Deconstruction of oriented crystalline cellulose by novel levulinic acid based deep eutectic solvents pretreatment for improved enzymatic accessibility

Zhe Ling; Zongwei Guo; Caoxing Huang; Lei Yao; Feng Xu

doi:10.1016/j.biortech.2020.123025

Deconstruction of oriented crystalline cellulose by novel levulinic acid based deep eutectic solvents pretreatment for improved enzymatic accessibility

Bioresour Technol. 2020 Jun:305:123025. doi: 10.1016/j.biortech.2020.123025. Epub 2020 Feb 14.

Authors

Zhe Ling¹, Zongwei Guo², Caoxing Huang³, Lei Yao⁴, Feng Xu⁵

Affiliations

¹ Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China; Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China.
² Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China.
³ Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China.
⁴ Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
⁵ Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China. Electronic address: xfx315@bjfu.edu.cn.

PMID: 32114299
DOI: 10.1016/j.biortech.2020.123025

Abstract

Discovering green solvents and their inner mechanisms for efficient deconstruction of lignocellulosic biomass recalcitrance are receiving growing interests. In this work, eco-friendly levulinic acid (LA) based deep eutectic solvents (DES) were proposed for pretreatment on moso bamboo by combining acetamide (Am), betaine (Ba) and choline chloride (ChCl) as hydrogen bonding acceptors. LA/ChCl pretreated materials showed optimal enzymatic accessibility with the highest glucose yield (79.07%) because of its higher lignin removal, morphological disruption and decreased crystallinity. Moreover, the microvoids (averagely 30 nm) and cracks were observed for cellulose microfibrils in anisotropic directions, which resulted in shorter microfibrils and crystallites facilitating the enzymatic hydrolysis. The studies on recyclability revealed that LA/Ba DES had better recycling performance due to its maintaining capability of lignin extraction. Series of supramolecular changes on oriented crystalline cellulose were determined in this work by novel LA based DES, which may provide new alternatives for biomass pretreatments.

Keywords: Anisotropic deconstruction; Oriented crystalline cellulose; levulinic acid, DES pretreatment.