Inactivation of Staphylococcus aureus in water by means of solar photocatalysis using metal doped TiO2 semiconductors

BACKGROUND: The need for clean water and high hygiene standards has led to the exploration of effective disinfection techniques for the elimination of persistent and pathogenic microorganisms. The disinfection potential of cation-doped titania was investigated in terms of Staphylococcus aureus elimination in aqueous samples under artificial and natural sunlight. RESULTS: Fe-, Al- and Cr-doped TiO2 were prepared with dopant loadings of 0.04, 0.3 and 2 wt%. Cation doping resulted in absorption shifts into the visible region, thus rendering the use of solar light feasible. The relative activity for S. aureus inactivation decreased in the order Fe-TiO2 > Al-TiO2 > Cr-TiO2 > P25. For example, an approximately 5 log reduction was obtained in 30, 10 and 6 min when Fe-loading was 0.04, 0.3 and 2 wt%, respectively, at an initial bacterial concentration of 107 CFU mL(-1) and a catalyst concentration of 50 mg L-1. The catalyst concentration in each case affected the overall process up to a certain extent. Scanning electron microscopy revealed interaction between the catalyst nanoparticles and bacterial cells during treatment, with significant alteration in their shape, morphology and size. Under natural sunlight conditions Fe-TiO2 and Al-TiO2 could achieve a 99.9% killing of S. aureus population after 60 min. CONCLUSION: In a nutshell, solar photocatlysis with cation-doped titania is an effective disinfection technology for adaptable and tolerant pathogens such as S. aureus. (C) 2016 Society of Chemical Industry