Phenol decomposition using Mn+/TiO2 photocatalysts supported by the sol-gel technique on glass fibres

The photoactivity of supported TiO2 and Mn+/TiO2 (Mn+ = Li+, Zn2+, Cd2+, Ce3+, Co3+, Cr3+, Fe3+, Al3+, Mn2+ and Pt-0) layers, fixed on glass fibres by the sol-gel technique, was tested using the reaction of phenol degradation. The concentration of metal dopant in the immobilized photocatalysts was 5 mol.% Mn+:Ti4+. In addition, the effect of platinum loading in Pt-0/TiO2 samples (Pt-0 content in the range 0.5-5.0 mol.% Pt-0:Ti4+) was investigated. The prepared materials were also characterized by their isoelectric points and reflectance spectra. The photoactivity of the materials prepared is strongly dependent on the character and concentration of the dopant. The best results in terms of phenol decomposition were obtained for dopant-free TiO2, Li+/TiO2, Zn2+/TiO2 and Pt-0/TiO2 (Pt content, less than 5 mol.% Pt-0:Ti4+). However, using Pt-0/TiO2 layers, we observed a slower decomposition of hydroquinone, which is produced as an intermediate by phenol hydroxylation. The presence of Co3+, Cr3+, Ce3+, Mn2+, Al3+ and Fe3+ ions in the TiO2 photocatalyst (5 mol.% Mn+:Ti4+) has a detrimental effect on its photoactivity. (C) 1997 Elsevier Science S.A.