的电化学氧化过程.循环伏安曲线表明,EHMA的电化学氧化是完全不可逆的,在1.35V(vs.SCE)处出现氧化电流峰;结合线性拟合方法表明,氧化峰电流与EHMA浓度在0.01~0.5mol/L范围内、与硫酸浓度在0~0.25mol/L范围内、与扫描速度平方根在0.05~2V/s范围内呈良好的线性关系;硫酸介质中的EHMA在铂电极上的电氧化过程是由扩散步骤控制的.极化曲线表明,EHMA的电化学氧化反应为表观一级反应;在电极电势为1.2V和1.3V时,表观活化能分别为61.799kJ/mol和52.780kJ/mol;在温度35~50℃范围内,交换电流密度为1.20~2.04×10-6 A/cm2.

The electrooxidation process of 3-ethoxy-4-hydroxy mandelic acid （EHMA） at a Pt electrode is investigated by means of cyclic voltammograms and polarization curves. By determination of the cyclic voltammograms, it is found that the electrooxidation of EHMA is completely irreversible, controlled by the diffusion step, and its oxidation current peak appears at 1.35 V （vs. SCE）. The results of linear fitting show that the plots of oxidation peak currents versus the EHMA concentrations in the range of 0.01-0.5 mol/L, the H2 SO4 concentrations in the range of 0-0.25 mol/L and the square roots of the scanning rates in the potential range of 0.05-2 V/s are almost linear. By determination of the polarization curves, it is indicated that the electrooxidation of 3-ethoxy-4-hydroxy mandelic acid is a first order reaction; the apparent activation energies are 61.799 and 52.780kJ/mol at the potentials of 1.2 V and 1.3 V, and the exchange current density is 1.20-2.04 × 10^-6A/cm2 in the temperature range of 35℃-50℃.