Vapor pressure, chlorinated-hydrocarbons

Carbon disulfide is completely miscible with many hydrocarbons, alcohols, and chlorinated hydrocarbons (9,13). Phosphoms (14) and sulfur are very soluble in carbon disulfide. Sulfur reaches a maximum solubiUty of 63% S at the 60°C atmospheric boiling point of the solution (15). SolubiUty data for carbon disulfide in Hquid sulfur at a CS2 partial pressure of 101 kPa (1 atm) and a phase diagram for the sulfur—carbon disulfide system have been published (16). Vapor—Hquid equiHbrium and freezing point data ate available for several binary mixtures containing carbon disulfide (9). 

Volatile organic compounds (VOCs) include organic compounds with appreciable vapor pressure. They make up a major class of air pollutants.I his class includes not only pure hydrocarbons but also partially oxidized hydrocarbons (organic acids, aldehydes, ketones), as well as organics containing chlorine, sulfur, nitrogen, or other atoms in the molecule. 

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... 

Organophosphates (Fig. 10, Table 3) are more toxic than chlorinated hydrocarbons, in particular to humans,but they exhibit lower persistence in soils and do not seem to accumulate in soil fauna or concentrate in birds and fish [74]. This behavior is also related to an enhanced water solubility and lower vapor pressure of organophosphates. Malathion and Parathion (Fig. 10, Table 3) insecticides are known to be chemically hydrolyzed and biodegraded by micro-... 

UNIFAC Approach Jensen et al. [16] have employed the UNIFAC group contribution approach to develop an estimation method for pure-component vapor pressures. The model developed applies to hydrocarbons, alcohols, ketones, acids, and chloroalkanes of less than 500 molecular mass and in the vapor pressure region between 10 and 2000 mmHg. Burkhard et al. [8] extended this model to chlorinated aromatic compounds such as chlorobenzenes and PCBs. 

Richardson, L.T., Miller, D.M. (1960) Fungitoxicity of chlorinated hydrocarbon insecticides in relation to water solubility and vapor pressure. Can. J. Botany 38, 163-175. 

Doucette WJ, Andren AW (1988b), Chemosphere 17 345-359.. .Estimation of octanol/water partition coeffficients evaluation of six methods for highly hydrophobic aromatic hydrocarbons" Eitzer BD, Hites RA (1988), Environ. Sci. Technol. 22 1362-1364. Vapor pressures of chlorinated dioxins and dibenzofurans"... 

The discovery of chlorinated hydrocarbons in remote global environments prompted researchers to re-examine the rates of evaporation of these compounds. These compounds, usually of high-molecular-weight and low vapor pressure, exhibit unexpectedly high evaporation rates due to their high equilibrium vapor partial pressures (1,2). 

Chlorine Chlorine gas produced in the various electrochemical processes is saturated with water vapor at high temperatures and may also contain brine mist and traces of chlorinated hydrocarbons (originating from piping and rubber-lined vessels), and is normally at atmospheric pressure. Before the chlorine can be used it must (in this order) be cooled, purified, dried, compressed, and if necessary liquefied. 

The quantification of 1,1,1-trichloroethane in blood and urine samples can be achieved by the initial use of purge and trap methodology (Antoine et al. 1986 Barkley et al. 1980). This technique involves the liberation of the volatile chlorinated hydrocarbon by bubbling an inert gas through the sample matrices at elevated temperatures ( 50-95 °C). Higher temperature increases the vapor pressure of the compound, and the bubbling action serves, essentially, to increase the gas-liquid partition, and thus volatilize the compound of interest. The gaseous sample is collected on an adsorption tube, which frequently uses a polymeric sorbent such as Tenax GC. 

Volatilization and vapor phase transport are important processes in the dissipation of even the so-called nonvolatile pesticides, such as the chlorinated hydrocarbons. The vapor pressure or the vapor saturation density is therefore an important parameter to assess the persistence of the pesticide. Much work was done very early in the era of the (persistent) pesticides. Table 8.3 shows the vapor pressure and water solubility of some important chlorinated pesticides and contaminants in pesticide formulations. 

