Polycyclic aromatic hydrocarbons PAHs solubility

Although these issues have already been briefly noted, they deserve a few additional comments. For freely water-soluble substrates that have low volatility, there are few difficulties in carrying out the appropriate experiments described above. There is, however, increasing interest in xenobiotics such as polycyclic aromatic hydrocarbons (PAHs) and highly chlorinated compounds including, for example, PCBs, which have only low water solubility. In addition, attention has been focused on volatile chlorinated aliphatic compounds such as the chloroethenes, dichloromethane, and carbon tetrachloride. All of these substrates present experimental difficulties of greater or lesser severity. 

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. 

Fig. 8.19 Solubility of polycyclic aromatic hydrocarbons (PAH) in sodium dodecyl sulfate (SDS, lOmg/L) and Sunwannee River natural organic matter (NOM, lOmg/L) solution. C denotes increased solubility in SDS and NOM solutions and is the solubility in water. (Cho et al. 2002)...

Polycyclic aromatic hydrocarbons (PAHs) have been extracted from contaminated land samples by supercritical fluid extraction jSFE) with both pure and modified carbon dioxide. Removing an analyte from a matrix using SFE requires knowledge about die solubility of the solute, the rate of transfer of the solute from the solid to the solvent phase, and interaction of the solvent phase with the matrix. These faclors collectively control the effectiveness of the SFF process, if not of the extraction process in general. The range of samples for which SFE has been applied continues to broaden. Applications have been in the environment, food, and polymers. 

The larger a polycyclic aromatic hydrocarbon (PAH) is, the less solubility the PAH will have due to the large and nonpolar planar molecular structure. 

Rao et al. (1990) investigated the effect of nonpolar cosolutes (trichloroethylene, toluene p-xylene), polar cosolutes (1-octanol, chlorobenzene, nitrobenzene, o-cresol) and polar cosolvents (methanol and dimethyl sulfoxide) on sorption of several polycyclic aromatic hydrocarbons (PAHs). The nonpolar cosolutes did not significantly influence PAH sorption, while the polar cosolutes (nitrobenzene, o-cresol), having sufficiently high aqueous solubilities, caused a significant decrease in PAH sorption. 

Maxim, C. R., and Kogel-Knabner, I. (1995). Partitioning of polycyclic aromatic hydrocarbons (PAH) to water-soluble soil organic matter. Eur. J. Soil Sci. 46,193-204. 

Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants (POPs) and widespread environmental contaminants, some of which may exhibit toxic, carcinogenic and mutagenic effects Because of their low water solubility and hydrophobic nature, PAHs are partitioned... 

Figure 2.6. Comparison of hydrophobicity and aqueous solubility for monoaromatic hydrocarbons (HCs) and polycyclic aromatic hydrocarbons (PAHs). (Data from Ref. 6 and 33.)...

Martin et al. [68] have modeled together solubility of 14 polycyclic aromatic hydrocarbons (PAHs) and fullerene in octanol and heptane utilizing descriptors calculated with the CODESS A package [69]. Also in this case, the applicability domain has not been validated. The structural difference between planar PAHs and spherical fullerene is probably too large for making reliable predictions. Moreover, the experimental solubilities of fullerene in both solvents (log S = —4.09 in heptane and log S>4.18 in octanol) are significantly lower than the solubilities of PAHs (—3.80[Pg.211]

The one class of substances which is virtually eliminated in all smoke flavourings is that of polycyclic aromatic hydrocarbons (PAH). While there are perhaps as many as ten of these identified as potential problems in smoked foods and smoke flavourings generated, the smoke flavouring industry has traditionally focused upon and tried to eliminate benzo[a]pyrene (b[a]p). Water solubility is the primary mechanism for precluding its occurrence in smoke flavourings generated with vaporous smoke. A... 

Smoke condensates are obtained by condensing smoke in water or another solvent. They may be further fractionated, purified or concentrated. The fractionation steps have two purposes to obtain products of interesting olfactory properties and to reduce the concentration of undesirable by-products from the smoke. Only the water-soluble fraction is used. The organic phase will be abandoned because a work up of the tar fraction is too expensive. The smoke solution will be filtered in order to remove polycyclic aromatic hydrocarbons (PAHs). According to a Russian patent [18] it is also possible to use 2% chitin and 0.5% chitosan for removing PAHs almost quantitatively. Afterwards the components of the smoke solution may be concentrated by distillation. The resulting product will be processed into smoke flavouring preparations. 

Polycyclic aromatic hydrocarbons (PAHs), in contrast, absorb light strongly in the solar UV region. Some of them, e.g., naphthalene, are much more photolabile in water than in organic solvents, although their solubility, of course, decreases dramatically as the number of rings increases. Mill et al. (1981) and Zepp and... 

Two different reactor configurations were studied in order to evaluate the removal of a highly soluble compound, the azo dye Orange II and a poorly soluble compound, the polycyclic aromatic hydrocarbon (PAH), anthracene. 

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