有机污染物在Magnéli相氧化钛上的电化学氧化效能与机制

Electrochemistry offers an effective approach for treatment of non-biodegradable wastewater. The engineered applications of electrochemical technology have long been limited by electrode materials, in terms of the incompatibility of conductivity, activity, stability, and economical factors. Magnéli-phase titanium oxides are the representative of a series of active substoichiometric titanium oxides, whose special crystalline structure gives rise to high conductivity, high stability and high activity, making it a promising electrode material for potential application in electrochemical wastewater treatment. The present project will focus on the mechanisms for electrochemical oxidation of organic pollutants on the surface of Magnéli-phase titanium oxides electrode as the key scientific problem. The main works to be performed in this project include the preparation and characterization of Magnéli-phase titanium oxides, and the first-principle calculation based on density functional theory (DFT). Afterwards, efforts will be emerged to uncover the electrochemical mechanisms of •OH formation by water oxidation and its statement and change on the electrode surface. This will build a basis for further identification of the structure-activity relationship between the electric and surface structure and oxidation of organic pollutants. The last task is to investigate the impact of electrochemical performances by the key factors such as electrode potential, solution pH, organic pollutants, co-existing cations and anions. This study not only suggests the fundamental mechanisms for oxidation of organic pollutants on Magnéli-phase titanium oxides electrode, but also provides new strategies and methods to develop high-activity, high-stability, sustainable electrode materials and electrochemical process for wastewater treatment.

电化学法是处理难降解有机废水的有效方法之一。电极材料在导电性、活性、稳定性和经济性之间的矛盾制约着电化学技术的应用。Magnéli相氧化钛是一类非化学计量钛氧化物的通称，具有良好的导电性、抗腐蚀性和电化学活性，在污水处理中有广阔的应用前景和潜在的研究价值。本项目围绕“有机物在Magnéli相氧化钛表面氧化的电化学机制”这一关键科学问题，开展电极材料制备、表征及第一性原理的研究；揭示在水分子氧化生成•OH的电化学机制及其在电极表面的赋存状态和演变规律，进而识别Magnéli相氧化钛的电子和表面结构与有机污染物在其表面氧化分解的构效关系，探索关键影响因子如电位电流、溶液pH、有机物种类浓度、共存离子的影响机制。本研究不但为深入认识Magnéli相氧化钛在有机物氧化过程中的作用规律和优化电化学体系设计与运行参数提供了理论依据，而且为发展高效、稳定、绿色的废水处理工艺提供了新思路和新方法。

电化学废水处理方法具有高效、绿色、易于集成和自控等特点，特别是废水中的无机盐能够作为电极反应的电解质，使得电化学法(电化学高级氧化法、生物电化学法、光电化学法等)在高盐废水处理中具有独特优势。然而，电化学处理的工程化应用仍面临诸多瓶颈，如电极制备工艺复杂、成本高以及长期运行过程中由电极腐蚀、污染、钝化导致的性能下降等问题，对工业废水电化学处理的电极结构与界面作用原理和工艺提出挑战。为了解决这些问题，本项目提出了新型亚氧化钛陶瓷电极制备原理与方法，发现了氧空位形成的剪切面是导电关键机制，钛的多价态共存结构可实现高氧化性中间产物活性和电极稳定性的双向提升，在中试水平上实现了工业废水的深度净化。揭示了电极界面多物理场耦合协同作用机制，发现并提出了电场分布边界效应、浓度场限域效应和焦耳热效应，发展了寒区冬季低温难降解废水电催化原理与工艺模式。阐明了多孔电极的限域效应、传质的微观流体动力学机制和电极钝化机理与防控措施，实现了多种废水的高效处理。