Preparation and thermal properties of organically modified bentonite with ionic liquids

Author(s): Boumediene Haddad, Didier Villemin, Karima Dahamni, Habib Belarbi, Taqiyeddine Moumene, Serge Bresson, Ahmed Haouzi, Mustapha Rahmouni

Local bentonite claywas organicallymodified via cation exchange reaction using four ionic liquids (ILs: MPrPI,MPrPPI,BMIMandBrPrMIM) differing in their chemical architecture. In order to confirm the insertion of these ILs in layered silicates, basal spacings of interlamellar structure, have been characterized using X-ray diffraction (XRD) analysis, results indicate that the interlayer spacing of the piperidiniumorgano-bentonite ranged from14.46 to 14.86 Å, while it ranged between 13.10 and 14.46 Å in imidazolium organo-bentonite. More specifically, a monolayer configuration of ILs within the interlayer space was indicated by XRD results. To obtain information on the thermal stability and degradation products, thermals properties of these imidazolium and piperidinium ions exchanged on the surface of bentonite were investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA/DTG) fromroom temperature to 400°C. These thermal measurements revealed that organobentonite showed two distinct regions; (I) from 50 to 150°C corresponds to the removal of adsorbed water and the elimination of the water species coordinated to the interlayer cations; (II) thermal degradation of ionic liquids took place in the temperature range of 150 - 350°C, also, the imidazolium modified bentonites were thermally more stable than those modified with piperidinium. These results seem to be promising regarding to the potential application of these modified bentonites as adsorbents or for the melt processing preparation of nanocomposites.

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