Hydration of salts as a two-step process: Water adsorption and hydrate formation

Sögütoglu, Leyla; Birkelbach, Felix; Werner, Andreas; Fischer, Hartmut; Huinink, H.P.; Adan, O.C.G.

doi:10.1016/j.tca.2020.178819

Cited by 38 publications

(32 citation statements)

References 34 publications

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“…The presence of water at the surface creates a disordered MgCl 2 region; consequently, H 2 O molecules are also loaded within the salt itself. This fluidized nucleation process is according to the twostep hydration process formulated by Soguẗoglu et al 6,7 The given results from the biased ReaxFF−GCMC algorithm validate the potential of the method for future studies. For example, to use it for complex TCM (e.g., encapsulated, impregnated, double, doped, or mixed salts) for which thermodynamic values are not available in the literature.…”

Section: Discussionmentioning

confidence: 57%

“…This effect reappears in the hydration of the MgCl 2 clusters, where the added water creates a disordered MgCl 2 •nH 2 O cluster that allows further hydration within the created voids of the disordered structure. This is according to the hypothesized theory of a two-step hydration process by Soguẗoglu et al 6,7 in which the complete hydration process of a salt is described by two distinctive steps; step (1) water adsorption from the atmosphere to a wetting layer on the surface of the salt and accordingly dissolution of ions; step (2) nucleation into the crystal of the final hydrate. This second step, the nucleation of a crystal, is a rare event which occurs on time scales far beyond MD time scales.…”

Section: Hydration Of Mgclmentioning

confidence: 95%

“…i n ins RxFF ig bias, (7) where E RxFF is the energy difference between the new and old configurations by ReaxFF. For the deletion of a molecule from the system, the Rosenbluth weight of the old configuration has to be computed, which is done by performing k − 1 random insertion trial positions, and the kth position is the old configuration itself…”

Section: Methodsmentioning

confidence: 99%

“…The operation of the thermochemical energy storage is dictated by the given equilibrium conditions of the reaction as described by thermodynamics. 6,7 Ideal thermochemical materials (TCMs) for such storage require high reaction energies between the sorbate and sorbent, stability over many storage cycles, and a reaction equilibrium around desired operating temperatures and partial pressures of the sorbate. Salt hydrates are promising TCMs 8−10 for applications in the built environment because of the high sorption energy of water vapor and dehydration conditions, which are reachable by built environment climate systems.…”

Section: Introductionmentioning

confidence: 99%

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Reactive Grand-Canonical Monte Carlo Simulations for Modeling Hydration of MgCl₂

Heijmans

Tranca

Chang³

et al. 2021

ACS Omega

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Thermochemical heat-storage applications, based on the reversible endo-/exothermic hydration reaction of salts, are intensively investigated to search for compact heat-storage devices. To achieve a truly valuable storage system, progressively complex salts are investigated. For these salts, the equilibrium temperature and pressure conditions are not always easy to predict. However, these conditions are crucial for the design of thermochemical heatstorage systems. A biased grand-canonical Monte Carlo (GCMC) tool is developed, enabling the study of equilibrium conditions at the molecular level. The GCMC algorithm is combined with reactive force field molecular dynamics (ReaxFF), which allows bond formation within the simulation. The Weeks−Chandler− Andersen (WCA) potential is used to scan multiple trial positions for the GCMC algorithm at a small cost. The most promising trial positions can be selected for recomputation with the more expensive ReaxFF. The developed WCA−ReaxFF−GCMC tool was used to study the hydration of MgCl 2 •nH 2 O. The simulation results show a good agreement with experimental and thermodynamic equilibriums for multiple hydration levels. The hydration shows that water, present at the surface of crystalline salt, deforms the surface layers and promotes further hydration of these deformed layers. Additionally, the WCA−ReaxFF−GCMC algorithm can be used to study other, non-TCM-related, reactive sorption processes.

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Section: Discussionmentioning

confidence: 57%

Section: Hydration Of Mgclmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Reactive Grand-Canonical Monte Carlo Simulations for Modeling Hydration of MgCl₂

Heijmans

Tranca

Chang³

et al. 2021

ACS Omega

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“…And the adsorption has been proved to have negligible contributions to the overall sorption process. [52][53][54] Although the high hygroscopicity of salts is attractive for AWH, some critical drawbacks restrict their practical use. For example, the deliquescence can cause salt particle aggregations and suppress the absorption kinetics, leading to a decreased performance in the following cycles.…”

