Facile production of cellulose nanofibers from raw elephant grass by an aluminum chloride-enhanced acidic deep eutectic solvent

• Published in: International journal of biological macromolecules Vol. 246; p. 125687
• Main Authors: Yuan, Jin-Chao, Huang, Rui, Jiang, Ling-Yan, Liu, Guo-Dao, Liu, Pan-Dao, Xu, Wen-Rong
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.08.2023
• Subjects: Cellulose nanofibrils; Deep eutectic solvent; Elephant grass; Elephant grass; Cellulose nanofibrils; Deep eutectic solvent
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2023.125687

To develop a greener and more efficient method for producing cellulose nanofibers (CNFs) from raw plants, an AlCl3-enhanced ternary deep eutectic solvent, DES2 (consisting of choline chloride, citric acid, and AlCl3·6H2O in a molar ratio of 1:0.4:0.08), was synthesized. Raw elephant grass (EG) was pretreated with DES2, followed by sodium chlorite (NaClO2) bleaching and ultrasonic disruption to extract high-performance CNFs. The DES2 and NaClO2 treatments effectively removed hemicellulose and lignin, achieving removal rates of 99.23 % and 99.62 %, respectively, while maintaining a cellulose content of 78.3 %. DES2 demonstrated easy recyclability and maintained excellent biomass pretreatment performance even after multiple cycles. Following a brief 30-min intermittent ultrasound treatment, the resulting CNFs demonstrated superior crystallinity, increased carboxyl content, and a narrower width distribution compared to CNFs obtained from AlCl3-free DES1. Optimized conditions at 110 °C yielded CNFs with 85.3 % crystallinity, 0.64 mmol/g carboxyl content, 5.15 nm width distribution, and excellent dispersion in water for at least six months. Additionally, CNFs enhanced the tensile strength of chia seed mucilage (CM) composite films, showing a significant improvement to 26.6 MPa, representing a 231.3 % increase over the control film. This study offers a promising approach for efficiently producing CNFs from raw plants. •DES2 and NaClO2 removed 99.23 % and 99.62 % of hemicellulose and lignin from elegant grass.•DES2 maintained excellent pretreatment performance after multiple cycles.•AlCl3-enhanced DES2 produced CNFs with higher crystallinity, carboxyl content, and narrower width.•CNFs remained highly dispersed in water for at least six months.•A mechanism for promoting CNF production with DES2 pretreatment was proposed.