Polynuclear aromatics, emissions

Finally it is likely that attention will be focused on emissions of polynuclear aromatics (PNA) in diesel fuels. Currently the analytical techniques for these materials in exhaust systems are not very accurate and will need appreciable improvement. In conventional diesel fuels, emissions of PNA thought to be carcinogenic do not exceed however, a few micrograms per km, that is a car will have to be driven for several years and cover at least 100,000 km to emit one gram of benzopyrene for example These already very low levels can be divided by four if deeply hydrotreated diesel fuels are used. 

The most commonplace substrates in energy-transfer analytical CL methods are aryl oxalates such as to(2,4,6-trichlorophenyl) oxalate (TCPO) and z s(2,4-dinitrophenyl) oxalate (DNPO), which are oxidized with hydrogen peroxide [7, 8], In this process, which is known as the peroxyoxalate-CL (PO-CL) reaction, the fluorophore analyte is a native or derivatized fluorescent organic substance such as a polynuclear aromatic hydrocarbon, dansylamino acid, carboxylic acid, phenothiazine, or catecholamines, for example. The mechanism of the reaction between aryl oxalates and hydrogen peroxide is believed to generate dioxetane-l,2-dione, which may itself decompose to yield an excited-state species. Its interaction with a suitable fluorophore results in energy transfer to the fluorophore, and the subsequent emission can be exploited to develop analytical CL-based determinations. 

Of particular interest in the application of cyclodextrins is the enhancement of luminescence from molecules when they are present in a cyclodextrin cavity. Polynuclear aromatic hydrocarbons show virtually no phosphorescence in solution. If, however, these compounds in solution are encapsulated with 1,2-dibromoethane (enhances intersystem crossing by increasing spin-orbit coupling external heavy atom effect) in the cavities of P-cyclodextrin and nitrogen gas passed, intense phosphorescence emission occurs at room temperature. Cyclodextrins form complexes with guest molecules, which fit into the cavity so that the microenvironment around the guest molecule is different from that in... 

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]. 

Leibman, C.P. Todd, P.J. Mamantov, G. Enhanced Positive Secondary Ion Emission From Substituted Polynuclear Aromatic Hydrocarbon/Sulfuric Acid Solutions. Org. Mass Spectrom. 1988, 25, 634-642. 

Sources. B[major component of polynuclear aromatic hydrocarbons, also known as polycyclic aromatic hydrocarbons, and is usually bound to small particulate matter present in urban air, industrial and natural combustion emissions, and cigarette smoke. 

Schuetzle, D., and J. M. Perez, Factors Influencing the Emissions of Nitrated-Polynuclear Aromatic Hydrocarbons (Nitro-PAH) from Diesel Engines, J. Air Pollut. Control Assoc., 33, 751-755 (1983). 

Gas Chromatography-Mass Spectrometric Characterization of Polynuclear Aromatic Hydrocarbons in Particulate Diesel Emissions... 

Sorrell and Reding [179] present an extension of this technique, for analysing l-3ng L 1 amounts of 15 polynuclear aromatic hydrocarbons in environmental water samples using high performance liquid chromatography, preceded by a clean-up using alumina, with ultraviolet monitoring and fluorescence emission-excitation spectra for identification. 

Polynuclear aromatic hydrocarbon (PNA) emissions were higher for EDS fuels in lab scale tests. These emissions appeared to be due to the pyrolysis of high molecular weight PNA into smaller ring structures. 

This paper covers the combustion performance of EDS fuel oil blends, with primary emphasis on the emissions of polynuclear aromatics (PNA). Previous testing of EDS fuel oil blends 0, 2) and other coal derived fuel oil blends (2) has shown that emissions of particulate and smoke are lower with coal-derived fuel oils than from the combustion of petroleum-derived fuel oils. 

Quantitative Determination of Polynuclear Aromatic Hydrocarbons in Fugitive Emissions From Coal Liquefaction Processes in Polynuclear Aromatic... 

The fluorescence detector is a specific and concentration-sensitive detector. It is based on the emission of photons by electronically excited molecules. Fluorescence is especially observed for analytes with large conjugated ring systems, e.g., polynuclear aromatic hydrocarbons and their derivatives. In order to extend its applicability range, pre-column or post-column derivatization strategies have been developed [9]. 

The production of coke by the carbonization of bituminous coal leads to the release of chemically complex emissions from coke ovens that include both gases and particulate matter of varying chemical composition. The chemical and physical properties of coke oven emissions vary depending on the constituents. The emissions include coal tar pitch volatiles (e.g., particulate polycyclic organic matter, polycyclic aromatic hydrocarbons, and polynuclear aromatic hydrocarbons), aromatic compounds (e.g., benzene and jS-naphthyl amine), trace metals (e.g., arsenic, beryllium, cadmium, chromium, lead, and nickel), and gases (e.g., nitric oxides and sulfur dioxide). 

Coke oven emissions are complex mixtures of hydrocarbons, including benzene and polynuclear aromatic compounds heavy metals including arsenic, beryllium, and cadmium and other particulates and vapors. In a study of coking workers in Taiwan, it was found that liver function profiles were altered by exposures to coke oven emissions and that exposure to even low levels of these emissions was hepatotoxic. The authors of the study suggest that the adverse hepatotoxic effects are caused by a mixture of chemicals rather than by any one identifiable speciesJ36 ... 

Eisenberg WC, Cunningham DLB. 1985. Analysis of polycyclic aromatic hydrocarbons in diesel emissions using high performance liquid chromatography A methods development study. In Cook M, Dennis AJ, eds. Polynuclear aromatic hydrocarbons Mechanisms, methods and metabolism. Columbus, OH Battelle Press, 379-393. 

Howard AG, Mills GA. 1983. Identification of polynuclear aromatic hydrocarbons in diesel particulate emissions. Int J Environ Anal Chem 14 43-54. 

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