Section: Hygroscopic Salts-based Atmospheric Water Harvestingmentioning

confidence: 99%

Materials Engineering for Atmospheric Water Harvesting: Progress and Perspectives

et al. 2022

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require substantial centralized infrastructures and frequent maintenance, which can prevent their implementation in some developing or rural areas. [10] Therefore, alternative freshwater generation technologies are necessary, especially in those land-locked nations and arid regions. The ubiquitous atmosphere contains ≈12 900 cubic kilometers of water vapor, which is a valuable source of freshwater. In this regard, extracting water from the air, that is, atmospheric water harvesting (AWH), becomes a promising alternative technology to produce freshwater in the absence of centralized facilities and without regional restrictions. [11,12] AWH can be achieved through three different approaches: fog collection, dew harvesting, and sorbent-based AWH. Fog collection technology directly harvests tiny water droplets in the air without the need of electricity. [13] However, it requires the existence of fog, which is only applicable in coastal or mountainous regions. [14] Another straightforward method to achieve AWH in a broader geographic range is to create the dew point (the temperature at which the air is saturated with water vapor) using dehumidification equipment with cooling components, that is, the dew harvesting. [15] However, cooling the air below its dew point consumes enormous energy and causes low energy efficiency, especially in those hot and dry areas. [16] To overcome these challenges, sorbent-based AWH was developed to spontaneously capture the free water molecules in the air via adsorption or absorption. [17][18][19] The interaction between water and sorbents leads to the cooling-free water condensation. For example, metal-organic framework (MOF)-based materials can capture water molecules from an arid environment with a relative humidity lower than 30% without cooling accessories. [20] To enhance the performance of AWH technologies, it is essential to first understand the fundamental process of AWH. The core of AWH is to extract free water molecules or tiny water droplets from the air and turn them into fresh bulk water, that is, to manage the evolution of water. Specifically, taking advantage of materials engineering tools to tailor the water-materials interactions, various water evolution processes (Figure 1), such as, rapid droplet nucleation (for dew harvesting), fast droplet growth, and efficient droplet departure (for fog/dew harvesting), effective vapor capturing and energy-efficient water release (for sorbent-based AWH), can be realized to facilitate the AWH. For example, the integration of a hydrophilicity-switchable polymer Atmospheric water harvesting (AWH) is emerging as a promising strategy to produce fresh water from abundant airborne moisture to overcome the global clean water shortage. The ubiquitous moisture resources allow AWH to be free from geographical restrictions and potentially realize decentralized applications, making it a vital parallel or supplementary freshwater production approach to liquid water resource-based technologies. Recent advances in regulating chemical properties an...

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Investigation into the Hydration Behavior of K2CO3 Packed Beds: An NMR Study

Raemaekers

Donkers²,

Huinink

2023

Transp Porous Med

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K2CO3 is seen as a promising heat storage material, available for applications in the domestic sector. For practical purposes, the material is hereby often employed in a packed bed containing millimeter-sized particles. To gain more insight into the hydration behavior of these packed beds, quantitative NMR measurements, capable of following the in-situ hydration behavior, are presented for the first time. It is found that hydration behavior varies significantly, depending on the specific hydration conditions that are chosen. At low airflows hydration is found to proceed via a hydration front, while higher airflows cause the hydration front to widen. Since an increase in flow rate coincided with an increase in the supplied water vapor, hydration is eventually found to proceed in a uniform manner. A comparison between TGA and NMR measurements shows that the overall packed bed hydration kinetics hereby transition to the reaction kinetics of single K2CO3 particles. Graphical Abstract

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Hydration of salts as a two-step process: Water adsorption and hydrate formation

Cited by 38 publications

References 34 publications

Reactive Grand-Canonical Monte Carlo Simulations for Modeling Hydration of MgCl₂

Reactive Grand-Canonical Monte Carlo Simulations for Modeling Hydration of MgCl₂

Materials Engineering for Atmospheric Water Harvesting: Progress and Perspectives

Investigation into the Hydration Behavior of K2CO3 Packed Beds: An NMR Study

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Hydration of salts as a two-step process: Water adsorption and hydrate formation

Cited by 38 publications

References 34 publications

Reactive Grand-Canonical Monte Carlo Simulations for Modeling Hydration of MgCl2

Reactive Grand-Canonical Monte Carlo Simulations for Modeling Hydration of MgCl2

Materials Engineering for Atmospheric Water Harvesting: Progress and Perspectives

Investigation into the Hydration Behavior of K2CO3 Packed Beds: An NMR Study

Contact Info

Product

Resources

About

Reactive Grand-Canonical Monte Carlo Simulations for Modeling Hydration of MgCl₂

Reactive Grand-Canonical Monte Carlo Simulations for Modeling Hydration of MgCl₂