Chemically stable and reusable nano zero-valent iron/graphite-like carbon nitride nanohybrid for efficient photocatalytic treatment of Cr(VI) and rhodamine B under visible light

Graphite-like carbon nitride (g-C3N4) displays strong potential applications in visible-light photocatalytic for water treatment, but its applications are greatly restricted by high recombination probability of photo-generated electron-hole pairs, as well as a weak reduction ability toward the heavy metals. In this work, we reported the synthesis of nZVI-g-C3N4 nano-hybrid with highly efficiency toward the photodegradation of RhB and Cr(VI) under the visible light irradiation. The nZVI nanoparticles can well be immobilized and dispersed on the surface of g-C3N4 nanosheets by a facile borohydride-reduction method. As-synthesized nZVI-g-C3N4 has an improved photocatalytic activity much better than that of the pure g-C3N4, wherein over 92.9% of Cr(VI) and 99.9% of RhB can be removed by using nZVI-g-C3N4 . The nZVI particles not only contributes to the reduction and immobilization of Cr(VI), but also accelerates the photocatalytic degradation efficiency of RhB due to a lower recombination rate of photoexcited holes and electrons. Moreover, nZVI-g-C(3)N(4)preserves superior photodegradation efficiency after five experimental cycles. It can be attributed that nZVI-g-C3N4 photocatalyst is chemically stable, and part of nZVI can be recovered by g-C3N4. We believe that, the composite of nZVI-g-C3N4 reported here could provide guidance for the design of efficient and reusable materials to remove both the organic compounds and heavy metal ions from waste waters. (C) 2016 Elsevier B.V. All rights reserved.