Environmental Engineering Reference
In-Depth Information
TABLE 3.9 (continued)
Estimated and Frequently Cited Solubilities of Solvent-Stabilizer Compounds and
Chlorinated Solvents
Commonly
Cited Solubility
b
(mg/L)
Estimated
Solubility,
WATERNT
c
(mg/L)
Temperature for
Commonly Cited
Value (°C)
Stabilizer and Solvent
Compounds
a
References
Cyclohexane
55
43
25
McAuliffe (1966)
Isopentane
48
185
25
Riddick et al. (1985)
Nonylphenol
6
2
25
Shiu et al. (1994)
2,6-di-
tert
-Butyl-
p
-cresol
0.4
6
20
Verschueren (1996)
Diisobutylene
Insoluble in water
12
—
Lide (2000)
a
Nonitalics compounds are stabilizers. Italics compounds are chlorinated solvents; these are listed for comparison to show
whether the stabilizer is likely to evaporate with the solvent or remain behind in the soil where it can be leached down to
groundwater.
b
Solubility values commonly cited in ChemFate database (SRC, 2007b) and the Hazardous Substances Databank (NLM,
2006).
c
WATERNT™ (USEPA, 2007a) in “Estimations Programs Interface for Windows” (EPI Suite) v. 3.20;
http://www.epa.gov/
oppt/exposure/pubs/episuitedl.htm
values and values estimated by using QSAR techniques (shown in
Table 3.9
) underscore the impor-
tance of reviewing the basis for solubility values listed in data compilations.
Table 3.10
lists estimated and measured solubilities for individual compounds. Stabilizer com-
pounds in a solvent waste mixture dissolve differently than individual compounds when released to
groundwater. Each component in the mixture will partition between the aqueous phase and the
mixture (Verschueren, 1996). Mixtures of organic compounds will dissolve into water according to
their effective solubilities, dei ned by Raoult's law:
S
eff
=
XiS
water
,
(3.26)
where
S
eff
is the effective solubility of a compound in a mixture (lower than the compound's solubil-
ity when measured alone in water),
X
i
is the mole fraction of compound
i
in the mixture, and
S
water
is the compound's single-component aqueous solubility (Banerjee, 1984; Jackson and Dwarakanath,
1999; Jackson and Mariner, 1995). Equation 3.26 applies to mixtures without signii cant cosolvent
effects (Payne et al., 2008). Calculations using an assumed solvent waste composition (based on
information in the solvent recovery and patent literature) yield the effective solubility of 1,4-dioxane
relative to methyl chloroform, nitromethane,
sec
-butyl alcohol, 1,3-dioxolane, 1,2-butylene oxide, and
waste cutting oil (Table 3.10).
Table 3.10 shows that the effective solubility of components in a mixture is considerably reduced
from the individual compound's solubility when measured as a single-component system in pure
water. Also, the effective solubility of 1,4-dioxane is 10,000 times greater than the effective solubil-
ity of methyl chloroform. As a result, 1,4-dioxane will be preferentially removed from the waste
mixture; in effect, groundwater will “suck” the dioxane out of the waste mixture because of this
large difference in effective solubilities. Because 1,4-dioxane will dissolve in groundwater earlier in
time and at a much faster rate, the 1,4-dioxane is likely to lead the other components in the waste
mixture in the migration front emanating from the point of release. Consequently, 1,4-dioxane, if
released in sufi cient quantities, can be expected to migrate farthest and can be found at distances
several times the length of the methyl chloroform plume. This pattern has been observed in many
plumes, as discussed further in
Section 3.4.2
and Chapter 8.
Search WWH ::
Custom Search