Effect of dispersity and porous structure of TiO2 nanopowders on photocatalytic destruction of azodyes in aqueous solutions

Photocatalytic activity of TiO2 nanopowders of anatase modification with various particle sizes and specific surface areas has been studied in the process of photocatalytic decolorization of aqueous solutions of methylene bluе and direct blue 2С azodyes. Through scanning electron microscopy and low-temperature N2 adsorption method, it was found that TiO2 nanopowders have a particle size of 5-120 nm with a specific surface area of 15-120 m2⋅g-1. The used TiO2 samples are characterized by mesoporous structures with an average pore size of 4.3-14.9 nm. The photocatalytic activity of TiO2 was evaluated via the decolorization of azodyes solutions. It was shown that the efficiency of decolorization symbatically changes with the dye adsorption value on the TiO2 surface and the degree of decolorization rises when the surface area of TiO2 nanopowders increases. It was found that TiO2 photocatalytic activity essentially depends on adsorption interactions between the dye molecules and catalytic active centers on the TiO2 surface, and these interactions, in turn, are greatly affected by pH of the solution. Keywords: TiO2, surface area, photocatalytic decolorization, azodye, adsorption.