Optimization of biogenic silver particle synthesis for methylene blue degradation

This study presents an optimization of the sustainable synthesis of silver particles (AgPs) derived from hazelnut leaves employing a full factorial design. Four synthesis parameters were systematically evaluated at two levels: the water-to-leaf ratio (LW), extract-to-AgNO₃ ratio (EAg), AgNO₃ molarity (Mol), and plant leaf size (LS). Statistical analysis revealed that LW and the interaction between EAg and Mol are significant factors influencing the synthesis yield of AgPs. In contrast, Mol, LS and the EAg × Mol interaction were determined to be the key factors affecting the efficiency of dye degradation. The optimized AgPs demonstrated enhanced degradation kinetics, following a pseudo-second-order model (k ₂ = 67 × 10⁻³ mg g⁻¹ min⁻¹, R² = 0.99) and fitting well with Langmuir-Hinshelwood kinetics (k _app = 5.9 min⁻¹, R² = 0.88). Scanning electron microscopy with energy-dispersive X-ray (EDX) analysis and particle size analysis confirmed that AgPs optimized for dye degradation possessed smaller particle sizes and larger surface areas (0.201 m² g^-1 versus 0.113 m² g^-1), which contributed to improved catalytic performance. EDX analysis revealed a higher carbon and oxygen content in these AgPs, indicating the presence of surface functional groups that promote adsorption. Although the overall degradation efficiency of AgPs was slightly lower than that of certain other nanoparticle systems, their kinetic performance was comparable. This study emphasizes the critical role of synthesis optimization in enhancing catalytic activity and highlights AgPs as a promising eco-friendly catalyst for wastewater treatment applications.