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SUMMARY Acid activation of Bentonite for use as a vegetable oil bleaching agentThe design of various experiments in order to assess and simulate the effects of the acid activation of an Algerian bentonite on the bleaching capacity of Colza oil is described. Three key parameters of the acidic activation, namely acid concentration, contact time and temperature, were considered. The calculations made indicated that all variables display advantageous effects up to a certain level on the effectiveness of bleaching, regarded as the responsefunction. The acid concentration exerts a predominant individual effect as compared to the other parameters. Some small interactions between parameters were considered. High bleaching capacity reached 99% as optimal activation. Under accurate statistical measurements, synergy phenomena could be observed. Excessive activation is discussed in terms of loss in both porosity and acid strength. KEY-WORDS: Acid activation -Bentonite -Design of experiments -Oil bleaching.

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In this study, a convenient method was developed for the synthesis of bisimidazolium salts and bisimidazolium-ionic liquids. The products were characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), mass spectroscopy, elemental analysis and thermogravimetric analyses (TGA). The effect of the counter ion, alkyl chain length and structural isomerism on the thermal stability of the bisimidazolium salts was investigated. Ionic liquid-treated bentonite clays were prepared by ion exchange of the bisimidazolium cations with Na-bentonite. These new organoclays were characterized by X-ray diffraction (XRD), FTIR and TGA. The results show that the ionic liquid-intercalated bentonites have greater thermal stability (450-470 • C) compared with the bisimidazolium-or the diphosphonium-exchanged bentonites.