Efficient degradation of phenolic wastewaters by a novel Ti/PbO2-Cr-PEDOT electrode with enhanced electrocatalytic activity and chemical stability

Novel Ti/PbO2-Cr-PEDOT electrodes were prepared by electrodeposition for electrochemical degradation of phenolic wastewater. The electrodes were characterized by XRD, SEM-EDS, XPS, and FT-IR to study the crystalline, surface morphology, elements distribution, and microstructure of the electrodes. A flat and compact interface was obtained with Cr and PEDOT doping into beta-PbO2 plate by electrodeposition method. The linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were conducted to explore the electrochemical performance of the prepared electrodes. The Ti/PbO2-Cr-PEDOT electrode exhibited a higher oxygen evolution potential (OEP, 2.53 V vs SCE) and a lower charge transfer resistance compared with Ti/PbO2. Phenol degradation efficiency of 100% and TOC removal rate of 95.02% were achieved in the electrochemical degradation of phenol within 120 min. The optimal process parameters (phenol concentration = 1000 mg.L-1, electrolyte concentration = 4.0 g.L-1, current density = 15 mA.cm(-2) and electrode distance = 3 cm) in the process of electrochemical oxidation of phenol wastewater were explored. Active species trapping experiments proved that center dot OH radicals played an important role in the electrochemical system. Furthermore, the electrode also showed high activity for the degradation of other phenolic wastewaters such as phloroglucinol (eta(DEP) = 100%), bisphenol A (eta(DEP) = 97.17%) and p-chlorophenol (eta(DEP) = 89.77%) within 60 min. A possible degradation pathway was proposed based on the intermediate products determined by HPCL. The Ti/PbO2-Cr-PEDOT electrode showed excellent stability with only 3% loss of degradation efficiency (eta(DEP )= 96.95%) after recycling tests for 5 times. These results suggest that Ti/PbO2-Cr-PEDOT is a promising electrode for electrochemical degradation of phenolic wastewaters.