Construction of anhydrous two-step organosolv pretreatment of lignocellulosic biomass for efficient lignin membrane-extraction and solvent recovery
Guojie Song,
Chihe Sun,
Yun Hu,
Chen Wang,
Changlei Xia,
Maobing Tu,
Ezhen Zhang,
Pau-Loke Show,
Fubao Sun
Affiliations
Guojie Song
Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University , Wuxi 214122, People’s Republic of China
Chihe Sun
Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University , Wuxi 214122, People’s Republic of China
Yun Hu
Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University , Wuxi 214122, People’s Republic of China
Chen Wang
Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University , Wuxi 214122, People’s Republic of China
Changlei Xia
Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Materials Science and Engineering, Nanjing Forestry University , Nanjing, Jiangsu 210037, People’s Republic of China
Maobing Tu
Department of Chemical and Environmental Engineering, University of Cincinnati , Cincinnati, OH 45221, United States of America
Ezhen Zhang
Institute of Agro-Products Processing Science and Technology, Guangxi Academy of Agricultural Sciences , Nanning 530007, People’s Republic of China
Pau-Loke Show
Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham Malaysia Campus , Jalan Broga Semenyih, Semenyih, Selangor Darul Ehsan 43500, Malaysia
Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University , Wuxi 214122, People’s Republic of China
Glycerol organosolv (GO) pretreatment has been revealed to be potent in selectively deconstructing the lignocellulosic biomass and effectively enhancing its enzymatic hydrolysis, but the conventional solid washing and GO lignin extraction processes frequently consume large amounts of water, resulting additionally in difficulty recycling the glycerol. In this study, an anhydrous two-step organosolv pretreatment process was explored, followed by the membrane ultrafiltration of glycerol lignin. The results showed that the solid washing of the residual glycerol after the atmospheric glycerol organosolv (AGO) pretreatment was necessary for the subsequent operation of high-solid enzymatic hydrolysis. Washing with ethanol was desirable as an alternative to water as only a low glycerol content of 5.2% resided in the substrate. Membrane ultrafiltration was helpful in extracting the AGO lignin from the pretreatment liquor, in which a high lignin extraction of 81.5% was made with a regenerated cellulose membrane (cut-off for 1 kDa) under selected ultrafiltration conditions. With the characterization of membrane-extracted lignin, it was observed for the first time that the AGO lignin has a well-preserved structure of G/S type. Moreover, the lignin was enriched with reactive groups, i.e. β -O-4′ linkages and aliphatic hydroxyl groups, which was very likely due to the glycerol grafting onto the lignin via α -etherification reaction. The two-step organosolv pretreatment process allowed 86% of glycerol and 92% of the ethanol recovery with ∼78% of distillation energy savings, which was applicable for extraction of organosolv lignin and recycling use of organic solvents.
