Improvement of magnetic solvent extraction using functionalized silica-coated Fe3O4 nanoparticles

The application of hydrophobic magnetic nanoparticles functionalized with long carbon chain molecules, such as oleic acid, in the solvent extraction process results in a faster phase disengagement without affecting the extraction and stripping percentages of cobalt with Cyanex 272, as previously reported. However, the chemical stability of this organic phase is confined to aqueous solutions with a pH of 2.0 or higher. To address this limitation, this study proposed nanoparticles coated with silica and functionalized with a long carbon-chain silane (OTS) for solvent extraction. Characterization techniques such as transmission electron microscopy, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, and magnetic analysis were employed. The effect of these nanoparticles on the solvent extraction of cobalt, using various concentrations (0, 10, 20, and 30 g/L), was investigated. Results indicated that the presence of magnetic nanoparticles did not interfere with the efficiency of metal extraction and stripping. Moreover, the phase disengagement time was reduced by a factor of 25 compared to processes without magnetic nanoparticles.