Antibacterial effect of new photocatalytically active "complex oxides/PMMA" composites under visible-light irradiation

New photocatalytic materials based on complex oxides and a widely used and cheap polymer (PMMA) have been prepared. Among complex oxides previously investigated, the following have been used-RbTe_1.5W_0.5O₆, CsTeMoO₆, CsV_0.625Te_1.375O₆, NaVMoO₆, KVMoO₆. For comparison, the binary oxides TiO₂ and WO₃ were used. The form of PMMA matrix was used as sponge and glass. The amount of powder in PMMA was selected based on retaining the polymer properties and getting the photocatalytic activity, which corresponds to 1% powder in sponge and 0.5% in glass. The "photocatalyst/PMMA" composites decompose the methylene blue under visible and UV light as well as possess antibacterial properties. The high electron-hole recombination was found out for composites photocatalysts, which significantly influences only on organic compounds decomposition in solutions. However, there is no direct dependence between effective photodegradation of simple organic molecules and antimicrobial properties. Inactivation of bacteria is determined by many factors such as active generated radicals, adsorption properties of the surface and the photocatalyst form, which can change the main active radicals. The comparison of photocatalytic action on organic solutions and bacteria of initial powders and PMMA composites allow choosing the most effective combination for further application. The most promising antimicrobial properties for composites have been obtained using compounds with β-pyrochlore structure.