Disinfection and Mechanistic Insights of Escherichia coli in Water by Bismuth Oxyhalide Photocatalysis

Abstract

This study demonstrates the potential of a new BiOCl Br photocatalyst to disinfect Escherichia coli in water under simulated solar irradiation. Photocatalytic efficiency was examined for different photocatalyst loadings, solar wavelengths, exposure times, photocatalyst concentration × contact time (Ct) concept and with the use of scavengers. To elucidate the inactivation mechanism, we examined DNA damage, membrane damage, lipid peroxidation and protein release. Both photolysis and photocatalysis were negligible under visible irradiation, but enhanced photocatalytic activity was observed under solar UVA (λ > 320 nm) and UVB (λ > 280 nm), with 1.5 and 3.6 log inactivation, respectively, after 40 min of irradiation. The log inactivation vs Ct curve for E. coli by UVA/BiOCl Br was fairly linear, with Ct = 10 g L × min, resulting in 2 log inactivation. Photocatalytic treatment led to membrane damage, but without lipid peroxidation. Accordingly, protein was released from the cells after UVA or UVA/BiOCl Br treatment. Photocatalysis also increased endonuclease-sensitive sites vs photolysis alone, by an unknown mechanism. Finally, E. coli inactivation was not influenced by the addition of tert-butanol or l-histidine, implying that neither hydroxyl radicals nor singlet oxygen reactive species are involved in the inactivation process.

Insights into the Photocatalytic Bacterial Inactivation by Flower-Like Bi2WO6 under Solar or Visible Light, Through in Situ Monitoring and Determination of Reactive Oxygen Species (ROS)

“…Considering the redox potential of O 2 /H 2 O 2 = +0.682 eV vs NHE [51], H 2 O 2 seems to be generated initially (Equation (8)) which is followed by the formation of different species according to the relations 9-10 in the photocatalytic reaction. It is worth noting that the powerful hole can directly attack bacteria cells in the photocatalytic oxidation process, which was also confirmed by the hole scavenger [45,52].…”

“…The interface potential is shown to drastically drop within 8000 s (2.2 h) when the bacterial reduction is reduced by 99.90%, which is equivalent to 3 logs as shown in Figure 5. The interface potential recovers to its initial value as shown in Figure 10 after the inactivation of bacteria [52]. The recovery to the initial pH-level occurs when the intermediate acids are mineralized to CO 2 by the photo-Kolbe reaction according to Equation (12) [53,54].…”

Solar Photocatalytic Degradation of Trace Organic Pollutants in Water by Bi(0)-Doped Bismuth Oxyhalide Thin Films

“…13 In another study, the high oxidation potential of the BiOX hole h vb + resulted in direct bacterial oxidation of Escherichia coli by its adsorption onto the catalyst surface. 14…”

“…It has established the high degradation rate of rhodamine B using BiOX (BiOCl 0.875 Br 0.125 ) under visible light . In another study, the high oxidation potential of the BiOX hole h vb + resulted in direct bacterial oxidation of Escherichia coli by its adsorption onto the catalyst surface …”

High‐performance photocatalysts for the selective oxidation of alcohols to carbonyl compounds

“…Bismuth oxyhalides (BiOX) and their heterojunctions are posed as an attractive semiconductor for photocatalytic applications such as water splitting, [89][90][91][92] pollutant mineralization, [93][94][95][96][97] and microbial disinfection. [93,98] Apart from their commendable optical properties and bandgap energies, the layered morphology of BiOX prevents the recombination of charge carriers via an internal electric field between ([BiO] 2 ) 2+ layers and the negatively charged halogen atoms. [99] Based on this idea, Xie et al [28] reported the synthesis of BiOX (X = Cl, Br, and I) by a facile hydrothermal method, which was then used for the selective conversion of aliphatic alcohols (pentan-1-ol, hexan-1-ol and heptan-1-ol) under visible light.…”