Authors: M. Kralova, V. Kasparek, J. Cihlar, I. Levchuk, and M. Sillanpaa
Heterogeneous photocatalysis is a very effective method for decomposition of a whole range of water pollutants. Lanthanides-doped titanium dioxide was chosen as a suitable photocatalytic material and the influence of synthesis conditions on physical properties, as well as on photocatalytic activity, was evaluated. Titanium dioxide was prepared via a sol-gel synthesis followed by a solid state reaction under different conditions such as various temperature (450°C, 550°C, 650°C) and reaction time (4 hours, 8 hours, 12 hours). The crystalline phase was investigated using X-ray diffraction (XRD) and the results were confirmed by Raman spectroscopy. Structure, as well as particle size, were examined using scanning electron microscopy (SEM). Specific surface area was calculated from Brunauer-Emmett-Teller analysis (BET). Band gap energy was examined using ultraviolet-visible spectroscopy (UV-vis) from diffused reflectance measurement. Photocatalytic activity was studied as a degradation rate of the commonly used herbicide metazachlor. The decomposition was carried under UV light and the decreasing metazachlor concentration was measured using high performance liquid chromatography (HPLC). Temperature of 550 °C and duration of the synthesis for 8 hours were determined to be the best conditions for the solid state reaction.
Keywords: doped titania, metazachlor, photocatalysis