Galvanic effect of magnetite on electrochemical oxidation of arsenopyrite in acidic culture medium

酸性培养基体系中磁铁矿对砷黄铁矿电化学氧化的原电池效应

The galvanic interaction of arsenopyrite−magnetite in acidic culture medium was investigated by electrochemical measurements,X-ray photoelectron spectroscopy characterization and leaching experiments.The results indicated that the rest potential of magnetite was 321 mV,which was more anodic than 223 mV of arsenopyrite,and the galvanic current was 7.40μA,verifying the existence of the galvanic interaction between arsenopyrite and magnetite.The galvanic potential and polarization curves suggested that the redox behaviors of arsenopyrite dominated the overall galvanic interaction.The galvanic interaction enhanced the electrochemical dissolution of arsenopyrite with the generation of more oxidation products(S^(0),SO_(3)^(2−),SO_(4)^(2−)and AsO_(3)^(3−)) on arsenopyrite and an increase in the chemical reactivity of the surface.Leaching experiments of 6 days showed that the presence of magnetite improved the arsenic release from arsenopyrite by 30 mg/L,and further confirmed the enhanced oxidation of arsenopyrite when coupled with magnetite.

采用电化学测试、XPS和浸出试验,研究酸性培养基体系中砷黄铁矿与磁铁矿之间的原电池效应。结果表明,磁铁矿的静电位为321 mV,高于砷黄铁矿的223 mV,两者之间的原电池电流为7.40μA,证明砷黄铁矿和磁铁矿之间确实存在原电池效应。原电池电位和极化曲线表明,砷黄铁矿的氧化还原行为在整个原电池反应中占主导地位,原电池反应可强化砷黄铁矿的电化学溶解,促进表面氧化产物(S^(0),SO_(3)^(2−),SO_(4)^(2−)和AsO_(3)^(3−))的生成,提高砷黄铁矿表面的化学反应活性。6 d的浸出试验表明,在磁铁矿存在下,砷黄铁矿中砷的溶出浓度提高30 mg/L,进一步证明磁铁矿对砷黄铁矿的氧化具有强化作用。