A novel graphene oxide-carbon nanotubes anchored α-FeOOH hybrid activated persulfate system for enhanced degradation of Orange II

Persulfate activation has been applied as one of the efficient advanced oxidation processes (AOPs) to remediate polluted environments. In this study, a novel alpha-FeOOH anchored by graphene oxide (GO)-carbon nanotubes (CNTs) aerogel (alpha-FeOOH@ GCA) nanocomposite activated persulfate system (alpha-FeOOH@GCA + K2S2O8) was applied for decolorization of Orange II (OII). The decolorization of OII was remarkably enhanced to a level of similar to 99% in this system compared with that of pristine alpha-FeOOH (similar to 44%) or GO-CNTs (similar to 18%). The enhanced catalytic activity of alpha-FeOOH@GCA was due to the formation of a heterojunction by alpha-FeOOH and GO-CNTs as confirmed by the presence of Fe-O-C chemical bonds. The degradation intermediates of OII were comprehensively identified. The proposed degradation pathway of OII begins with the destruction of the conjugated structures of OII by the dominant reactive oxygen species, surface-bound SO4 center dot-. The decolorization efficiency of OII by the alpha-FeOOH@GCA activated persulfate system decreased from the first to third cycle of recycling. Ultraviolet (UV) irradiation or introduction of a small amount of Fe2+ could restore the activation of this system. The results show that the alpha-FeOOH@GCA persulfate activation system promises to be a highly efficient environmental remediation method for organic pollutants. (C) 2019 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.