Polycyclic aromatic hydrocarbons fuels

Williams, P. T. Taylor, D. T. 1993. Aromatiza-tion of tyre pyrolysis oil to yield polycyclic aromatic hydrocarbons. Fuel, 72, 1469-1474. 

Unbumed Hydrocarbons Various unburned hydrocarbon species may be emitted from hydrocarbon flames. In general, there are two classes of unburned hydrocarbons (1) small molecules that are the intermediate products of combustion (for example, formaldehyde) and (2) larger molecules that are formed by pyro-synthesis in hot, fuel-rich zones within flames, e.g., benzene, toluene, xylene, and various polycyclic aromatic hydrocarbons (PAHs). Many of these species are listed as Hazardous Air Pollutants (HAPs) in Title III of the Clean Air Act Amendment of 1990 and are therefore of particular concern. In a well-adjusted combustion system, emission or HAPs is extremely low (typically, parts per trillion to parts per billion). However, emission of certain HAPs may be of concern in poorly designed or maladjusted systems. 

Major unknowns in the mechanism by which a hydrocarbon fuel bums concern the pyrosynthesis reactions that lead to the formation of polycyclic aromatic hydrocarbons (PAHs) and soot and the oxidation chemistry of atoms other than carbon and hydrogen (heteroatoms) in the fuel, particularly nitrogen, sulfur, and halogens. 

The synthesis of toxic organic compounds by humans, and their release into the natural environment began to assume significant proportions during the 20th century, especially after the Second World War. Prior to 1900, the chemical industry was relatively small, and the largest chemical impact of humans on the environment was probably dne to the release of hydrocarbons, especially polycyclic aromatic hydrocarbons (PAHs), with the combnstion of coal and other fuels. 

The recommended method of trichloroethylene disposal is incineration after mixing with a combustible fuel (Sittig 1985). Care should be taken to carry out combustion to completion in order to prevent the formation of phosgene (Sjoberg 1952). Other toxic byproducts of incomplete combustion include polycyclic aromatic hydrocarbons and perchloroaromatics (Blankenship et al. 1994 Mulholland et al. 1992). An acid scrubber also must be used to remove the haloacids produced. 

CRMs for Contaminants in Environmental Matrices For nearly two decades NIST has been involved in the development of SRMs for the determination of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and chlorinated pesticides in natural environmental matrices such as fossil fuels (Hertz et al.1980 Kline et al. 1985), air and diesel particulate material (May and Wise 1984 Wise et al. 2000), coal tar (Wise et al. 1988a), sediment (Schantz et al. 1990, 1995a Wise et al. 1995), mussel tissue (Wise et al. 1991 Schantz et al. 1997a), fish oil, and whale blubber (Schantz et al. 1995b). Several papers have reviewed and summarized the development of these environmental matrix SRMs (Wise et al. 1988b Wise 1993 Wise and Schantz 1997 Wise et al. 2000). Seventeen natural matrix SRMs for the determination of organic contaminants are currently available from NIST with certified and reference concentrations primarily for PAHs, PCBs, chlorinated pesticides, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofiirans (PCDFs) see Table 3.11. 

Hydrocarbon Microbiology biodegradation mechanisms of oil products (gasoline, kerosene, diesel, etc.), pyrolysis, polycyclic aromatic hydrocarbons, chlorinated solvents, and ether fuels refining processes (e.g., oil product microbial desulfurization) and oil production processes (e.g., bacterial corrosion). 

Human exposure to complex mixtures of polycyclic aromatic hydrocarbons (PAH) occurs through inhalation of tobacco smoke and polluted indoor or outdoor air, through ingestion of certain foods and polluted water, and by dermal contact with soots, tars, and oils CO. Methylated PAH are always components of these mixtures and in some cases, as in tobacco smoke and in emissions from certain fuel processes, their concentrations can be in the same range as some unsubstituted PAH. The estimated emission of methylated PAH from mobile sources in the U.S. in 1979 was approximately 1700 metric tons (2). The occurrence of methylated and unsubstituted PAH has been recently reviewed (1, 2). In addition to their environmental occurrence, methylated PAH are among the most important model compounds in experimental carcinogenesis. 7,12-Dimethylbenz[a]anthracene, one of... 

