Production and characterization of microcrystalline cellulose from soybean hulls under optimized delignification conditions

Research into effective methods for utilising agricultural waste and producing valuable materials is a pressing issue in modern science. In this study, soybean hulls were used as the feedstock and subjected to organosolvent treatment with peroxyacetic acid prepared using two different concentrations of acetic acid (40% and 98%) with the aim of demonstrating the feasibility of using less concentrated reagents to produce a product with comparable quality characteristics. The study revealed, that MCC produced from soybean hulls using 40% acetic acid, the selected optimum liquid to solid ratio was 1:10 g/ml, resulting in a yield of 38.8%. In contrast, for MCC produced using 98% acetic acid, the selected optimum liquid to solid ratio was 1:16 g/ml, yielding 44.7%, with a delignification time of 50 min. To characterise the samples obtained, moisture content, ash content, and the content of lignin and hemicellulose were determined, and a quantitative analysis of α-, β- and γ-cellulose was carried out. Morphological, structural and dimensional features were investigated using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and particle size distribution analysis. The thermal properties of the samples were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results obtained demonstrated the feasibility of using 40% acetic acid without any significant deterioration in its quality. Thus, an optimal acid concentration of 40% yields may provide significant savings on chemical reagents, enhances environmental sustainability.