Kinetic and equilibrium studies of methyl violet adsorption from aqueous solutions by activated Algerian bentonite clay

Abstract

The industrial wastes (textile, plastic, detergents, etc.) are heavily charged in dyes which pose dangerous toxicological impacts on the environment. Various techniques have been developed for the treatment of wastewater contaminated by dyes. Adsorption processes using suitable adsorbent have shown high removal efficiency and many economical, ecological, and technological advantages. Based on their adsorption performance, Algerian bentonite clay has been first activated through an acidic treatment with HCl and characterized by nitrogen physisorption, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The adsorption equilibria and kinetics of methyl violet dye conversion onto the activated bentonite clay have been investigated in this study. It was found that the adsorption capacity of the activated bentonite clay is significantly influenced by dye concentration, initial pH, contact time, and size of the adsorbent. The adsorption agrees with pseudo-second-order kinetic. The Freundlich adsorption model was applied to experimental equilibrium data and the isotherm constants were calculated. The results indicated that the adsorption was favorable at lower pH. The monolayer adsorption capacity of the activated bentonite clay for methyl violet dye found to be 14200 μg g−1. Thermodynamic parameter, such as standard enthalpy (ΔH°), was evaluated. The activated bentonite clay was found to be a promising adsorbent for the removal of methyl violet dye from aqueous solutions.