Efficient activation of peroxymonosulfate by Co-doped mesoporous CeO nanorods as a heterogeneous catalyst for phenol oxidation.

Sulfate radical-based advanced oxidation processes have received considerable attentions in the remediation of organic pollutants due to their high oxidation ability. In this study, a novel CoO/CeO catalyst was fabricated and employed as a peroxymonosulfate (PMS) activator to generate SO for phenol degradation. The CoO/CeO catalyst exhibited a good catalytic performance at a wide pH range of 3.4 to 10.8, and 100% phenol (20 mg/L) was removed within 50-min reaction under optimal conditions with 0.2 g/L catalyst and 2.0 g/L PMS at room temperature. The transformation products and total organic carbon during the degradation process were also determined. The quenching experiments and electron paramagnetic resonance spectra revealed that sulfate radical (SO) rather than other species such as singlet oxygen (O) and hydroxyl radical (OH) was primarily responsible for phenol degradation in the CoO/CeO/PMS system, and a rational mechanism was proposed. Moreover, the recycling experiments as well as low cobalt leaching concentration manifested satisfactory reusability and stability. The effects of various inorganic anions and natural organic matter in real water matrix on phenol oxidation were further evaluated. We believe that the CoO/CeO composites have promising applications of PMS activation for the degradation of organic pollutants in wastewater treatment.