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Full-Text Articles in Chemistry

Persistent Organic Chemicals In The Pacific Basin Countries: An Overview, Bommanna G. Loganathan Dec 2016

Persistent Organic Chemicals In The Pacific Basin Countries: An Overview, Bommanna G. Loganathan

Faculty & Staff Research and Creative Activity

The Pacific Basin is a unique geographical region representing tropical, temperate and polar zones. This region is home to 2/3 of world’s population and consists of rapidly growing economies (countries) and highly developed countries. The Pacific Basin countries have had a history of use of persistent organic chemicals (POCs) at varying proportions during the last five decades. Due to diverse climatic and socio-economic conditions, the environment and biota in different countries in this basin have varying degrees of environmental contamination and effects on wildlife and humans. In this chapter, the historical background of POCs including, discovery, production, use, regulations/restrictions imposed, …


Environmental Emission Of Pharmaceuticals From Wastewater Treatment Plants In The Usa, Bikram Subedi, Bommanna G. Loganathan Dec 2016

Environmental Emission Of Pharmaceuticals From Wastewater Treatment Plants In The Usa, Bikram Subedi, Bommanna G. Loganathan

Faculty & Staff Research and Creative Activity

The residual drugs, drug bioconjugates, and their metabolites, mostly from human and veterinary usage, are routinely flushed down the drain, and enter wastewater treatment plants (WWTP). Increasing population, excessive use of allopathic medicine, continual introduction of novel drugs, and existing inefficient wastewater treatment processes result in the discharge of large volumes of pharmaceuticals and their metabolites from the WWTPs into the environment. The effluent from the WWTPs globally contaminate ~25% of rivers and the lakes. Pharmaceuticals in the environment, as contaminants of emerging concerns, behave as pseudo-persistent despite their relatively short environmental half-lives in the environment. Therefore, residual levels of …


Interactions In The Cpsrp Dependent Targeting Of Light Harvesting Chlorophyll Binding Protein To The Thylakoid Membrane, Rory Henderson Dec 2016

Interactions In The Cpsrp Dependent Targeting Of Light Harvesting Chlorophyll Binding Protein To The Thylakoid Membrane, Rory Henderson

Graduate Theses and Dissertations

Targeting of proteins is a critical component of cellular function. A universally conserved targeting system of the cytosol utilizes a signal recognition particle (SRP) to target many proteins contranslationally to the endoplasmic reticulum in eukaryotes or the inner membrane in prokaryotes. A homologous SRP system exists in the chloroplast that delivers light harvesting chlorophyll binding proteins (LHCP) to they thylakoid membrane. The chloroplast SRP (cpSRP) is a heterodimer composed of a novel 43 kDa subunit and a 54 kDa subunit homologous to a component of the SRP system, SRP54. Many details regarding the interactions between the proteins of the cpSRP …


A Pes Study Of Factors Influencing Metal Partitioning In Aquatic Systems: “Design Of Experiment As, Cd, Co, Cr, Cu, Pb, Ni, And Zn”, Eid A. Alkhatib, John Rapaglia, Leon Theim Dec 2016

A Pes Study Of Factors Influencing Metal Partitioning In Aquatic Systems: “Design Of Experiment As, Cd, Co, Cr, Cu, Pb, Ni, And Zn”, Eid A. Alkhatib, John Rapaglia, Leon Theim

Chemistry & Physics Faculty Publications

Mobility and bioavailability of heavy metals are related to their partitioning amongst suspended sediment and water. A Particle Entrainment Simulator (PES) is used to simulate sediment resuspention in natural surface water systems. The simulations were carried out under various conditions of water/suspended solids conditions. Five factors, each at various levels, are tested collectively: the pH of water at two levels (4 and 8), shear stress on bottom sediment at three levels (0.1, 0.3, and 0.5 N/m2 ) salinity of water at two levels (0.01 and 14.0 ppt), organic matter in sediment at three levels (0.50, 1.93, and 3.80%) and temperature …


