Solar-activated iron oxide-doped titanium dioxide for bacterial inactivation in water

Abstract

Access to clean and safe drinking water is a global concern especially for people living in remote, scattered and impoverished areas who lack access to centralized water treatment facilities. To address this, the current study developed and evaluated a solar photocatalytic disinfection system using titanium dioxide (TiO 2 ) doped with ferric oxide (Fe 2 O 3 ). The TiO 2 /Fe 2 O 3 photocatalyst was synthesized using titanium oxide and iron (III) nitrate nonahydrate. The photocatalyst was characterized by Fourier Transform Infrared Spectroscopy (FTIR) to identify its chemical composition and Scanning Electron Microscopy (SEM) to determine the surface morphology, and X-ray Diffraction (XRD) analysis is used to determine crystal structure. The disinfection capability was evaluated using synthetic water containing Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under natural sunlight. The effect of photocatalyst load, and bacterial type was studied. The reaction kinetics and photocatalyst recovery, regeneration and reuse were evaluated. Photocatalyst load of 0.5 g/L achieved 100% and 99.61% inactivation of E. coli and S. aureus, respectively within 2 h. The disinfection data obeyed pseudo-first-order kinetics with rate constants of 0.0263 min −1 and 0.0244 min −1 for E. coli and S. aureus , respectively. Reusability tests indicated excellent photocatalyst stability, the disinfection efficiency was 89.06% and 87.93% for E. coli and S. aureus after four cycles, respectively indicating the robustness of the photocatalysts. The high effectiveness against Gram-positive and Gram-negative bacteria, multiple use and utilization of sunlight make the system appropriate for decentralized water treatment.