The high economic value and hardly replaceable technological properties of the platinum-group metals (PGMs), plus their growing scarcity in the Earth’s surface, justify the crucial importance of developing recycling practices for PGMs end-of-life materials. Examples of top devices relying on the use of PGMs are automotive and industrial catalysts, and electrical and electronics equipments.
This communication critically describes the most recent research about the use of solvent extraction to recover one PGM, palladium, from spent catalysts. Some groups focus on the development of schemes involving commercial extractants, while others prefer to design specific molecules to efficiently and selectively recover palladium from these specific complex leaching solutions. Examples of extractants proposed for the former schemes are Alamine 308, TBP and LIX84I; on the other side, sulfur-containing diamides, thioamides, thiocarbamates and dithioethers have recently been developed. Ionic liquids have to be mentioned too.