Adsorption kinetics and thermodynamics of anionic dyes onto sewage sludge derived activated carbon

Abstract

The adsorption kinetics and thermodynamics of two anionic dyes (Reactive Brilliant Red K-2BP and Acid Scarlet GR) on the Sewage Sludge Derived Activated Carbon (SAC) were studied by batch adsorption tests. It was found that, for Reactive Brilliant Red K-2BP, four kinetic models, i.e., the pseudo-second-order model, the modified pseudo-first-order model, the pseudo-first-order model, and the intra-particle diffusion model, all showed acceptable applicability for the adsorption process. For Acid Scarlet GR, the adsorption process conformed only to the pseudo-second-order kinetic model. The adsorption processes of two dyes on the SAC were spontaneous (ΔG0 0), and accompanied by an increase in entropy (ΔS0 > 0).