Microwave-assisted facile synthesis of silver nanoparticles in aqueous medium and investigation of their catalytic and antibacterial activities

•The method is simple, fast, economic and eco-friendly.•This synthetic route uses non-toxic hexamine as reducing agent and easily renewable agar as the stabilizer.•Bulk synthesis of highly stable spherical silver nanoparticles can be done by this method.•The synthesized silver nanoparticles show excellent catalytic activity for the reduction of methyl orange.•The nanoparticles are effective against Gram positive and Gram negative bacteria.

A simple, fast, efficient and cost effective synthetic strategy based on microwave irradiation is described for the preparation of silver nanoparticles in aqueous medium using hexamine as the reducing agent and agar as the stabilizer. The formation of nanoparticles is confirmed using UV-vis., XRD, EDX, and HR-TEM analysis. TEM images suggest that the nanoparticles are of spherical shape with an average diameter of 10.16 nm. The agar stabilized silver nanoparticles show excellent catalytic activity for the reduction of methyl orange in the presence of NaBH4 in aqueous medium. The reaction follows pseudo-first order kinetics, and the reaction rate increases with increase in amount of the catalyst. The synthesized silver nanoparticles are expected to be promising material for the application in environmental protection. They also show very good antibacterial activity against Staphylococcus aureus (Gram positive) and Salmonella typhi (Gram negative).

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