Volatilization of organic compounds

There is more current literature which speaks to exactly this point. Hassett -0 has found that the sorption of organic compounds from water to suspended particles is altered in the presence of dissolved organic carbon. Griffin Chian - - and Diachenko have found that the volatility of organic compounds in water decreases when humic materials are present. Perdue -2 has found that the rate of hydrolysis of the octyl ester of 2,4-D is decreased in the presence of humic materials. 

Voutsas E, Vavva C, Magoulas K, Tassios D (2005) Estimation of the volatilization of organic compounds from soil surfaces. Chemosphere 58 751-758... 

Abiotic transformation of contaminants in subsurface natural waters result mainly from hydrolysis or redox reactions and, to lesser extent, from photolysis reactions. Complexation with natnral or anthropogenic ligands, as well as differential volatilization of organic compounds from multicomponent hquids or mixing with toxic electrolyte aqueous solutions, may also lead to changes in contaminant properties and their environmental effects. Before presenting an overview of the reactions involved in contaminant transformations, we discuss the main chemical and environmental factors that control these processes. 

Common to nearly all analyses is preservation with refrigeration at 2-6°C, a practice, which minimizes the volatilization of organic compounds with low boiling points and the bacterial degradation of most organic compounds. That is why we must place samples on ice immediately after they have been collected, ship them in insulated coolers with ice, and keep them refrigerated until the time of analysis. Water samples collected for metal analysis and preserved with nitric acid are an exception to this rule as they may be stored at room temperature. The addition of methanol or sodium bisulfate solution to soil collected for VOC analysis is the only chemical preservation techniques ever applied to soil samples. 

Contaminants in ambient air result in inhalation exposure either when the child is outdoors and breathes contaminated air or when contaminants in the air are transported indoors where the child spends time. Adverse health effects (acute and chronic) associated with inhalation of air contaminants are a common concern for people living in polluted cities, near hazardous waste sites, or close to point sources like smelters (Figure 15). Air emissions from past or current production processes, as well as volatilization of organic compounds, airborne particulates, and acid gases, may expose residents to contaminants at levels of health concern (ATSDR, 1994). In urban areas, mobile sources contribute substantially to organic, inorganic, and particulate air pollution. Fires, open burning, and wind-blown dust can also be major sources of ambient air pollution. 

Repeat the same experiment with dry soil vs. moistened soil. Water content of soil is the most important factor for volatilization of organic compounds. In very wet soil, organic compounds desorb from soil (Vander Wall 2003). 

LaRegina J, Bozzelli JW, Harkov R, et al. 1986. Volatility of organic compounds at hazardous waste sites and a sanitary landfill in New Jersey. An up-to-date review of the present situation. Environ Prog 5 18-27. 

Current mathematical descriptions of the volatilization process date from the pioneering work of Whitman (39), who in the 1920s demonstrated that a two-film or two-resistance model gave an adequate description of interphase transfer processes of this type. Liss (16) and Liss and Slater (20) applied this concept to environmental transfer processes in the 1970s, and the concept was also used by Mackay and Leinonen (24) and Mackay (2/) in describing volatilization of organic compounds. Volatilization is placed in context with other environmental transport processes in the text by Thibodeaux (36). 

The VBS provides a convenient framework for organic dynamics in addition to equilibrium partitioning because equilibrium is a balance between condensation (the molecular flux from the gas to the particle phase) and evaporation (the molecular flux from the particle phase to the gas). The difference between the vapor concentrations at the particle surface and far away from it serves as a driving force for net condensation or evaporation. Because the particle surface is usually assumed to be in equilibrium with the gas phase adjacent to it, evaporation depends explicitly on volatility. Condensation on the other hand depends only on the collision rate of molecules with the surface and so it is first order independent of volatility. The volatility of organic compounds thus affects the aerosol growth dynamics specifically through its influence on the evaporation term in the driving force for mass transport. 

Cho, H. J. and P. R. Jaffe. 1990. The volatilization of organic compounds in unsaturated porous media during infiltration. Journal of Contaminant Hydrology 6, 387-410. 

Thermal chromatography Volatilization of organic compounds at high temperatures and their separation by chromatographic techniques such as TLC. 

Separations based upon differences in the physical properties of the components. When procedures (1) or (2) are unsatisfactory for the separation of a mixture of organic compounds, purely physical methods may be employed. Thus a mixture of volatile liquids may be fractionally distilled (compare Sections 11,15 and 11,17) the degree of separation may be determined by the range of boiling points and/or the refractive indices and densities of the different fractions that are collected. A mixture of non-volatile sohds may frequently be separated by making use of the differences in solubilities in inert solvents the separation is usually controlled by m.p. determinations. Sometimes one of the components of the mixture is volatile and can be separated by sublimation (see Section 11,45). 

Many mercury compounds are labile and easily decomposed by light, heat, and reducing agents. In the presence of organic compounds of weak reducing activity, such as amines (qv), aldehydes (qv), and ketones (qv), compounds of lower oxidation state and mercury metal are often formed. Only a few mercury compounds, eg, mercuric bromide/77< 5 7-/7, mercurous chloride, mercuric s A ide[1344-48-5] and mercurous iodide [15385-57-6] are volatile and capable of purification by sublimation. This innate lack of stabiUty in mercury compounds makes the recovery of mercury from various wastes that accumulate with the production of compounds of economic and commercial importance relatively easy (see Recycling). 

Sublimation. This process is employed to separate volatile substances from non-volatile impurities. Iodine, arsenic(III) oxide, ammonium chloride and a number of organic compounds can be purified in this way. The material to be purified is gently heated in a porcelain dish, and the vapour produced is condensed on a flask which is kept cool by circulating cold water inside it. 

Hazards arising from the oxidation of organic compounds are greater when the reactants are volatile, or present as a dust or an aerosol. Liquid oxygen and various concentrated acids, e.g. nitric, sulphuric or perchloric acid, and chromic acid are strong oxidizing agents. The use of perchloric acid or perchlorates has resulted in numerous explosions their use should be avoided when possible (refer to Table 6.5). 

Pfaffenberger CD, Peoples AJ, Enos HF. 1980. Distribution of volatile halogenated organic compounds between rat blood serum and adipose tissue. Int J Environ Anal Chem 8 55-65. 

Thomas RG. 1982. Volatilization from water. In Lyman WJ, Reehl WF, Rosenblatt DH, eds. Handbook of chemical property estimation methods Environmental behavior of organic compounds. New York McGraw Hill Book Co., Ch. 15. 

Soil vapor extraction (SVE) is a relatively new yet widely applied technology for the remediation of soils contaminated with volatile organic compounds (VOC) in the unsaturated zone above the water table (vadose zone). The process consists of generating an airstream through the contaminated soil subsurface in order to enhance the volatilization of organic contaminants and thus remove them from the soil matrix.913... 

Most gasoline constituents are volatile organics. Volatilization depends on the potential volatility of the compounds and on the soil and environmental conditions, which modify the vapor pressure of the chemicals. Factors affecting volatility are water content, clay content, surface area, temperature, surface wind speed, evaporation rate, and precipitation. 

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