
Soybean Hulls
Eyed for Wastewater FilteringBy Jan Suszkiw April 3, 2001Soybean hulls, the seeds fiber
coat, show promise as a new filter for removing toxic metals from industrial
wastewater, an Agricultural Research
Service scientist reported Monday at the American Chemical Societys 221st national
meeting in San Diego, Calif. According to ARS chemist Lynda Wartelle, soybean hulls are a low-value,
high-volume agricultural waste that can be rendered into metal adsorbents
comparable to commercial products called ion exchange resins. The key lies in a
new process she and colleagues devised that changes the hulls properties
and surface charge using food- grade citric acid combined with a heating step. Wartelle is based at the ARS
Southern
Regional Research Center, New Orleans, La. Her colleagues are research
chemist Wayne Marshall, also at SRRC in New Orleans; cost engineer Andrew
McAloon, ARS Eastern Regional Research
Center, Wyndmoor, Pa.; and engineering technician Alexandra Chatters,
currently at Xavier University of Louisiana.
Soybean hulls, produced in the U.S. at the rate of 10 to 15 billion pounds
annually, are typically sold to animal feed supplement producers for $40 a ton.
But scientists envision increasing the hulls worth by turning them into
adsorbent filters used by electroplaters, jewelers and other industries that
generate wastewater with metal contaminants. Most commercial ion exchange resins cost between $2 and $20 a pound,
depending on whether theyre synthetic or cellulose-based, according to
Marshall. But in studies Wartelle reported at the ACS meeting, the team
calculates that making adsorbents from 22,000 pounds of soybean hulls per day
costs about 53 cents per pound. And, in trials with solutions containing
cadmium, copper, lead, nickel and zinc, the modified hulls captured
positively-charged ion forms of these metals at rates slightly above comparable
commercial resins. Peat Technologies, Inc., a Cook, Minn., firm, has a material transfer
agreement with ARS to test the soybean hull adsorbents. ARS is the U.S. Department of
Agricultures chief scientific research agency. Scientific contact: Lynda H. Wartelle and Wayne E. Marshall, ARS
Commodity
Utilization Research Unit, Southern Regional Research Center, New Orleans,
La., phone (504) 286-4356, fax (504) 286-4367,
[email protected],
[email protected]. Story contacts Wayne E Marshall Andrew J McAloon Jan R Suszkiw U.S. Department of Agriculture | |