Air Depollution Research Articles

Washable oil-coated structured support for passive outdoor particulate matters trapping

Direct outdoor air depollution represents an interesting path for preventing indirect disease. In the present work, a simple and efficient PMs trapping media based on the use of an oil-coated structured polymer media was developed for passive trapping of various PMs, ranging from coarse (PM10), to fine (PM2.5) and ultra-fine (PM1) dimension in outdoor environment. The device can be easily regenerated by a simple washing with a mixture of water and detergent followed by a new oil coating cycle. The total PM loading mass of the passive trap and the recovered PMs are analyzed through different techniques and confirm the great efficiency of such filter to trap various PMs when exposed to a high traffic road. The spent filter can be regenerated through a simple washing step and can be repeatedly re-used with similar PM loading mass. The high and long-lasting total PM loading mass were also supported by numerical simulations based on computational fluid dynamics, also used to propose an optimization implementation of such system for future deployment at scale.

NOx Abatement by a TiO2-Based Coating under Real-Life Conditions and Laboratory-Scale Durability Assessment

In urban environments, various pollutants generated by road traffic, human, and industrial activities degrade outdoor and indoor air quality. Among these pollutants, nitrogen oxides (NOx) are subject to air quality regulations designed to protect human health and the environment. It is therefore crucial to keep their concentration as low as possible. Advanced oxidation processes are a practical choice for the degradation of NOx; among them, heterogeneous photocatalysis has proven to be a viable route. However, while the efficiency of this process has been widely demonstrated on a laboratory scale, it is still the subject of debate for real-life applications. The purpose of this study was to present a new field experiment on the application of a photocatalytic coating to outdoor walls. Air quality monitoring stations were used to evaluate the NOx concentration reduction instead of the chemiluminescent analyzer, in order to increase the number of sampling points. Statistical analysis was carried out to interpret the results. Density probability functions were plotted and showed a positive impact of the coating, leading to lower NOx concentrations. This work was completed by a laboratory-scale assessment of the coating’s durability using abrasion, QUV, and immersion/drying tests. The air depollution capacity of the chosen coating was significantly reduced after QUV testing.

Functional biocarbon-based coatings for wood protection and indoor air depollution

Growing concerns about indoor air pollution heighten the need to develop depolluting materials to achieve a healthy built environment. This study developed functional coatings for wooden surfaces using 20 wt% photocatalytic biocarbon particles doped with manganese oxide (BC–MnO2) and two different coating materials (linseed oil and waterborne acrylic). The samples' surface hydrophobicity and color properties were tested before and after accelerated aging. The depolluting potential of the samples was evaluated by formaldehyde removal efficiency test in indoor conditions. Results showed that adding BC-MnO2 particles increased the hydrophobicity regardless of the coating material's type. After accelerated aging, the hydrophobicity of all samples increased, which was attributed to the curing of the oil and acrylic polymers and the increase in surface roughness eventually caused by surface damage. The color change (ΔE) was more intense in the case of uncoated wood and samples without BC-MnO2. However, the BC-MnO2-containing coatings were effective in color preservation (ΔE < 2), which was attributed to the anti-UV property of biocarbon. The BC-MnO2-containing coatings exhibited a promising formaldehyde removal efficiency of up to 24 % and 46 % for oil and acrylic samples, respectively. The combination of BC-MnO2 and acrylic material was more favourable to attracting the formaldehyde molecules, likely due to the similar polarity. The developed functional coatings exhibited an acceptable ability for wood protection and formaldehyde remediation and can be potentially used to enhance indoor air quality.

Development of activated carbons derived from wastes: coffee grounds and olive stones as potential porous materials for air depollution

Agro-industrial byproducts and food waste necessitate an environmentally friendly way of reducing issues related to their disposal; it is also necessary to recover as much new raw material from these resources as possible, especially when we consider their potential usage as a precursor for preparing depolluting materials, such as activated carbon. In this work, coffee grounds and olive stones were chosen as precursors and the adsorption capacity of the obtained porous carbons for volatile organic compounds (VOCs) was studied. Microporous activated carbons (ACs) were prepared using chemical (K2CO3) and physical (CO2) activation. The influence of the activation process, type, and time of activation was also investigated. Measurements of VOCs adsorption were performed, and methyl–ethyl–ketone (MEK) and toluene were chosen as the model pollutants. The surface areas and total pore volumes of 1487 m2/g and 0.53 cm3/g and 870 m2/g and 0.22 cm3/g for coffee ground carbons and olive stone carbons, respectively, were obtained via chemical activation, whereas physical activation yielded values of 716 m2/g and 0.184 cm3/g and 778 cm2 g−1 and 0.205 cm3/g, respectively. As expected, carbons without activation (biochars) showed the smallest surface area, equal to 331 m2/g and 251 m2/g, and, hence, the lowest adsorption capacity. The highest adsorption capacity of MEK (3210 mg/g) and toluene (2618 mg/g) was recorded for chemically activated coffee grounds. Additionally, from the CO2 isotherms recorded at a low pressure (0.03 bar) and 0 °C, the maximum CO2 adsorption capacity was equal to 253 mg/g.

