Aminated superhydrophilic/underwater superoleophobic collagen fiber membrane for efficient separation of anionic surfactant-stabilized oil-in-water emulsions

Separating anionic surfactant-stabilized oil-in-water emulsions remains a critical challenge due to the presence of surfactants. In this study, we developed a unique collagen fiber-based CFM-PEI-TiO2 with superhydrophilic and underwater superoleophobic properties, enabling efficient separation of various anionic surfactant-stabilized oil-in-water microemulsions and nanoemulsions through charge demulsification effects. The membrane achieved high separation flux (1458.50 L·m−2·h−1) and separation efficiency (99.94%) simultaneously. Importantly, the membrane exhibited remarkable mechanical durability, as it remained capable of separating diverse oil-in-water emulsions even after being subjected to abrasion with sandpaper for 500 cycles, highlighting its long-term durability and economic viability. The robust membrane also demonstrated excellent recyclability, with a separation efficiency of over 99% after twelve cycles and a flux of 1299.10 L·m−2·h−1 after fifteen cycles. These properties can be attributed to the PEI-induced electrostatic interactions and the enhanced superhydrophilic-superoleophobic interaction provided by TiO2 on the unique collagen fiber membrane. The outcomes emphasize the versatility and potential of our membrane in overcoming the challenges associated with emulsified oily wastewater.