Local structure of NH4Cl solution and its correlation with osmotic coefficient by molecular dynamics simulation and Raman spectroscopy

Abstract

The NH4Cl aqueous solution ranging from 1.00 wt.% to 22.00 wt.% have been studied by molecular dynamic simulation, Raman spectroscopy and polarized Raman spectroscopy. Radial distribution function (RDF), diffusion property, structure of hydrogen bond network, excess Raman spectroscopy and non-coincidence effect (NCE) were obtained. The contact ion pairs of cation and anion appeared in NH4Cl solution of 15.00 wt.%, leading to fundamental changes in hydrogen bonds and the hydrated shell. The evolution of hydrogen bond with mass fraction in solution was described. The osmotic coefficient of NH4Cl aqueous solution was obtained by thermodynamic calculation, and its linear relationship with double donor single acceptor hydrogen bond (DDA-OH) was preliminarily summarized. Moreover, the experimental results are in good agreement with the simulation results.