Value-adding to grape waste: Green synthesis of gold nanoparticles

• Food waste can be potentially used to produce gold nanoparticles (AuNP).
• Single step green synthesis of gold nanoparticles using grape seeds, skin and stalk.
• Synthesis of gold nanoparticles within 5 min using water at room temperature.
• Gold nanoparticles of 20–25 nm were characterized by HRTEM.

In this study we report the potential use of food waste such as grape skin, stalk and seeds obtained after grape processing to produce gold nanoparticles (AuNP). The gold nanoparticles were synthesized according to the rules of green chemistry and integrating the goals of green nanotechnology. Results from the present work establish that AuNP were synthesized in a single step method using water at room temperature. The growth of AuNP was instantaneous within 5 min and was found to be highly stabilized. Thus produced AuNP were characterized using UV–Vis spectrophotometer, high resolution transmission electron microscope (HR-TEM) and energy-dispersive X-ray spectroscopy (EDX). The mean particle size for the green synthesized gold nanoparticles from grape waste ranged from 20 to 25 nm. Furthermore, a central composite design was used to determine the influences of the concentrations of catechin (0.5, 1, 1.5 mM) and HAuCl4 (0.5, 1, 1.5 mM), and of temperature (10, 25, 45 °C) on the green synthesis of AuNP. Their interactions were determined by response surface methodology (RSM).