Extraction of Platinum Group Metals and Gold from Industrial Environments into Deep Eutectic Solvents

A new technique for selective separation and preconcentration of gold and platinum group metals (platinum, palladium, rhodium, iridium, ruthenium) from model chloride media into hydrophobic deep eutectic solvents without the use of any chelating agents have been presented for the first time. The technique consists in extraction of precious metals into an eutectic solvent based on tetraoctylammonium bromide (TOAB) and carboxylic acid. The extraction efficiency of metals from model technological solution in 0.1 M HCl in the presence of 100 g/L NaCl were 99.7-100% for Au, Pt and Pd; 91.8% for Ru; 54.1% for Ir; 45.3% for Rh using the TOAB/Hexanoic acid eutectic solvent. The procedure does not involve the use of toxic, volatile or flammable solvents and can be a «green» alternative to traditionally used approaches.