Integrated acetosolv–alkaline processing for cellulose extraction from corn cobs

Abstract: Agricultural residues offer promise as a sustainable feedstock for making high-value natural polymers. However, such sources and, unfortunately, environmentally friendly methods to produce functional cellulose are still limited. In this study, we present a simple and scalable process to produce high-quality cellulose from corn cobs, an underused agricultural leftover from corn production. Integrating acetosolv fractionation of the corn cobs followed by alkaline treatment of the crude cellulose pulp yields amorphous cellulose with high purity and at high yields (~75% based on crude cellulose). When compared to commercial microcrystalline cellulose (MCC), the corn cob–derived cellulose (C3) exhibited nearly twice the surface area and pore volume, along with a lower water contact angle, indicating greater hydrophilicity. Remarkably, C3 had roughly four times the water-holding capacity and twice the oil-holding capacity of MCC. Helium pycnometry revealed a higher density for C3 compared to MCC, while low-field NMR data indicated similar water relaxation populations for MCC and C3. X-ray diffraction analysis of C3 showed about a 50% reduction in crystalline index, consistent with the formation of an amorphous structure confirmed by solid-state 13C NMR. FTIR and NMR analyses detected no C=C or C=O signals, indicating effective lignin removal. These attributes of C3 are attractive to make functional materials and dietary fibers with significantly more value than the corn cobs. Such product diversification has the potential to improve the economic and environmental profiles of corn-based biorefineries.