Refining and application of lignin-containing cellulose nanofibers by recyclable tetrahydrofuran/water system

Lignin-containing cellulose nanofibers (LCNF) have attracted attention for their excellent properties, however traditional LCNF preparation method has problems with by-product waste and solvent recovery. Therefore, a recyclable tetrahydrofuran (THF)/water system was proposed in this study to achieve full-component refining of lignocellulose and value-added utilization of by-products. Firstly, lignocellulose was pretreated with THF/water to successfully separate pulp, lignin nanoparticles (LNPs) and polysaccharides, and ~70 % of THF was recovered. Further mechanical grinding of the pulp can obtain LCNF with enhanced stability, crystallinity and unique rheological properties, realizing the preparation of different lignocellulose-based nanomaterials. Subsequently, based on the relationship between the properties of lignin in LCNF and the film, it was proposed to introduce the by-product LNPs with active groups into LCNF to successfully enhance the film properties. Its barrier and mechanical properties were significantly improved, the tensile strength and hardness were increased to 143.26 MPa and 623.45 MPa respectively, which obtained a new high-strength encapsulation barrier film. Hence, this work not only successfully achieved the full-component refining of lignocellulose-based nanomaterials, but also realized the value-added utilization of by-products, providing a new idea for the development and application of lignocellulose-based nanomaterials.