A computational study of water in UiO‐66 Zr‐MOFs: Diffusion, hydrogen bonding network, and confinement effect

Abstract

For chemical warfare agent removal, the humidity emerges as an unavoidable challenge that significantly affects the performance of metal-organic frameworks. In this work, via density functional theory calculations, ab initio molecular dynamics and classical molecular dynamics simulations, we investigate the structural and diffusion properties of water in the pristine defect-free UiO-66, one Zr-based metal-organic framework. Through the detailed analyses of the distribution probability of water in two different cages of UiO-66, the binding interaction between water and UiO-66, the hydrogen bonding networks and resulted localized water clusters, we gain a fundamental understanding of structural and dynamics properties as well as the concentration dependence of water in UiO-66. We anticipate those theoretical results could provide insight to the competitive adsorption of water and chemical warfare agents, which eventually shows the utmost importance for the design and development of the next generation porous materials with appropriate water properties in real-life applications.

Modelling drug adsorption in metal–organic frameworks: the role of solvent

“…This higher adsorption in experiments can be attributed to the stronger interaction of the carboxylic group with the defect sites on the zirconium nodes of the UiO-AZB in our experiments. 51,52 Similarly, the adsorption of 5-FU and HU in the exterior pores was 8.59 and 72.86 molecules accounting for 121.92 mg g À1 and 605.41 mg g À1 . Thus, the adsorption of 5-FU and HU is within 2% and 110% to that of experimentally measured adsorption, respectively.…”

Mass transfer behavior of methane in porous carbon materials

“…The adsorption capacity and diffusion coefficient affect the release flow of methane. In MD simulation, the diffusion mechanism is probed by the scaling factor between MSD and diffusion time: where z ( t ) represents the displacement of fluid molecules at time t ; square parentheses denote the ensemble average, and α represents the diffusion mode: fluids diffuse in single‐file, Fickian, and ballistic modes, taking α values of 0.5, 1.0, and 2.0, respectively 49,50 . We have rechecked that the α value for CH 4 in porous carbon adsorbents is 1.0, which represents the Fickian diffusion mode.…”

“…where z(t) represents the displacement of fluid molecules at time t; square parentheses denote the ensemble average, and α represents the diffusion mode: fluids diffuse in single-file, Fickian, and ballistic modes, taking α values of 0.5, 1.0, and 2.0, respectively. 49,50 We have rechecked that the α value for CH 4 in porous carbon adsorbents is 1.0, which represents the Fickian diffusion mode. In the case of Fickian diffusion, Einstein's equation can be applied for the calculation of the self-diffusion coefficient by calculating the MSD and selfdiffusion coefficient: 51…”

Capture of Toxic Oxoanions from Water Using Metal–Organic Frameworks

“…Oxoanions are a class of pollutants of increasing concern resulting from various industrial processes prevalent today. When discharged into bodies of water, their inherent toxicity harms ecosystems and contaminates potable water. , Oxoanions have been classified as toxic priority pollutants under the Clean Water Act, and because tolerable concentrations are often exceeded, targeted treatment of affected bodies of water becomes necessary. , Several treatment mechanisms have been developed to remediate water sources from these pollutants ranging from the facilitation of degradation processes and use of activated carbon capture to the deployment of sorbents (such as metal–organic and covalent–organic frameworks) for explicit removal of oxoanions. − The latter approach is the focus of this investigation, for which high capacity, porous materials including metal–organic frameworks (MOFs) have found efficient implementation as sorbents. ,− MOFs (nanoporous crystalline materials consisting of metal clusters linked together by organic ligands) exhibit tunable pore sizes, easily functionalizable ligands, and high internal surface areas, making them ideal candidates for small molecule capture and separation. − The vast combinations of metal nodes and organic ligands allow for tuning the chemical and physical properties of MOFs to highly specific applications . This flexibility has led to a wide range of MOF designs, such as zeolitic imidazolate frameworks (ZIFs), cationic MOFs, and neutral MOFs containing open-metal sites. − MOFs hold much promise as highly selective next-generation sorbents by virtue of their diverse structures and finely tunable host–guest interactions.…”

“…1,2 Oxoanions have been classified as toxic priority pollutants under the Clean Water Act, and because tolerable concentrations are often exceeded, targeted treatment of affected bodies of water becomes necessary. 3,4 Several treatment mechanisms have been developed to remediate water sources from these pollutants ranging from the facilitation of degradation processes and use of activated carbon capture to the deployment of sorbents (such as metal−organic and covalent−organic frameworks) for explicit removal of oxoanions. 5−13 The latter approach is the focus of this investigation, for which high capacity, porous materials including metal−organic frameworks (MOFs) have found efficient implementation as sorbents.…”