Natural systems developed for millions of years to evolve complex devices to translocate species across the cell membrane. Biological protein channels in natural membranes utilize highly selective pores to provide exceptional transport performances, in magnitudes far above those achieved by synthetic polymeric membranes used for desalination and water treatment. The nature should provide answers for efficient desalination.
Chemists have attempted to replicate natural systems by synthetically accessible and low-cost materials with an elegant combination of simplicity and utility. Biomimicking the proteins at molecular level is an important challenge. Similar impact of water conduction activity obtained with natural Aquaporins can be obtained by using simpler artificial compounds displaying transport functions like the natural ones. The first identification of Artificial water channels-AWCs in 2011, opened the door to new applicative desalination processes close to natural ones. We speculated at this time that biomimetic - AWCs might have timely important influences to increase this driving force for the transport by using natural principles and to change the water desalination paradigms:
- AWCs present robust and functional structures (2012), that selectively conduct water through bilayer membrane (2016).
- AWCs may provide a comprehensive understanding of the structures and mechanisms to effectively transport water in biological systems (2018).
- Straightforward synthetic availability of AWCs give rise to novel strategies towards the design of highly selective water transport membranes (2018).
The result of the fast-biomimetic transport of water through the AWCs might have high benefits and important practical applications like advanced desalination, or the production of ultrapure water for biomedical or electronic industry use or one-step purification of highly diluted solutions. The present results are related to important challenges in translating molecular transport properties to performant meter-scale membranes, thus filtration modules needed for effective desalination. We postulated that one of the creative strategies for addressing such scale-up challenges and to achieve improved performances, in terms of both permeability and selectivity, is to combine the polyamide, known for its scalability via the integration within a typical roll-to-roll processing system, with the highly permeable and selective AWCs. The key challenge in the construction of such hybrid material is the required adaptive interaction between polyamide chains and AWCs, preventing the formation of defects.
Herein, we report the incorporation of homogeneously packed AWC within a polyamide PA matrix, resulting in the production of scalable biomimetic membranes that remarkably outperform the classical TFC polyamide membranes in the treatment of highly saline feed streams. This study leads to a greater fundamental understanding of how AWC incorporation can be optimized at the nanoscale within low density hybrid AWC-PA sponge-like particles within PA matrix, to facilitate the ultrafast and highly selective transport of water, mainly occurring through channels, and to minimize the translocation of ions and molecules bypassing the membrane via defects. Differently to all other previous selective channels or materials reported in literature remain applicable in principle, the biomimetic membranes reported here are the first hybrid materials/composite membranes tested and applied under real seawater desalination conditions.
To read more about our work: M. Di Vincenzo, A. Tiraferri, V.-E. Musteata, S.Chisca, R.Sougrat, L.-B. Huang, S. P. Nunes, M. Barboiu Biomimetic artificial water channels membranes for enhanced desalination; Nat. Nanotechnol. 2020, DOI : 10.1038/s41565-020-00796-x; https://www.nature.com/articles/s41565-020-00796-x
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