In this study, a green, environmentally friendly method for rapid cellulose nanofribril (CNF) preparation with a significant cost advantage was developed. Pretreatment with a deep eutectic solvent (DES) synthesized from oxalic acid dihydrate and choline chloride (ChCl-O) was combined with various mechanical treatment methods to produce okara CNFs from agricultural waste, with different diameter distributions. The results showed that high-speed stirring produced CNFs with an average diameter of 27 nm. This method was advantageous because it consumed about 94% less energy than traditional high-pressure homogenization method. The DES recovery rate was more than 90%, and DES served as a highly effective treatment, indicating that DES pretreatment is an economical, convenient, and effective strategy for okara CNF preparation.

Cellulose nanofiber (CNF) was isolated from Okara using deep eutectic solvent (DES) with high-speed stirring. The composite hydrogels obtained by using different proportions of CNF and sodium alginate (SA) had different properties. The CNF/SA composite hydrogels were analyzed using Fourier transform infrared spectroscopy and scanning electron microscopy and tested for compression properties, rheological properties, water content, and swelling degree. Physical crosslinking between SA and Ca²⁺, and different degrees of hydrogen bond formation between SA and CNF were observed. The CNF/SA composite hydrogel have great potential as reinforcements in eco-friendly composite hydrogels for diverse applications.

To reduce the adverse effects of non-cellulose materials on subsequent homogenization, the effects of a high-pressure homogenization treatment on the structure and properties of cellulose nanofibers (CNF) prepared by acid treatment of soybean residue were studied. The effects of the number of homogenization step on the microfibrillation degree, crystalline structure and mechanical properties of the soybean residue were analyzed by SEM, FT-IR, XRD, TG and DTG. The results showed that an increase in the number of homogenization steps led to an increase in the degree of microfibrillation, a more uniform distribution of the CNF diameter, and an increase in the crystallinity of CNF. However, but when the number of homogenization steps exceeded 15, the rate of change decreased, and the crystallinity of CNF decreased. As the number of homogenization steps increased, the average degree of polymerization and average molecular weight of CNF decreased continuously, and after 15 homogenization steps, their rate of change also decreased. Therefore, 15 steps of high-pressure homogenization represented a suitable number of steps to prepare the soybean residue CNF with an average diameter of 15 nm.

In this study, soybean residues were treated with HCl and soybean residue cellulose was extracted, which was used to prepare cellulose nanofiber (CNF) using the high-pressure homogenization method. The maximum yield of CNF, the reaction temperature, reaction time, and HCl concentration were optimized. The optimum HCl concentration for acid treatment was 6%, the reaction time was 60 min, the reaction temperature was 80℃, and the maximum yield of soybean residue cellulose was 78.8%. The different CNF films were then prepared; the color, mechanical property, and light transmittance of the CNF films were studied. Compared to the properties of the CNF film prepared with the soybean residue cellulose by high-pressure homogenization 15 times (HGT-15 film), the mechanical properties of the CNF film with soybean residue cellulose by decolorizing treatment decreased, but the light transmittance increased. The film prepared by adding HGT-15 CNF to whey protein was investigated for its mechanical property, light transmittance, and solubility. Unlike the pure whey protein film, addition of 2.0% CNF to the whey protein enhanced the mechanical property and water vapor transmission rate (WVT) of the film. With the increase in CNF content, the solubility of the whey protein film decreased, and then stabilized.