Green Chemistry: Progress And Barriers, Sarah A. Green Oct 2016

Green Chemistry: Progress And Barriers, Sarah A. Green

Michigan Tech Publications, Part 1

Green chemistry can advance both the health of the environment and the primary objectives of the chemical enterprise: to understand the behavior of chemical substances and to use that knowledge to make useful substances. We expect chemical research and manufacturing to be done in a manner that preserves the health and safety of workers; green chemistry extends that expectation to encompass the health and safety of the planet. While green chemistry may currently be treated as an independent branch of research, it should, like safety, eventually become integral to all chemistry activities. While enormous progress has been made in shifting …


Characterization Of S-Swcnt/Pf-Pd Dispersions And Networks, Tamara N. El-Hayek Ms., Jeffrey Blackburn, Andrew Ferguson, Tammy Pheuphong Oct 2016

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 …


A Complex Legacy Of Contamination In Urban Estuarine Systems, Michael A. Kruge Sep 2016

A Complex Legacy Of Contamination In Urban Estuarine Systems, Michael A. Kruge

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Industrialized urban waterways have typically suffered decades of contamination, varying in source and intensity as manufacturing and transportation practices evolved. The U.S. Environmental Protection Agency designates locales with particularly severe contamination as Superfund sites. Among these, the Gowanus Canal and lower Passaic River in the New York/New Jersey harbor estuary illustrate a complex range of contamination types.

The 2.2 km Gowanus Canal, with sluggish circulation driven mostly by tides, accumulated fine-grained sediments (average thickness of 3 m) highly enriched in organic carbon (OC, mean 11 % but up to 49 %) derived from hydrocarbons, sewage, coal, char, and biomass, along …


Expanding The Applicability Of Raman Spectroscopy For Monitoring Photocatalytic Degradation, Franklyn Wallace Sep 2016

Expanding The Applicability Of Raman Spectroscopy For Monitoring Photocatalytic Degradation, Franklyn Wallace

Mahurin Honors College Capstone Experience/Thesis Projects

Compared to other types of wastewater pollutants, dangerous chemical compounds such as pharmaceuticals, pesticides, and herbicides are difficult to remove and consequently being detected (at least in part because detection limits have decreased) in drinking water at increasing concentrations. Photocatalytic degradation degrades harmful compounds to innocuous end products using energy from light. Although it is effective and cost-efficient, the underlying chemical mechanisms are not understood well enough to ensure that dangerous intermediate products are not formed during the degradation process. Raman spectroscopy can be used to analyze photocatalytic degradation reactions in real time, identifying intermediate products based on spectral features. …


A Comparison Of Solvent And Water-Borne Alkyd Coatings And The History Of Voc Regulations In The United States, Molly Elise Burns Sep 2016

A Comparison Of Solvent And Water-Borne Alkyd Coatings And The History Of Voc Regulations In The United States, Molly Elise Burns

Master's Theses

A Comparison of Solvent and Water-Borne Alkyd Coatings Abstract

Conventional solvent based alkyd coatings have gone out of favor due to concerns over volatile organic compound (VOC) content. However, due to recent focus on renewable raw materials, alkyds are making a comeback in waterborne form. Water based alkyd coatings are known to have poor shelf stability and corrosion resistance, as well as other problems during the formulation process. This project focused on comparing solvent borne to two types of water-borne alkyds, water reducible alkyds and alkyds emulsions. The purpose was to understand the differences between the three types of alkyds …


Persistence Of Trace Organic Contaminants From A Commercial Biosolids-Based Fertilizer In Aerobic Soils, Travis A. Banet, Jihyun R. Kim, Michael L. Mashtare Aug 2016

Persistence Of Trace Organic Contaminants From A Commercial Biosolids-Based Fertilizer In Aerobic Soils, Travis A. Banet, Jihyun R. Kim, Michael L. Mashtare

