Development and optimization of a carbon nanotubes–kaolinite composite for highly efficient removal of methyl red dye from aqueous solutions

The current work involves the synthesis of a composite of carbon nanotubes and kaolinite (CNTs/kaolinite). This composite was synthesized using a simple evaporation and drying method. The synthesized materials were investigated using different techniques such as the XRD technique, SEM–EDS, Sears method, and point zero charges (pzc). The activity of synthesized materials was studied by following the removal of methyl red dye (MR) from its aqueous solution by adsorption over these synthesized materials. Different adsorption parameters and conditions were conducted such as the effect of the used doses of the adsorbent, period of adsorption, effect of temperature, and pH effect. The obtained results found that the best removal efficiency of MR dye was achieved upon using a dose (0.07 g) of the synthesized composite at 25 °C, and the optimum pH was 5. Also, it was found that the removal efficiency of this dye over composite was better than that in comparison with each of kaolinite and CNTs alone under the same adsorption circumstances. The adsorption behavior of MR dye onto the CNTs/kaolinite composite is well described by the Freundlich isotherm and follows the pseudo-second order kinetic model. Additionally, the data indicates that CNTs/kaolinite are highly recyclable, indicating that they would be a cost-effective material with substantial potential for water treatment.