MnOx catalysts supported on SBA-15 and MCM-41 silicas for a competitive VOCs mixture oxidation: In-situ DRIFTS investigations

The catalytic oxidation of different volatile organic compounds (VOCs) has been widely studied for several decades within the field of air depollution. However, there is still much to understand regarding the effects that these VOCs have on each other when they are blended together in the reaction mixture, as would be expected in many emissions. Herein, the catalytic oxidation of toluene and 2-propanol on supported manganese oxides under both single and binary VOCs oxidation conditions has been studied. We have found the catalyst activity for VOCs mineralization and its selectivity towards other by-products (i.e., acetone or propylene from 2-propanol) to be strongly dependent on the reaction conditions, the catalyst redox properties and support acidity. We have also assessed the promotion/inhibition effects derived from the VOCs mixture and proposed the reaction mechanism in each case by means of in-situ DRIFTS measurements.

A Facile Approach of Fabricating Bifunctional Catalysts for Redox Applications by Uniformly Immobilized Metallic Nanoparticles on NiCr LDH

This study discloses the development of NiCr LDH, Ag@NiCr LDH, and Pd@NiCr LDH bifunction catalysts using a hydrothermal coprecipitation method followed by sol immobilization of metallic nanoparticles. The structures and morphologies of the synthesized nanocomposites were analyzed using FTIR, XRD, XPS, BET, FESEM-EDX, and HRTEM. The catalytic effectiveness of the samples was evaluated by tracking the progression of NaBH4-mediated nitrobenzene (NB) reduction to aniline and CO oxidation using UV-visible spectrophotometry and an infrared gas analyzer, respectively. Pd@NiCr LDH displayed much higher performance for both reactions than the bare NiCr LDH. The catalyst Pd@NiCr LDH showed robust catalytic activity in both the oxidation of carbon monoxide (T50% (136.1 °C) and T100% (200.2 °C)) and NaBH4-mediated nitrobenzene reduction (98.7% conversion and 0.365 min-1 rate constant). The results disclose that the Ni2+@ Cr3+/Cr6+ @Pd° ion pairs inside the LDH act as a charge transfer center and hence significantly enhance the catalytic performance. As a result, this research offers the novel NiCr LDH catalyst as a bifunctional catalyst for air depollution control and the organic transformation process.

Photocatalytic performance evaluation of flame‐sprayed and polymeric suspension coatings from TiO2 nanoparticles

AbstractBACKGROUNDHeterogeneous photocatalysis offers an interesting alternative to mitigate air pollution by using materials capable of reacting with toxic gases under ultraviolet light. One of these materials is titanium dioxide (TiO2), and thus it is necessary to analyze and improve its photocatalytic response for air depollution, in order to facilitate its use in surface applications.RESULTSThe photocatalytic ability of the synthesized TiO2 particles to remove nitric oxide (NO) was tested, and it was found that both the anatase and rutile phases present in the samples led to a NO abatement capacity of ≈60% η NO. Two different methods to coat surfaces with TiO2 particles were evaluated: thermal spray by oxyacetylene flame and dripping of polymeric suspensions of TiO2. A more detrimental effect on photocatalytic efficiencies was found using polymeric suspension rather than flame‐spraying as coating method. This was despite the anatase transformation to rutile and Ti7O13 that TiO2 particles undergo using the latter process as a consequence of heat transfer from the flame to the particles during the coating formation.CONCLUSIONResults obtained in this research demonstrate that polymeric suspensions inhibit the photocatalytic activity of TiO2 nanoparticles, probably due to the formation of a polymeric matrix on samples that constrains the action of pollutant and testing factors on samples. However, the thermal method can help retain part of the photocatalytic capability to abate NOx, despite depletion in the anatase content resulting from the heat transfer to the TiO2 raw particles sprayed to form coatings. © 2023 Society of Chemical Industry (SCI).

