Nafion-Based Low-Hydration Polyelectrolyte Multilayer Membranes for Enhanced Water Purification

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Micropollutant contamination in water poses risks to ecosystems and human health.
• Conventional wastewater treatment struggles to remove emerging contaminants like pharmaceuticals and plasticizers.
• Polyelectrolyte multilayer (PEM) membranes offer a promising solution due to their stability and tunable properties.

Purpose of the Study:

• To enhance the rejection of small, difficult-to-remove micropollutants using PEM membranes.
• To investigate the effect of incorporating Nafion as a final layer on PEM membrane structure and performance.
• To develop advanced membranes for improved water purification.

Main Methods:

• Fabrication of PEM membranes using poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS).
• Application of a final Nafion layer to modify PEM membrane density and swelling.
• Construction of additional Nafion/PAH layers to further decrease the molecular weight cutoff (MWCO).
• Testing membrane performance using a cocktail of eight low-molecular-weight micropollutants (200-650 Da).

Main Results:

• Terminating PEM membranes with Nafion reduced multilayer swelling by 50%.
• Nafion incorporation led to a lower MWCO and increased hydraulic membrane resistance.
• PSS/PAH/Nafion-based multilayers demonstrated high rejection rates for challenging micropollutants.
• Up to 97% removal of a mixed micropollutant cocktail was achieved.

Conclusions:

• Nafion-modified PEM membranes significantly improve the removal of low-molecular-weight micropollutants.
• The enhanced membrane structure allows for superior water purification capabilities.
• These advanced membranes represent a breakthrough in tackling water contamination from emerging pollutants.