Multi-Functional Membrane with Double-Barrier and Self-Cleaning Ability for Emulsion Separation: Fouling Model and Long-Term Operation

Abstract

Flux decay is the core factor that affects membrane performance and the long-term operation for emulsion separation. Herein, a double-barrier and multi-functional membrane for emulsion separation was fabricated via in-situ growth of MIL-88A on the Fe-phenolic network. This membrane performs enhanced anti-pollution ability of hydration layer and the self-cleaning ability of photo-Fenton catalysis to ensure high separation performance. Wettability and organic matter degradation performance of the membranes were experimentally determined. It could well implement emulsion separation (flux ~ 2602.55 LMH; separation efficiency ~ 99%) solely by gravity-driven. After a brief photo-Fenton catalysis, the water flux recovery ratios (FRR) of the membrane after 8 cycles (320 min) reach 94.87% (CTAB-stabilized emulsion) and 89.27% (SDS-stabilized emulsion), respectively. Interestingly, the flux and FRR of the membrane exhibit a negative relationship when it circularly filters different types of emulsion. Based on the Hermia models analysis, this difference mainly originates from that electrostatic repulsion assists in mitigating irreversible pollution while disfavors rapid demulsification and improving flux. The reverse was true when there was the opposite potential between the membrane surface and emulsions. Meanwhile, a novel optical transmission system is applied to transmit light in cloudy emulsion to achieve long-term operation (90 min).

Keywords: In-situ growth of MIL-88A, multi-functional membrane, oil-in-water emulsion, fouling model, long-term operation