Depositing of PVAM and GA onto PVDF/POTS-SiO2 to fabricate a Janus membrane for direct contact membrane distillation (DCMD).

The DCMD technology for wastewater treatment is very promising. However, it is easily suffered by membrane fouling and wetting. In this study, a Janus membrane was fabricated by coating polyvinylamine (PVAM) and gallic acid (GA) onto one side of a PVDF composite membrane, which another side is covered with POTS-SiO 2. The PVAM and GA side could bind water to form a hydration layer, thus repel the contaminants. The POTS-SiO 2 side was superhydrophobicity and prevented the membrane wetting. Finally, The Janus membrane presented exceptional performance in separating salt containing emulsified oil by DCMD. It kept a stable flux of 17.0 ± 0.2 Kg·m−2·h−1 and a low level conductivity of 0.60 ± 0.02 μS/cm in the cold side during the 36 h DCMD procedure, compared with the pristine PVDF membrane and the PVDF/POTS-SiO 2 membrane. The results presented simultaneously antifouling and antiwetting properties of the Janus membrane. While the Janus membrane can be well used in desalination of emulsified oil containing salt, it has a great potential for application to treat other complex wastewater. [Display omitted] • A Janus membrane was prepared via asymmetric modified process. • The Janus membrane presented simultaneous wetting resistant and antifouling performances. • The Janus membrane maintained stable flux and ultra-low conductivity in 36 h DCMD. • The Janus membrane showed great potential in treating complicated water or wastewater. [ABSTRACT FROM AUTHOR]