Design of poly (arylene ether nitrile)@SiO2 nanoparticles super-wetting membrane for the fast separation of oil-in-water emulsions fabricated through physical confinement effect and dopamine-assisted bio-inspired deposition

The super-wetting polymer-based membrane has displayed promising application in the oily wastewater purification because of its unique anti-fouling feature. However, the creep of micro-/nano- structure on surface of membrane and wettability attenuation under harsh conditions would lead to the decrease of separation flux and efficiency, which posed a huge challenge to the membrane technology. In this study, we prepared the super-hydrophilic and underwater super-oleophobic polymer composite membrane through the one-step biomimetic deposition of sodium alginate, dopamine, and SiO2 nanoparticles onto the surface of poly (aryl ether nitrile) (PEN) membrane with wavy rough structure. Typically, the effect of physical confinement, dopamine with strong adhesion, and the co-deposition of polydopamine and sodium alginate coatings endowed the composite membrane with durable super-wetting property (water contact angle: 0° and underwater oil contact angle: 153°) and oil repellent behavior. Hence, when separating different surfactant-stabilized oil-in-water emulsions, as-prepared PEN composite membrane showed high separation flux of 762.81 ± 28.37 L·m−2·h−1 (847.5 ± 31.52 L·m−2·h−1·bar−1) and rejection ratio of 99.51 ± 0.16 %. Furthermore, the efficient separation performance and super-wetting feature of composite membrane could be retained even treating in the conditions of 4 M HCl/80 ℃ and 1 M NaOH/80 ℃, which exhibited potential application for purification of oily wastewater containing different oil/water emulsions under harsh environments.