Download or read book Gas Phase Photocatalytic Degradation on TiO2 Pellets of Volatile Chlorinated Organic Compounds from a Soil Vapor Extraction Well written by and published by . This book was released on 1993 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mineralization of trichloroethylene (TCE) and tetrachloroethylene (PCE) in gas stream from a soil vapor extraction (SVE) well was demonstrated with an annular photocatalytic reactor packed with porous TiO2 pellets in field trials at the Savannah River Site in Aiken, SC. The TiO2 pellets were prepared using a sol-gel method. The experiments were performed at 55 to 60°C using space times of 108 to 101° g s/mol for TCE and PCE. Chloroform (CHCl3) and carbon tetrachloride (CCl4) were detected as minor products from side reactions. On a molar basis, CCl4 and CHCl3 produced were about 2% and 0.2 % of the reactants.

Download or read book Photocatalytic Reaction Engineering written by Hugo de Lasa and published by Springer Science & Business Media. This book was released on 2006-10-31 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterogeneous photocatalysis is a novel technique for water purification. Publications on photocatalysis span a relatively recent period of not more than 25 years. This is a technique that, according to our extensive experience on the development of laboratory scale and pilot plant units, has great promise to eliminate water and air pollutants. Photocatalysis offers much more than competitive techniques where pollutants are transferred from phases; photocatalysis can achieve complete mineralization of pollutants leaving non-toxic species such as CO2 and H2O and can be exploited at close to room temperature and ambient pressure.

Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ceramic Ultrafiltration Membranes with Photocatalytic Properties written by Deborah Wildman Bell and published by . This book was released on 1999 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Photocatalytic Degradation of Chlorinated Volatile Organic Compounds in Gaseous Phase written by Nan-Min Wu and published by . This book was released on 1991 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advanced Oxidation Processes for Water and Wastewater Treatment written by Simon Parsons and published by IWA Publishing. This book was released on 2004-03-01 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: The suitability of Advanced Oxidation Processes (AOPs) for pollutant degradation was recognised in the early 1970s and much research and development work has been undertaken to commercialise some of these processes. AOPs have shown great potential in treating pollutants at both low and high concentrations and have found applications as diverse as ground water treatment, municipal wastewater sludge destruction and VOCs control. Advanced Oxidation Processes for Water and Wastewater Treatment is an overview of the advanced oxidation processes currently used or proposed for the remediation of water, wastewater, odours and sludge. The book contains two opening chapters which present introductions to advanced oxidation processes and a background to UV photolysis, seven chapters focusing on individual advanced oxidation processes and, finally, three chapters concentrating on selected applications of advanced oxidation processes. Advanced Oxidation Processes for Water and Wastewater Treatment will be invaluable to readers interested in water and wastewater treatment processes, including professionals and suppliers, as well as students and academics studying in this area. Dr Simon Parsons is a Senior Lecturer in Water Sciences at Cranfield University with ten years' experience of industrial and academic research and development.

