Investigating the dissolution of iron sulfide and arsenide minerals in deep eutectic solvents

The speciation of iron and arsenic species in DES media after electrodissolution of five different iron sulfide and arsenide minerals was determined via UV–Vis and EXAFS spectroscopy. Iron formed FeIII O-donor complexes, whilst arsenic formed cationic AsV-O-donor complexes. The ethylene glycol component of the DES was observed to play a role in the coordination of these species. The dissolution behaviour of these minerals was found to be strongly influenced by the sulfide or arsenide moiety, with arsenide and sulfarsenide minerals dissolving more slowly than the pure iron sulfides. Dissolution rates were also correlated to the band gap, with smaller band gaps resulting in faster dissolution.