Layer-by-layer construction of super-hydrophilic and self-healing polyvinylidene fluoride composite membrane for efficient oil/water emulsion separation

For the efficient treatment of oily wastewater, fabrication of super-wetting polymer membrane with self-healing property is promising strategy. In this work, we developed a facile method to prepare highly efficient and self-healing polyvinylidene fluoride (PVDF) composite membrane for the oil/water emulsion separation. To achieve this goal, the thin hydrogel layer was constructed on polyacrylic acid grafted PVDF (PAA-g-PVDF) filtration membrane through layer-by-layer (LBL) self-assembly of sodium alginate, chitosan, and Fe3+. Benefiting from the strong hydrogel feature, the obtained PVDF composite membrane exhibited super-hydrophilic (Water contact angle: 0°) and underwater ultralow-oil adhesive super-oleophobic property (Under water contact angle: up to 169.6°). As a result, the obtained PVDF composite membrane exhibited high separation efficiency for various oil/water emulsions, with the separation flux of 974 L·m−2h−1 (0.04 MPa) and rejection ratio of 99.21% at room temperature. In addition, the composite membrane exhibited good recycling performance and stability in corrosive conditions (1 M NaOH, 0.5 M HCl and 2 M NaCl). Moreover, the PVDF composite membrane possessed good anti-fouling performance and certain self-healing ability. Therefore, this work provided an alternative way to prepare high-performance composite membrane with super-hydrophilic and self-healing property, showing potential application for the oily wastewater treatment.