Combined photocatalytic degradation of pollutants and inactivation of waterborne pathogens using solar light active α/β-Bi2O3

A solar light active composite of α/β-Bi2O3 was synthesized using a chemical-free solid-state reduction method. The obtained composite was characterized by X-ray diffraction, UV–vis spectroscopy, field emission scanning electron microscopy, and zeta potential. Initially, to validate the photocatalytic effectiveness, the obtained α/β-Bi2O3 composite was used to degrade indigo carmine dye. Then, the inactivation of E. coli and S. aureus waterborne pathogens was performed on solid and in liquid media. On solid agar media, a significant inhibition zone was observed for both bacterial strains. Similarly, in liquid culture, these strains E. coli and S. aureus were reduced from 1 × 106 CFU/mL to a few CFU/mL, after 240 min of photocatalytic exposure. Furthermore, mixed wastewater of indigo carmine and E. coli/S. aureus were tested to study the combined photocatalytic mechanism against the organic dye and microorganisms. Overall, the obtained results suggested the efficacy of α/β-Bi2O3 towards visible light inactivation of bacteria even in combination with other pollutants, highlighting the great potential of the advanced photocatalytic process for combined treatment of organic pollutants and pathogens.