Photocatalytic Properties of Titanium Dioxide

本研究主要研究钛及相关化合物对低浓度水溶液中有机污染物的光催化降解活性。以往的研究表明，二氧化钛的活性取决于制备方法，而最好的样品是从挥发性前体中获得的。此外，添加少量(~3%)含有高价态金属的过渡金属氧化物可以促进活性表面态的形成。氧化钨或氧化钼。这种活性中心形成的增加与Lewis酸度的增加有关，这一点从与正丁胺反应的增加中可见一斑。因此，拟议的研究方向如下：1)将尝试制备具有比迄今所研究的最好的二氧化钛样品更高的光催化活性的钛；2)还将使用超临界二氧化碳制备第二组氧化物，它们涉及两个不形成块状三元相的氧化物；以及3)这项工作将扩展到与金红石密切相关的化合物家族，其中三个钛离子被两个五价离子和一个二价离子取代。含钛(IV)氧化物悬浮液中有机物的光催化氧化是一种较新的去除水中杂质的方法。所需的光激活光是太阳光或近紫外光。许多有机化合物已被证明通过这种方法被氧化成二氧化碳。它在废水和饮用水处理方面都有潜在的应用前景。漂珠上的氧化钛薄膜涂层有可能光催化漂浮在水面上的有机化合物的氧化，例如通常由漏油引起的有机化合物的氧化。本研究主要研究二氧化钛及其相关化合物对低浓度水溶液中有机污染物的光催化降解活性。

Wold This research focusses on the investigation of the photocatalytic activity of titanium and related compounds toward the degradation of organic contaminants present in aqueous solutions at low concentrations. Previous studies have shown that the activity of titanium oxide is dependent on the method of preparation, and that the best samples are obtained from a volatile precursor. Furthermore, the formation of active surface states can be enhanced by the addition of a small quantity (~3%) of a transition metal oxide containing a high formal valence state metal, e.a. tungsten oxides or molybdenum oxides. This increase in active site formation has been related to an increase in Lewis acidity as evidenced by increased reactivity with n-butylamine. The proposed research will, therefore, be directed as follows: 1) attempts will be made to prepare titanium with a higher photocatalytic activity than the best titanium oxide samples studied to date; 2) a second group of oxides will also be prepared by the use of supercritical carbon dioxide and they involve two oxides which do not form a ternary phase in bulk form; and 3)the work will be extended to a family of compounds closely related to rutile in which three titanium ions are replaced by two pentavalent and one divalent ions. %%% The photocatalytic oxidation of organic compounds in an aqueous solution containing a suspension of titanium(IV) oxide is a comparatively new method for the removal of impurities from water. The photoactivating light required is sunlight or near UV. Many organic compounds have been shown to be oxidized to carbon dioxide by this method. It has potential application in the treatment of both waste and drinking water. Titanium oxide thin film coating on floating beads has potential to photocatalyze the oxidation of organic compounds floating on water, such as those typically resulting from an oil spill. This research focusses on the investigation of the photocatalytic activity of Titaniu m and related compounds toward the degradation of organic contaminants present in aqueous solutions at low concentrations.