Characterization and application of natural Moroccan material for methyl violet 2B dye removal from aqueous solution.

Abstract

In this paper, a natural Moroccan material from the Nador area in the north east of Morocco was studied as an adsorbent to remove methyl violet 2B dye from aqueous solutions. This material has never been studied before in this region, and it will be used in its raw state. It was collected and characterized by X-ray diffraction, FTIR spectroscopy, scanning electron microscopy, X-ray fluorescence, thermal analysis, N2 gas adsorption-desorption, pHPZC, and Brunauer-Emmett-Teller (BET). The studies are realized with a 500-µm grain size and 182m2/g BET surface area. XRD showed the presence of significant peaks belonging to natural zeolite type clinoptilolite-Ca and minor phases. Several parameters were studied such as contact time, adsorbent mass, initial dye concentration, initial pH solution, the particle size of the material, and temperature. Out of the three isotherm models investigated after 60min of contact time in the experiments, the Langmuir model gave the best fit to the experimental data (R2 = 0.99). The results of kinetic and thermodynamic studies revealed that the adsorption process obeyed pseudo-second-order, spontaneous (ΔG° < 0), endothermic (ΔS° > 0). The adsorption of methyl violet 2B dye is chemisorptions and physisorption. The maximum theoretical adsorption capacity was 30.30mg·g-1 at 23°C for a particle diameter of 500µm. The desorption study shows that the material can be desorbed using solvents. The reuse study indicates that the same amount of natural zeolite can be used several times which makes the process efficient and sustainable. The obtained results indicate that the country of Morocco has natural zeolite among its resources and that it can be used as an efficient adsorbent for the removal of dyes.