Preparation And Dye Wastewater Treatment Of Nb/PbO₂Electrode

In the wastewater treatment technology, the electrochemical asenvironmentally friendly technology has widely attention. In this paper, metalniobium is used as the electrode substrate to prepare Nb/PbO2that wasmodified by the method of oxide doped. In addition, electrochemicalperformance and the effect on the degradation of dye wastewater were studied,which provided the important basis for the optimization of electrode materials indye wastewate degradation.Nb/PbO2electrode and ZrO2-doped Nb/PbO2electrode were prepared byelectrodeposition and used as an anode for the electrochemical degradation ofmethyl orange (MO). The microstructure and electrochemical properties ofNb/PbO2electrode were investigated using scanning electron microscopy (SEM),X-ray diffraction (XRD), cyclic voltammograms. The effects of electrolyte,temperature, current density, and pH on decolourisation efficiency were alsostudied. The comparison of two kinds of electrode were investigated usinglinear-sweep voltammetry, electrochemical impedance spectroscopy and cyclicvoltammograms. Results revealed that the Nb/PbO2electrode surface is dense, uniform andmainly composed of β-PbO2with a small amount of α-PbO2, as well as it hasgood catalytic effect on degradation of methyl orange; at initial pH6.0,45oCtemperature,50mA·cm2current density,0.08mol·L1electrolyte (Na2SO4)concentration, and30min electrolysis time, the colour removal efficiency andCOD removal reached99.6%and72.6%, respectively. The reaction mechanismof electrocatalytic MO degradation by Nb/PbO2electrode mainly involved theOH radical attack of parent molecules, and the degradation followedpseudo-first-order kinetics.ZrO2-doped Nb/PbO2electrode has a dense and rough surface and a smallsize crystal particles. Nb/ZrO2+PbO2electrode surface is mainly composed ofβ-PbO2with a small amount of α-PbO2and ZrO2.Electrochemical performancetests show that Nb/ZrO2+PbO2electrode has higher oxygen-evolution potential（2.03V）and lower charge-transfer resistance, as well as higher electrocatalyticactivity（3.22mA）in the degradation of organic materials than Nb/PbO2. Thecolour and COD removal efficiency was up to92.3%and79.5%, respectively.Electrocatalytic MO degradation processes by Nb/ZrO2+PbO2are irreversibleand controlled by diffusion.