Adsorption of imidazolium and pyridinium ionic liquids onto montmorillonite: characterization and thermodynamic calculations

L. Reinert (1) , Khaled Batouche (2) , Jean-Marc Lévêque (1) , Fabrice Muller (3) , Jean-Michel Bény (3) , Brahim Kebabi (2) , L. Duclaux (1)

1 LCME - Laboratoire de Chimie Moléculaire et Environnement
2 LPTE
3 ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327

Five first generation ionic liquids (RTILs : BMImCl, OMImCl, AMImCl, BPyBr and OPyBr) were intercalated into the layered structure of a Na-montmorillonite by dispersion in aqueous solutions ([RTIL] ⩽ 20 mmol.L-1). For all ionic liquids, the intercalation expanded the spacing of the silicate layers, as measured by X-ray diffraction. FTIR, thermogravimetric analyses and sodium titrations of the solutions after intercalation proved the adsorption of the RTILs through a cation exchange mechanism. Adsorption isotherms, done at pH = 7 and at 25°C, displayed that the maximum adsorption capacity of the substrates was closely linked to the nature of the organic cation and the length of the alkyl chain (BPyBr > OPyBr ∼ AMImCl ∼ BMImCl > OMImCl). For the five RTILs, calculated parameters obtained from the adsorption isotherms studied at 3 temperatures (25°C, 40°C and 55°C) concluded to an endothermic and spontaneous adsorption reaction.

Keywords: Montmorillonite; Ionic liquids; Adsorption; Thermodynamic parameters

Domains: Continental interfaces, environment; Global Changes

L. Reinert, Khaled Batouche, Jean-Marc Lévêque, Fabrice Muller, Jean-Michel Bény, et al.. Adsorption of imidazolium and pyridinium ionic liquids onto montmorillonite: characterization and thermodynamic calculations. The Chemical Engineering Journal, 2012, 209, pp.13-19. ⟨10.1016/j.cej.2012.07.128⟩. ⟨insu-00723254⟩