Insight into the performance of lignin-containing cellulose nanofibers (LCNFs) via lignin content regulation by p-toluenesulfonic acid delignification

Residual lignin affects the physical and chemical performance of lignin-containing cellulose nanofibers (LCNFs). In this work, LCNFs were prepared from sugarcane bagasse powder (SBP) through p-toluenesulfonic acid (p-TsOH) hydrolysis and the subsequent homogenization treatment. By adjusting the concentration of p-TsOH and hydrolysis temperature, LCNFs with lignin content of 4.69–17.53% were obtained, and the effects of lignin content on the chemical structure, crystallinity, size, hydrophobicity and thermal stability of LCNFs were systematically studied. With the increase of lignin content, the diameters and average water contact angles of LCNFs were increased (from 169.65 to 781.56 nm and 39.74–86.16°, respectively), while the crystallinities were decreased. The thermal stabilities of LCNFs were decided both by lignin content and the crystallinity. The by-product lignin nanoparticles (LNPs) with an average diameter of 50–500 nm were generated with LCNFs, further improving the resource utilization value of SBP. This study provides theoretical and experimental basis for the subsequent processing of films with different hydrophobic properties and materials with higher mechanical properties and thermal stability.Graphical abstract