MoOx/TiO2 immobilized on quartz support as structured catalyst for the photocatalytic oxidation of As(III) to As(V) in aqueous solutions

In the present paper, a stable MoOx/TiO2photocatalyst, active in the photocatalytic oxi-dation of As(III) to As(V), was successfully immobilized on quartz flakes and tested underdifferent UV irradiation intensities and initial As(III) concentration. The structured photo-catalyst was prepared in two steps, realizing a coating of TiO2on quartz flakes by sol–gelmethod, and then transferring the molybdenum species through an equilibrium adsorptionmethod. The obtained samples were characterized by SEM–EDAX analysis, N2adsorptionat −196◦C and Laser Raman spectra. SEM–EDAX results showed the preferential interactionbetween Mo species and titania layer and a very good dispersion of MoOxon the TiO2filmdeposited on the transparent support. Raman spectra confirmed the presence of hydratedoctahedrally polymolybdate species well anchored to the TiO2surface. Photocatalytic oxi-dation tests showed that the complete conversion of As(III) to As(V) was achieved in thepresence of MoOx/TiO2catalyst supported on quartz flakes within 120 min of UV irradiation.The catalyst maintained an excellent photocatalytic activity and durability after four cyclesin aerated water avoiding the photoreduction of the MoOxspecies. The developed structuredphotocatalyst can be easily separated from the reaction mixture, making it a very promisingcatalyst to be employed in continuous reactors for the photocatalytic treatment of arsenicpolluted water.