Chemistry Commons^™

Characterization Of S-Swcnt/Pf-Pd Dispersions And Networks, Tamara N. El-Hayek Ms., Jeffrey Blackburn, Andrew Ferguson, Tammy Pheuphong

STAR Program Research Presentations

Single-Walled Carbon Nanotubes (SWCNTs) are being investigated for their use in a wide variety of renewable energy applications. Their unique physical properties contribute to desirable traits such as a high carrier mobility, strong optical absorption and tunable electronic band gap. Unfortunately, due to variability in certain parameters, SWCNTs are limited in their application. The major drawback is that SWCNTs are variable in size and type and typical synthetic methods are not selective. As a result, selective methods must be developed in order to sort these tubes and extract those which are desirable for a particular application. Though there are several …

Laboratory Evaluation Of Black Carbon Deposition Onto Snow And Transport Via Snowmelt, Larry D. Hermanson, Joshua P. Schwarz

STAR Program Research Presentations

Black carbon (BC) is an aerosol material produced by incomplete combustion of fossil fuels and biomass. BC has been shown to be the second most important anthropogenic climate warming agent after carbon dioxide due to its ability to absorb solar radiation, influence cloud behavior, and accelerate snow melt. BC in otherwise clean snow can significantly reduce its reflectivity. In order to learn about the significance of BC contamination in snow, we explored the deposition of BC onto snow and the transport of BC in snow during snowmelt. A Single Particle Soot Photometer (SP2), was used to measure the concentration and …

Exploring Soil Moisture Protocol Alternatives For The Classroom Setting, Garrett Smith

STAR Program Research Presentations

Climate change poses a direct threat to future water resources but current climate models suffer from uncertainties regarding the availability of regional water. SMAP or the Soil Moisture Active Passive mission seeks to make improvements to climate models by taking highly accurate, high resolution measurements of global soil moisture. To engage students around the world in a collection of meaningful data that may support the SMAP satellite mission, the Global Learning and Observations to Benefit the Environment program or GLOBE, has forged a partnership with NASA and JPL. GLOBE brings the power of citizen science to the SMAP mission, empowering …

Reduction Of Uranium By Bacterial Products, Adesanya A. Akinleye, Sharon Bone, John Bargar

STAR Program Research Presentations

The Old Rifle Mill Processing site at Rifle, CO, contains uranium contaminated groundwater. The presence of uranium is one of the major problems at Department of Energy legacy sites. There is an initiative for attenuation of uranium by the Department of Energy. Uranium undergoes oxidation/reduction reactions with the substances at the site. Uranium’s oxidation state determines its solubility and mobility in the aquifer. The oxidation reduction pathways at this site have mineralogical, microbial and geochemical components. Understanding the oxidation/reduction pathways of these components will allow for better predictions of the changes and movement of uranium.

Sulfide [S^2- ] and …

The Influence Of Soil Organic Matter Stabilization Mechanisms On Carbon Mean Residence Time Within Various Ecosystems In The United States, Vicky Lynn Giese, Kate Heckman Phd

STAR Program Research Presentations

Some terrestrial ecosystems and soils serve as carbon sinks, partially offsetting rising atmospheric CO₂ levels. Physiochemical mechanisms of soil organic matter (SOM) stabilization affect how carbon stocks respond to global warming. In order to clarify the variance in SOM stabilization mechanisms across different soil types, SOM abundance, distribution and mean residence time (MRT) were compared for thirty-two soil samples from six ecosystems across the United States. Soils were previously described, collected and archived by the United States Geological Survey. Samples were processed by LLNL at the Center for Accelerator Mass Spectrometry (CAMS) using density fractionation to separate particulate organics …

Spectroscopic Study Of Uranium (Vi) Reduction By Plant Biomass, Margaret C. Murphy, John Bargar, Noémie Janot

STAR Program Research Presentations

Uranium is a common and problematic groundwater contaminant at Department of Energy legacy sites. At the former uranium ore processing plant at Rifle, Colorado, sediments rich in decayed plant biomass contain large concentrations of uranium that are slowly being released back to the aquifer. To simulate the reaction that occurs in organic rich sediments of the Rifle aquifer, biomass was incubated in U (VI) bearing groundwater. Carbon X-ray absorption spectroscopy (XAS) was then used to measure if uranium was bound to the biomass. When uranium binds to biomass the peaks in the C XAS spectra will change shape. Uranium L …

Optimizing Electrode Design For Microbial Fuel Cells Used For Wastewater Treatment, Lindsay Nichols, John A. Hogan

STAR Program Research Presentations

Microbial fuel cells (MFC) utilize bacteria to generate an electrical current that can be used in the decomposition of sludge and human urine. In a MFC there is an anode (for oxidation of organic compounds), cathode (reduction of oxygen or carbon dioxide), and a proton exchange membrane (PEM, allows protons to migrate); reduction-oxidation reactions between the anode and cathode produce a measurable current. Bacteria that are found in sludge can be used to produce electrons in a voltaic cell, but optimizing conditions for harnessing the energy is crucial to making a MFC efficient. Research has shown that the ratios of …

Characterization Of Uranium Species In Sediments Under Iron And Sulfate Reducing Conditions Using Synchrotron-Based Techniques, Don Q. Pham, John Bargar

STAR Program Research Presentations

Uranium is one of the most common and problematic contaminants at legacy Department of Energy sites. Groundwater contamination is particularly problematic because it occurs at depth, is present in large volumes, and cannot be easily accessed for clean-up. One method of remediation being investigated is the bioreduction of soluble U(VI) to insoluble U(IV) complexes through the in-situ stimulation of metal-reducing bacteria. Understanding the structure of these uranium complexes can help us determine their fate and stability in groundwater and map out the biological process of uranium reduction by metal-reducing bacteria. In this study, we used the synchrotron-based techniques, X-ray absorption …