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.