Zwitterionic Coatings Enhance Antifouling Properties of Reverse Osmosis Membranes

Strategic Insights -

Scientists have developed a novel approach to enhance the antifouling properties of reverse osmosis (RO) membranes using zwitterionic coatings synthesized via initiated chemical vapor deposition (iCVD). The researchers, led by R. Yang from the Massachusetts Institute of Technology, created a zwitterionic structure by reacting poly[2-(dimethylamino)ethyl methacrylate-co-ethylene glycol dimethacrylate] (PDE) thin films with 1,3-propane sultone. The cross-linker ethylene glycol dimethacrylate (EGDMA) was used to make the copolymer insoluble in water. The zwitterionic coatings were then covalently grafted onto RO membranes, which showed superior antifouling performance compared to bare RO membranes.

Key Takeaways:

  • The researchers created a zwitterionic structure by reacting PDE thin films with 1,3-propane sultone, resulting in a copolymer with charged zwitterionic moieties.
  • The zwitterionic coatings were synthesized via iCVD, a process that allows for the deposition of thin films at low temperatures, preserving the delicate structure of the RO membranes.
  • The zwitterionic coatings were conformal and smooth over the RO membrane, as revealed by scanning electron microscope (SEM) and atomic force microscope (AFM).
  • The coating thickness was measured using ellipsometry, and the salt rejection was not impaired by the coating.
  • Permeation tests revealed a 15% to 43% reduction in permeation under different feed pressures, film thicknesses, and film compositions.
  • Cell adhesion tests using Escherichia coli showed that the coated RO membranes exhibited superior antifouling performance compared to the bare RO membrane.

Statistics:

  • Thickness of the zwitterionic coatings measured by ellipsometry: not provided
  • Reduction in permeation: 15% to 43%
  • Number of feed pressures tested: not provided
  • Number of film thicknesses tested: not provided
  • Number of film compositions tested: not provided

Sources:

  • Yang, R., et al. (2011). Surface-Tethered Zwitterionic Ultrathin Antifouling Coatings on Reverse Osmosis Membranes by Initiated Chemical Vapor Deposition. Chemistry of Materials, 23(5), 1263-1272.
  • Chemistry of Materials. (Publisher). American Chemical Society, 1155 16th St., NW, Washington, DC 20036, USA.