Equilibrium, kinetics, and Thermodynamic Studies for the Adsorption of Anionic Dyes onto Surfactant Modified Feldspar

The removal of two anionic dyes, namely Acid Black 1 and Direct Red 31, from aqueous solution was investigated using HDTMA-feldspar. The adsorption kinetics, equilibrium, and thermodynamics for the removal of the dyes were studied to determine the adsorption capacities and mechanisms of adsorption process. The effects of initial dye concentrations and temperature on the dyes removal were also investigated. Modeling of kinetic results showed that the adsorption of both dyes was well fitted by the pseudo-second-order kinetic model in the entire investigated concentration range. Freundlich model was suitable to describe the adsorption of two anionic dyes. The thermodynamic parameters associated with the adsorption process were calculated. The negative values of ΔG0 and the positive value of ΔH0 indicate that the adsorption processes are spontaneous and endothermic in the nature, respectivetely. The results show that surfactant modified feldspar can be used as an low-cost adsorbent to remove anionic dyes from wastewater.