Design and characterization of an almond shell-based nanocellulose/chitosan nanocomposite as a bio-derived modifier

Athraa Basheer Radhi

doi:10.64943/ljacs.2026.010210

Authors

Athraa Basheer Radhi Department of Laboratory and Clinical Sciences, College of Pharmacy, University of Anbar, Anbar, Iraq https://orcid.org/0009-0007-8858-2197

DOI:

https://doi.org/10.64943/ljacs.2026.010210

Keywords:

sustainable agriculture, Almond shell waste, TEMPO oxidation, environmental applications, TPP nanoparticles

Abstract

The increasing production of agroindustrial residues demands sustainable strategies that minimize waste and obtain high value materials. Cellulose nanocrystals (CNCs) were obtained from almond shell waste and integrated into a fully bio-based nanocomposite with chitosan and folic acid by means of aqueous low-impact processing. Almond shells were purified via alkaline treatment and bleaching, hydrolyzed with sulfuric acid to obtain the CNCs, and then oxidized using a TEMPO/NaBr/NaClO system to introduce carboxylate groups on the surface. Chitosan nanoparticles were prepared by ionic gelation with tripolyphosphate, and a model bioactive compound, folic acid, was loaded in hybrid CNC/chitosan dispersions.
Scanning electron microscopy (field emission) revealed a porous lamellar structure with nanometric cellulose sheets (80-250 nm thick) embedded in a continuous chitosan-rich matrix providing a scaffold of high surface area. X-ray diffraction confirmed that the cellulose I polymorph and nanocrystalline character were maintained, and a moderate decrease in Segal crystallinity index was noticed upon composite formation, explained by the dilution effect from amorphous chitosan and folate, instead of lattice disruption. Estimated crystallite sizes using the Scherrer equation were in the range 10-15 nm. ATR FTIR spectroscopy evidenced extensive hydrogen bonding and electrostatic interactions between CNC, chitosan and folic acid, and successful folate incorporation was confirmed by diagnostic aromatic/carbonyl bands. Zeta potential measurements showed a low negative surface charge at near-neutral pH

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