MARIUS BUMBAC, RADU LUCIAN OLTEANU, RODICA MARIANA ION, CRISTINA MIHAELA NICOLESCU INFLUENCE OF TEMPERATURE ON THE GROWTH OF SILVER NANOPARTICLES SYNTHESIZED USING SALVIA OFFICINALIS AQUEOUS EXTRACT In this paper the silver nanoparticles (AgNPs) are synthesized by bottom-up approach using Salvia officinalis aqueous extract as reducing agent, and under such circumstances, the ultraviolet-visible (UV-Vis) spectroscopy is used to evaluate the evolution of the synthesis process, scannings in the wavelength range of 230 nm to 750 nm. The presence, position and shape of the absorption maximum in the region of 400-430 nm were monitored, and associated with AgNPs formation . Interactions of organic substrate with the generated silver nanoparticles were put into evidence by using infrared spectroscopy. The experiments were conducted at four temperatures and five different volumetric ratios of AgNPs precursors, the plant extract and silver nitrate 10 mM aqueous solutions. Conclusions on the synthesis parameters effect on process evolution were drawn. It was found that the temperature and the initial ratio of synthesis precursors influence the growth process and characteristics of the obtained AgNPs. Infrared spectra confirmed the interactions between the organic substrate and the formed AgNPs, as well as with nitrate ions present in the synthesis mixture. Thus, the position and the shape of the recorded peaks in the ranges 1500 - 1600 cm-1, 800 - 900 cm-1 and around 3400 cm-1 showed significant changes during the nanoparticles synthesis.
Keywords: silver nanoparticles green synthesis, Salvia officinalis, ultraviolet-visible and infrared spectroscopy