Novel Mechanically Assisted Dissolution of Platinum Using Cerium(IV) Oxide

Abstract

Platinum group metals (PGMs) are important for a variety of applications, including catalysis; however, the amounts mined are inadequate relative to global requirements. Therefore, methods for the recovery of PGMs from spent resources are urgently required. Herein, we report that platinum (Pt) can be dissolved by hydrochloric acid (HCl) alone using cerium(IV) oxide (CeO2) as a solid oxidizing agent, which can minimize the highly corrosive chlorine. Pt-containing catalysts were subjected to high-energy ball milling in the presence of CeO2, and their dissolution behavior in HCl was subsequently investigated. Ball milling was found to promote direct Pt-oxidation, as indicated by the significantly increased solubility in HCl. Several analytical techniques, including X-ray diffractometry, surface area and pore size analysis, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, inductively coupled plasma mass spectrometry, and atomic emission spectroscopy, were used for characterization. This study demonstrates the environmentally acceptable characteristics of high-energy ball milling and its applicability in the recycling of important noble metal substances from waste materials.