N-doped porous carbon with magnetic particles formed in situ for enhanced Cr(VI) removal

• N-doped porous carbon with magnetic nanoparticles (Fe3O4 and Fe) formed in situ was fabricated.
• A very quick adsorption property for the removal of Cr(VI) was observed.
• Adsorbent with both negatively and positively charged groups.
• Magnetic nanoparticles inside showed perfect magnetic separation performance.

A newly designed N-doped porous carbon with magnetic nanoparticles formed in situ (RHC-mag-CN) was fabricated through simple impregnation then polymerization and calcination. The doped nitrogen in RHC-mag-CN was in the form of graphite-type layers with the composition of CN. The resultant nanocomposite maintained a high surface area of 1136 m2 g−1 with 18.5 wt% magnetic nanoparticles (Fe3O4 and Fe) inside, which showed a saturation magnetization (Ms) of 22 emu/g. When used as an adsorbent, the RHC-mag-CN demonstrated a very quick adsorption property for the removal of Cr(VI), during which 92% of Cr(VI) could be removed within 10 min for dilute solutions at 2 g L−1 adsorbent dose. The high adsorption capacity (16 mg g−1) is related to the synergetic effects of physical adsorption from the surface area and chemical adsorption from complexation reactions between Cr(VI) and Fe3O4. Importantly, the basic CNs in RHC-mag-CN increase its negative charge density and simultaneously increase the adsorption of metallic cations, such as Cr3+ formed in the acid solution from the reduction of Cr(VI). The formation of magnetic nanoparticles inside not only supplies complexing sites for the adsorption of Cr(VI), but also shows perfect magnetic separation performance from aqueous solution.

N-doped porous carbon with magnetic nanoparticles (Fe3O4 and Fe) formed in situ was fabricated through a simple impregnation then polymerization and calcination method, which showed a quick and enhanced Cr(VI) adsorption property as well as perfect magnetic separation performance.Figure optionsDownload high-quality image (268 K)Download as PowerPoint slide