Polycyclic aromatic hydrocarbons PAHs results

One of the more significant classes of compounds resulting from and emitted by combustion sources include polycyclic aromatic hydrocarbons (PAHs) these species serve as nuclei for the formation of soot particles. Past studies have concluded that 85% of... 

Acridine is a three-ring nitrogen heterocycle, classified as polycyclic aromatic hydrocarbons (PAHs), some of which are proposed to be human carcinogens based on the evidence of carcinogenicity in experimental animals. Acridine is present in crude oil and tar pitch, as well as in emissions resulting from their combustion. 

However, these results are not sufficient to estimate quantitative dependence on a level of the particular pollutants in the environment. The second working hypothesis on the relationship between pollutants loading and morbidity dynamics in the whole area of North Eurasia has been considered. This hypothesis was estimated using a complicated statistical treatment (Box 3). The considered pollutants were fertilizers, heavy metals, pesticides, radionuclides, oil products, and polycyclic aromatic hydrocarbons, PAH. 

A key feature of our polyphenylene dendrimers is that they can be planarized and thus reduced in dimensionality by intramolecular dehydrogenation [29,35]. This results in large, fused polycyclic aromatic hydrocarbons (PAHs). PAHs serve as structurally distinct, two-dimensional subunits of graphite and show attractive properties such as high charge carrier mobility, liquid crystallinity, and a high thermal stability, which qualifies these materials as vectorial charge transport layers [81]. 

A combined effect of natural organic matter and surfactants on the apparent solubility of polycyclic aromatic hydrocarbons (PAHs) is reported in the paper of Cho et al. (2002). Kinetic studies were conducted to compare solubilization of hydro-phobic contaminants such as naphthalene, phenanthrene, and pyrene into distilled water and aqueous solutions containing natural organic matter (NOM) and sodium dodecyl sulfate (SDS) surfactant. The results obtained after 72hr equilibration are reproduced in Fig. 8.19. The apparent solubility of the three contaminants was higher in SDS and NOM solutions than the solubility of these compounds in distilled water. When a combined SDS-NOM aqueous solution was used, the apparent solubility of naphthalene, phenanthrene, and pyrene was lower than in the NOM-aqueous solution. 

In 1978, the emission of benzo(a)pyrene (BaP) from an aluminum plant In the vicinity of Sundsvall, Sweden, was estimated to be about four times the total amount emitted from all the motor vehicles In that country. As might be expected, the result of this estimate caused considerable concern, and a survey of the air quality In the Sundsvall area was made In 1980-81. The program monitored concentrations of polycyclic aromatic hydrocarbons (PAH) and fluoride In ambient air, with samples being collected once each week. Concentrations of fluoride and meteorological data were measured by the aluminum company laboratory, while PAH concentrations were determined by the Norwegian Institute for Air Research (NILU). 

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... 

As early as 1964, polycyclic aromatic hydrocarbons (PAHs) known to be carcinogenic, such as benzo[a]pyrcne, were detected in broiled meat (164). A number of papers have been published about PAHs found in smoked and thermally treated foods as a result of pyrolysis or incomplete combustion of organic matter (165 -169). Less information is available on the nitrogen analogs, the basic azaarenes polycyclic aromatic nitrogen-containing hydrocarbons (PANHs), but they have been shown to be present in association with PAHs in various samples that contain nitrogen, such as processed food (170-172). 

Kayal, S.I., Connell, D.W., 1989. Polycyclic aromatic hydrocarbons (PAH) in sediments of the Brisbane River (Australia) preliminary results. Water Sci. Technol. 21, 161-165. 

Often, many simultaneously occurring pollutants or contaminants determine an environmental problem. In industry, agriculture, and households, products are often mixtures of many compounds. The process of production and consumption is accompanied by emissions and consequently by contamination. One example is the use of toxaphene in the past, a very complex mixture of polychlorinated camphenes, as a pesticide. Technical toxaphene consists of more than 175 individual compounds. A second example is industrial and domestic emissions resulting from the combustion of fossil fuels. The emissions contain both a mixture of gases (SO2, NOx, CO2, etc.) and airborne particulate matter which itself contains a broad range of heavy metals and also polycyclic aromatic hydrocarbons (PAH). 

In contrast to the results of Bossmann et al., Lindsey and Tarr [31,32] observed equivalent rate constants for polycyclic aromatic hydrocarbon (PAH) degradation with Fenton systems as had been previously observed for PAH reaction with hydroxyl radicals as generated by pulse radiolysis techniques [33], Such kinetic agreement suggests, but does not confirm, equivalent mechanisms. PAHs, unlike 2,4-dimethylaniline, are not expected to directly coordinate iron in aqueous solutions. 

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