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Djellabi, R. Photocatalysis for Air Purification. Encyclopedia. Available online: https://encyclopedia.pub/entry/9688 (accessed on 27 July 2024).
Djellabi R. Photocatalysis for Air Purification. Encyclopedia. Available at: https://encyclopedia.pub/entry/9688. Accessed July 27, 2024.
Djellabi, Ridha. "Photocatalysis for Air Purification" Encyclopedia, https://encyclopedia.pub/entry/9688 (accessed July 27, 2024).
Djellabi, R. (2021, May 17). Photocatalysis for Air Purification. In Encyclopedia. https://encyclopedia.pub/entry/9688
Djellabi, Ridha. "Photocatalysis for Air Purification." Encyclopedia. Web. 17 May, 2021.
Photocatalysis for Air Purification
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This entry is adapted from the peer-reviewed paper 10.3390/catal11050562

Photocatalysis since a long time has been recognized  as a eco-technology to fight air pollution. It is focused  on the generation of reactive oxygen species (ROSs) under light on the surface of a photocatalytic material. It could be applied in different manners such as for the purification of industrial polluted air, photoconversion of toxic gas into valuable products, self-cleaning systems, photocatalytic filters, etc. However, it faces some technological issues limiting its wide application in real-world.  

photocatalysis reactors Air purification Disinfection Environmental remediation

1. Introduction

For more than three decades, the scientific community has devoted a great deal of effort to developing photocatalytic processes for the removal of a range of air pollutants [1][2][3][4][5][6]. Photocatalysis was demonstrated to be effective for the removal of pollutants in gas phase at relatively low concentrations [7]. Different photocatalytic materials and photoreactors have been proposed [3][7][8][9]. However, similar to the case of photocatalytic water treatment [10], the process scale-up for the photocatalytic air purification is still an open challenge [11].
When it comes to the application of photocatalysis in a real air system, different approaches can be envisaged:
(i) Photocatalytic self-cleaning and antimicrobial materials to be used in indoor/outdoor areas: Under natural solar light (outdoor) or LED irradiation (indoor), the photoactive self-cleaning materials can initiate photocatalytic reactions able to clean continuously their surface and/or treat air pollutants [12][13][14]. This system is very promising and has received a lot attention from the industrial community [15][16][17]. Numerous types of self-cleaning coatings and building materials have been developed and commercialized for both indoor and outdoor applications. For instance, Bianchi et al. [17][18][19] reported a novel digital printing technology for the coating of tiles by visible light-responsive Ag nanoparticle-decorated TiO2 (Figure 1). This scalable technology allows obtaining a homogenous coating without the loss of photoactivity.
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Figure 1. Photocatalytic self-cleaning industrial ceramics based on Ag nanoparticle-decorated TiO2 (inset) (by IrisCeramica Group—Italy) for the purification of contaminated air and bacteria inactivation, reproduced with permission from reference [19].
(ii) Photocatalytic purification of contaminated air in indoor, small spaces, such as aircraft cabins [20] and cold rooms [21]: while some air purifier devices based on photocatalytic materials are already on the market, this technology has some drawbacks. Since toxic by-products can be formed during the photocatalytic process if contact times are not properly tuned, the undesired accumulation of toxic by-products in an enclosed environment can occur [22][23][24].
(iii) Photocatalytic reactors for the direct purification of industrial exhausts: photocatalytic reactors for this application have some scale-up issues and the gap between research at a laboratory scale and industrial needs is still substantial.
(iv) Giant solar photoreactors for CO2 reduction have been suggested as a possible strategy against climate change [25]: this approach has the additional benefit of producing value-added chemicals or fuels from the reduction process. However, research in this field is still in the early stages.
New applications are also emerging. In this respect, Horváth et al. [26] recently reported a photocatalytic mask filter based on TiO2 nanowires, which can be used as a protection against airborne viruses, including COVID-19, and can be photocatalytically sanitized under UV irradiation (Figure 2). Li et al. [27] fabricated a photocatalytic metal–organic framework (MOF)-based personal mask that can be self-disinfected under visible light.
