Structure and Dynamics of Ions and Fluids at Organo-Mineral-Fluid Interfaces
EMSL Project ID
48271
Abstract
Our research program strives to provide new insight into the fundamental molecular-scale dynamics, energetics, and reactivity of geochemically relevant solid-fluid interfaces through combined spectroscopy and molecular modeling. This science theme proposal furthers our mission by using the unique capabilities of several EMSL resources to study how natural organic polymers (e.g. natural organic matter [NOM]) affect the interfacial behavior of H2O, CO2, and ions at phyllosilicate-H2O, phyllosilicate-supercritical CO2 (scCO2), and phyllosilicate-H2O-scCO2 interfaces. The behavior of fluids, organic matter, and metal ions at such interfaces has direct and important implications on nutrient cycling, carbon dioxide sequestration, the fate and transport of metal and organic contaminants, surface chemistry and biochemistry in soils and natural waters, heterogeneous catalysis, and long-term sequestration of nuclear waste. Specific objectives of the proposed research are to (i) characterize the binding sites, dynamic averaging mechanisms, rates of molecular motion on the 10-5 to 10-10 s time scales, and the chemical controls over these processes for alkali and alkaline earth metals in smectite-NOM composite materials; (ii) characterize the binding sites and dynamics of cations in hydrated NOM aggregates; and (iii) examine the molecular-scale binding and dynamics of CO2, H2O, and ions in smectite-NOM composites with varying degrees of hydration under in situ supercritical CO2 conditions. The high-field NMR instrumentation and specialized high-pressure NMR rotor system at EMSL are essential to overcome sensitivity limitations associated with the low-gamma quadrupolar nuclei involved in these studies (39K, 43Ca, 25Mg, 87Sr), to the novel in situ scCO2 experiments, and to provide necessary data for comparison with molecular dynamics computer simulations performed by our group off site. Characterizing the spatial arrangement of the clay layers and pore structure of these materials will also be crucial, and can be achieved using SEM/HeIM methods in the EMSL charged beam microscopy facilities and the microXRD instrument at EMSL. This work will contribute directly toward several papers combining spectroscopic and computational results over the life of the proposal and serve as the basis for several undergraduate theses and the professional development of at least one post-doc.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2014-10-01
End Date
2015-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Bowers GM, HE Argersinger, V Reddy, TA Johnson, BW Arey, ME Bowden, and RJ Kirkpatrick. 2015. "Integrated Molecular and Microscopic Scale Insight into Morphology and Ion Dynamics in Ca2+-Mediated Natural Organic Matter Floccs." Journal of Physical Chemistry C 119(31):17773-17783. doi:10. 1021/acs. jpcc. 5b05509
Kirkpatrick R J,Kalinichev A G,Bowers G M,Yazaydin A O,Krishnan M ,Saharay M ,Morrow C P 2015. "NMR and Computational Molecular Modeling Studies of Mineral Surfaces and Interlayer Galleries: A Review" The American Mineralogist 100(7):1341-1354. 10.2138/am-2015-5141