Rice Husk-Derived Engineered Nanocellulose at Nano-Geo Interfaces for Mitigating Anthropogenic Heavy Metal...

Rice husk, an agricultural waste, was employed as a raw material to extract cellulose using an optimized chemical and physical treatment approach, offering a sustainable solution for value-added applications. The extraction process included pre-treatment to eliminate waxy impurities, oxidative treatment with 4% H₂O₂, hydrolysis using 70% HNO₃, and ultrasonic treatment to isolate nanoscale fibrils. Characterization of the extracted cellulose was conducted using Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), particle size analysis, Gel Permeation Chromatography (GPC), X-ray Diffraction (XRD), and Thermogravimetric Analysis (TGA). FT-IR analysis confirmed the removal of non-cellulosic components and the presence of β-(1 → 4)-glycosidic linkages, while SEM revealed fibrils with reduced diameters ranging from 800 to 900 nm. Particle size analysis indicated a mono-dispersed nanoscale distribution. XRD analysis demonstrated crystalline cellulose-I, with the crystallinity index calculated at 70 ± 3%, attributed to the effective elimination of lignin and hemicellulose. TGA showed a decomposition temperature of 333 °C with minimal residue, confirming the high thermal stability and purity of the product. GPC analysis indicated a high molecular weight and narrow polydispersity index, further verifying the superior quality of the extracted cellulose. Batch adsorption experiments further demonstrated the effectiveness of rice husk-derived nanocellulose in immobilizing Pb²⁺ ions, highlighting its potential for mitigating anthropogenic metal contamination in environmental systems. The combination of high crystallinity, thermal stability, and nanoscale morphology makes the extracted cellulose highly suitable for advanced applications, such as biocomposite nanofibers in packaging. This study underscores the potential of converting agricultural waste into high-value materials, aligning with sustainable development goals and promoting eco-friendly industrial applications.