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Figure 2. Photocatalytic air filters based on TiO2 nanowires, (a) photocatalytic action for the disinfection of microbial species, (b) photograph of photocatalytic mask-based filter, (c) mask disinfection under 365 nm. Reproduced with permission from [26].

2. Photocatalytic Reactors for Air Treatment

A successful photoreactor ensures, on one hand, an excellent interaction between the gas pollutants and the immobilized photocatalyst by an enhanced surface-to-volume ratio and, on the other hand, an excellent irradiation of the photocatalyst surface [9][28][29][30][31].
Mass transfer and contact time are key parameters in photocatalytic air processing, since in air systems only adsorbed pollutants can undergo degradation by direct oxidation by positive holes or surface photoproduced ROS. While this issue is generally less felt in lab scale batch reactors, where contact times range from seconds to minutes [32], the design of photocatalytic reactors for treating large air volumes requires a careful optimization of mass transfer issues [33] in order to achieve a fast degradation of pollutants without the accumulation of undesired by-products. In real applications, high flow rates are needed to maximize mass transfer, but this comes at the cost of decreasing the contact time between the pollutant and the photocatalyst surface to less than 1 s, which often results in an incomplete degradation of the pollutant. To solve this problem, different strategies have been reported, including modifications in the reactor geometry to decrease face velocity [24] or increases in the photocatalytic surface area and irradiance [28]. It should be noted that the ideal contact time depends on the adsorption affinity between the reactants and the photocatalyst/support [34].
Costa Filho et al. [28] proposed a micro-meso-structured photoreactor for the removal of gas phase n-decane by simulated solar light (Figure 3). The adopted geometry allowed a uniform irradiance of the TiO2 photocatalyst, yielding a degradation rate of 6.6 mmol·m−3·s−1 and no loss of activity after 72 h of consecutive use.
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Figure 3. Schematic representation and photograph of the NETmix Microscale photoreactor with LED light for n-decane photo-oxidation in gas phase, reproduced with permission from [28], Copyright 2019, Elsevier.
Fluidized bed photoreactors have also shown a great potential for the photocatalytic purification of contaminated air. Light irradiation can be external (Figure 4e) [35][36] or internal (Figure 74f) [37], and can also utilize LED lamps [34]. However, the leaching of photocatalysts from the bed was observed in this type of reactor [38].
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Figure 4. (a) Schematic representation of commercial-scale monolith-based reactor for air purification, reproduced with permission from reference [1]. (b) Square-channeled honeycomb monoliths, reproduced with permission from reference [39]. (c) TiO2-coated transparent monolith for air purification, reproduced with permission from reference [40]. (d) Photographs of monolith reactor equipped with light-emitting fibers inserted into the monoliths, for multiphase photocatalytic treatment, adapted with permission from [41]. (e–f) Fluidized bed photoreactor with external (e) and internal (f) irradiation, reproduced with permission from reference [38]. (g) Tubular flow photoreactor enclosing lamps with internal-wall-coated photocatalyst, reproduced with permission from reference [38]. (h) Alumina reticulated foam monoliths for the use in a photocatalytic tubular flow photoreactor, reproduced with permission from reference [39]. (i) Multi-walled tubular reactor flow photoreactor for enhanced mass transfer, reproduced with permission from reference [38].
Very recently, Saoud et al. reported a pilot-scale reactor for gas-phase VOC remediation and Escherichia coli inactivation based on a photocatalytic textile, based on optical fiber irradiated by UV LED [34]. A 66% degradation of 5 mg·m−3 butane-2,3-dione was measured when the system operated at 2 m3·h−1.
