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Endocrine-disrupting chemicals (EDCs) cause serious threats to human health. Five types of MnO 2 were synthesized and characterized. They exhibited different removal performances for three EDCs, i.e., estrone (E1), ethynylestradiol (EE2) and bisphenol A (BPA). Only δ-MnO 2 can completely remove E1 within 120 min at pH 3.0. Free Mn (III) was determined at the beginning of the reaction and participated in the EDCs removal process. Electron spin resonance (ESR) indicated that δ-MnO 2 could produce superoxide anions (·O 2 - ) and singlet oxygen ( 1 O 2 ) in the existence of methanol. The reactive oxygen species (ROS) quenching experiments showed 1 O 2 have certain contribution to the E1 removal by δ-MnO 2 . The source of ROS is mainly the lattice oxygen from δ-MnO 2 , and can be replenished through the layer structure destruction caused by the reaction between Mn(III) and E1. The ROS dependent EDCs removal by δ-MnO 2 leads to a deep understanding on this well-known oxidant., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A novel magnetic catalytic composite (MBM) was developed by compositing α-MnO 2 with a magnetic biochar containing Fe 3 O 4 . XRD and EDS confirmed the crystalline structure and the chemical composition of MBM, while the one-dimensional α-MnO 2 nanorods were observed on MBM by SEM. 4-chlorophenol as a typical toxic chlorinated organic compound was selected as the model pollutant. Even the MBM composite (MnO 2 content: 0.2 g/L) needed the same time (120 min) as the pure α-MnO 2 nanorods (0.2 g/L) to completely remove the 4-chlorophenol (10 mg/L) with overdosed peroxydisulfate (PDS), MBM indicated faster pollutant removal rate than the pure α-MnO 2 nanorods in the first 100 min. It is possible that the adsorption of 4-chlorophenol by biochar might shorten the migration pathway of the generated active species to the pollutants, resulting the boosted removal rate. MBM was stable in the neutral environment which was desirable for the efficient pollutant removal. Both the radical quenching tests and the EPR spectra identified the main active specie generated by activation of PDS through MBM was singlet oxygen possibly generated by recombination of superoxide ions from the metastable manganese intermediates at neutral pH. TOC data of the effluent ensured 63.5% of the pollutant molecules were completely mineralized after the degradation. The applied magnetic field could recover MBM easily for reuse. This work shed lights on the preparation of highly efficient and environmentally friendly catalytic composites for PDS activation in persistent pollutant removal., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)