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

Indoor air NO2 depollution by photocatalysis – comparing reactor and experimental chamber results

International Journal of Environmental Impacts: Management, Mitigation and Recovery

In spite of their positive role in the framework of circular economy, waste-to-energy processes are responsible for the emissions of a large number of air pollutants. Although this sector has made significant improvements in the air pollution control of primary emissions, the role of other sources (i.e. secondary emissions) has been often neglected. This paper aims at investigating the contributions of primary and secondary emissions expected from a waste gasification plant that is planned for the construction in an Alpine valley. The results from this analysis show that secondary emissions would play a significant role in the overall emissive footprint of the plant, contributing to 29% and 10%, respectively, of the overall emissions of dusts and total organic carbon. In the light of such results, secondary emissions would require an appropriate monitoring approach, which should complement the existing monitoring protocols for primary emissions.

Photocatalytic Purification of Air

Handbook of Research on Advancements in Environmental Engineering, 2015

The application of photocatalytic processes in environmental protection has a short history and is still in its beginnings. This issue, however, provokes continuous interest of the scientific and professional world. This chapter gives the overview of scientific and expert literature related to the application of heterogeneous photocatalysis in tackling the issues related to air protection. The focus is on purification of the indoor air, which comes to abatement of various volatile organic compounds. Basic principles of photocatalytic degradation of gaseous contaminants are presented, mostly on the TiO 2 photocatalyst, as well as a detailed account of the effect of various process variables on the rate of the photocatalytic reaction. The problem of TiO 2 deactivation is pointed out and deactivation mechanisms are described on the selected reaction system. The chapter aims to review technical aspects of heterogeneous catalysis applied in air protection and special attention is paid to different designs of photoreactors.

Photocatalytic air cleaners and materials technologies – Abilities and limitations

Building and Environment, 2015

Heterogeneous photocatalytic oxidation (PCO) is one of the most active research areas in environmental purification. Recently, research on PCO technologies-based air cleaners and building materials has been intensively conducted for indoor/outdoor air treatment. The innovative technology is dedicated to decompose gaseous pollutants using photocatalysts under illumination of UV or solar light without extra energy added. Comprehensive knowledge on the properties and performance of PCO for treatment of air using batch reactors or continuous reactors has been established. This critical review has been carried out with aims to examine the state-of-the-art of PCO technologies in the field of air purification and their application prospects. First, PCO fundamental principles, including mass transfer, adsorption, and surface reaction, are reviewed, providing rational explanations for research results. Second, the experimental work in various scales and other related research, such as modeling methods, coating techniques, and testing methods, are discussed and evaluated separately for PCO air cleaners and building materials. Based on these insights, the corresponding technological problems and future research directions for promotion of commercial applications in two aspects are also described in detail.

Photocatalytic air purifiers for indoor air: European standard and pilot room experiments

Environmental Science and Pollution Research, 2016

At the European level (CEN/TC386), some efforts are currently devoted to new standards for comparing the efficiency of commercial photocatalytic material/devices in various application fields. Concerning prototype or commercial indoor photocatalytic air purifiers designed for volatile organic compounds (VOC) abatement, the methodology is based on a laboratory airtight chamber. The photocatalytic function is demonstrated by the mineralization of a mixture of five VOCs. Experimental data were obtained for four selected commercial devices and three commercial materials: drop of VOC concentration, but also identification of secondary species (with special attention to formaldehyde), mineralization rates, and Clean Air Delivery Rate (CADR). With two efficient air purifiers, these laboratory experiments were compared to the results in two experimental rooms (35-40 m 3) where air pollution was introduced through wooden floor and furniture. The systems' ageing was also studied. The safety of the commercial products was also assessed by the determination of nanoparticle release. Standardized tests are useful to rank photocatalytic air purifiers and passive materials and to discard inefficient ones. A good correlation between the standard experiments and the experimental room experiments was found, even if in the latter case, the concentration of lower weight VOCs drops less quickly than that of heavier VOCs.

