ARS | Publication request: Comparing corn stover and switchgrass biochar: characterization and sorption properties

Submitted to: Canadian Journal of Agricultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 9, 2012
Publication Date: December 13, 2012
Citation: Peterson, S.C., Appell, M.D., Jackson, M.A., Boateng, A.A. 2012. Comparing corn stover and switchgrass biochar: characterization and sorption properties. Canadian Journal of Agricultural Science. v. 5(1):1-8.

Interpretive Summary: Biochar is a renewable resource that can be produced from any organic material (crop stovers, grasses, manure, etc.). In this work a very simple and affordable milling process was carried out on two different biochars and then the biochars were tested for their ability to absorb estrogen-like chemical compounds. Estrogen-like compounds, which find their way into wastewater due to their extensive use as hormonal and birth-control medication, can cause severe problems in the food chain because they have serious effects on fish and other aquatic wildlife. Typically these compounds are removed from wastewater with activated carbon or expensive, custom-designed polymer materials. This work studies some of the properties of biochar to see if it could also absorb estrogen-like compounds, and if so, what properties increase its effectiveness. Since it is renewable and there may be no need to chemically activate it (an extra processing cost for activated carbon), this work will lead to new possibilities of biochar as an absorbent material for wastewater purification applications.

Technical Abstract: A switchgrass biochar (SB) produced by fast pyrolysis and a corn stover biochar (CSB) from a slow pyrolysis process were mechanically milled and characterized. Both of these biochars are very cost-effective and originate as residues from bioenergy production and the corn industry, respectively. These two biochars were evaluated for their sorptive properties with both water and the estrogen containing compounds estrone, beta-estradiol, and zearalenone via batch rebinding assays in salt solutions. Although CSB had greater total surface area than SB, SB was a more porous biochar, indicated by its greater micropore surface area. For both water and all estrogen containing compounds, SB had better sorptive capability, most likely due to its higher micropore surface area. These results suggest ball milled biochars from switchgrass and corn stover offer promise for a sustainable approach to removing toxins from water.