Is Stokes-Einstein relation valid for the description of intra-diffusivity of hydrogen and oxygen in liquid water?

Is Stokes-Einstein relation valid for the description of intra-diffusivity of hydrogen and oxygen in liquid water?

Tsimpanogiannis, Ioannis N. (Centre for Research and Technology)
Moultos, O. (TU Delft Engineering Thermodynamics)

2022

In this study, all available data from experiments and molecular simulations for the intra-diffusivities of H₂ and O₂ in H₂O, and for the self-diffusivity of pure H₂O are analyzed to examine the validity of the Stokes-Einstein relation. This analysis is motivated by the significant amount of work devoted through the years for improving the predictions of intra- and self-diffusivities in binary and multi-component mixtures relevant to chemical and environmental processes. Here, we calculate the slopes s and t corresponding to the ln(D)vs.ln[Formula presented] plots, respectively, where D is the intra-diffusivity, η the viscosity, and T the temperature of the systems. Our results show that s and t deviate from unity no matter if the experimental or simulation data are used. This means that the Stokes-Einstein relation is violated for the binary systems of H₂ and O₂ with H₂O, and for pure H₂O. Although prior studies mainly focused on re-evaluating the parameter A of the SE-based semi-theoretical/semi-empirical approaches expressed as [Formula presented], our results indicate that reliable predictions for the intra- and self-diffusivities can be achieved by improving the accuracy of the prediction of slopes s and t.

Diffusion
Hydrogen
Molecular dynamics
Oxygen
Stokes-Einstein
Water

http://resolver.tudelft.nl/uuid:239cb48b-6ec9-43f7-8a0d-2d3b343226e1

https://doi.org/10.1016/j.fluid.2022.113568

0378-3812

Fluid Phase Equilibria, 563

Institutional Repository

journal article

© 2022 Ioannis N. Tsimpanogiannis, O. Moultos