Influence of Water Disinfection on Polyamide Membranes: Principles, Performances, and Perspectives

Aromatic polyamide (PA) thin-film composite membranes are widely employed in reverse osmosis and nanofiltration for seawater desalination and water reuse. However, they can be degraded by chlorine used in water disinfection for biofouling control, hampering operational efficiency and the membrane service life. Tremendous efforts have been made to mitigate the adverse impacts of water disinfection on PA membranes while maintaining biofouling control and filtration performance. This paper reviews the reaction mechanisms of PA membranes with various disinfectants (e.g., chlorine, bromine, chlorine dioxide, monochloramine, peracetic acid, and hydrogen peroxide). Mechanisms for their reactions with the PA membrane model monomer (e.g., benzanilide) include aromatic substitution, N-substitution, and amide bond breakage. In general, disinfectants with a high reduction potential would cause severe membrane damage. An increase in the surface halogen content upon chlorine disinfection can decrease PA membrane hydrophilicity. Yet, degradation of the membrane via an oxidation pathway typically increases its hydrophilicity. Mild oxidation enhances membrane salt rejection because of increasing surface negative charge and tightening effects, while severe oxidation leads to a decline in membrane performance. While summarizing the state of knowledge on the PA membrane performance after water disinfection, this review also identifies several knowledge gaps to highlight future research topics of interest.