Fabrication of Epigallocatechin-3-gallate (EGCG) functionalized Mn3O4 for enhanced degradation of carbamazepine with peroxymonosulfate activation

Abstract

Peroxymonosulfate activation via heterogeneous catalyst was broadly applied for the treatment of PPCPs. In this work, a novel material of Epigallocatechin-3-gallate (EGCG) fuctionalized Mn3O4 nano-octahedra (E@MO) was synthesized and utilized for the degradation of carbamazepine. Various technologies such as X-ray diffraction, Fourier transform-infrared spectroscopy, Scanning electron microscope, Transmission electron microscope, Brunauer-Emmett-Teller and X-ray photoelectron spectroscopy were employed for the characterization of the as-synthesized catalyst. The results depicted that under the conditions of CBZ concentration 5 mg/L, PMS concentration 1 mM, catalyst dosage 0.2 g/L, initial pH 5.8 and 25 °C, the targeted pollutant could be totally degraded in 60 min with a rate constant of 0.0622 min−1. When temperature raised to 45 °C, CBZ was removed completely in 20 min and the rate constant (0.1668 min−1) was 2.59 times than that of 25 °C, implying the degradation process was an endothermic reaction. Scavenging experiments and EPR analysis confirmed the main reactive oxygen species generated in the reaction were sulfate radical (SO4•) and hydroxyl radical (•OH), while SO4• serviced as the leading role. Due to the reduction property of EGCG, compared with bare Mn3O4, the CBZ degradation was markably enhanced and the degradation reaction were accurately matched with the pseudo first-order kinetics equation. The possible twelve intermediates produced in the decomposition of CBZ were identified by HPLC-MS/MS, their ecotoxicity were evaluated and compared by ECOSAR model. Together with the consequences, the degradation mechanism of CBZ in the E@MO/PMS system was propounded.