Photodegradation of lignin biowaste catalyzed by biosynthesized zinc oxide nanoparticles using the leaf extract of Aristotelia chilensis

• Biogenic ZnO–B nanoparticles achieved up to 90.57% lignin degradation. • First study evaluating biogenic ZnO for photocatalytic lignin degradation. • Photocatalytic lignin conversion into high-value chemicals with diverse uses. This study evaluated the photocatalytic activity of zinc oxide nanoparticles (ZnO-B) synthesized using a leaf extract of Aristotelia chilensis and the effect of calcination at different temperatures (400, 600, and 800 °C) on their properties and performance. The photocatalytic degradation of lignin was compared among biogenic ZnO-B, chemically synthesized ZnO (ZnO–Ch), and commercial ZnO (ZnO–C). The lignin degradation rates after 24 h were ZnO–B_400 (60.8%), ZnO–B_600 (90.57%), ZnO–B_800 (27.83%), ZnO–Ch (23.2%), and ZnO–C (80.7%). The nanoparticles were characterized by TEM, XRD, FTIR, and UV–vis spectroscopy. The physicochemical properties and photocatalytic efficiency of ZnO–B were significantly influenced by calcination temperature, with ZnO–B_600 demonstrating superior photocatalytic activity under UV-A and simulated sunlight. GC–MS analysis of lignin degradation products revealed the transformation of lignin into high-value chemicals, including 2,3-hexanediol, 1,2-benzenedicarboxylic acid diethyl ester, phthalic acid cyclobutyl isobutyl ester, 2-(1-oxopropyl)-benzoic acid, and 4-hydroxy-2-butanone. These findings highlight the potential of biogenic ZnO-B nanoparticles in photocatalytic processes for the valorization of Kraft lignin into value-added compounds of interest to the chemical, cosmetic, and pharmaceutical industries.