Transport across sub-nanometer zeolite pores for water desalination

The molecular sieving capability of zeolites, alumino-silicate minerals with 3-8 Å diameter pores, promises an efficient method to remove salt from seawater. In this work, we synthesized and characterized MFI zeolites with a nominal pore diameter of 5.6 Å with varying Si/Al ratio from 23 to infinity to alter the wetting properties. We subsequently performed pressure infiltration tests with the synthesized zeolites suspended in water to investigate the effect of wetting properties on water transport in the pores. Water sorption isotherms were obtained that show distinct infiltration stages of water transport. For MFI zeolites, pressures of over 100 MPa were needed to fill the pore volume. The insight gained from this work is a first step towards designing zeolite-based membranes for the active layer of a reverse osmosis membranes. This work will be further developed in future work to understand ion transport through zeolites.