Bio-inspired gas-entrapping membranes (GEMs) derived from common water-wet materials for green desalination

Ratul Das, Sankara Arunachalam, Zain Ahmad, Edelberto Manalastas, Himanshu Mishra

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Widespread stress on global water supplies compels the need for low-cost and sustainable desalination processes. In this regard, desalination through membrane distillation (MD) can harness waste-grade heat or renewable energy. So far, the membranes for MD have been exclusively derived from intrinsically water-repellant materials - mostly perfluorocarbons. However, perfluorocarbons are limiting in terms of operational conditions, and they also introduce economic and environmental concerns. The development of perfluorocarbon-free MD membranes would likely address those challenges. Here, we report on the proof-of-concept for biomimetic gas-entrapping membranes (GEMs) for MD derived from silica and poly(methyl methacrylate) (PMMA) that are water-wet materials. We drew inspiration for our GEM design from the cuticles of springtails and hairs of Halobates germanus, both of which exhibit mushroom-shaped (or reentrant) features. Accordingly, our GEMs comprise arrays of microscale cylindrical pores with reentrant inlets and outlets that can robustly entrap air on submersion in water. Our PMMA-GEMs yielded a vapor flux of J ≈ 1 L-m−2-h−1 while separating a solution of ∼0.6 M NaCl at 333 K from deionized water at 288 K under a cross-flow configuration. To our knowledge, this is the first-ever demonstration of MD membranes derived from intrinsically water-wet materials, and these findings suggest that the rational design of membranes towards greener and cheaper desalination processes is possible.
Original languageEnglish (US)
Pages (from-to)117185
JournalJournal of Membrane Science
Volume588
DOIs
StatePublished - Jun 16 2019

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