Abstract
The effects of hydrothermal pretreatment (170–180 °C, 30–60 min) on the structural characteristics of enzymatic and extracted lignin from Triarrhena lutarioriparia (TL) during the integrated delignification process have been comprehensively investigated. Ion chromatography and NMR characterization showed that liquid products after mild hydrothermal process (170 °C, 30 min) were mainly composed of xylooligosaccharide (XOS) with different degrees of polymerization (DP ≥ 2). In addition, the structural changes of lignin during hydrothermal pretreatment and organic acid delignification process have been demonstrated by quantitative 2D heteronuclear single quantum coherence (2D-HSQC) and 31P-NMR techniques. Results showed that the structural changes of lignin (e.g., cleavage of β-O-4 linkages) induced by the hydrothermal pretreatment will facilitate the subsequent organic acid delignification process, and acetylated lignin could be obtained with a considerable yield, which can be used in lignin-based composite and candidate feedstock for catalytic upgrading of lignin. In short, the proposed process facilitates the producing of XOS and acetylated lignin for lignin valorization.
Highlights
With the depletion of fossil fuels, the current dependence on these non-renewable resources needs to be reduced
The increased S/G ratio of the substrates after the hydrothermal pretreatment suggests that G-type lignin units were enriched in the raw materials Triarrhena lutarioriparia (TL), the G-type lignin units were readily fragmented and released from the biomass during the hydrothermal process [37,38], the S/G ratio of lignin in the hydrothermally-treated substrates was increased
The contents of various hydroxyl groups in these Double enzymatic lignin (DEL) samples are essential to investigate the effects of hydrothermal pretreatment on the structural features of lignin
Summary
With the depletion of fossil fuels, the current dependence on these non-renewable resources needs to be reduced. The substitution of fossil fuels by renewable energy is one of the most efficient ways to resolve this problem [1]. Lignocellulosic biomass as a sustainable, abundant, and environmentally friendly energy source, is a primary candidate for the substitution of fuels and chemicals [2]. In the current biorefinery process, there are various barriers, defined as biomass recalcitrance, for the effective conversion of biomass, such as the degree of lignification, the structural heterogeneity and complexity of cell-wall constituents as well as its complex cross-linking [4]. It is necessary to develop a novel method to overcome the cell wall recalcitrance and obtain high-quality lignin for further lignin valorization
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
