Removal of Eriochrome black T dye from aqueous solutions by adsorption onto a low-cost adsorbent: pomegranate seeds wastes

Abstract

In this study, the adsorption of EBT dye from aqueous solutions onto the pomegranate seeds (PS) powder surface was investigated. The experimental design methodology has been applied to adjust the parameters, such as PS dosage, contact time, dye concentration, the temperature, and pH. Adsorption equilibrium data were analyzed by Langmuir, Freundlich, Temkin, Elovich and Harkin–Jura equations. The experimental data showed that the Freundlich and Harkin–Jura isotherms were appropriate for the EBT dye adsorption. A comparison of kinetic models was evaluated for the pseudo-first-order, pseudo-second-order, Elovich and Intrapartical diffusion kinetic models. Pseudo-second-order was found to agree will the experimental data, which indicates that physcisorption is dominant. The percentage removal was found ≈ 53% at 298 K, pH =7 of EBT dye. The thermodynamics parameters such as ΔG, ΔH, ΔS and Ea have been calculated. The results have been showed the adsorption process onto the PS surface is endothermic and nonspontaneous.  The obtained results imply that PS surface powder could be employed and have moderate affinity to remove EBT from aqueous solutions.