TiO 2 -based photocatalytic disinfection of microbes in aqueous media: A review

Reddy, P. Venkata Laxma; Kavitha, B.; Kim, Ki‐Hyun

doi:10.1016/j.envres.2017.01.018

Cited by 351 publications

(99 citation statements)

References 48 publications

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“…The poor disinfection for photolysis experiments is ascribed to the protection of remaining active cells by the metabolites released from the destructed cells [83,85]. The disinfection mechanism of microbes in WW may be attributed to the oxidative degradation of cells by reactive oxygen species, increase of cell permeability, leakage of minerals, DNA/RNA damage, and inhibition of protein synthesis [83,86,87].…”

Section: Photocatalytic Wastewater Disinfectionmentioning

confidence: 99%

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

et al. 2020

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This work outlines an experimental and theoretical investigation of the effect of molybdenum (Mo) doping on the oxygen vacancy formation and photocatalytic activity of TiO 2 . Analytical techniques such as x-ray diffraction (XRD), Raman, x-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to probe the anatase to rutile transition (ART), surface features and optical characteristics of Mo doped TiO 2 (Mo-TiO 2 ). XRD results showed that the ART was effectively impeded by 2 mol% Mo doping up to 750°C, producing 67% anatase and 33% rutile. Moreover, the crystal growth of TiO 2 was affected by Mo doping via its interaction with oxygen vacancies and the Ti-O bond. The formation of Ti-O-Mo and Mo-Ti-O bonds were confirmed by XPS results. Phonon confinement, lattice strain and non-stoichiometric defects were validated through the Raman analysis. DFT results showed that, after substitutional doping of Mo at a Ti site in anatase, the Mo oxidation state is Mo 6+ and empty Mo-s states emerge at the titania conduction band minimum. The empty Mo-d states overlap the anatase conduction band in the DOS plot. A large energy cost, comparable to that computed for pristine anatase, is required to reduce Mo-TiO 2 through oxygen vacancy formation. Mo 5+ and Ti 3+ are present after the oxygen vacancy formation and occupied states due to these reduced cations emerge in the energy gap of the titania host. PL studies revealed that the electron-hole recombination process in Mo-TiO 2 was exceptionally lower than that of TiO 2 anatase and rutile. This was ascribed to introduction of 5s gap states below the CB of TiO 2 by the Mo dopant. Moreover, the photo-generated charge carriers could easily be trapped and localised on the TiO 2 surface by Mo 6+ and Mo 5+ ions to improve the photocatalytic activity. coatings [8,9]. The most commonly existing crystalline polymorphs of TiO 2 are anatase, rutile and brookite [10][11][12]. Anatase is accepted to be the more active phase of TiO 2 and is preferred by the ceramic industries to fabricate light active antimicrobial indoor building materials such as ceramics, glass, tiles and sanitary surfaces [13,14]. This requires thermal stability of the anatase phase under typical ceramic processing conditions. TiO 2 anatase is mainly fabricated at low calcination temperatures (∼500°C) to prevent the anatase to rutile phase transition (ART) [15][16][17], which produces the less photo-active rutile phase. The photo-activity of anatase arises from its appropriate band edge positions, electron affinity, ionisation potential, and the long lifetime of charge carriers [10,12,18]. Moreover, transient photo-conductance analysis has revealed that the electron-hole recombination phenomena in anatase (101) phase is much slower compared to rutile (110), which is credited in part to the indirect band gap of anatase [11,19].The unit cells of anatase and rutile phases are composed of TiO 6 octahedra with titanium atoms at the centre and oxygen atoms at the vertices [20]. Both anatase and rutile have a t...

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Section: Photocatalytic Wastewater Disinfectionmentioning

confidence: 99%

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

et al. 2020

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“…Actually, photocatalytic disinfection is normally a multi‐factor controlled issue that combines the effects of more than one kind of reactive species. What's more, in water disinfection, characteristics of the water matrix, such as ionic strength, oxygen, pH, natural organic matter and even pollutants, also govern the dynamics of photocatalysis by affecting RSs generation and contact between photocatalysts and cells . In this section, the generation and roles of RSs, and the impacts of water matrix on photocatalytic disinfection are discussed in detail.…”

Section: Mechanisms Of Photocatalytic Pathogen Inactivationmentioning

confidence: 99%

“…Although a variety of reviews in the field of photocatalytic pathogen inactivation have been published, and the significance of architecture design of photocatalysts has been increasingly recognized, a comprehensive summary that specializes in 2D‐based photocatalysts for water sterilization is still lacking. In this review, a detailed overview of 2D nanomaterials for photocatalytic pathogen inactivation is presented by categories.…”

