Download or read book A DOAS Study on the Oxidation Mechanism of Aromatic Hydrocarbons Under Simulated Atmospheric Conditions written by Rainer Volkamer and published by . This book was released on 2001 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A DOAS Study on the Oxidation Mechanism of Aromatic Hydrocarbons Under Simulated Atmospheric Conditions written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this work was to improve the understanding of the OH-radical initiated oxidation of aromatic hydrocarbons (benzene, toluene, p-xylene (BTX) and 1,3,5-trimethylbenzene (TMB)). These mechanisms are considered a major uncertainty in state-of-the-art photochemical models as they are used to predict photooxidant formation from urban air. Differential Optical Absorption Spectroscopy (DOAS) was employed in a systematic outdoor smog-chamber study at the European Photo Reactor (EUPHORE) located at the CEAM-Institute, Valencia/Spain. The available DOAS system was improved for this purpose. The yields of ring-retaining products (phenol from benzene, phenol-type and aldehyde-type compounds from p-xylene and TMB) and glyoxal (from BTX) were investigated. The phenol yield (Y(PHEN)= 53) was found more than two times higher than presently available literature values. Further, the bicycloalkyl-radical pathway was identified as a major pathway from BTX. It was demonstrated that the results of this study are representative for the atmosphere. Deviations from the the degradation pathways of BTX and TMB were further observed under conditions of high NOx (e.g. several ppm). The results of this work indicate that the representations of aromatics in photochemical models need to be updated. The results indicate that the contribution of aromatic hydrocarbons to the formation of photooxidants (i.e. ozone) is underestimated today.
Download or read book The Mechanisms of Atmospheric Oxidation of the Aromatic Hydrocarbons written by Jack G. Calvert and published by Oxford University Press. This book was released on 2002-02-14 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text reviews many of the aspects of the chemistry of the aromatic hydrocarbons and a consensus evaluation of the data by seven of the leading atmospheric scientists. The book covers topics ranging from the relative importance of the compounds in ozone and haze development to methods of estimating elemantary rate coefficients based on structural features of the compounds to mechanisms of aerosol generation and atmostpheric reaction of the polycyclic compounds to photochemical processes. It identifies features of the aromatic hydrocarbons requiring further study and appendicies give the structural formulas and nomenclature of the compounds reviewed in the book.
Download or read book Mechanistic Studies on the OH initiated Atmospheric Oxidation of Selected Aromatic Hydrocarbons written by Sascha Nehr and published by Forschungszentrum Jülich. This book was released on 2012 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Mechanisms of Atmospheric Oxidation of Aromatic Hydrocarbons written by Jack George Calvert and published by Oxford University Press on Demand. This book was released on 2002 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text reviews many of the aspects of the chemistry of the aromatic hydrocarbons and a consensus evaluation of the data by seven of the leading atmospheric scientists. The book covers topics ranging from the relative importance of the compounds in ozone and haze development to methods of estimating elemantary rate coefficients based on structural features of the compounds to mechanisms of aerosol generation and atmostpheric reaction of the polycyclic compounds to photochemical processes. It identifies features of the aromatic hydrocarbons requiring further study and appendicies give the structural formulas and nomenclature of the compounds reviewed in the book.
Download or read book Differential Optical Absorption Spectroscopy written by Ulrich Platt and published by Springer Science & Business Media. This book was released on 2008-05-30 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first part of this book reviews the basics of atmospheric chemistry, radiation transport, and optical spectroscopy before detailing the principles underlying DOAS. The second part describes the design and application of DOAS instruments as well as the evaluation and interpretation of spectra. The recent expansion of DOAS application to the imaging of trace gas distributions by ground, aircraft, and satellite-based instruments is also covered.
Download or read book Environmental Simulation Chambers Application to Atmospheric Chemical Processes written by Ian Barnes and published by Springer Science & Business Media. This book was released on 2006-01-13 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book gives in the first instance descriptions of different types of so-called environment chambers or photoreactors used mainly for the simulation and/or investigation of important chemical processes occurring in the atmosphere. The types of reactor described include outdoor and indoor chambers, temperature regulated chambers and glass and Teflon foil chambers The practical use of chambers is demonstrated in contributions by leading scientists in the field of atmospheric chemistry using, in many cases, current results. The types of atmospherically relevant investigations described include the measurement of reactivities, the measurement of radicals, the measurement of photolysis frequencies and products, kinetic and product studies on the oxidation of different types of hydrocarbons by important oxidant species (OH, N03, 03), formation of secondary organic aerosol from hydrocarbon oxidation etc. A special section includes contributions from eastern European countries which highlight some of the environmental research being performed in these countries. An abridged version of a specially commissioned review by the JRC Ispra on the status of environmental research in eastern European countries is also included in this section.
