Arash Ghazitabar - Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Hafez Ave., Tehran, Iran
Malek Naderi - Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Hafez Ave., Tehran, Iran

Copper anode slime is a rich source of gold metal (approximately 1000 ppm). Many researchers tend to use slime as a secondary source due to its rich potential of gold extract. This study investigates a novel method for synthesis of silica@gold core-shell (SGP) from copper anode slime. Silica nanoparticles are used as cores and their surface are coated by cationic gold-thiourea complex which are obtained from copper anode slime. In comparison with the common method of silica-gold nanoshell preparation using pure gold, this novel method is more controllable. The electrostatic interaction between negatively charged silica surface and positively charged cationic gold complex leads to formation of core-shell nanostructures. Monodisperse silica nanoparticles were synthesized by the well-known Stober protocol. By controlling pH value and reaction time, gold precursor was homogeneously deposited onto silica particles. The synthesized SGP particles are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and wavelength dispersive spectroscopy (WDS), Fourier transform infrared spectroscopy (FTIR). SEM and TEM images demonstrate that the size of silica particles are about 100 nm and then the size of synthesized SGP particles increase to 130 nm. Furthermore, WDS maps of silicon, sulfur and gold elements for synthesized SGP particles confirm complete formation of core-shell structures.

silica nanoparticles, cationic gold-thiourea complex, copper anode slime, gold extraction, core-shell nanoparticles