Synthesis of porous (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O high entropy oxide catalysts for peroxymonosulfate activation toward tetracycline degradation

Abstract

The porous (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O high entropy oxide was synthesized by a facile solution combustion method. The X-ray diffraction (XRD) patterns showed that a rock-salt phase (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O nanocrystalline was successfully constructed after heat treatment above 800 °C. A porous microstructure with high specific surface area was determined by scanning electron microscope (SEM) and N2 adsorption analysis, respectively. The (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O high entropy oxide displayed excellent peroxymonosulfate (PMS) activation which could fully degrade the tetracycline (TC) within 24 min. Moreover, the effect of PMS concentration, the high entropy oxide dosage, pH value, temperature and coexisting anions on the degradation efficiency of TC was systematically studied. According to free radical quenching experiments and electron paramagnetic resonance studies, the possible mechanism of TC degradation over the (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O/PMS system was proposed. This work provided a research basis for the use of high entropy oxide for PMS activation in environmental treatment.