Diclofenac Degradation in Aqueous Solutions Using Advanced Oxidative Processes

The photocatalytic activity of iron-containing metal–ceramic composites based on silicon nitride modified with semiconductor tantalum oxo compounds in oxidative degradation of diclofenac (DCF) was studied. The composites were synthesized by autowave combustion of ferrosilicoaluminum with different additions (5, 10, 15 wt %) of tantalum metal in a nitrogen atmosphere. The phase composition was determined by X-ray diffraction and IR spectroscopy, and the content of elements in local surface areas was quantitatively evaluated by electron microprobe analysis. The activity of composites under the conditions of heterogeneous photocatalysis, heterogeneous photocatalysis combined with photo-Fenton and Peroxone processes under UV irradiation, and catalytic ozonation under UV and visible light irradiation was studied. The combination of heterogeneous photocatalysis and Peroxone process is the most effective. The Lаngmuir–Hinshelwood scheme was applied to elucidate the mechanism of DCF photocatalytic degradation.