Perchloroethylene solvent

The removal of perchloroethylene solvents such as the very toxic trichloroethylene (TCE) from soil and water is a rather difficult problem [331]. A bench-scale study was conducted in TCE-contaminated sand columns. The following operation was tested. Foam obtained using the anionic surfactant Steol CS-330 was injected in a pulsed operation, after which artificial groundwater followed, and then foam again. The result was 75% of the initial TCE content. After the TCE-degrading bacterial strain ENV 435 had been added with the second pulse of foam, the result of the treatment was 95-99%. 

Dipropylene glycol Sodium xylenesulfonate solvent, DDT 1-Chloronaphthalene solvent, decaffeinating coffee Perchloroethylene solvent, defoliants n-Butyl mercaptan solvent, degreasers... 

The boiling point of perchloroethylene is quite high (121°C, 250°F). This allows CTW to be used as the primary coolant because the exit temperature of the CTW is around 95°F — allowing 155°F for a temperature difference to provide condensation of the perchloroethylene solvent. Certainly, CTW is the least expensive type of cooling for fulfilling this primary demand for cooling. 

Chlorinated Solvents. Originally, successive chlorination and dehydro-chlorination of acetylene was the route to trichloroethylene [79-01-6], C2HCI3, and perchloroethylene [127-18-4], C2C1. ... 

Halogenation and Hydrohalogenation. Halogens add to the triple bond of acetylene. FeCl catalyzes the addition of CI2 to acetylene to form 1,1,2,2-tetrachloroethane which is an intermediate in the production of the industrial solvents 1,2-dichloroethylene, trichloroethylene, and perchloroethylene (see Chlorocarbons and chlorohydrocarbons). Acetylene can be chlorinated to 1,2-dichloroethylene directiy using FeCl as a catalyst... 

Chlorination of various hydrocarbon feedstocks produces many usehil chlorinated solvents, intermediates, and chemical products. The chlorinated derivatives provide a primary method of upgrading the value of industrial chlorine. The principal chlorinated hydrocarbons produced industrially include chloromethane (methyl chloride), dichloromethane (methylene chloride), trichloromethane (chloroform), tetrachloromethane (carbon tetrachloride), chloroethene (vinyl chloride monomer, VCM), 1,1-dichloroethene (vinylidene chloride), 1,1,2-trichloroethene (trichloroethylene), 1,1,2,2-tetrachloroethene (perchloroethylene), mono- and dichloroben2enes, 1,1,1-trichloroethane (methyl chloroform), 1,1,2-trichloroethane, and 1,2-dichloroethane (ethylene dichloride [540-59-0], EDC). 

Tetrachloroethylene [127-18-4] perchloroethylene, CCl2=CCl2, is commonly referred to as "perc" and sold under a variety of trade names. It is the most stable of the chloriaated ethylenes and ethanes, having no flash poiat and requiring only minor amounts of stabilizers. These two properties combiaed with its excellent solvent properties account for its dominant use ia the dry-cleaning iadustry as well as its appHcation ia metal cleaning and vapor degreasiag. 

Dry Cleaning. In colorfastness to dry cleaning, ISO 105-D01 a specimen of the textile is placed in a cotton fabric bag together with stainless steel disks and agitated in perchloroethylene (30 min, 20°C) and the effect of the shade and the color of the solvent assessed using the grey scale. 

Perchloroethylene is a clear, dense, non-flammable volatile chlorinated solvent. It is widely used for dry cleaning small quantities are used in adhesives and cleaning agents. It is miscible with organic solvents but only slightly soluble in water. Relevant physical properties are given in Table 5.50. 

Dry cleaning - Several solvents exist to replace the ozone-depleting solvents that have traditionally been used by the dry cleaning industry. Perchloroethylene has been used for more than three decades. Petroleum solvents, while flammable, can be safely used when appropriate safety precautions are taken. They include white spirit, Stoddard solvent, hydrocarbon solvents, isoparaffins, and n-paraffin. A... 

Remediation activities at American Thermostat included the excavation and thermal treatment of over 13,000 cubic yards of soil and sediments contaminated primarily with perchloroethylene, trichloroethylene, and solvents. The soil was excavated and treated using a thermal treatment unit called the low-temperature enhanced volatilization facility (LTEVF). The performance test for the site s thermal unit had just been completed at the time of the inspection, so there was limited activity. 

Propylene oxide is purified by steam stripping and then distillation. Byproduct propylene dichloride may be purified for use as a solvent or as a feed to the perchloroethylene process. The main disadvantage of the chlorohydrination process is the waste disposal of CaCl2. Figure 8-3 is a flow diagram of a typical chlorohydrin process. 

Common gases such as oxides of carbon and nitrogen, hydrogen sulphide, and inert gases. Liquids which pose a health hazard due to volatilization, e.g. mercury and degreasing with chlorinated solvent, i.e. dry cleaning with perchloroethylene or metal cleaning with trichloroethylene. 

Aqueous scouring is expensive in terms of water use and effluent treatment and it can cause entanglement of delicate wool fibres. Solvent scouring offers an effective alternative but it is essential that the solvent does not enter the environment. Earlier solvent-based processes included the use of perchloroethylene in which 8-18% water had been emulsified with a surfactant. Current processes are based on hexane (de Smet process), 1,1,1-... 

Polyurethanes have also been used for many years. They can be applied from a solvent such as perchloroethylene, but such solvents are increasingly under environmental scrutiny. An aqueous polyurethane formulation is normally applied by padding, followed by baking at 150 °C using sodium carbonate as catalyst. 

Perchloroethylene (tetrachloroethylene) is a nonflammable solvent of low toxicity that dissolves and removes H blister and V nerve agents but does not neutralize them. NIOSH has recommended that this substance be treated as a potential human carcinogen. It does not work with G nerve agents. 

I now shall present a summary of an application of decision analysis to a specific chemical, perchloroethylene (PCE), a widely used dry cleaning solvent (also called tetrachloroethylene). Full details of this application are presented in an EPA report (5). Perchloroethylene was selected for us by the staff of the EPA Office of Toxic Substances as representative of chemicals on which EPA needed to make an unreasonable risk determination under TSCA. Our analysis was carried out as an exercise in methodology development and not to support any specific regulatory activities by EPA concerning perchloroethylene. 

Exposure Assessment. Since perchloroethylene is used as a dry cleaning solvent and PCE vapor is easily monitored, estimates of PCE exposure are relatively straightforward to make from existing data in the literature. Table II summarizes the results. Based on NIOSH data (17), machine operators are exposed to an average of about 30 ppm of PCE vapor during the working day, equivalent to a... 

In contrast to many other countries, chlorinated solvents and the vinyl chain are of minor importance. Carbon tetrachloride (CTC), perchloroethylene (PCE), vinyl chloride monomer (VCM) and ethylene dichloride (EDC) were manufactured for over 40 years by ICI Australia in Sydney, but the facilities were small by world standards and were progressively closed (CTC/PCE in 1991, VCM in 1996 and EDC in 1998) as they were no longer able to compete against imports from world-scale plants overseas. 

Solvent degreasing Vapors perchloroethylene, trichlorethylene, vapor decomposition (e.g., phosgene)... 

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