Preparation Of Modified Lead Dioxide Electrode And Research Of The Electro-catalytic Properties

Four anodes: Ti/PbO₂, Ti/Fe-PbO₂, Ti/SnO₂+Sb₂O₃ and Ti/SnO₂+Sb₂O₃/Fe-PbO₂ were prepared.The electrodes were characterized with scanning electron micrograph (SEM), X-ray diffraction (XRD), anodic oxygen evolution potential testing (LSV), cyclic voltammetry (CV), accelerated service-life testing and inductively coupled plasma (ICP) to evaluate the properties. The electro-catalytic activity and conductivity of our laboratory-made electrodes were explored through electrochemical oxidation of phenol simulated wastewater. The experimental results showed that, among four anodes, our laboratory-made modified lead dioxide electrode Ti/SnO₂+Sb₂O₃/Fe-PbO₂ was a novel anodic material with relatively high oxygen evolution potential and catalytic activity, low cell voltage and long service-life. The intermediate layer of the electrode contained of SnO₂+Sb₂O₃, while the outside layer mainly contained ofβ- PbO₂ with a tetragonal structure. The outside layer possessed small-size crystal particles and a uniform, compact crystalline structure, which favored to improving the electrode's catalytic activity. The stability and electro-catalytic activity of the electrode were improved greatly by introducing the intermediate layer and iron doping.At the same time, the influence factors of phenol removal rate such as current density, initial phenol concentration, supporting electrolyte Na₂SO₄ concentration, supporting electrolytes'types, temperature, and pH value were investigated systematically. It was found that the optimal operating condition of electrochemical oxidation of phenol were a current density of 10mA/cm2, a initial phenol concentration of 100mg/L, a supporting electrolyte concentration of 0.05mol/L, a temperature of 25℃and a pH value of 12 in this study. Under such operation condition, a phenol removal rate of 97% can be obtained after 5h degradation. For the three electrolytes studied, the sequence of the phenol removal rate was NaCl>Na₂SO₄>NaNO₃. The Cl- ion existed in the solution can transform to Cl2, HClO and ClO- by oxidation, which can indirectly oxide phenol. The effect of·OH on phenol electrocatalytic degradation was investigated by using isopropanol as·OH capture. The result of the study showed that electrochemical oxidation of phenol was mainly of indirect oxidation and the hydroxyl radicals (·OH) electro-generated on the electrode surface during the electrolysis process played a significant role for the oxidation of phenol.In addition, electrochemical reactor was designed in order to explore the possibility of modified electrode in practical industrial application. The results indicated that the electrochemical reactor can effectively degrade phenol simulated wastewater. The phenol removal rate of 98% and COD of 72% can be reached. Running of the electrochemical reactor was stable and safety.