Toluene, PAHs

Unbumed Hydrocarbons Various unburned hydrocarbon species may be emitted from hydrocarbon flames. In general, there are two classes of unburned hydrocarbons (1) small molecules that are the intermediate products of combustion (for example, formaldehyde) and (2) larger molecules that are formed by pyro-synthesis in hot, fuel-rich zones within flames, e.g., benzene, toluene, xylene, and various polycyclic aromatic hydrocarbons (PAHs). Many of these species are listed as Hazardous Air Pollutants (HAPs) in Title III of the Clean Air Act Amendment of 1990 and are therefore of particular concern. In a well-adjusted combustion system, emission or HAPs is extremely low (typically, parts per trillion to parts per billion). However, emission of certain HAPs may be of concern in poorly designed or maladjusted systems. 

The degradation of BTEX both individually or in admixture has been shown in a lignindegrading white-rot fungus under nonlignolytic conditions, and was confirmed with ring-labeled toluene (Yadav and Reddy 1993). Interest in fungal transformation of PAHs is noted in the next part of this chapter, and illustrative examples of the hydroxylation of monocyclic arenes include the following (Smith and Rosazza 1983) ... 

The first step for the determination of PAHs is removal from the matrix by solvent extraction, which preferably is performed with boiling toluene or benzene (hot solvent extraction by refluxing see Jacob and Grimmer 1994), although other solvents (e.g. tol-uene/acetone, acetone, and dichloromethane) and other extraction procedures (ultrasonic treatment, Soxhlet extraction, and accelerated solvent extraction) can also be applied. 

Applications Mangani el al. [169] introduced forced-flow leaching for the direct extraction with hot toluene (at 100 °C) of low-MW PAHs from ashes. The method does not appear to have been used for poly-mer/additive analysis. 

Biopract provides technological products and processes for industry, agriculture, and environment. They not only produce technical enzyme preparations but also develop enzymes for applications in agriculture, food, and textile industry as well as in environmental technologies. On the later, bioremediation has been an area of service delivery from Biopract. Their activities regards microbial preparations for the bioremediation of organic contaminants (mineral oil (MKW), polycyclic aromatic hydrocarbons (PAH), benzene, toluene, ethylbenzene, xylene (BTEX), methyl-tert-butyl ether (MTBE), volatile organic hydrocarbons (VOC), and dimethyl sulfoxide (DMSO)). 

PAHs, benzene, toluene, hexachlorobenzene Halogenated hydrocarbons... 

The focus of the next four chapters (Chapters 14-17) is mainly on the theoretical/computational aspects. Chapter 14 by T. S. Sorensen and E. C. F. Yang examines the involvement of p-hydrido cation intermediates in the context of the industrially important heptane to toluene dehydrocyclization process. Chapter 15 by P. M. Esteves et al. is devoted to theoretical studies of carbonium ions. Chapter 16 by G. L. Borosky and K. K. Laali presents a computational study on aza-PAH carbocations as models for the oxidized metabolites of Aza-PAHs. Chapter 17 by S. C. Ammal and H. Yamataka examines the borderline Beckmann rearrangement-fragmentation mechanism and explores the influence of carbocation stability on the reaction mechanism. 

To determine the concentrations of benzene, toluene, ethylbenzene, and xylenes, approved methods (e.g., EPA SW-846 8021B, SW-846 8260) are not only recommended but are insisted upon for regulatory issues. Polynuclear aromatic hydrocarbons (PAHs) may be present in condensate, and evaluation of condensate contamination should include the use of other test methods (EPA SW-846 8270, SW-846 8310) provided that the detection limits are adequate to the task of soil and groundwater protection. Generally, at least one analysis may be required for the most contaminated sample location from each source area. Condensate releases in nonsensitive areas require analysis for naphthalene only. The analysts should ensure that the method has detection limits that are appropriate for risk determinations. 

Immunoassay methods correlate total petroleum hydrocarbons with the response of antibodies to specific petroleum constituents. Many methods measure only aromatics that have an affinity for the antibody, benzene-toluene-ethylbenzene-xylene, and PAH analysis (EPA 4030, Petroleum Hydrocarbons by Immunoassay). 

Test methods that analyze individual compounds (e.g., benzene-toluene-ethylbenzene-xylene mixtures and PAHs) are generally applied to detect the presence of an additive or to provide concentration data needed to estimate environmental and health risks that are associated with individual compounds. Common constituent measurement techniques include gas chromatography with second-column confirmation, gas chromatography with multiple selective detectors, and gas chromatography with mass spectrometry detection (GC/MS) (EPA 8240). 

The previous chapters have demonstrated that liquid-liquid extraction is a mass transfer unit operation involving two liquid phases, the raffinate and the extract phase, which have very small mutual solubihty. Let us assume that the raffinate phase is wastewater from a coke plant polluted with phenol. To separate the phenol from the water, there must be close contact with the extract phase, toluene in this case. Water and toluene are not mutually soluble, but toluene is a better solvent for phenol and can extract it from water. Thus, toluene and phenol together are the extract phase. If the solvent reacts with the extracted substance during the extraction, the whole process is called reactive extraction. The reaction is usually used to alter the properties of inorganic cations and anions so they can be extracted from an aqueous solution into the nonpolar organic phase. The mechanisms for these reactions involve ion pah-formation, solvation of an ionic compound, or formation of covalent metal-extractant complexes (see Chapters 3 and 4). Often formation of these new species is a slow process and, in many cases, it is not possible to use columns for this type of extraction mixer-settlers are used instead (Chapter 8). 

