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N. Dawass

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9 records found

Kirkwood–Buff integrals of finite systems

Shape effects

Journal article - N. Dawass, P. Krüger, JM Simon, T.J.H. Vlugt

The Kirkwood–Buff (KB) theory provides an important connection between microscopic density fluctuations in liquids and macroscopic properties. Recently, Krüger et al. derived equations for KB integrals for finite subvolumes embedded in a reservoir. Using molecular simulation of f ...

Kirkwood–buff integrals using molecular simulation

Estimation of surface effects

Journal article - N. Dawass, P. Krüger, Sondre K. Schnell, O. Moultos, Ioannis G. Economou, Ioannis G. Economou, T.J.H. Vlugt, JM Simon, JM Simon

Kirkwood–Buff (KB) integrals provide a connection between microscopic properties and thermodynamic properties of multicomponent fluids. The estimation of KB integrals using molecular simulations of finite systems requires accounting for finite size effects. In the small system me ...

Brick-CFCMC

Open Source Software for Monte Carlo Simulations of Phase and Reaction Equilibria Using the Continuous Fractional Component Method

Journal article - R. Hens, A. Rahbari, D. Dubbeldam, T.J.H. Vlugt, S.A. Caro Ortiz, N. Dawass, M. Erdös, A. Poursaeidesfahani, H. Seyed Salehi, A.T. Celebi, M. Ramdin, O. Moultos

We present a new molecular simulation code, Brick-CFCMC, for performing Monte Carlo simulations using state-of-the-art simulation techniques. The Continuous Fractional Component (CFC) method is implemented for simulations in the NVT/NPT ensembles, the Gibbs Ensemble, the Grand-Ca ...

How sensitive are physical properties of choline chloride-urea mixtures to composition changes

Molecular dynamics simulations and Kirkwood-Buff theory

Journal article - A.T. Celebi, N. Dawass, O. Moultos, T.J.H. Vlugt

Deep eutectic solvents (DESs) have emerged as a cheaper and greener alternative to conventional organic solvents. Choline chloride (ChCl) mixed with urea at a molar ratio of 1:2 is one of the most common DESs for a wide range of applications such as electrochemistry, material sci ...

Kirkwood–buff integrals from molecular simulation

Doctoral thesis - N. Dawass

The Kirkwood–Buff (KB) theory is one of the most rigorous solution theories that connects molecular structure to macroscopic behaviour. The key quantity, the so–called KB Kirkwood–Buff Integrals (KBIs), are defined either in terms of fluctuations in the number of molecules or int ...

Finite-size effects of Kirkwood–Buff integrals from molecular simulations

Journal article - N. Dawass, P. Krüger, P. Krüger, S. K. Schnell, D. Bedeaux, S Kjelstrup, J. M. Simon, T.J.H. Vlugt

The modelling of thermodynamic properties of liquids from local density fluctuations is relevant to many chemical and biological processes. The Kirkwood–Buff (KB) theory connects the microscopic structure of isotropic liquids with macroscopic properties such as partial derivative ...

Kirkwood-Buff integrals from molecular simulation

Journal article - N. Dawass, P. Krüger, S. K. Schnell, Jean Marc Simon, T.J.H. Vlugt

The Kirkwood-Buff (KB) theory provides a rigorous framework to predict thermodynamic properties of isotropic liquids from the microscopic structure. Several thermodynamic quantities relate to KB integrals, such as partial molar volumes. KB integrals are expressed as integrals of ...

Solubility of Carbon Dioxide, Hydrogen Sulfide, Methane, and Nitrogen in Monoethylene Glycol; Experiments and Molecular Simulation

Journal article - N. Dawass, Ricardo R. Wanderley, M. Ramdin, O. Moultos, Hanna K. Knuutila, T.J.H. Vlugt

Knowledge on the solubility of gases, especially carbon dioxide (CO2), in monoethylene glycol (MEG) is relevant for a number of industrial applications such as separation processes and gas hydrate prevention. In this study, the solubility of CO2 in MEG was measured experimentally ...

