Structural characterization and comparison of switchgrass ball-milled lignin before and after dilute acid pretreatment.
To reduce the recalcitrance and enhance enzymatic activity, dilute H(2)SO(4) pretreatment was carried out on Alamo switchgrass (Panicum virgatum). Ball-milled lignin was isolated from switchgrass before and after pretreatment. Its structure was characterized by (13)C, HSQC, and (31)P NMR spectroscopy. It was confirmed that ball-milled switchgrass lignin is of HGS type with a considerable amount of p-coumarate and felurate esters of lignin. The major ball-milled lignin interunit was the beta-O-4 linkage, and a minor amount of phenylcoumarin, resinol, and spirodienone units were also present. As a result of the acid pretreatment, there was 36% decrease of beta-O-4 linkage observed. In addition to these changes, the S/G ratio decreases from 0.80 to 0.53.
Samuel
Reichel
R
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA.
Pu
Yunqiao
Y
Raman
Babu
B
Ragauskas
Arthur J
AJ
D000143:Acids / Q000737:chemistry*; D056804:Biofuels; D002850:Chromatography, Gel; D008031:Lignin / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008897:Panicum / Q000737:chemistry*
D000143:Acids; D056804:Biofuels; D008031:Lignin