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

Abstract

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.