Synthesis of highly crystalline cellulose nanocrystals from corncob agricultural waste

Abstract Cellulose nanocrystals (CNCs) were extracted from corncob agricultural waste via sulfuric acid hydrolysis, followed by separation using centrifugation, and dialysis to achieve maximum yield.The maximum yield (41.8%) of cellulose nanocrystal was found at the parameter interaction of 65 wt.% sulfuric acid concentration,45 °C reaction temperature, and 60 min of hydrolysis time. Process parameter optimization using response surface methodology identified optimal conditions of 61.66 wt% H₂SO₄, a reaction temperature of 45 °C, and a hydrolysis time of 59.92 min, yielding a validated experimental yield of 40.94 ± 0.25%, which closely agreed with the predicted yield of 41.74%. Fourier transform infrared spectroscopy confirmed the chemical structure of cellulose nanocrystals prepared by sulfuric acid hydrolysis of isolated cellulose whereas transmission electron microscopy revealed uniform needle-like morphology with an average length of 170.3 nm. Notably, X-ray diffraction demonstrated a high crystallinity index of 79.3% for the isolated CNCs, marking a distinct increase over the isolated cellulose precursor (76.4%) and outperforming typical agro-waste-derived CNCs reported in literature (65–74%). Thermogravimetric analysis indicated superior thermal stability, with a peak degradation temperature reaching 327 °C substantially higher than both the raw corncob and extracted cellulose, as well as conventional acid-hydrolyzed bio-nanocellulose benchmarks (220–280 °C). These findings highlight corncob as a high-performance precursor for thermally robust, highly crystalline nanocellulose suitable for demanding biocomposite applications.