Fabrication of Fe3O4@UiO-66-SO3H core–shell functional adsorbents for highly selective and efficient removal of organic dyes

A novel magnetic nanocomposite named Fe3O4@UiO-66-SO3H with a core–shell structure was first synthesized via a feasible step-by-step assembly strategy, and then employed as an adsorbent to remove methylene blue (MB) from aqueous solution. The characterization by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy proved that the Fe3O4@UiO-66-SO3H core–shell nanocomposite was successfully prepared. And the as-synthesized Fe3O4@UiO-66-SO3H had a strong affinity towards MB and the maximum adsorption capacity was 297.3 mg g−1. The adsorption of MB could be basically completed within 15 min. The kinetic and isotherm studies indicated that adsorption data could be well fitted to the pseudo-second-order model and Langmuir model. Significantly, Fe3O4@UiO-66-SO3H could selectively adsorb MB from a mixed solution due to the charge-selectivity effect and possessed good reusability. The electrostatic interaction and the π–π interaction were assumed to play a vital role in the adsorption process. All in all, the current study provided a promising sorbent for the efficient and selective removal of MB from dye-containing wastewater.