The bifunctional composites of AC restrain the stack of g-C3N4 with the excellent adsorption-photocatalytic performance for the removal of RhB

Abstract

A bifunctional composite of activated carbon/carbon nitride (AC/g-C3N4) with the excellent adsorption-photocatalytic performance was prepared by a facile thermal polycondensation method. The as-prepared composites were characterized by XRD、 FT-IR, XPS, Nitrogen adsorption-desorption, TEM, UV–vis DRS and EIS. It was found that the stacking g-C3N4 was fragmented by AC in the process of synthesis, leading to the increased surface area and reactive sites, and facilitating the transfer of photogenerated electron-hole pairs. The adsorption kinetics and isotherms were carried out to investigate the adsorption behavior of the composites, which indicated that the adsorption behavior fitted with the pseudo-second-order model and the Freundlich adsorption model, respectively. The AC(5%)/g-C3N4 composite possessed the best remove efficiency of Rhodamine B (RhB) in the adsorption-photocatalytic process, and the adsorption capacity and the photocatalytic reaction rate were 4.3 and 4.1 times higher than that of the pure g-C3N4, respectively. Additionally, the removal efficiency of cycle experiments had decreased from 97% to 82% after 3 cycles, and then to 79% after 5 cycles, indicating the excellent stability of the photocatalyst. The mechanism of the adsorption-photocatalytic degradation of RhB for the AC(5%)/g-C3N4 was also proposed. Specifically, AC with excellent adsorption performance could enrich the contaminant around the composite, and then the fragmented g-C3N4 captured RhB molecule rapidly and degraded it easily, improving the remove efficiency of the RhB degradation.