Adsorption removal of methylene blue from aqueous solution on carbon-coated Fe3O4 microspheres functionalized with chloroacetic acid.

We report the preparation and employability of carbon-coated Fe3O4 (Fe3O4/C) microspheres functionalized with chloroacetic acid (CAA) for the removal of methylene blue (MB) in aqueous solution. The prepared magnetic microspheres (Fe3O4/C-CAA) were characterized by the following techniques: X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectrometer, vibrating sample magnetometry, and Brunauer-Emmett- Teller. The characterization results showed that Fe3O4/C microspheres were modified by CAA without any phase change. Fe3O4/C-CAA microspheres have higher adsorption capacity for MB compared to Fe3O4/C microspheres. The Langmuir, Freundlich, and Temkin adsorption models were applied to describe the equilibrium isotherms, and the Langmuir adsorption model fitted well with the equilibrium data. The pseudo-first-order and pseudo-secondorder kinetic models were used to describe the kinetics data. However, the pseudo-second-order kinetic model fitted better with the adsorption kinetics data