Sustainable Green Synthesis of Silver Nanoparticles From Roasted Hazelnut Shell Waste: Biological and Photocatalytic Applications

In this study, silver nanoparticles (AgNPs) were synthesized through a green chemistry approach using roasted hazelnut inner shells, an abundant agricultural byproduct. The hazelnut shell‐derived AgNPs (HIS‐AgNPs) were characterized by UV‐visible spectroscopy, FT‐IR, SEM, TEM, XRD and zeta potential. UV‐vis revealed a surface plasmon resonance peak at 436 nm, while SEM showed spherical particles of 67.8 ± 25.7 nm in size. HIS‐AgNPs exhibited antimicrobial activity against Staphylococcus aureus , Pseudomonas aeruginosa , and Candida albicans , with inhibition zones of 10, 11, and 15 mm and MIC values of 250, 125, and 62.5 µg mL −1 , respectively. They also strongly inhibited acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), with IC 5 0 values of 4.1 and 2.9 µg mL −1 , suggesting relevance for neurodegenerative disorders. In addition, HIS‐AgNPs achieved > 90% photocatalytic degradation of methylene blue under sunlight within 3 h, following pseudo‐first‐order kinetics. Overall, this work demonstrates the sustainable conversion of hazelnut waste into multifunctional AgNPs with promising biomedical and environmental applications.