Adsorption of Indigo Carmine Dye onto <i>Acacia Nilotica</i> (Babool) Sawdust Activated Carbon

Abstract

The current study reports the utilization of Acacia nilotica (babool) sawdust activated carbon (AAC) for indigo carmine (IC) dye adsorption from aqueous medium. The surface area and surface chemistry of AAC were studied using SEM and FTIR analyses. Batch studies were performed to determine the influence of different adsorption factors, viz, AAC dose, solution pH, time of contact, IC concentration, and absolute temperature on the adsorption of IC dye. Five adsorption isotherm equations were used to analyze experiment data. To optimize and find the most suitable isotherm, HYBRID, MPSD, and ARE functions were applied. The mechanism of adsorption has been analyzed by considering pseudo first and second-order kinetic equations. The adsorption study revealed that, the maximum removal of IC was found to be about 99.45 and 75.82% at the concentrations of 50 and 500 mg/L with adsorption uptake of 4.792 and 37.908 mg/g, respectively, for 10 g/L of AAC dosage, 2&nbsp;h contact time and 303&nbsp;K temperature. The equilibrium study revealed that, adsorption data follows all isotherm equations for IC adsorption on AAC. The kinetic study revealed that, adsorption of IC onto AAC followed the second-order model of kinetics. Thermodynamic study illustrated endothermic nature of adsorption. From the study, it is found that the AAC can be utilized for the adsorption of dyes and similar other adsorbates materials from wastewaters.