The Summer Undergraduate Research Fellowship (SURF) Symposium

Municipal biosolids are recycled as agricultural fertilizers. Recent studies have raised concerns due to the presence of emerging contaminants in municipal biosolids. Previous research suggests that these contaminants have the potential to reside in biosolids-based fertilizers that are commercially distributed. Use of these products in urban/suburban areas may provide a pathway for these contaminants to enter ecosystems and impact human and environmental health. Soils from Purdue University’s community garden and MiracleGro Potting Mix were chosen to represent commonly used urban/suburban growth media. Triclosan, triclocarban, and methyl parabens were selected as compounds of interest for this study. A heat treated commercial …


The Role Of Organic Matter In The Fate And Transport Of Antibiotic Resistance, Metals, And Nutrients In The Karst Of Northwest Arkansas, Victor Lee Roland Ii Aug 2016

The Role Of Organic Matter In The Fate And Transport Of Antibiotic Resistance, Metals, And Nutrients In The Karst Of Northwest Arkansas, Victor Lee Roland Ii

Graduate Theses and Dissertations

Organic matter (OM) in the environment acts as a nutrient, but may also act as a transport vector for harmful chemical compounds and bacteria. Acetate is a labile form of OM produced during fermentation in anaerobic lagoons used to store animal fecal-waste from concentrated animal feeding operations (CAFOs). Dry and liquid fertilizers from CAFOs pose a threat to groundwater by introducing excessive amounts of nutrients (e.g. OM, nitrate and ammonia), metals, and antibiotic compounds. In the epikarst of Northern Arkansas in the Buffalo River watershed additional input of labile dissolved organic carbon (DOC) from liquid CAFO waste-fertilizers was hypothesized to …


Multiple New-Particle Growth Pathways Observed At The Us Doe Southern Great Plains Field Site, Anna L. Hodshire, Michael J. Lawler, Jun Zhao, John Ortega, Coty Jen, Taina Yli-Juuti, Jared F. Brewer, Jack K. Kodros, Kelley C. Barsanti, Dave R. Hanson, Peter H. Mcmurry, James N. Smith, Jeffery R. Pierce Jul 2016

Multiple New-Particle Growth Pathways Observed At The Us Doe Southern Great Plains Field Site, Anna L. Hodshire, Michael J. Lawler, Jun Zhao, John Ortega, Coty Jen, Taina Yli-Juuti, Jared F. Brewer, Jack K. Kodros, Kelley C. Barsanti, Dave R. Hanson, Peter H. Mcmurry, James N. Smith, Jeffery R. Pierce

Civil and Environmental Engineering Faculty Publications and Presentations

New-particle formation (NPF) is a significant source of aerosol particles into the atmosphere. However, these particles are initially too small to have climatic importance and must grow, primarily through net uptake of low volatility species, from diameters ∼ 1 to 30–100 nm in order to potentially impact climate. There are currently uncertainties in the physical and chemical processes associated with the growth of these freshly formed particles that lead to uncertainties in aerosol-climate modeling. Four main pathways for new-particle growth have been identified: condensation of sulfuric-acid vapor (and associated bases when available), condensation of organic vapors, uptake of organic acids …


Possible Sources And Impacts Of Biochar Water Extractable Organic Compounds On Aquatic Microorganisms, Cameron Russell Smith Jul 2016

Possible Sources And Impacts Of Biochar Water Extractable Organic Compounds On Aquatic Microorganisms, Cameron Russell Smith

Chemistry & Biochemistry Theses & Dissertations

Smokeless biomass pyrolysis with application of biochar as a soil amendment could be a significant approach for carbon sequestration to possibly control climate change for energy and environmental sustainability. If biochar were to be utilized as a soil amendment and a carbon sequestration agent at Gt C scales, the release of potentially toxic compounds into soils and associated hydrological systems, through soil rainwater runoff and leaching, might have negative consequences, in both agro-ecosystems and aquatic environmental systems. Therefore, the main focus of this dissertation was to study the sources and chemical composition of biochar water extractable (soluble) organic compounds and …


Aqueous Photochemistry Of Glyoxylic Acid, Alexis J. Eugene, Sha-Sha Xia, Marcelo I. Guzman Jun 2016

Aqueous Photochemistry Of Glyoxylic Acid, Alexis J. Eugene, Sha-Sha Xia, Marcelo I. Guzman

