Hydrocarbon minerals, alkane

As discussed above, paint removers are mixtures of lipophilic and hydrophilic chemicals formulated together to ensure maximum attack on paint. Paint thinners are generally composed of varnish makers and painters (VM P) naphtha and mineral spirits. VM P naphtha is a mixture of aliphatic alkanes and alkenes and aromatic hydrocarbons. Mineral spirits is a higher molecular weight composition of similar compounds. 

One study demonstrated that parental occupational exposures to chlorinated hydrocarbons are associated with increased risks for leukemia, lymphoma, and urinary tract cancers in offspring. Another study showed associations between maternal exposures to solvents and increased incidences of leukemia. These solvents include 1,1,1-trichloroethane, toluene, and other mononuclear aromatic hydrocarbons, mineral spirits, and alkanes. Childhood brain cancers, the second leading cause of childhood cancer, have been associated with parental occupational exposures to toxic chemicals. Industries for which such associations have been found include 10 ... 

Alkane Content of Hydrocarbon Minerals and Other Sediments... 

Mineral Oil Hydraulic Fluids. Methods are available for analysis of the hydrocarbon components of mineral oil hydraulic fluids (predominantly straight and branched chain alkanes) in environmental samples. Some of these methods are summarized in Table 6-3. In general, water and sediment samples are extracted with a suitable solvent in a Soxhlet extractor (for solid samples) or in separatory funnel or shake flask (for liquid samples) (Bates et al. 1984 Peterman et al. 1980). The extract is cleaned up on silica gel or Florisil columns using a nonpolar solvent to elute the nonpolar alkanes. Analysis is usually performed by GC/MS (Bates et al. 1984 Kawamura and Kaplan 1983 Peterman et al. 1980). Method performance has not been reported, although 82% recovery of aliphatic hydrocarbons was reported for rainwater (Kawamura and Kaplan 1983). 

Hydrogen-deuterium exchange in alkanes shows the same dependence on the composition of solvent, and concentration of mineral acid, of platinum( 11) and of chloride ions as does the exchange in aromatic hydrocarbons. The dependence of the exchange rate on solvent composition has been discussed in Section III,B,1. The rate is independent of mineral acid concentration, increases nonlinearly with increase in the concentration of platinum 11), and decreases nonlinearly with increase in the concentration of chloride ions (55). The nonlinear dependences are due to the solvolysis of the PtCL,2- ion ... 

Solubility. Also involved in concentration of n-alkanes in the C27-C33 range may be the immobility of higher n-alkanes by reason of insolubility in mixed hydrocarbons underground. Immobility may be assisted by adsorptive forces involving minerals or such organic materials as kerogen. 

When solvent refined lignite (SRL) produced from North Dakota lignite was treated with liquid sulfur dioxide, the bulk of the coal liquid dissolved except for the saturated hydrocarbons and the mineral rich residue. The S02-solublc part did not contain any saturated hydrocarbons. The THF extract of the insolubles was mostly alkanes ranging from n-dodecane (C 2H26 to n tetra tetrancontane (C44Hgg). 

Eckart and co-workers have published a series of papers on laboratory studies of biodesulfurization of petroleum and petroleum fractions. The ability of various aerobic mixed cultures to desulfurize Romashkino crude oil (1.69 wt.% S) was addressed by Eckart et al. (21). After 5 days of incubation at 30°C in sulfur-free mineral medium with oil as sole source of carbon and sulfur, approximately 55% of the total sulfur was recovered in the aqueous phase from two of the most active cultures. In another study, gas oil (1.2 to 2 wt.% S), vacuum distillates (1.8 to 2 wt.% S) and fuel oil (up to 4 wt.% S) were used as sole carbon and sulfur sources for the oil-degrading microorganisms (36). The addition of an emulsifying agent was required to enhance desulfurization. Sulfur removals of up to 20% from the gas oil, 5% from the vacuum distillates, and 25% from the fuel oil were observed after 5 to 7 days of incubation. In a later study (37). approximately 30% of the sulfur was removed from fuel-D-oil by a mixed population of bacteria. The removal of benzothiophene, dibenzothiophene and naphthobenzothiophene was shown by high resolution MS analysis. Hydrocarbon degradation was observed in each of these studies. For example, in the latter study with fuel-D-oil, the decreases in the n-alkane and aromatic content were 59% and 14%, respectively. 

Scope of the Problem. Petroleum hydrocarbons are the principal components in a wide variety of commercial products (e.g., gasoline, fuel oils, lubricating oils, solvents, mineral spirits, mineral oils, and crude oil). Because of widespread use, disposal, and spills, environmental contamination is relatively common. It is important to understand that petroleum products are complex mixtures, typically containing hundreds of compounds. These include various amounts of aliphatic compounds (straight-chain, branched-chain, and cyclic alkanes and alkenes) and aromatic compounds (benzene and alkyl benzenes, naphthalenes, and PAHs). In addition, many petroleum products contain nonhydrocarbon additives such as alcohols, ethers, metals, and other chemicals that may affect the toxicity of the mixture. 

Purified mineral oils have been used medicinally and in foods. Subchronic toxicity studies of selected mixtures of mineral oil hydrocarbons (composed primarily of branched chain alkanes or cyclic alkanes) in F344 rats have identified the liver and the mesenteric lymph nodes as potential targets of toxicity for these mineral oils. The TPHCWG (1997c) derived chronic RfDs for low and high molecular weight mineral oils based on the hepatic effects (lipid granulomas) seen in these studies. 

Mineral oils are the by-products of the distillation of petroleum and are also called hydrocarbon oils and are obtained directly from petroleum refineries. The composition of these kinds of oil is predominately alkanes with trace amounts of aromatics and heterocyclics. They exhibit good lubricating properties and allow the attainment of low ultimate pressures. However, their chemical resistance is relatively poor, particularly to vigorous oxidants. As a result, mineral oils are very suitable for general-purpose use in vacuum pumps. 

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