Enhancing properties of PSF membrane via a simple two-step coating of PDA and PVP for separating oil/water emulsions

Abstract

Background

Hydrophilic modification is a promising method to inhibit fouling formation on ultrafiltration membranes. Many relevant studies have been documented; however, most of these methods are either overly intricate or require costly chemicals, thus constraining their practical utility. In this work, we proposed a straightforward approach to modify a commercial polysulfone ultrafiltration membrane via a two-step coating process involving polydopamine (PDA) followed by polyvinylpyrrolidone (PVP). The influences of PVP molecular weight and concentration on the surface properties of the membrane were studied for oil/water emulsion treatment.

Results

Despite the fact that the introduction of a PVP layer adversely impacted the pure water permeability of the commercial membrane, its water flux during oil/water emulsion treatment was improved due to its improved antifouling properties, which can be attributed to a lower water contact angle. It was found that increasing the PVP concentration in the coating solution could improve the water flux and oil rejection during the treatment process. This enhancement is attributed to the augmented surface hydrophilicity combined with a reduction in membrane surface pore size. Additionally, the best-performing PVP-modified membrane exhibited significantly higher flux recovery rate, with its value for the second and third cycles at 89.4% and 80.4%, respectively, compared to the control membrane, which recorded 80.3% and 73.9%, respectively.

Conclusion

Modifying a membrane surface with PDA/PVP coating has been proven to enhance the surface wettability and antifouling properties significantly. These modifications led to improved oil removal efficiencies, demonstrating superior performance in oil/water emulsion treatment. © 2024 Society of Chemical Industry (SCI).