Facile isolation of cellulose nanofibers from soybean residue

The residue of soybean after extraction of oils, proteins, and soluble polysaccharides is rich in cellulose but not well utilized. Here, we exploited the soybean residue as a raw material to isolate cellulose nanofibers via a robust chemical-mechanical process. The soybean cellulose nanofibers (SCNFs) possessed ∼50 nm diameter and micrometer-scale length. They possessed a high degree of crystallinity (75.9%), negative surface charge (-22.5 mV), and high thermal stability. The hydrogel of SCNFs represented a typical shear-thinning behavior. The viscosity of the hydrogel was influenced by pH, ionic strength, ethanol, and temperature. SCNFs could also be made into flexible and transparent films with high tensile strength, which could be a raw material for food packages. Overall, soybean residue is a cost-effective source to produce cellulose nanofibers.