title: Mechanism of improved cellulosic bio-ethanol production from alfalfa stems via ambient-temperature acid pretreatment.
abstract: Model compounds and recalcitrant biomass were studied to elucidate the mechanism of ambient-temperature acid pretreatment of cellulosic biomass for bio-ethanol production. Pure cellulose, a pure hemicellulose and alfalfa stems were pretreated with sulfuric acid under ambient temperature with varied acid loading and time. Changes in water-soluble carbohydrates (WSCs) and chemical components of substrates were determined, and ethanol production via simultaneous saccharification and fermentation (SSF) was studied. The results showed significant amount of WSCs formed, and the WSCs increased with increasing acid loading and pretreatment time. The ethanol yields from pure cellulose were primarily affected by the added ash. Acid loading showed significant positive effect on ethanol production from alfalfa stems, whereas pretreatment time showed much weaker positive effect. However, non-significant amounts of WSCs were removed by washing of dried substrates. It was hypothesized to be because the WSCs adsorbed onto bulk substrates during the freeze-drying step, as supported by experimental results.
authors.affiliation: Department of Biological System Engineering, University of Wisconsin-Madison, Agricultural Engineering Building, Madison, WI 53706, USA.
authors.forename: Shengfei
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Department of Biological System Engineering, University of Wisconsin-Madison, Agricultural Engineering Building, Madison, WI 53706, USA. Electronic address: trunge@wisc.edu.
authors.forename: Troy M
authors.initials: TM
authors.lastname: Runge
mesh_terms: D000143:Acids / Q000737:chemistry*; D018533:Biomass; D019149:Bioreactors; D002241:Carbohydrates / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D005285:Fermentation; D000455:Medicago sativa / Q000737:chemistry*; D018547:Plant Stems / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry; D013464:Sulfuric Acids / Q000737:chemistry; D013696:Temperature
chemical_list: D000143:Acids; D002241:Carbohydrates; D011134:Polysaccharides; D013464:Sulfuric Acids; D000431:Ethanol; C007916:hemicellulose; D002482:Cellulose; C033158:sulfuric acid
keywords: Alfalfa stems; Ambient-temperature sulfuric acid pretreatment; Cellulosic bio-ethanol; Hemicellulose adsorption; Water-soluble carbohydrates (WSCs)