A5014867769- Calcium Carbonate Crystallization and Inhibition
- Iron oxide chemistry and applications
- Clay minerals and soil interactions
- Radioactive element chemistry and processing
- Seismic Waves and Analysis
- High-pressure geophysics and materials
- Chemical and Physical Properties in Aqueous Solutions
- Earthquake Detection and Analysis
- Nuclear materials and radiation effects
- Geochemistry and Elemental Analysis
- Spectroscopy and Quantum Chemical Studies
- X-ray Diffraction in Crystallography
- Crystal Structures and Properties
- CO2 Sequestration and Geologic Interactions
- Geological and Geochemical Analysis
- Minerals Flotation and Separation Techniques
- Crystallization and Solubility Studies
- Perovskite Materials and Applications
- Thermal and Kinetic Analysis
- Mine drainage and remediation techniques
- Radioactive contamination and transfer
- Building materials and conservation
- Cephalopods and Marine Biology
- Material Dynamics and Properties
- Concrete and Cement Materials Research
Pacific Northwest National Laboratory
2019-2025
Battelle
2023
Virginia Tech
2016-2021
Richland College
2020
Physical Sciences (United States)
2020
We establish the connection between measured small angle x-ray scattering signal and charge–charge correlations underlying Kirkwood transitions (KTs) in 1:1, 2:1, 3:1 aqueous electrolytes. These measurements allow us to obtain underscreening lengths for bulk electrolytes independently verified by theory simulations. Furthermore, we generalize concept of KTs beyond those theoretically predicted 1:1 electrolytes, which involves inverse screening length, a0, periodicity Q0. Above KTs, find a...
Two-dimensional (2D) materials have attracted intense interest due to their potential for applications in fields ranging from chemical sensing catalysis, energy storage, and biomedicine. Recently, peptoids, a class of biomimetic sequence-defined polymers, been found self-assemble into 2D crystalline sheets that exhibit unusual properties, such as high stability the ability self-repair. The structure peptoid is close peptide except side chains are appended amide nitrogen rather than α carbon....
Injecting supercritical CO2 (scCO2) into basalt formations for long-term storage is a promising strategy mitigating emissions. Mineral carbonation can result in permanent entrapment of CO2; however, kinetics thin H2O films humidified scCO2 not well understood. We investigated forsterite (Mg2SiO4) to magnesite (MgCO3) via amorphous magnesium carbonate (AMC; MgCO3·xH2O, 0.5 < x 1), with the goal establish fundamental controls on growth rates at low activity and temperature. Experiments were...
Amorphous calcium phosphate (ACP) is a metastable phase in the crystallization pathway of phosphates. Understanding its chemical and structural properties could provide critical insights into biomineralization mechanisms. Of particular interest impact initial Ca/P on structure ACP. Further, influence size, precipitate chemistry, transformation ACP crucial to understanding metastability amorphous In situ pair distribution function (PDF) analysis results 5 min after mixing show that Ca–P...
The preparation of metastable zeolites is often restricted to a limited range synthesis conditions, which exemplified in commercial syntheses lacking organics stabilize the crystal structure. In absence an organic structure-directing agent, interzeolite transformation common phenomenon that can lead undesirable products or impurities. Many studies have investigated substitution Si and Al zeolite frameworks with alternative elements (heteroatoms) as means tailoring properties zeolites;...
Iodide elpasolites (or double perovskites, A2B′B″I6, B′ = M+, B″ M3+) are predicted to be promising alternatives lead-based perovskite semiconductors for photovoltaic and optoelectronic applications, but no iodide elpasolite has ever been definitively prepared or structurally characterized. widely unstable due favorable decomposition the competing A3B2I9 (B phase. Here, we report results of synchrotron X-ray diffraction (XRD) total scattering measurements on putative Cs2AgBiI6 nanocrystals...
Zn is an essential micronutrient that often limited in tropical, lateritic soils part because it sequestered nominally refractory iron oxide phases. Stable phases such as goethite and hematite, however, can undergo reductive recrystallization without a phase change under circumneutral pH conditions release metal impurities into aqueous solutions. Further, the process appears to be driven by Fe vacancies. In this contribution, we used ab initio molecular dynamics informed extended X-ray...
