Green production of size-tunable cellulose nanoparticles from corn cobs

This study reports an eco-friendly method for synthesizing size-controlled regenerated cellulose nanoparticles from corn cobs. The process involved deep eutectic solvent (DES) extraction and NaOH/glycerol dissolution, and subsequent nanoprecipitation. Compositional analysis using the Chesson method confirmed that DES treatment successfully enriched the cellulose fraction compared to raw corn cobs, demonstrating its effectiveness in purification. FTIR analysis further verified cellulose purification, evidenced by the disappearance of hemicellulose-associated C=O peaks (1723-1724 cm−1), and reduced aromatic lignin peaks (1601−1514 cm−1). Characteristic cellulose peaks at 1030 cm−1 and 897 cm−1 were retained, while C–H stretching (2900−2800 cm−1) and C–O–C bands (1200−1000 cm−1) confirmed structural integrity. Particle size analysis revealed that extracted cellulose had an average size of 2303.4 nm. Regeneration with 4% NaOH/glycerol, followed by ultrasonication and precipitation in 3M HCl, yielded nanoparticles with markedly reduced sizes: 202 nm without ultrasonication and 180.8 nm after 15 min ultrasonication, corresponding to a 92% size reduction. Ultrasonication and glycerol played crucial roles in achieving uniform dispersion and minimizing aggregation. This approach demonstrates the potential of corn cobs as a sustainable cellulose source and offers a green pathway for producing nano-sized cellulose for applications in biomaterials, nanocomposites, and drug delivery.