Tunning antisolvent precipitation for the synthesis of lignin nanoparticles using lignin extracted from different agro-industrial wastes.

Lignin nanoparticles (LNPs) show great potential in UV-protectants, drugs carriers, encapsulation, supercapacitors, and others. This study proposes the development of an optimised LNP synthesis method by antisolvent precipitation, using lignin from persimmon tree pruning waste, green coconut waste, and sugarcane bagasse. The best synthesis conditions were determined evaluating the chemical composition and the physicochemical properties of the LNPs, by varying the antisolvent addition rate, initial lignin concentration and antisolvent pH. Optimal precipitation conditions - 250 μL·s, 5 mg·mL of lignin, pH 7.0 (antisolvent), 250 μL·s adding antisolvent - converted the persimmon, coconut, and the sugarcane lignin into nanometric structures (Ø = 130-192 nm), with a spherical morphology, which were stable during storage at 5 °C for 90 days. Particle formation did not cause significant changes in the chemical composition of the lignins, and regardless of the plant origin, the LNPs showed higher UV absorption and thermal stability than the original corresponding lignins.