Catalytic PVDF membrane for continuous reduction and separation of p-nitrophenol and methylene blue in emulsified oil solution

Removal of aromatic contaminants from water has been a challenge in the field of environmental remediation. In order to remove these contaminants efficiently, we developed a catalytic finger reactor based on PVDF membrane for continuous reduction of p-nitrophenol (4-NP) and methylene blue (MB) in chloroform-in-water emulsion by integration of physical sieving and chemical reaction. The catalytic finger reactor was elaborately constructed via the assembly of Au nanoparticles (AuNPs) inside the finger-like pores in PVDF membrane through a dynamic flow strategy by taking advantage of the pre-coated polydopamine layer. The wettability, morphological and distribution of AuNPs in the finger-like pores were revealed by contact angle, SEM and EDX. The prepared catalytic finger reactor reduced >99% of 4-NP (2.72 × 10−4 M) and MB (5.35 × 10−4 M) at a flow rate of 0.015 mL/cm2 s, corresponding to a residence time of 1.12 s and a linear velocity of 0.021 cm/s. Moreover, the catalytic PVDF membrane showed great reduction of 4-NP and high rejection to chloroform-in-water emulsion simultaneously in the continuous filtration process. Overall, the catalytic finger reactor realized the spontaneous and continuous reduction of 4-NP and MB in a flowing mode and as well as the emulsion separation.