Preparation of underwater superoleophobic ZIF-67 composite membrane with high antibacterial activity and emulsion separation efficiency

Bacteria and oils can be found in domestic sewage and wastewater from biomedical industries, however, traditional membranes have limitation in bacterial resistance, so it is high demand to design oil-water separation membranes with antibacterial activity. In this work, a novel TCN-ZIF-67/PVA@NM composite membrane with underwater superoleophobic property was prepared by in-situ growth method. The effects of ZIF-67 on emulsion separation and antibacterial activity were investigated in details. Results show that TCN-ZIF-67/PVA@NM have high separation efficiencies for oil-in-water emulsions stabilized by SDS, CTAB or Tween 80. Due to the positive charge of ZIF-67, the separation flux shows a trend of SDS>CTAB>Tween 80. The separation efficiency and antibacterial activity of the composite membrane increased and the separation flux decreased with the increase of the particle size of ZIF-67. In addition, the composite membrane had good inhibitory effects against the biofilm formation of S. aureus and MASR. It was found that when the reaction time was more than 6 h, the separation efficiencies of oil-in-water emulsions were more than 99%, and the bacterial inhibition ratios against S. aureus and E. coli. and biofilm inhibition ratios against S. aureus and MASR were more than 90%. When separating the emulsion containing bacteria, the composite membrane can simultaneously purify the emulsion and kill the bacteria in the water. Overall, ZIF-67 plays key roles in both emulsion separation and bacterial resistance, and the ZIF-67 composite membrane shows a promising potential in oil-water emulsion separation application.