title: Two-stage pretreatment of rice straw using aqueous ammonia and dilute acid.
abstract: Liberation of fermentable sugars from recalcitrant lignocellulosic biomass is one of the key challenges in production of cellulosic ethanol. Here we developed a two-stage pretreatment process using aqueous ammonia and dilute sulfuric acid in a percolation mode to improve production of fermentable sugars from rice straw. Aqueous NH₃ was used in the first stage which removed lignin selectively but left most of cellulose (97%) and hemicellulose (77%). Dilute acid was applied in the second stage which removed most of hemicellulose, partially disrupted the crystalline structure of cellulose, and thus enhanced enzymatic digestibility of cellulose in the solids remaining. Under the optimal pretreatment conditions, the enzymatic hydrolysis yields of the two-stage treated samples were 96.9% and 90.8% with enzyme loadings of 60 and 15FPU/g of glucan, respectively. The overall sugar conversions of cellulose and hemicellulose into glucose and xylose by enzymatic and acid hydrolysis reached 89.0% and 71.7%, respectively.
authors.affiliation: Samsung Advanced Institute of Technology, Yongin 446-712, Republic of Korea.
authors.forename: Jin-Woo
authors.initials: JW
authors.lastname: Kim
authors.forename: Kyoung Seob
authors.initials: KS
authors.lastname: Kim
authors.forename: Jin-Suk
authors.initials: JS
authors.lastname: Lee
authors.forename: Sung Min
authors.initials: SM
authors.lastname: Park
authors.forename: Hwa-Young
authors.initials: HY
authors.lastname: Cho
authors.forename: Jae Chan
authors.initials: JC
authors.lastname: Park
authors.forename: Jun Seok
authors.initials: JS
authors.lastname: Kim
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D056804:Biofuels; D000431:Ethanol / Q000378:metabolism*; D006868:Hydrolysis; D008031:Lignin / Q000378:metabolism; D012275:Oryza / Q000737:chemistry*; D018547:Plant Stems / Q000737:chemistry*; D013464:Sulfuric Acids / Q000378:metabolism*
chemical_list: D056804:Biofuels; D013464:Sulfuric Acids; C036909:lignocellulose; D000431:Ethanol; D000641:Ammonia; D008031:Lignin; C033158:sulfuric acid