Polychlorinated biphenyls, liquid

Until the 1970s the chemical used as the impregnating and dielectric medium for capacitor units was PCB (polychlorinated biphenyl) liquid. It was found to be toxic and unsafe for humans as well as contamination of the environment. For this reason, it is no longer used. The latest trend is to use a non-PCB, non-toxic, phenyl xylyl ethane (PXE-oil), which is a synthetic dielectric liquid of extremely low loss for insulation and impregnation of the capacitor elements or to use mixed polypropylene or allpolypropylene (PP) liquids as the dielectric. A non-oil dielectric, such as epoxy resin, is also used. 

Polychlorinated Biphenyl Liquid or Solid Very high Not pertinent 1.3-1.8... 

P.c.b.s PCBs PCB s Polychlorinated biphenyls, 9 Polychlorinated biphenyls, liquid, 9 Polychlorinated biphenyls, solid, 9 Polyhalogenated biphenyls, liquid, 9 Polyhalogenated biphenyls, solid, 9 Polyhalogenated terphenyls, liquid, 9 Polyhalogenated terphenyls, solid, 9... 

PCBs and PCTs are particularly troublesome liquids because of their toxicity and persistence in the environment. They are defined as polychlorinated biphenyls, polychlorinated terphenyls, monomethyl-dibromo-diphenyl metliane, monomethyl-dichloro-diphenyl metliane or monomethyl-tetrachlorodiphenyl methane. With low electrical conductivity and heat resistance they found wide use as dielectric fluids and were formerly used as hydraulic fluids. PCBs have not been made in the UK since 1977 and whilst most new uses for the substance are banned in most countries, around two-thirds of the 1.5 million tonnes manufactured in Europe and the US prior to 1985 still remain in equipment such as transformers. PCTs have been used in the past in a restricted range of specialist industrial applications. 

Extraction, employs a liquid solvent to remove certain compounds from another liquid using the preferential solubility of these solutes in the MSA. For instance, wash oils can be used to remove phenols mid polychlorinated biphenyls (PCBs) from die aqueous wastes of synthetic-fuel plants and chlorinated hydrocarbons from organic wastewater. 

SFE is used mainly for nonpolar compounds [e.g. polychlorinated biphenyls (PCBs)]. Typically, small aliquots of soil (0.5-10 g) are used for extraction. The extraction solvent is a supercritical fluid, most commonly carbon dioxide, which has properties of both a liquid and gas. The supercritical fluid easily penetrates the small pores of soil and dissolves a variety of nonpolar compounds. Supercritical carbon dioxide extracts compounds from environmental samples at elevated temperature (100-200 °C) and pressure (5000-10 000 psi). High-quality carbon dioxide is required to minimize... 

Chemicals degraded by WRF include pesticides such as organochlorines DDT and its very toxic metabolite DDE [8, 9] and organophosphate pesticides such as chlorpyrifos, fonofos and terbufos [10] polychlorinated biphenyls (PCBs) of different degrees of chlorine substitution [11-13], some even to mineralization [14, 15] diverse polycyclic aromatic hydrocarbons (PAHs) in liquid media and from contaminated soils or in complex mixtures such as creosote [16-18] components of munition wastes including TNT and its metabolites DNT [19-23], nitroglycerin [24] and RDX [25]. 

The van t Hoff equation also has been used to describe the temperature effect on Henry s law constant over a narrow range for volatile chlorinated organic chemicals (Ashworth et al. 1988) and chlorobenzenes, polychlorinated biphenyls, and polynuclear aromatic hydrocarbons (ten Hulscher et al. 1992, Alaee et al. 1996). Henry s law constant can be expressed as the ratio of vapor pressure to solubility, i.e., pic or plx for dilute solutions. Note that since H is expressed using a volumetric concentration, it is also affected by the effect of temperature on liquid density whereas kH using mole fraction is unaffected by liquid density (Tucker and Christian 1979), thus... 

In addition to the chemicals included on the other lists, the CDC also included heavy metals such as arsenic, lead, and mercury volatile solvents such as benzene, chloroform, and bromoform decomposition products such as dioxins and furans polychlorinated biphenyls (PCBs) flammable industrial gases and liquids such as gasoline and propane explosives and oxidizers and all persistent and nonpersistent pesticides. Agents included in this volume are limited to those that are most likely to pose an acute toxicity hazard. 

Solbakken, J.E., K. Ingebrigtsen, and K.H. Palmork. 1984. Comparative study on the fate of the polychlorinated biphenyl 2,4,5,2,4,5,-hexachlorobiphenyl and the polycyclic aromatic hydrocarbon phenanthrene in flounder (Platichthys flesus), determined by liquid scintillation counting and autoradiography. Mar. Biol. 83 239-246. 

Norstrom RJ, Won HT, Holdrinet MVH, et al. 1980a. Gas-liquid chromatographic determination of mirex and photomirex in the presence of polychlorinated biphenyls Interlaboratory study. J Assoc Off Anal Chem 63(1) 37-42. 

