Environmental Engineering Reference
In-Depth Information
TABLE 3.7
Estimated Surface-Water Hydrolysis Half-Lives and Residency Times (Time for
99%
Removal by Hydrolysis Acting Alone) for Chlorinated Solvents and Solvent Stabilizers
Prone to Hydrolysis in Water
>
Hydrolysis Half-Lives
(Literature Values)
Hydrolysis Half-Lives
(Estimated)
Residency
Time
Chemical Name
References
Solvents
Dichloromethane
260,000 days
5
Very long
Persistent
Methyl chloroform
350 days at 25°C
4
Very long
Persistent
Stabilizers
Epichlorohydrin
8.2 days in distilled water
3
350 years
Persistent
Diepoxybutane
a
—
107 years
Persistent
Glycidol
a
—
63 years
Persistent
Butoxymethyl oxirane
a
—
62 years
Persistent
1,2-Butylene oxide
a
11.6 days; converts to
ethylene glycol
1
3 years
21 years
Propylene oxide
a
11.6 days
1
2.9 years
20 years
Isopropyl acetate
2.4 years at pH 7;
88 days at pH 8
2
2.4 years
17 years
Ethyl acetate
2 years at pH 7 and 25°C
3
1.82 years
13 years
Cyclohexene oxide
a
—
37.5 days
260 days
Styrene oxide
a
—
9 days
63 days
Sources:
[1] Bogyo et al. (1980) and Hoechst Celanese (2006); [2] Harris (1990b); [3] NLM (2006) (note: the Hazardous
Substances Data Bank includes errors in citation and transcription of values from journal articles to online
summaries; where available, original sources were checked); [4] Haag and Mill (1988); and [5] Capel and Larson
(1995).
Notes:
Estimates made with HYDROWIN (USEPA, 2000a), a module in the EPIWIN Suite (USEPA, 2007a). Stabilizer
compounds not appearing in this table (e.g., 1,4-dioxane) are not susceptible to hydrolysis. “Very long” describes
modeled estimates in excess of 1000 years.
a
Epoxides estimated for only acid- or base-catalyzed hydrolysis, not for neutral hydrolysis; underestimation may result.
adsorption. This section reviews the potential for stabilizer compounds' participation in acid-base
interactions in aqueous solution.
The primary chemical attribute describing a compound's potential to participate in acid-base
chemical reactions is its acid dissociation constant,
K
a
, the equilibrium constant for the reaction
HA
+
H
2
O
→
H
3
O
+
+
A
−
, (j)
where HA is an organic chemical associated with a proton H, H
3
O
+
is hydronium, and A
−
is the
organic compound remaining after splitting off one or more hydrogen atoms. The equilibrium
constant
K
a
is the ratio of the activities of the reactants as follows (Lyman et al., 1990):
aa
aa
(
g
M
) (
g
M
)
+
-
+
-
+
+
-
-
HO
A
HO
A
HO
HO
A
A
(3.22)
K
=
,
a
=
1
\
K
=
=
.
2
3
3
3
a
aa
H O
a
a
g
M
2
HA
H O
HA
HA
HA
2
The activity of water is taken as one by convention, and activity is dei ned as the molar activ-
ity coefi cient,
γ
, multiplied by the molar concentration,
M
. The convention for expressing acid
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