Gases volatile organic compounds

Fine particulates Coarse particulates Sulfur oxides Reduced sulfur gases Volatile organic compounds Nitrogen oxides... 

Composition The height of TG steps determines the quantity, while the temperature of DTG peaks determines the quality. Direct coupling of a thermal analyzer to a mass spectrometer enables the identification of degradation products, such as water, inorganic gases, volatile organic compounds. 

Legislation has driven the development of these systems in order to decrease the emission of pollutants such as CO (a poisonous gas), volatile organic compounds (VOC) and NOx (implicated in smog formation) from vehicle exhausts [3]. 

Type of pollutant Weight % of volatile organic compounds contained In exhaust gas Relative risk factor... 

Liquid nitrogen is used in cold traps to remove and recover solvents or volatile organic compounds from gas streams to reduce atmospheric emissions. Liquid nitrogen can be used to accelerate the cooldown time for process reactors (29). 

Solvent Recovery. Most of the activated carbon used in gas-phase applications is employed to prevent the release of volatile organic compounds into the atmosphere. Much of this use has been in response to environmental regulations, but recovery and recycling of solvents from a range of industrial processes such as printing, coating, and extmsion of fibers also provides substantial economic benefits. 

Historically, measurements have classified ambient hydrocarbons in two classes methane (CH4) and all other nonmethane volatile organic compounds (NMVOCs). Analyzing hydrocarbons in the atmosphere involves a three-step process collection, separation, and quantification. Collection involves obtaining an aliquot of air, e.g., with an evacuated canister. The principal separation process is gas chromatography (GC), and the principal quantification technique is wdth a calibrated flame ionization detector (FID). Mass spectroscopy (MS) is used along with GC to identify individual hydrocarbon compounds. 

Fig. 3. A model integrated adsorption/electrothermal regeneration/cryogenic vapor recovery system for volatile organic compounds [91]. Reprinted from Gas Sep. Purif, Volume 10, Lordgooei, M., Carmichael, K. R., Kelly, T. W., Rood, M. J. and Larson, S. M., Activated carbon cloth adsorption cryogenic system to recover toxic volatile organic compounds, pp. 123-130, Copyright 1996, with permission from Elsevier Science.

Foster, K. L., Fuerman, R. G., Economy, J., Larson, S. M. and Rood, M. J., Adsorption characteristics of trace volatile organic compounds in gas streams onto activated carbon fibers, Chem. Mater., 1992, 4(5), 1068 1073. 

BS ISO 16200 Volatile organic compounds Solvent desorption and gas chromatography... 

Ozone (Oj) a gas similar to oxygen that is a criteria air pollutant and a major constituent of smog. See also reactive organic compounds volatile organic compounds. 

ATSDR. 1997. Volatile organic compounds in drinking water and adverse pregnancy outcomes. Interim report. United States Marine Corps Base Camp Lejeune, North Carolina, U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, Atlanta, GA. 

Ramsey JD, Flanagan RJ. 1982. Detection and identification of volatile organic compounds in blood by headspace gas chromatography as an aide to the diagnosis of solvent abuse. J Chromatogr 240 423-444. 

METHODS FOR PREPARING STANDARD MIXTURES OF VOLATILE ORGANIC COMPOUNDS IN A GAS... 

EPA SW-846 Method 8265, Volatile Organic Compounds in Water, Soil, Soil Gas, and Air by Direct Sampling Ion Trap Mass Spectrometry. Electronic version of EPA SW-846 Manual available at http //www.epa.gov/epaoswer/hazwaste/test/ new-meth.htm 8265. 

Photocatalytic oxidation can be an effective way of removing pollutants in the gas phase, such as NOx, SOx, and volatile organic compounds (VOCs). 

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