Photocatalytic oxidation technology for indoor environment air purification: The state-of-the-art

Applied Catalysis B: Environmental, 2017

Inevitable presence of volatile organic compounds (VOCs) in indoor environment and their adverse impact on human health and productivity have encouraged the development of various technologies for air pollution remediation. Among these technologies, photocatalytic oxidation (PCO) is regarded as one of the most promising methods and has been the focus of many research works in the last two decades. Titanium dioxide (TiO 2) is by far the most investigated photocatalyst for photocatalytic degradation of gaseous VOCs. This review article is intended to provide a comprehensive overview of the application of commercial TiO 2 photocatalysts for removal of VOCs in air. First, the fundamentals of photocatalytic oxidation are briefly discussed and common TiO 2-based photocatalysts are introduced. Then, the relations between the characteristics of photocatalysts (e.g. crystallinity, surface area and surface chemistry) and photocatalytic activity as well as the influence of key operating parameters on PCO processes are investigated. Afterwards, the reaction mechanisms and identified reaction intermediates/by-products for the most prevalent VOC families are reviewed. Finally, the paper discusses the deactivation of photocatalysts during PCO processes and some of the common regeneration techniques.

Photocatalytic NOx oxidation and storage under ambient conditions for air purification

2012

Ankara : The Department of Chemistry and the Graduate of Engineering and Science of Bilkent University, 2012.Thesis (Master's) -- Bilkent University, 2012.Includes bibliographical references leaves 113-123.Air pollution is one of the most serious environmental problems in both urban and rural settings with a direct impact on human health. A variety of chemical compounds can be associated with air pollution and gaseous nitrogen oxides (NOx), such as NO and NO2, are especially among the most hazardous environmental pollutants. NOx abatement can be efficiently performed at elevated temperatures (i.e. T > 300oC), however, an important challenge in air purification is the abatement of gaseous NOx species under ambient conditions (i.e. at room temperature and under regular atmospheric conditions). Photocatalytic systems offer promising opportunities in order to tackle this important environmental challenge, as these systems can be tailored to efficiently clean/purify air under ambi...

Photocatalysis for Air Treatment Processes: Current Technologies and Future Applications for the Removal of Organic Pollutants and Viruses

Catalysts, 2020

Photocatalysis for air treatment or photocatalytic oxidation (PCO) is a relatively new technology which requires titanium dioxide (TiO2) and a source of light (Visible or near-UV) to degrade pollutants contained in air streams. Present approaches for the photodegradation of indoor pollutants in air streams aim to eliminate volatile organic compounds (VOCs) and viruses, which are both toxic and harmful to human health. Photocatalysis for air treatment is an inexpensive and innovative green process. Additionally, it is a technology with a reduced environmental footprint when compared to other conventional air treatments which demand significant energy, require the disposal of used materials, and release CO2 and other greenhouse gases to the environment. This review discusses the most current and relevant information on photocatalysis for air treatment. This article also provides a critical review of (1) the most commonly used TiO2-based semiconductors, (2) the experimental syntheses a...

New Materials for Photocatalytic Purification of Air–A Review

Photocatalytic processes became to be used for water and air depollution. Titanium dioxide (TiO 2) as photocatalyst is activated by electromagnetic waves from UV-VIS range of spectrum and is used for degradation of some volatile organic compounds (VOCs) and nasty smells removal. The quality of air, equally indoor and/or outdoor is a serious environmental problem. Different methods are used for improving the air quality and photocatalysis as an advanced oxidizing process, could be a promising solution. Using different techniques, new materials were developed by scientists from many countries, proving a real interest for these new environmental friendly technologies. This study presents last developments regarding new photocatalytic materials which have to work not only in UV (like pure titanium dioxide) but also in Visible range of electromagnetic spectrum. Also these new photocatalysts have to be able to oxidize different types of organic and/or inorganic molecules and diminishing t...

Development of a sustainable photocatalytic process for air purification

Chemosphere, 2020

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