Agglomeration-Free Fe₃O₄anchored via nitrogen mediation of carbon nanotubes for high-performance arsenic adsorption

We report a highly efficient method for arsenic adsorption using the agglomeration-free Fe3O4 nanoparticles (NPs) attached on N-doped carbon nanotubes (NCNTs), where the size-controlled NPs have been fabricated via the so called the "N-mediated nucleation"of NCNTs. The binding characteristics of NPs were further clarified via first-principles calculation and support that pyridine-like nitrogen states results in formation of ∼6 Å pores in sizes on the synthesized NCNTs. Moreover, we demonstrate from TEM, EDS, XPS and XRD analyses that the agglomeration-free NPs in the Fe3O4 phase could be just prepared in a few minutes via their strong binding interactions with N atoms. On the other hand, NP-CNT showed agglomerated large NP clusters and non-uniform NP anchoring on the CNT surface. Indeed, the removal in the form of As2O3 or As2O5 on the NPs-NCNT is proven to be highly selective and ∼6 times higher than that on pristine magnetite NP, in addition to providing a great potential for removal of contaminated As even from the continuously flowing water.