HAsO_2在金电极上的阴极还原行为

采用环盘电极实验和交流阻抗技术等研究了ＨＡｓＱ_２在硫酸钠溶液（ｐＨ＝４．０）中在金电极上的阴极还原行为．结果表明，ＨＡｓＯ_２可以最终还原为 ＡｓＨ_３．整个还原过程可以分为两步：ＨＡｓＱ_２还原为金属Ａｓ和金属Ａｓ进一步还原成ＡｓＨ_３，还原产物ＡｓＨ_３在电极上的吸附较强，溶出性能较差．这两步还原过程在阻抗的复数平面图上呈现二个明显的电容弧，利用 ＥＱＵＩＶＣＲＴ软件对其进行计算机拟合，得到了对应的等效电路以及其中的反应电阻元件的数值．

ELECTROCHEMICAL REDUCTION CHARACTERISTICS OF ARSENOUS ACID AT GOLD ELECTRODE

The cathodic reduction behavior of arsenous acid(HAsO_2) in sodium sulphate solution (pH = 4.0) at a rotating An-disk electrode has been investigated using electrochemical techniques including rotating ring - disk electrode and ac impedance spectroscopy, etc. It is shown that HAsO_2 can eventually be reduced to hydrogen arsenide (AsH_3). The reduction process probably takes place in two stages: HAsO_2 is reduced to metal arsenic and metal arsenic to AsH_3. The adsorption of reduction product, (AsH_3 )_(ad), on An electrode is assumed to be strong and its solubility poor. The electrochemical impedance spectra corresponding to the reduction process from HAsO_2 to AsH_3 show two obvious capacitance raches at high and low frequency regions, respectively, which are simulated using EQUIVCRT software to get equivalent circuits and Values of resistance elements.