ARS scientists in New Orleans are turning ordinary
agricultural byproductslike soybean hulls and corn husksinto
extraordinary, pollution-fighting materials. Here, for an earlier study,
chemists Wayne Marshall and Lynda Wartelle analyze nutshell carbons to find out
their adsorbing power. Click the image for more information about
Soybean Scraps: Nature's Pollution Solution?
By Erin Peabody
June 21, 2006
The answer to tomorrows water
pollution problems could come from soybeans, according to Agricultural Research
Service (ARS) scientists. Not from the
tender legumes themselves, but from the overly abundant hulls that typically
end up as a livestock feed.
Wartelle have discovered that these undervalued hullsas well as
leftover stalks and stems from already-plucked corn and sugarcane
plantsmake the ideal foundation for a potent filtering agent that can
adsorb harmful levels of lead, chromium, copper and cadmium from contaminated
Marshall and Wartellewho work at the ARS Southern Regional Research
in New Orleans, La.have found that it takes just two simple steps to
convert these cheap and abundant crop residues into a powerful magnet capable
of snagging both positively- and negatively-charged particles of heavy metals
The material that theyve succeeded in creating is known as a
dual-functioning ion exchange resin. These resinswhich are commonly used
for treating industrial and municipal waste waters and for recycling heavy
metals from solutionsare typically effective in capturing only one kind
of particle with either a positive or negative charge.
But the SRRC researchers resins can grab both. And Marshall has found
that theyre more cost-effective than two synthetically-made resins
currently in use.
Ion exchange resins work by swapping, or exchanging, the undesirable ions in
a water supply with benign ones. In a classic example of this interplay, water
softeners work by drawing out and replacing unwanted hard water
particles, like calcium and magnesium, with ions from sodium.
Marshall and Wartelle give their plant residues a negative charge by adding
citric acid, a common food industry additive. The positive charge comes from
choline chloride, which the researchers bind to plant fibers by adding DMDHEU
(or dimethyloldihydroxyethylene urea)a chemical thats already known
for making molecules stick. In the textile industry, its the compound
that helps dye cling to cotton and wool fibers.
ARS is the U.S. Department of
Agricultures chief scientific research agency.