1,4-Dioxane Chemistry, Uses, and Occurrence - Environmental Investigation and Remediation - page 89

2.3.11 E THER S UPPLEMENTS IN F UELS
Cyclic ethers including 1,4-dioxane and 1,3-dioxolane have been considered for addition to fuels to
enhance the octane value and to reduce the formation of carbon monoxide in automobile exhaust
(Maurer et al., 1999). Ether compounds are sometimes added to racing fuel by karters (hot rodders)
to increase fuel octane. Karters report that it takes 10-15% 1,4-dioxane added to racing fuel to pro-
duce increased octane and yield (Pro-Systems, 2002). Racing rules now prohibit using 1,4-dioxane,
dinitrotoluene, propylene oxide, or nitropropane in racing fuels. 1,4-Dioxane is also banned as a
racing motor oil additive in “XTREME Stock Car” and “Women on Wheels” racing (Susquehanna
Speedway Park, 2006). However, ethers elude detection by the digital fuel meters commonly used
at race tracks to verify fuel composition compliance. 1,4-Dioxane, propylene oxide, nitromethane,
and nitropropane have all been used as “illegal” racing fuel additives. The quantities added vary
according to the whims of the racer.
Amateur racers in the karting community have cautioned against the use of 1,4-dioxane because
it is listed as a carcinogen and is easily absorbed through the skin (Copeland, 2004). Racers devel-
oped test methods to check racing fuels for the presence of banned substances including 1,4-diox-
ane, which is not detected by the widely used Godman DT-15 Digatron meter (a dielectric testing
device used to check racing fuels for polar substances). The method involves adding an acid reagent
and checking for the presence of a white precipitate (the “acid drop test”).
1,4-Dioxane is a l ammable liquid and tends to form explosive peroxides. Its development in glycols
(low parts per million levels), which are used as dehumidifying agents in rei neries, may take place by
condensation. 1,4-Dioxane thus formed gets distilled over with benzene in the rei nery process.
Therefore, it is necessary to identify and determine the levels of 1,4-dioxane in glycols as well as ben-
zene. Gas chromatography (GC) is probably the best technique for this purpose. GC analysis may be
carried out with a l ame ionization detector. Results show that 1,4-dioxane can be reliably determined
down to 2 ppm in glycols and benzene and 1 ppm in toluene (Cortellucci and Dietz, 1999).
2.4 1,4-DIOXANE AS A BY-PRODUCT OF MANUFACTURING
1,4-Dioxane occurs as a reaction by-product in several chemical processes used to produce polyes-
ter, soaps, and plastics. Consequently, waste streams from facilities that produced these products
have included 1,4-dioxane, and some have caused contamination of soil and groundwater in past
decades.
2.4.1 E THOXYLATED S URFACTANTS
1,4-Dioxane is produced as a by-product during the sulfonation reaction with alcohol ethoxylates, a
process used to produce surfactants in a wide variety of soaps and detergents. Ethoxylated alcohols
are used as surfactants, detergents, foaming agents, emulsii ers, and wetting agents. During alcohol
ethoxylation, ethylene oxide is combined and rearranged to form the polymer of ethylene oxide.
This process allows ethylene oxide to dimerize to form diethylene dioxide, that is, 1,4-dioxane. If no
effort is made to control formation of 1,4-dioxane, levels may approach 500 ppm or higher. By con-
trolling mixing ratios, temperature, and other reaction parameters, formation of 1,4-dioxane has
been limited to 30-200 ppm (Stepan Company, 2006). Since 1990, MSDS have reported 1,4-diox-
ane at an “upper bound concentration” or “typical maximum” of less than 15 ppm (Talmage, 1994).
Analyses of surfactants and products containing surfactants have shown rather high levels of
1,4-dioxane associated with surfactants and associated products in the 1980s and 1990s.
Today, the 1,4-dioxane impurity in ethoxylated surfactants is removed through a stripping process
employed during production (ATSDR, 2004). Between 1992 and 1997, the average concentration of
1,4-dioxane in cosmetic i nished products was reported to l uctuate from 14 to 79 ppm (mg/kg)
(ATSDR, 2004). As described in the next section, producers of nonionic surfactants also used