Oil from soybeans is the usual starting material
for biodiesel. Now, ARS scientists have found commercial potential for the
glycerol that is a byproduct from making biodiesel. Click the image for
more information about it.
New Citric Acid-Based Polymers for Agricultural
Applications By Sharon Durham August 24, 2005
A biodiesel fuel byproduct called glycerol and an agricultural
commodity called citric acid can be chemically combined to produce
biodegradable polymers that could be used in produce packaging and other
products, according to Agricultural Research
Barone, a chemist at the ARS
Quality Laboratory in Beltsville, Md., made the discovery while studying
processes for improving the effectiveness of insecticides that contain citric
acid as an active ingredient. Citric acid washes away very quickly in the
environment, limiting its effectiveness.
Barone found that molecules containing hydrogen and oxygen--such as
glycerol, sorbitol or polyethylene glycol--reacted with citric acid to produce
polymers with citric acid groups in them. The materials formed are
biodegradable polyesters. Further study showed that the viscosity of the
material can range from the consistency of paint to a slow-to-dissolve,
glasslike product, depending on how the chemical reaction takes place.
The new biodegradable polymers may provide the biodiesel industry with
a new use for glycerol, which is now disposed of after the biodiesel is made.
In addition, citric acid is used in the food industry as a retardant to
browning in cut fruits and vegetables. The new citric acid-based polyesters may
prove useful as a packaging material. Studies are under way to determine
whether the new polymers would work as well as pure citric acid in these
ARS is the U.S. Department of
Agriculture's chief scientific research agency.