Preparation of Lignocellulosic Nanofibrils Directly from Corn Straw Applied for the Stabilization of Pickering Emulsions

This study proposes a straightforward, cost-effective, and environmentally benign approach for the pretreatment of corn straw using alkaline cationization, followed by mechanical defibrillation to yield lignocellulosic nanofibrils (LCNF) as stabilizers of Pickering emulsions. Two distinct types of LCNFs (designated as LCNF-0.07 and LCNF-0.14) are obtained and characterized by a range of techniques. The charge density of these LCNFs is found to be 0.07 and 0.14 meq g⁻¹, respectively. The findings demonstrate that continuous alkaline cationic pretreatment can effectively remove most hemicelluloses and lignin, thereby loosening the structure of the fiber cell wall and facilitating the subsequent nanofibrillation of the resulting cellulose-rich solid (lignocellulose). The diameters of individual LCNFs are typically in the range of 20–30 nm, exhibiting high aspect ratios, a fine web-like structure, high dispersion stability, and good thermal stability. Under optimal conditions, long-term emulsion stabilization is achieved with LCNF-0.14 at concentrations as low as 0.7 wt% and with a low oil fraction of up to 10%. This can be attributed to the Pickering stabilization achieved by irreversible adsorption of the LCNF at the oil–water interface (as evidenced by fluorescent microscopy) and subsequent formation of an interdroplet LCNF network in the continuous phase (as verified by scanning electron microscope images).