Preparation of air-stable magnetic g-C3N4@Fe0-graphene composite by new reduction method for simultaneous and synergistic conversion of organic dyes and heavy metal ions in aqueous solution

Abstract

Although composites that consist of graphite phase carbon nitride (g-C3N4)/nanoscale zero valent iron had already been proved to be effective for conversion of organic pollutants and heavy metal ions from wastewater, however, nano Fe0 is prone to be oxidized in air. In order to prevent the oxidation and increase the stability of the aforementioned composite, this research provides a facile and economical g-C3N4@Fe0-rGO synthesis method with high photocatalytic activity for removal of RhB and Cr(VI) simultaneously under visible light. Characterization results show that dispersibility and stability of nano Fe0 were significantly increased in g-C3N4@Fe0-rGO. Moreover, g-C3N4@Fe0-rGO exhibits synergetic effects among each component of the composite, resulting in facilitating the photogenerated charges separation, enhancing the surface activity of nano Fe0, possessing the magnetic property for facile recycling. In addition, due to the formation of iron-carbon microbatteries between graphene and nano Fe0, g-C3N4@Fe0-rGO demonstrates superior activity in removal of RhB and Cr(VI). And g-C3N4@Fe0-rGO retained excellent stability without apparent loss in catalytic activity after 5 cycles. The photocatalytic tests and quenching tests reveal that nano Fe0 and ⋅OH are main factor for RhB and Cr(VI) removal. Insights into the mechanism of the enhanced reduction of Cr(VI) and photodegradation of RhB at the same time were proposed. This study is expected to provide a novel synthesis method for the design of efficient, visible light driven, and recyclable photocatalysts for environmental remediation of both organic dyes and heavy metal ions.