Surface loaded 1-methyl-3-ethylimidazolium bis(trifluoromethylsulfonyl)imide [EMIM+Tf2N-] hydrophobic ionic liquid on nano-silica sorbents for removal of lead from water samples

This paper demonstrates, for the first time, that 1-methyl-3-ethylimidazolium bis(trifluoromethylsulfonyl) imide [EMIM+Tf2N-] hydrophobic ionic liquid can be potentially used as an excellent medium for solid phase extraction of Pb(II) from water matrices. In this work, [EMIM+Tf2N-] was directed to synthesize two newly modified nano-silica sorbents. The first modified sorbent was based on surface derivatization via physical adsorption of [EMIM+Tf2N-] onto active nano-silica particles (10-20 nm) for the formation of [NSi-OH-EMIM+Tf2N-]. The second sorbent was prepared by the direct reaction of [EMIM+Tf2N-] with amino modified nano-silica particles for the preparation of [NSi-NH2-EMIM+Tf2N-]. Surface modification of nano-silica particles was characterized and confirmed by surface coverage determination as well as instrumental analysis by using a scanning electron microscope (SEM), FT-IR and thermal analysis. The capability of newly modified nano silica sorbents for extraction of lead (II) without the need for a partition chelating intermediate was studied and optimized under different controlling variables including the effect of Pb(II) concentration, sorbent dose, pH of contact medium, shaking time, interfering anions and cations. The potential applications of [NSi-OH-EMIM+Tf2N-] and [NSi-NH2-EMIM+Tf2N-] for solid phase extraction of Pb(II) from real water matrices via multi-stage micro-column separation were also studied and evaluated. (C) 2010 Elsevier B.V. All rights reserved.