Electrocatalytic Degradation Of Aromatic Organic Pollutants In Aqueous Solutions By β-PbO₂Composite Electrodes

Ti-based β-PbO₂electrode, Co₃O₄/β-PbO₂composite electrode andCeO₂/β-PbO₂composite electrode were successfully prepared usingelectrodeposition, and characterized by scanning electron microscopy （SEM）,X-ray diffraction （XRD）, anode polarization curves and accelerating life test. Theefficiency of electrocatalytic degradation of p-nitrophenol （p-NP） or bisphenol A（BPA） by using β-PbO₂as anode were examined, the results showed that theproduce-oxygen voltage, electric capability, stability and life of electrode could beimproved by doping a certain amount of Co₃O₄or CeO₂.When p-nitrophenol was60mg/L, the applied voltage was20V, the electrodespacing was7cm, initial pH was5, supporting electrolyte of NaCl was0.025mol/Land electrolyzing1.5h, the removal rate of p-NP and CODCrcould be diminishedup to99%and87.5%, respectively. And the degradation followedpseudo-first-order kinetics.Compared the electrocatalytic activity of β-PbO₂electrode, Co₃O₄/β-PbO₂composite electrode and of CeO₂/β-PbO₂composite electrode.The results showthat: after1.5h electrolysis at bisphenol A initial concentration of20mg/L, appliedvoltage of20V, electrode spacing of7cm, initial pH of5, and NaCl concentrationof0.020mol/L, the removal efficiency of CODCrcould be diminished up to90.6%,92.2%and95.7%, respectively.The degradation followed pseudo-first-orderkinetics.With BPA initial concentration of20mg/L, plate spacing of7cm, pH=5,applied voltage of20V, NaCl supporting electrolyte concentration of0.020mol/L,and electrolysis time of2.5h, main organic degradation products identified byGC–MS analysis were1,2-dichloro-pentane （54%）,4-Heptanol （26%） and1,2-dichloroethane （20%）. In addition, after electrochemical decomposition for2.5h, TOC decreased by62.1%.The degradation products of BPA mainly consisted ofsmall molecular straight chain compounds, CO₂and H₂O.The preliminary mechanism of electrolysis on lead dioxide anode was alsodiscussed. Hydroxyl was formed during the oxidation of water on lead dioxideelectrode and participates in the degradation of organic substance.