Molecular design of covalent−organic framework membranes for Li+/Mg2+ separation: Significant charge effect

Lyu, Bohui; Wang, Mao; Jiang, Jianwen; Jiang, Zhongyi

doi:10.1016/j.memsci.2022.120976

Cited by 22 publications

(10 citation statements)

References 48 publications

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“…Similarly, the COF membranes can also achieve a nearly 100% Mg 2+ rejection rate when the stacking number reaches 25 . For the system with an electric field of 0.6 V/nm, the Li + flux through the graphyne-3 membrane is 2.06 × 10 5 mol·m –2 ·h –1 , and the corresponding separation factor S Li/Mg is 27.46, which is remarkedly larger than the corresponding value for functionalized graphene nanopores and Tp-Tta-NH 3 + COF membranes, but lower than some positively charged polymer membranes. , Upon increasing the electric field to 1.0 V/nm, however, there is an increase in the Li + flux, but the separation factor decreases to 2.74. When it comes to the graphyne-4 membrane, it is observable from Figure b that both Li + and Mg 2+ can travel through the membrane regardless of the electric field intensity, and the transport numbers of Li + and Mg 2+ are larger than the counterpart for the graphyne-3 membrane.…”

Section: Resultsmentioning

confidence: 86%

“…Then the simulation box was filled with 0.5 M LiCl and a 0.5 M MgCl 2 mixture solution, and the details of the simulation system are listed in Table S2. Here, it should be mentioned that the choice of such a concentration is derived from previous experiments and simulations as they also employed the same concentration to investigate the Li + /Mg 2+ separation. ,,,− The schematic illustration of the simulation system is shown in Figure . The periodic boundary conditions were used in all three directions, and this allows us to mimic a continuous two-dimensional membrane.…”

Section: Simulation Models and Detailsmentioning

confidence: 99%

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Electric Field-Driven Ultraefficient Li⁺/Mg²⁺ Separation through Graphyne Membrane

Fang

Dai

et al. 2022

Ind. Eng. Chem. Res.

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The exploration of a new membrane material to achieve ultraefficient separation and recovery of Li + from salt lake brine is of tremendous importance in consideration of the soaring demand of the lithium resource. Here, we, by utilizing classical molecular dynamics simulations, investigated the selective separations of monolayer graphyne-3 and graphyne-4 membranes to Li + and Mg 2+ under applied electric fields. It is observed that the graphyne-3 membrane displays excellent Li + selectivity and permeability under the electric field of 0.4 V/nm, with Mg 2+ being completely rejected by the triangular nanopores of the graphyne-3 membrane. However, there is no preference for the graphyne-4 membrane to Li + and Mg 2+ since both ions can travel through the triangular nanopores of the graphyne-4 membrane, regardless of external electric field intensities. Our in-depth analysis uncovered that the thorough separation of the graphyne-3 membrane for Li + and Mg 2+ at an electric field of 0.4 V/nm is largely due to its dehydration difference in the second hydration shell. It is found that the dehydration numbers of water molecules around Mg 2+ are remarkedly less than the values needed for the ions to cross the nanopores, thus impeding Mg 2+ permeation. Besides, we noted that Li + tends to transport through the graphyne-3 nanopores via random positions, while the migration of Mg 2+ is concentrated in the central position. Our findings provide inspiration for the application of the graphyne-3 membrane in high-efficiency extraction and recovery of Li + from salt lakes.

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Section: Resultsmentioning

confidence: 86%

Section: Simulation Models and Detailsmentioning

confidence: 99%

Electric Field-Driven Ultraefficient Li⁺/Mg²⁺ Separation through Graphyne Membrane

Fang

Dai

et al. 2022

Ind. Eng. Chem. Res.

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“…Jiang and colleagues conducted a theoretical investigation into the transport mechanism of Li + and Mg 2 + ions across COF membranes under an electrodialysis operating mode, using COF membranes based on Tp and Tatp. [31] They further modified these membranes with different types of ionic sites, including À COOH, À COO À , and À NH 3 + . Simulation results indicated that membranes with positive charges exhibited the highest selectivity.…”

Section: Resource Extractionmentioning

confidence: 99%

“…Indeed, introducing positively charged sites on the pore walls of COF membranes proves beneficial for the separation of Li + and Mg 2+ ions. Jiang and colleagues conducted a theoretical investigation into the transport mechanism of Li + and Mg 2+ ions across COF membranes under an electrodialysis operating mode, using COF membranes based on Tp and Tatp [31] . They further modified these membranes with different types of ionic sites, including −COOH, −COO − , and −NH 3 + .…”