Solubilities and Transport Properties of CO<sub>2</sub>, Oxalic Acid, and Formic Acid in Mixed Solvents Composed of Deep Eutectic Solvents, Methanol, and Propylene Carbonate

Journal article - N. Dawass, Jilles Langeveld, M. Ramdin, Elena Pérez-Gallent, Angel A. Villanueva, Erwin J.M. Giling, Jort Langerak, L.J.P. van den Broeke, T.J.H. Vlugt, O. Moultos

Recently, deep eutectic solvents (DES) have been considered as possible electrolytes for the electrochemical reduction of CO2 to value-added products such as formic and oxalic acids. The applicability of pure DES as electrolytes is hindered by high viscosities. Mixtures of DES with organic solvents can be a promising way of designing superior electrolytes by exploiting the advantages of each solvent type. In this study, densities, viscosities, diffusivities, and ionic conductivities of mixed solvents comprising DES (i.e., reline and ethaline), methanol, and propylene carbonate were computed using molecular simulations. To provide a quantitative assessment of the affinity and mass transport of CO2 and oxalic and formic acids in the mixed solvents, the solubilities and self-diffusivities of these solutes were also computed. Our results show that the addition of DES to the organic solvents enhances the solubilities of oxalic and formic acids, while the solubility of CO2 in the ethaline-containing mixtures are in the same order of magnitude with the respective pure organic components. A monotonic increase in the densities and viscosities of the mixed solvents is observed as the mole fraction of DES in the mixture increases, with the exception of the density of ethaline-propylene carbonate which shows the opposite behavior due to the high viscosity of the pure organic component. The self-diffusivities of all species in the mixtures significantly decrease as the mole fraction of DES approaches unity. Similarly, the self-diffusivities of the dissolved CO2 and the oxalic and formic acids also decrease by at least 1 order of magnitude as the composition of the mixture shifts from the pure organic component to pure DES. The computed ionic conductivities of all mixed solvents show a maximum value for mole fractions of DES in the range from 0.2 to 0.6 and decrease as more DES is added to the mixtures. Since for most mixtures studied here no prior experimental measurements exist, our findings can serve as a first data set based on which further investigation of DES-containing electrolyte solutions can be performed for the electrochemical reduction of CO2 to useful chemicals. @en

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Thermodynamic, Transport and Structural Properties of Deep Eutectic Solvent Mixtures Relevant to Capture and Conversion of CO2 to Value Added Products

A Molecular Dynamics Study

Master thesis - J. Langeveld, O. Moultos, N. Dawass, P. Dey, T.J.H. Vlugt

The current industrial application of carbon capture utilization and storage (CCUS) is limited due to technological drawbacks such as high energy demand and environmental pollution. Ionic liquids (ILs) and deep eutectic solvents (DESs) are considered promising alternative solvents for the capture of carbon dioxide (CO2). DESs are often characterized by high viscosities, which hinders industrial application. This problem might be solved by mixing the DES with an organic solvent. This study aims to assess the DESs choline chloride-ethylene glycol (ethaline) and choline chloride-urea (reline) mixed with methanol and propylene carbonate (PC) for their suitability as a medium for the combined capture and electrochemical conversion of CO2. Molecular dynamics (MD) simulations are performed to obtain the densities, the viscosities, the self-diffusivities, the ionic conductivities and insight into the molecular interactions of these mixtures. Independent MD simulations are performed of these mixtures with low concentrations of the solutes CO2, oxalic acid and formic acid. Complementary studies within the Bio-cel project are conducted to characterize the solubility and electrochemical reaction of CO2 and the techno-economics. The viscosities of the mixtures monotonically decrease for an increase of mole fraction of organic solvent, which is benign for the application of CCUS. The self-diffusivities of all constituents increase monotonically for an increase of mole fraction of organic solvent. The ionic conductivity is calculated based on the ion self-diffusivities. Ionic conductivity optima are found at a mole fraction of DES of approximately 0.6 for ethaline-PC and approximately 0.2 for ethaline-methanol and reline-methanol. For higher mole fractions of organic solvent, the ionic conductivity decreases due to a depletion of ions. Radial distribution functions (RDFs) are used to analyse the intermolecular interactions. RDF peaks between chloride-choline and chloride-ethylene glycol show an increase for an increasing mole fraction of organic solvent, which was unexpected. The numbers of hydrogen bonds decrease for addition of methanol to pure deep eutectic solvent. For addition of propylene carbonate, this decrease is less pronounced. The depletion of hydrogen bonds at low mole fractions of deep eutectic solvent is in correspondence with the decrease in viscosity and increase in self-diffusivities. The results indicate that, for the studied properties, deep eutectic solvents mixed with organic solvents are more favourable than pure deep eutectic solvents for the absorption and electrochemical conversion of CO2.