Petroleum hydrocarbons, differentiation

The Microwave-Assisted Process (MAP ) technology uses microwaves, and solvents that are relatively transparent to microwaves, to extract chemicals from various matrices based on the temperature differential between the solvent and the target compound. According to the developers, the technology is applicable to soils and wastes containing polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), total petroleum hydrocarbons (TPH), and other organic compounds. 

Corapcioglu MY, Baehr A. 1985. Immiscible contaminant transport in soils and groundwater with an emphasis on petroleum hydrocarbons System of differential equations vs single cell model. Water Science and Technology 17 23-37. 

Interpretation of Hydrocarbon Analyses. Although obtaining accurate hydrocarbon measurements in samples is often a difficult task, it is equally as difficult to determine the sources of hydrocarbons from the data. The following criteria for differentiating petroleum hydrocarbons from biogenic hydrocarbons that have been suggested and applied over the past several years were outlined in (1) and are taken from there. 

Differentiation of Petroleum Hydrocarbons from Biogenic Hydrocarbons. Petroleum and biogenic hydrocarbons can be distinguished as follows, thus providing useful means for detecting petroleum. Note that not all differences apply to all organisms, nor to all crude oils and refined products. 

The results of Experiment 3 are shown in Table IV. This experiment compared the ability of different methods (III and V) to extract recently added petroleum hydrocarbons from marine sediment. The more vigorous extraction (Method V) increased the yield, but the additional material returned was unresolved. It appeared that the extractions were equally effective in returning the resolved hydrocarbons. In the unresolved portions of chromatograms, it was not possible to differentiate between recently added hydrocarbons and those from long-term inputs. This differentiation may be important for determining the extent of contamination from oil spills where extensive areas are impacted and control or prespill sediment samples (to determine background hydrocarbon levels) are not available. 

Petroleum resins are low molecular weight thermoplastic hydrocarbon resins synthesized from steam cracked petroleum distillates. These resins are differentiated from higher molecular weight polymers such as polyethylene and polypropylene, which are produced from essentially pure monomers. Petroleum resin feedstocks are composed of various reactive and nonreactive aliphatic and aromatic components. The resins are usually classified as C-5... 

Gas-Liquid Chromatography. In gas-liquid chromatography (GLC) the stationary phase is a liquid. GLC capillary columns are coated internally with a liquid (WCOT columns) stationary phase. As discussed above, in GC the interaction of the sample molecules with the mobile phase is very weak. Therefore, the primary means of creating differential adsorption is through the choice of the particular liquid stationary phase to be used. The basic principle is that analytes selectively interact with stationary phases of similar chemical nature. For example, a mixture of nonpolar components of the same chemical type, such as hydrocarbons in most petroleum fractions, often separates well on a column with a nonpolar stationary phase, while samples with polar or polarizable compounds often resolve well on the more polar and/or polarizable stationary phases. Reference 7 is a metabolomics example of capillary GC-MS. 

Mos of the solid carbonaceous material available to industry is derived from the pyrolysis of petroleum residues, coal, and coal tar residues. Understanding the reactions occurring during pyrolysis would be beneficial in conducting materials research on the manufacture of carbonaceous products. The pyrolysis of aromatic hydrocarbons has been reported to involve condensation and polymerization reactions that produce complex carbonaceous materials (I). Interest in the mechanism of pyrolysis of aromatic compounds is evidenced in a recent study by Edstrom and Lewis (2) on the differential thermal analysis of 84 model aromatic hydrocarbons. The study demonstrated that carbon formation was related to the molecular size of the compound and to energetic factors that could be estimated from ionization potentials. 

The relatively polar solvent, compared to, say, hexane, provides little separation of the hydrocarbon components of petroleum products, and therefore while they can be distinguished from the more polar oils investigated, insufficient information is obtained for differentiation between petroleum products. 

Overview. Because TPH is a broadly defined entity consisting of complex mixtures of hydrocarbons of varying chemical composition (due to differences in original petroleum products and differential, time-dependent, fate and transport of components within any particular TPH mixture), this section discusses available information for absorption, distribution, metabolism and excretion of components and petroleum products corresponding to the transport fractions of TPH. Limited... 

Differential thermal analysis has been applied to the degradation of hydrocarbon liquids (50-52) and has also been proposed for the quality control of grease (53, 54). Noel (55) showed that DSC could be used to characterize petroleum products and that the results could be correlated with some ASTM tests. The advantages of DSC over previous tests to characterize petroleum products are as follows ... 

Gussow, W. C. 1954. Differential trapping of hydrocarbons. Bulletin of the American Association of Petroleum Geologists, 38, 816-853. 

Segregation in the potential field of the adsorbent is, to some extent, similar to segregation in the gravitational field. Extensive calculations of gravitational segregation of hydrocarbon mixtures accounting for phase transitions were performed in connection with the problem of hydrocarbon distribution in petroleum reservoirs [105,106]. Two different approaches to such calculations can be identified. According to one approach, system (57) is differentiated with respect to x and transformed to a system of differential equations, which are solved by... 

The Saturated Aliphatic Hydrocarbons.—For the differentiation between the saturated aliphatic and aromatic hydrocarbons, the reactions typical of the benzene nucleus are applied. The paraffin hydrocarbons are inert towards many of the reagents to which the members of the aromatic series respond the most important reaction of the paraffins is substitution by halogens and this reaction is not suitable for qualitative application. The paraffin hydrocarbons usually met are the various fractions from petroleum and in dealing with these products special provision must be made for reaction due to the presence of not inconsiderable quantities of unsaturated products. 

---