A sulfonated polydopamine coated-PVDF membrane development for oil/water separation via eco-friendly methodology

Here we report on the successful super-oleophobic membrane, a key approach to improving the reusable oil-water separation with high water flux abilities avoiding the critical drawbacks of super-oleophilic membranes such as oil-retention and low water flux. In the development, we used a durable hydrophilic-based PVDF membrane modified by sulfonated polydopamine via the in-situ polymerization method using an eco-friendly solvent, ethanol. In this study, an ultra-thin sulfonated polydopamine (SPD) layer was coated onto PVDF nanofiber creating PVDF-SPD by varying coating time for obtaining improved super-hydrophilic membrane. The final 24 h in-situ polymerized coated membrane, PVDF-SPD24h exhibited excellent oil/water separation performed with 36,000 Lm−2h−1 of water flux and 99% of separation efficiency. It remains at ∼97.8% of separation efficiency even after 30 filtration recycles with test mixture. In addition, the PVDF-SPD24h membrane also demonstrated relevant performance in harsh acid and alkaline media with less than 3 wt% of weight loss after 48 h of treatment at 80 °C. These results suggest that PVDF-SPD24h could be sustainable membrane for oily wastewater treatment purposes.