Mangifera indica flower extract mediated biogenic green gold nanoparticles: Efficient nanocatalyst for reduction of 4‐nitrophenol

A facile, one‐step and greener route for the synthesis of gold nanoparticles (AuNPs) was developed in pursuit of an eco‐friendly alternative via green synthesis of gold nano‐materials. Mangifera indica (mango) is one of the most popular fruits and key herb in the Ayurvedic and ethno‐veterinary‐medical systems for several thousand years. We report here for the first time the AuNPs synthesis from auric chloride salt using aqueous extract of M. indica flowers as reducing and stabilizing agent. The biosynthesis process was fast with most of the AuNPs forming within 20 minutes and the reaction‐kinetics reaching a plateau in just an hour. The AuNPs were characterized by UV‐Vis absorption spectroscopy, TEM, high‐resolution transmission electron microscopy (HRTEM), energy dispersive X‐ray (EDX) spectroscopy, nanoparticle tracking analysis (NTA), dynamic light scattering (DLS) measurements and Fourier‐transform infrared (FTIR) spectroscopy, which confirmed the bio‐reduction of gold ions. The bio‐reduced AuNPs were mostly spherical with a dimension range nearer to 10–60 nm by TEM and a modal size of 32 nm by NTA. These AuNPs exhibited excellent nanocatalysis in the reduction of 4‐nitrophenol to 4‐aminophenol by NaBH4 in aqueous phase. These biogenic gold nanoparticles could be useful for remediation of waste‐waters and effluents containing nitroarene, such as 4‐Nitrophenol. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 283–294, 2018