Section: Cof Membranes For Ion Separationmentioning

confidence: 99%

Function‐Led Design of Covalent‐Organic‐Framework Membranes for Precise Ion Separation

Meng,

Wu,

Wang

et al. 2023

Chemistry A European J

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Insufficient access to clean water and resources has emerged as one of the most pressing issues affecting people globally. Membrane‐based ion separation has become a focal point of research for the generation of fresh water and the extraction of energy elements. This Review encapsulates recent advancements in the selective ion transport of covalent organic framework (COF) membranes, accomplished by strategically pairing diverse monomers to create membranes with various pore sizes and environments for specific purposes. We first discuss the merits of using COF materials as a basis for fabricating membranes for ion separation. We then explore the development of COF membranes in areas such as desalination, acid recovery, and energy element extraction, with a particular emphasis on the fundamental principles of membrane design. Lastly, we address both theoretical and practical challenges, as well as potential opportunities in the targeted design of ion‐selective membranes. The goal of this Review is to stimulate future investigative efforts in this field, which is of significant scientific and strategic importance.

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“…Frontiers in Membrane Science and Technology frontiersin.org monovalent ions in water systems (i.e., sodium and chloride) has been targeted in many studies and applications (Lu et al, 2022). More recently, lithium recovery from salt-lake brines, which contain high magnesium concentration, has been studied extensively (Sun et al, 2015;Li et al, 2019, Li Q. et al, 2022Lyu et al, 2022). Efforts, therefore, mostly focus on maximizing the synergistic effect of size-and charge-based rejection by adjusting the membrane charge to be the same as the charge of the divalent ion (e.g., imparting a positive charge to the typically negative surface of polyamide membranes to enhance the removal of divalent cations) (Cheng et al, 2018).…”

Section: Separation Of Ions With Different Chargementioning

confidence: 99%

Intrinsic limitations of nanofiltration membranes to achieve precise selectivity in water-based separations

Epsztein

2022

Front. Membr. Sci. Technol.

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Over the last decades, nanofiltration (NF) membranes have been used to selectively remove certain solutes from water with recent interest targeting more challenging separations that require precise selectivity between solutes. In this perspective article, we aim to challenge (but not disprove) the prevalent notion that NF membranes are suitable for precise separations. We first provide and analyze selectivity data from the literature of three important separations including monovalent-divalent ion selectivity, separations involving organic molecules, and the more ambitious separations of ions with the same charge. We then introduce the terms rejection-based selectivity and transport-based selectivity to distinguish between the commonly “rough” separations pursued in NF (e.g., water softening) and the more visionary separations required for precise selectivity (e.g., transport of lithium through specific recognition sites), respectively. Using these terms, we discuss two major intrinsic limitations to achieve precise selectivity in NF systems; namely, the need for a solute-specific membrane that can transport simultaneously additional species (i.e., water and the complementary salt ion) and the detrimental effect of concentration polarization. We conclude with guidelines and principles to overcome these limitations.

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Molecular design of covalent−organic framework membranes for Li+/Mg2+ separation: Significant charge effect

Cited by 22 publications

References 48 publications

Electric Field-Driven Ultraefficient Li⁺/Mg²⁺ Separation through Graphyne Membrane

Electric Field-Driven Ultraefficient Li⁺/Mg²⁺ Separation through Graphyne Membrane

Function‐Led Design of Covalent‐Organic‐Framework Membranes for Precise Ion Separation

Intrinsic limitations of nanofiltration membranes to achieve precise selectivity in water-based separations

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Molecular design of covalent−organic framework membranes for Li+/Mg2+ separation: Significant charge effect

Cited by 22 publications

References 48 publications

Electric Field-Driven Ultraefficient Li+/Mg2+ Separation through Graphyne Membrane

Electric Field-Driven Ultraefficient Li+/Mg2+ Separation through Graphyne Membrane

Function‐Led Design of Covalent‐Organic‐Framework Membranes for Precise Ion Separation

Intrinsic limitations of nanofiltration membranes to achieve precise selectivity in water-based separations

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Electric Field-Driven Ultraefficient Li⁺/Mg²⁺ Separation through Graphyne Membrane

Electric Field-Driven Ultraefficient Li⁺/Mg²⁺ Separation through Graphyne Membrane