Anti-abrasion collagen fiber-based membrane functionalized by UiO-66-NH2 with ultra-high efficiency and stability for oil-in-water emulsions separation

Membrane separation strategies offer promising platform for the emulsion separation. However, the low mechanical strength of membrane separation layers and the trade-off between separation flux and efficiency present significant challenges. In this study, we report a CFM@UiO-66-NH2 membrane with high separation flux, efficiency and stability, through utilizing a robust anti-abrasion collagen fiber membrane (CFM) as the multifunctional support and UiO-66-NH2 by an in-situ growth as the separation layer. The high mechanical strength of the CFM compensated for the weakness of the separation layer, while the charge-breaking effect of UiO-66-NH2, along with the size sieving of its constituent separating layers and the capillary effect of the collagen fibers, contributed to the potential for efficient separation. Additionally, the CFM@UiO-66-NH2 membrane exhibited superhydrophilic properties, making it suitable for separating oil-in-water microemulsions and nanoemulsions stabilized by anionic surfactants. The membrane demonstrated remarkable separation efficiencies of up to 99.960% and a separation flux of 370.05 L·m−2·h−1. Moreover, it exhibits stability, durability, and abrasion resistance, maintaining excellent separation performance even when exposed to strong acids and alkalis without any damage to its structure and performance. After six cycles of reuse, it achieved a separation flux of 417.97 L·m−2·h−1 and a separation efficiency of 99.747%. Furthermore, after undergoing 500 cycles of strong abrasion, the separation flux remained at 124.39 L·m−2·h−1, with a separation efficiency of 99.992%. These properties make it suitable for the long-term use in harsh operating environments. We attribute these properties to the electrostatic effect resulting from the amino group on UiO-66-NH2 and its in-situ growth on the CFM, which forms a size-screening separation layer. Our work highlights the potential of the CFM@UiO-66-NH2 membrane as an environmentally friendly size-screening material for the efficient emulsion wastewater separation.