JOURNAL of the Tunisian Chemical Society

The aim of this work is the elimination of one organic dye that is the metylene blue of raw chemical formula C₁₆H₁₈CIN₃S, 2H₂O by the adsorption technique. The used adsorbant is natural clay that is a bentonite. Its utilization requires a streamlined regime of the fluidization in order to overcome the problem of the plugging of the clay bed. In the first stage of this work two types of isotherm models were tested to determine the adsorption capacity of our clay vis-à-vis the methylene blue; that is those of Langmuir and Freundlich. We find that the model of Langmuir describes the adsorption and gives an adsorption ultimate capacity of the order of 238 mg/g. In the second stage, we built up a pilot installation so as to use it in an industrial scale. The third part is about the identification of the streamlined regime of working of the adsorption column. We localized the streamlined regime of the column adsorption, therefore the mass of clay and the speed of the solution in order to assure a good fluidization. This streamlined survey is followed by the residence time distribution survey (RTD). For it, the method of injection by impulse of a salt that is the KCl to a concentration of 1 mol/l is used. To follow the historic of this tracer, a conductimeter method is used. This part permits to identify the model of out-flow that is piston with an axial dispersing. In a last step, a modelisation of adsorption in a fluidized bed is made. This system is based on matter balance in the column of adsorption and on the equation of the model of adsorption isotherm. This one is transformed into a differential system by doing a spatial discretisation and using a Runge Kutta method.

N. Hamouda, I. Zouari, A. Gannouni, A. Bellagi

adsorption, clay, fluidised bed, hydrodynamic

Pages 29-39