Removal chlorinated solvents

In certain cases the organic dibasic acid is not sufficiently reactive for the purpose of polymerisation, and so it is replaced either with its anhydride or its acid chloride. For example polyamides (nylons) are often prepared by reaction of the acid chloride with the appropriate diamine. In the spectacular laboratory prepatation of nylon 6,6 this is done by interfacial polymerisation. Hexamethylenediamine is dissolved in water and adipyl chloride in a chlorinated solvent such as tetrachloromethane. The two liquids are added to the same beaker where they form two essentially immiscible layers. At the interface, however, there is limited miscibility and nylon 6,6 of good molar mass forms. It can then be continuously removed by pulling out the interface. 

The results of chain transfer studies with different polymer radicals are compared in Table XIV. Chain transfer constants with hydrocarbon solvents are consistently a little greater for methyl methacrylate radicals than for styrene radicals. The methyl methacrylate chain radical is far less effective in the removal of chlorine from chlorinated solvents, however. Vinyl acetate chains are much more susceptible to chain transfer than are either of the other two polymer radicals. As will appear later, the propagation constants kp for styrene, methyl methacrylate, and vinyl acetate are in the approximate ratio 1 2 20. It follows from the transfer constants with toluene, that the rate constants ktr,s for the removal of benzylic hydrogen by the respective chain radicals are in the ratio 1 3.5 6000. Chain transfer studies offer a convenient means for comparing radical reactivities, provided the absolute propagation constants also are known. 

Drews et al. [403] have focused on the use of SFE for quantitative analysis of fibre finishes as a replacement of current fibre analysis methods (Soxhlet) requiring chlorinated solvents to remove the finish from the fibre. It was observed that while the extraction... 

CSA [Catalytic solvent abatement] A process for removing chlorinated solvents from waste gases by catalytic oxidation. Two catalysts are used in series and the products are carbon dioxide, water, and hydrogen chloride. Developed in Germany by Hoechst and Degussa and licensed by Tebodin in The Netherlands. 

Several epidemiologic studies of scleroderma, undifferentiated connective tissue disease, and multiple sclerosis suggest modest associations with any solvents or with organic or chlorinated solvents Trichloroethylene, paint removers, and mineral spirits are some of the specific solvents implicated in these studies. Mechanistic research in MRL +/+ lupus mice. 

Thermally enhanced extraction is another experimental approach for DNAPL source removal. Commonly know as steam injection, this technique for the recovery of fluids from porous media is not new in that it has been used for enhanced oil recovery in the petroleum industry for decades, but its use in aquifer restoration goes back to the early 1980s. Steam injection heats the solid-phase porous media and causes displacement of the pore water below the water table. As a result of pore water displacement, DNAPL and aqueous-phase chlorinated solvent compounds are dissolved and volatilized. The heat front developed during steam injection is controlled by temperature gradients and heat capacity of the porous media. Pressure gradients and permeability play a less important role. 

A thin film of oil-like material was visible after 28 d on the exterior surfaces of the SPMD membrane. Analysis of this film indicated that the triolein impurities, oleic acid and methyl oleate, were the major constituents. This external lipid film (Petty et al., 1993) appeared to contain imbibed particulates. Although the film was removed from the SPMDs by solvent rinsing and analyzed separately, some lipid-mediated desorption of particle-associated PCBs and subsequent diffusion into the SPMD may have occurred prior to solvent-removal of the film. This observation suggests the potential for SPMD concentrations to reflect both vapor phase concentrations and to a lesser extent, lipid-extracted particulate-associated residues (see Section 3.9.2.). Unfortunately, concentrations of more chlorinated congeners in particulates collected on GFFs from the NIOSH method were often below quantitation limits, because only a small volume of air was sampled (1 m ) using this active method. 

Keefe Environmental Services Superfund Site, Epping, NH, 1993-1997 Chlorinated solvents TCE PCE benzene 1,1-DCE and 1,2-DCA 46 million gallons through May, 1997 52/gal of groundwater treated, 35,000/lb of contaminants removed D19692D... 

The CleanSoil process is an ex situ treatment technology that uses steam to remove hydrocarbons and chlorinated solvents from contaminated soils. The steam vaporizes the contaminants from the soil and carries them to a condenser for recovery. The water is converted back into steam and reused in the system. The remaining vapors pass through an activated carbon filter and are released into the atmosphere. The technology has been applied full-scale at multiple sites and is commercially available. 

The technology is best suited for the removal of water-soluble metals and organics. Organics that would most likely be mobilized by this process include aromatic compounds such as benzene, toluene, xylene, and phenolic compounds, as well as chlorinated solvents. Electroki-netic remediation is not a practical method of remediation for insoluble organics such as heavy hydrocarbons. 

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),... 

NEPCCO SoilPurge soil vapor extraction systems are noncontacting, oil-free, explosion-proof vacuum systems designed to remove volatile organic compounds (VOCs) from soil in situ. According to the vendor, benzene, toluene, ethylbenzene, and xylenes (BTEX), chlorinated solvents and other hydrocarbons can be treated with SoilPurge systems. The technology can also remove radon from soil. 

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