This article presents an improvement in the properties of environmentally friendly, inexpensive, and readily available surfaces for use in addressing a significant environmental problem: pollution from dyes generated by various industrial processes. The surface of Iraqi flint clay was acidically activated and used to adsorb methyl orange dye from its aqueous solutions. The clay surface was characterized before and after acid activation using several techniques, including Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, X-ray disperse energy spectroscopy, and field-emission scanning electron microscopy. The adsorption of methyl orange dye using flint clay before and after activation was performed in batch system under controlled operating conditions (weight of adsorbent surface, contact time, initial dye concentration, and temperature). The amount of adsorption of methyl orange dye was found to be higher at higher temperatures, with the qe value for the raw clay being 45 mg/g and for the activated clay qe value of 30 mg/g. The process data were analyzed kinetically and found to follow the pseudo-second order kinetic model, while the process data were analyzed isothermically and found to follow the Freundlich isotherm model. The thermodynamic functions of the adsorption process were assigned and found to be a non-spontaneous, endothermic, and random process on the raw clay, while it became more spontaneous, random, and endothermic, reflecting the success of the acid activation process in improving the efficiency of the Iraqi flint clay surface in removing the methyl orange dye from its aqueous solutions.
