染料敏化TiO2纳米薄膜的光催化氧化机制及其在水处理中的应用

In order to solve the issues of nano-particle system in photo-catalytic wasterwater treatment, dye-sensitized TiO2 nano-crystalline film will be used absorbing visible light to photo-degrade organic pollutants dissolved in water. Firstly, dye molecules must be selected and modified to suit the new system. Then, TiO2 nano-particles will be shaped and sintered to form the porous nano-crystalline film, which could inhibit aggregation between nano-particles, therefore to enlarge the reactive surface and to simplify the separation process. The unique properties of such film will be systematically characterized, the correlation among which will be investigated. In association with photo-degradation study of organics, the microstructure of the film will be further modified to inhibit the interfacial recombination between the photo-induced charge carriers, which could eventually improve the charge separation efficiency and photon-to-electron conversion efficiency for the new system. Moreover, the film stability during photo-oxidation of organics will be studied and improved for better sustainability and recyclability. Reaction conditions will also be investigated, and then be modified for better photo-catalytic performance. In addition, the transformation of intermediates and the pathway of organics during photo-degradation need to be elucidated. It is of particular importance to identify the active oxidizing species and to understand the dynamics during their formation. Finally, the mechanism how the dye-sensitized film photo-degrades organics by visible light will be unveiled. Based on these results, theoretical model will be established, reactor will be redesigned, and processing parameters will be modified. Eventually, the new visible-light-driven photo-catalytic oxidation process for removing organic pollutants from wastewater will be developed.

针对传统纳米颗粒光催化水处理体系存在的问题，将染料敏化TiO2纳米薄膜与水处理相结合，基于其光催化氧化特性利用可见光降解水中有机污染物；筛选优化适于光催化水处理的新型染料，利用其化学键合对TiO2纳米颗粒修饰改性，以增强其可见光吸收；将纳米颗粒集成连接制成介孔薄膜，以减少团聚、增加催化表面积、简化分离工艺；表征薄膜微观结构，结合有机污染物降解实验，探明特性参数之间关系；优化微观界面结构，减少载流子界面复合，提高电荷分离与光电转化效率；改善薄膜理化稳定性，以实现循环利用；优化反应条件，提高光催化降解效率；解析有机污染物在反应中的迁移转化规律与降解途径；明确活性氧化成分的组成与形态，探明其形成机制与反应动力学，揭示界面反应机理；建立理论模型，设计反应器，优化工艺参数，构建基于染料敏化纳米薄膜的光催化氧化水处理工艺体系，实现利用太阳能高效降解水中有机污染物的低能耗清洁环保新思路。

研发制备了多系列具有全可见光谱响应的新型纳米复合光催化材料，探明了污染物降解途径与界面反应机理，建立了新型光催化氧化反应体系设计原理，优化了高效光催化氧化处理技术工艺参数。.本项目取得的成果主要包括：.（1）采用简单的煅烧方法制备了TiO2/g-C3N4光催化剂，选择对乙酰氨基酚（AAP）作为模型污染物，测试了TiO2/g-C3N4光催化剂在PS体系下的光催化降解效率，证实了TiO2/g-C3N4-PS光催化体系具有很强的非选择性去除微污染物的能力。.（2）利用g-C3N4和D35染料互补共吸收能力，制备的D35-TiO2/g-C3N4纳米复合材料具有高达675 nm的准全可见光吸收，电子同时从D35和g-C3N4注入到TiO2协同活化过硫酸盐高效产生活性氧化物质。.（3）开发了新型TiO2-x/rGO-PS-Vis水处理体系，该工艺利用氧空位自掺杂TiO2偶联石墨烯纳米复合材料高效活化过硫酸盐，在可见光照射下增强了微污染物的氧化降解效果。.（4）通过简单的合成路线成功实现了具有增强可见光驱动光还原能力的新型CDs-N-TiO2-x纳米复合材料。CDs-N-TiO2-x纳米复合材料由于CDs负载、Ti3+/Ov和氮共掺杂的影响，显著提高了可见光的利用率和载流子的分离。.（5）制备了具有自漂浮性的可见光吸收N-TiO2-x/rGO@纤维素纳米杂化光催化剂。其在可见光照射下具有高效的污染物降解能力。这项工作解决了材料的回收/可重用性问题，对于廉价大规模制造多功能可见光光催化剂用于环境修复应用具有重要意义。证实了TGNF@TOBC/PS/Vis 系统在可见光驱动的光催化处理废水中难降解有机微污染物中的实用性和有效性。.研究成果将为我国环境污染物治理领域探索一条新的技术路径，对推动新型光催化材料与光催化氧化技术规模化应用与发展具有技术引领作用。研究成果不仅在理论上有重要意义，也为新体系在水处理应用中的可行性提供了科学依据，具有广阔的实用价值。