Silica Supported Ionic Liquids for the Efficient and Selective Recovery of Platinum and Palladium from Aqueous Media

Platinum (Pt) and palladium (Pd) are considered critical elements due to their scarcity and high demand for important technologies, namely, in automotive catalytic converters. Therefore, sustainable technologies that are able to selectively extract such metals from secondary sources are extremely important. This work focuses on the preparation and evaluation of silica gel modified with ionic liquids (ILs) as alternative materials to recover Pt(IV) and Pd(II) species from aqueous media. The approach described here offers a way to reduce the amount of ILs employed in common liquid–liquid extraction methods for these metal species. The sorption equilibrium data obtained are well described by a Dubinin–Radushkevich isotherm model, with the SIL containing 1-methyl-3-propylimidazolium chloride having maximum equilibrium concentrations of 51.0 mg/g and 22.3 mg/g SIL for Pt and Pd, respectively. The gathered results pave the way for the use of materials modified with ILs in the recycling of obsolete automotive catalytic converters.