Study on functionalized acidic imidazolium‐based ionic liquids as effective adsorbents for HCHO storage

AbstractBACKGROUNDRecent works have shown how to develop methods with specific economic and environmental aspects; this is the main motivation for research on energy efficient processes and environmentally friendly materials for formaldehyde (HCHO) storage. One specific goal is to improve the adsorption capacity for HCHO by constructing closely contacted connections with absorbents.RESULTSIn this study, two ionic liquids (ILs), 1‐methylimidazole hydrogen sulfate [MIM][HSO4] and Imidazole hydrogen sulfate [IM][HSO4] as newly developed absorbents for HCHO storage are applied for the first time. Based on thermogravimetric analysis (TGA) and nuclear magnetic resonance (NMR) results, it is concluded that their exceptional capacity for storage of HCHO is 31.07 and 34.60 (g formaldehyde)⋅(mol ionic liquid)−1, respectively. In addition, to study the renewability of HCHO, the decomposition rates of the reaction products (as a function of decomposition time and decomposition temperature) were measured. The optimal kinetic model was selected to satisfy the formation and decomposition processes of the products. Thereafter, the activation energy (E), pre‐finger factor (A), decomposition rate constant of the decomposition reaction, and the rate constant of the reaction were determined. NMR results confirmed that the higher storage capacity of HCHO in [MIM][HSO4] and [IM][HSO4] is mostly attributed to the stronger covalent bonds between the ionic liquids (ILs) and HCHO.CONCLUSIONThese ILs are, thus, promising candidates as adsorbents for the design of air depollution processes. This study may provide new insights into the use of ILs for storage of HCHO for low‐cost, high‐performance, and environmentally benign adsorbents for indoor air purification. © 2022 Society of Chemical Industry (SCI).

Dye decomposition and air de-pollution performance of TiO2/SiO2 and N-TiO2/SiO2 photocatalysts coated on Portland cement mortar substates

In this study, the newly synthesized TiO2 and N doped TiO2 clusters were added to silica sol to synthesize N-TiO2/SiO2 composites via the sol–gel method. Afterwards, the prepared sols were applied by brushing on portland cement. Doping with nitrogen significantly increased the absorption of TiO2 towards the visible region, thus, increasing the photocatalytic activity. SEM characterization of the treated samples showed that the clusters were distributed in form of aggregates on the samples’ surface. The self-cleaning and air de-polluting performances were assessed through methylene blue degradation and the oxidation of nitrogen oxide, resulting in methylene blue (MB) removal of 85% and 78% after 60 min of irradiation for SN10TiO2 and STiO2, respectively. Regarding air de-pollution performance, the newly synthesized photocatalysts showed the ability of NOx reduction. However, their efficiency was somewhat lower, in which 23.81% of NO has been oxidized by the sample SN10TiO2, while SP25 showed a total NO conversion of 38.98%. The powdered xerogels of the newly synthesized nanoparticles revealed high photocatalytic efficiency concerning NO oxidation, resulting in a higher performance compared to those obtained by the xerogel containing P25.Graphical abstract

Development of green photocatalytic geopolymers for dye removal

The use of photocatalysts for water and air depollution processes that utilize light irradiation as an energy source is a well-known and popular research field. Geopolymers, as new sustainable three-dimensional porous inorganic polymers that have the potential to be tailored and used in different applications, are a novel promising candidate as adsorbent and catalyst for depollution applications. In this study, new green geopolymer photocatalysts were developed using rice husk, rice husk ash, metakaolin, ground granulated blast furnace slag, palm oil fuel ash, and TiO2. The depollution performance of the prepared TiO2-based geopolymers was evaluated using the methylene blue (MB) removal test; the geopolymers exhibited more than 95% efficiency in optimum conditions. Artificial neural network (ANN) was employed to predict the adsorption efficiency/capacity of MB adsorption on the developed geopolymer photocatalyst. The proposed ANN model performed well for the adsorption experimental dataset. MB adsorption on the geopolymer photocatalyst was optimized, and different kinetic theories were applied to the experimental data. The pseudo-second-order model explained the adsorption kinetics most effectively. With the high MB removal performance (higher than 95%) of the selected geopolymers, a new green and sustainable adsorbent could be introduced for wastewater depollution application.

