Photocatalytic degradation of biological contaminant (E. coli) in drinking water under direct natural sunlight irradiation using incorporation of green synthesized TiO2, Fe2O3 nanoparticles

Abstract

AbstractGlobally, there is a severe problem of widespread water contamination. Adsorption and photocatalytic degradation are considered the most suitable methods for removing these water pollutants because of their simplicity, environmental friendliness, and capacity to generate high-quality water. By a completely green route, in this recent study, the fungus Aspergillus tubingensis was able to synthesize TiO2 and Fe2O3 NPs with an average diameter of 28.0 and 65 nm, respectively. The smallest NPs diameters were produced when the precursor salt concentrations were 10−3 M and 10−2 M for TiO2 and Fe2O3, respectively, at pH 3 and an incubation time of 72 h. The biosynthesized NPs were characterized using DLS, TEM, EDX, and VSM. They were then applied in the preparation of titanium-iron nanocomposites with different ratios (1:1, 1:2, and 2:1 (w/w)) and characterized by FTIR and XRD. In this study, Escherichia coli (E. coli) was photo-catalytically inactivated using a TiO2–Fe2O3 nanocomposite as a photocatalyst in the presence of direct sunlight. This material’s photocatalytic performance was evaluated in comparison to that of TiO2 and Fe2O3 NPs. After 60 min of exposure to direct sunlight, the cell death was estimated as 97.97%, 99.32%, 89.06%, 30.96%, and 25.14% in the presence of TF-1, TF-2, TF-3, TiO2, and Fe2O3, respectively. Under direct natural sunlight irradiation for 60 min, TiO2 and Fe2O3 nanoparticles alone have the least impact on E. coli, whereas TF-2 nanocomposite has a higher level of photocatalytic bacterial inactivation competency than TF-1 and TF-3 nanocomposites. No significant toxicity has been observed for TF-2-treated water samples in the toxicity assessment.