Removal of Basic Dyes from Aqueous Solutions by Adsorption onto Moroccan Clay (Fez City)

Abstract

The main objective of this study was to investigate the potential of natural clay obtained (from Fez city, Morocco) as an adsorbent for the removal of basic dyes (Astrazon Blue BG and Astrazon Yellow 7GLL) from liquid effluents. Natural clay was characterised using different physical-chemical methods, including nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), pH of the point of zero charge (pHPZC) and Boehm titration method. The clay was tested to remove various textile dyes from the aqueous solution at room temperature. Parameters such as initial dye concentration, solution pH, adsorbent dosages and contact time were performed in a batch system for controlling the operating conditions. Experimental results data indicated that the adsorption process is a fast and spontaneous reaction. A pseudo-second-order kinetic model provides the best fit to the experimental data of BG and YL adsorption onto the natural clay. Theadsorption isotherm data of both the dyes onto the natural clay were fitted well to the Langmuir model. A maximum monolayer adsorption capacity of 101 mg.g-1 for BG and 127 mg.g-1 for YL are obtained at 298.15 K.The results suggest that the natural clay could be used as an inexpensive adsorbent for the removal of the textile dyes from aqueous solutions.