Chestnut-Shell-Derived Magnetic Porous Carbon for Removing Malachite Green Dye from Water

Abstract

A CoFe-based magnetic biomass-derived porous carbon was synthesized via a simple impregnation/calcination method by using chestnut shells as the raw material. The materials were characterized via powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and specific surface area and zeta potential analyses. Further, the effect of calcination temperature on the properties of the synthesized materials was investigated. The results indicated that the calcination temperature had a significant impact on the crystal form and morphology of the materials. The maximum adsorption capacity of the material calcinated at 600°C (CSCF-6) for malachite green (MG) was 69.93 mg/g (0.1916 mmol/g). Furthermore, the MG-adsorption efficiency of CSCF-6 was greater than 90% after repeated use for 7 times and the used CSCF-6 could be recycled easily by applying an external magnetic field. The process of the adsorption of MG onto CSCF-6 could be described by the Langmuir adsorption isotherm model. Further, the results of the adsorption kinetics study showed that the adsorption process fitted well with the pseudo-second-order kinetics model, indicating that the adsorption process was mainly controlled by chemical adsorption. Moreover, the results of the thermodynamic analysis indicated that the adsorption process was spontaneous and endothermic, and higher temperatures were conducive to the adsorption.