Microwave-Assisted Extraction and Characterisation of Corn (Zea mays) Cob Waste-Derived Cellulose for Biomedical Application: Sustainable Valorisation of Food Waste

Abstract

Corn (Zea mays L, family: Poaceae) cob, a widely available agricultural by-product, holds significant potential for sustainable material development. Cellulose is a major component of corn cob. This research aims to extract and characterise cellulose obtained from corn cob. The extraction of cellulose from maize cob was conducted utilising a microwave-based green technique and thereafter characterised using FTIR, TGA, DSC, SEM, XRD, solid-state NMR, contact angle measurement, ash value, swelling index, moisture content, chemical resistance, and biodegradability tests. Cellulose was successfully extracted from corn cob and comprehensively characterised using various parameters. Organoleptic evaluation showed the cellulose to be pale yellow, hard in texture, and odourless. FTIR spectroscopy demonstrated the presence of functional groups associated with cellulose and hemicellulose, while TGA revealed a total mass loss of 57.41%, indicating the presence of thermally labile components, with 30.35% of the residue remaining stable. DSC demonstrated a significant endothermic transition, with peak at 550.48 °C, suggesting high thermal stability. SEM images showed a rough, layered, and porous surface morphology, while XRD displayed sharp peaks at 2θ ≈ 16°, 22°, and 34°, confirming a highly crystalline cellulose Iβ structure. Solid-state 13C NMR revealed distinct peaks between 60–110 ppm, showing that the sample is polysaccharide-rich crystalline material. The cellulose exhibited moderate hydrophilicity, with a mean contact angle of 69.62°. Additionally, the moisture content was found to be 8%, and the ash value was found to be 11.11%. The swelling index was found to be 328% in distilled water, 256% in phosphate buffer, and 204% in HCl, indicating high water absorption capacity. Chemical resistance was stronger in distilled water (4%) compared to phosphate buffer and acid solution (6%). Biodegradability studies revealed a 14.9% weight loss over 21 days, indicating moderate natural decomposition and highlighting its potential as a sustainable, biodegradable material. Corn cob cellulose demonstrates promising structural, thermal, and physicochemical properties, making it a sustainable, low-cost biomaterial suitable for diverse industrial and environmental applications.