More conventional geometries adopting honeycomb monoliths have already been commercialized for the photocatalytic purification of air (Figure 4a,b). Dijk et al. [41] designed an internally illuminated honeycomb-based photoreactor for air treatment (Figure 4d) with high surface-to-volume ratio for air purification. This reactor is made for multiphase use [29], wherein the photocatalyst is coated via sol-gel in the inner walls of monolith channels. However, the drawback of this system is the need for separated illumination of each monolith channel. Transport cellulosic monoliths allow the penetration of artificial or natural solar light through all monolith channels (Figure 4c) [42][39][43][40][44].
Another reactor geometry for air treatment is tubular flow photoreactors enclosing lamps (Figure 4g,h) [45][46]; for enhanced mass transfer and surface-to-volume ratio, multi-wall-based reactors were constructed as shown in (Figure 4i) [47][48][49].
Hybrid techniques combining photocatalysis and other AOPs hold promise for the treatment of large volumes of air due to their synergistic effects. Filho et al. [50] combined O3/UV/TiO2 for the oxidation of VOC in air streams in a NETmix micro-photoreactor system (Figure 5a). While single ozonation exhibited fast oxidation toward n-decane but very slow mineralization, the hybrid system O3/UV/TiO2 showed a synergistic removal and mineralization. Zadi et al. [21] combined non-thermal plasma and photocatalysis for the oxidation of propionic acid and benzene in refrigerated food chambers (Figure 5b). By the use of photocatalysis as a single process, the authors reported serious gas toxicity. The combination of photocatalysis with non-thermal plasma overcomes such a toxicity issue, and on top of that, an enhanced photocatalytic efficiency was observed together with an excellent regeneration of the photocatalytic surface.
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Figure 5. (a) Scheme of cold plasma and TiO2 combined system for the purification of ethanol-contaminated air, reproduced with permission from reference [51], Copyright 2007, American Chemical Society. (b) Combination of photocatalysis with non-thermal dielectric barrier discharge (DBD) plasma for the oxidation of propionic acid and benzene in refrigerated food chambers, reproduced with permission from reference [21], Copyright 2020, Elsevier.

3. Tests in Realistic Conditions

The efficiency of air purification by photocatalysis depends on a series of operational parameters and environmental conditions. However, comparatively few studies have considered these all-important parameters in photocatalytic tests [24][28] and even fewer have reported actual field tests of pilot-scale reactors [52].
First of all, the role of relative humidity should be considered. Water vapor is a ubiquitous component of air and industrial exhaust. The relative humidity of the treated effluent can vary greatly depending on the environmental conditions and process parameters, but it is generally present in concentrations far higher than those of the pollutants. Water vapor is also known to greatly affect the photocatalytic process [32]. However, there is no consensus on the effect of air humidity on the photocatalytic performance [34]. Water vapor seems to play different, conflicting roles in gas-phase photocatalysis and the overall beneficial or detrimental effect depends on parameters such as the type of pollutant and its concentration, the photocatalyst adsorption capacity and air relative humidity. It is worth mentioning that water competes for adsorption at the photocatalyst active sites, which can lead to a detrimental effect in terms of pollutant adsorption and, hence, photocatalytic activity [52]. Competition for adsorption between the reaction intermediates and water can also result in a detrimental effect in terms of mineralization [52]. On the other hand, water can react with photogenerated charges to generate reactive radicals, promoting the photocatalytic degradation. The injection of water vapor can enhance the formation of HO• species on the surface of the photocatalyst [53]. Conversely, in a dry air system, the yield of photoproduced ROS can be reduced and it is mostly related to O2−• species.
Air samples also contain a mixture of pollutants, generally with individual concentrations in the order of the (parts-per-billion-volume) ppbv. Most literature studies have involved photocatalytic tests with a single gas pollutant, often with concentrations in the ppm range. Higher pollutant concentrations are generally associated with improved reaction rates (until the rate reaches its plateau), poorer efficiency of removal and lower mineralization [34]. In the case of pollutant mixtures, the individual components are generally simultaneously degraded when the individual concentrations are in the ppbv range. However, the co-presence of some species, such as SO2 [52] and NOx [52], can lead to detrimental effects on the degradation of VOCs.

