Optimization of lignin extraction from bamboo by ultrasound-assisted organosolv pretreatment

For a sustainable biorefinery, reduction in the recalcitrance of lignocellulosic biomass is very crucial for the efficient utilization of each fraction. The present work investigated an integrated pretreatment method to recover high-quality lignin along with the cellulose-rich pulp. An optimization study employing response surface methodology investigated the synergistic effects of ultrasound and organosolv pretreatment from Bambusa tulda (bamboo). The optimal condition (180 degrees C, 55 min, and 30 min sonication) resulted in 65.81 & PLUSMN; 2.40% of lignin yield with 95.37 & PLUSMN; 1.17% purity. A reduction in 7.85% yield and 1.54% purity of lignin with organosolv pretreatment highlighted the efficacy of sonication in lignin extraction. Ultrasound resulted in homolytic cleavage of the lignin-carbohydrate bond that enhanced delignification and increase the cellulose crystallinity. NMR, FTIR, GPC, and TGA of lignin suggested the superiority of sonication in maintaining lignin quality. A significant amount of & beta;-O-4 linkages in extracted lignin is favorable for its subsequent valorization.

Automated summary

In order to achieve a sustainable biorefinery, reducing the recalcitrance of lignocellulosic biomass is crucial. This study investigated an integrated pretreatment method to recover high-quality lignin and cellulose-rich pulp. Optimization studies showed that ultrasound treatment combined with organosolv pretreatment resulted in high lignin yield and purity. Ultrasound treatment enhanced delignification and increased cellulose crystallinity, maintaining the quality of lignin. The extracted lignin contained a significant amount of β-O-4 linkages, which is favorable for downstream valorization.