Valorization of Silk Waste Sericin Through Zinc Oxide Nanoparticles Biosynthesis for Toxic Dye Degradation

ABSTRACT This study reports the development of an environmentally benign photocatalyst through the sericin‐mediated green synthesis of zinc oxide nanoparticles (SS‐ZnO NPs), utilizing waste silk byproduct sericin. Sericin acted as both a reducing and stabilizing agent. The synthesized SS‐ZnO NPs were comprehensively characterized using UV–vis spectroscopy, x‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive x‐ray spectroscopy, dynamic light scattering, and zeta potential analysis. The absorption peak at 340.0 nm validated the successful formation of SS‐ZnO NPs. The SS‐ZnO NPs exhibited a hexagonal wurtzite crystal structure with an average crystallite size of 82.66 nm. SEM analysis revealed a distinctive flower‐like morphology, and the average zeta potential was measured at +8.82 mV, indicating moderate colloidal stability. Photocatalytic performance was evaluated through the degradation of methyl orange (MO) dye. The highest degradation efficiency was observed at a dye concentration of 10 ppm, pH 4, and catalyst dosage of 0.2 g L −1 , yielding a maximum degradation rate constant of 0.0432 min −1 . The acidic conditions significantly favor the photocatalytic process compared to neutral and alkaline environments. The catalyst's stability after the first cycle of MO degradation was also assessed by conductivity and XRD measurements. Thus, sericin is a potential chemical species for synthesize effective ZnO NPs photocatalyst.