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

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 (CuFe 2 O 4 ) was isothermally treated under a reducing atmosphere in order to load Fe 0 /Cu 0 bimetallic nanoparticles on the surface of CuFe 2 O 4 . The reduced CuFe 2 O 4 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 CuFe 2 O 4 /PS system was 5.6 times greater than that of the CuFe 2 O 4 /PS system. The key operating parameters such as PS concentration, catalyst dosage and solution pH were investigated. Catalyst stability of reduced CuFe 2 O 4 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 ·− 4 ). 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 CuFe 2 O 4 , the enhanced reactivity of reduced CuFe 2 O 4 was mainly attributed to rapid corrosion of Fe 0 /Cu 0 bimetallic nanoparticles by PS. These findings illustrated that the reduced CuFe 2 O 4 /PS system may be an efficient technology for MO removal from wastewaters.