Towards single-species selectivity of membranes with subnanometre pores

Epsztein, Razi; DuChanois, Ryan M.; Ritt, Cody L.; Noy, Aleksandr; Elimelech, Menachem

doi:10.1038/s41565-020-0713-6

Cited by 511 publications

(479 citation statements)

References 144 publications

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“…These solution-processable molecules can potentially be homogeneously processed into composite materials such as membranes using facile engineering methods for desalination applications. Considering their easily tunable window size and chemical nature, POCs are possible candidates for more directed and precise water separations such as solute–solute separation that can minimize desalination post-treatment 37 . Furthermore, the scaling-up ability of POC synthesis 38 can markedly reduce the materials cost for larger-scale applications.…”

Section: Resultsmentioning

confidence: 99%

Porous organic cages as synthetic water channels

et al. 2020

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Nature has protein channels (e.g., aquaporins) that preferentially transport water molecules while rejecting even the smallest hydrated ions. Aspirations to create robust synthetic counterparts have led to the development of a few one-dimensional channels. However, replicating the performance of the protein channels in these synthetic water channels remains a challenge. In addition, the dimensionality of the synthetic water channels also imposes engineering difficulties to align them in membranes. Here we show that zero-dimensional porous organic cages (POCs) with nanoscale pores can effectively reject small cations and anions while allowing fast water permeation (ca. 109 water molecules per second) on the same magnitude as that of aquaporins. Water molecules are found to preferentially flow in single-file, branched chains within the POCs. This work widens the choice of water channel morphologies for water desalination applications.

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Section: Resultsmentioning

confidence: 99%

Porous organic cages as synthetic water channels

et al. 2020

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“…Since the modifications can be controlled and fine-tuned, this line of investigation can lead to highly application-specific CDI systems. The modification of the electrode may be as simple as changing the activation conditions of a carbon electrode to obtain very narrow micropores, 41,42 by adding functional groups or resins with affinity towards specific species, 128,166 or even by modifying carbon electrodes with redox active organometallic polymers to remove organic ions. 109 In MCDI cells, selectivity may be also achieved by using or modifying ion-exchange membranes, e.g.…”

Section: Energy and Environmental Science Reviewmentioning

confidence: 99%

Recent advances in ion selectivity with capacitive deionization

Gamaethiralalage

Singh

Şahin

et al. 2021

Energy Environ. Sci.

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321

128

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“…Membranes with ultrahigh solute–solute selectivity are essential for high‐precision separation [ 1 ] with increased water recovery in desalination systems. Nanofiltration membranes have enormous use in water purification, [ 2,3 ] brine electrolysis, [ 4 ] production of high‐quality water, [ 5 ] smart water production for enhanced oil recovery in carbonate and sandstone reservoirs, [ 6 ] and the treatment of reinjected seawater to avoid sulfate scaling and prevent reservoir souring.…”

Section: Introductionmentioning

confidence: 99%

“…[ 7 ] Extensive research work has been conducted to increase the energy efficiency in the separation processes by reducing the thickness of the separation layer and thereby increasing the permeance of the membranes. [ 8–11 ] However, exceedingly high retention of specific ions and dissolved solutes is always imperative to achieve high efficiency [ 1,2,5,12 ] in the separation process. Thus, designing high‐specification nanofiltration membranes with performance beyond the permeance–selectivity upper‐bound of polymer membranes [ 13,14 ] is of primary importance to achieve both high selectivity and high permeance.…”

Section: Introductionmentioning

confidence: 99%

Ultraselective and Highly Permeable Polyamide Nanofilms for Ionic and Molecular Nanofiltration

Sarkar

Modak

Karan

2020

Adv Funct Materials

220

144

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Membranes with ultrahigh ion selectivity and high liquid permeance are needed to produce high-quality product water with increased recovery and process efficiency in water desalination. The narrow pore size distribution and controlled surface charge in the separation layer of nanofiltration membranes significantly improve the ion selectivity through molecular sieving and Donnan exclusion of co-ions. Here, the ultraselective and yet highly water permeable polyamide nanofilm composite nanofiltration membranes developed by precisely controlling the kinetics of the interfacial polymerization reaction by maintaining the stoichiometric equilibrium at the interface is reported. The kinetically favorable stoichiometric equilibrium condition prohibits the formation of aggregate pores in the nanofilm and leads to the formation of narrow network pores with a high surface negative charge. Nanofilms are designed with a controlled degree of crosslinking and made as thin as ≈7 nm to achieve increased water permeance. The ultraselective membranes exhibit up to 99.99% rejection of divalent salt (Na 2 SO 4) and demonstrate monovalent to divalent ion selectivity of >4000. The selectivity of these nanofilm composite membranes is beyond the permeance-selectivity upper-bound line of the state-of-the-art nanofiltration membranes and one to two orders of magnitude higher than the commercially available membranes with pure water permeances of up to 23 L m −2 h −1 bar −1. The fabrication process is scalable for membrane manufacturing.

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Towards single-species selectivity of membranes with subnanometre pores

Cited by 511 publications

References 144 publications

Porous organic cages as synthetic water channels

Porous organic cages as synthetic water channels

Recent advances in ion selectivity with capacitive deionization

Ultraselective and Highly Permeable Polyamide Nanofilms for Ionic and Molecular Nanofiltration

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