Biomass origin matters: Comparative evaluation of lignocellulose nanofibers via deep eutectic solvent processing

Developing sustainable nanomaterials requires a rigorous understanding of how the origin of lignocellulosic biomass governs its composition, nanofibrillation behavior, and film performance. This study aims to elucidate these origin-dependent relationships by systematically fabricating lignocellulose nanofibers (LCNFs) from four distinct biomass sources-spent coffee grounds (SCG), mixed hardwood (MHW), acacia (AC), and rice husk (RH)-using an integrated process of sodium hydroxide pretreatment, deep eutectic solvent treatment, and mechanical nanofibrillation. Despite identical processing conditions, the resulting LCNFs exhibited markedly different chemical compositions and nanofiber morphologies, which significantly influenced their optical and mechanical properties. Cellulose/hemicellulose/lignin contents (%) of LCNFs obtained from SCG, MHW, AC, and RH were 33.7/61.6/4.0, 84.3/8.2/7.0, 80.6/5.9/12.9, and 67.7/15.7/15.6, respectively. Average fibril diameters increased with retained lignin, from 10.2 nm (SCG) to 14.1 nm (MHW), 17.2 nm (AC), and 23.6 nm (RH). Across feedstocks, film haze ranged from 54.0 % to 89.7 %, tensile strength reached 114.7 MPa (MHW), 100.8 MPa (AC), 91.1 MPa (RH), and 88.7 MPa (SCG). SCG retained a high mannan-rich hemicellulose content, yielding the finest fiber diameters but limited mechanical performance, with residual impurities affecting optical behavior. RH maintained the highest lignin content, producing coarse, non-uniform fibers with high optical haze. In contrast, MHW and AC showed superior cellulose retention, higher yields, and enhanced strength. Overall, this study establishes a predictive framework linking biomass origin to nanofibrillation and structure-property relationships, providing new insights for rational feedstock selection and process design of sustainable LCNFs.