Guandong-candy-inspired electrolessly welded composite polyvinylidene fluoride (PVDF) membranes with self-cleaning and recyclable properties for efficient oil-in-water emulsion separation

Abstract

Recently, oily wastewater has become an urgent cross-regional problem. Membrane technology is considered a sound solution to this crisis. However, membrane fouling causes a sharp decrease in water permeance and service life, which greatly restricts membrane applications. In addition to a few degradable materials, the most severely polluted membranes are burned or buried in the soil, wasting resources and accelerating ecological damage. Inspired by Guandong candy, we reported a novel, facile, and green approach to construct composite polyvinylidene fluoride (PVDF) membranes with stable self-cleaning, anti-oil-fouling, and photocatalytic recovery properties for efficient oil-in-water emulsions separation. Due to the synergistic effect of the superhydrophilic tin dioxide/titanate nanotubes (SnO2/TNTs) and Guandong-candy-inspired electrolessly welding organic–inorganic hybrid colloids, the composite PVDF membrane showed remarkable stability and underwater oil-repellency properties. Accordingly, the composite PVDF membrane achieved excellent water permeance (>2600 L m−2 h−1 bar−1), superior separation efficiency (>99.6 %), and long-term antifouling performance during soybean oil-in-water emulsion separation. More importantly, the composite PVDF membrane exhibited highly efficient self-cleaning and recovery of the PVDF membrane and SnO2/TNTs under visible-light irradiation. Within the framework of green and sustainable concepts, this is a novel reusable idea for the recyclable utilization of commercial PVDF membranes and photocatalytic minerals in oily wastewater purification.