A5080231841- Iron oxide chemistry and applications
- Mine drainage and remediation techniques
- Arsenic contamination and mitigation
- Metal Extraction and Bioleaching
- Chromium effects and bioremediation
- Catalytic Processes in Materials Science
- Minerals Flotation and Separation Techniques
- Geochemistry and Geologic Mapping
- Adsorption and biosorption for pollutant removal
- Geochemistry and Elemental Analysis
- Clay minerals and soil interactions
- Radioactive element chemistry and processing
- Geological and Geochemical Analysis
- Peatlands and Wetlands Ecology
- Environmental remediation with nanomaterials
- Therapeutic Uses of Natural Elements
- Nanocluster Synthesis and Applications
- Coal and Its By-products
- Extraction and Separation Processes
- Geoscience and Mining Technology
- Analytical chemistry methods development
- Healthcare and Environmental Waste Management
- Fire effects on ecosystems
Virginia Tech
2018-2024
Stanford University
2023-2024
Georgia State University
2019
University of Tehran
2015-2018
The presence of oxyanions, such as nitrate (NO3–) and phosphate (PO43–), regulates the nucleation growth goethite (Gt) hematite (Hm) during transformation ferrihydrite (Fh). Our previous studies showed that oxyanion surface complexes control rate pathway Fh to Gt Hm. However, how mechanism Hm is still unclear. We used synchrotron scattering methods cryogenic transmission electron microscopy investigate effects NO3– outer-sphere PO43– inner-sphere on formation from Fh. TEM results indicated...
The rate and pathway of ferrihydrite (Fh) transformation at oxic conditions to more stable products is controlled largely by temperature, pH, the presence other ions in system such as nitrate (NO3–), sulfate (SO42–), arsenate (AsO43–). Although mechanism Fh oxyanion complexation have been separately studied, effect surface complex type strength on remains only partly understood. We developed a kinetic model that describes effects goethite (Gt) hematite (Hm). Two sets oxyanion-adsorbed...
Rapid precipitation of iron oxy-hydroxide clusters at pH > 4.5 during hydrolysis can lead to the formation metastable ferrihydrite while their aging acidic (<2.5) forms stable products such as goethite and lepidocrocite.
In natural environments, ferrihydrite (Fh) reacts readily with the contaminant and nutrient oxyanions through surface complexation. While previous experiments showed that transformation of Fh to Gt Hm under oxic conditions at 70 °C is controlled by type strength oxyanion complexes, impact loading on this process only partly understood. Synchrotron scattering methods chemical analysis were used develop a kinetic model describes rate pathway using arsenate (AsO43–) phosphate (PO43–). Kinetic...
Oxidation of chromium (Cr)-bearing minerals by manganese (Mn) oxides is viewed as the dominant mechanism controlling geogenic production Cr(VI) and its contamination groundwater. This process may be modulated other chemical constituents found in natural environment, but such confounding factors have not been quantified. Here, we evaluated Cr(III) oxidation mixed-valence Mn oxide presence citric gallic acids, two organic matter (NOM) commonly soil environment. Incubation experiments showed...
Wildfires are increasing in frequency and severity, as evident the western U.S., can impact formation, transformation, dispersion of toxic nanoparticles smoke, post-fire dust, soils, water.Soil-borne Cr(III), for example, be oxidized into Cr(VI) incorporated on surface or structure soil during wildfires.Because their extremely small size, high area, reactive sites, control mobilization water; they also threaten human health, primarily through inhalation.However, chemistry Cr(III) oxidation...