Water Desalination Using Porous Organic Cage Membranes: A Simulation Exploration

With a comparatively low energy cost^[1], reverse osmosis (RO) is estimated to account for 53% of the global water desalination capacity^[2]. The cost and performance of RO processes is largely determined by the membrane used, which is primarily characterized by easy preparation, high water flux and high salt selectivity^[3]. Porous organic cages (POC)^[4], organic molecules with intrinsic cages, can be processed easily due to their solubility in common organic solvents. Their water stability^[5] further provide the opportunity of being utilized in RO processes. In this work, we report the first proof-of-concept simulation study on the potential of a series of POCs, both crystalline and amorphous, as RO membranes for water desalination. It is revealed that the channel size and topology of POCs are two dominant factors governing desalination performance. One POC crystal, CC2, with straight channels running through the membrane, possesses a high water permeability of 2.05×10^-6 kg/(m²∙hr) and 100% salt rejection. These findings from the bottom-up may guide the design and preparation of POC-based membranes for high-performance water desalination.

References

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