HYDROTHERMAL SYNTHESIZED TiO2 BASED NANOPOWDERS FOR PHOTOCATALYTIC APPLICATIONS

Hydrothermal synthesis was used to obtain nanostructured TiO2 based nanopowders. There were prepared pure and ZrO2 doped compositions consisting mainly of anatase phase with crystallite size up to 20 nm. The agglomerates of the as-synthesized materials had dimensions ranging from a few hundreds nanometers to 200 microns. The investigations concerning the thermal behavior revealed the presence of an exothermal effect at around 550 degrees C which could indicate a possible phase transformation of anatase to rutile but further studies are required. The photocatalytic properties of the TiO2 hydrothermal nanostructured powders were evaluated in a photoreactor under UV (lambda(max) = 365 nm) irradiation using methylene blue dye and the effect of H2O2 on the photocatalytic efficiency was tested. The results may be attributed to the presence of free radicals and holes generated in the anatase nanostructure evidenced by EPR spectra of nanopowders.