This work describes the sol-gel mixed oxide SiO2/TiO2 property, ST, as prepared, and submitted to heat treatment a 773 K, STC. SEM and EDS images show, within magnification used, a uniform distribution of the TiO2 particles in SiO2/TiO2 matrix. Both, ST and STC adsorb hydrogen peroxide on the surface and through EPR and UV-Vis diffuse reflectance spectra, it was possible to conclude that the species on the surface is the peroxide molecule attached to the Lewis acid site of titanium particle surface, alphaTi(H2O2)+. As the material is very porous, presumably the hydrogen peroxide molecule is confined in the matrix pores on the surface, a reason why the adsorbed species presents an exceptional long lived stability.

O óxido misto poroso SiO2/TiO2/Sb2O5, obtido pelo método de processamento sol-gel, apresentou uma boa propriedade e elevada capacidade de troca iônica com os íons Li+, Na+ e K+. No processo de troca iônica H+/M+, o H+/Na+ apresentou um caráter ideal. Os equilíbrios de troca de Li+ e K+ foram quantitativamente descritos através de um modelo de centros tetradentados fixos. Os resultados de simulação evidenciaram que para troca H+/Li+ temos uma situação normal: a afinidade do material pelo íon Li+ decresce com o aumento do grau de troca. Para o K+, o efeito positivo do cooperativismo que facilitaria a troca H+/K+, revelou um efeito contrário.

The porous mixed oxide SiO2/TiO2/Sb2O5 obtained by the sol-gel processing method presented a good ion exchange property and a high exchange capacity towards the Li+, Na+ and K+ ions. In the H+/M+ ion exchange process, the H+ / Na+ could be described as presenting an ideal character. The ion exchange equilibria of Li+ and K+ were quantitatively described with the help of the model of fixed tetradentate centers. The results of simulation evidence that for the H+ / Li+ exchange the usual situation takes place: the affinity of the material to the Li+ ions is decreased with increasing the degree of ion exchange. On the contrary, for K+ the effects of positive cooperativity, that facilitate the H+ / K+ exchange, were revealed.