Preparation Of High Stability PbO₂ Electrode And Its Electrocatalytic Oxidation Of Typical Refractory Organic Pollutants

In this paper,the crystal facet of PbO2 coating was controlled by inducing surfactants sodium dodecyl sulfate(SDS)and cetyltrimethylammonium bromide(CTAB)in the electrodeposition process,and high stability PbO2(SDS)and PbO2(CTAB)electrodes were obtained.The electrocatalytic oxidation ability of the prepared lead dioxide electrodes were evaluated by degrading typical refractory pollutants tetracycline(TC)and Congo red(CR).The conclusions were as follows:(1)In the process of electrodeposition,adding SDS and CTAB induced preferred orientation of crystal facet and increased the exposure of the high index crystal facet β(301),thereby raising the oxygen evolution potential of the electrodes.In addition,the modified lead oxide crystal size was reduced,and the morphology of the coating was smooth and compact,which made the accelerated life of PbO2(SDS)and PbO2(CTAB)electrodes longer than PbO2 electrode by 81 h and 147 h respectively,while the amount of lead ion dissolution was reduced by 43%and 55%respectively.(2)Using PbO2(CTAB)electrode as anode to degrade TC.Under the optimum conditions,after 180 minutes of degradation,the COD removal rate of the wastewater was 69.70%and the electrical energy per order was 37.03 kWh·m-3.The degradation reaction of TC by PbO2(CTAB)electrode belonged to indirect oxidation.TC was oxidized into small molecular substances through carbonylation,demethylation,deamination(-NH2)and ring opening reaction,and finally mineralized into harmless H2O and CO2.(3)CR was degraded with PbO2(CTAB)electrode as anode.Under the optimum conditions,after 180 minutes of degradation,the COD removal rate of wastewater was 42.56%and the electrical energy per order was 44.82 kWh·m-3.The degradation reaction of CR by PbO2(CTAB)electrode belonged to indirect oxidation.The strong chromogenic azo double bond in CR molecule is oxidized by the active free radical,so as to decolorize CR.However,the electrode cannot completely degrade the aromatics of CR.Therefore,the modified lead oxide electrode PbO2(CTAB)studied in this paper not only has high stability,but also realizes the efficient degradation of organic pollutants.