Application of Carbon Microsphere Loaded with Magnetite Nanoparticles for the Removal of a Cationic Azo Dye: Efficiency and Mechanism

Abstract

Methylene blue (MB), a cationic azo dye, is harmful to the environment and human health. In this study, carbon microspheres (CMS)@magnetite was prepared to remove MB. The performance of CMS@magnetite on MB removal and adsorption mechanisms was studied. Transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller, X-ray diffraction, and vibrating-sample magnetometry were used to characterize the CMS@magnetite before and after adsorption with MB. The effects of different dosages and initial pH values on MB removal by CMS@magnetite were studied through batch experiments. Results reflected that CMS@magnetite had high removal efficiency on MB. In addition, adsorption isotherms, kinetics, and thermodynamics models were also studied. MB adsorption behavior was better described by the Langmuir model. The experimental data of MB adsorption by CMS@magnetite had a higher fitting degree with a pseudo-second-order kinetic model. In addition, reuse experiments were studied, which showed the advantage of good recycling ability of CMS@magnetite. MB was removed by CMS@magnetite through electrostatic adsorption and π-π interaction. Because of high removal efficiency, easy separation, and high performance of recycling, CMS@magnetite can be potentially used to remove MB wastewater.