Biofuel Research Journal

Biofuel Research Journal

Enhancing lignocellulosic biorefinery sustainability: mechanisms and optimization of microwave-responsive deep eutectic solvents for rapid delignification

Document Type : Research Paper

Authors
Huan Wang 1, 2
Jiasheng Chen 1
Zhengfei Pei 1
Jinshu Huang 1
Junqi Wang 3
Song Yang 1
Hu Li 1
1 State Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, State-Local Joint Laboratory for Comprehensive Utilization of Biomass, Center for R&D of Fine Chemicals, Guizhou University, Guiyang, Guizhou 550025, China.
2 Guizhou Industry Polytechnic College, Guiyang 551400, China.
3 Department of Earth and Environmental Science, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China.
10.18331/BRJ2025.12.1.3
Abstract
Attaining sustainability and carbon neutrality necessitates a transition towards cleaner biorefinery, while the exploitation of sustainable and eco-friendly pretreatment techniques, as a pivotal stage in lignocellulose biorefinery, represents a challenge. Here, an ultrafast biomass pretreatment strategy enabled by microwave (MW) responsive deep eutectic solvent (DES) is proposed. The solvent properties (Kamlet-Taft parameters) of DES under MW participation are closely correlated with wheat straw fractionation efficiency. The lignin removal exhibits a positive correlation with polarity/polarizability (π*) and hydrogen-bond-donating ability (α), establishing a strong relationship between the tunable DES properties and MW responsiveness. MW reinforces the delignification efficiency of DES with relatively high π* and α, as corroborated by comparative analysis with conventional heating (CH) pretreatment. The reinforcement by MW moderates the pretreatment process and enables ultrafast lignocellulose deconstruction (130 ℃, 150 s, and 96.1% lignin removal), subsequently with 92.4% enzymatic hydrolysis and 8.8 g microbial lipid/100 g wheat straw at a remarkably low severity factor (R0). Life cycle assessment manifests the environmental benefits of MW-assisted DES in mitigating impacts by 63.1%, including global warming potential, resource depletion-fossil fuels, and ecotoxicity, in comparison to CH pretreatment. MW-DES exhibits an economic superiority based on life cycle cost analysis, with pretreatment cost 44.1% lower than CH-DES. The mechanistic insights into MW intensification of DES with specific properties provide a viable protocol for tailoring green solvents with enhanced MW responsiveness for efficient and sustainable biorefineries.

Graphical Abstract

Enhancing lignocellulosic biorefinery sustainability: mechanisms and optimization of microwave-responsive deep eutectic solvents for rapid delignification

Highlights

  • The correlation between solvent properties and fractionation performance under microwave (MW) irradiation was established.
  • MW enhanced the delignification efficiency of DES, particularly with high π* and α values, leading to a 96.1% lignin removal.
  • The optimal ChCl/OA/EG (1:2:2) ratio achieved 96.1% lignin removal in just 150 s at 130°C.
  • MW-DES pretreatment significantly improved enzymatic hydrolysis, with a 92.4% digestibility, and enabled microbial lipid production of 8.8 g/100 g wheat straw.
  • MW-DES reduced environmental impacts by 63.1% and lowered costs by 44.1% compared to CH-DES pretreatment.

Keywords
Biomass pretreatment
Delignification mechanism
Deep eutectic solvent
Microbial lipid
Life cycle assessment
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Biofuel Research Journal
Volume 12, Issue 1 - Serial Number 1
Winter 2025
Pages 2306-2318