| The environmental problems, i.e. the pollutions of air and water, have hazard the existence of human beings. It is the time that the governments of the nations took actions to eliminate the pollutants and protect the environment. Among the treatments of wastewater, the mineralization of dye-wastewater is thought to be of great difficult. In the past decades, considerable attention has been concentrated on the photodecomposition of organic pollutants in wastewater and it has been proved that more than 300 kinds of organics could be mineralized to inorganics (i.e., CO2, H2O, N2, Cl-, PO43-, etc) by way of photodecomposition. Therefore, the so-called photocatalytic detoxification could find promising application in water purification.In treatment of dye-wastewater by means of photocatalysis, a principal question, whether or not the thorough mineralization was performed, should be answered due to lots of yielded mid-products in the reaction. Thus, the photocatalytic decomposition of Reactive Brilliant Red X-3B in aqueous solution was studied, with anatase nano-TiO2 as catalyst. Ultraviolet-visible spectrophotometer (UV-Vis), high performance liquid chromatograph (HPLC) and mass spectrograph (MS) were applied to investigate the composite changes of solution. Moreover, the COD values of solutions were measured using dichromate titration method. The adsorptive species on the surface of catalysts were tested by Fourier transform infraredspectrameter (FT-IR). The results of UV-Vis and COD measurement indicated that, the photocatalytic decoloration and degradation processes of Reactive Brilliant Red X-3B aqueous solution were simultaneously taken place and the difficultly mineralized species were yielded in the solution. The results of HPLC and MS showed that, the difficultly mineralized species might be the sulfonaphthalene and its substitution products. Further studies should be done toconfirm the structure of the yielded mid-products.Due to the advantages of cheapness, non-toxicity and chemical stability, TiO2 has been widely used in photocatalytic decomposition of pollutants in wastewater. Unfortunately, TiO2 can only absorb the UV light with the length smaller than 400nm, because its band gap is very wide (3.2eV). In order to promote the photocatalytic activity and broaden the response range of sunlight, the narrow band gap semiconductor CdS was used to modify the nano-TiO2 in this paper. The compounds CdS/TiO2 was prepared using impregnating method. XPS and UV-Vis were applied to analyze the structure of as-prepared compound semiconductor CdS/TiO2. The results indicated that the sulfur in sample mainly existed in the form of CdS and CdSO4, and that the threshold of the sample shifted from 400 nm (3.2 eV) to 530 run (2.3 eV). With photocatalytic decolor of Reactive Brilliant Red X-3B in aqueous as model reaction, the activities of Cd/TiO2 powders were evaluated, the results indicated that, the photoactivity of CdS/TiO2 powders were higher than that of pure TiO2, and the optimum range of doping content was 0.16%-0.4%. Powder conductivity method was applied to measure the surface state energy levels of the CdS/TiO2 films. Compared with pure TiO2, the surface state energy levels of CdS/TiO2 were closer to the conduction band energy level of TiO2, which was in favor of the capture of excited electrons at the surface of samples, increased the concentration of free electrons in the samples, and finally, resulted in the promotion of photocatalytic decoloring rate of Reactive Brilliant Red X-3B in aqueous solution.In this thesis, CdS was tried to insert into the titanic acid nanotube (NTTA). It is expected to obtain a photocatalyst with higher activity, better adsorption of sunlight, and the repressing of the photocorrosion of CdS as well. In the preparing process, the nanotubed titanic acid was deep dried firstly, and the solution of CdCl2 was inhaled into nanotube utilizing the negative pressure of system secondly, the CdS-inserted nanotubedtitanic acid (SNTTA) was prepared by the reaction of H2S wi...
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