Chemistry Faculty Publications

Aerosols affect climate change, the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. While the formation of secondary organic aerosols (SOA) from gas phase precursors is relatively well understood, studying aqueous chemical reactions contributing to the total SOA budget is the current focus of major attention. Field measurements have revealed that mono-, di-, and oxo-carboxylic acids are abundant species present in SOA and atmospheric waters. This work explores the fate of one of these 2-oxocarboxylic acids, glyoxylic acid, which can photogenerate reactive species under solar irradiation. Additionally, the dark thermal aging …


Carbon Nanotubes Affect The Toxicity Of Cuo Nanoparticles To Denitrification In Marine Sediments By Altering Cellular Internalization Of Nanoparticle, Xiong Zheng, Yinglong Su, Yinguang Chen, Rui Wan, Mu Li, Haining Huang, Xu Li Jun 2016

Carbon Nanotubes Affect The Toxicity Of Cuo Nanoparticles To Denitrification In Marine Sediments By Altering Cellular Internalization Of Nanoparticle, Xiong Zheng, Yinglong Su, Yinguang Chen, Rui Wan, Mu Li, Haining Huang, Xu Li

Department of Civil and Environmental Engineering: Faculty Publications

Denitrification is an important pathway for nitrate transformation in marine sediments, and this process has been observed to be negatively affected by engineered nanomaterials. However, previous studies only focused on the potential effect of a certain type of nanomaterial on microbial denitrification. Here we show that the toxicity of CuO nanoparticles (NPs) to denitrification in marine sediments is highly affected by the presence of carbon nanotubes (CNTs). It was found that the removal efficiency of total NOX-N (NO3-N and NO2-N) in the presence of CuO NPs was only 62.3%, but it …


Conversion Of Cafo Manure Into A Slow-Release Fertilizer, Richard Allan Williams Iii May 2016

Conversion Of Cafo Manure Into A Slow-Release Fertilizer, Richard Allan Williams Iii

Honors Projects

Alginate polymer is known to form gel through the process of Ionotropic gelation. By use of extrusion and diffusion setting manure was encapsulated into gel beads. These beads were then tested to determine their potential for further testing as a manure treatment process. From the limited data in this preliminary study, it appears as though there is potential for further testing of alginate beads as a treatment process for manure. The treatment is potentially valuable because of the ease of filtration of the alginate beads, the low cost of transportation of the dehydrated beads, and because the limited data suggests …


Effects Of Cigarette Butts On Coastal Waters: An Elemental Analysis Of Seawater From St. Simon’S Island, Katherine Adorati May 2016

Effects Of Cigarette Butts On Coastal Waters: An Elemental Analysis Of Seawater From St. Simon’S Island, Katherine Adorati

Honors Theses

Cigarette litter can have detrimental effects on the environment, specifically when taking into account that over 4.5 trillion cigarette butts are littered every year. Within seawater, trace elements present in cigarettes may leach into the ocean, having damaging effects on the marine ecosystem. The goal of this research was to investigate if elemental contaminants leached from cigarette litter are significant in samples of seawater collected near St. Simon’s Island at both high and low tides, surrounding a beach party during the Florida/Georgia football game which occurred on November 1, 2014. Samples were collected in the months prior to and during …


Immobilization Of Heteropolyacids In Silica Gel, Opeyemi Adetola May 2016

Immobilization Of Heteropolyacids In Silica Gel, Opeyemi Adetola

Electronic Theses and Dissertations

Silica gels containing incorporated heteropolyacids (HPAs) were synthesized in acidic media by co-condensation of tetraethoxysilane (TEOS) with phosphotungstic or phosphomolybdic acids using sol-gel technique. Effect of the synthesis conditions on their structure and morphology was studied. Yields of modified materials were some lower as compared to non-modified silica gels. All materials were mesoporous but contained micropores in their structures. Presence of bands of Keggin’s structures in FT-IR spectra along with absence of XRD patterns of crystalline HPAs confirmed their fine incorporation into silica network. Particle sizes of modified materials were 800-1100 nm excepting for W-containing sample obtained with trimethylstearylammonium chloride. …


