Structural investigations of high concentrated aqueous LiCl solutions: X-ray scattering and MD simulations approach

A detailed analysis of aqueous LiCl solution structures is performed by molecular dynamics (MD) simulations and X-ray scattering at two salt concentrations (6 and 7 m) at 298 K. Another run is performed for C = 14 m. MD simulations are carried out with rigid SPC water model, while the ions are treated as charged Lennard-Jones particles. Both MD and X-ray scattering investigations show a significant reorganization of the solvent. The degree of hydrogen bonding of which clearly decreases when compared to pure fluid. MD results also show that the first hydration shell of the cation is greatly distorted at high concentrations whereas the corresponding one of the anion appears nearly invariant. Moreover, the ion-pairing process is accented at highest salt concentration. X-ray data are analyzed to deduce the structure factor and the pair correlation functions of each system. A good concordance is highlighted between experimental and theoretical results. A model of intermolecular arrangement, via MD results, is then proposed to describe the local order in each system, as deduced from X-ray scattering data.