Meeting global sustainable development and climate goals requires a rapid transition to renewable energy technologies. However, these emerging technologies rely on critical elements whose sourcing presents geopolitical environmental challenges....
Using ab initio based molecular dynamics and electronic structure calculations, we show that Zn impurities in hydrated amorphous calcium carbonate (ACC) have a much lower coordination number than other divalent due to covalent interactions between the 3d shell oxygen atoms of water groups. The local around ACC, including predicted low number, is confirmed by X-ray absorption spectroscopy synthetic Zn-bearing ACC. strong Zn–O chemical interaction leads substantial dissociation slightly...
A synthesis method for nanosized forsterite (Mg 2 SiO 4 ) doped with varying concentrations of Ni and Co has been developed to support studies carbonation-based extraction separation from mafic ultramafic rocks.
Iron oxide minerals regulate the flux of electrons in environment and are important hosts for trace minor, yet critical, elements. Here, we present first evidence a direct link between local coordination environments Ni Zn redox properties their host phase goethite (α-FeOOH), most abundant Fe(III) (oxyhydr)oxide at Earth's surface. We used aqueous measurements to show that potential EH0, hence mineral's stability, follows order: pure ≥ Zn-goethite > Ni-goethite. Parallel X-ray absorption...
Successful deployment of in situ subsurface remediation strategies requires knowledge contaminant geochemistry, and the impact physicochemical sediment properties on remedy performance. Bismuth (Bi) materials can sequester multiple contaminants...
A fundamental understanding of processes that slow divalent metal silicate carbonation is important for developing effective strategies to durably store carbon dioxide and mitigate atmospheric CO2. This study presents a detailed investigation passivation effect unique low-water conditions during the forsterite (Mg2SiO4) highlights importance hygroscopicity in influencing carbonation. Integrated situ ex experimental results showed decrease rate observed after ∼10 h humid supercritical CO2 (50...
Technetium-99 immobilization in low-temperature nuclear waste forms often relies on additives that reduce environmentally mobile pertechnetate (TcO4–) to insoluble Tc(IV) species. However, this is a short-lived solution unless reducing conditions are maintained over the hazardous life cycle of radioactive wastes (some ∼10,000 years). Considering recent experimental observations, work explores how rapid formation ettringite [Ca6Al2(SO4)3(OH)12·26(H2O)], common mineral formed cementitious...
Forsterite carbonated in thin H2O films to magnesite via amorphous magnesium carbonate during reaction with H2O-bearing liquid CO2 at 25 °C. This novel pathway contrasts previous studies that were carried out higher activity and temperature, where more highly hydrated nesquehonite was the metastable intermediate.
Characterizing the chemical state and physical disposition of uranium that has persisted over geologic time scales is key for modeling long-term sequestration nuclear waste, accurate uranium–lead dating, use isotopes as paleo redox proxies. X-ray absorption spectroscopy coupled with molecular dynamics demonstrated pentavalent incorporated in structure 1.6 billion year old hematite (α-Fe2O3), attesting to robustness Fe oxides waste forms revealing reason great success using petrogenic dating....
Passivation of silicate surfaces by accumulated reaction products is an obstacle to efficient CO2 mineralization. In this study, we investigate a unique passivation effect during the carbonation basalt mineral forsterite (Mg2SiO4) in humid supercritical (50 °C, 90 bar). Using situ high-pressure infrared spectroscopy, demonstrate that dissolution into thin water film slows significantly after for ≈24 h, even under far-from-equilibrium conditions. 29Si magic angle spinning nuclear magnetic...
Nanoparticle aggregates in solution controls surface reactivity and function. Complete dispersion often requires additive sorbents to impart a net repulsive interaction between particles. Facet engineering of nanocrystals offers an alternative approach produce monodisperse suspensions simply based on facet-specific with solvent molecules. Here, we measure the dispersion/aggregation three morphologies hematite (α-Fe
Temperature modulation was demonstrated as a novel way to control water partitioning during the reaction of silicate minerals with water-saturated supercritical carbon dioxide.