N‐doped TiO₂ photocatalysts for bacterial inactivation in water

Abstract

BACKGROUND The elimination of diverse and pathogenic microbial loads in water imposes the exploration of effective disinfection techniques. The current study focused on the synthesis of N‐TiO2 photocatalysts and the investigation of their disinfection potential, in terms of Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus inactivation in aqueous samples under artificial sunlight. RESULTS N‐TiO2 photocatalysts were synthesized using various nitrogen precursors [urea, triethylamine‐(TEA) and NH3], exhibiting narrow band gaps and improved visible light response. The relative bactericidal activity of the catalysts followed the order N‐TiO2 (UREA) > N‐TiO2 (NH3)∼N‐TiO2 (TEA) > synthesized TiO2 > TiO2‐P25. The Gram‐negative indicators E. coli and P. aeruginosa, were readily inactivated, reaching reduction rates up to 6 log10 within 60 min of treatment at an initial bacterial concentration of 106 CFU mL−1 and a catalyst concentration of 50 mg L−1. The activity discrepancies among the catalysts were more pronounced in the case of B. cereus, which showed higher resistance, thus exhibiting slower inactivation rates. Complete elimination was achieved only with N‐TiO2 (TEA) within 60 min of irradiation at a loading of 100 mg L−1. Increasing the TEA concentration for the preparation of this catalyst from 25 to 89 v/v% did not enhance significantly the process. Operating conditions, including catalyst concentration, nitrogen precursor and, especially, bacterial species defined the disinfection efficiency up to a certain extent. CONCLUSION Solar photocatalysis with N‐TiO2 catalysts may be an effective disinfection technology if the operational conditions are established in relation to the microbial content in water, which includes opportunistic pathogens such as P. aeruginosa and B. cereus. © 2018 Society of Chemical Industry

Heterostructured Ag/g‐C3N4/TiO2 with enhanced visible light photocatalytic performances

“…Therefore, various effective strategies have been developed to improve the photocatalytic activity of TiO 2 and extend its photoresponse range from UV to the visible light. Examples include the use of noble metal deposition, surface sensitization, coupling of composite semiconductors, and doping with metal and non‐metal …”

“…Examples include the use of noble metal deposition, surface sensitization, coupling of composite semiconductors, and doping with metal and non-metal. [14][15][16][17][18][19][20][21] In recent years, a novel type metal-free visible light responsive semiconductor based on graphite carbon nitride (g-C 3 N 4 ) has attracted appreciable attention due to its promising optical properties, electronic structure, and photocatalytic activity. 22 (Tian) a band gap of 2.7 eV, g-C 3 N 4 exhibits considerable response in the visible-light region.…”

Delocalization of π‐Electron in Graphitic Carbon Nitride to Promote its Photocatalytic Activity for Hydrogen Evolution

“…In order to cope with the increasingly serious energy crisis, semiconductor photocatalysis has been considered as a prospective technique in response to the photocatalytic water splitting, [1][2][3][4] carbon dioxide reduction, [5][6][7] air pollutant removal, [8] degradation of organic compounds [9][10][11] and bacteria disinfection. [12,13] To date, graphitic carbon nitride (g-C 3 N 4 ), as a promising photocatalyst, has drawn considerable attention in these applications due to its appropriate band gap (2.7 eV), favorable chemical stability, zero toxicity and low cost. g-C 3 N 4 has taken up the most prominent position in the hydrogen evolution reaction (HER) in which clean solar energy is converted to hydrogen energy.…”

Facile synthesis of C, N-TiO2 nanorods via layered Ti 3 O 7 2 − -TMAH interlaminar bonding interaction and their enhanced catalytic performance

“…In this respect, some non-metallic organic compounds (e.g. urea [18][19][20] and polyaniline [21]), noble metals [22,23] and semiconductor composite [24] can be used to modify the surface of TiO 2 nanoparticles to enhance their photocatalytic activities, thereby effectively inhibiting the recombination of photoinduced carriers and broadening the absorption wavelength. Bonding interaction is an effective strategy for modifying catalyst materials.…”