4. Photocatalyst Deactivation

The deactivation of photocatalyst systems is a serious issue that should be solved for a continuous processing [54]. It takes place during the photocatalytic reaction as a result of irreversible adsorption of recalcitrant by-products or site blocking by carbonaceous residues or dust particles on the surface [41]. In gas-phase photocatalysis, deactivation is a more pressing concern than it is in liquid phase, as there is no water solvent to help to remove products and intermediates from the surface.
Throughout the literature, the deactivation process has depended mainly on the characteristics of the photocatalysts, the type and concentration of pollutants. Deactivation is most severe in the presence of aromatic compounds [55][56]; however, it has been reported for a wide range of species [57]. For instance, van Dijk et al. reported photocatalyst deactivation within 80 min of photocatalytic operation for the oxidation of cyclohexane [41]. Despite the importance of this topic for the commercial application of photocatalytic technologies, comparatively few studies have investigated the mechanisms of deactivation, regeneration and the photocatalyst lifetime.
Several strategies to reactivate the photocatalyst have been proposed, including treatment with water vapor [41], high temperature treatment [41][57], oxidation with H2O2 [57] and UV irradiation [58]. The use of a more oxidizing atmosphere and better mass transfer have been reported to slow down deactivation [56]. Simple washing with water or reagents and organic solvents can be used also to regenerate the deactivated photocatalysts. Djellabi et al. reported the deactivation of TiO2 P25 during the photocatalytic reduction of Cr(VI) under natural solar light [59]. It was found that 39% of reduced Cr(VI) was deposited as Cr(III) on the surface of P25, which turned the surface of P25 green. The regeneration of the P25 surface was carried out by the sequential extraction, and the leaching of Cr(III) was found to be 90% and 42% after three washings by citric acid and EDTA, respectively. However, the regeneration of photocatalysts at large scale is not recommended because it is time consuming and not cost effective. The use of vacuum ultraviolet or non-thermal plasma have been suggested to prevent the deactivation of photocatalysts or to enhance their lifetime. In fact, the application of the last two routes is quite hard at large scale for the treatment of large volumes. Engineering of photocatalytic materials may reduce the deactivation process. Chen et al. reported that the deactivation of TiO2 P25 during the decomposition of VOCs in air phase is due to the adsorption of benzaldehyde intermediate on P25 surface, which is characterized by the high reaction energy of the aromatic ring opening [60]. The deactivation causes a dramatic decrease in VOC reduction from 72.4% to 12.3% with prolonged time. However, under the same conditions, β-Ga2O3 remains photocatalytically active along with the experiment without a decrease in the efficiency. The authors reported that β-Ga2O3 is more effective for opening the aromatic ring of intermediates, which prevents the deactivation of the photoactive surface.
Combining photocatalysis with another AOP generally promotes the lifetime of the photocatalyst. Zadi et al. [21] reported that the introduction of non-thermal plasma to the photocatalytic system can lead to continuous regeneration of the photocatalyst in air system. It was found by Ribeiro et al. [61] that addition of ozone allows the use of TiO2 without deactivation up to 77 h.

References

  1. Hay, S.O.; Obee, T.; Luo, Z.; Jiang, T.; Meng, Y.; He, J.; Murphy, S.C.; Suib, S. The viability of photocatalysis for air purification. Molecules 2015, 20, 1319–1356.
  2. Nath, R.K.; Zain, M.F.M.; Jamil, M. An environment-friendly solution for indoor air purification by using renewable photocatalysts in concrete: A review. Renew. Sustain. Energy Rev. 2016, 62, 1184–1194.
  3. Paz, Y. Photocatalytic treatment of air: From basic aspects to reactors. Adv. Chem. Eng. 2009, 36, 289–336.
  4. Peral, J.; Domènech, X.; Ollis, D.F. Heterogeneous photocatalysis for purification, decontamination and deodorization of air. J. Chem. Technol. Biotechnol. 1997, 70, 117–140.
