Flexible and mechanically robust polyimide foam membranes with adjustable structure for separation and recovery of oil-water emulsions and heavy oils

Oil-water separation materials have been widely studied, however, these materials are mainly used to separate light oil-water mixtures, and the application of heavy oil separation and recovery is rarely involved. It is urgent to develop novel multi-functional oil-water separation materials, especially for the separation membrane for heavy oil. Herein, mechanically robust fiber-reinforced fluorinated polyimide foam membranes (FPIFMs) with adjustable multistage pore structure and high oil-water selectivity were prepared by freeze-drying and surface modification. FPIFMs exhibit high tensile strength of 3.80 MPa with the synergistic effect of PI fibers and PAA . Besides, the macro void structure of the foam membrane can be precisely adjusted to achieve the separation of different types of oil-water mixtures, oil-water emulsions, especially the separation and recovery of heavy oil. The results show that the foam membranes can separate light oil (26935L·m −2 ·h −1 ), oil-water emulsion (364L·m −2 ·h −1 ) and heavy oil (30L·m −2 ·h −1 ) under gravity. This stable, highly flexible, highly efficient and reusable foam membrane is an attractive option for oil spill treatment and wastewater purification.