Influence of organic acids on the phases and physical characteristics of titanium dioxide synthesized by sol–gel for air depollution through heterogeneous photocatalysis

AbstractBACKGROUNDAir pollution in big cities is becoming a global problem due to its negative consequences on human health and the ecosystem. Currently, some materials available promise successful gases pollutants removal, by reacting with them through photocatalysis when sunlight irradiates them. The most studied and applied material is TiO2; due to its chemical stability and availability, it is widely incorporated into cements, bricks, coatings, etc.RESULTSIn this study, powders of titanium dioxide were synthesized through the sol–gel method using tetraisopropoxide with and without organic acids. Their photocatalytic activity was determined by the colorimetric method, following the standard UNI‐11259, and by the NO abatement test using the international standard ISO‐22197‐1. The results of the colorimetric test indicate that all the samples are photoactive according to the criteria stablished in the standard. Additionally, a similar photocatalytic performance was evidenced in the NO abatement tests for all the samples despite the differences in their particle sizes and in their crystalline phase distributions obtained without and with the different organic acids used in the synthesis process.CONCLUSIONThe particles synthesized show that the use of organic acids influences the decrease in particle size; moreover, in the case of citric acid, a favourable effect on the appearance of the rutile phase is perceived.All the samples were photoactive and their photocatalytic performance, evaluated under a NO atmosphere, were not negatively affected by the largest particle size (150 nm) nor by the rutile phase content (42 wt.%). © 2022 Society of Chemical Industry (SCI).

Cu-TiO2/SiO2 photocatalysts for concrete-based building materials: Self-cleaning and air de-pollution performance

As a consequence of human activities, today, we are exposed to high pollution levels that cause building materials damage and many diseases. The application of TiO2 as coating on building materials has proven the efficiency of self-cleaning and air de-pollution. However, its performance is limited due to its absorption being exclusively located at UV light. In this study, Cu-TiO2 photocatalysts were integrated into silica sol–gel synthesis to manufacture new long-lasting term coatings with self-cleaning and air purification properties for concrete-based building materials. The enhancement of TiO2 photoactivity by incorporating Cu into its network has been clearly demonstrated. The self-cleaning and air de-polluting efficiency were assessed using methylene blue (MB), soot and NO, respectively, indicating that the presence of Cu promotes the TiO2 performance. For low doping levels, by increasing the copper loading, the TiO2 photoactivity increased. The highest efficiency was obtained by the photocatalyst containing 5% copper, which shows maximum destruction of methylene blue and soot of 95% and 50% within 60 min and 168 h of irradiation, respectively. However, higher copper loading led to a decrease in its performance, reaching a total degradation of MB and soot of 90% and 45% after 60 min and 168 h of irradiation, respectively, for the sample containing 15% of copper loading.

Synthesis of Zn/Cu metal ion modified natural palygorskite clay – TiO2 nanocomposites for the photocatalytic outdoor and indoor air purification

In this work, natural palygorskite clay was coupled with TiO2 (anatase) nanocrystals to obtain nanocomposites, in order to be tested as photocatalysts for outdoor and indoor air de-pollution. Three types of palygorskite, i.e., untreated (P) and metal treated, namely Zn-modified (Zn-P) and Cu-modified (Cu-P) palygorskite, were firstly synthesized. Afterward, these three kinds of samples were loaded with 70 wt% TiO2 nanoparticles, using hydrothermal treatment with titanium isopropoxide, abbreviated as P-TiO2, Zn-P-TiO2 and Cu-P-TiO2 nanocomposites, respectively. The nanostructure of all samples was gingerly characterized using a series of spectroscopic and microscopy techniques, including XRD, XPS, ATR-FTIR, TEM, BET and DRS. The photocatalytic performance of the nanocomposites to the decomposition of air pollutants was evaluated in the oxidation of NOx and acetaldehyde under both UV and visible light illumination, while a direct comparison to the corresponding photocatalytic performance of the reference TiO2 photocatalyst (P25) was also made. The results showed that the nanocomposites can be significantly more effective than P25 in the oxidation of NOx under UV light (∼3 times higher) and acetaldehyde under visible light (∼2 times higher). The recorded activities, as well as the lower TiO2 demand, make the palygorskite-based nanocomposites very promising catalysts for both outdoor (NOx) and indoor (acetaldehyde) air purification.

