Electro-activation of peroxymonosulfate by β-PbO2 partial filling/covering TiO2 nanotube arrays anode for alkaloid berberine degradation: Performance, mechanism and practicability

An interlocking T-shape structure was built by uniform filling beta-PbO2 crystalline inside the trace Ti3+ self-doping TiO2 nanotube arrays (TNAs) channels and depositing the cauliflower-like beta-PbO2 clusters on its upper surface through a facile current pulse deposition method. We elaborated the interfacial engineering strategy for generating compact oxide layers at TNAs bottoms and growing beta-PbO2 crystalline from the selectively conductive TNAs bottoms. Different characterization techniques and electrochemical analyses were conducted to charac-terize the morphology, structure, and electrochemical property of the beta-PbO2 partial filling/covering TNAs (beta-PbO2/TNAs/Ti) materials. We also systematically investigated and elucidated the performance and mecha-nism of beta-PbO2/TNAs/Ti anode activated peroxymonosulfate (PMS) system via berberine removal/mineraliza-tion, reactive oxygen species (ROS) identification/contribution, intermediates analysis, energy consumption and practical applicability estimation. Results illustrated that filling beta-PbO2 inside TNAs can efficiently improve the directional electron-transfer efficiency, oxygen evolution over-potential, tolerance to the varied water matrices and service lifetime of beta-PbO2/TNAs/Ti anode activated PMS system. The ROS including center dot OH, SO4 center dot- and O-1(2) that generated from PMS electro-activation are responsible for efficient berberine degradation through two pathways. This study will provide a general approach to construct the versatile tube-filled TNAs-based materials for wide applications in water/wastewater treatment.

Automated summary

An interlocking T-shape structure was constructed by filling β-PbO2 crystals inside Ti3+ self-doping TiO2 nanotube arrays (TNAs) channels and depositing cauliflower-like β-PbO2 clusters on its upper surface. The performance and mechanism of the β-PbO2/TNAs/Ti anode activated peroxymonosulfate (PMS) system were investigated and elucidated. Results showed that filling β-PbO2 inside TNAs can improve the electron-transfer efficiency, oxygen evolution over-potential, tolerance to water matrices, and service lifetime of the system.