Critical role of water adsorption in the design of reverse osmosis membranes for simultaneous boron removal and salt rejection: insights from molecular simulations

YM Huang and MY Huang and Q Lyu and LC Lin, SEPARATION AND PURIFICATION TECHNOLOGY, 375, 133739 (2025).

DOI: 10.1016/j.seppur.2025.133739

The growing demand on clean water has led to a significant interest in advancing reverse osmosis (RO) technology with a particular focus on the discovery of novel membranes. Several highly-permeable nanoporous membranes have been reported with exceptional ability to reject salt ions or boron species. Membranes capable of removing both solutes however remain largely unexplored. To this end, molecular dynamics simulations are carried out to explore the design of membranes for their simultaneous removal. Notably, our findings reveal that employing the widely-adopted size-exclusion mechanism is not effective and exploiting the adsorption property of water in sub-nanoscale pores is instead the key. Specifically, preferentially adsorbed water can serve as a structural extension to the pore to sterically hinder boric acid for better boron removal. Meanwhile, their adsorption configuration, if strategically manipulated, can selectively disfavor the hydration of a specific type of ions to block the permeation of ion pairs for excellent salt rejection. Overall, this study provides new venues to the design of RO membranes.

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