Comparisons of alkali, organosolv and deep eutectic solvent pre-treatments on the physiochemical changes and lignin recovery of oak and pine wood

Mao, Yujie; Tarhanli, Ilayda; Owen, Gwyn; Lee, Chai Siah; Senses, Erkan; Binner, Eleanor

Abstract

Pre-treatment is a crucial and the most energy-intensive step for successful valorisation of lignocellulosic biomass in a biorefinery. This study provides systematic comparisons of the biomass fractionation and physiochemical changes of oak and pine wood waste using three pre-treatment methods: 1). an alkali process (2.5 M NaOH and 0.4 M Na2S), 2). an Organosolv process (70 % ethanol in water with 1 % w/w H2SO4), and 3). an emerging Deep Eutectic Solvent (DES) process (p-Toluenesulfonic acid: Choline Chloride: Glycerol in 2:1:1 molar ratio). Among the three pre-treatments, DES exhibits the highest process efficiency, achieving a solid residue weight loss of 43.5 % (oak) and 35.3 % (pine) corresponding to the highest delignification yield of 66.1 % (oak) and 79.2 % (pine) at a much shorter time (30 min vs 180 min) and less energy consumption (1/5 to 1/8) than alkali and Organosolv. DES-treated wood shows higher sensitivity to thermal degradation at lower temperatures, indicating better potential as a solid fuel. It also shows a lower degree of crystallinity of 28.6 % (oak) and 26.7 % (pine) and higher phenolic content, suggesting potentially better enzymatic susceptibility during bioconversion. On the contrary, Organosolv-treated wood presents preserved crystallinity of 41.6 % (oak) and 35.5 % (pine) and macro-/nano-structures, indicating potentially better mechanical properties for functional materials. It is hoped that this study will provide insights to informing sustainable solvent selections in biorefinery and biomass product development for value-added applications.

Citation

Mao, Y., Tarhanli, I., Owen, G., Lee, C. S., Senses, E., & Binner, E. (2025). Comparisons of alkali, organosolv and deep eutectic solvent pre-treatments on the physiochemical changes and lignin recovery of oak and pine wood. Industrial Crops and Products, 226, Article 120614. https://doi.org/10.1016/j.indcrop.2025.120614

• Journal Article Type: Article
• Acceptance Date: Jan 25, 2025
• Online Publication Date: Feb 7, 2025
• Publication Date: 2025-04
• Deposit Date: Apr 11, 2025
• Publicly Available Date: Apr 11, 2025
• Journal: Industrial Crops and Products
• Print ISSN: 0926-6690
• Electronic ISSN: 1872-633X
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 226
• Article Number: 120614
• DOI: https://doi.org/10.1016/j.indcrop.2025.120614
• Keywords: Lignocellulosic biomass, Pre-treatment, Deep Eutectic Solvents, Microwave-assisted extraction, Delignification, Physiochemical property
• Public URL: https://nottingham-repository.worktribe.com/output/45161485
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0926669025001608
• Additional Information: This article is maintained by: Elsevier; Article Title: Comparisons of alkali, organosolv and deep eutectic solvent pre-treatments on the physiochemical changes and lignin recovery of oak and pine wood; Journal Title: Industrial Crops and Products; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.indcrop.2025.120614; Content Type: article; Copyright: © 2025 The Author(s). Published by Elsevier B.V.