Hydrophilic PAMAM dendrimer grafted Janus membrane for oil-water emulsion separation

Efficient separation of surfactant-stabilized oil-water emulsions remains a significant challenge. Janus membranes, featuring distinct chemical properties on opposite surfaces, have attracted considerable attention for emulsion separation applications. In this work, we report the fabrication of a Janus fiber membrane with a highly hydrophilic/underwater oleophobic polyethylene terephthalate (PET) side and a hydrophobic/underwater superoleophilic polyvinylidene fluoride (PVDF) side via electrospinning and chemical modification. Hydrophilic polyamidoamine (PAMAM) dendrimers were successfully grafted onto the PET side to achieve a wettability transformation. For the representative n-hexane systems, the PET-G3-facing configuration gave a permeance of 975 L⋅m −2 ⋅h −1 ·bar −1 and a separation efficiency of 96.9% for Hex/W emulsion, whereas the PVDF-facing configuration gave a permeance of 746 L⋅m −2 ⋅h −1 ·bar −1 and a separation efficiency of 99.5% for W/Hex emulsion. Also, the membrane achieved > 96.0% efficiency for Chl/W, Tol/W, Hex/W, and Hep/W emulsions, 91.6% for the Die/W emulsion, and > 99.0% for W/Hex, W/Hep, W/Tol, and W/Chl emulsions. Furthermore, the separation efficiencies remained above 96.9% and 98.0% after 10 continuous separation cycles for O/W (oil-in-water) and W/O (water-in-oil) emulsions. Additionally, after bovine serum albumin (BSA) protein contamination and simple water washing, the flux recovery rate (FRR) of this Janus membrane maintained 90.3%, demonstrating its strong anti-fouling properties. In summary, this study presents a sustainable and effective strategy for preparing Janus membranes using PET as a raw material, offering valuable insights into the separation of oil-water emulsions.