Kinetic, thermodynamic, and equilibrium studies for adsorption of azo reactive dye onto a novel waste adsorbent: charcoal ash

This paper investigates the usability of activated charcoal ash for removal of reactive azo dye from aqueous solution. Firstly, elemental composition and surface characteristics of the ash have been examined by using X-ray fluorescence and scanning electron microscopy. The effects of pH, ash dosage, initial dye concentration, agitation period, agitation speed, and temperature were determined by batch experiments. Calculated thermodynamic parameters indicated exothermic and spontaneous characteristics of the adsorption process. Langmuir, Freundlich, and Temkin adsorption isotherms were applied to examine the efficiency of charcoal ash. The obtained correlation coefficients and the considered isotherm parameters showed fitness of the applied isotherm models. Pseudo-second-order kinetic model was found to best represent the kinetic data considering closer values of experimental and calculated dye amounts adsorbed by unit ash mass. Results of the study demonstrated usability of activated charcoal as a promising adsorbent in dye adsorption.