Yu, Y., T.L. Wade, J. Fang, S. McDonald, and J.M. Brooks. 1995. Gas chromatographic-mass spectrometric analysis of polycyclic aromatic hydrocarbon metabolites in Antarctic fish (Notothenia gibberifrons) injected with Diesel Fuel Arctic. Arch. Environ. Contam. Toxicol. 29 241-246. 

Polycyclic aromatic hydrocarbons (PAHs, sometimes also called polynuclear aromatics, PNA) are a hazardous class of widespread pollutants. The parent structures of the common PAHs are shown in Fig. 4 and the alkylated homologs are generally minor in combustion emissions. PAHs are produced by all natural combustion processes (e.g., wild fires) and from anthropogenic activity such as fossil fuels combustion, biomass burning, chemical manufacturing, petroleum refining, metallurgical processes, coal utilization, tar production, etc. [6,9,15,18, 20,24,131-139]. 

The composition consists of approximately 64% aliphatic hydrocarbons (straight-chain alkanes and cycloalkanes), 1 to 2% unsaturated hydrocarbons (alkenes), and 35% aromatic hydrocarbons (including alkylbenzenes and two- and three-ring aromatics). No 2 fuel oil contains less than 5% polycyclic aromatic hydrocarbons. 

PCDD/F and other chlorinated hydrocarbons observed as micropollutants in incineration plants are products of incomplete combustion like other products such as carbon monoxide, polycyclic aromatic hydrocarbons (PAH), and soot. The thermodynamically stable oxidation products of any organic material formed by more than 99% are carbon dioxide, water, and HCl. Traces of PCDD/F are formed in the combustion of any organic material in the presence of small amounts of inorganic and organic chlorine present in the fuel municipal waste contains about 0.8% of chlorine. PCDD/F formation has been called the inherent property of fire. Many investigations have shown that PCDD/Fs are not formed in the hot zones of flames of incinerators at about 1000°C, but in the postcombustion zone in a temperature range between 300 and 400°C. Fly ash particles play an important role in that they act as catalysts for the heterogeneous formation of PCDD/Fs on the surface of this matrix. Two different theories have been deduced from laboratory experiments for the formation pathways of PCCD/F ... 

Lee, L.S., Hagwall, M., Delfino, J.J., and Rao, S.C. Partitioning of polycyclic aromatic hydrocarbons from diesel fuel into... 

Westerholm, R. and Li, H. A multivariate statistical analysis of fuel-related polycyclic aromatic hydrocarbon emissions from heavy-duty vehicles, Environ. Sci. TechnoL, 28(5) 965-972, 1994. 

There is no medical test that shows if you have been exposed to fuel oils. There are methods to determine if your blood contains some fuel oil components such as benzene, toluene, and xylenes however, the concentrations of these compoimds in distilled fuels are so low that if they were detected in your blood, it might not indicate specific or exclusive exposure to fuel oils. For information on tests for measuring exposure to some individual components of fuel oils, see the ATSDR toxicological profiles on benzene, toluene, total xylenes, and polycyclic aromatic hydrocarbons. See Chapters 2 and 6 for information on symptoms that suggest exposure to fuel oils. 

The solubility of fuel oil no. 2, particularly the alkane and isoprenoid fractions, in seawater is increased by the presence of fulvic acid, although the solubilities of phenanthrene or anthracene, both polycyclic aromatic hydrocarbons, are unaffected by the presence of humic materials (Boehm and Quinn 1973). Unfiltered Narragansett Bay water was able to dissolve 1,560 g/L of fuel oil no. 2, although removal of... 

Lee L, Agwall M, Delfino J, et al. 1992. Partitioning of Polycyclic aromatic-hydrocarbons from diesel fuel into water. Environmental Science and Technology 26(11) 2104-2110. 

