Optimization of carbamazepine photodegradation on defective TiO2-based magnetic photocatalyst

In this work, carbamazepine (CBZ) degradation over defective Fe3O4@SiO2/d-TiO2/Pt photocatalyst was studied. Within the titania structure, Ti vacancies and Pt nanoparticles were introduced to enhance the photocatalyst's light absorption and influence charge carriers' mobility. For the carbamazepine degradation, process parameters, e.g., temperature, flux intensity, photocatalyst loading, aeration, pH, and addition of H2O2, were optimized for 4 or 5 different levels, with the quadratic model including 2-factor interactions determined to analyze the effect of these parameters. Carbamazepine presence and by-product formation were monitored using the HPLC-DAD system together with additional HPLC-TOFMS analysis for further identification of created compounds. Acridine was selected as an additional factor, indicating differences in the performed process of photolysis and photocatalytic CBZ degradation. Pure TiO2 exhibited the highest efficiency of CBZ degradation under alkaline conditions, while the performed optimization shows that a combination of H+ and H2O2 addition is crucial to achieve high CBZ removal and its mineralization in the presence of Fe3O4@SiO2/d-TiO2/Pt photocatalyst. The obtained results were discussed concerning photocatalyst structure, generation of reactive oxygen species inside H+/H2O2/photocatalyst system, and the possible effect of introduced Ti vacancies. In terms of reusability, the performance of Fe3O4@SiO2/d-TiO2/Pt photocatalyst was stable after 8 subsequent cycles of carbamazepine degradation.