Clean and high-throughput production of silver nanoparticles mediated by soy protein via solid state synthesis

A one-pot method that uses solid-state reactions at ambient temperature is proposed for high throughput and green synthesis of silver nanoparticles. Nano-sized silver metal was synthesized in less than 5 min by simply eco-grinding silver nitrate, soy protein isolate powder and sodium hydroxide pellets, in the absence of any solvent or organic protector. The loading and reduction efficiency of the reaction was readily controlled by adjusting the soy protein isolate/silver nitrate molar ratio and sodium hydroxide loading. The formation of nanostructured silver was elucidated by using complementary spectroscopy and imaging techniques, including ultra-violet spectroscopy, Transmission and Field Emission Scanning Electron microscopy with Energy Dispersive X-ray, Dynamic Light Scattering, X-Ray Diffraction, Fourier Transform infra-red spectroscopy and Surface Chemical Composition. The reducing effect of soy protein isolate to convert silver ions into silver nanoparticles in high yields was demonstrated, with no evidence of aggregation or phase separation. The results indicate excellent prospects toward cleaner and scale-up synthesis of silver nanoparticles.