亚硫酸钠在碱性硫脲溶金体系中的电化学行为

Electrochemical Behavior of Sodium Sulfite in Alkaline Thiourea System for Gold Dissolution

用电化学工作站测试金电极和铂电极的极化曲线和交流阻抗,研究亚硫酸钠对碱性硫脲溶解金的影响。结果表明,亚硫酸钠对金的腐蚀电位(Ecorr)为-0.776 V,远低于硫脲,腐蚀速率为0.014mm/a,是有效的溶金试剂;在铂电极上测试,硫脲在碱性条件下会发生不可逆氧化分解,但亚硫酸钠对硫脲的氧化分解没有明显抑制作用;当硫脲中添加亚硫酸钠后,Ecorr降低,腐蚀速率增大,电化学阻抗弧值大大降低,协同促进金的溶解;0.15 mol/L硫脲+0.15 mol/L亚硫酸钠的溶液具有最佳溶金效果。

The polarization curves and AC impedance spectroscopy of gold and platinum electrodes were measured by an electrochemical workstation to study the effect of sodium sulfite on the dissolution of gold in alkaline thiourea solution.The results showed that the corrosion potential(Ecorr)of gold with sodium sulfite was-0.776 V,which is far below that of thiourea,and that the corrosion rate was 0.014 mm/a,so it is an effective reagent for gold dissolution.For a platinum electrode,thiourea underwent irreversible oxidative decomposition under alkaline conditions,however,sodium sulfite had no significant inhibition effect on the oxidative decomposition of thiourea.With the addition of thiourea,the Ecorr decreased,and the corrosion rate increased,while the electrochemical impedance arc value is significantly reduced,synergisticallypromoting the dissolution of gold.The solution consisting of 0.15 mol/L thiourea+0.15 mol/L sodium sulfite has the best gold solubility.