Removal of Congo Red Dye from aqueous solutions using natural clay of montmorillonite type

Abstract

Natural clay of the montmorillonite type, heated at different temperatures, was studied in removal of the Congo Red anionic dye, which is a component of the wastewater of the dyeing industry by the adsorption method. It was shown that with an increase in the calcination temperature of the clay the specific surface, pore diameter and pore volume decreased. The calcination temperature also affected the adsorption properties of clay. It has been established that the largest sorption capacity with respect to the Congo Red dye is possessed by a sample heated at 104 °C. Sorption isotherms were analyzed using linear Langmuir and Freindlich equations. It was determined that the adsorption of the dye on natural clay was in good agreement with the Langmuir adsorption isotherm with a correlation coefficient of 0.9751-0.9966, which corresponded to monolayer adsorption on a uniform surface.