Production and characterization of structural nanocellulose from young palm fruit residues for reinforcement in bionanocomposite fabrication: from waste to nanomaterials

Abstract

Cellulose nanocrystals (CNCs), a bio-based nanoscale material derived from lignocellulosic biomass, have recently attracted significant attention as an additive to fabricate multifunctional nanocomposites owing to their physicochemical, thermomechanical, microstructural, and morphological properties and eco-friendly nature. Unlike fossil-based synthetic additives/materials (e.g., plastics), CNCs are derived from natural sources and exhibit superior mechanical strength, high crystallinity, and environmental compatibility, making them ideal green alternatives for sustainable applications. This study focuses on producing structurally pure CNCs from palm fruit waste shells (PFWSs), an agricultural residue (derived from secondary plant biomass, namely, palm trees), often discarded after collecting the edible parts. This residual mass has generally been considered organic solid waste and low-value biomass that is not suitable for use as cattle feed; rather, it is disposed of by conventional burning, leading to air, water, and soil pollution. Instead of extracting cellulose from primary plant sources (e.g., cotton and jute), which have vital industrial and agricultural roles, the target of this study is the utilization of secondary plant biomass to reduce the pressure on primary plant-derived lignocellulosic fibers. The current research addresses the gap by utilizing underexploited PFWSs as a sustainable feedstock for the extraction of high-quality CNCs. A stepwise chemical treatment was employed, including scouring (1% soap solution), alkali treatment (10% NaOH solution), bleaching (2% NaClO2 and 2% Na2S2O5 solution at pH 4.0), and acid hydrolysis with 40% H2SO4 to remove non-cellulosic components and isolate nanoscale crystalline cellulose. The extracted CNCs were characterized using FTIR-ATR spectroscopy, FE-SEM, OM, XRD, TGA, DSC, UV-vis spectroscopy, DLS, and zeta potential analysis. The results revealed high crystallinity (about 89.24%), thermal stability up to 600 °C and nanoscale morphology of the extracted CNCs. The zeta potential distribution ranged from −110 mV to +55 mV. The PFWS-derived CNCs demonstrate significant promise as a reinforcing agent in eco-friendly bionanocomposites for biomedical, packaging, and engineering applications.