Photocatalytic performance of TiO<inf>2</inf>/zeolites under simulated solar light for removal of atenolol from aqueous solution

Abstract

Removal of the β-blocker atenolol from an aqueous solution was studied using TiO2/zeolites, prepared by a simple and cost-effective solid-state dispersion method. Synthetic zeolites 13X and ZSM-5 (Si/Al = 40) and natural zeolite clinoptilolite were used as one component of the hybrid materials, whereas TiO2 nanocrystals obtained from TiO2 nanotubes and P25 TiO2 nanoparticles were used as the other. The synthesized materials were characterized by X-ray powder diffraction, transmission electron microscopy, Fourier transformed infrared spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy and scanning electron microscopy with energy-dispersive spectroscopy. The photocatalytic activity for the degradation of atenolol was investigated under simulated solar light. Additionally, the effect of initial pH on atenolol removal and the reusability of prepared catalysts were tested. The best loading of TiO2 was 20 wt% over all investigated zeolites. The degradation of atenolol followed the pseudo-first-order kinetics. The photocatalytic degradation of atenolol after 70 min of irradiation was ~ 50% for TiO2/13X materials, ~ 45% for clinoptilolite combined with P25 TiO2 and ~ 57% for clinoptilolite combined with TiO2 nanocrystals obtained from TiO2 nanotubes. The results showed the highest removal efficiency after 70 min of irradiation for ZSM-5 combined with P25 TiO2 (~ 94%), followed by ZSM-5 combined with TiO2 nanocrystals obtained from TiO2 nanotubes (~ 88%) at near-neutral pH (~ 6.5). The total removal of atenolol from an aqueous solution for TiO2/ZSM-5 materials resulted from two processes: adsorption and photocatalytic degradation. The TiO2/ZSM-5 photocatalysts can be easily recovered and reused as their activity was preserved after four cycles.