title: Investigation of biomass degradation mechanism in pretreatment of switchgrass by aqueous ammonia and sodium hydroxide.
abstract: Pretreatment of switchgrass using aqueous ammonia or NaOH was investigated as a means to enhance the enzymatic digestibility. To increase the effectiveness of pretreatment, H(2)O(2) was supplemented with the alkaline reagents. Since H(2)O(2) is unstable at high temperature, low-to-high step-change of temperature was applied, and this scheme was found to be effective in the case of NH(3)/H(2)O(2) treatment. The composition of pretreatment liquid indicates that hemicellulose solubilized during alkaline treatment exists either in the form of oligomers or as lignin-carbohydrate complex (LCC). LCC formation was prominent in ammonia treatment and in NaOH/H(2)O(2) treatment, and that LCC formation protects the hemicelluloses sugars from degradation. Lignin in the pretreatment liquor was precipitated and subjected to TGA and FTIR analyses. TGA data indicate that NaOH-lignin has more uniform structure and higher O/C ratio than ammonia-lignin. FTIR analysis indicates that NaOH-lignin has lower aromatic content but higher guaiacyl type structure than ammonia-lignin.
authors.affiliation: Department of Chemical Engineering, Auburn University, AL 36849, USA.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Gupta
authors.forename: Y Y
authors.initials: YY
authors.lastname: Lee
mesh_terms: D000641:Ammonia / Q000494:pharmacology*; D018533:Biomass; D002241:Carbohydrates / Q000032:analysis; D008031:Lignin / Q000302:isolation & purification; D006109:Poaceae / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D012972:Sodium Hydroxide / Q000494:pharmacology*; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry
chemical_list: D002241:Carbohydrates; D012972:Sodium Hydroxide; D000641:Ammonia; D008031:Lignin