Facile Green Synthesis and Photocatalytic Efficiency of Ag-Zn Bimetallic Nanoparticles for Degradation of Methylene Blue
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Abstract
A sustainable plant-mediated approach was adopted for the synthesis of Ag–Zn bimetallic nanoparticles (BMNPs) utilizing Achyranthes aspera leaf extract as an eco-friendly reducing and surface-stabilizing agent. The successful formation of nanoparticles was evidenced by UV-Visible spectroscopy through distinct surface plasmon resonance features, confirming their nanoscale nature. Functional group analysis by FTIR indicated the role of phytochemical constituents in the reduction and stabilization of the bimetallic system. Elemental composition and morphological investigations using EDX and FESEM revealed that the synthesized Ag–Zn BMNPs possess predominantly spherical morphology and particle sizes ranging from 10 to 70 nm. The photocatalytic activity of the prepared nanoparticles was examined under natural sunlight irradiation for the degradation of methylene blue (MB), a representative organic dye contaminant. The influence of key operational parameters, including irradiation time, dye concentration, solution pH, and catalyst loading, was systematically assessed. Maximum degradation efficiency of 86.85% was achieved at neutral pH (7), with a catalyst dosage of 40 mg, an initial MB concentration of 5 ppm, and an exposure time of 180 min. The findings demonstrate that green-synthesized Ag–Zn bimetallic nanoparticles are promising photocatalysts for environmentally sustainable wastewater treatment applications.