煤基薄膜泡沫炭复合纳米二氧化钛的构建及其吸附降解含酚废水研究

Semiconductor-assisted photocatalytic oxidation process is a green technology with no secondary pollution for degradation of pollutants in wastewater. However, the use of metal oxide semiconductor powders represented by TiO2 in aqueous solution presents significant technological drawbacks related to low recovery and stability. This project proposes a novel photocatalytic material with high efficiency for adsorption/degradation of phenols in wastewater, that is, coal-based film carbon foam-TiO2 nanocomposites. The multi-size porous film carbon foams (FCF) are prepared with loose medium component which is separated from raw coal by all-components group separation as raw material, using a series of processes such as solvent extraction, carbonization and activation. The three-dimensional interconnected film structure can reduce the diffusion resistance, increase the light transmission and the solution/catalyst contact surface, while the micropores/mesopores can effectively adsorb organic pollutants. Then TiO2 is immobilized onto FCF as support with different immobilization methods to form composite photocatalysts. The activities of photocatalytic degradation of phenolic compounds in wastewater are studied over TiO2/FCF. The adsorption/photodegradation cooperative effects and structure-activity relationship of the composite photocatalysts are investigated in order to improve their activity and stability of cyclic use. This project will provide theoretical guidance and technical support for preparation of supported semiconductor photocatalyst and its industrial application, and also provide a new idea for high value-added utilization of coal product based on the all-components group separation.

半导体光催化氧化过程是一种理想的绿色、无二次污染的水污染治理技术。然而以TiO2为代表的单纯半导体金属氧化物在水溶液中存在不易回收、稳定性低等缺点。本项目提出一种可用于吸附降解含酚废水的新型高效光催化材料-煤基薄膜泡沫炭复合纳米TiO2材料。以煤全组分分离得到的疏中质组为原料，采用溶剂抽提、炭化、活化等方法和工艺构建多级孔结构薄膜泡沫炭，其三维网状薄膜结构可减小扩散阻力、增大光线利用率并增加溶液/光催化剂接触表面，丰富的微孔/中孔结构可有效吸附有机污染物。采用不同的负载方法将纳米TiO2固定于薄膜泡沫炭载体上形成复合光催化剂，进行废水中酚类有机物的光降解研究。通过研究吸附/光催化协同机制及催化剂构效关系，提高复合光催化材料的活性和循环使用稳定性，为负载型光催化剂的制备及工业化应用提供理论依据和技术支持，同时也为煤基于全组分分离的产品实现高附加值利用提供一种新思路。

半导体光催化氧化过程是一种理想的绿色、无二次污染的水污染治理技术。然而以TiO2为代表的单纯半导体金属氧化物在水溶液中存在不易回收、稳定性低等缺点。本项目以新型煤基薄膜泡沫为载体，通过负载具有可见光响应特性的非金属掺杂TiO2，解决催化剂分离回收困难的问题，并提高催化剂的光利用效率。本项目首先研究了新的非金属N/F掺杂TiO2的制备方法，然后以煤疏中质组为原料通过炭化、活化得到多级孔结构薄膜泡沫炭，最后将纳米非金属掺杂TiO2固定于薄膜泡沫炭载体上形成复合光催化剂，用于吸附降解含酚废水研究。本项目主要考察了TiO2合成方法、非金属掺杂方法及掺杂量、泡沫炭载体的活化方法以及掺杂TiO2的负载量等对复合光催化剂在模拟太阳光条件下（PL-03氙灯光源，500 W）光降解性能的影响，考察了复合光催化剂的吸附-降解协同作用和循环使用稳定性。.结果表明，采用低温回流法以尿素为氮源，N：Ti=3，600 oC煅烧获得的N-TiO2禁带宽度为2.77 eV，在模拟太阳光下6 h内苯酚降解率为92.4%。对疏中质组炭化得到的薄膜泡沫炭采用水蒸汽活化，活化温度800 oC，活化时间50 min时制备的层次孔泡沫炭，比表面积为388 m2/g，中孔率为26.7%。以其为载体，浸渍法负载35 wt% N-TiO2制得的复合光催化剂，在模拟太阳光下2 h内对苯酚的降解率达93%。连续循环使用4次后，对苯酚的降解率仍维持在90%。.与商业P25对比，纯TiO2、N-TiO2和复合光催化剂N-TiO2/FC在可见光照射下6 h内对苯酚的降解效果均比P25好，降解率分别为10.8%、24.9%和68.6%。N的掺杂和多级孔泡沫炭的复合均提高了二氧化钛在可见光下对苯酚的光催化活性。本项目实现了高效煤基薄膜泡沫炭复合N掺杂纳米TiO2光催化剂的制备，具有潜在的工业化应用价值。