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.

Janus smart materials with asymmetrical wettability for on-demand oil/water separation: a comprehensive review

“…The reusability of separating materials cannot be ignored in practical applications. Chen et al 89 successfully synthesized a wettability switchable MFC-based membrane (MCPP) for efficient separation of oil–water emulsions using low-cost microfibrillated cellulose (MFC), MnO 2 nanowires for efficient photothermal conversion, and thermo-responsive N -isopropylacrylamide (PNIPAM) polymer as raw materials as shown in Fig. 5c.…”

Advanced stimuli-responsive membranes for smart separation

“…The coating-from approach for stimuli-responsive membranes involves the in situ generation of coatings on the membrane surface through polymerization, 218,219 sol–gel, 220 and initiated chemical vapor deposition (iCVD). 221 This approach offers advantages such as ease of fabrication and excellent control over the coating thickness and composition.…”

Joule Heating-Assisted Crude Oil Purification by a Poly(pyrrole)-Modified Microfibril Cellulose Membrane

“…Microfibril cellulose (MFC) was extracted from shredded coconut, and the details of the extraction process can be found in our previous work. 55 The MFC shows a hollow structure with a length of ∼521 ± 147 μm, diameter of ∼13 ± 3.3 μm, and a wall thickness of 0.4 μm, as shown in Figure S1. In this experiment, crude oil (density: 0.8552 g cm −3 , viscosity: ∼3000 mPa•s at 30 °C) was obtained from the Shengli Oil Field in China.…”