Preparation of magnetically recoverable bentonite–Fe3O4–MnO2 composite particles for Cd(II) removal from aqueous solutions
Date of Issue2017
School of Materials Science and Engineering
In this study, bentonite–Fe3O4–MnO2 composite was synthesized by combining bentonite with Fe3O4 and MnO2 through co-precipitation. Vibrating-sample magnetometry, scanning electron microscopy with energy-dispersive X-ray spectrometry, transmission electron microscopy, Brunauer–Emmett–Teller measurements, and X-ray powder diffraction techniques were used to characterize the composite. The composite consists of Fe3O4 nanoparticles orderly assembled on the surface of bentonite and an outer layer of MnO2 sheets. The composite’s particles possess a saturation magnetization of 13.4–30.5 emu/g and a high specific surface area (203.89 m2/g). The adsorption behaviors of the composite in Cd(II) removal were evaluated by batch equilibrium experiments. Kinetic and isothermal data fit well the pseudo-second-order and the Freundlich models, respectively. Adsorption reached equilibrium within 30 min, and the Freundlich capacity of the composite was 35.35 mg/g. The adsorption capacity of Cd(II) increased with increasing pH and was dependent on the ionic strength. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy showed the combination of surface hydroxyl groups of the composite and Cd(II) in the solution. The prepared composite can be easily recycled and reused by taking advantage of its magnetic properties. The results show that the designed composite is a promising absorbent for the treatment of Cd-contaminated water.
Journal of Colloid and Interface Science
© 2017 Elsevier. This is the author created version of a work that has been peer reviewed and accepted for publication by Journal of Colloid and Interface Science, Elsevier. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1016/j.jcis.2017.11.063].