Catalytic Transfer Hydrogenation Of Nitroalkenes To Primary Amines, Brendan Phillips Apr 2016

Catalytic Transfer Hydrogenation Of Nitroalkenes To Primary Amines, Brendan Phillips

Chemistry Honors Papers

This work describes synthetic methodology development in organic chemistry. The goal of this work is to demonstrate new ways of making biologically-relevant molecules that are in line with the principles of green chemistry (chemical practices which seek to be, regarding human and environmental health, benign by design). To this end, a new method has been developed toward the introduction of primary amine functionalities into organic molecules from readily-available aldehydes, via reduction of nitroalkene intermediates. Traditional methods of reducing nitroalkenes to primary amines require harsh conditions, often produce stoichiometric amounts of metal salt waste, and present significant safety challenges to the …


The Level Of Polyaromatic Hydrocarbon Contamination On The Kalamazoo River Shoreline Remains High Following The 2010 Enbridge Oil Spill, Wisam Abdulabbas Flayyih Al Isawi Apr 2016

The Level Of Polyaromatic Hydrocarbon Contamination On The Kalamazoo River Shoreline Remains High Following The 2010 Enbridge Oil Spill, Wisam Abdulabbas Flayyih Al Isawi

Research and Creative Activities Poster Day

  • One of the nation’s worst inland oil spills occurred near Marshall in Michigan in 2010.
  • The recent Enbridge Line 6B rupture released over three million liters of diluted bitumen crude oil into the environment.
  • The spilled oil entered the Talmadge Creek and flowed into the Kalamazoo River, a Lake Michigan tributary.
  • Polycyclic Aromatic Hydrocarbons (PAHs) together with other pollutants were released into the environment.
  • PAHs represents significant threats to aquatic organisms due to their carcinogenic and mutagenic properties and their persistence in the environment.
  • Five years following the oil spill accident, the levels and identities of PAHs were investigated in …


Photocatalytic Reduction Of Fumarate To Succinate On Zns Mineral Surfaces, Ruixin Zhou, Marcelo I. Guzman Apr 2016

Photocatalytic Reduction Of Fumarate To Succinate On Zns Mineral Surfaces, Ruixin Zhou, Marcelo I. Guzman

Chemistry Faculty Publications

The reductive tricarboxylic acid (rTCA) cycle is an important central biosynthetic pathway that fixes CO2 into carboxylic acids. Among the five reductive steps in the rTCA cycle, the two-electron reduction of fumarate to succinate proceeds nonenzymatically on the surface of photoexcited sphalerite (ZnS) colloids suspended in water. This model reaction is chosen to systematically study the surface photoprocess occurring on ZnS in the presence of [Na2S] (1–10 mM) hole scavenger at 15 °C. Experiments at variable pH (5–10) indicate that monodissociated fumaric acid is the primary electron acceptor forming the monoprotic form of succinic acid. The following …


Environmental Applications Of Chromatography-Mass Spectrometry, Wisam Abdulabbas Flayyih Al Isawi Apr 2016

Environmental Applications Of Chromatography-Mass Spectrometry, Wisam Abdulabbas Flayyih Al Isawi

Masters Theses

Gas chromatography-mass spectrometry (GC-MS) and liquid chromatographymass spectrometry (LC-MS) are powerful analytical techniques that combine the separation power in a stationary phase with the detection power of mass spectrometry. GCMS and LC-MS have gained dominant positions in identifying and quantifying different analyte species due to their high selectivity, high sensitivity, and high reproducibility.

