Preparation of efficient titanium containing photocatalysts by recycling inorganic sludges

The natural resources on the earth are overused and consumed rapidly. Taiwan is short of nature resources and most resource was imported from oversea. Thus, how to efficiently recycle the resource become one of the most important issue in the recent years. In this work, different methods to fabricate TiO₂ supported on waste sludge (ESF) are investigated. Furthermore, various nitrogen sources are used to prepare the N doped TiO₂-ESF composites. In the experiments, the loading of TiO₂ onto ESF to prepare well dispersed active sites on ESF in order to enhance the efficiency in the process of synthesis TiO₂-ESF composite. In addition, the effects of different synthesis methods and the amounts of ESF addition are discussed. XRD results show that TiO₂ crystal structures still remain anatase phase after heat treating at 723 K whether the ESF is added or not. Among all the photocatalysts, the TBE-1.5 has the best photocatalysis efficiency under simulated sunlight and visible light. In the doping nitrogen experiments, the different nitrogen sources (NH₄OH, Ethylenediamine, Urea) are used to synthesize nitrogen doping TiO₂. The results show that NH₄OH as the nitrogen source have best photocatalysis efficiency. Afterwards, the NH₄OH is used as the nitrogen source to synthesize TiO₂ESF doping nitrogen (N₂TBE-1.5). The composites are characterized by TEM, UV-vis, BET, XPS analysis. The results indicate that the preparation of N doped TiO₂ESF photocatalysts is successful. Under visible light situation, the photocatalysis efficiency of MB can reach 39.6% which is better than commercialized photocatalysts P25 (3.6%).