Eco-friendly fabrication of lignin nanoparticles with tuneable size and UV-attenuation using choline chloride lactic
Aisha Saleem1, Xuanjia Yu1, Lingzhi Huang1
1Liaoning Key Lab of Lignocellulose Chemistry and Biomaterials, The Liaoning Province Key Laboratory of Paper and Pulp Engineering, The Key Laboratory of High Value Utilization of Botanical Resources of China Light Industry, College of Light Industry and Chemical Engineering, Dalian Polytechnic University, Dalian, Liaoning, 116034, China.
Abstract:
Lignin nanoparticles (LNPs) represent a promising class of sustainable nanomaterials derived from abundant industrial lignin. Herein, we report a green and tunable strategy for fabricating LNPs from softwood kraft lignin via antisolvent nanoprecipitation using a choline chloride-lactic acid (ChCl:LA) deep eutectic solvent (DES). By systematically varying the DES molar ratio (1:5, 1:10, and 1:15) and processing temperature (60-100 °C), the influence of processing severity on nanoparticle formation, size distribution, colloidal stability, and yield was elucidated. The intermediate ratio (1:10) at 80 °C emerged as the optimal condition, yielding spherical, uniform LNPs with a hydrodynamic diameter of ∼255 nm, excellent colloidal stability (PDI = 0.22, ζ-potential = -27.7 mV), and a dry-state size of ∼115 nm. Notably, high gravimetric yields (85-92%) were obtained across all conditions, indicating efficient lignin recovery. Structural characterization demonstrated that the optimal performance was attributed to the preservation of β-O-4 linkages and limited condensation, which facilitated controlled nanoprecipitation. The resulting LNPs exhibited strong broadband UV absorption with high visible-light transparency, underscoring their potential for UV-protective applications. This work establishes ChCl:LA DES as an effective and environmentally benign platform for producing lignin nanoparticles with tunable properties, supporting the sustainable valorization of technical lignin.
