Hydroxyl radicals are very reactive and unselective, they can decompose very stable organic molecules. Advanced oxidation processes based on this decomposition are used to purify wastewater. Photocatalysis with TiO2 is one of these processes.
By irradiating TiO2 in water with UV light, hydroxyl radicals can be generated. The efficiency of photocatalysis depends on the conditions in the solution and the properties of the photocatalyst. The properties can be optimized by changing the synthesis conditions.
In the experimental work, the influence of the synthesis parameters on the properties of the nanostructured TiO2 photocatalyst was determined. Various synthesis parameters were changed, including the added amount of H2O2 and NaOH, the duration and temperature of hydrothermal synthesis, and the duration and temperature of thermal treatment. The photocatalytic activity of the samples was determined by UV-Vis spectroscopy, the specific surface area was determined by BET adsorption isotherm, the structure was determined by X-ray diffraction and the morphology of the formed particles was observed by scanning electron microscope.
The experiments showed that nanostructured flower-like microparticles are formed during the synthesis. Their shape is already determined by hydrothermal synthesis, the conditions of thermal treatment affect their crystallinity and photocatalytic activity. At higher temperatures, the particles have a higher degree of crystallinity and the dye in the solution is degraded more rapidly. The temperature of thermal treatment has the greatest influence on the photocatalytic activity, while other parameters have little or no influence. The results of BET adsorption isotherms show that the specific surface area of the particles is also most affected by the temperature of thermal treatment, which is also confirmed by scanning electron microscope.
The results show that the repeated use of a photocatalyst does not reduce its activity.
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