Comprehensive assessment of elephant grass (Pennisetum purpureum) stalks at different growth stages as raw materials for nanocellulose production

Abstract

Elephant grass, a tropical grass plant, serves dual purposes as forage and as a biomass energy source. This study aimed to identify the optimal raw materials for the production of nanocellulose from elephant grass. Elephant grass stalks harvested during the 2nd, 6th, 8th, and 10th months of growth were pretreated with a deep eutectic solvent (containing choline chloride and oxalic acid in a 1:1 molar ratio) for 3 h at 60 °C, to isolate crude cellulose. The results showed that there were significant differences in the content of chemical components in elephant grass stalks at different growth stages. The cellulose content of elephant grass stalks was highest in the 8th month, reaching 27.4%. Meanwhile, there was no significant difference in lignin content among elephant grass stalks harvested in the 6th, 8th, and 10th months. The isolated crude cellulose from elephant grass stalks harvested in the 8th month exhibited excellent thermal stability, high crystallinity, and a high cellulose content. Thus, the stalks harvested in the 8th month were identified as the optimal raw material for preparing nanocellulose. This study lays the foundation for the production of nanocellulose from elephant grass and provides a theoretical basis for its high-value-added utilization.