Characterization of Moroccan Raw and Modified Clay and Its Application in Removal of Methyl Orange Dye

Abstract

In this work, we study the characterization of raw clay extracted from Jbel Lahbib Region of Tetouan in the north of Morocco, and organo-modified clay by a cationic surfactant hexadecyltrimethylammonium bromide (CJL + HDTMA). In addition, we evaluate their potential to remove organic pollutants (methyl orange, MO) in aqueous solutions by means of the absorption techniques. All samples were characterized by XRD, FTIR, SEM-EDAX, TGA, BET, and zeta potential. The XRD results show that the principal peak d001 moved from $14.7$ to $23$ Åfor the modified clay, the specific surface area of the raw and modified clay is 68.28 and 1.47 m²/g, respectively. Furthermore, these results confirm the success of this modification. With raw clay extracted from Jbel Lehbib (CJL), the maximum adsorption capacity of MO is pH-dependent. Consequently, the MO adsorption is favored in the high acidic pH range. The adsorption kinetics of MO on both clays revealed that the equilibrium is rapidly obtained. Moreover, it is shown that the experimental data for MO adsorption on the two materials best fit the pseudo-second-order kinetic model. The adsorption isotherms indicate that the Sips and Temkin models correctly describe the adsorption of MO on the raw with experimental maximum adsorption value of 40.9 and 66.65 mg/g for raw and modified (CJL), respectively. The energy obtained from D-R model (6.9 KJ/mol for raw clay and 12.86 KJ/mol for modified clay) suggested that process is dominated by physisorption for raw clay and chemisorption for modified clay. Besides, the thermodynamic study revealed that MO adsorption by crude clay is exothermic ($\Delta H^{\circ }=-2.39$ KJ/mol), physical, and spontaneous.