A greener way to extract metal ions from water is being developed by US chemists.

A greener way to extract metal ions from water is being developed by US chemists. 

Removing metal cations from water sometimes needs two extractants - for example, one to neutralise the cation’s charge by forming a complex, and another to replace remaining hydrating water molecules. The combined effect of the two extractants working together can be greater than the sum of them employed individually - a synergistic effect.

Mark Dietz and colleagues from Argonne National Laboratory, have demonstrated such a synergistic effect using a combined ionic liquid-crown ether system to extract strontium ions from water.

Ionic liquids have garnered intense interest as ’green’ alternatives to conventional organic solvents in wide ranging applications. In their studies Dietz and his colleagues found that extraction into ionic liquids was especially amenable to this kind of synergistic enhancement.

Experiments continue, with this work raising the possibility of forming predictive guidelines for designing effective green synergistic systems.

Philip Earis

D C Stepinski et al, Green Chem., 2005 (DOI:10.1039/b414756a)