Efficient conversion of moso bamboo components into glucose, lignocellulose nanofiber, and low-molecular-weight lignin through deep eutectic solvent treatment

In this study, a total utilization system consisting of deep eutectic solvent (DES) treatment, separation, acetone extraction, enzymatic saccharification, and grinder treatment was developed and evaluated to utilize the cellulose and lignin in moso bamboo effectively. The efficient removal of hemicellulose and lignin through a high reaction temperature and a long reaction time via DES treatment allowed to obtain the solid residue with a cellulose-rich residue fraction. The cellulose ratio in the solid residue was higher than 75% at 150 degrees C for 3 h. The enzyme saccharification and the preparation of the lignocellulose nanofiber through a grinder treatment were carried out to utilize the solid residue effectively. The DES treatment significantly increased the saccharification and glucose ratio, with respective maximum values of 75.5% and 0.271 g-glucose/g-bamboo were obtained at 120 degrees C for 6 h, respectively. These values are 10 times higher than those of untreated bamboo. The specific tensile strength and specific Young's modulus of lignocellulose nanofiber obtained from solid residue at 150 degrees C for 3 h were 131 MPa/(g/cm(3)) and 8.88 GPa/(g/cm(3)), respectively. These values are higher than those of commercial cellulose nanofiber (BiNFi-s), which are 110 MPa/(g/cm(3)) and 5.91 GPa/(g/cm(3)), respectively. This result shows that the DES treatment is a relatively gentle treatment and a pretreatment method capable of delignification while preserving the cellulose nanofiber length for obtaining a lignocellulose nanofiber with high mechanical strengths. In addition, since the precipitate has a lignin-rich extracted fraction from the supernatant of the DES-treated bamboo, it has low-molecular-weight lignin. Therefore, it can be used as a raw material of epoxy resin.

Automated summary

A total utilization system was developed in this study to effectively utilize cellulose and lignin in moso bamboo. Through DES treatment, hemicellulose and lignin were efficiently removed to obtain solid residue rich in cellulose, leading to the production of lignocellulose nanofiber with high mechanical strengths. The DES treatment significantly increased saccharification efficiency and glucose ratio, while the solid residue demonstrated specific tensile strength and specific Young's modulus higher than that of commercial cellulose nanofiber, showing its potential as a raw material for high-performance materials like epoxy resin.