Advanced oxidation processes based on photocatalytic generation of hydroxyl radicals (OH●) have emerged as promising technologies for the removal of recalcitrant pollutants in water. However, their poor recyclability has reduced their potential large scale application. In this study, the magnetic and photocatalytic nanocomposites have been prepared by the coupling of ZnO with Fe3O4 and ZnFe2O4 via simple synthetic approaches. Characterization of the nanocomposites and their lone components was performed using DLS, FTIR, PL, XRD, SEM-EDS and BET isotherms. The photocatalytic activity was evaluated by monitoring the photo-assisted bleaching of the OH● radical scavenger p-nitroso dimethylaniline (pNDA) using UV365nm irradiation. Using ZnFe2O4/ZnO with a 1:8 ratio (0.1 mg mL-1) had an efficiency of &gt;80% after 120 min, which is comparable to pure ZnO. Water disinfection performance was determined by assessing E. coli inactivation. Bacterial inactivation was achieved, with the best performances obtained by Fe3O4/ZnO at 0.1 mg mL-1 with an efficiency of 90% just after the first 30 min under UV365nm irradiation; and remarkably, ZnFe2O4/ZnO at 1:8 (0.1 mg mL-1) proved to be more effective for bacterial inactivation than ZnO alone, with an inactivation performance of 90% after 15 min. While the photoactive nanocomposites showed good performance and could be used for wastewater treatment or disinfection processes, differences where noted among the different magnetic cores. Fe3O4 provided a better recovery of the nanocomposites, which translates on better recyclability, while ZnFe2O4 had better photocatalytic efficiency. These results should be evaluated in terms of the specific application, whether either recyclability or efficiency is needed, and more importantly, these magnetically separable materials could benefit treatment processes by recycling the photocatalyst, without any loss in consecutive uses.

Development of magnetic ZnO nanoparticles for wastewater disinfection

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.