Researchers Seek New Uses for "Black Liquor"

By Linda McGraw
February 22, 2000

Scientists with ARS and Vision Paper, Inc., of Albuquerque, New Mexico, have rolled up their sleeves and dirtied their hands to find new uses for "black liquor," a crude byproduct of pulping kenaf fiber. Twenty-five years ago, ARS scientists at the National Center for Agricultural Utilization Research Center in Peoria, Illinois, developed a process to turn kenaf into newsprint.

Originally from Africa, kenaf is a renewable fiber crop closely related to cotton. It reaches heights of 14 feet in less than seven months. Kenaf stalks provide two to three times more fiber per acre annually than the Southern Pine, a paper industry staple in the U.S. South. U.S. farmers can grow kenaf in place of corn, soybeans, cotton, or rice.

Black liquor is usually burned for fuel or chemical recovery, but often small paper mills can't afford expensive incinerators, according to new crops research leader Thomas P. Abbott. Led by Abbott, the Peoria-based research team, including one employee of Vision Paper, found that chitosan, made from ground-up crab shells, helps turn the dissolved kenaf lignin into a solid cake. The solid cake will be tested as an animal feed pellet binder. The remaining soluble black liquor can be converted to a dry fertilizer that has 22.2 percent nitrogen and is low in sodium. In the overall process, black liquor is turned into salable products instead of greenhouse gases.

Abbott spoke about this work at the meeting Kenaf Fiber for the 21st Century, the 3rd annual conference of the American Kenaf Society in Corpus Christi, Texas, Feb. 24-26.

Scientific contact: Thomas P. Abbott, ARS National Center for Agricultural Utilization Research, Peoria, Ill., phone (309) 681-6533, abbotttp@mail.ncaur.usda.gov .