Tunning the Wettability of the PVDF Membrane using the PVA-Stabilized TA-UiO-66-NH MOF Membranes to Separate Layered Oil-Water Mixture and Surfactant-Stabilized Emulsion.

This study introduces a UiO-66-NH/Tannic acid/Polyvinylidene fluoride (UTP) composite membrane for efficient oil-water separation. Pristine polyvinylidene fluoride (PVDF) membranes, due to their hydrophobic nature, tend to foul during oil-in-water emulsion separation. By incorporating the metal-organic framework (MOF) UiO-66-NH and stabilizing it with tannic acid (TA) and polyvinyl alcohol (PVA), the membrane's hydrophilicity and antifouling properties were significantly enhanced. The water contact angle of the UTP membrane decreased from 121° to 3°, indicating a dramatic increase in hydrophilicity, while the underwater oil contact angle (UWOCA) of 119° demonstrated excellent oleophobicity. The modified membrane achieved over 99 % separation efficiency and improved flux by 15 times compared to the pristine PVDF. TA acted as a binder, ensuring uniform MOF dispersion and improving the composite's stability. The PVA further reinforced the structure, enhancing durability under operational conditions. Durability tests showed no significant MOF detachment after repeated use, confirming the stability of the UTP composite. The results highlight the potential of the UTP membrane for oil-water separation with superior permeability and fouling resistance.