Magnetic Fluids Assisted Electro-Leaching of Metals

Abstract

In current research, micro and nanoparticulate electrode materials have taken their place because they offer a large internal surface area with respect to the macroscopic dimensions of such electrodes [1]. The nano-impact method is a powerful tool that enables the characterization of individual particulate nano-objects in solution and study of their reactivity [2]. A three electrodes setup system working as a standard electrochemical cell is typically used. Magnetite (Fe3O4) nanoparticles with the strongest saturation magnetization of all naturally occurring iron oxides, combined with properties such as low toxicity, good biocompatibility, high stability, and low production costs, have attracted a lot of interest [3]. There is also substantial interest in their use as magnetic fluids, in data storage, in catalysis, and as electrode materials.In this work, magnetite micro and nanoparticles have been synthetized by chemical precipitation method in presence of surfactants or functional organic polymer. The use of surfactants to stabilize these synthesized nanoparticles is crucial, as Fe3O4 nanoparticles have high surface energies and tend to aggregate. Magnetic fluids constituted by dispersed functionalized magnetite particles are used as particulate electrode in different fluids and characterized into a three electrodes cell in order to evaluate their electrochemical behavior. A deeper understanding of the particulate electrode has been performed in situ on supported particles through electrochemical AFM/STM measurements, highlighting the behavior of the single aggregate. Together with the charge transfer characterization as a function of particles size and concentration, functionalization and fluid composition, practical applications of the particulate electrodes will be presented. Specifically, the use of particulate electrodes in the electrochemical metal recovery, showing the ions adsorption properties of magnetite particles as a function of surface functionalization and their electrochemical reduction at the magnetic fluid/current collector interphase will be discussed for specific systems, e.g. copper and lithium.1.V. Noack, H. Weller, A. Eychmu1ller, J. Phys. Chem. B, 106 (2002) 8514-85232. S.V Sokolov et al., Phys.Chem.Chem.Phys., 19 (2017) 283. K. Murugappan, ChemElectroChem, 1 (2014) 1211 – 1218