The hierarchically structured Fe3O4-MnO2-ZIF-8 composite was successfully synthesized and applied to activate peroxymonosulfate (PMS) for the degradation of bisphenol A (BPA) and other organic pollutants for the first time. Catalytic experiments revealed that the as-prepared Fe3O4-MnO2-ZIF-8 showed highly efficient catalytic activity and deep mineralization for BPA because of the loading of ZIF-8. When 60 mg/L BPA was degraded by the Fe3O4-MnO2-ZIF-8/PMS system, the removal efficiency of BPA reached 100% within 15 min and the TOC removal efficiency reached 80% within 9 min, values that were much higher than those of the catalysts reported recently. Fe3O4-MnO2-ZIF-8 can be separated conveniently from the aqueous phase under magnetic field control and shows better recyclability. Simultaneously, the Fe3O4-MnO2-ZIF-8/PMS system shows an excellent removal capability for other organic pollutants, such as phenol, tetracycline, p-hydroxybenzoic acid, and rhodamine B. Through radical quenching experiments and electron paramagnetic resonance tests, the mechanism of activation of PMS by Fe3O4-MnO2-ZIF-8 was investigated. ZIF-8 loaded on the surface of the Fe3O4-MnO2 composite can accept electrons generated from the Mn­(II)/Mn­(III)/Mn­(IV) redox conjugate triplet and react with PMS to generate more •OH and SO4 •–, thus significantly enhancing the catalytic performance. Additionally, on the basis of GC-MS analysis, the intermediates in the process of BPA degradation were tested and the possible degradation pathway was determined. This study indicates that Fe3O4-MnO2-ZIF-8 is a highly efficient catalytic material for PMS-based AOPs for the removal of various pollutants from water.

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Frequently occurring oil spill accidents have caused tremendous pollution of the ecological environment. Although various oil–water separation strategies have been developed, the design of efficient oil–water separation materials still remains a significant challenge. In this study, we report a controllable and scalable method for the fabrication of wettability-switchable membranes (MCPP) that achieved a smart temperature response and efficient emulsion separation. The pore structure of the membrane was precisely controlled by the amount of natural microfibril cellulose and MnO2 nanowires. The tensile strength of the membrane was significantly increased to 2.4 MPa with the introduction of poly(vinylidene difluoride). The temperature sensitivity of poly(N-isopropylacrylamide) resulted in a reversible wettability switch of the MCPP membrane, achieving temperature-controlled smart separation for emulsions. Interestingly, the excellent photothermal conversion properties of MnO2 nanowires realized the switch of membrane surface wettability and oil viscosity reduction, further increasing the emulsion separation performance. The MCPP membrane shows high separation permeance (O/W, 4300–5000 L m–2 h–1 bar–1; W/O, 5000–17000 L m–2 h–1 bar–1) and separation efficiency (>99.4%) for a variety of emulsions. The scalable preparation, smart temperature-sensitive wettability switch, excellent emulsion separation performance, and good reusability provide the basis for the practical application of this membrane in water purification fields.

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