Adsorption performance of activated carbon prepared from elephant (Elephas maximus) dung for the removal of Reactive Yellow 15 from aqueous solution

Abstract

Elephant Dung Activated Carbon (EDAC), prepared by acid treatment, was used as an eco friendly adsorbent for the removal of the textile dye, Reactive Yellow 15 (RY15) from an aqueous solution. Batch adsorption experiments were carried out to investigate the kinetic, thermodynamic and isotherm studies by varying the initial dye concentration and temperature. The adsorption kinetic data were correlated with pseudo first-order, pseudo second-order, and elovich models. Pseudo second-order kinetic model fitted very well with the experimental data. The thermodynamic parameters like Gibb’s Free energy change (ΔG0), Entropy change (ΔS0), and enthalpy change (ΔH0) were calculated. The results indicated that RY15 adsorption process was endothermic and spontaneous. The mechanism of adsorption process was determined by studying the intraparticle diffusion and liquid film diffusion models. Effects of EDAC dosage and pH on percentage removal of RY15 were studied. Maximum adsorption had taken place at pH 2. The experimental data were correlated with Langmuir, Freundlich, and Temkin adsorption isotherm models and it was best represented by Langmuir isotherm model. Adsorption capacity of EDAC was compared with different adsorbent/adsorbate systems. Desorption studies indicated the physisorption type of adsorption of RY15 onto EDAC. The effectiveness of the adsorbent was tested with an effluent collected from a dyeing industry. Competitive adsorption of various types of dyes was examined to study the performance of EDAC.