Polychlorinated biphenyls (PCBs) are colorless toxic organic substances that cause cancer and birth defects. There are more than 200 different types of PCBs, ranging in consistency from heavy, oily liquids to waxy solids, and each type further varying in the number and location of chlorine atoms attached to its molecular carbon rings. They are fire resistant and do not conduct heat or electricity well. Accordingly they have numerous commercial applications as insulation in electrical systems, for example, for transformers. 

Excerpt 4C is taken from an article in Analytical Chemistry. Headspace solid-phase microextraction (HSSPME) is coupled with GC to quantify polychlorinated biphenyls (RGBs) in milk. The RGBs are volatilized out of the liquid phase (milk) into the gas phase (headspace) and concentrated on an SPME fiber. The concentrated RGBs on the fiber are then injected into the GG. 

Pesticides (14, 85), polychlorinated biphenyls (86, 87) and herbicides (88) are usually separated by this technique also. In analytic work, however, the detection sensitivity of the selective detectors used in gas chromatography could not be achieved (59). Nevertheless, sUch substances can be separated by liquid chromatography with no attendant decomposition problems and no derivatization, making the procedure significantly simpler. i... 

Dual-phase extraction cannot remediate heavy chlorinated compounds, pesticides, or heavy hydrocarbons including polychlorinated biphenyls (RGBs), dioxin, fuel oil No. 6, or metals (with the possible exception of mercury). High-velocity pump systems (such as liquid ring vacuum pumps) tend to form emulsions, especially when diesel fuel is part of the recovered fluids. The problem of emulsion can be solved with prepump separation or a de-emulsification unit. 

CESAR was developed to address the problem of locating, characterizing, and removing dense non-aqueous-phase liquids (DNAPLs) from contaminated aquifer systems. The process is particularly suited to remediating groundwater contaminated with chlorinated solvents, such as trichloroethylene (TCE), tetrachloroethene (PCE), trichloroethane (TCE), and carbon tetrachloride (CCE). According to the vendor, CESAR can also be applied to sites contaminated with creosote, polychlorinated biphenyls (PCBs), Freon 113, volatile organic compounds (VOCs),... 

The vendor states that tetrachloroethane (PCE), trichloroethene (TCE), and other volatile compounds are difficult to remove from saturated soils because they are relatively insoluble. The vendor states that the technology is especially applicable to sites contaminated with dense non-aqueous-phase liquids (DNAPLs). Using the ISSZT technology creates an unsaturated zone from which these contaminants can be readily air stripped. Other contaminants such as polychlorinated biphenyls (PCBs) or metals can be isolated from groundwater and contained within barriers preventing the spread of contamination. 

Transportable incineration systems (TlSs) are rotary kiln incinerators used for the ex situ treatment of soils, sludges, sediments, liquids, and debris contaminated with heavy metals, polychlorinated biphenyls (PCBs), and other hazardous organic substances. 

The electric infrared incineration technology is a mobile thermal processing system that is suitable for soils or sediments contaminated with organic compounds, polychlorinated biphenyls (PCBs), and metals. Liquid organic wastes can be treated after mixing with sand or soil. Electrically powered silicon carbide rods heat organic wastes to combustion temperature while any remaining combustibles are incinerated in an afterburner. 

The Waste Management, Inc. (WMX), DeChlor/KGME process involves the ex situ dechlorination of liquid-phase halogenated compounds, particularly polychlorinated biphenyls (PCBs). KGME is the active species in a nucleophilic substitution reaction in which the chlorine atoms are replaced with fragments of the reagent. 

According to the vendor, ZEROS can treat hydrocarbons and chlorinated compounds such as polychlorinated biphenyls (PCBs) and dioxins. The vendor claims that the technology can treat contaminated soils, liquid wastes in metal and plastic containers, asbestos, medical and biomedical wastes, contaminated sludges, waste fuels, fuel residues, and municipal solid waste. The technology is commercially available. 

Permeation of Protective Garment Materials by Liquid Halogenated Ethanes and a Polychlorinated Biphenyl... 

Liquid-liquid extraction and sorbent accumulation are the most commonly employed isolation-concentration methodologies. In their ideal forms, these methods readily extract or accumulate relatively hydrophobic compounds such as polynuclear aromatic hydrocarbons (PAHs) or polychlorinated biphenyls. However, when HPLC is likely to be the method of choice, the compounds are likely to be highly polar or ionic. In these common cases, adaptation of the traditional methodology can readily serve to carry out the necessary isolation. 

DL Hayteas, DA Duffield. Use of high-performance liquid chromatography for the estimation of polychlorinated biphenyls and p,p -DDE residues in marine mammals. J Chromatogr B 705 362-366, 1998. 

A study to explore the effect of the sample matrix in SFE was done with a set of polychlorinated biphenyl (PCBs) and a river sediment matrix. Figure 12 shows the on-line SFE/GC characterization of a PCB standard ranging from monochloro to decachlorolbiphenyl compounds present at concentration levels from 5 to 100 microgram per milliliter. An election capture GC detector (ECD) was used for the determination of these PCB s. Since this PCB standard was made up in liquid... 

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