Sodium alginate/poly(vinyl alcohol)/graphitic carbon nitride composite membrane with excellent anti-fouling properties for efficient oil-water separation

The oil spills and organic wastewater is a kind of environmental pollution which attracts widely concern. Membrane separation is a potential technology to settle these wastewaters. However, the high cost, the weak antifouling property, and the less functionality of the separation materials limit their promotion. In this work, the sodium alginate/polyvinyl alcohol/graphite-phase carbon nitride (PVA@SA@CN) hydrogel composite membranes were coated on the stainless steel mesh, and the double-network composite membrane was constructed. Results indicated that the PVA@SA@CN composite membrane is superhydrophilic/underwater superhydrophobic, and this composite presents excellent anti-fouling property. Oil-water separation experiments indicated that the separation efficiency was higher than 99 % even constitutively separated for 50 times, and the highest flux reached to 4.5 × 10 3  L·m −2 ·h −1 . In addition, the PVA@SA@CN composite membrane also presented exceptional self-cleaning ability. This research provides a new approach to the field of continuous oil-water separation.