A novel magnetic activated carbon produced via hydrochloric acid pickling water activation for methylene blue removal

A novel biomass-based and low cost magnetic activated carbon (MAC) was synthesized from a peanut shell via a simple one-step method using hydrochloric acid pickling water as an activating agent. The effectiveness of MAC in the removal of methylene blue has been investigated extensively. The morphology and surface chemistry of the obtained MAC were characterized by Fourier transform infrared, X-ray diffraction spectra, scanning electron microscopy and Brunauer–Emmett–Teller surface area. A batch adsorption study was performed at varying pH levels, dye concentrations, temperatures, and adsorbent doses. In order to examine the adsorption kinetic and the mechanism of adsorption, pseudo-first-order, pseudo-second-order and intra-particle diffusion models were fitted. It was found that the equilibrium data were best represented by the Langmuir isotherm, with the maximum monolayer adsorption capacity of 201.61 mg/g at 298 K. The adsorption kinetic followed a pseudo-second-order equation. Thermodynamic study showed that the adsorption was a spontaneous and endothermic process.