Abstract

Carbon-supported PO43-/Fe3+-based nanocomposites were prepared by a thermal hydrolysis method. The influence of the molar ratio PO43-/Fe3+ upon the kinetics of adsorption and photocatalytic degradation of methylene blue was evaluated. In terms of the surface reaction rate, up to 8 times higher photoactivity (99 % dye conversion) than the commercial F400 activated carbon (39 % dye conversion) was found for the sample containing a ratio PO43-/Fe3+ ca. 0.5. This composite was selected for a carefully study of spin-trapping of (OH)-O-center dot and O-2(center dot-) adduct formation. O-2(center dot-). A preferential formation of O-2(center dot-) and a strong inhibiting effect was observed in the formation of these reactive oxygen species attributed to the phosphate-based groups. In addition, a composite was prepared using the best carbon-supported P-Fe-based photocatalysts and a commercial TiO2. An inhibiting effect of the photocatalytic activity of TiO2 was observed in presence of P-containing catalysts in agreement with the decrease in the spin-trapping signals. A mechanism for the trimer aggregation of methylene blue adsorption on carbon-supported P-Fe-based nanocomposite following degradation under UV-vis irradiation is proposed.