  5. Demeestere, K.; Dewulf, J.; Van Langenhove, H. Heterogeneous photocatalysis as an advanced oxidation process for the abatement of chlorinated, monocyclic aromatic and sulfurous volatile organic compounds in air: State of the art. Crit. Rev. Environ. Sci. Technol. 2007, 37, 489–538.
  6. Escobedo, S.; de Lasa, H. Photocatalysis for air treatment processes: Current technologies and future applications for the removal of organic pollutants and viruses. Catalysts 2020, 10, 966.
  7. Boyjoo, Y.; Sun, H.; Liu, J.; Pareek, V.K.; Wang, S. A review on photocatalysis for air treatment: From catalyst development to reactor design. Chem. Eng. J. 2017, 310, 537–559.
  8. Paz, Y. Application of TiO2 photocatalysis for air treatment: Patents’ overview. Appl. Catal. B Environ. 2010, 99, 448–460.
  9. Birnie, M.; Riffat, S.; Gillott, M. Photocatalytic reactors: Design for effective air purification. Int. J. Low Carbon Technol. 2006, 1, 47–58.
  10. Garcia-Muñoz, P.; Fresno, F.; Lefevre, C.; Robert, D.; Keller, N. Highly robust La1-xTixFeO3 dual catalyst with combined photocatalytic and photo-CWPO activity under visible light for 4-chlorophenol removal in water. Appl. Catal. B Environ. 2020, 262, 118310.
  11. Costarramone, N.; Cantau, C.; Desauziers, V.; Pécheyran, C.; Pigot, T.; Lacombe, S. Photocatalytic air purifiers for indoor air: European standard and pilot room experiments. Environ. Sci. Pollut. Res. 2017, 24, 12538–12546.
  12. Binas, V.; Venieri, D.; Kotzias, D.; Kiriakidis, G. Modified TiO2 based photocatalysts for improved air and health quality. J. Mater. 2017, 3, 3–16.
  13. De Niederhausern, S.; Bondi, M.; Bondioli, F. Self-cleaning and antibacteric ceramic tile surface. Int. J. Appl. Ceram. Technol. 2013, 10, 949–956.
  14. Portela, R.; Tessinari, R.F.; Suarez, S.; Rasmussen, S.B.; Hernández-Alonso, M.D.; Canela, M.C.; Avila, P.; Sánchez, B. Photocatalysis for continuous air purification in wastewater treatment plants: From lab to reality. Environ. Sci. Technol. 2012, 46, 5040–5048.
  15. Chen, J.; Poon, C. Photocatalytic construction and building materials: From fundamentals to applications. Build. Environ. 2009, 44, 1899–1906.
  16. Bianchi, C.L.; Pirola, C.; Stucchi, M.; Sacchi, B.; Cerrato, G.; Morandi, S.; Di Michele, A.; Carletti, A.; Capucci, V. A New Frontier of Photocatalysis Employing Micro-Sized TiO2: Air/Water Pollution Abatement and Self-Cleaning/Antibacterial Applications; Intech Open: London, UK, 2016; ISBN 9535124846.
  17. Bianchi, C.L.; Cerrato, G.; Bresolin, B.M.; Djellabi, R.; Rtimi, S. Digitally printed AgNPs doped TiO2 on commercial porcelain-grès tiles: Synergistic effects and continuous photocatalytic antibacterial activity. Surfaces 2020, 3, 11–25.
  18. Cerrato, G.; Galli, F.; Boffito, D.C.; Operti, L.; Bianchi, C.L. Correlation preparation parameters/activity for microTiO2 decorated with SilverNPs for NOx photodegradation under LED light. Appl. Catal. B Environ. 2019, 253, 218–225.
  19. Bianchi, C.L.; Cerrato, G.; Pirola, C.; Galli, F.; Capucci, V. Photocatalytic porcelain grés large slabs digitally coated with AgNPs-TiO2. Environ. Sci. Pollut. Res. 2019, 26, 36117–36123.
