Sequestration ability of task specific ionic liquids towards cations of environmental interest

The metal speciation behavior of the amino functionalized 1-(2′-diethylamino)ethyl-3-methylimidazolium-based ILs, bearing anions featured by different coordination properties (chloride, perchlorate, acetate) is reported. Sequestering ability of this family of ILs towards Hg2+, CH3Hg+, Sn2+, (CH3)2Sn2+, UO22+, evaluated by the determination of pL0.5 parameter, was found to be a function of the nature of anions and/or pH. The acetate IL displayed a high affinity towards Hg2+ and CH3Hg+, both at acidic and basic conditions, with respect to chloride and perchlorate derivatives, suggesting that a cation-anion cooperation mechanism is operating in the sequestering process. Conversely, UO22+ sequestration resulted a function of pH and independent on the nature of the anion. The extraction capabilities of hydrophobic 1-(2′-diethylamino)ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide towards Hg2+ and CH3Hg+ after treatment with acetate IL were also checked. AAS measurements showed the almost complete removal of both mercury species from water solution.