【作者】 杨海明；

【导师】 柳丽芬； 张兴文；

【作者基本信息】 大连理工大学 ， 环境工程， 2006， 硕士

【摘要】 半导体光催化材料是近年引起众多学者关注的一种新型功能材料。光催化剂具有在室温、常压下将光能转变成化学能的能力,因而,光催化氧化成为处理废水中污染物的一种有效的方法。由于TiO₂具有较高的稳定性、活性、低成本、无毒性、难溶于酸和碱等特点,成为光催化剂研究的热点。将二氧化钛光催化技术应用于废水的处理目前还有两个亟待解决的问题:其一,在利用纳米粉体二氧化钛光催化降解污染物时存在着二氧化钛易团聚、不利于回收和重复利用、易造成二次污染等阻碍实际应用的问题;其二,TiO₂禁带宽度大（3.2eV）,只能利用太阳光中的仅占太阳光能3-4%紫外线部分。这使TiO₂作为光催化剂在实际应用中难以大规模推广。 在本研究中,针对上述两个问题,利用钛酸四丁酯作为钛源,采用溶胶-凝胶法成功地制备了负载在沸石ZSM-5表面的二氧化钛光催化剂,克服了其团聚和难于回收并重复利用的问题;同时,采用负载贵金属铂和掺杂非金属元素氮对TiO₂进行掺杂改性,将TiO₂光谱响应范围扩展到可见光区。并考察了这些催化剂的光催化氧化去除水中氨氮的效果。获得了TiO₂/ZSM-5样品的最佳热处理温度450℃、TiO₂最佳负载量30.4wt.%以及催化剂的最佳用量1g/L。相应的氨氮去除率达到40%,此时TiO₂为锐钛矿相,部分通过化学键与沸石结合。采用光沉积法制得Pt/TiO₂/ZSM-5光催化剂。Pt的负载抑制了光生电子和空穴的复合,将TiO₂光谱响应范围扩展到可见光区,使光催化剂的活性得到一定提高,增大了太阳光的利用效率。而Pt负载量则存在一个最佳负载量,为1.5wt.%。Pt（1.5wt.%）/TiO₂（30.4wt.%）/ZSM-5催化剂具有较好的可见光活性,在日光照射、空气曝气条件下,处理60mg/L氨水,120min后氨氮和总氮去除率分别为56.9%和37.4%。 此外,本文还制备了掺氮介孔TiO₂/MCM-41光催化剂。利用XRD、IR和UV-VIS等方法对催化剂进行了表征。TiO₂与MCM-41发生了化学键合,TiO₂不易脱落,催化剂重复使用5次活性变化不大;氮元素的掺杂使催化剂具备了良好的可见光活性。在日光照射、空气曝气条件下,处理60mg/L氨水,120min后氨氮和总氮去除率分别为49.78%和36.04%。更多还原

【Abstract】 It has been widely studied to photocatalytically degrade and mineralize pollutants in wastewater using semiconductors at normal temperature and pressure. Photocatalysis has become one of the most effective methods to degrade various kinds of pollutants. Titanium dioxide, an important photocatalyst for its higher stability, activity and cheapness, did not dissolve in the acid and alkali conditions. There are two main disadvantages that seriously limit the application of titanium dioxide. First powder catalysts are difficult to reuse. Second, large scale application of titanium dioxide as photocatalyst is hampered by the fact that it absorbs only a very small part of solar light （ultraviolet only 3-4%） due to its wide band-gap of 3.2eV.To overcome these two disadvantages, this paper studied preparation of titanium dioxide photocatalyst supported on zeolites with tetrabutyl titanate as titanium source by a sol-gel method. The chemical bond interaction was achieved between titanium dioxide and zeolites. This facilitated an easy recovery and resue of the catalyst. Photocatalytically deposited Pt on TiO₂/ZSM-5surface and the Nitrogen-doped TiO₂ were prepared to increase the catalyst activity in visible light area, and the efficiency in solar light utilization. The activity of these catalysts in photocatalytic oxidation and removal of ammonia from water were investigated. The influence factors such as the amount of supported TiO₂, the calcinating temperature and the dosage of photocatalyst were further studied. The results showed that the best amount of TiO₂ was about 30.4wt.%, the best calcinating temperature 450℃（anatase.was formed）, and the best dosage of photocatalyst was 1g/L. Pt photocatalytically loaded on the TiO₂/ZSM-5 surface prevented the recombination of photo-induced electrons and holes, besides widening the responding range to light in visible area, and enhanced the photocatalytic activity with an optimal value at 1.5wt.%. Pt（1.5wt.%） /TiO₂（30.4wt.%） /ZSM-5 had high photocatalytic activity. The best ammonia and TN removal （120min） under solar light with air sparging reached 56.9% and 37.4% respectivelyTypical mesoporous silica MCM-41 and nitrogen doped TiO₂/MCM-41 was prepared by a sol-gel method then charactered using XRD, IR and UV-VIS. Activity of TiO₂/MCM-41 was stable after five times reuse;nitrogen-doped TiO₂/MCM-41 had high photocatalytic activity under solar irridation. The best ammonia and TN removal （120min） under solar light with air sparging reached 49.78% and 36.04% respectively.更多还原