Hydrophilic modified ZIF-8 embedded two-dimensional vermiculite membrane for oil-water emulsion separation: Super-wettability, performance and mechanisms

With the increasing global water scarcity and people's increasing concern for the environment, the global demand for oily wastewater treatment continues to increase. As one of the most promising technologies, membrane treatment technology is widely used to treat oily wastewater. At present, two-dimensional material membranes are widely used for their unique structure and excellent properties. Here, this study developed a two-dimensional vermiculite (VMT) membrane using hydrophilic tannic acid-modified ZIF-8 (T-ZIF-8) as an intercalating agent to enhance the interlayer spacing and surface roughness of VMT. The optimized cellulose acetate (CA) membrane (T-ZIF-8@VMT/CA) was superhydrophilic and underwater superoleophobic (UWOCA>153°). This membrane achieved a water flux of 2.2 × 10³ L·m⁻² h⁻¹, representing a 20-fold enhancement over the VMT/CA membrane. The T-ZIF-8@VMT/CA membrane showed excellent separation efficiency (up to 99.4 %) for various of oil-in water-emulsions, as well as good separation efficiency (98.4 %) after 3 h long-term operation. Molecular dynamics simulations showed that the modification of T-ZIF-8 could effectively improve the interfacial demulsification and gravity-driven separation of emulsified oils. The T-ZIF-8@VMT/CA membrane had acid and alkali resistance, reusability, and antimicrobial properties. In conclusion, this study demonstrates that the proposed approach can simultaneously enhance water flux and separation effectiveness, showing promising potential for practical applications in real wastewater treatment.