Mechanistic Aspects of Simultaneous Extraction of Silver and Gold Nanoparticles across Aqueous-Organic Interfaces by Surface Active Iron Oxide Nanoparticles.

Abstract

Surface active iron oxide nanoparticles (NPs) were used for the simultaneous extraction of water soluble Ag and Au NPs across an aqueous-organic interface from aqueous bulk. The surface activity of iron oxide NPs was achieved by using cationic Gemini surfactants of different architectures during the in situ synthesis of iron oxide NPs in hydrothermal synthesis. Aqueous bulk solubility of Ag and Au NPs was achieved by stabilizing them with conventional surfactants of different polarities such as SDS, CTAB, and DDM. The amphiphilic nature of iron oxide NPs demonstrated their remarkable ability to extract Ag and Au NPs through both hydrophilic and hydrophobic interactions. The mechanism of extraction from aqueous bulk was monitored by placing different amounts of surface active iron oxide NPs on the aqueous-organic interface and was studied with the help of UV-visible, DLS, and IR measurements. XPS and TEM measurements were used for the quantitative estimation of efficiency of extraction. Extraction was facilitated when both hydrophilic and hydrophobic interactions were participating simultaneously. Results may help in designing a suitable method for purification of industrial effluents contaminated with metal particulates simply by applying an external magnetic field rather than going through a complicated conventional filtration process.