Photocatalytic oxidation of NOX over TiO₂ containing cement based materials

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2013
Bayar, İbrahim
The scope of this thesis was to construct a NOX analysis test system based on ISO-22197:2007(E) standard that can monitor NO oxidation ability of photocatalytically active surfaces. The activity of cement based materials containing TiO2 on photocatalytic oxidation of NOX was observed in this test system. In addition, the experimental validity of the ISO-22197:2007(E) standard was verified. Improvements and modifications are recommended. The method was tested on TiO2 samples coated on the glass, coated on the grout and prepared in the grout samples. Doctor blade method and sol-gel method was used on the glass coating. Experiments indicated that TiO2 on the surface of the grout exhibits more catalytic activity in oxidation of NO than the same amount of TiO2 in the grout. The reaction order on TiO2 with respect to NO concentration is determined to be positive. Evidence was collected for photo-assisted NO adsorption on the surface of the sample. Cement-bound photo-catalysts are especially attractive for large-scale applications, because cement is a relatively low cost binder. TiO2 is widely used for the application to the improvement of the living environment due to anti-stain, self-cleaning, and super hydrophilic properties. It can be used simultaneously as a structural component and photocatalytically active material. NO oxidation is a diagnostic tool for photocatalytic activity. Standard methods are necessary to analyze the activity of photocatalytic materials on NOx oxidation. But, the only standard method validated to analyze photocatalytic activity is ISO-22197:2007(E) standard. In the experimental part, the effects of relative humidity, catalyst loading, inlet concentration of pollutant and total flow rate of inlet gas on NO oxidation rates were analyzed. In addition, photocatalytic the activity of some industrial samples for oxidation of NOX is investigated. The activity of the sample is improved with increasing TiO2 amounts. Photo-assisted adsorption of the NO on the surface of the sample was also observed. Experiments performed in dark indicated that UV irradiation created active sites over TiO2 for adsorption of NO. Water adsorption calorimetry studies indicated that TiO2 surfaces can easily adsorb water, with a heat of adsorption of 80 kJ/mol in the first monolayer. On the contrary oxygen adsorption is not as facile as water adsorption.

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Citation Formats
İ. Bayar, “Photocatalytic oxidation of NOX over TiO₂ containing cement based materials,” M.S. - Master of Science, Middle East Technical University, 2013.