Eco-Friendly Cellulose-Inspired Nanoparticles from Agro-Waste vs. Chitin Nanoparticles: Dual Functionality in Metal Adsorption and Optical Applications

Abstract This study evaluates two biopolymer-based nanoparticles derived from Giant Reed (cellulose) and chitin as sustainable precursors for dual applications: heavy metal adsorption and liquid crystal formation. The novelty lies in upcycling Giant Reed-based cellulose nanoparticles (Cel-NPs) as metal adsorbents and reusing their metal-chelated forms as effective liquid crystal biopolymers, achieving a zero-waste strategy. The nanoparticles were characterized using Transmission Electron Microscopy (TEM), Attenuated Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-ray Diffraction (XRD), and Polarized Optical Microscopy (POM) to evaluate their morphology, functional groups, crystallinity, and liquid crystalline behavior. Comparative analysis between Cel-NPs and chitin nanoparticles (Ch-NPs), including their esterified derivatives (ECel-NPs and ECh-NPs), was conducted. Metal chelation studies showed Cel-NPs exhibited higher affinities for Cu²⁺, Zn²⁺, and Cd ²⁺ (29.01 ± 1.1, 30.33 ± 1.2, and 20.69 ± 0.8 mg/g, respectively) compared to Ch-NPs (24.96 ± 0.99, 29.78 ± 1.2, and 17.34 ± 0.7 mg/g). Structural modifications metal loading and esterification with decanoyl chloride enhanced the crystallinity indices of the nanoparticles and significantly improved their liquid crystalline behavior. Notably, the critical concentration for liquid crystal formation dropped from 1 wt% to 0.5 wt% for modified Cel-NPs, and from 5 wt% to 0.5 wt% for modified Ch-NPs, highlighting their potential in advanced biofunctional materials. *Corresponding information: A. H. Basta. email: [email protected] , and [email protected] .