Winter may be fading to spring in the northern hemisphere but
the search for nontoxic, inexpensive, and biodegradable deicing
compounds for both jet fuels and wing deicing continues unabated
at the Naval Research Laboratory (NRL) and George Mason University,
Fairfax, Va.
In a scientific paper to be published
in the journal, "Fuel Science and Technology," and
highlighted at the 211th American Chemical Society (ACS) national
meeting in New Orleans, La., March 24-28, scientists from NRL's
Navy Technology Center for Safety and Survivability, Fuels Section,
and George Mason's Chemistry Department, show that acetals and
ketals of reduced sugars represent safe, viable alternatives
to glycol-based additives.
These alternatives are nontoxic
to people and the environment. They are inexpensive, fuel compatible
and biodegradable, and, of utmost importance to aviators and
their passengers, they prevent fuel from icing just as effectively
as do the glycol-based products.
The current fuel system icing
inhibitor additives used in both military aircraft and commercial
airlines are toxic at the concentrations that are required for
effective deicing, according to NRL's Dr. George Mushrush, principal
investigator and also a professor at George Mason University.
Their use is mandatory in all military aircraft fuels and optional
for worldwide aviation fuels depending on routes, flight lengths,
and the season.
"The additives currently
used are ethylene glycol monomethyl ether (EGME) and diethylene
glycol monomethyl ether (DiEGME). When fuel system sumps, filters
and storage tanks are drained, they contain EGME and DiEGME and
therefore create a personnel hazard," Dr. Mushrush said.
"When glycols and their
derivatives are introduced into the environment, they cause the
death of aquatic organisms as dissolved oxygen is depleted by
the high oxygen demand made by glycols as they decompose. The
U.S. EPA is currently developing regulations specifically addressing
the problems associated with deicer runoff," Dr. Mushrush
explained.
NASA, the FAA, and industry officials
have proposed the use of propylene glycol-based deicing compounds.
However, these materials have been shown to be unsuitable due
to higher costs per unit effectiveness. These compounds are also
toxic, though less toxic than either EGME or DiEGME, according
to the U.S. Department of Health and Human Services.
According to Dr. Mushrush, "NRL's
approach is to utilize the large U.S. surplus of sugars (which
are carbohydrates) as the basis for the synthesis of biodegradable
deicing compounds. Studies demonstrate that acetals and ketals
synthesized from the reduced mannose sugar are effective icing
inhibitors for aircraft fuel systems.
"At present, the manufacture
of carbohydrates are important to many industries and to the
organic chemical synthesis industry. With such a broad demand,
the basic building blocks of carbohydrate chemistry are industrially
quite inexpensive and readily available.
"The carbohydrate derivatives
show excellent fuel stability and, based on accelerated storages
tests, should remain stable in Jet A or JP-8 fuels for at least
two years. They do not cause preoxidation, and they mimic the
behavior of EGME and DiEGME in JP-8 rig simulator tests."
The authors note that their article
complements the already abundant literature with a new use for
these rather simple compounds.
The paper was authored by Dr.
Mushrush; Mrs. Erna J. Beal, NRL; Mr. Wayne M. Stalick, Dr. Subash
C. Basu, and Mr. J. Eric Slone, all of George Mason University;
and Mr. John Cummings, Naval Air Warfare Center, Trenton, NJ.
The U.S. Naval Research Laboratory is the Navy's full-spectrum corporate laboratory, conducting a broadly based multidisciplinary program of scientific research and advanced technological development. The Laboratory, with a total complement of nearly 2,500 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 85 years and continues to meet the complex technological challenges of today's world. For more information, visit the NRL homepage or join the conversation on Twitter, Facebook, and YouTube.
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