Reduced CuFe2O4 for catalytic oxidation of methyl orange by activation of persulfate: performances and mechanisms

摘要

Bimetallic Fe-0-based catalysts have been shown to be effective heterogeneous catalysts for elimination of organic pollutants by activating persulfate (PS). In this study, copper ferrite (CuFe2O4) was isothermally treated under a reducing atmosphere in order to load Fe-0/Cu-0 bimetallic nanoparticles on the surface of CuFe2O4. The reduced CuFe2O4 was then used as a magnetically separable catalyst for PS activation to remove methyl orange (MO) from aqueous solution. The experimental data followed well the pseudo-first-order kinetic model, and the reaction rate of the reduced CuFe2O4/PS system was 5.6 times greater than that of the CuFe2O4/PS system. The key operating parameters such as PS concentration, catalyst dosage and solution pH were investigated. Catalyst stability of reduced CuFe2O4 was also tested by consecutive reuse cycles. Quenching experiments and electron spin resonance (ESR) spectroscopy revealed that the main reactive species was sulfate radical (SO-). Intermediate products of MO degradation were determined by high performance liquid chromatography coupled with a high-resolution hybrid quadrupole time-of-flight mass spectrometer (LC-Q-TOF-MS) and the MO degradation pathways were proposed. Based on the analysis of catalytic activity and surface characteristics of reduced CuFe2O4, the enhanced reactivity of reduced CuFe2O4 was mainly attributed to rapid corrosion of Fe-0/Cu-0 bimetallic nanoparticles by PS. These findings illustrated that the reduced CuFe2O4/PS system may be an efficient technology for MO removal from wastewaters.