Fast and Eco–friendly Microwave-Assisted Synthesis of Silver Nanoparticles using Rosemary Essential Oil as Renewable Reducing Agent

A green and fast methodology was developed to synthesize silver nanoparticlesusing rosemary essential oil (EO) as a renewable reducing agent. The synthesis process was microwave (MW) assisted, using acoaxialdipole antenna immersed into the reaction medium. This configuration was used to promote both: i) rosemary EO extraction by hydrodistillation, and ii) silver nanoparticle synthesis in an aqueous solution at atmosphericpressure. The effect of two different silver salt substrates and the time reaction on the morphology of the silver nanoparticles was explored. The coaxial microwave assisted hydrodistillation of rosemary yields 0.4%(w/w) in 30 min and contains ethers (17%), ketones (50%) and alcohols (15%). Silver nanoparticles with a tuneable particle size (from 7 to 18 nm) and morphology(from spherical to round-like shapes)were obtained in reaction times ranging from 2to 30 min. The nanoparticle formation was followed b yU V-vis spectroscopy and SEM imaging.