Valorization of Saharan kaolin for hazardous dye removal: "Basic Red 46"

Abstract

This study investigates the use of Saharan kaolin as a cost-effective and eco-friendly adsorbent for the removal of Basic Red 46 (BR46), a hazardous industrial azo dye, from aqueous solutions. The Saharan kaolin was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Batch adsorption experiments were conducted to evaluate the effects of variables such as contact time, initial dye concentration, pH, and temperature on the adsorption process. Results showed that the adsorption efficiency increased with rising initial dye concentrations and temperatures, particularly at neutral pH. The adsorption isotherms followed the Langmuir model, indicating monolayer adsorption, and the kinetics were best described by a pseudo-second-order model. Thermodynamic parameters, including enthalpy, entropy, and Gibbs free energy, confirmed the endothermic and spontaneous nature of the adsorption. These findings suggest that Saharan kaolin is a promising, low-cost alternative for removing hazardous dyes like Basic Red 46 from wastewater.