Preparation of MES@Fe3O4@SiO2-PPy magnetic microspheres for the highly efficient removal of Cr(VI).

Amino-functionalized monodisperse polymeric microspheres have great significance in water remediation. Herein, polypyrrole (PPy)-modified silica-coated magnetic monodispersed emulsion sphere (MES) microspheres (MES@Fe₃O₄@SiO₂-PPy, MFSP) were successfully prepared via in situ polymerization for the adsorption of hexavalent chromium in an aqueous solution. The magnetism of MFSP enabled fast separation under an applied magnetic field. The results showed that MFSP exhibited outstanding adsorption for Cr(VI) (301.2 mg g⁻¹ at pH 2.0), which followed the pseudo-second-order kinetic and Langmuir isotherm models. Moreover, the MFSP can be reused in the adsorption–desorption cycle by simple elution, and the removal rate of Cr(VI) by MFSP remained above 91% after five consecutive cycles. Combined with XPS, EDS, and Zeta potential measurement for adsorption mechanism analysis, it was concluded that the removal of Cr(VI) could be attributed to both adsorption and reduction. The combination of good adsorption performance and magnetic separation makes MFSP a promising candidate for the removal of low-concentration metal ions. [ABSTRACT FROM AUTHOR]