Synthesis and Characterization of Bi Methalic Nanoparticles (Ag-Ni) from the Leaf Extract of Vernonia Amiygdolina with the Evaluation of Photocatalytic Degradation of Methylene Blue Dye

Nanoparticles are increasingly gaining scientific attention due to their wide range of applications, particularly in photocatalysis, as well as the growing interest in their synthesis. In this study, the photocatalytic degradation of methylene blue (MB) dye was examined under UV light in a photo-reactor with a wavelength of 350 nm, utilizing an eco-friendly and non-toxic method. Silver-nickel bimetallic nanoparticles were synthesized using Vernonia amygdalina leaf extract and characterized through SEM, UV-Vis, XRD, and FT-IR techniques. The UV-Vis spectrum of the nanoparticles showed a maximum absorbance at 300 nm, attributed to the surface plasmon resonance and the bio-reduction and capping agent present in the leaf extract. FTIR analysis indicated the presence of O-H stretching, likely from hydroxyl alcohol and phenols at 3584.73 cm-1, C-H stretching of alkanes at 2852 cm-1, C=C stretching of alkenes at 1651 cm-1, and an N-O symmetry stretch of nitro compounds at 1542 cm-1. SEM images revealed that the particles have a relatively uniform shape, with even distribution and homogeneity. XRD analysis showed peaks at 2θ values of 2.16°, 34.53°, 44.08°, and 64.32°, corresponding to the (110), (111), (210), and (311) planes, respectively. This confirmed a Face-Centered Cubic (FCC) structure, with an average crystallite size of 29.97 nm, calculated using the Scherrer equation. The photocatalytic degradation of methylene blue was studied under varying conditions through a batch adsorption experiment. The bimetallic nanoparticles exhibited high efficiency in dye degradation, achieving a maximum degradation rate of 98.50%. Kinetic studies followed a pseudo- first-order model (R2 = 0.9991). Thermodynamic calculations revealed a negative ΔGo and positive ΔHo, indicating that the photocatalytic degradation of MB dye by the nanoparticles is a spontaneous and endothermic process. The nanocatalyst's maximum photocatalytic degradation capacity was found to be 0.4 mg/g, representing a 98.50% degradation efficiency. These findings suggest that the synthesized nanocatalyst is an effective absorbent for the photocatalytic degradation of MB dye in aqueous solutions.