Rapid decolorization of dye Orange G by microwave enhanced Fenton-like reaction with delafossite-type CuFeO.

Bimetallic oxide CuFeO as a new heterogeneous catalyst has shown much higher catalytic ability for activating peroxide than single-metal oxides. The present work demonstrated a synergistic microwave (MW) enhanced Fenton-like process with CuFeO for rapid decolorization of azo dye Orange G (OG). The MW irradiation dramatically enhanced the OG degradation efficiency, achieving 99.9% decolorization within 15min at pH5. The XRD analysis of reused CuFeO, together with metal leaching tests, indicated merits of recycling for CuFeO. The subsequent surface element analysis by XPS for fresh and used CuFeO showed a complex network for reactions between copper-iron redox pairs and surface hydroxyl groups, leading to a synergistic Fenton-like system accelerated by MW irradiation. In the CuFeO initiated Fenton-like reactions, several oxidant species (i.e., OH, O, electron hole, and FeO) responsible to the OG oxidation were identified by quenching experiments, showing the MW generated high temperature and "hot spots" enhanced the yield of OH by generation of electron-hole pairs. Further, the 26 detected degradation products confirmed the OH dominant oxidation of OG. This study shows that the MW-enhanced Fenton-like reaction using CuFeO has potential applications for rapid decolorization of dye effluent.