Comparative Efficiencies of TiO2 Photocatalysts on β-Blocker Metoprolol Degradation by Solar Heterogeneous Photocatalysis

The degradation of metoprolol (MET) has become a topic of interest due to its persistence in the environment. TiO₂ is a catalyst commonly used for the degradation of emergent pollutants through photocatalysis due to its physicochemical properties, and it has been pointed out that its crystallite structure and size affect the photocatalytic efficiency. In this study, three brands of TiO₂ (Evonik P25, Fermont and Sigma Aldrich) were characterized to evaluate their crystallographic and morphological properties. Then, their photocatalytic capacity was tested in solar heterogeneous photocatalysis experiments when degrading MET under various experimental conditions. The TiO₂ catalysts tested yielded different results when degrading MET in photocatalytic experiments, indicating that presence of a rutile phase in the catalyst and the crystal size are important factors for the success of this semiconductor. Results from solar heterogeneous photocatalysis for MET degradation indicate efficiencies as P25 > Sigma-Aldrich > Fermont, but demonstrate that, even lower-priced TiO₂ catalysts yield good results for contaminant degradation (90% MET degradation for P25 against 63% when using Sigma Aldrich TiO₂). This study highlights the potential of solar photocatalysis with lower-priced TiO₂ catalysts as a viable and sustainable solution for the decontamination of pharmaceutical wastewater in large scale photocatalytic applications.