Sonoelectrochemical Oxidation of Aged Landfill Leachate with High-Efficiency Ti/Pani/Pdms-Ce-Pbo2 Anode

A high-performance anode containing PANI-α-PbO2 intermediate layer and PDMS-Ce-β-PbO2 outlayer was prepared by two-step electrodeposition. SEM and XRD characterization exhibited that the Ti/PANI/PDMS-Ce-PbO2 electrode has a denser surface morphology and a smaller crystal size, which also means a larger specific surface area and an increase in active sites. The results of LSV indicated that the Ti/PANI/PDMS-Ce-PbO2 electrode (1.91 V vs.SCE) has higher oxygen evolution potential than Ti/PbO2 electrode (1.74 V vs.SCE), which can effectively reduce the impact of oxygen evolution side reaction on organic matter degradation. The fitting results of EIS exhibited that Ti/PANI/PDMS-Ce-PbO2 electrode has smaller impedance (39.5 Ω). The Ti/PANI/PDMS-Ce-PbO2 electrode showed higher current efficiency in the experiment of electrochemical oxidation of gallic acid, proving that the electrocatalytic performance of the modified electrode was further improved. Therefore, the Ti/PANI/PDMS-Ce-PbO2 electrode was used for sonoelectrochemical oxidation of aged landfill leachate. The effects of three key parameters on the sonoelectrochemical system were investigated, including current density, initial pH, and ultrasonic power. The results show that the current density played the dominant role. Under the optimal parameters: 42 mA cm-2 current density, initial pH of 6, 50 W ultrasonic power, 61.9% COD removal rate was achieved. The removal rate of COD slightly decreased by about 5.5% after ten repeated experiments, demonstrating that Ti/PANI/PDMS-Ce-PbO2 electrode has good stability and potential for long-term application. The analysis results of UV-Vis and GC-MS show that the organic components of landfill leachate changed greatly after sonoelectrochemical oxidation, and the refractory substances have been effectively removed