Collect. Czech. Chem. Commun. 2010, 75, 405-424
doi:10.1135/cccc2009535
Published online 2010-04-15 09:29:41

Solvation and ion pair association in aqueous metal sulfates: Interpretation of NDIS raw data by isobaric–isothermal molecular dynamics simulation

Ariel A. Chialvoa,* and J. Michael Simonsonb

a Chemical Sciences Division, Geochemistry and Interfacial Science Group, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6110, USA
b Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6496, USA

Abstract

We analyzed the solvation behavior of aqueous lithium, nickel, and ytterbium sulfates at ambient conditions in terms of the relevant radial distributions functions and the corresponding first-order difference of the sulfur-site neutron-weighted distribution functions generated by isothermal-isobaric molecular dynamics simulation. We determined the partial contributions to the neutron-weighted distribution functions, to identify the main contributing peaks of the corresponding radial distribution functions, and the effect of the contact ion-pair configuration on the resulting water’s hydrogen coordination around the sulfate’s sulfur site. Finally, we assessed the extent of the ion-pair formation according to Poirier–DeLap formalism and highlighted the significant increase of the ion-pair association exhibited by these salts with cation charge.

Keywords: Neutron diffraction; Molecular dynamics; Ion pairs; Anion hydration; NDIS; Coordination number; Radial distribution functions.

References: 32 live references.