Volatilization from water

Plashcizers dissolved in water may partition or volahlize into the atmosphere or into soil gases. A Henry s Law constant, Kjj, can be used to classify the volatilization of plashcizers from water. Hemy s Law describes the raho of the partial pressure of the vapor phase of an ideal gas, P , to its mole frachon, Xj, in a dilute soluhon  

Hemy s Law constants were compiled for the 23 plasticizers (Table 18.9) However, all of these values were estimates. One method of estimation is to divide the vapor pressure of the liquid plasticizer by its corresponding solubility in water, Sj, at the same temperature  

Some of the values were estimated using the Fragmentation Method. The resulting estimates range over six orders of magnitude. Many of the plasticizers appear to have a low potential (less than 10 atm-m /mole) for volatilization from water hence, volatilization may be a relatively slow process. Note that multiple listings in Table 18.9 for some plasticizers reflects the uncertainty in these estimated constants. For example, the Kjj for di-(2-ethylhexyl) phthalate was reported as 1.1 x 10 by Howard but as 1.3 x 10 in HSDB.5 

River scenario, days Lake scenario, days 

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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. 

Gas phase stripping (purge-and-trap) techniques can iaq>rove the yield of organic volatiles from water or biological fluids by facilitating the transfer of volatiles from the liquid to the gas phase it is also more suitable than dynamic headspace sampling when the sample volume is restricted (320 23,347-351). Tbe technique is used routinely in many laboratorl B for the analysis... 

Air Stripping—Processes in which contaminants are volatilized from water to air in an engineered system, such as a packed tower92 treatment of the resulting contaminated vapor phase may also be required. 

Monkiedje et al. [10] investigated the fate of niclosamide in aquatic system both under laboratory and field conditions. The octanol/watcr partition coefficient (Kaw) of niclosamide was 5.880 x 10 4. Adsorption isotherm studies indicated that the Freundlich parameters (K, n) for niclosamide were 0.02 and 4.93, respectively, for powder activated carbon (PAC), and 9.85 x 10 5 and 2.81, respectively, for silt loam soil. The adsorption coefficient (Aoc) for the drug was 0.02 for PAC, and 4.34 x 10-3 for the same soil. Hydrolysis of niclosamide occurred in distilled water buffer at pH above 7. No photolysis of the drug was observed in water after exposure to long-wave UV light for 4 h. Similarly, neither chemically volatilized from water following 5 h of sample aeration. Under field conditions, niclosamide persisted in ponds for over 14 days. The half-life of niclosamide was 3.40 days. 

Most agricultural pyrethroids have a very low vapor pressure (Vp) - around 10 8 mmHg at an ambient temperature - which is usually measured by the gas saturation method [8] and, therefore, its distribution to an air compartment is considered less important, as listed in Table 1. Tsuzuki [27] has improved the modified Watson method to estimate the vapor pressure of pyrethroids with reasonable precision just from their chemical structures. The volatilization from water can be conveniently evaluated by the Henry s law constant defined as vapor pressure divided by water solubility [28] and the small values of synthetic pyrethroids... 

Endrin ketone may react with photochemically generated hydroxyl radicals in the atmosphere, with an estimated half-life of 1.5 days (SRC 1995a). Available estimated physical/chemical properties of endrin ketone indicate that this compound will not volatilize from water however, significant bioconcentration in aquatic organisms may occur. In soils and sediments, endrin ketone is predicted to be virtually immobile however, detection of endrin ketone in groundwater and leachate samples at some hazardous waste sites suggests limited mobility of endrin ketone in certain soils (HazDat 1996). No other information could be found in the available literature on the environmental fate of endrin ketone in water, sediment, or soil. 

Based on its very small calculated Henry s law constant of 4.0xl07-5.4xl0"7 atm-m3/mol (see Table 3-2) and its strong adsorption to sediment particles, endrin would be expected to partition very little from water into air (Thomas 1990). The half-life for volatilization of endrin from a model river 1 meter deep, flowing 1 meter per second, with a wind speed of 3 meters per second, was estimated to be 9.6 days whereas, a half-life of greater than 4 years has been estimated for volatilization of endrin from a model pond (Howard 1991). Adsorption of endrin to sediment may reduce the rate of volatilization from water. 

Thomas RG. 1982. Volatilization from water. Handbook of Chemical Proper Estimation Methods, 15-1-15-34. 

Physical and Chemical Properties. The physical and chemical properties of bromomethane are sufficiently well known to allow estimation of environmental fate. Although there is some disparity in reported values for the solubility in water and Henry s law constant for bromomethane (see Table 3-1), further studies to define these parameters more precisely do not appear essential, since volatilization from water is so rapid. 

Despite the advantages, there is concern over the use of such containment methods because the fate of pesticides put into such sites is not well known ( 1 ). One such fate process is volatilization from the disposal site. Organophosphorus pesticide volatilization from water and soil is relatively unlnvestlgated, and if this route of loss occurs to an appreciable extent from disposal sites, a local respiratory hazard may exist. 

In this paper, the volatilization of five organophosphorus pesticides from model soil pits and evaporation ponds is measured and predicted. A simple environmental chamber is used to obtain volatilization measurements. The use of the two-film model for predicting volatilization rates of organics from water is illustrated, and agreement between experimental and predicted rate constants is evaluated. Comparative volatilization studies are described using model water, soil-water, and soil disposal systems, and the results are compared to predictions of EXAMS, a popular computer code for predicting the fate of organics in aquatic systems. Finally, the experimental effect of Triton X-100, an emulsifier, on pesticide volatilization from water is presented. 