  20. Martínez-Montelongo, J.H.; Medina-Ramírez, I.E.; Romo-Lozano, Y.; Zapien, J.A. Development of a sustainable photocatalytic process for air purification. Chemosphere 2020, 257, 127236.
  21. Zadi, T.; Azizi, M.; Nasrallah, N.; Bouzaza, A.; Maachi, R.; Wolbert, D.; Rtimi, S.; Assadi, A.A. Indoor air treatment of refrigerated food chambers with synergetic association between cold plasma and photocatalysis: Process performance and photocatalytic poisoning. Chem. Eng. J. 2020, 382, 122951.
  22. Zhong, L.; Haghighat, F. Photocatalytic air cleaners and materials technologies–abilities and limitations. Build. Environ. 2015, 91, 191–203.
  23. Farhanian, D.; Haghighat, F.; Lee, C.-S.; Lakdawala, N. Impact of design parameters on the performance of ultraviolet photocatalytic oxidation air cleaner. Build. Environ. 2013, 66, 148–157.
  24. Destaillats, H.; Sleiman, M.; Sullivan, D.P.; Jacquiod, C.; Sablayrolles, J.; Molins, L. Key parameters influencing the performance of photocatalytic oxidation (PCO) air purification under realistic indoor conditions. Appl. Catal. B Environ. 2012, 128, 159–170.
  25. Kiesgen de_Richter, R.; Ming, T.; Caillol, S. Fighting global warming by photocatalytic reduction of CO2 using giant photocatalytic reactors. Renew. Sustain. Energy Rev. 2013, 19, 82–106.
  26. Horváth, E.; Rossi, L.; Mercier, C.; Lehmann, C.; Sienkiewicz, A.; Forró, L. Photocatalytic nanowires-based air filter: Towards reusable protective masks. Adv. Funct. Mater. 2020, 30, 2004615.
  27. Li, P.; Li, J.; Feng, X.; Li, J.; Hao, Y.; Zhang, J.; Wang, H.; Yin, A.; Zhou, J.; Ma, X. Metal-organic frameworks with photocatalytic bactericidal activity for integrated air cleaning. Nat. Commun. 2019, 10, 1–10.
  28. Da Costa Filho, B.M.; Araujo, A.L.P.; Padrão, S.P.; Boaventura, R.A.R.; Dias, M.M.; Lopes, J.C.B.; Vilar, V.J.P. Effect of catalyst coated surface, illumination mechanism and light source in heterogeneous TiO2 photocatalysis using a mili-photoreactor for n-decane oxidation at gas phase. Chem. Eng. J. 2019, 366, 560–568.
  29. Du, P.; Carneiro, J.T.; Moulijn, J.A.; Mul, G. A novel photocatalytic monolith reactor for multiphase heterogeneous photocatalysis. Appl. Catal. A Gen. 2008, 334, 119–128.
  30. Romero-Vargas Castrillón, S.; De Lasa, H.I. Performance evaluation of photocatalytic reactors for air purification using computational fluid dynamics (CFD). Ind. Eng. Chem. Res. 2007, 46, 5867–5880.
  31. Whyte, H.E. Evaluation of the Performance of Photocatalytic Systems for the Treatment of Indoor Air in Medical Environments. Ph.D. Thesis, Ecole Nationale Supérieure Mines-Télécom Atlantique, Nantes, France, 2018.
  32. Lyu, J.; Zhu, L.; Burda, C. Considerations to improve adsorption and photocatalysis of low concentration air pollutants on TiO2. Catal. Today 2014, 225, 24–33.
  33. Thomson, C.G.; Lee, A.-L.; Vilela, F. Heterogeneous photocatalysis in flow chemical reactors. J. Org. Chem. 2020, 16, 1495–1549.
  34. Mamaghani, A.H.; Haghighat, F.; Lee, C.-S. Photocatalytic oxidation technology for indoor environment air purification: The state-of-the-art. Appl. Catal. B Environ. 2017, 203, 247–269.
