Molecular Simulations of Biofuel and Water Purification in Metal-Organic Frameworks

Ph.DDOCTOR OF PHILOSOPH

Application of metal − organic frameworks

The burgeoning field of metal-organic frameworks or porous coordination polymers has received increasing interest in recent years. In the last decade these microporous materials have found several applications including storage and separation of gases, sensors, catalysis and functional materials. In order to better design new metal-organic frameworks and porous coordination polymers with specific functionalities a fundamental issue is to achieve a basic understanding of the relationship between molecular parameters and structures, preferred adsorption sites and properties by using using modern theoretical methods. The focus of this mini-review is a description of the potential and emerging applications of metal-organic framework

Enhanced sampling in molecular dynamics using metadynamics, replica-exchange, and temperature-acceleration

We review a selection of methods for performing enhanced sampling in molecular dynamics simulations. We consider methods based on collective variable biasing and on tempering, and offer both historical and contemporary perspectives. In collective-variable biasing, we first discuss methods stemming from thermodynamic integration that use mean force biasing, including the adaptive biasing force algorithm and temperature acceleration. We then turn to methods that use bias potentials, including umbrella sampling and metadynamics. We next consider parallel tempering and replica-exchange methods. We conclude with a brief presentation of some combination methods. \ua9 2013 by the author; licensee MDPI, Basel, Switzerland

Stability and Hydrolyzation of Metal Organic Frameworks with Paddle-Wheel SBUs upon Hydration

Instability of most prototypical metal organic frameworks (MOFs) in the presence of moisture is always a limita- tion for industrial scale development. In this work, we examine the dissociation mechanism of microporous paddle wheel frameworks M(bdc)(ted)0.5 [M=Cu, Zn, Ni, Co; bdc= 1,4-benzenedicarboxylate; ted= triethylenediamine] in controlled humidity environments. Combined in-situ IR spectroscopy, Raman, and Powder x-ray diffraction measurements show that the stability and modification of isostructual M(bdc)(ted)0.5 compounds upon exposure to water vapor critically depend on the central metal ion. A hydrolysis reaction of water molecules with Cu-O-C is observed in the case of Cu(bdc)(ted)0.5. Displacement reactions of ted linkers by water molecules are identified with Zn(bdc)(ted)0.5 and Co(bdc)(ted)0.5. In contrast,. Ni(bdc)(ted)0.5 is less suscept- ible to reaction with water vapors than the other three compounds. In addition, the condensation of water vapors into the framework is necessary to initiate the dissociation reaction. These findings, supported by supported by first principles theoretical van der Waals density functional (vdW-DF) calculations of overall reaction enthalpies, provide the necessary information for de- termining operation conditions of this class of MOFs with paddle wheel secondary building units and guidance for developing more robust units

Metal?Organic Frameworks for Liquid Phase Applications

10.1002/advs.202003143Advanced Science85200314

Recovery of dimethyl sulfoxide from aqueous solutions by highly selective adsorption in hydrophobic metal-organic frameworks

10.1021/la3034116Langmuir284315305-15312LANG

Water Permeation through Conical Nanopores: Complex Interplay between Surface Roughness and Chemistry

10.1002/adts.202000025Advanced Theory and Simulations35200002

Biofuel purification by pervaporation and vapor permeation in metal-organic frameworks: A computational study

10.1039/c0ee00630kEnergy and Environmental Science462107-211

Enhancing water permeation through alumina membranes by changing from cylindrical to conical nanopores

10.1039/c8nr09602cNanoscale11209869-987

Ion Exchange in Metal–Organic Framework for Water Purification: Insight from Molecular Simulation

A molecular simulation study is reported for ion exchange in a <i>rho</i> zeolite-like metal–organic framework (ZMOF). The nonframework Na⁺ ions in <i>rho</i>-ZMOF are observed to exchange with Pb²⁺ ions in PbCl₂ solution. At equilibrium, all Pb²⁺ ions are exchanged and reside in <i>rho</i>-ZMOF, while Na⁺ ions are in a dynamic equilibrium with solution. By umbrella sampling, the potential of mean force for Pb²⁺ moving from solution into <i>rho</i>-ZMOF is estimated to be −10<i>k</i>_B<i>T</i>, which is more favorable than −5<i>k</i>_B<i>T</i> for Na⁺ and contributes to the observed ion exchange. The residence-time distributions and mean-squared displacements reveal that all the exchanged Pb²⁺ ions stay continuously in <i>rho</i>-ZMOF without exchanging with other ions in solution due to strong interaction with <i>rho</i>-ZMOF; however, Na⁺ ions have a shorter residence time and a larger mobility than Pb²⁺ ions. The exchanged Pb²⁺ ions in <i>rho</i>-ZMOF are located at eight-, six-, and four-membered rings. As attributed to the confinement effect, distinctly different dynamic properties are found for Pb²⁺ ions at the three locations. Pb²⁺ ions at 8MR have the highest mobility due to the largest ring size, while those at 4MR have a negligible mobility. This simulation study provides microscopic insight into the ion-exchange process in ionic MOF and suggests that <i>rho</i>-ZMOF might be an intriguing candidate for water purification