Tailoring nano lignin properties for pickering emulsions: A study on biomass, pretreatment, and solvent effect

Lignocellulosic biomass is the most abundant renewable resource for sustainable materials and lignin has significant potential for advancing bio-based products. This work focused on the effect of biomass source and pretreatment technique on the characteristics of nanolignin particles (NLPs) and their potential to stabilise Pickering emulsions. Macrolignin particles (MLPs) from oil palm residues and beech biomass were extracted using organosolv or soda pretreatment. The MLPs were characterized by measurements such as surface contact angle, NMR, size exclusion chromatography, and antioxidant properties, then converted into NLP suspensions via antisolvent precipitation. The generated NLPs had diameters that ranged from 104.7 to 199.6 nm and negative zeta potentials (−20.1 to −28.7 mV). All the NLP suspensions showed negative zeta potential values, indicating colloidal stability, with OPFL-OL exhibiting the highest surface charge. The NLPs stabilized oil-in-water (o/w) Pickering emulsions with isopropyl myristate, resulting in droplets ranging from 3 to 7 microns and maintained stability for 30 days with negligible variations in the creaming index. Structure-property correlations demonstrated that lignin molecular features influence nanoparticle production and emulsification behaviour, with B-OL and OPEFB-SP demonstrating the best results.