Hydroxyl Radical Generation by Recyclable Photocatalytic Fe3O4/ZnO Nanoparticles for Water Disinfection

Abstract

Advanced oxidation processes based on photocatalytic generation of •OH radicals have emerged as promising technologies for the removal of recalcitrant pollutants in water. However, their poor recyclability has reduced their potential large-scale application. Herein, a Fe3O4-embedded ZnO system has been prepared and its photocatalytic •OH radicals activity was evaluated by monitoring the photo-assisted bleaching of p-nitrosodimethylaniline (pNDA). Water disinfection performance was determined by measuring Escherichia coli inactivation under different conditions. Bleaching of nearly 80% of the initial pNDA concentration after just 120 minutes under UV365nm irradiation was determined. Bacterial inactivation at different concentrations (0.1, 1.0, and 5.0 mg mL−1) of the Fe3O4/ZnO nanocomposite was determined, finding that the best performance was obtained at 0.1 mg mL−1 (90%) just after the first 30 minutes under UV irradiation. The materials are easily magnetically recovered and their performance evaluated after 3 consecutive cycles of reuse. These magnetic and photoactive nanocomposites showed improved performance and could be used for wastewater treatment or disinfection processes of water.