Download or read book Photocatalytic Degradation of NOX VOCs and Chloramines by TiO2 Impregnated Surfaces written by Eva Miriam Land and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments were conducted to determine the photocatalytic degradation of three types of gas-phase compounds, NOX, VOCs, and chloramines, by TiO2 impregnated tiles. The oxides of nitrogen NO and NO2 (NOx) have a variety of negative impacts on human and environmental health ranging from serving as key precursors for the respiratory irritant ozone, to forming nitric acid, which is a primary component of acid rain. A flow tube reactor was designed for the experiments that allowed the UV illumination of the tiles under exposure to both NO and NO2 concentrations in simulated ambient air. The reactor was also used to assess NOx degradation for sampled ambient air. The PV values for NO and NO2 were 0.016 cm s-1 and 0.0015 cm s-1, respectively. For ambient experiments a decrease in ambient NOx of ~ 40% was observed over a period of roughly 5 days. The mean PV for NOx for ambient air was 0.016 cm s-1 and the maximum PV was .038 cm s-1. Overall, the results indicate that laboratory conditions generally simulate the efficiency of removing NOx by TiO2 impregnated tiles. Volatile organic compounds (VOC's) are formed in a variety of indoor environments, and can lead to respiratory problems (US EPA, 2010). The experiments determined the photocatalytic degradation of formaldehyde and methanol, two common VOCs, by TiO2 impregnated tiles. The same flow tube reactor used for the previous NOX experiments was used to test a standardized gas-phase concentration of formaldehyde and methanol. The extended UV illumination of the tiles resulted in a 50 % reduction in formaldehyde, and a 68% reduction in methanol. The deposition velocities (or the photocatalytic velocities, PV) were estimated for both VOC's. The PV for formaldehyde was 0.021 cm s-1, and the PV for methanol was 0.026 cm s-1. These PV values are slightly higher than the mean value determined for NO from the previous experiments which was 0.016 cm s-1. The results suggest that the TiO2 tiles could effectively reduce specific VOC levels in indoor environments. Chlorination is a widespread form of water disinfection. However, chlorine can produce unwanted disinfection byproducts when chlorine reacts with nitrogen containing compounds or other organics. The reaction of chlorine with ammonia produces one of three chloramines, (mono-, di-, and tri-chloramine). The production of chloramines compounds in indoor areas increases the likelihood of asthma in pool professionals, competitive swimmers, and children that frequently bath in indoor chlorinated swimming pools (Jacobs, 2007; Nemery, 2002; Zwiener, 2007). A modified flow tube reactor in conjunction with a standardized solution of monochloramine, NH2Cl, determined the photocatalytic reactions over the TiO2 tiles and seven concrete samples. The concrete samples included five different concrete types, and contained either 5 % or 15 % TiO2 by weight. The PV for the tiles was 0.045 cm s-1 for the tiles manufactured by TOTO Inc. The highest PV from the concrete samples was 0.054 cm s-1. Overall the commercial tiles were most efficient at reducing NH2Cl, compared to NOX and VOC compounds. However, the concrete samples had an even higher PV for NH2Cl than the tiles. The reason for this is unknown; however, distinct surface characteristics and a higher concentration of TiO2 in the concrete may have contributed to these findings.

Download or read book Gaseous Phase Photocatalytic Degradation of Volatile Organic Compounds by Titanium Dioxide written by Yuk-Lin Chan and published by . This book was released on 1999 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Insights Into the Mechanism of Photocatalytic Degradation of Volatile Organic Compounds on TiO2 by Using In situ DRIFTS written by Mu Gongsun and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Photocatalytic degradation is a cost-effective technology for the removal of volatile organic compounds. However, the mechanism of photocatalytic degradation of volatile organic compounds on TiO2 is still a challenging issue. Fortunately, infrared spectroscopy is a powerful technique, able to provide information about adsorption/desorption, intermediates/products, and interfacial reaction. The aim of this chapter is to review several aspects of our current understanding of the role of TiO2 in the degradation of volatile organic compounds, by using in situ diffuse reflectance infrared Fourier transform spectroscopy. We firstly review the state of photocatalytic degradation of volatile organic compounds briefly. This is followed by a summary of in situ infrared techniques. The interaction of TiO2 surfaces with vapor organic molecules and other species is then reviewed with the representative works in recent years. It ends with a brief future outlook on the mechanism of photocatalytic air purification of TiO2.

Download or read book Photocatalytic Oxidation of Gas phase BTEX contaminated Waste Streams written by and published by . This book was released on 1995 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 this work 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, we also 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.

Download or read book Photocatalytic Oxidation of Gas Phase Volatile Organic Compounds Using Undoped and Metal Ions Doped Titanium Dioxide Thin Films written by Noor Khaida Wati Mohd. Saiyudi and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Photocatalysts for Organics Degradation written by Barbara Bonelli and published by MDPI. This book was released on 2020-06-23 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: The quality of water is not only a technological and scientific issue, but a social and economic problem, in both developed and developing countries. Besides local regulations, which differ between regions and need constant upgrades, significant scientific developments are required in both the detection and removal of water contaminants. This Issue focuses on some recent advancements in the photocatalytic removal of organic pollutants, which is one of the aspects of the problem that involves the need of advanced catalysts and implies significant advancements in the field of materials science and chemical engineering.

