A review of the influence of humidity on photocatalytic decomposition of gaseous pollutants on TiO<sub>2</sub>‐based catalysts

Zhang, Lianfeng; Moralejo, Carol; Anderson, William A.

doi:10.1002/cjce.23652

Cited by 37 publications

(14 citation statements)

References 102 publications

(67 reference statements)

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“…This range agrees with the reported experimental data of 25, 45 and 90 mmol represented with the green, blue, and yellow color cross marks. Thus, these results are in line with claims from others [62][63][64] showing that keeping air relative humidity in the 20-50% range results in a lack of influence of humidity on photocatalytic activity. Therefore, under the proposed conditions, one can process a VOC air contaminated stream with a 30-50% RH.…”

Section: Conflicts Of Interestsupporting

confidence: 92%

Photocatalytic Conversion of Organic Pollutants in Air: Quantum Yields Using a Silver/Nitrogen/TiO2 Mesoporous Semiconductor under Visible Light

et al. 2021

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This research studies the photocatalytic conversion of methanol (25–90 µmol/L range) as a volatile organic compound (VOC) surrogate into CO2, using a N/Ag/TiO2 photocatalyst under visible light irradiation in a Photo-CREC Air unit. The N/Ag/TiO2 mesh supported photocatalyst is prepared via the solvothermal method. While the bare-TiO2 is inactive under visible light, the N/Ag/TiO2 2 wt.% loaded stainless-steel woven mesh displays 35% quantum yields, with 80% absorbed photons and 60% methanol conversion in a 110 min irradiation period. Results obtained are assigned to silver surface plasmon resonance, silver and nitrogen species synergistic impacts on band gap, and their influence on particle agglomerate size and semiconductor acidity. The determined quantum yields under visible light in a Photo-CREC Air unit, are the highest reported in the technical literature, that these authors are aware of, with this opening unique opportunity for the use of visible light for the purification of air from VOC contaminants.

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Section: Conflicts Of Interestsupporting

confidence: 92%

Photocatalytic Conversion of Organic Pollutants in Air: Quantum Yields Using a Silver/Nitrogen/TiO2 Mesoporous Semiconductor under Visible Light

et al. 2021

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“…This expression was used to determine the kinetics of heteroge neous catalytic processes. [78][79][80][81][82] The L-H model is described as follows:…”

Section: Evaluation Of Kinetic Parameters Of the Most Active Photocatalytic Materials 1cu-tio 2 -600mentioning

confidence: 99%

Synergistic Effect of Cu,F‐Codoping of Titanium Dioxide for Multifunctional Catalytic and Photocatalytic Studies

Díaz-Sánchez

Murgu

Díaz-García

et al. 2021

Advanced Sustainable Systems

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This material has been used as a photo catalyst for water splitting since 1972 when Fujishima and Honda reported its ability to generate hydrogen and oxygen from water molecules. [1] Titanium dioxide is normally used in advanced oxidation processes, [2] in systems capable of elimi nating a wide variety of chemicals in air and water, as well as solar fuel production (such as H 2 ). [3,4] The photoactivated pro cesses of titanium dioxidebased photo catalysts are achieved when the irradiation energy is higher than its band gap. This generates electrons in the conduction band and holes in valence band, which rapidly migrate to the TiO 2 surface and provoke the generation of extremely reactive spe cies. For example, H 2 O 2 and the radicals OH • , O 2-• formed after the electron and the holes reach the external surface of titanium dioxide, are very important for the photodecomposition of organic pol lutants to CO 2 and H 2 O, which is true for the most active titanium dioxidebased materials. [5,6] The band gap value has a direct impact on the rate of electronhole (e --h +) recombination during the photocatalytic processes. In the case of titanium dioxide, the relatively large band gap, means there is a slow recombination rate compared to most of the other photocatalysts. [7] Three main phases are present in TiO 2 : 1) Anatase (tetrag onal, a = b = 3.785 Å, c = 9.54 Å), 2) brookite (orthorhombic, a = 5.143 Å, b = 5.456 Å, c = 9.182 Å), and 3) rutile (tetragonal a = b = 4.593 Å, c = 2.959 Å). [8,9] The thermodynamically meta stable phases, anatase, and brookite, irrevocably pass into the stable phase of rutile at high temperatures. [7] Each of these phases show its own morphological characteristics and band gap value: In the case of anatase the band gap is of 3.2 eV, while rutile and brookite have band gaps of 3.0 and 3.3 eV, respec tively. In general, anatase shows the most attractive photocata lytic behavior due to its versatility and textural properties. [10][11][12] However, the anatase phase, due to its band gap, can only be activated by UV light, which accounts for approximately only 4% of the solar spectrum. Thus, in order to stabilize the anatase phase at elevated temperatures, and to utilize UV and visible light for photocatalysis, chemical modifiers and dopants are generally employed for the modification of the photocatalytic Titanium dioxide nanomaterials with improved catalytic and photo catalytic properties through codoping with copper and fluorine are synthesized and contain optimal textural and compositional properties, which are not possible without doping or with a single doping of Cu or F separately. The codoped systems promote the generation of a synergistic effect increasing activity of the systems in photocatalytic processes of both potential environmental or energy interest. The photocatalysts show very effective degradations of industrial and emerging contaminants such as ciprofloxacin (80% degradation) and naproxen (72% degradation) using UV light (300 W) in short periods of up to 15 min. An ad...

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“…Although the adsorption of toluene on the TiO 2 surface was greater for the SD method, the reaction rate was lower for SA and SG methods. This behavior was attributed to a strong competition between adsorbed water and pollutant (e.g., toluene) ( Zhang et al, 2020 ). Therefore, the adsorbed water that remained on the sample surface after the preparation and drying process was analyzed using a TGA technique.…”

Section: Resultsmentioning

confidence: 99%

Aerosol-Assisted Deposition for TiO2 Immobilization on Photocatalytic Fibrous Filters for VOC Degradation

et al. 2022

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Atomization and spraying are well-established methods for the production of submicrometer- and micrometer- sized powders. In addition, they could be of interest to the immobilization of photocatalytic nanoparticles onto supports because they enable the formation of microporous films with photocatalytic activity. Here, we provide a comparison of aerosol-assisted immobilization methods, such as spray-drying (SD), spray atomization (SA), and spray gun (SG), which were used for the deposition of TiO2 dispersions onto fibrous filter media. The morphology, microstructure, and electronic properties of the structures with deposited TiO2 were characterized by SEM and TEM, BET and USAXS, and UV-Vis spectrometry, respectively. The photocatalytic performances of the functionalized filters were evaluated and compared to the benchmark dip-coating method. Our results showed that the SG and SA immobilization methods led to the best photocatalytic and operational performance for the degradation of toluene, whereas the SD method showed the lowest degradation efficiency and poor stability of coating. We demonstrated that TiO2 sprays using the SG and SA methods with direct deposition onto filter media involving dispersed colloidal droplets revealed to be promising alternatives to the dip-coating method owing to the ability to uniformly cover the filter fibers. In addition, the SA method allowed for fast and simple control of the coating thickness as the dispersed particles were continuously directed onto the filter media without the need for repetitive coatings, which is common for the SG and dip-coating methods. Our study highlighted the importance of the proper immobilization method for the efficient photocatalytic degradation of VOCs.

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A review of the influence of humidity on photocatalytic decomposition of gaseous pollutants on TiO₂‐based catalysts

Cited by 37 publications

References 102 publications

Photocatalytic Conversion of Organic Pollutants in Air: Quantum Yields Using a Silver/Nitrogen/TiO2 Mesoporous Semiconductor under Visible Light

Photocatalytic Conversion of Organic Pollutants in Air: Quantum Yields Using a Silver/Nitrogen/TiO2 Mesoporous Semiconductor under Visible Light

Synergistic Effect of Cu,F‐Codoping of Titanium Dioxide for Multifunctional Catalytic and Photocatalytic Studies

Aerosol-Assisted Deposition for TiO2 Immobilization on Photocatalytic Fibrous Filters for VOC Degradation

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A review of the influence of humidity on photocatalytic decomposition of gaseous pollutants on TiO2‐based catalysts

Cited by 37 publications

References 102 publications

Photocatalytic Conversion of Organic Pollutants in Air: Quantum Yields Using a Silver/Nitrogen/TiO2 Mesoporous Semiconductor under Visible Light

Photocatalytic Conversion of Organic Pollutants in Air: Quantum Yields Using a Silver/Nitrogen/TiO2 Mesoporous Semiconductor under Visible Light

Synergistic Effect of Cu,F‐Codoping of Titanium Dioxide for Multifunctional Catalytic and Photocatalytic Studies

Aerosol-Assisted Deposition for TiO2 Immobilization on Photocatalytic Fibrous Filters for VOC Degradation

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A review of the influence of humidity on photocatalytic decomposition of gaseous pollutants on TiO₂‐based catalysts