Coal fly ash/CoFe2O4 composites: a magnetic adsorbent for the removal of malachite green from aqueous solution

Abstract

A coal fly ash/CoFe₂O₄ (CFA/CFO) magnetic composite was synthesized by a facile hydrothermal synthesis method, and then used as an adsorbent for the removal of malachite green (MG) dye from water. The structure, morphology, and properties of the composite were characterized by XRF, SEM, XRD, FT-IR, BET and VSM techniques. A batch adsorption experiment on the removal of MG was performed with CFA/CFO, and the effect of various experimental parameters, such as the adsorbent dosage and contact time of MG at 25 °C, were investigated. Three isotherm models, namely the Langmuir, Freundlich, and Dubinin–Kaganer–Radushkevich (DKR) models, were applied to describe the adsorption process. The results indicated that the Freundlich and DKR models fit quite well with the experimental data. Thermal and microwave methods were used and compared in the regeneration experiment. All the results indicated that the as-prepared composite should be considered as a potential low-cost adsorbent for easy and efficient removal of MG from water.