Gas-phase Photocatalytic Oxidation of Organic Air Pollutants PDF Download
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Author: Svetlana Jõks
Publisher:
ISBN: 9789949232666
Category :
Languages : en
Pages : 78
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Book Description
Author: Svetlana Jõks
Publisher:
ISBN: 9789949232666
Category :
Languages : en
Pages : 78
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
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Book Description
Many small businesses are facing new regulations under the 1990 Amendments to the Clean Air Act. Regulators, as well as the businesses themselves, face new challenges to control small point-source air pollution emissions. An individual business-such as a dry cleaner, auto repair shop, bakery, coffee roaster, photo print shop, or chemical company-may be an insignificant source of air pollution, but collectively, the industry becomes a noticeable source. Often the businesses are not equipped to respond to new regulatory requirements because of limited resources, experience, and expertise. Also, existing control strategies may be inappropriate for these businesses, having been developed for major industries with high volumes, high pollutant concentrations, and substantial corporate resources. Gas-phase photocatalytic oxidation (PCO) is an option for eliminating low-concentration, low-flow-rate emissions of volatile organic compounds (VOCs) from small business point sources. The advantages PCO has over other treatment techniques are presented in this paper. This paper also describes how PCO can be applied to specific air pollution problems. We present our methodology for identifying pollution problems for which PCO is applicable and for reaching the technology's potential end users. PCO is compared to other gas-phase VOC control technologies.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Many small businesses are facing new regulations under the 1990 Amendments to the Clean Air Act. Regulators, as well as the businesses themselves, face new challenges to control small point-source air pollution emissions. An individual business-such as a dry cleaner, auto repair shop, bakery, coffee roaster, photo print shop, or chemical company-may be an insignificant source of air pollution,but collectively, the industry becomes a noticeable source. Often the businesses are not equipped to respond to new regulatory requirements because of limited resources, experience, and expertise. Also, existing control strategies may be inappropriate for these businesses, having been developed for major industries with high volumes, high pollutant concentrations, and substantial corporateresources. Gas-phase photocatalytic oxidation (PCO) is an option for eliminating low-concentration, low-flow-rate emissions of volatile organic compounds (VOCs) from small business point sources. The advantages PCO has over other treatment techniques are presented in this paper. This paper also describes how PCO can be applied to specific air pollution problems. We present our methodology foridentifying pollution problems for which PCO is applicable and for reaching the technology's potential end users. PCO is compared to other gas-phase VOC control technologies.
Author: Craig Steven Turchi
Publisher:
ISBN:
Category : Air
Languages : en
Pages : 6
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Book Description
Author: Anna Kachina
Publisher:
ISBN: 9789522145499
Category : Air
Languages : en
Pages : 85
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Book Description
Author: Mojtaba Malayeri
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The presence of volatile organic compounds (VOCs) in indoor air is inevitable. Their adverse effect on human health has encouraged researchers to develop various technologies for air pollution remediation. Photocatalytic oxidation (PCO) has been regarded as a promising and emerging technique for air purification and extensively investigated in the last two decades to characterize and improve the effectiveness and performance of this technology. In addition, the development of appropriate models can enhance the understanding of reactor performance and the evaluation of intrinsic kinetic parameters that enable the scale-up or re-design of more efficient large-scale photocatalytic reactors. This research works on mathematical modeling of gas phase photocatalytic reactors and analyses different key factors that can enhance pollutants decomposition. At the first step, a one-dimensional time-dependent mathematical model for continuous flow UV-PCO reactor has been developed. In this model, transfer of pollutants by advection and dispersion in bulk phase incorporates with the reaction rate based on the extended Langmuir Hinshelwood model in the catalyst phase. CFD modeling was also used to determine the flow distribution in the reactor at various airflow rates. Moreover, the light intensity distribution on the photocatalyst surface was simulated using the linear source spherical emission