Metal-organic framework enables ultraselective polyamide membrane for desalination and water reuse

Wen, Yue; Dai, Ruobin; Li, Xuesong; Zhang, Xiaoyu; Cao, Xingzhong; Wu, Zhichao; Lin, Shihong; Tang, Chuyang Y.; Wang, Zhiwei

doi:10.1126/sciadv.abm4149

Cited by 116 publications

(53 citation statements)

References 85 publications

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“…As expected, the adoption of the free-interface strategy (RO-0.5, RO-1, RO-5, RO-10, and RO-60) successfully suppressed the formation of “ridge-and-valley” appearance that is typical for traditional IP (TFC), resulting in relatively smooth surfaces of the polyamide films. Similar low-roughness films have also been reported in the literature, ,, which has been attributed to the weakened local heating , and reduced confinement effect , during the IP reaction in the absence of a substrate. This relatively smooth surface morphology enables us to evaluate the evolution of the film thickness over time (Figure AFM).…”

Section: Resultssupporting

confidence: 86%

Unveiling the Growth of Polyamide Nanofilms at Water/Organic Free Interfaces: Toward Enhanced Water/Salt Selectivity

Zhou

Yang

et al. 2022

Environ. Sci. Technol.

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The permeance and selectivity of a reverse osmosis (RO) membrane are governed by its ultrathin polyamide film, yet the growth of this critical film during interfacial polymerization (IP) has not been fully understood. This study investigates the evolution of a polyamide nanofilm at the aqueous/organic interface over time. Despite its thickness remaining largely constant (∼15 nm) for the IP reaction time ranging from 0.5 to 60 min, the density of the polyamide nanofilm increased from 1.25 to 1.36 g cm–3 due to the continued reaction between diffused m-phenylenediamine and dangling acyl chloride groups within the formed polyamide film. This continued growth of the polyamide nanofilm led to a simultaneous increase in its crosslinking degree (from 50.1 to 94.3%) and the healing of nanosized defects, resulting in a greatly enhanced rejection of 99.2% for NaCl without sacrificing water permeance. Using humic acid as a molecular probe for sealing membrane defects, the relative contributions of the increased crosslinking and reduced defects toward better membrane selectivity were resolved, which supports our conceptual model involving both enhanced size exclusion and healed defects. The fundamental insights into the growth mechanisms and the structure–property relationship of the polyamide nanofilm provide crucial guidance for the further development and optimization of high-performance RO membranes.

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Section: Resultssupporting

confidence: 86%

Unveiling the Growth of Polyamide Nanofilms at Water/Organic Free Interfaces: Toward Enhanced Water/Salt Selectivity

Zhou

Yang

et al. 2022

Environ. Sci. Technol.

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“…Besides the removal of conventional inorganic salts, we also investigated the trace boron removal performance of the iCOFM. Boric acid (H 3 BO 3 ) is a kind of trace contaminant with only parts-per-million (ppm) concentration but widely exists in brackish water and usually requires energy-intensive membrane processes because of the low boron rejection by conventional synthetic membranes. − This low boron removal arises from the similar size between H 3 BO 3 and water (∼0.3 nm), while engineering membrane nanochannels smaller than H 3 BO 3 would sacrifice water permeance . Notably, H 3 BO 3 could be transferred to an ionic state B(OH) 4 – under weakly basic conditions .…”

Section: Resultsmentioning

confidence: 99%

Charged Nanochannels in Covalent Organic Framework Membranes Enabling Efficient Ion Exclusion

et al. 2022

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Controllable ion transport through nanochannels is crucial for biological and artificial membrane systems. Covalent organic frameworks (COFs) with regular and tunable nanochannels are emerging as an ideal material platform to develop synthetic membranes for ion transport. However, ion exclusion by COF membranes remains challenging because most COF materials have large-sized nanochannels leading to nonselective transport of small ions. Here we develop ionic COF membranes (iCOFMs) to control ion transport through charged framework nanochannels, the interior surfaces of which are covered with arrayed sulfonate groups to render superior charge density. The overlap of an electrical double layer in charged nanochannels blocks the entry of co-ions, narrows their passageways, and concomitantly restrains the permeation of counterions via the charge balance. These highly charged large-sized nanochannels within the iCOFM enable ion exclusion while maintaining intrinsically high water permeability. Our results reveal possibilities for controllable ion transport based on COF membranes for water purification, ionic separation, sensing, and energy conversion.

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“…This filtrationassisted controllable loading of hydrophilic MOFs provides a useful approach to fabricate TFN membranes with outstanding separation performance. Wen et al [30] developed a superselective polyamide (PA) membrane by enhancing the interfacial polymerization of amphiphilic MOF nanoflakes. The created ultrathin nanofilms had an intrinsic thickness of about 5 nm and a degree of crosslinking of about 98%.…”

Section: Cofmentioning

confidence: 99%

A Review of Advancing Two-Dimensional Material Membranes for Ultrafast and Highly Selective Liquid Separation

Zhang

Zheng

Yu³

et al. 2022

Nanomaterials

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Membrane-based nanotechnology possesses high separation efficiency, low economic and energy consumption, continuous operation modes and environmental benefits, and has been utilized in various separation fields. Two-dimensional nanomaterials (2DNMs) with unique atomic thickness have rapidly emerged as ideal building blocks to develop high-performance separation membranes. By rationally tailoring and precisely controlling the nanochannels and/or nanoporous apertures of 2DNMs, 2DNM-based membranes are capable of exhibiting unprecedentedly high permeation and selectivity properties. In this review, the latest breakthroughs in using 2DNM-based membranes as nanosheets and laminar membranes are summarized, including their fabrication, structure design, transport behavior, separation mechanisms, and applications in liquid separations. Examples of advanced 2D material (graphene family, 2D TMDs, MXenes, metal–organic frameworks, and covalent organic framework nanosheets) membrane designs with remarkably perm-selective properties are highlighted. Additionally, the development of strategies used to functionalize membranes with 2DNMs are discussed. Finally, current technical challenges and emerging research directions of advancing 2DNM membranes for liquid separation are shared.

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Metal-organic framework enables ultraselective polyamide membrane for desalination and water reuse

Cited by 116 publications

References 85 publications

Unveiling the Growth of Polyamide Nanofilms at Water/Organic Free Interfaces: Toward Enhanced Water/Salt Selectivity

Unveiling the Growth of Polyamide Nanofilms at Water/Organic Free Interfaces: Toward Enhanced Water/Salt Selectivity

Charged Nanochannels in Covalent Organic Framework Membranes Enabling Efficient Ion Exclusion

A Review of Advancing Two-Dimensional Material Membranes for Ultrafast and Highly Selective Liquid Separation

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