Ultra-high flux and synergistically enhanced anti-fouling Ag@MXene lamellar membrane for the fast purification of oily wastewater through nano-intercalation, photocatalytic self-cleaning and antibacterial effect

Abstract

The membrane fouling from oils, soluble organic matters, and microorganism is inevitable in practical application of oil/water separation, which easily causes the decline in flux and service life of membrane. Therefore, developing the advanced separation membrane with high flux and anti-fouling feature is still a big challenge. Herein, we report a facile strategy to prepare the multifunctional Ag@MXene/PEN fibrous composite membrane by the self-assembly of Ag@MXene hybrid on electrospun poly (arylene ether nitrile) (PEN) porous support. In the hierarchical skin layer of fibrous composite membrane, the silver nanoparticles (AgNPs) were anchored onto the MXene surface via the self-reduction of silver nitrate, in which the MXene acted as reductant. Meanwhile, the Ag@MXene hybrid was stabilized and modified by the bio-inspired dopamine triggered crosslinking with polyethyleneimine. Because of regulated interlayer spacing, super-hydrophilic property, and porous supporting layer, the Ag@MXene/PEN fibrous composite membrane exhibited the ultra-high permeance (up to 11957.5 L·m−2·h−1·bar−1) for different oil–water emulsions while maintaining high-level rejection rate (99.13%), which was far beyond other MXene-based composite membranes reported before. Moreover, the fibrous composite membrane showed the satisfactory photocatalytic degradation rates for the methyl orange (15 ppm, 95.24%) and crystal violet (15 ppm, 95.61%) in 60 min, demonstrating the photocatalytic self-cleaning ability for organic pollutants. In addition, the fibrous composite membrane exhibited ∼ 99.99% E. coli growth inhibition, achieving the favorable antibacterial effect. Therefore, the low oil adhesion, photocatalytic self-cleaning, and antibacterial effect contributed to the synergistically enhanced anti-fouling, which enabled the membrane material to maintain high separation efficiency and long-term usage in complex multi-pollutant environments. The combination of high permeability and enhanced anti-fouling performance makes the fibrous composite membrane an ideal candidate for the fast purification of emulsified oily wastewater.