Before we examine the oxidation pathways available to aromatic systems, it is first instructive to review the most notorious role of these compounds in combustion chemistry their propensity to lead to soot formation. Soot is a byproduct of fuel-rich combustion, and soot particles can affect respiration and general health in humans." Soot production is a result of polycyclic aromatic hydrocarbon (PAH) formation in flames as reactive hydrocarbon radical intermediates combine to grow... 

HCZyme has been demonstrated in bench-scale tests and at field remediations to be effective on benzene, toluene, ethylene, and xylene (BTEX), Polycyclic aromatic hydrocarbons (PAHs), trichloroethylene (TCE), dichloroethylene (DCE), mineral spirits, fuel oils, motor oils, and hydraulic fluids. The vendor claims that HCZyme has been tested and used on over 2 million tons of petroleum-contaminated soils and is effective in breaking down petroleum hydrocarbons, polychlorinated biphenyls (PCBs), creosote, sludges, waste oils, free product, tank bottoms, and other chlorinated compounds (D18208L, p. 15). 

The PetroClean bioremediation system treats biodegradable contaminants (i.e., gasoline, diesel fuel, aviation fuel, solvents, polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), total petroleum hydrocarbons (TPH), and other organic compounds in soils and groundwater. 

The FEED technology effectively treats hydrocarbons (e.g., gasoline and fuel oils), non-halogenated aliphatic hydrocarbons, and polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, phenanthrene, and benzo(a)pyrene. 

Polycyclic aromatic hydrocarbons (PAH) are produced by the combustion, under fuel rich conditions, of almost any fuel. Although a few PAH with vinylic bridges (such as acenaphthylene) are lost, most PAH are quite stable in the atmosphere and eventually accumulate in environmental sinks such as marine sediments. Spatial and historical measurements of PAH in sediments Indicate that these compounds are stable, conservative markers of man s energy producing activities. 

Based on these and other measurements of PAH levels, we suggest the following scenario for the transport of PAH. The various fuels which are burned in metropolitan areas produce airborne particulate matter (soot and fly ash) on which polycyclic aromatic hydrocarbons are adsorbed. These particles are transported by the prevailing wind for distances which are a strong function of the particle s diameter. We suggest that the long range airborne transport of small particles accounts for PAH in deep ocean sediments. 

Although the ultimate source of much of particulate organic matter (POM) in the urban aerosol appears to be fossil fuel a specific knowledge of the amounts and classes of organic compounds contributed by various types of sources is lacking. Estimates of source contributions have been based on emission inventories which have been largely directed toward polycyclic aromatic hydrocarbons and/or benzo(a)pyrene. There has been very little work on the development of mathematical and statistical models for POM source identification and allocation (1). In view... 

Robbat, A., Jr., N. P. Corso, P. J. Doherty, and M. H. Wolf, Gas Chromatographic Chemiluminescent Detection and Evaluation of Predictive Models for Identifying Nitrated Polycyclic Aromatic Hydrocarbons in a Diesel Fuel Particulate Extract, Anal. Chem., 58, 2078-2084 (1986). 

Westerholm, R. N., T. A. Alsberg, A. B. Frommelin, and M. E. Strandell, Effect of Fuel Polycyclic Aromatic Hydrocarbon Content on the Emissions of Polycyclic Aromatic Hydrocarbons and Other Mutagenic Substances from a Gasoline-Fueled Automobile, Environ. Sci. Technol, 22, 925-930 (1988). 

In addition to the above criteria pollutants, one finds in the air a host of other gaseous and particulate pollutants, generally designated as hazardous air pollutants (HAPs), or simply air toxics. The US EPA identified 189 HAPs. Of course, not all HAPs are related to fossil fuel usage. Examples of fossil fuel HAPs are products of incomplete combustion (PIC), volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH), toxic metals (e.g., Hg, Pb, Cd,... 

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