Permeability-Selectivity Tradeoff of RO Membranes

Seawater desalination allows us to tap into a practically infinite reservoir to meet our water needs. Reverse osmosis (RO) is the most energy efficient seawater desalination technique. Efforts to advance the membrane selectivity, the ability to differentiate between different solutes and water, have been frustrated by the in complete understanding of the fundamental transport phenomena. To this end, we are studying the intrinsic transport mechanisms of reverse osmosis, specifically the permeability-selectivity tradeoff. In our recent study, we established the quantitative relationship between the tradeoff line and molecular diameter of the permeants, which reinforces the solution-diffusion framework for RO transport.