No studies on the transformation or degradation of fuel oils in the atmosphere were located. However, volatile components of fuel oils such as benzene, toluene, xylenes, and PAHs may be expected to enter the atmosphere where they are subjected to degradation processes. Further information on the atmospheric degradation of selected volatile hydrocarbons are presented in the ATSDR toxicological profiles for these chemicals (ATSDR 1989, 1990a, 1991a, 1991b). 

Physical and Chemical Properties. The physical and chemical properties of some fuel oils and their primary component chemicals, specifically kerosene and fuel oil no. 2, are well defined and can be used to estimate the fate of these fuel oils following release to the environment (Air Force 1989 lARC 1989). However, the physical and chemical properties of other fuel oils such as no. 1-D, no. 2-D, and no. 4, are not well defined, and data should be gathered in order to estimate the fate of these oils in the environment. Data needs associated with specific compounds that are components of fuel oils (e.g., benzene, toluene, xylene, and PAHs) are presented in the ATSDR toxicological profiles for these chemicals (ATSDR 1989, 1990a, 1991a, 1991b). 

Because fuel oils are composed of a mixture of hydrocarbons, there are few methods for the environmental analysis of fuel oils as a whole, but methods are reported for the analysis of their component hydrocarbons. The methods most commonly used to detect the major hydrocarbon components of fuel oils in environmental samples are GC/FID and GC/MS. See Table 6-2 for a summary of the analytical methods used to determine fuel oils in environmental samples. Several of the components of fuel oils have been discussed in detail in their individual toxicological profiles (e.g., benzene, toluene, total xylenes, and PAHs), which should be consulted for more information on analytical methods (ATSDR 1989, 1990a, 1991a, 1991b). 

According to the vendor, this technology is capable of removing chlorinated hydrocarbons, aliphatic hydrocarbons, aromatics, benzene, toluene, xylene, carbon tetrachloride, vinyl chloride, dichloromethane, and trichloroethane. Polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), and volatile inorganic solvents can also be removed. The technology is currently in use and is commercially available. 

At a former manufactured gas plant, 3 million gallons of wastewater contaminated with polycyclic aromatic hydrocarbons (PAHs) oil benzene, toluene, ethylbenzene, and xylenes (BTEX) and heavy metals were treated using an organoclay treatment train. The system consisted of an oil/water separator bag filters 9000 lb of organoclay and 6000 lb of GAC. Treatment costs were approximately 0.12/gal of treated water (D21556F, p. 12 D17268T, p. 29). 

HCZyme has been demonstrated in bench-scale tests and at field remediations to be effective on benzene, toluene, ethylene, and xylene (BTEX), Polycyclic aromatic hydrocarbons (PAHs), trichloroethylene (TCE), dichloroethylene (DCE), mineral spirits, fuel oils, motor oils, and hydraulic fluids. The vendor claims that HCZyme has been tested and used on over 2 million tons of petroleum-contaminated soils and is effective in breaking down petroleum hydrocarbons, polychlorinated biphenyls (PCBs), creosote, sludges, waste oils, free product, tank bottoms, and other chlorinated compounds (D18208L, p. 15). 

At the Sikes Disposal Pits Superfund site in Crosby, Texas, an HTTS unit was used to treat hazardous organic compounds including phenolic compounds, xylene, benzene, polynuclear aromatic hydrocarbons (PAHs), toluene, creosote, dichloroethane (DCA), vinyl chloride, and naphthalene (D184581, p. 216). The estimated treatment cost was 115 million including approximately 20 million in capital costs and 95 million in operation and maintenance costs. The estimated total cost for thermal treatment was 81 million. A total of 496,000 tons of soil and debris were incinerated. This corresponds to a total unit cost for incineration of 230 per ton and a unit cost of 160 per ton for thermal treatment (D184581, p. 227). 

According to the vendor, ECGO has been used to treat a wide range of organic compounds including benzene, toluene, ethylbenzene, and xylene (BTEX), chlorinated solvents, pesticides, total petroleum hydrocarbons (TPHs), phenols, polyaromatic hydrocarbons (PAH), and nitroamines. 

MARCOR Environmental, Inc. s, Advanced Chemical Treatment (ACT) is a chemical fixation method for the treatment of contaminated soils, sediments, and sludges. The vendor claims that by mixing contaminated materials with ACT reagents, the contaminants are oxidized, catalyzed, and mineralized. Target contaminants may include coal tar wastes polycyclic aromatic hydrocarbons (PAHs) benzene, toluene, ethylbenzene, and xylenes (BTEX) chromium copper and lead. 

ESTD, ex situ thermal desorption VOCs, volatile organic compounds TPH, total petroleum hydrocarbons BTEX, benzene, toluene, ethylbenzene, xylene PCBs, polychlorinated biphenyls PAHs, polycyclic aromatic hydrocarbons ISTD, in situ thermal desorption. 

According to the vendor. Microbial Fence has been used to treat groundwater contaminated with polycyclic aromatic hydrocarbons (PAHs) benzene, toluene, ethylbenzene, and xylenes (BTEX) and volatile organic hydrocarbons (VOCs) at petroleum, chemical, and wood treating facilities and manufactured gas plants. Microbial Fence was used alone or in conjunction with soil venting/bioventing, aquifer aeration, pump-and-treat methods, and/or recovery of non-aqueous-phase liquids (NAPLs). 

This technology has been used to treat polychlorinated biphenyls (PCBs), halogenated and nonhalogenated solvents, semivolatile organic compounds (SVOCs), polynuclear aromatic hydrocarbons (PAHs), pesticides, herbicides, fuel oils, benzene, toluene, ethylbenzene, and xylenes (BTEX), and mercury. This system has also treated Resource Conservation and Recovery Act (RCRA) hazardous wastes such as petroleum refinery wastes and multisource leachate treatment residues to meet RCRA Land Disposal Restrictions (LDR) treatment standards. 

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