Equilibrium, Isotherm, Kinetic and Thermodynamic Studies of Removal of Crystal Violet by Adsorption onto a Natural Clay

This study reports the adsorption of crystal violet (CV) cationic dye on natural clay originated from Agadir region (south Morocco) through batch adsorption experiment, in order to develop a low-cost, natural, eco-friendly and alternative adsorbent for the removal of organic pollutants. Several analytical techniques (XRD, BET, TDA, TGA and FTIR) were used to characterize the studied material. The effect of different parameters were studied such as pH (3–10), adsorbent mass (0.02-0.3 g), contact time (20–120 min), initial dye concentration (100–900 mg/L), and temperature (25–65 °C) on the adsorption of CV dye. The results Showed That CV adsorption on the natural clay depends on pH, initial dye concentration and temperature. The adsorption equilibrium data were fitted in Langmuir, Freundlich and Timken adsorption isotherm models. The adsorption data obtained were well described by Langmuir isotherm model with correlation coefficients (R2 =0.99). Maximum adsorption capacity of clay was found to be 250 mg/g. Adsorption kinetics were well fitted by Pseudo-second order kinetic model (R2= 0.999). Thermodynamic study revealed that the adsorption of CV on clay is spontaneous physical sorption process, endothermic and favorable. Experimental results indicate that the clay studied is a promising adsorbent for the removal of cationic dye molecules from aqueous solutions.

Keywords:

Adsorption , Clay , Dye , Kinetic , Isotherm models , Thermal Analysis