Removal of hexavalent chromium from water using Fe-grown carbon nanofibers containing porous carbon microbeads

The present study describes the adsorption of hexavalent chromium (Cr(VI)) ions using the Fe nanoparticle (NP)-containing carbon nanofibers (CNFs) grown on porous carbon microbeads (∼0.5 mm) as adsorbents. The porous carbon beads were produced by carbonization and activation of the phenolic precursor-based polymeric beads synthesized by suspension polymerization. The Fe NPs were in situ incorporated within the polymeric beads during polymerization. CNFs were grown inside the beads by chemical vapor deposition using the Fe NPs as the metal catalyst and benzene as the carbon source. Adsorption tests were performed to determine the removal efficiency of the adsorbents for Cr(VI) over the concentration range of 10–150 ppm in water under batch and dynamic (flow) conditions. The results revealed that the prepared adsorbents had significant adsorption capacity (∼41 mg g−1) for Cr(VI), which was comparable or larger than that of the materials discussed in the literature. Moreover, the uptake of the solute during flow was approximately the same as that obtained under batch conditions, signifying negligible mass transfer resistances. The Fe-CNF-grown porous carbon beads prepared in this study may be used as packing materials in columns for the effective removal of Cr(VI) ions from wastewater under flow conditions.