Niobium oxide dispersed over PET waste activated carbon: an efficient catalyst for oxidation of the fungicide prothioconazole

Abstract

Composite materials based on Nb2O5 nanoparticles dispersed over activated carbon (Nb/AC) obtained from PET waste were used as catalysts for wastewater treatment. These composites were synthesized by mechanical mixing of AC and commercial Nb2O5, followed by H2O2 treatment. The methylene blue dye (MB) was used as a model contaminant and the fungicide prothioconazole (PCZ) was the target molecule. Contaminant removal from water occurred mainly via adsorption by AC and via a combined process of adsorption/oxidation in the case of Nb/AC composites. The increase in the Nb amount in the catalysts reduced the BET surface area but increased the reaction rates due to the oxidation properties of Nb2O5. The reaction mechanism is Mars–Van Krevelen-like, driven by the peroxo groups (active sites) on the Nb2O5 surface. Moreover, the Nb/AC composites were highly efficient catalysts for PCZ oxidation and its main metabolite (prothioconazole-desthio) from water.