To enhance the sustainability of lignocellulosic biomass utilization process, a significant attention is given to a high-value lignin byproduct of this process. Herein, antimicrobial, antioxidant, and physicochemical properties of lignin in black liquor extracted from sugarcane leaf (SCL) for levulinic acid (LA) and hydrochar production were investigated. The lignin was extracted from SCL through an alkaline pretreatment process using 5–25 wt% of either NaOH or KOH at 120–160 °C. Disk diffusion susceptibility tests, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) revealed that the SCL lignin is effective against Gram-positive bacteria () rather than Gram-negative bacteria ( and ). Different alkaline reagents marginally affected the antimicrobial and antioxidant activities of the lignin. Py-GC/MS analysis results determined that the SCL lignin contained mainly -hydroxyphenyl (H) and guaiacyl (G) with a small amount of syringyl (S) lignin. Furthermore, the structural alterations and linkages of SCL lignin during alkaline pretreatment were examined using 2D-HSQC NMR, providing valuable insights into the transformation processes. The conversion of delignified SCL to LA through a catalytic hydrothermal process using various acid catalysts indicated that the alkaline pretreatment could enhance LA yield with a maximum yield of 33.4 wt%. Additionally, fuel property characterization of the hydrochar co-product from LA production determined that the hydrochar can be used as a coal substitute.

中文翻译：

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甘蔗叶转化为乙酰丙酸和氢炭的木质素副产物的抗菌和抗氧化活性

为了提高木质纤维素生物质利用过程的可持续性，该过程的高价值木质素副产品受到了极大的关注。在此，研究了从甘蔗叶 (SCL) 中提取的用于乙酰丙酸 (LA) 和氢炭生产的黑液中木质素的抗菌、抗氧化和理化特性。使用 5-25 wt% 的 NaOH 或 KOH 在 120-160 °C 下通过碱性预处理工艺从 SCL 中提取木质素。纸片扩散药敏试验、最低抑菌浓度 (MIC) 和最低杀菌浓度 (MBC) 表明，SCL 木质素对革兰氏阳性菌 () 而对革兰氏阴性菌 ( 和 ) 有效。不同的碱性试剂对木质素的抗菌和抗氧化活性影响很小。 Py-GC/MS分析结果表明，SCL木质素主要含有β-羟基苯基(H)和愈创木基(G)，以及少量紫丁香基(S)木质素。此外，使用 2D-HSQC NMR 检查了碱性预处理过程中 SCL 木质素的结构变化和连接，为转化过程提供了有价值的见解。使用各种酸催化剂通过催化水热工艺将脱木质素的 SCL 转化为 LA，表明碱性预处理可以提高 LA 的产率，最大产率可达 33.4 wt%。此外，来自 LA 生产的氢炭副产品的燃料特性表征确定该氢炭可以用作煤炭替代品。