Efeito da moagem do TiO2 e da razão Si/Al da zeólita na foto-oxidação de corante têxtil catalisada por TiO2 suportado em zeólita ZSM-5

Abstract

The heterogeneous photocatalysis is a powerful oxidative technique with positive developments in degradation of pollutants by transient radical oxidant, which are generated by reactions of redox from water and O2 molecules adsorbed on the catalysts surface, when they absorb sufficient energy for activation. The synthesis and select appropriate catalysts is an essential step for photocatalysis studies to absorb radiation in the visible region to photo-excitation with sunlight, with capacity to promote pollutant or water molecules adsorption. Samples of Kronos titania (anatase 100%) were treated in the mill Pulverisette type Fritsh to reduce the crystallite size for subsequent deposition on zeolite ZSM-5 surface with different Si / Al ratios. After the grinding treatment was found that there was a change of phase from anatase to rutile, accompanied by a reduction of the particle size and presence of contaminant pseudobrookite and hematite, from the vessel and the grinding balls. The photocatalytic tests resulted in better activity for the catalysts with higher percentage of anatase and lower concentrations of iron oxides. For different Si/Al of ZSM-5 was found that more aluminum atoms in the zeolitic network, the higher the proton and higher acidity ability to adsorb water molecules, promoting a greater amount redox reactions on the catalyst surface, increasing the activity photocatalytic.