Core–shell structured Fe3O4/PANI microspheres and their Cr(VI) ion removal properties

Magnetic composite microspheres present a promising candidate for applications in water treatment, enzyme immobilization, drug delivery, catalysis, and sensors. In this paper, we report on the surfactant-free synthesis of well-defined Fe3O4/PANI microspheres through an interfacial polymerization approach. The as-prepared magnetic composite spheres show good dispersion, core–shell structure, and high magnetization. Also, the Fe3O4/PANI microspheres were tested as an adsorbent to remove Cr(VI) ions from water, and were found to have a strong adsorption capacity of ca. 200 mg g−1. The adsorption isotherm for Cr(VI) adsorption on Fe3O4/PANI microspheres follows the Langmuir isotherm model, and the adsorption process meets the pseudo-second-order kinetics. After reuse five times, the adsorption capacity of Fe3O4/PANI microspheres retains 90% of the initial value, indicating that the Fe3O4/PANI microspheres can serve as an excellent regenerable Cr(VI) adsorbent.