Lead and selenite adsorption at water–goethite interfaces from first principles

Journal Article · Fri Aug 04 00:00:00 EDT 2017 · Journal of Physics. Condensed Matter

DOI:https://doi.org/10.1088/1361-648x/aa7e4f· OSTI ID:1406368

Leung, Kevin ^[1]; Criscenti, Louise J. ^[1]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Here, the complexation of toxic and/or radioactive ions on to mineral surfaces is an important topic in geochemistry. We apply periodic-boundary-conditions density functional theory (DFT) molecular dynamics simulations to examine the coordination of Pb(II), $${\rm SeO}_3^{2-}$$ , and their contact ion pairs to goethite (1 0 1) and (2 1 0) surfaces. The multitude of Pb(II) adsorption sites and possibility of Pb(II)-induced FeOH deprotonation make this a complex problem. At surface sites where Pb(II) is coordinated to three FeO and/or FeOH groups, and with judicious choices of FeOH surface group protonation states, the predicted Fe–Pb distances are in good agreement with EXAFS measurements. Trajectories where Pb(II) is in part coordinated to only two surface Fe–O groups exhibit larger fluctuations in Pb–O distances. Pb(II)/$${\rm SeO}_3^{2-}$$ contact ion pairs are at least metastable on goethite (2 1 0) surfaces if the $${\rm SeO}_3^{2-}$$ has a monodentate Se–O–Fe bond. Our DFT-based molecular dynamics calculations are a prerequisite for calculations of finite temperature equilibrium binding constants of Pb(II) and Pb(II)/$${\rm SeO}_3^{2-}$$ ion pairs to goethite adsorption sites.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1406368
• Report Number(s): SAND--2017-11359J; 657957
• Journal Information: Journal of Physics. Condensed Matter, Journal Name: Journal of Physics. Condensed Matter Journal Issue: 36 Vol. 29; ISSN 0953-8984
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
density functional theory molecular dynamics
deprotonation
ion adsorption
water-material interface