Historical Use of Chlorinated Solvents and Their Stabilizing Compounds - Environmental Investigation and Remediation - page 56

TABLE 1.25
Partitioning of Trichloroethylene Stabilizers from New and Spent Solvent, Robbins Air
Force Base

Solvent 1,2-Butylene Oxide a Epichlorohydrin Ethyl Acetate Methyl Pyrrole

New trichloroethylene 1.64 1.66 34.6 15.9

Spent trichloroethylene 0.685 1.69 28.5 21.8

Percent change b

−58 +2 −18 +37

Source: Tarrer, A.R., Donahue, B.A., Dhamavaram, S., and Joshi, S.B., 1989, Reclamation and Reprocessing of Spent
Solvents . Park Ridge, NJ: Noyes Data Corporation.

Concentrations expressed as wt% × 103.

a

Decreases are due to loss of stabilizer.

b

retained in the liquid phase; adding nitroethane therefore inversely complements the behavior of
nitromethane (Spencer and Archer, 1981).
In TCE, similar apportioning of stabilizer compounds has been measured. Samples of new and
spent TCE from Robins Air Force Base outside Macon, Georgia, were analyzed by Tarrer et al. (1989);
results are summarized in Table 1.25. Epichlorohydrin remained essentially unchanged, 1,2-butylene
oxide decreased by 58%, ethyl acetate decreased by 18%, and methyl pyrrole increased by 37%.
Stabilizers used in perchloroethylene are also subject to partitioning because of boiling-point
differences. Samples of new and spent perchloroethylene from a degreasing operation at Kelly Air
Force Base near San Antonio, Texas, were analyzed and reported in Alfred Tarrer's topic,
Reclamation and Reprocessing of Spent Solvents (Tarrer et al., 1989). Cyclohexene oxide is negli-
gibly diminished by about 6%, whereas n -BGE increases by about 75%. Table 1.26 presents data on
the partitioning of perchloroethylene stabilizers from new and spent solvents.
Aniline and morpholine, both claimed in patents as stabilizers for perchloroethylene, boil at
higher temperatures than perchloroethylene. Amines such as aniline react to form anilidine, an
undesired impurity that is retained in the distillation residue (Skeeters, 1960b). Aniline was one of
the earliest stabilizers for chlorinated solvents (Ellis, 1925). It was also one of the earliest stabilizers
for which toxicity and worker health and safety issues were raised (Dinley, 1937).
Boiling point and vapor pressure are integrally linked parameters. Both should be considered
when weighing whether partitioning of a stabilizer from its solvent will likely occur.
Other impurities in solvents can also be partitioned because of boiling-point differences. For
example, one of the methods of producing TCE also produces perchloroethylene (Shepherd, 1962).
If perchloroethylene is carried over as a minor impurity into TCE, the perchloroethylene is

TABLE 1.26
Partitioning of Perchloroethylene Stabilizers from New and Spent Solvent, Robbins Air
Force Base

Solvent Cyclohexene Oxide Butoxymethyl Oxirane a

New perchloroethylene 1.06 4.26

Spent perchloroethylene 0.998 7.45

Percent change (%)

−6 +75

Source: Tarrer, A.R., Donahue, B.A., Dhamavaram, S., and Joshi, S.B., 1989, Reclamation and Reprocessing of Spent
Solvents . Park Ridge, NJ: Noyes Data Corporation.
Note: Concentrations expressed as wt% × 10 3 .
a Also called n -BGE; 1-butoxy-2,3-epoxypropane; 1-butoxy-2,3-epoxypropane; and 2,3-epoxypropyl butyl ether.