Download or read book Gas phase photocatalytic oxidation of volatile organic compounds written by Anna Kachina and published by . This book was released on 2008 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Photocatalytic Degradation of Acetic Acid in Gas Phase in the Presence and in the Absence of O2 Using Different TiO2 and M TiO2 written by Ha Son Ngo and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the thesis is to better understand the mechanisms of photocatalytic degradation occurring under air or under nitrogen by studying the disappearance, mineralization and intermediate products of a simple molecule acetic acid. The reactions are carried out under these two atmospheres in gas phase and dynamic mode in order to place themselves under conditions of depollution or of energy generation. Firstly, we studied the degradation of acetic acid using the reference photocatalyst, TiO2 P25. Regardless of the atmosphere, air or N2, we have shown that the decarboxylation reaction is the first step in the disappearance of acetic acid. However, the fate of the methyl group depends on the carrier gas and the molar flow rate (in other words, the concentration of the pollutant in the gas phase). The mechanism of degradation occurring on the surface of the photocatalyst is then represented to explain the importance of this mechanism compared to that involving the hydroxyl radicals. The schematization of the mechanism includes the regeneration of the photocatalyst and the possible formation of H2O2, which has been observed in the literature. The study of the degradation products of acetic acid labelled with carbon 13 on the carbonyl group (CH313COOH) suggests that acetone and acetaldehyde do not result from the reduction of the carboxylic group. In a second step, the impact of photonic flux and moisture in the presence of TiO2 P25 as well as the effect of different commercial TiO2 on the conversion and more particularly the distribution of the intermediate products have been studied. Comparison of the effectiveness of different commercial TiO2s was discussed by considering the presence of rutile phase, the nature of the active species, the specific surface area of TiO2, the number of OH groups on the surface of the catalysts, the presence of impurities and the porosity of the materials.

Download or read book Photocatalytic Oxidation of Gas phase BTEX contaminated Waste Streams written by David A. Gratson and published by . This book was released on 1995 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Modification of Titanium Dioxide for Photocatalytic Degradation of Indoor Volatile Organic Compounds written by Zahra Shayegan and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The indoor air quality (IAQ) concern has risen since people spend most of their time (>90%) in indoor environments. Volatile organic compounds (VOCs) are categorized as a major group of gas pollutants. Indoor VOCs, known as hazardous compounds with several proven adverse health effects. Among various purification techniques, a heterogeneous photocatalytic oxidation process (PCO) is a promising technology for removing indoor VOC contaminants. Titanium dioxide (TiO2) is the leading candidate for PCO given its unique properties. However, no TiO2-based photocatalysts completely satisfy all practical requirements, considering the photoexcited charge carriers' short lifetime and a wide band gap requiring ultraviolet (UV) radiation. Moreover, the application of PCO for VOCs degradation is greatly hindered at high humidity levels. Herein, TiO2 modification techniques that include approaches for overcoming the inherent TiO2 limitations and improving the photocatalytic degradation of VOCs are studied. In this research, strategies for improving TiO2 photocatalyst activities by doping with different metal and/or non-metal ions as well as surface modification have been examined. Accordingly, the adsorption capacity and photocatalytic activity of P25 and surface fluorinated P25 coated on nickel foam were evaluated for VOCs removal. In addition, the photoactivity of visible-light-driven photocatalysts including; anatase/rutile carbon-doped P25, anatase/brookite cerium-doped TiO2, and anatase/brookite iron-doped TiO2 coated on nickel foam were evaluated for degradation of VOCs under both UV and visible light irradiation. Surface fluorination was then applied to reduce the surface hydrophilicity of Ce-TiO2 and Fe-TiO2 photocatalysts with the optimum Ce and Fe contents. Notably, their photocatalytic performance was investigated in continuous flow mode-of-operation reactors with small residence time, different relative humidity levels, and low-level inlet contaminant concentration. These techniques can improve PCO performance through the following mechanisms: i) by introducing an electron capturing level in the band gap that would generate some defects in the TiO2 lattice and help capture charge carriers and can also be excited under visible irradiation; ii) by slowing down the charge carrier recombination rate and increasing VOCs degradation; and iii) by reducing the surface hydrophilicity, which increases VOCs' adsorption capacity at high humid conditions.

Download or read book Gas Phase Adsorption and Photooxidation of Volatile Organic Compounds Over Titanium Dioxide written by Thomas Kevin Sontag and published by . This book was released on 1991 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: