Skip to main content
ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Sustainable Biofuels and Co-products Research » Research » Publications at this Location » Publication #225573
Title: Pretreatment and fractionation of corn stover by S.E.A.A.(Soaking in ethanol and aqueous ammonia)

Author
item KIM, TAE HYUN - IOWA STATE UNIV,AMES
item Nghiem, Nhuan
item Hicks, Kevin

Submitted to: Applied Biochemistry and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2009
Publication Date: 1/29/2009
Citation: Kim, T., Nghiem, N.P., Hicks, K.B. 2009. Pretreatment and fractionation of corn stover by S.E.A.A.(Soaking in ethanol and aqueous ammonia). Applied Biochemistry and Biotechnology. 153:171-179.

Interpretive Summary: Agricultural residues such as corn stover are good feedstocks for production of liquid fuels and industrial chemicals. Bioconversion of these materials require a pretreatment to make them more susceptible to enzymatic attacks, which result in formation of fermentable sugars for the subsequent fermentation step. Most of the pretreatment processes cause loss of the carbohydrate fractions, especially the hemicellulose, which in turn causes lower yields of fermentable sugars. It is highly desirable that as much of the carbohydrates are preserved as possible during the pretreatment. Soaking in Aqueous Ammonia (SAA) is a pretreatment process that preserves virtually all cellulose and 80% hemicellulose in the treated feedstock. In the new process called Soaking in Ethanol and Aqueous Ammonia (SEAA), ethanol is added to the aqueous ammonia solution. The addition of ethanol reduces the loss of hemicellulose in corn stover by solubilization from 20% to only 6% of the original amount. The net result is more fermentable sugars will be available for conversion to ethanol or other bio-based products.

Technical Abstract: A new process for pretreatment of lignocellulosic biomass, called the Soaking in Ethanol and Aqueous Ammonia (SEAA) process, was developed to improve hemicellulose preservation in solid form. In the SEAA process an aqueous ammonia solution containing ethanol is used. Corn stover was treated with 15 wt% ammonia at 1:9 solid:liquid ratio (by weight) at 60oC for 24 hours with ethanol added at 1 wt%, 5 wt%, 20 wt% and 49 wt% (balance was water). The extents by which xylan was solubilized with no ethanol and with ethanol added at 1 wt%, 5 wt%, 20 wt%, and 49 wt% of the total liquid were found to be 17.2%, 16.7%, 14.5%, 10.4%, and 6.3% of the original xylan, respectively. Thus, at the highest ethanol concentration used the loss of hemicellulose in the liquid phase was reduced by 63%. The digestibility of glucan and xylan in the pretreated corn stover samples by cellulase was not affected by ethanol addition up to 20 wt%. The enzymatic digestibility of the corn stover treated with 49 wt% ethanol added was lower than the digestibility of the sample treated with no ethanol addition. Thus, based on these results, 20 wt% was found to be the optimum ethanol concentration for use in the SEAA process.