Basic activation of lower Eocene clay from Meknassy-Mezzouna basin (centerwestern Tunisia), synthesis of zeolite and clarification of soybean oils

The present work is interested particularly in a basic activation of smectitic clay by solid Na2CO3. The clay samples, belonging to Ypresian Chouabine formation, are taken from the lithological section made in the Oued Errizgui (Jebel Meheri El Jebbes) in the Meknassy-Mezzouna basin. Chemical characterization and mineralogical study shows that studied clays are mostly smectitic and associated with a small amount of sepiolite and palygorskite. The accessory minerals correspond to quartz and dolomite. Moreover, relatively high specific surface (50.47 m2/g) encourages the activation of these clays by Na2CO3. Thus, the optimal activation conditions were obtained for 5% Na2CO3 at 75 °C during 1 h. Under these conditions, the specific surface of smectitic clays increases to 58.63 m2/g. The basic activation can cause dissolution of dolomites, crystal grow of zeolites, recrystallization of smectite and Na = Ca ionic exchange between Ca-smectite and basic solution. The activated smectitic clays provide better results compared to those given by the Tonsil product used for the clarification of neutral soybean oils by the refinery of SATHOP and SOZITEX companies. In fact, the bleaching power of the activated clay is much better (71.48%) than that of the Tonsil (56.12%). This is corroborated by the visual examination of the clarified oils.