Mechanisms of Dissolution from Gibbsite Step Edges Elucidated by Ab Initio Molecular Dynamics with Enhanced Sampling

20 June 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Many predictive models of geochemical processes (e.g., fate and transport of metals) and industrial utilization of minerals rely upon a detailed understanding of mineral dissolution. Yet atomistic details are rarely known due to the complex mineral/fluid interfacial environment. Here, ab initio molecular dynamics simulations with enhanced sampling has been used to explore the detailed process of the detachment of an aluminate monomer from two types of step edges at the gibbsite aqueous interface. Gibbsite is a primary source of Al in soils and mineral within the industrial processing of aluminum. Surface pit models in conjunction with changes to solution composition that mimic pH effects are employed to create realistic starting points for the simulation. The results indicate two potential pathways for detachment that are differentiated based upon the extent of water hydration. The energy profiles of the elementary bond-breaking events indicate the scission of the first or the second hydroxo bridge is the rate-limiting step for the monomer dissociation. The heights of the energy barriers depend upon the local morphology which influence the number of bridges (quasi-)simultaneously broken (1 or 2) or the Al-O coordination of the neighboring aluminum atoms (5 or 6) at the armchair edge.


mineral dissolution

Supplementary materials

Supplementary Information
The supplementary material contains: (1) Hydrogen bonding of the desorbing water: radial distribution functions;382 (2) Distribution of the number of Al-OH-Al bridges in different CN(Al-Al) umbrella sampling windows; (3) Structures383 of the first transition state for the armchair edge; (4) Boxplots of the Al-𝜇2O bond distributions; (5) Research data for384 the plots in this article.


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.