石墨电极上硫化钠的阳极氧化机理探索

电解硫化氢气体的碱性吸收液（Ｎａ２Ｓ表示）产生单质硫和氢气的研究是治理硫化氢废气的一种新方法［１ -７］，较之Ｃｌａｕｓ法有许多优点［３，４］，这对环境保护和资源回收均具有重要的实际意义．文献对硫化物水溶液电化学氧化机理的研究主要着重于在某些贵金属阳极上，包括某些硫化矿的湿法冶金反应过程的研究［８，９］，光电化学电池中使用多硫化物的研究［１０ -１３］，以及硫化物电解时产生单质硫的电催化活性研究［１４］等 ;但在石墨阳极上硫化物电化学氧化机理的研究报导却很少［３，４］．本文研究在石墨阳极上硫化钠水溶液…

Investigation of Anodic Oxidation Mechanism of Na2S Solution on Graphite Electrode

Electrochemical behavior of aqueous sodium sulfide solution at graphite anode,under the condition of different concentrations of Na2S and different temperatures,has been investigated by cyclic voltammetry and chronopotentiometry.The results show that the anodic oxidation of aqueous sulfide solution is irreversible and that polysulfides are formed in rate-determining step of the anodic oxidation.With the increase of electrolytic temperature,potentials corresponding to anodic peaks shift to more negative and those corresponding to cathodic peaks shift to more positive,which indicates that the elevating of temperature is favorable to both oxidation of the sulfide and reduction of products polysulfides or elemental sulfur.Rate constants ks of standard electrode reaction for anodic oxidation of Na2S solution are between 10－ 4.08～ 10－ 4.35cm· s－ 1 at 70℃ .Chronopotentiometric studies show two potential peaks in time-potential curve for a smaller current density value.The potential peaks may result from a self-catalytic effect taking place due to both dissolution of elemental sulfur by S2－ ,HS－ and ,and transition reactions among polysulfides.The potential peaks disappear with the increasing of anodic current density.