Physicochemical characterization of moroccan natural clays and the study of their adsorption capacity for the methyl orange and methylene blue removal from aqueous solution

Abstract

The objective of this work was the physicochemical characterization of a Moroccan natural clay from the Jorf Arfoud region (Lampert Coodinates: x = 595610, y = 101578) and its valorization in the elimination of organic pollutants (methyl orange MO and methylene blue MB) from aqueous solutions, with the adsorption technique on raw and calcined clay at 500°C. The clay was characterized by chemical analysis such as X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning electron microscopy (SEM). Crude and purified clays, consisting essentially of silica and alumina, are a characteristic property of phyllosilicates and also contain amounts of quartz, kaolinite and calcite as associated minerals. The experiments were performed after optimization of the parameters influencing the system, such as pH, adsorbent mass, initial dye concentration and temperature. The clays used absorb better the MB than MO, for an initial concentration of 10 mg/L and 20 mg/L respectively. Langmuir and Freundlich models of adsorption isotherms were applied to fit experimental equilibrium data. Results have showed that the adsorption of MB and MO followed very well the second order kinetic model on raw clay. The adsorption process was found to be exothermic in the case of MB. However, the adsorption of MO was endothermic.