Removal of methylene blue from aqueous solution by montmorillonite/CoFe2O4 composite with magnetic separation performance

The montmorillonite/CoFe2O4 composite as a novel adsorbent with the magnetic separation performance was prepared by a facile, one-step low-temperature refluxing route. The structure, morphology and magnetic properties of the synthesized composite were characterized by powder X-ray diffractometer (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). Adsorption characteristics of the composite were examined by using methylene blue (MB) as an adsorbate. The effects of solution pH, dye concentration, contact time and temperature on the MB adsorption onto the composite were investigated. The results showed that the adsorption isotherm data were fitted well to the Langmuir isotherm. Adsorption kinetics of MB onto the composite followed the pseudo-second-order kinetic model. The thermodynamic parameters, such as ΔG0, ΔH0 and ΔS0, were also determined and evaluated. Moreover, the composite adsorbent had high magnetic sensitivity under an external magnetic field, which allowed its magnetic separation from water avoiding the secondary pollution.

Research Highlights
► The montmorillonite/CoFe2O4 composite can be prepared by a low-temperature refluxing route.
► The montmorillonite/CoFe2O4 composite is potential adsorbent for removal of methylene blue in aqueous solution.
► The composite adsorbent has high magnetic sensitivity under an external magnetic field, which allowed its magnetic separation from aqueous solution.