Efficient removal of tetrabromobisphenol A through persulfate activation by α-MnO2 nanofiber coated with graphene oxide

Abstract

The development of efficient and environmentally friendly catalysts for activating persulfate is the focus of advanced oxidation treatment of organic contaminants. Manganese dioxide (MnO2), which has a multivalent nature and is a low-toxic natural stock, has the ability to immediately oxidize pollutants. In order to further improve its catalytic performance, the α-MnO2 nanofiber coated with graphene oxide (α-MnO2@GO) was prepared by one-step hydrothermal method, and worked as a peroxmonsulfate (PMS) activator for efficient degradation of tetrabromobisphenol A (TBBPA). The structure characterization results indicate that α-MnO2 nanofibers are successfully encapsulated by graphene and assembled into a three-dimensional layered structure. The factors affecting the catalytic degradation of TBBPA by this catalyst are investigated in detail. Under optimal conditions, the highest removal ratio of TBBPA could reach 100% after treatment of 20 min by α-MnO2@GO/PMS system, and a good mineralization efficiency of up to 79.50% is obtained. Electron paramagnetic resonance detection combined with quenching experiments showed that sulfate radical and hydroxyl radical played a role in the degradation of TBBPA. Based on X-ray photoelectron spectroscopy and free radical scavenging experiments, the peroxmonsulfate activation mechanism by α-MnO2@GO was proposed. Finally, based on the discovered intermediates, two potential TBBPA degradation routes using this catalyst were suggested. This study not only provides a new strategy for improving the catalytic activity of MnO2 but also sheds new insight into the application of eco-friendly natural stock for environmental remediation.