A comprehensive investigation on the production and characterization of cellulose nanocrystals derived from pulps and shells: Argania spinosa bio-residues as a case study

• First-time extraction of CNCs from unexplored Argan pulp waste • CNC-Shell showed exceptional crystallinity index of 88.67% • CNCs exhibited distinct spherical morphology with a diameter of less than 37 nm • High colloidal stability confirmed by Zeta potential values below -28 mV • Produced CNCs offer a sustainable alternative to fossil-based materials This study provides for the first time the extraction of cellulose nanocrystals (CNCs) and cellulose microfibers (CMFs) from Argania spinosa’s pulp, and a detailed comparative analysis of CMFs and CNCs extracted from Argan pulp (AP) and shell (AS), revealing significant differences in their properties depending on the source (pulp or shell). Complementary characterization techniques scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Zeta potential, and thermogravimetric analysis (TGA) were employed to investigate their microstructural, chemical, structural, colloidal, and thermal properties. SEM/TEM results showed notable microstructures, CNC-AS and CNC-AP exhibited a spherical and a quasi-spherical shape, respectively. Their particles size exhibited an average diameter of 37.8 ± 0.8 nm and 8.1 ± 0.95 nm, respectively. The FTIR spectroscopy confirmed the effective removal of non-cellulosic components, especially for shell-derived CNCs. The XRD analysis confirmed the highest crystallinity index of CNC-AS (88.0 ± 0.7 %) compared to CNC-AP (63.2 ± 1.3 %). Zeta potential measurements showed a high negative surface charge of −28.68 ± 3.82 mV and −28.55 ± 2.12 mV, for both CNC-AS and CNC-AP, respectively. This makes them ideal for stable dispersions in nanocomposites systems. TGA/DTG analysis demonstrated that CNCs possess superior thermal stability compared to CMFs. This research highlights the conversion of Argan wastes into high-value CNCs and CMFs, providing a sustainable alternative to fossil-based materials and enabling innovative applications in nanotechnology.