Polycyclic aromatic hydrocarbons characteristics

Aitken MD, WT Stringfellow, RD Nagel, C Kazuga, S-H Chen (1998) Characteristics of phenanthrene-degrading bacteria isolated from soils contaminated with polycyclic aromatic hydrocarbons. Can J Microbiol 44 143-152. 

Due to its particular composition, biodiesel is biodegradable and allows reduced emissions, in terms of particulates and polycyclic aromatic hydrocarbons. Instead, the results of the combustion of biodiesel are contentious in relation to so-called NOx emissions, where it has been observed that such emissions are more or less increased, with respect to conventional diesel, depending on the characteristics of the engine in which it is used ... 

Chiou C, McGrody S, Kile D (1998) Partition characteristics of polycyclic aromatic hydrocarbons on soils and sediments. Environ Sci Technol 1998 264-269... 

Ogan, K. and Katz, E., Retention characteristics of several bonded-phase liquid-chromatography columns for some polycyclic aromatic hydrocarbons, J. Chromatogn, 188, 115, 1980. 

Kinetic characteristics are obtained for the reaction between several polycyclic aromatic hydrocarbons with nitrogen dioxide in dichloromethane at 25°C. They are in accord with the intermediate formation of the cation-radicals (Pryor et al 1984). 

The coordinated induction of the two degradative operons is not a universal characteristic of the system. In Rbodococcus sp. strain B4, isolated from a soil sample contaminated with polycyclic aromatic hydrocarbons, salicylate does not induce the genes of the naphthalene-degradative pathway (Grund et al., 1992). 

TNT forms charge-transfer, or 7r, complexes with polycyclic aromatic hydrocarbons, aromatic amines, and aromatic nitro compds a number of these are listed below in Table 2. The complexes with three amines (diphenylamine, diethyl-aniline, p-anisidine) have characteristic colors this forms the basis for a rapid and convenient thin-layer chromatographic analytical procedure (Ref 34) for the identification of very small amounts of TNT. (For a discussion of the many color reactions of TNT, and of composite expls containing it, see Vol 3, C405-L ff)... 

Niederer [100] used ion trap mass spectrometry and negative ion chemical ionisation to determine nitro- and oxypolyaromatic hydrocarbons in soils. Meyer et al. [101] have described a simple and reproducible method which provides the simultaneous determination of polycyclic aromatic hydrocarbons and het-eropolycyclic aromatic hydrocarbons (N, S, O) and their metabolites in contaminated soils. Contaminants extracted from the soil sample were separated by polarity and acid-base characteristics using solid-phase extraction on silica gel and a strong basic anion exchange material. A subfraction containing PANHs and neutral metabolites was subsequently fractionated into neutral and basic... 

Chiou, C.T., McGroddy, S. E., and Kile, D. E. (1999). Partitioning characteristics of polycyclic aromatic hydrocarbons on soil and sediments. Environ. Sci. Technol. 33, 2390-2394. 

Recently, Bonin and Simpson (2007) showed in their study that polycyclic aromatic hydrocarbons sorptive behavior could not be solely attributed to a specific SOM chemical characteristic (i.e., aliphaticity or aromaticity) and concluded that both structure and OM physical conformation are important in sorption processes. Martin-Neto et al. (1994b) used analysis of microwave power saturation curves (Weil et al., 1994) to obtain information about HA conformation. They observed that at pH > 3.5 a typical curve of homogeneous saturation was obtained for the oxisol HA, whereas at pH 2.3 inhomogeneous saturation occurred. The peat HA showed only homogeneous saturation. However, a similar inhomogeneous trend ... 

Humic substances (HS) are polymeric oxidation products that result from the decomposition of plant and animal residues. As a consequence of their colloidal state in natural waters, they play an important role in the transport of organic pollutants. Thus hydrophobic organic pollutants such as polycyclic aromatic hydrocarbons, DDT, and PCBs are known to bind well to humic substances, thereby enhancing the former s water solubility. One important characteristic of... 

An additional characteristic of white-rot fungal peroxidases is their wide-substrate specificity allowing them to oxidize substrates that shares structural characteristics with lignin units [38]. Among others, these enzymes are able to oxidize phenolic and nonphenolic pollutants [39], pesticides [40], polycyclic aromatic hydrocarbons [41] and industrial dyes [42]. These properties expand the range of applications also to the environmental sector. 

Supercritical fluid extraction (SFE) is a suitable process for many separation problems. The regeneration of the supercritical fluid is as important as the extraction step itself Therefore this paper presents a method to do this in a more isobaric way than the customary pressure reduction regeneration. For the example of soil remediation we have investigated the activated carbon regeneration of supercritical carbon dioxide loaded with the low-volatile polycyclic aromatic hydrocarbon (PAH) pyrene. Characteristics of supercritical fluid extraction for soil remediation are elevated temperatures and pressures up to 370 K and 300 bar. For this reason adsorption isotherms of pyrene on activated carbon up to these conditions are measured first. Subsequently this method is used to regenerate carbon dioxide in a closed solvent cycle plant with a 4 1 extractor. An economic analysis using these results indicate that the soil remediation costs will decrease for about 20 - 30 % by means of an activated carbon adsorber. 

Figure 11.5 shows that the functional group compositional analysis of the pyrolysis oil/waxes derived from the fixed-bed pyrolysis of PVC, PS and PET is very different from the polyalkene plastic pyrolysis oil/waxes. The spectra of the PVC pyrolysis oil/wax shows that the characteristic peaks of alkanes and alkenes are present as described for the polyalkene plastics. Since the PVC plastic polymer is based on a similar backbone structure to the polyalkene plastics, a similar degradation product oil/wax composition may be expected. However, the spectra for PVC in Figure 11.5 show that there are additional peaks in the region of 675-900 cm and 1575-1625 cm The presence of these peaks indicates the presence of mono-aromatic, polycyclic aromatic and substituted aromatic groups. Benzene has been identified as a major constituent in oils derived from the pyrolysis of PVC whilst other aromatic compounds identified included alkylated benzenes and naphthalene and other polycyclic aromatic hydrocarbons [19, 32, 39]... 

It is apparent from the above data that Thermofuel diesel produces significantly less particulates (smoke) at all engine loadings than conventional diesel. This is environmentally significant, as the particulates formed from diesel combustion contain polycyclic aromatic hydrocarbons (PAH) which have carcinogenic potential. The hotter burning characteristic of the Thermofuel relative to conventional diesel is likely to be responsible for the better burn-out of particulates [21]. 

The polycyclic aromatic hydrocarbons (PAHs) have been inferred to exist in the interstellar dust by the correlation of their general infrared spectral characteristics with observed celestial infrared emission bands [13-15]. 

Dias, J.R. (1987a). A Periodic Table for Polycyclic Aromatic Hydrocarbons. Part X. On the Characteristic Polynomial and Other Structural Invariants. J.Mol.Struct.(Theochem), 149, 213-241. 

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