The adsorption of basic dye (Alizarin red S) from aqueous solution onto activated carbon/γ-Fe2O3 nano-composite: Kinetic and equilibrium studies

The adsorption behavior of Alizarin red S (ARS) from aqueous solution onto magnetic activated carbon (MAC) nano-composite was investigated under various experimental conditions. Characterization of the obtained MAC nano-composite was achieved by FT-IR, BET, FE-SEM, EDX, XRD and VSM techniques. The influence of variables including pH, concentration of the dye, amount of adsorbents and contact time was investigated by the batch method. High maximum adsorption capacity was obtained at 108.69 mg g−1 for ARS. The equilibrium data was evaluated using Langmuir and Freundlich isotherm. The Langmuir model best describes the uptake of ARS dye, which implies that the adsorption of ARS dye onto MAC nano-composite is homogeneous. The kinetic data were analyzed using Lagergren pseudo-first order and pseudo-second equation. The pseudo-second order exhibited the best fit for the kinetic studies (R2=0.9999), which indicates that adsorption of ARS is limited by chemisorption process. This study shows that the as-prepared MAC composite could be utilized as an efficient, magnetically separable adsorbent for the environmental cleanup.