Issue 2, 2019, Issue in Progress

Anionic effects on the structure and dynamics of water in superconcentrated aqueous electrolytes

Abstract

Dissolved ions in aqueous solutions are ubiquitous in a variety of systems and the addition of ions to water gives rise to dramatic effects on the properties of water. Due to a significant role of ions in the structure and dynamics of water, the ionic conditions, such as the ion type and concentration, have been considered as critical factors. Here we study the effects of anions on the structure and dynamics of water in aqueous electrolytes for various lithium salt concentrations via extensive molecular dynamics simulations. Our results demonstrate that a certain amount of salt is needed to show the different properties of water caused by the presence of different types of anion. Below the cutoff concentration, most features of water show the same characteristics in spite of the presence of different anions. In the superconcentrated limit, we find that full disruption of the hydrogen bond network between water molecules occurs for most anions investigated, indicating that the effect of the water–water interaction becomes negligible. However, a certain type of anion could enhance an ion-pairing of cations and anions and the water–water interaction remains considerable even in the superconcentrated limit. We further investigate the cationic and anionic hydration shell structures and dynamics, revealing their dependence on the anion type and the salt concentration. Finally, we observe that the anionic effects on water extend to the dynamics of water molecules, such as an anionic dependence of the onset of subdiffusive translation and anisotropic rotation.

Graphical abstract: Anionic effects on the structure and dynamics of water in superconcentrated aqueous electrolytes

Article information

Article type
Paper
Submitted
21 Nov 2018
Accepted
09 Dec 2018
First published
02 Jan 2019
This article is Open Access
Creative Commons BY license

RSC Adv., 2019,9, 609-619

Anionic effects on the structure and dynamics of water in superconcentrated aqueous electrolytes

S. Han, RSC Adv., 2019, 9, 609 DOI: 10.1039/C8RA09589B

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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