Polynuclear aromatic compounds, PNAs

Sims, R.C.C., Overcash, M.R. (1983) Fate of polynuclear aromatic compounds (PNA s) in soil plant systems. Residue Rev. 88. 

The technology can potentially treat the following contaminants halogenated volatiles and semivolatiles, nonhalogenated volatiles and semivolatiles (also listed as actual), organic pes-ticides/herbicides, polynuclear aromatic compounds (PNAs), solvents, and benzene-toluene-ethylbenzene-xylene (BTEX). 

EP(D)M is not classified as a hazardous material. It is not considered carcinogenic according to OSHA Hazard Communications Standard and lARC Monographs. Commonly used paraffinic extender oils contain less than 0.1 wt% polynuclear aromatic compounds PNAs. 

Outside of carbon monoxide for which the toxicity is already well-known, five types of organic chemical compounds capable of being emitted by vehicles will be the focus of our particular attention these are benzene, 1-3 butadiene, formaldehyde, acetaldehyde and polynuclear aromatic hydrocarbons, PNA, taken as a whole. Among the latter, two, like benzo [a] pyrene, are viewed as carcinogens. Benzene is considered here not as a motor fuel component emitted by evaporation, but because of its presence in exhaust gas (see Figure 5.25). 

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 emissions include coal tar pitch volatiles (e.g., particulate polycyclic organic matter [PPOM], polycyclic aromatic hydrocarbons [PAHs], and polynuclear aromatic hydrocarbons [PNAs]), aromatic compounds (e.g., benzene and p-naphthylamine), trace metals (e.g., arsenic, beryllium, cadmium, chromium, lead, and nickel), and gases (e.g., nitric oxides and sulfur dioxide). 

The petroleum oils are of three basic types aromatic, naphthemic, and paraffinic. Aromatic oils contain hazardous materials that require special handling precautions. Naphthenic oil does not contain hazardous levels of polynuclear aromatics (PNAs) and is less hysteretic. Because of these considerations the naphthenic oil is gaining in usage at the expense of more utilized aromatics. Paraffinic oil is only used modestly in tire compounds. The... 

Seventeen priority pollutant compounds can be classified as polynuclear aromatics (PNA). These compounds consist of two or more benzene rings that share a pair of carbon atoms. They are all derived from coal tar, with naphthalene being the largest constituent. Naphthalene derivatives such as alpha-naphthylamine and alpha-naphthol are used in some pesticide processes therefore, naphthalene is by far the most prevalent PNA priority pollutant in the industry. Acenaphthene, anthracene, fluorene, fluoranthene, and phenathrene are found as raw material impurities. Acenaphthene is found in one pesticide process as a raw material. The remaining ten PNAs are not suspected to be present in pesticide processes. 

In addition, hydrotreating converts polynuclear aromatic (PNA) compounds and other potential coke-forming material to more easily cracked naphthenes and paraffins. Like the removal of nitrogen compounds, the saturation of PNAs also requires more severe... 

The SS-SBR system can treat a wide range of contaminants, including nonhalogenated semivolatUe compounds, polynuclear aromatic (PNA) compounds, and benzene, toluene, ethylbenzene, and xylenes (BTEX). According to the vendor, the system has the advantage of control and reliability with readily adjustable soU/water ratios, nutrient amendments, and cosubstrate additions. 

Bioremediation using Biodrain is not possible for compounds resistant to biodegradation. Much longer degradation times are required for compounds such as polychlorinated biphenyls (PCBs) and polynuclear aromatics (PNAs) 3 to 7 years may be required for highly resistant contaminants. Bioremediation is also limited by below-freezing temperatures and free aqueous metals concentrations. Metals can be extracted or immobilized prior to biotreatment. Biodrain cannot be installed in rock or some landfill situations unless holes are drilled first. Current installation limits are approximately 40 ft. 

PNA (polynuclear aromatic) any of numerous complex hydrocarbon compounds consisting of three or more benzene rings in a compact molecular arrangement. Some types of PNA s are known to be carcinogenic (cancer causing). 

Aromatic compounds with two or more fused aromatic rings. Naphthalene is a polynuclear aromatic hydrocarbon (PAH or PNA). Indole is a polynuclear aromatic heterocycle, (p. 735)... 

Fillers are materials that modify rubber characteristics (e.g., hardness) and improve its physical characteristics (e.g., tensile strength), in addition to reducing costs. Rubber is sometimes compounded without the use of fillers the resultant product is called gum rubber. Typical fillers are calcined and hydrated clays, magnesium silicate (talc), magnesium oxide, and silicas. Carbon black, a common filler used to increase the heat resistance in industrial components such as tires, is not used as a filler in pharmaceutical components but it is used in smaller amounts as a black pigment. Polynuclear aromatic (PNA) hydrocarbons are a concern with carbon blacks but the grades used by manufacturers of pharmaceutical components contain very low concentrations. 

Sometimes referred to as PNAs (polynuclear aromatics), these are ubiquitous compounds found in many sites contaminated with petroleum or coal residues. They consist of two or more fused benzene rings. The PAHs of most interest in environmental chemistry are the 16 USEPA PAHs. These compounds were selected as representative, after analysis of numerous samples in the USA found that over 80% of the total PAH contribution could be attributed to these 16 priority compounds. The full list (with the number of rings in brackets) is as follows (see Fig. 6.11). 

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