TiO2-SiO2纳米复合介孔材料光催化降解水中微囊藻毒素

Many drinking water sources have been seriously contaminated by microcystins (MCs) in our country. The difficult problem confronted by the people working in the fields of correlative scientific research is how to highly effectively remove MCs from water. In this project, novel mesoporous anatase TiO2-SiO2 nanocomposites (including grains and membranes) with large and straight mesochannels, and high specific surface areas are scheduled to prepare using the applicant et al. improved EISA approach combined with the removal of templates in pore channels by calcination and crystallization of pore-walls under high temperatures. The ordered 2-D hexagonal mesoporous TiO2-SiO2 nanocomposites, with very unique mesoporous frameworks consisted of anatase TiO2 nanocrystals and amorphous SiO2 nanoparticles by linking mutually and partitioning off from each other, integrate the performances of excellent adsorption of SiO2 nanoparticles and highly effectively photocatalytic degradation of anatase TiO2 nanocrystals, large number of strong acid sites allowing effective hole-trapping and then prohibiting undesirable photocarrier recombination, large and straight meso-channels, and high specific surface areas as a whole, which can fast and highly effectively remove MCs from water by synergistic role. The synergistic role of highly effectively removing MCs can reach the optimal state by adjusting Ti/Si ratio and crystallization conditions of the pore-walls, the sizes of pore diameter and specific surface area. At present, the research in this aspect has not been seen in the literature. The relationship between the performances of adsorption and photocatalytic degradation and the structures and surface properties of the mesoporous photocatalysts prepared with various Ti/Si ratios under different crystallization conditions are planned to study detailedly, in order to obtain the optimal photocatalyst. The influences of mesoporous photocatalyst states (grains, membranes), solid/liquid ratios, MCs concentrations and water qualities etc on the performances of adsorption and degradation of the mesoporous photocatalysts, the degradation products and their distributions and contents are scheduled to systematically study. Micro-essences of the influences will be elucidated. The degradation intermediates, products, their distributions and changes are planned to study deeply in order to clarify the photocatalytic degradation mechanisms.

我国大量饮用水源被微囊藻毒素(MCs)严重污染，如何高效去除MCs是相关科研面临的难题。本项目拟采用申请者改进的EISA法与焙烧去除模板剂、高温孔壁晶化相结合研制新颖大孔径、直孔道、高比表面积、TiO2-SiO2纳米复合介孔材料(颗粒、膜)。该材料由锐钛矿TiO2纳米晶粒与SiO2纳米颗粒相互连接、相间组成,集吸附与光催化降解性能、有效分离光生空穴的强酸中心、大孔道、高比表面积于一身、协同作用，可高效去除水中MCs。调节孔壁钛/硅比、晶化条件，孔径与比表面积大小，可使上述协同作用达到最佳状态。目前这项研究尚未见报道。拟详细研究各种催化剂结构、表面性质与性能的关系，研制出性能最佳光催化剂。系统研究光催化剂形态（颗粒、膜）、固/液比、MCs浓度、水质条件等对催化剂吸附与降解MCs性能、降解产物及其分布与含量的影响，阐明其影响的微观本质。深入研究降解中间物、产物及其分布与变化情况，阐明降解机理。

我国大量饮用水源被微囊藻毒素(MCs)严重污染，如何高效去除MCs是相关科研面临的难题。本项目采用申请者改进的EISA法与焙烧去除模板剂、高温孔壁晶化相结合，制备大孔径、直孔道、高比表面积TiO2-SiO2纳米复合介孔材料(颗粒)，然后以此为母体采用抽提SiO2的方法在其孔壁内造二次孔，研制出孔道三维互通的TiO2-SiO2介孔材料。此类材料可高效去除MCs。该方法简单、温和、易重复。详细研究了催化剂结构、表面性质等与吸附和光催化降解microcystin-LR (MC-LR) 性能的关系。研究了•OH自由基的瞬时稳态浓度、MC-LR被降解的最终产物等。结果表明，研制的光催化剂降解MC-LR的活性非常高(2.57 min-1)，该活性是其母体的2.8 (0.903 min-1)倍，是Degussa公司商业化生产的P25光催化剂的7.2 (0.357 min-1)倍。孔道互通TiO2-SiO2介孔材料产生的•OH自由基瞬时稳态浓度相当高 (26.73 × 10-14 M)，该浓度是其母体的3.6 (7.453 × 10-14 M)倍。此类催化剂还可快速将MCs及其降解中间物彻底矿化为CO2和H2O等。此外，孔道互通TiO2-SiO2介孔材料对其它有机污染物（如染料）也展现出极高的降解性能。如此高活性的光催化剂在之前的文献中尚未见报道。同样重要的是，TiO2-SiO2介孔光催化剂具有相当的稳定性和重复使用性。本项目研制的催化剂具有很好的、广泛的应用前景。而且，这项研究的基本原理将为具有独特光催化性能的其它金属氧化物基介孔材料的合理设计和制备提供了崭新视角。 . 采用表面活性剂与无机物前驱体同步自组装法(简称：自组装)，结合焙烧去除模板剂、高温孔壁晶化过程分别于载玻片、氧化铝陶瓷片和单晶硅片表面合成出介孔TiO2膜、TiO2-SiO2纳米复合介孔膜。膜的介孔结构有序度、热稳定性均高，膜厚在一定范围内可控。光滑面上的膜层比粗糙面上的更均匀，而粗糙的表面更有利于晶体产生。膜层越薄，裂纹越稀疏，与基底结合相对较牢固。本方法可重复，条件可控。本研究为介孔TiO2和TiO2-SiO2纳米复合介孔材料未来的实际应用积累了良好的基础数据。