model. A dimensionless form of the model was then proposed to generalize the result for any scale. The proposed model was validated first by comparing with predictions of other models (inter-model comparison) and then by experimental data from two different scales (pilot and bench) of UV-PCO reactors. Furthermore, a sensitivity analysis using dimensionless parameters was conducted to find the controlling step in the PCO process. To validate the model, acetone, MEK, and toluene were tested in the UV-PCO reactor with a commercial PCO filter (TiO2 coated on silica fiber felts) at various operating conditions, such as concentration, relative humidity, irradiance and air velocity. The main issue for applying PCO technology in the indoor environment is the generation of hazardous by-products. The effect of by-products formation was usually ignored in former modeling studies. The next effort was to improve the model and build a comprehensive one to consider by-products generation in the UV-PCO reactor. To achieve this goal, a possible reaction pathway for degradation of each challenge compound was proposed based on identified by-products in analytical methods (GC-MS and HPLC). Different possible reaction rate scenarios were evaluated to find the best expression fitted to experimental data at the steady-state condition. The obtained reaction coefficients were then used to validate the model under various operating conditions. Finally, the Health Risk Index was used to investigate the implications of generated by-products on human health under varying operating conditions. The results indicated that the proposed model has a great potential to simulate the behavior of UV-PCO reactor in a real application.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Maurice K. Chemweno
Publisher:
ISBN:
Category : Catalyst poisoning
Languages : en
Pages : 158
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Book Description
Indoor air quality is one of the most promising applications of photocatalytic oxidation. Rapid deactivation of the photocatalyst by ubiquitous indoor air pollutants would diminish the utility of photocatalytic technology. We have studied deactivation of TiO 2 photocatalyst by oxidation of PolyDiMethylSiloxane (PDMS) and silicone sealant off-gas in a recirculating batch reactor. The oxidation of the Si-containing vapor was monitored with an FTIR equipped with a gas cell. Subsequent to each incremental exposure, a hexane oxidation reaction was performed to track the TiO 2 catalyst activity. In this manner, loss of catalyst activity was quantitatively related to oxidation of Si-containing organic molecules. The exposures were repeated until a substantial deactivation was achieved. Surface science techniques were used to view the topography of the catalyst and to identify the elements causing the deactivation.
Author: David A. Gratson
Publisher:
ISBN:
Category : Air
Languages : en
Pages : 0
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Book Description
Researchers at the National Renewable Energy Laboratory (NREL) have been exploring heterogeneous photocatalytic oxidation (PCO) as a remediation technology for air streams contaminated with benzene, toluene, ethyl-benzene, and xylenes (BTEX). This research is a continuation of work performed on chlorinated organics. The photocatalytic oxidation of BTEX has been studied in the aqueous phase,however, a study by Turchi et al. showed a more economical system would involve stripping organic contaminants from the aqueous phase and treating the resulting gas stream. Another recent study by Turchi et al. indicated that PCO is cost competitive with such remediation technologies as activated carbon adsorption and catalytic incineration for some types of contaminated air streams. In thiswork we have examined the photocatalytic oxidation of benzene using ozone (03) as an additional oxidant. We varied the residence time in the PCO reactor, the initial concentration of the organic pollutant, and the initial ozone concentration in a single-pass reactor. Because aromatic hydrocarbons represent only a small fraction of the total hydrocarbons present in gasoline and other fuels, wealso added octane to the reaction mixture to simulate the composition of air streams produced from soil-vapor-extraction or groundwater-stripping of sites contaminated with gasoline.
Author: M. Schiavello
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 218
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Book Description
Photocatalysis is a reaction which is accelerated by light while a heterogeneous reaction consists of two phases ( a solid and a liquid for example). Heterogeneous Photocatalysis is a fast developing science which to date has not been fully detailed in a monograph. This title discusses the basic principles of heterogeneous photocatalysis and describes the bulk and surface properties of semiconductors. Applications of various types of photoreactions are described and the problems related to the modeling and design of photoreactors are covered.