Section: Introductionmentioning

confidence: 99%

Two‐dimensional nanomaterials for photocatalytic water disinfection: recent progress and future challenges

Liu

Zeng

et al. 2018

J of Chemical Tech & Biotech

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Photocatalysis has received ever‐growing attention as a promising alternative to traditional water treatment technologies for waterborne biohazard inactivation. Due to unique optical, electronic, physicochemical properties and feasibility of functional architecture assembly, two‐dimensional (2D) nanomaterials have become important in developing novel photocatalysts. This review summarizes the recent progress in configuring nanostructures with 2D materials as building blocks for photocatalytic water disinfection. In this review, five categories of 2D nanomaterials, that is, graphene, graphitic carbon nitride, 2D metal oxides and metallates, metal oxyhalides and transition metal dichalcogenides, for photocatalytic pathogen inactivation are introduced. First, the synthesis process, nanostructure engineering and disinfection performance of 2D‐based photocatalysts are reviewed in categories. In the following section, the bacteria destruction mechanism based on the generation and roles of reactive species (RSs) is presented. Moreover, the effects of the chemical characteristics of the water matrix on photocatalytic bactericidal performance are discussed. Finally, the challenges regarding the development and application of 2D‐based photocatalysts for highly efficient water sterilization are highlighted. © 2018 Society of Chemical Industry

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“…Its antibacterial activity has been reported to be induced by reactive oxygen species (ROS), generated on the TiO 2 surface by UV irradiation [3,4]. ROS, including hydroxyl radicals and superoxides, attack the bacterial cell membranes and destroy them, thereby deactivating the bacterial cell [5]. TiO 2 nanoparticle has also been reported to penetrate the cell membrane and generate ROS in the cytoplasm, hence resulting in cell death.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, a variety of modifications in the photocatalysts has been reported to enhance their efficiency against bacteria, considering some well-identified limitations of titania-based photocatalysts, such as higher recombination of electron and hole and limited solar light absorption [5]. Silver-modified TiO 2 has been reported to delay the recombination time and show high antimicrobial property [6,7].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Antibacterial Property of Facet-Engineered TiO2 Nanosheet in Presence and Absence of Ultraviolet Irradiation

et al. 2019

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Titania (TiO 2 ) has attracted much attention recently for reducing bacterial diseases by the generation of reactive oxygen species (ROS) under UV irradiation. However, demand for higher photocatalytic activity due to higher recombination of electron and hole remains. The aims of this study were to make titania with higher antibacterial property and show the mechanisms of the bactericidal effect. In this study, we hydrothermally synthesized TiO 2 nanosheets (NS) with highly-oriented structures. Samples were divided into five groups, depending on the fluorine/titanium ratio in the raw material, namely NS1.0, NS1.2, NS1.5, NS1.8, and NS2.0. Facet ratio and nanosheet size increased with an increase of fluorine/titanium ratio. The photocatalytic activity of TiO 2 nanosheet was assessed by the generation of ROS. Hydroxyl radicals and superoxides were generated efficiently by ultraviolet light irradiation on NS1.5 and NS1.0, respectively. Antibacterial activity against Streptococcus mutans was assessed in the presence and absence of UV irradiation; NS1.0 showed superior antibacterial properties compared to commercially available TiO 2 nanoparticles, under both conditions, due to the oxidation of intracellular components and cell membrane. These results together suggested TiO 2 nanosheet induced bacterial cell death by oxidation, and TiO 2 facet engineering resulted in enhancement of both photocatalytic and antibacterial activities of TiO 2 .

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TiO 2 -based photocatalytic disinfection of microbes in aqueous media: A review

Cited by 351 publications

References 48 publications

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Two‐dimensional nanomaterials for photocatalytic water disinfection: recent progress and future challenges

Enhanced Antibacterial Property of Facet-Engineered TiO2 Nanosheet in Presence and Absence of Ultraviolet Irradiation

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TiO 2 -based photocatalytic disinfection of microbes in aqueous media: A review

Cited by 351 publications

References 48 publications

Mo doped TiO2: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Mo doped TiO2: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Two‐dimensional nanomaterials for photocatalytic water disinfection: recent progress and future challenges

Enhanced Antibacterial Property of Facet-Engineered TiO2 Nanosheet in Presence and Absence of Ultraviolet Irradiation

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Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity