Flexible design of carbon nanotubes grown on carbon nanofibers by PECVD for enhanced Cr(VI) adsorption capacity

A novel strategy of growing carbon nanotubes (CNTs) vertically and uniformly on the surface of carbon nanofibers (CNFs) via plasma enhanced chemical vapor deposition (PECVD) was proposed to prepare a kind of CNFs-CNTs adsorption materials. The CNFs-CNTs (398.127 m2 g−1) obtained a 33 times increased specific surface area as compared to CNFs (12.986 m2 g−1). CNFs-CNTs showed remarkable adsorption capacity toward Cr(VI) in water (150 mg g−1 after an hour adsorption and 227 mg g−1 at equilibrium) due to the fascinating surface area. The effects of operating conditions including pH value, absorbing time, amounts of the adsorbents and initial concentration on Cr(VI) removal properties are evaluated. Besides, the nanocomposites exhibited excellent recyclability for adsorbing Cr(VI) that as slightly as ∼5% adsorption capacity was reduced after 3 adsorption cycles.