Structural and quantitative analysis of water association in ethylammonium nitrate mixtures using soft modeling resolution of NIR spectra and molecular dynamics simulations

Identifier:  imarina:9138892

Handle: https://hdl.handle.net/20.500.11797/imarina9138892

Authors:  Rodríguez-Barrios, MS; Rodríguez-Fortea, A; Varela, LM; Salavera, D; Larrechi, MS; Coronas, A

Abstract:
© 2020 Elsevier B.V. In this work we report on the structural and quantitative analysis of the water association in ethylammonium nitrate mixtures (EAN + H2O) using multivariate curve resolution based on alternate least squares (MCR-ALS) of Near Infrared (NIR) spectra and Car-Parrinello Molecular Dynamics (MD) simulations. MCR-ALS methodology was used to determine the concentration of the chemical species in the EAN + H2O mixtures, as well as the molar ratio between the coordinated EAN-H2O species. Measurements were performed over the entire range of IL mass fraction at three temperatures 298.15 K, 308.15 K and 318.15 K. The experimental results revealed the existence of three chemical environments, bulk water (H2O), neat ionic liquid (EAN), and solvated ionic liquid (EAN-H2O) in the mixtures. The hydration process of EAN was observed to be favorable for EAN mole fractions lower than 0.138. Car-Parrinello MD simulations were used to perform the structural analysis of selected mixtures. Simulations showed an increase of the water/EAN molar ratio in EAN-water complexes when the percentage of water in the mixtures was increased. In addition, they confirmed the reliability of previous classical MD simulations to analyze the interactions in the hydrogen-bonded network that is solvating EAN anions and cations.