Miscanthus × giganteus Biomass as Feedstock for Cellulose Fibers and Lignin: Extraction, Characterizations, and Potential Applications
Miscanthus × giganteus is a fast-growing and high-yielding perennial grass widely available in North America. This research investigated two pre-treatment techniques to extract cellulose fibers and lignin from miscanthus biomass and determined their potential applications. The first study investigated an ultrasound-assisted-alkali-urea (UAAU) pre-treatment for enhanced delignification of miscanthus. Sonication time, NaOH concentration, and urea concentrations were optimized using a response surface methodology. The UAAU method extracted up to 52% (w/w) cellulose fibers from miscanthus at 5% NaOH, 1.75% urea, and 20 min sonication, resulting in cellulose fibers of higher crystallinity, and thermal stability than the untreated samples. In the second study, a binary enzyme (BE) cocktail (cellulase and laccase) was investigated for the extraction of cellulose fibers from the miscanthus biomass. The cellulase-laccase cocktail extracted up to 47% (w/w) cellulose fibers, whereas the cellulase or laccase treatments alone resulted in 38% (w/w) or 36% (w/w), respectively. Paper-sheets prepared from the fibers from the BE treatment showed higher mechanical properties and water absorption capacity than those prepared from that of the single-enzyme treatments. In the third study, the extracted lignin was subjected to hydroxyethylation by ethylene carbonate, followed by esterification with propionic acid. The esterified lignin was then co-dissolved with cellulose acetate in acetone and applied as a coating on the paper-sheets. The coated paper-sheets exhibited significantly higher hydrophobicity and tensile strength, while lower water vapour transmission rate than the uncoated samples. In the fourth study, an ethyl cellulose-based nonwoven filter (NWF) was developed using a free-surface electrospinning technique. The nonwoven was loaded with silver nanoparticles (AgNPs) synthetized through reducing Ag+ with the extracted lignin. The filtration test against NaCl aerosols (≥ 0.3 µm) yielded desired performance with filtration efficiency (>99%), pressure drop (<88 Pa), and quality factor (>0.077 Pa-1) at RH (25 ± 2% and > 90%). At 60 min contact time, AgNPs loaded NWFs exhibited antiviral activity against a surrogate virus, bacteriophage Φ6, with more than 5 log10 (PFU/mL) reduction. Overall, this research shows that UAAU and BE pre-treatments could effectively extract cellulose fibers and lignin from miscanthus biomass, while the resulting fibers and lignin could be used for hydrophobic paper-sheet and antiviral mask filter applications.
Singh, S. S., Lim, L. T., & Manickavasagan, A. (2020). Ultrasound-assisted alkali-urea pre-treatment of Miscanthus?? giganteus for enhanced extraction of cellulose fiber. Carbohydrate polymers, 247, 116758. https://doi.org/10.1016/j.carbpol.2020.116758.
Singh, S. S., Lim, L. T., & Manickavasagan, A. (2022). Enhanced microfibrillation of Miscanthus?? giganteus biomass by binary-enzymes pre-treatment. Industrial Crops and Products, 177, 114537. https://doi.org/10.1016/j.indcrop.2022.114537.