  35. Zhao, J.; Yang, X. Photocatalytic oxidation for indoor air purification: A literature review. Build. Environ. 2003, 38, 645–654.
  36. Sannino, D.; Vaiano, V.; Ciambelli, P.; Eloy, P.; Gaigneaux, E.M. Avoiding the deactivation of sulphated MoOx/TiO2 catalysts in the photocatalytic cyclohexane oxidative dehydrogenation by a fluidized bed photoreactor. Appl. Catal. A Gen. 2011, 394, 71–78.
  37. Cheng, Z.; Quan, X.; Xiang, J.; Huang, Y.; Xu, Y. Photocatalytic degradation of bisphenol A using an integrated system of a new gas-liquid-solid circulating fluidized bed reactor and micrometer Gd-doped TiO2 particles. J. Environ. Sci. 2012, 24, 1317–1326.
  38. Ren, H.; Koshy, P.; Chen, W.-F.; Qi, S.; Sorrell, C.C. Photocatalytic materials and technologies for air purification. J. Hazard. Mater. 2017, 325, 340–366.
  39. Raupp, G.B.; Alexiadis, A.; Hossain, M.M.; Changrani, R. First-principles modeling, scaling laws and design of structured photocatalytic oxidation reactors for air purification. Catal. Today 2001, 69, 41–49.
  40. Lopes, F.V.S.; Miranda, S.M.; Monteiro, R.A.R.; Martins, S.D.S.; Silva, A.M.T.; Faria, J.L.; Boaventura, R.A.R.; Vilar, V.J.P. Perchloroethylene gas-phase degradation over titania-coated transparent monoliths. Appl. Catal. B Environ. 2013, 140, 444–456.
  41. Van Dijk, V.H.A.; Simmelink, G.; Mul, G. The influence of water vapour on the photocatalytic oxidation of cyclohexane in an internally illuminated monolith reactor. Appl. Catal. A Gen. 2014, 470, 63–71.
  42. Marinho, B.A.; Cristóvão, R.O.; Djellabi, R.; Loureiro, J.M.; Boaventura, R.A.R.; Vilar, V.J.P. Photocatalytic reduction of Cr (VI) over TiO2-coated cellulose acetate monolithic structures using solar light. Appl. Catal. B Environ. 2017, 203, 18–30.
  43. Monteiro, R.A.R.; Miranda, S.M.; Rodrigues-Silva, C.; Faria, J.L.; Silva, A.M.T.; Boaventura, R.A.R.; Vilar, V.J.P. Gas phase oxidation of n-decane and PCE by photocatalysis using an annular photoreactor packed with a monolithic catalytic bed coated with P25 and PC500. Appl. Catal. B Environ. 2015, 165, 306–315.
  44. Portela, R. Eliminación Fotocatalítica de H2S en Aire Mediante TiO2 Soportado Sobre Sustratos Transparentes en el UV-A; Universidad de Santiago de Compostela: A Coruña, Spain, 2009; ISBN 8478346104.
  45. Zacarías, S.M.; Manassero, A.; Pirola, S.; Alfano, O.M.; Satuf, M.L. Design and performance evaluation of a photocatalytic reactor for indoor air disinfection. Environ. Sci. Pollut. Res. 2020, 1–9.
  46. Mo, J.; Zhang, Y.; Xu, Q.; Lamson, J.J.; Zhao, R. Photocatalytic purification of volatile organic compounds in indoor air: A literature review. Atmos. Environ. 2009, 43, 2229–2246.
  47. Imoberdorf, G.E.; Cassano, A.E.; Alfano, O.M.; Irazoqui, H.A. Modeling of a multiannular photocatalytic reactor for perchloroethylene degradation in air. AIChE J. 2006, 52, 1814–1823.
  48. Imoberdorf, G.E.; Cassano, A.E.; Irazoqui, H.A.; Alfano, O.M. Simulation of a multi-annular photocatalytic reactor for degradation of perchloroethylene in air: Parametric analysis of radiative energy efficiencies. Chem. Eng. Sci. 2007, 62, 1138–1154.
