Synthesis of a core–shell magnetic Fe3O4–NH2@PmPD nanocomposite for efficient removal of Cr(VI) from aqueous media

The synthesis of reclaimable adsorbents with satisfactory adsorption performance and easy separation properties is necessary for environment-related applications. In this study, novel amine-functionalized magnetic Fe3O4 (Fe3O4–NH2) nanoparticles coated with poly(m-phenylenediamine) (Fe3O4–NH2@PmPDs) were synthesized successfully via oxidation polymerization. The as-prepared Fe3O4–NH2@PmPDs with a well-defined core–shell structure were characterized, and their extraordinary Cr(VI) removal capability was investigated. Fe3O4–NH2@PmPDs exhibit high adsorption capacity (508 mg g−1) and fast adsorption rate towards Cr(VI). The abundant nitrogen-containing functional groups on the surface of Fe3O4–NH2@PmPDs greatly contribute to the adsorption/reduction of Cr(VI). Moreover, the intraparticle diffusion model can be used to provide a good explanation of every stage of the process. The calculated thermodynamic parameters suggest that the adsorption of Cr(VI) onto Fe3O4–NH2@PmPDs is endothermic and spontaneous. Fe3O4–NH2@PmPDs can be easily separated, and the regenerated adsorbents still maintain high adsorption capacity. The results imply that Fe3O4–NH2@PmPDs can be regarded as a suitable material for the treatment of Cr(VI) from contaminated water.