Poly(vinylidene fluoride) membrane design for efficient oil-in-water emulsion separation: Integrating superhydrophilicity, photocatalysis and self-cleaning

To solve the increasingly serious wastewater problems, developing membranes with excellent filtration performance and anti-fouling property has been a research focus. Herein, hydrophilic tannic acid/cysteine/tyrosine@titanium (TA/Cys/Tyr@Ti) double crosslinked coating was constructed on the poly (vinylidene fluoride) (PVDF) microfiltration membranes by two-step coating method, while the mineralized titanium dioxide (TiO 2 ) nanoparticles were utilized to produce superhydrophilic membranes. The synergistic effect of the multilayered nanostructure and hydrophilic groups enables excellent underwater superoleophobicity and anti-fouling property of modified membranes. The addition of TiO 2 provides photocatalytic degradation and self-cleaning properties. The optimized modified membrane (MF-4) showed outstanding oil–water separation potential (emulsion flux of 2760 ± 30 L·m −2 ·h −1 , oil rejection rate of 99.5 ± 0.3 %) and stable recycling filter capacity. Moreover, MF-4 was able to efficiently degrade methylene blue under UV light, which was 99.1 % at 90 min. The flux recovery rate (FRR) was 97.4 % following simulated contamination and regeneration with bovine serum albumin. After UV irradiation, the FRR appeared to be significantly enhanced, proving its great anti-fouling and self-cleaning properties. This modified membranes with superhydrophilic and self-cleaning properties have great application potential in oily wastewater and achieving automatic operation of wastewater treatment.