  49. Van Walsem, J.; Verbruggen, S.W.; Modde, B.; Lenaerts, S.; Denys, S. CFD investigation of a multi-tube photocatalytic reactor in non-steady-state conditions. Chem. Eng. J. 2016, 304, 808–816.
  50. Da Costa Filho, B.M.; Silva, G.V.; Boaventura, R.A.R.; Dias, M.M.; Lopes, J.C.B.; Vilar, V.J.P. Ozonation and ozone-enhanced photocatalysis for VOC removal from air streams: Process optimization, synergy and mechanism assessment. Sci. Total Environ. 2019, 687, 1357–1368.
  51. Taranto, J.; Frochot, D.; Pichat, P. Combining cold plasma and TiO2 photocatalysis to purify gaseous effluents: A preliminary study using methanol-contaminated air. Ind. Eng. Chem. Res. 2007, 46, 7611–7614.
  52. Maurer, D.L.; Koziel, J.A. On-farm pilot-scale testing of black ultraviolet light and photocatalytic coating for mitigation of odor, odorous VOCs, and greenhouse gases. Chemosphere 2019, 221, 778–784.
  53. Sun, S.; Ding, J.; Bao, J.; Gao, C.; Qi, Z.; Li, C. Photocatalytic oxidation of gaseous formaldehyde on TiO2: An in situ DRIFTS study. Catal. Lett. 2010, 137, 239–246.
  54. Xu, Q.; Zhang, L.; Yu, J.; Wageh, S.; Al-Ghamdi, A.A.; Jaroniec, M. Direct Z-scheme photocatalysts: Principles, synthesis, and applications. Mater. Today 2018, 21, 1042–1063.
  55. Ardizzone, S.; Bianchi, C.L.; Cappelletti, G.; Naldoni, A.; Pirola, C. Photocatalytic degradation of toluene in the gas phase: Relationship between surface species and catalyst features. Environ. Sci. Technol. 2008, 42, 6671–6676.
  56. Weon, S.; Choi, W. TiO2 nanotubes with open channels as deactivation-resistant photocatalyst for the degradation of volatile organic compounds. Environ. Sci. Technol. 2016, 50, 2556–2563.
  57. Walenta, C.A.; Kollmannsberger, S.L.; Kiermaier, J.; Winbauer, A.; Tschurl, M.; Heiz, U. Ethanol photocatalysis on rutile TiO2(110): The role of defects and water. Phys. Chem. Chem. Phys. 2015, 49, 22809–22814.
  58. Piera, E.; Ayllón, J.A.; Doménech, X.; Peral, J. TiO2 deactivation during gas-phase photocatalytic oxidation of ethanol. Catal. Today 2002, 76, 259–270.
  59. Djellabi, R.; Ghorab, F.M.; Nouacer, S.; Smara, A.; Khireddine, O. Cr(VI) photocatalytic reduction under sunlight followed by Cr(III) extraction from TiO2 surface. Mater. Lett. 2016, 176, 106–109.
  60. Chen, P.; Cui, W.; Wang, H.; Dong, X.; Li, J.; Sun, Y.; Zhou, Y.; Zhang, Y.; Dong, F. The importance of intermediates ring-opening in preventing photocatalyst deactivation during toluene decomposition. Appl. Catal. B Environ. 2020, 272, 118977.
  61. Ribeiro, B.M.B.; Fujimoto, T.M.; Bricio, B.G.M.; Doubek, U.L.R.; Tomaz, E. Gas-phase aromatic compounds degradation by a partially TiO2 coated photoreactor assisted with ozone. Process Saf. Environ. Prot. 2020, 135, 265–272.
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Subjects: Chemistry, Analytical
Contributor MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to https://encyclopedia.pub/register :
Ridha Djellabi
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Entry Collection: Environmental Sciences
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Update Date: 17 May 2021
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