Mechanochemical Synthesis of Anatase-Rutile Phases at Ball Milling in Different Conditions and Its Cause and Effect on a Photo-Oxidation Process / Síntese Mecano-Química De Fases Anatômicas Na Moagem De Bolas Em Diferentes Condições E Sua Causa E Efeito Em Um Processo De Foto-Oxidação

Abstract

This study aims to evaluate the effect of the grinding parameters applied to TiO2 comminution, which forms a heterojunction of anatase-rutile phases and reduces markedly the size particle. This material is a well-knowm photocatalyst in environmental issues such as degradation of synthetic dyes, mainly due to the large surface area and oxidative radicals generations ability. The influence of time, rotational speed and the solvent was investigated in the grinding process. Catalysts were prepared by a deposition method and were characterized by XRD, textural analysis (BET area), potential electrophoretic, photoacoustic and Mössbauer spectroscopy. The comminution procedure reduced the size of TiO2 crystallites from 87 nm to 22 nm as well as the surface area and pore diameter. The best photocatalytic activity was for TiO2 comminuted for 10 min and 300 rpm in a dry medium supported on ZSM-5. It was registered that the photoactivity of TiO2 decreased with the transition of anatase to rutile phase and also by the iron oxides insertion during the comminution process. This study has a great technologic contribution because it elucidates primary issues on the particle sizes reduction in the catalysts production, whose function is to have a better metal distribution on the support's surface.