Adsorption modeling of alizarin yellow on untreated and treated charcoal

Authors: MUHAMMAD SALMAN, MAKSHOOF ATHAR, UMER SHAFIQUE, MUHAMMAD IMRAN DIN, RABIA REHMAN, ATTIA AKRAM, SANA ZULFIQAR ALI

Abstract: 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 \Delta G°, \Delta H°, and \Delta S° were also calculated, which showed that a spontaneous and favorable reaction occurred for acid- and base-treated wood charcoal. The negative values of \Delta H° for acid- and base-treated charcoal indicate that the adsorption mechanism was exothermic. From the Arrhenius equation, parameter E was equal to 5.36 \times 10^{-4}kJ mol^{-1}, which corroborated the temperature dependency of the rate of adsorption.

Keywords: Adsorption, alizarin yellow, wood charcoal, Langmuir, Freundlich, Temkin, Harkin-Jura, Halsey

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