Study on the permeability-selectivity tradeoff in reverse osmosis membranes is accepted for publication in Water Research!

May 29, 2021

Our research article examining the influence of solute molecular size on the permeability-selectivity tradeoff in reverse osmosis has been accepted for publication in Water Research!

Reverse osmosis (RO) is widely deployed in water purification applications, including desalination and wastewater reclamation, but current understanding of the membrane transport mechanisms is still incomplete. Our study investigates the underlying factors governing the intrinsic tradeoff between water permeability and solute selectivity. By analyzing the transport of various nonelectrolyte solutes across thin-film composite polyamide membranes, we found that the slopes and intercepts of the tradeoff lines can be quantitatively related to the solute and water diameters, consistent with the solution-diffusion (S-D) framework for gas separation membranes. Additionally, a transport regime where solute permeation is weakly dependent on water transport is identified for the first time. The analysis further quantified the principal role of solute size in governing RO transport in the two regimes. Findings of this study provide new insights for understanding the transport mechanisms in osmotic membrane processes.