Volatilization from Water, Soil-Water, and Soil Systems... 

A simple environmental chamber is quite useful for obtaining volatilization data for model soil and water disposal systems. It was found that volatilization of low solubility pesticides occurred to a greater extent from water than from soil, and could be a major route of loss of some pesticides from evaporation ponds. Henry s law constants in the range studied gave good estimations of relative volatilization rates from water. Absolute volatilization rates from water could be predicted from measured water loss rates or from simple wind speed measurements. The EXAMS computer code was able to estimate volatilization from water, water-soil, and wet soil systems. Because of its ability to calculate volatilization from wind speed measurements, it has the potential of being applied to full-scale evaporation ponds and soil pits. 

X 10 3 atm-m /mol. Therefore, It Is more volatile from water than any other pesticide discussed In this paper. 

Since 1,3-DNB has a very low vapor pressure, insignificant amounts would volatilize from water (HSDB 1994 Lyman et al. 1982). Therefore, the amount of 1,3-DNB that might enter the air through evaporation from aquatic effluent streams would be minuscule. 

Verschueren 1983). The magnitude of the estimated Henry s law constant (4.4-7.7x10 atm- m /mole) indicates that 2-hexanone will volatilize from water, with a half-life in river water of about 10-15 days (Mabey et al. 1982). Volatilization will be slower from lakes or ponds (Mabey et al. 1982). There is no information on whether 2-hexanone in water is expected to partition to soils and sediments. 

Thomas RG. 1990. Volatilization from water. In Lyman, WI, Rheehl, WF, Rosenblatt, DH, eds. Handbook of Chemical Property Estimation Methods. American Chemical Society, Washington, DC. 7-4. 

However, there is little information on the potential for organotins to volatilize from water. There was no indication that tributyltin in water partitioned to the air during a 62-day period whereas 20% of the water evaporated (Maguire et al. 1983). 

G. Bengtson and K.W. Boddeker, Pervaporation of Low Volatiles from Water, in Proceedings of Third International Conference on Pervaporation Processes in the Chemical Industry, R. Bakish (ed.), Bakish Materials Corp., Englewood, NJ, pp. 439-448. 

Environmental Fate. Elemental phosphorus partitions from water to sediment (Berkowitz et al. 1981) transporting elemental phosphorus to sediment. Volatilization from water and soil transports small amounts of elemental phosphorus to air (Spanggord et al. 1985 ... 

Predicted and calculated flux of fenitrothion from water were similar although values were arrived at independently. Both results suggest that volatilization from water is slow compared to other paths of degradation of the insecticide which confirms predictions of the two-film theory of volatilization (17)(18). Losses of fenitrothion from surface films have been shown to be very rapid (2 ) but a surface film was not formed in the present work because the insecticide was mixed into the upper 10 cm of the water column. 

Thomas, R.G. (1982) Volatilization from water. Chapter 15. In Handbook of Chemical Property Estimation Methods, Environmental Behavior of Organic Compounds. Lyman, W.J., Reehl, W.F., Rosenblatt, D.H., Editors, McGraw-Hill, New York. Thompson, H.W., Linnett, J.W. (1936) Trans. Farad. Soc. 32, 681. 

In water, DEHP is predominantly sorbed to suspended particulates and sediments, but some remains dissolved in the aqueous phase. Volatilization is not a dominant transport process. Volatilization from water and soil is not expected to be important, based on the bw Hairy s law constant (estimated value 1.71xl0 5 atm-m3/mol Staples et al. 1997). It has been estimated that the evaporative half-life of DEHP from water would be about 15 years (EPA 1979), and that only about 2% of DEHP loading of lakes and ponds would be volatilized (Wolfe et al. 1980a). 

Volatilization volatilization from water is negligible, calculated volatilization t,2 = 660 d (from 1 cm) and t,2 = 7.1 yr (from 10 cm) from soil (Howard 1991). 

Volatile chemicals reach the atmosphere via direct emission to the air or by volatilization from water, soil, surfaces, and plant and animal respiration. Once in the air, diffusion, advection, and precipitation or deposition are the major sources of movement. 

Since chromium compounds cannot volatilize from water, transport of chromium from water to the atmosphere is not likely, except by transport in windblown sea sprays. Most of the chromium released... 

The partitioning of 2-nitrophenol and 4-nitrophenol from water to air and different aquatic phases will depend on its volatility from water to air and its distribution between water, sediment, and biota. Experimental volatilization rates for either of the compounds from water are unavailable. 

The modeling data based on nonsteady-state equilibrium predict that volatilization of 4-nitrophenol will be insignificant (Yoshida et al. 1983). The Henry s law constant (H) values for these two compounds (see Table 3-2) and the volatility characteristics associated with various H values (Thomas 1982) can be used to predict that volatilization from water will not be important. The dissociation constant (pKa) values of the two compounds (see Table 3-2) indicate that significant fractions of these nitrophenols will be dissociated at pHs above 6. Since ionic species do not volatilize significantly from water, the ionization may further limit volatilization. 

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