Are commercial polyamide seawater and brackish water membranes effectively charged?

• Salt permeability of polyamide RO membranes is invariant in a wide salinity range. The solution diffusion model adequately describes our seawater membranes. Membrane leaks may cause correlation between and observed salt permeability. New developments modeling solute transport reverse osmosis (RO) are based on the mechanistic description friction electromigration. In these models, membrane charge significantly impacts separation that occurs through Donnan partitioning. One implication strongly depends ion concentration feedwater. this study, we experimentally evaluate effect salinity, varied over almost two orders magnitude (ca. 10–650mM), four commercially available brackish water We found no significant feed permeability, while performance closely resembled specification by manufacturers. also demonstrate minor leak provides plausible alternative explanation to trend reported other studies. standard satisfactory data for feedwater conditions tested. .