Adsorption equilibrium study of direct blue 71 (DB71) dyestuff on fatsa-ordu na-bentonite

In this study, the characterization and adsorption properties of Direct Blue-71 dye were investigated using Fatsa-Ordu Na bentonite, a low-cost adsorbent. In all adsorption experiments, adsorbent initial concentration, adsorbent dosage, contact time, and temperature were considered as functions. Temkin, Langmuir, and Freundlich adsorption equations were used to explain the equilibrium isotherms. It was determined that the adsorption studied was suitable for the Langmuir equation. In addition, both pseudo-first-order and pseudo-second-order diffusion models were used in addition to the intraparticle diffusion model for the kinetic data to be determined. The experimental data obtained showed that it fit the pseudo-second-order kinetic model. Thermodynamic parameters such as enthalpy, entropy, and Gibbs free energy were examined for Fatsa Na bentonite samples. The recorded data show that the adsorption is a spontaneous process. A positive enthalpy indicates that the adsorption is endothermic. Positive entropy data are due to some changes on the adsorbent surface. Characteristic results showed that Fatsa Na bentonite can be used as an alternative to commercial adsorbents in the removal of Direct blue -71 from aqueous solution and wastewater.