A new approch to sepiolite dispersion by treatment with ionic liquids

The possibility of sepiolite disaggregation is a challenge to enhance significantly its performance and extend its application. In this direction, this work introduces the treatment of sepiolite (Sep) with three different ionic liquid (IL). The used ionic liquids were 1-methyl-3-butylimidazolium bis(trifluoromethanesulfonyl) imide (BMImTf(2)N), 1-methyl-3-octylimidazolium bis(trifluoromethanesulfonyl) imide (OMImTf(2)N) and 1-methyl-3-dodecylimidazolium bis(trifluoromethanesulfonyl) imide (DMImTf(2)N). The influence on structural, thermal properties and morphology in Sep treated with IL were evaluated using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TG), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N-2 sorption measurements, Si-29 nuclear magnetic resonance (Si-29 NMR) and zeta potential. Sepiolite structure was preserved for all the samples treated with ionic liquids. FTIR and XRD results show that BMImTf(2)N substitutes water molecules coordinated to Mg+ 2 more efficiently. Thermogravimetric analysis indicated that the interaction between Sep and IL delayed the release of water. From these data, it was also possible to confirm the presence of 5 mass% of IL in all samples. FESEM and TEM images demonstrated more disaggregated Sep fibers with IL, especially the samples treated with BMImTf(2)N. This fact is attributed to the immobilization of ionic liquid on Sep tunnels, which is coherent with Si-29 NMR analyses. The potential applications of these modified sepiolites are as reinforcing agent for polymers, template for nanostructured materials and support for catalysts.