Efficient pre-treatment of bagasse to enhance the cellulose and lignin valorization by the combination of metal-based ionic liquid and organic acid
Ya-Peng Du, Meng Li, Xiaoping Zheng, Yu Chai, Yan-Zhen Zheng
Abstract
Effective pre-treatment is vital for efficiently separating and utilizing the three primary components of lignocellulose . In this investigation, agricultural by-product bagasse underwent pre-treatment using a system comprising a metal-based ionic liquid ([BMIM][AlCl 4 ]) and the biomass-derived organic acid lactic acid (LA). This combination exhibited a remarkable synergistic effect in removing lignin (72.58 wt%) while preserving cellulose (70.1 wt%) in the solid residues. The mechanism of the synergistic effect of [BMIM][AlCl 4 ] and LA was revealed by density functional theory (DFT) calculations, which elucidated the formation of weak-strength, closed-shell, and electrostatically dominant hydrogen bonds between [BMIM][AlCl 4 ]/LA and lignin. [BMIM][AlCl 4 ] and LA interacted with lignin simultaneously, significantly contributing to lignin dissolution. The removal of lignin and cellulose retention without disrupting the cellulose structure was confirmed through characterization using FTIR, SEM, and XRD techniques. Besides, the pre-treatment effectively broke down the barrier to degradation, enhancing the conversion yield of cellulose into the important platform molecule levulinic acid. Additionally, the regenerated lignin, with small molecular weight and nanometer particle size, demonstrated high antioxidant and antibacterial properties . Overall, this study provides insights into the development of ionic liquid-organic acid pre-treatment strategies for efficiently converting agricultural waste into biofuels, biochemicals, and bio-based materials.