Ionic liquids (ILs) are salts that are molten at ambient temperatures. ILs have a variety of useful properties, including negligible vapor pressure, good electrochemical stability and ionic conductivity, and unique solvent characteristics. When combined with a solid material as a scaffold, ILs can form hybrid materials known as �ionogels,� which offer many of the favorable properties of ILs in a solid form. ILs and ionogels are being investigated for electrochemical, synthesis, and separations applications, especially in uses where they might replace hazardous volatile chemicals. ILs are often described as �green� chemicals, based partially on the assumption that they are recyclable. While this principle has been proven for ILs used as solvents, IL recycling from ionogels is not common practice. Here, a simple, low-energy, water-based IL reclamation process is demonstrated using two types of silica-supported ionic ionogels incorporating several common ionic liquids [1]. More than 90% of the IL can be separated from the ionogel silica scaffold by submerging the ionogel in water. No additional energy input is required. It is posited that water is able to compete with the hydrophobic IL for access to the hydrophilic silica scaffold surface, liberating the IL from the ionogel structure. Over 70% of the original IL mass can be recovered using spontaneous water-based separation; transfer losses are expected to decrease with process scale-up. Recovered ILs exhibit similar electrical performance to the virgin materials in a double layer capacitor structure and are suitable for reuse as electrolytes in electrochemical devices.[1] Horowitz, A. I., Wang, Y. & Panzer, M. J. �Reclamation and reuse of ionic liquids from silica-based ionogels using spontaneous water-driven separation.� Green Chem., 2013,15, 3414-3420.

Low-energy recycling of ionic liquids from silica-supported ionogel electrolytes using spontaneous water-driven separation

248th National Meeting (2014)

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