Adsorptive removal of indigo carmine dye using activated carbon: kinetic and isotherm study

Abstract

In this study the removal of Indigo Carmine (IC) dye by batch adsorption using Commercial Activated Carbon (CAC) was carried out. The characterization of adsorbent was done by Structural Engineering and Materials (SEM) and Energy Dispersive X-Ray Analysis (EDX) to know the surface morphology and various elements present in the adsorbent. The operational parameters such as contact time (0-120 min), adsorbent dose (0.1-1g/L) and initial dye concentration (25-150 mg/L) was varied to know the effect of removal of indigo carmine dye from aqueous solution. The adsorption data was compared with various kinetic models as pseudo-first-order, pseudo-second-order, intra-particle diffusion, liquidfilm diffusion and Elovich models and isotherm models such as Langmuir, Freundlich, Temkin, Elovich and Dubinin and Radushkevich models. The optimum contact time and adsorbent dose was found to be 40 min and 0.8 g/L, respectively. The experimental data best fitted the pseudo-second-order kinetic model with R2 > 0.99 and Langmuir isotherm model (R2 = 0.997). The Langmuir's maximum adsorption capacity (qm) was 28.74 mg/g.