A parametric study of aerosol particle scavenging efficiency by spray droplets

Aerosol particle scavenging by droplets is commonly seen in workplaces as a process of air depollution, but it is used in an empirical way. Although many studies have been conducted on this process, there is still a lack of data concerning its efficiency in the field of occupational health. Thus, an experimental study is presented in this paper, where a mist is sprayed in counter-current to an ascending aerosol of alumina using commercial nozzles. The influence of various parameters on the spectral and total collection efficiency is studied. It is put in evidence that the collection of particles above the micron takes place mainly on the first tens of centimeters. Although an increase in the liquid flow rate and the positioning height lead to a better collection efficiency, the droplet diameter seems to be a predominant parameter to take into account. From the results, recommendations are thus proposed to optimize the aerosol collected by droplets. It is also shown that a simple impaction model can be used to predict the scavenging of aerosol particles, despite the strong assumptions.

Photocatalytic activity of TiO2-P25@n-TiO2@HAP composite films for air depollution.

We report on an elaboration of new composite photocatalysts (TiO2-P25@ n-TiO2@HAP) based on grafted size-selected 5-nm titanium-oxo-alkoxo nanoparticles on P25-TiO2 nanoparticles and HAP obtained by co-precipitation of salts. The 5-nm oxo-TiO2 particles were prepared in a sol-gel reactor with rapid reagents micromixing. The photocatalytic test of ethylene degradation, in a continuous-flow fixed-bed reactor, showed an increase of the photocatalytic yield for the composite photocatalysts with an addition of HAP. This result was interpreted by a synergy between adsorption and photo-oxidation.

Highly active composite TiO2-polypyrrole nanostructures for water and air depollution under visible light irradiation

Abstract Engineering photocatalytic materials for solar energy harvesting and environmental remediation is a very promising prospect to solve energy and environment issues. Here we report the preparation of a nanocomposite formed by TiO2 with nanostructured polypyrrole (PPyNS-TiO2) and its photocatalytic properties. We show that this nanocomposite is very active for water and air treatment under UV and visible light irradiation. This activity is higher than that of bare TiO2 and PPyNS, and much improved compared to that of TiO2-bulk polypyrrole (PPybulk-TiO2). The nanostructuration of the conjugated polymer is a key factor for the photocatalytic activity of the composite. The large enhancement of the photocatalytic activity is ascribed to the heterojunction between PPyNS and TiO2, which broadens the absorption of visible light and facilitates the charge carriers’ separation. These results foresee the composite PPyNS-TiO2 photocatalyst for water and air purification in environment remediation.

Evaluation of the photocatalytic performance of construction materials for urban air depollution

The photocatalytic degradation of trichloroethylene and nitric oxide (model volatile organochloride and inorganic compounds) by two commercial TiO2-based cementitious materials at the laboratory scale was studied. TiO2 P25 was selected as the benchmark photocatalyst. The materials were characterized by N2 adsorption–desorption, TGA, SEM–EDX, and XRD, and the hydrophobic/hydrophilic nature of the cement surface was determined through contact angle measurements. Preliminary photoactivity tests in which a glass plate was covered with photocatalytic material were performed. Moreover, the photocatalytic activities of asphalt plates (approximately 1 cm thick) covered with either of the photoactive cementitious materials were also evaluated. A notable improvement in the photocatalytic activity from the first to the second photocatalytic run was observed because sample conditioning with airflow and UV-A irradiation led to the elimination of species (carbonates) that were adsorbed at active TiO2 sites, ensuring stability under operating conditions. The cementitious samples completely photooxidized the organochloride compound but presented reduced photoefficiency for nitric oxide oxidation. The results obtained when the materials were deposited on glass and asphalt showed the crucial influences of the sample loading and the nature of the substrate on nitric oxide photooxidation. Using TiO2 P25 led to the complete conversion of nitric oxide but also to the formation of a large amount of nitrogen dioxide. On the other hand, one of the photoactive asphalts exhibited a nitric oxide conversion rate of 32%, which was lower than that achieved with pure TiO2-P25, but using this material did not lead to the release of nitrogen dioxide. When tested according to the ISO 22197-1:2007 standard, the selected photocatalytic asphalt removed 29% of the NO and 22% of the NOx under more demanding operating conditions.

