Adsorption modeling of alizarin yellow on untreated and treated charcoal

Adsorption studies of alizarin yellow from an aqueous solution were carried out on wood charcoal. Wood charcoal was subjected to various pretreatments. Various parameters such as pH, dosage amount, and contact time were studied to evaluate the adsorption behavior. Langmuir, Freundlich, Temkin, Harkin-Jura, and Halsey isotherm models were used to explain the experimental findings. The Freundlich model was best fitted, pointing out multilayer adsorption. Thermodynamic parameters such as ΔG ◦ , ΔH ◦ , and Δ S◦ were also calculated, which showed that a spontaneous and favorable reaction occurred for acid- and base-treated wood charcoal. The negative values of ΔH ◦ for acid- and base-treated charcoal indicate that the adsorption mechanism was exothermic. From the Arrhenius equation, parameter E was equal to 5.36 × 10 −4 kJ mol −1 , which corroborated the temperature dependency of the rate of adsorption