In the present study, a Cameroonian smectite was used as an adsorbent to model the adsorption kinetics of three textile dyes (malachite green, methyl red and acid blue 74) from aqueous solution in a batch system. The effects of pH and temperature were evaluated on the adsorption capacities, the times required to reach adsorption equilibrium and the adsorption mechanisms involved. It can be seen that, although the times required to reach the adsorption equilibrium are independent of the pH of the medium, the adsorption process studied is favourable in acidic media and is globally independent of temperature. Among the pseudo-first and pseudo-second-order kinetic models used to analyse the experimental data, the pseudo-secondorder model was the best suited to describe the adsorption of the three dyes onto the clay. The mechanism involved, independently of the dye, is therefore a two-step process: the transfer of dye molecules from the solution to the clay surface followed by the interaction between the molecules and the surface. The low value of activation energies indicates that the adsorption of Methyl red, Malachite green and Acid blue 74 on the studied clay is a physisorption process.
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