Download or read book The Gas Phase Oxidation of Hydrocarbons written by V. Ya. Shtern and published by Elsevier. This book was released on 2016-07-29 with total page 721 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Gas-Phase Oxidation of Hydrocarbons reviews research on the mechanism of oxidation of paraffins, naphthenes, olefines, and aromatic hydrocarbons and explains in detail the phenomena and theories with significant kinetic equations and graphs. This book first presents a study of the development of research on the gaseous-phase oxidation of hydrocarbons. The non-chain schemes for the oxidation of hydrocarbons, such as hydroxylation, peroxidation, and aldehyde and dehydrogenation schemes, are then discussed. This book also presents experimental investigations and important topics such as oxidation of methane and olefinic hydrocarbons. This selection will be invaluable to students and experts in the field of chemistry and related disciplines.
Download or read book Kinetic and Mechanistic Studies of the Hydroxyl Radical Initiated Photo oxidation of Saturated Hydrocarbons Under Simulated Atmospheric Conditions written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Photochemistry of Aromatic Hydrocarbons written by Inseon Suh and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Aromatic hydrocarbons constitute an important fraction (~20%) of total volatile organic compounds (VOCs) in the urban atmosphere. A better understanding of the aromatic oxidation and its association in urban and regional ozone and organic aerosol formation is essential to assess the urban air pollution. This dissertation consists of two parts: (1) theoretical investigation of the toluene oxidation initiated by OH radical using quantum chemical and kinetic calculations to understand the mechanism of O3 and SOA precursors and (2) experimental investigation of atmospheric new particle formation from aromatic acids. Density functional theory (DFT) and ab initio multiconfigurational calculations have been performed to investigate the OH-toluene reaction. The branching ratios of OH addition to ortho, para, meta, and ipso positions are predicted to be 0.52, 0.34, 0.11, and 0.03, respectively, significantly different from a recent theoretical study of the same reaction system. Aromatic peroxy radicals arising from initial OH and subsequent O2 additions to the toluene ring are shown to cyclize to form bicyclic radicals rather than undergoing reaction with NO under atmospheric conditions. Isomerization of bicyclic radicals to more stable epoxide radicals possesses significantly higher barriers and hence has slower rates than O2 addition to form bicyclic peroxy radicals. At each OH attachment site, only one isomeric pathway via the bicyclic peroxy radical is accessible to lead to ring cleavage. Decomposition of the bicyclic alkoxy radicals leads primarily to formation of glyoxal and methyl glyoxal along with other dicarbonyl compounds. Atmospheric aerosols often contain a considerable fraction of organic matter, but the role of organic compounds in new nanometer-sized particle formation is highly uncertain. Laboratory experiments show that nucleation of sulfuric acid is considerably enhanced in the presence of aromatic acids. Theoretical calculations identify the formation of an unusually stable aromatic acid-sulfuric acid complex, which likely leads to a reduced nucleation barrier. The results imply that the interaction between organic and sulfuric acids promotes efficient formation of organic and sulfate aerosols in the polluted atmosphere because of emissions from burning of fossil fuels, which strongly impact human health and global climate.
Download or read book Urban Air Pollution written by Ivo Allegrini and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the proceedings of a NATO Advanced Research Workshop which was also financially supported by the National Research Council of Italy. The Workshop was held from October 9 to 15, 1994, at the Centro Ettore Maiorana in Erice, Italy. Over 40 researchers from a wide variety of fields attended the Workshop, which brought to attention the ongoing research on various phenomena related to urban air pollution. The presence of high levels of atmospheric pollutants in the air of several urban centres of developed and developing countries causes a great concern among authorities and public opinion. Some 20% of the European population live in cities of more than 500,000 inhabitants and about 40% in cities of more than 50,000. Since exceedance of the Air Quality Guidelines has been observed to occur worldwide, a great effort has been addressed to the control of primary pollutants, but many problems related to secondary pollutants such as nitrogen containing species (nitrogen oxides, nitric and nitrous acid, ni trates) and photochemical oxidants (ozone, PAN and others) are far from being solved. The importance of atmospheric chemistry in understanding the processes occurring in urban atmospheres has been well recognised, thus there is a strong need to exchange experiences and results from urban centres in different Countries. Indeed, atmospheric pollution is very much dependent on the type of emissions which are very different according to the economic development of the urban centre under consideration.
Download or read book Atmospheric Oxidation of Selected Aromatic Hydrocarbons written by Romeo Iulian Olariu and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1989 with total page 1470 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Air Pollution written by Bhola R. Gurjar and published by CRC Press. This book was released on 2010-06-22 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: Air pollution is recognized as one of the leading contributors to the global environmental burden of disease, even in countries with relatively low concentrations of air pollution. Air Pollution: Health and Environmental Impacts examines the effect of this complex problem on human health and the environment in different settings around the world. I
Download or read book Proceedings of a Symposium on Preliminary Results from the September 1979 Researcher Pierce IXTOC I Cruise written by and published by . This book was released on 1980 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Organic Peroxy Radicals written by P. D. Lightfoot and published by . This book was released on 1992 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Aromatic Sextet written by Erich Clar and published by John Wiley & Sons. This book was released on 1972 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