Titanium valorization: From chemical milling baths to air depollution applications

Titanium metal is widely used in the aeronautical sector for its specific properties and corrosion resistance. The design of titanium workpieces is based on chemical milling: a fast, precise, low cost technique popular in the aerospace industry. Material is removed from selected areas of a part by immersing it in a strong chemical reagent. This process produces shallow cavities on plates and sheets or removes shallow layers of materials from large aircraft components to optimize the strength/weight ratio. However, it leads to large volumes of wasted acid baths, which are harmful to the environment and have to be sent to an approved waste facility. The objective of this paper is to highlight a cleaner production process based on the circular economy concept, i.e. reduce, reuse and recycle to limit environmental pollution and operating costs. Waste from chemical milling baths used in the design of titanium parts was recovered with the aim of synthesizing titanium dioxide and using it for air depollution applications. The waste consisted of hexafluorotitanate compounds. Various processing techniques to synthesize titanium dioxide from hexafluorotitanate compounds were tested and resulted in powders having different physicochemical characteristics. The synthesis parameters studied were the nature of the decomplexing agent, the dehydration temperature and the heating period. Photocatalytic coatings were then formulated on the basis of the synthesized powders. They were applied to a mortar surface to evaluate their efficiency to degrade nitric oxide under two UV lighting intensities, 5 and 20 W/m2. Depending on the synthesis process conditions, the concentration and crystal form of titanium dioxide particles varied, leading to more or less efficient photocatalytic coatings. The proportions of anatase and rutile phases in the synthesized powders were between 3 and 13%, and 5 and 30%, respectively. Concerning the particle size distribution, the variations observed were dependent on the D-values. D10% was quite similar for all powders. However, D50% and D90% differed by a factor of two for some powders, notably because of the presence of impurities or remaining decomplexing agent particles. NO degradation varied depending on the photocatalytic dispersions and could reach 7% under an irradiation of 20 W/m2. This article highlights the possible valorization of a massive industrial waste for specific applications provided that the conditions of processing techniques are optimized.

One-pot synthesis of Au/N-TiO2 photocatalysts for environmental applications: Enhancement of dyes and NOx photodegradation

Au/N-TiO2 photocatalysts with enhanced photoactivity thanks to nitrogen doping and gold nanoparticles (AuNPs) controlled deposition onto titania have been obtained by means of a simple and innovative one-pot synthesis promoting synergetic activity between these two approaches. The activity of the materials under study was evaluated by methylene blue and NOx degradation tests as models of environmental remediation processes for water purification and air depollution. The use of a deposition-precipitation method employing urea allows obtaining Au/N-TiO2 photocatalysts containing 0.3 at.% of nitrogen and 0.5 wt% of gold. The results obtained confirmed that the presence of both, nitrogen and AuNPs, enhanced the TiO2 photoactivity increasing the photodegradation of the dye and NOx in a factor of 4.5 and 1.7, respectively. In particular, the AuNPs enabled the photoactivity under visible light and improved substantially the selectivity of the NO degradation process. The photocatalysts here proposed maintain their properties as they are integrated into a silica matrix producing a product with potential use for the coating of different substrates, such as building materials for application in urban areas and fabrics or foams for the photocatalytic filters production.

In situ NO abatement by photocatalysis—study under continuous NO injection in a 10-m3 experimental chamber

Air pollution is a serious public health concern in France and many other countries. Nitrogen oxides (NOx) include nitrogen monoxide (NO) and nitrogen dioxide (NO2). They are mainly outdoor pollutants produced during combustion of fossil fuel. These gases can easily infiltrate buildings and thus increase indoor pollution. The recommended guideline values for NO2 are 200 μg/m3 (short-term exposure) and 40 μg/m3 (long-term exposure). Although no guideline values exist for NO, this gas can be oxidised by atmospheric ozone and thus produce NO2. This paper studies the depollution efficiency of photocatalysis towards indoor NO. Experiments were conducted at real scale, in a 10-m3 experimental chamber developed at the LMDC and used as a reactor. The interior walls of the chamber were equipped with painted plasterboards treated with photocatalytic coating (3 g/m2 of TiO2). Gas was continuously injected into the chamber according to a specific procedure: (1) pollutant injection at high flow rate to reach 200 ppb of NO, (2) pollutant injection at low flow rate in order to keep the NO concentration constant at 200 ± 10 ppb and (3) photocatalysis activation by switching on the light. Typical indoor lighting systems (fluorescent tubes, LED and halogen bulbs) were tested and UV fluorescent tubes were also used to optimise the photocatalytic efficiency. Results showed that NO indoor concentration was reduced by photocatalysis in real-world conditions. Significant NO degradation was obtained under visible light. In addition, using the experimental procedure presented in this paper, a new method for evaluating air depollution efficiency by photocatalysis at real scale is proposed.