Facile fabrication of 2D MOF-Based membrane with hierarchical structures for ultrafast Oil-Water separation

The surface chemical composition and building unit structures of membrane are the key factors to realize highly-efficient oil–water separation. Here we report the synthesis of Cu-CAT-1 metal–organic frameworks (MOFs) with unique two-dimensional (2D) hierarchical structures grown directly on copper mesh (Cu-CAT-1@CM) for oil–water separation. The Cu-CAT-1@CM membrane with micro/nano- architecture exhibits robust superhydrophilicity and underwater superoleophobicity characteristics, allowing gravity-driven oil–water separation by achieving ultrahigh flux up to 329 kL∙m⁻²∙h⁻¹. The membrane shows excellent separation performances by testing various oils, particularly actual crude oil and xylene, which are considered as the notorious pollutants in the water. The residual oil contents of six samples are all less than 24.6 mg∙L^-1. The mechanism analysis demonstrated that the appropriate hierarchical structures of the membrane surface is the code for the extreme wettability that remarkably improved the separation efficiency. Moreover, such a membrane with high performance can be readily synthesized by electrochemical method at room temperature in only 20 min, which shows the advantages of facile and environmentally friendly fabrication process as well as low cost. Overall, the membrane with energy-saving of gravity-driven and ultra-high permeability allows the rapid separation of oil–water mixture, showing the potential applications for resolving the problem of oil pollution.