Thermosensitive Microfibril Cellulose/MnO2 Membrane: Dual Network Structure, Photothermal Smart Modulation for Switchable Emulsion Separation

Abstract

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.