The highly persistent chlorinated hydrocarbons may also slowly disappear from soil through evaporation. Spencer and Cliath (1972) found that the vapor densities of DDT and DDE were approximately 21 times greater at 7.5% moisture content in soil than at 2.2% moisture content. They also found that increased temperature raised the vapor pressure according to the Clapeyron-Clausius equation (log p = A - B/T, where A and B are constants). They measured the vapor densities of p,p-DDT on sand at 20, 30, and 40°C and found them to be 2.9, 13.6, and 60.2 ng/1. Furthermore, Spencer and Cliath found that DDE and other derivatives of DDT have a higher vapor density than DDT (Table 8.4). DDT therefore probably disappears from soil by first being converted to DDE by microorganisms and soil animals, which then slowly disappear by evaporation. 

Laboratory photolysis experiments were designed to confirm that 2,3,7,8-TCDD contained in the selected scrubber solvent could be reduced to 1 ng/g and to determine the reaction rates of the primary HO constituents and 2,3,7,8-TCDD in that solvent matrix. A previous photolysis process for 2,3,7,8-TCDD used hexane as a solvent (8). The solvent selected for use in the TD/UV process was different - a high boiling (kerosene-like) mixture of isoparaffins. This hydrocarbon solvent was selected because of its very low vapor pressure and water solubility, nontoxic and nonflammable characteristics, relatively low cost, chemical stability, and good solvent properties for HO constituents. A second major difference from earlier IT photolysis studies was the presence in the scrubber solution of significant concentrations of other chlorinated organic reactants (2,4-D and 2,4,5-T) which were also subject to photolysis. In fact, the typical concentration ratio between 2,4-D or... 

Short-chain (SCCPs), medium-chain (MCCPs), and long-chain (LCCPs) CPs all have industrial applications and similar environmental concerns. CPs are viscous, colorless or yellowish dense oils with low vapor pressures, except for those of long carbon chain length with high chlorine content (70%), which are solid. CPs are practically insoluble in water, lower alcohols, glycerol and glycols, but are soluble in chlorinated solvents, aromatic hydrocarbons, ketones, esters, ethers, mineral oils and some cutting oils. They are moderately soluble in unchlorinated aliphatic hydrocarbons [1]. 

The vapor pressure at O is given as 8.8 mm Hg, Dipole moment 0,79. Hydrolyzed by water with the formation of silicoformic anhydride, HjSijOj and HBr. Sol in chlorinated hydrocarbons. 

Electrolytic chlorine from a steel bottle contains small amounts of oxygen, chlorine oxides, nitrogen, carbon monoxide, carbon dioxide, hydrogen chloride, chlorinated hydrocarbons, and moisture. For complete purification, chlorine washed with concentrated sulfuric acid is condensed into a receiver (preferably calibrated) cooled in ether/carbon dioxide, and a regular stream of chlorine is produced by placing the receiver in a bath of ice and water. A safety flask should be placed between the reaction flask and the chlorine supply. Chlorine bombs cool very considerably if chlorine is removed in a rapid stream they should, if that happens, never be warmed above 30°C (vapor pressure of Cl2 at 0° 3.76 atm, at +10° 5.14, at +20° 6.86, at +30° 8.97, and +40° 11.52 atm). 

Chlorinated Hydrocarbons. Properties of some chlorinated hydrocarbon insecticides are given in Table VI. All of the compounds, except for lindane, are insoluble in water. DDT is about ten times more insoluble than the other chlorinated hydrocarbons. The vapor pressure of the compounds are classified as follows low(0.1 -0.9 X 10 mm Hg)—DDT, endrin, and dieldrin, moderate (1.0-9.9 X 10 mm Hg)— toxaphene and aldrin, high (10-99 X 10 mm Hg)—chlordan and lindane, and very high (100-999 X 10" mm Hg)— heptachlor. 

The vapor pressure of the super-cooled liquid is shown to be significantly higher than that of the solid, which would be expected. Melting points are usually available in the literature, however, values for the entropy of fusion, AAf are not as common. Molar heats of vaporization, AH are more likely to be listed, for example, values for this parameter have been compiled for a number of chlorinated aromatic compounds and for aromatic hydrocarbons. For many compounds it has been shown that the entropy of fusion approximates 56 J mol K , and AS/R = 6.79. ... 

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