My research utilizes the analytical power of LC-MS and GC-MS to address two environmental issues: 1) Identification of biodegradation products of the ionic liquid 1- butyl-3-methylimidazolium chloride (BMIMCl) by an activated sludge microbial community using LC-MS and 2) identification and quantification of polycyclic aromatic hydrocarbons (PAHs) in …


One Year Later: The Politics And Stories Of Post-Earthquake Nepal, Boyer Andrew Apr 2016

One Year Later: The Politics And Stories Of Post-Earthquake Nepal, Boyer Andrew

Independent Study Project (ISP) Collection

A 7.8 magnitude earthquake struck Nepal on April 25th, 2015. This was followed by a second major earthquake of magnitude 7.3 on May 12th , 2015. These disasters took the lives of thousands of Nepali people, destroyed hundreds of thousands of structures, and displaced an estimated two million people. Immediately following the disaster, there was an outpouring of humanitarian aid from around the world. This lead to a conference where $4.1 billion USD of reconstruction funds were pledged to Nepal by international donors. Five months later, a new constitution passed into law and an informal blockade of …


Removal Of Perfluorooctanoic Acid From Water Using Primitive, Conventional And Novel Carbonaceous Sorbent Materials, Christopher K. Brown Mar 2016

Removal Of Perfluorooctanoic Acid From Water Using Primitive, Conventional And Novel Carbonaceous Sorbent Materials, Christopher K. Brown

Theses and Dissertations

Polyfluoroalkyl Substances (PFAS), like perfluorooctanoic acid, have been used for the last 50 years in a wide variety of industrial processes and consumer-based products, including polymer additives, lubricants, fire retardants and suppressants, pesticides, and surfactants (Buck et al. 2015). The Department of Defense (DoD) has used PFAS-based Aqueous Film Forming Foam (AFFF) at fire training facilities and aircraft hangars. AFFF has contaminated approximately 600 sites classified as fire training facilities with PFAS (Huang, 2013).

This study focused on testing the most likely carbonaceous adsorbent compounds to remediate PFAS-contaminated sites on Air Force installations. Batch tests were performed to determine the …


Sulfur-Mediated Photochemical Energy Harvesting In Nanoporous Carbons, Alicia Gomis-Berenguer, Mykola Seredych, Jesus Iniesta, Joao C. Lima, Teresa J. Bandosz, Conchi O. Ania Mar 2016

Sulfur-Mediated Photochemical Energy Harvesting In Nanoporous Carbons, Alicia Gomis-Berenguer, Mykola Seredych, Jesus Iniesta, Joao C. Lima, Teresa J. Bandosz, Conchi O. Ania

Publications and Research

This work provides new insights in the field of applied photochemistry based on semiconductor-free nanoporous carbons and its application to sunlight energy harvesting. Using carbon materials of increasing average pore size, chemical functionalization to introduce a variety of O- and S-containing functional groups and monochromatic light, we have shown the dependence of the photochemical conversion of phenol in the confinement of the carbons nanopore space with the wavelength of the irradiation source, the dimensions of the pore voids and their surface chemistry. The photochemical conversion of phenol inside the carbons pore space was found to be very sensitive to the …


Nitrous Oxide In The Atmosphere: First Measurements Of A Lower Thermospheric Source, Patrick E. Sheese, Kaley A. Walker, Chris D. Boone, Peter F. Bernath, Bernd Funke Mar 2016

Nitrous Oxide In The Atmosphere: First Measurements Of A Lower Thermospheric Source, Patrick E. Sheese, Kaley A. Walker, Chris D. Boone, Peter F. Bernath, Bernd Funke

Chemistry & Biochemistry Faculty Publications

Nitrous oxide (N2O) is an important anthropogenic greenhouse gas, as well as one of the most significant anthropogenic ozone-depleting substances in the stratosphere. The satellite-based instrument Atmospheric Chemistry Experiment-Fourier Transform Spectrometer has been observing the Earth's limb since 2004 and derives profiles of N2O volume mixing ratios in the upper troposphere to the lower thermosphere. The resulting climatology shows that N2O is continuously produced in the lower thermosphere via energetic particle precipitation and enhanced N2O is present at all latitudes, during all seasons. The results are consistent with an N2O …


The Effects Of Rain On Elemental Transport In Soils, Laura Schoenfeld Jan 2016

The Effects Of Rain On Elemental Transport In Soils, Laura Schoenfeld

STAR Program Research Presentations

Mini Landscape Evolution Observatory (miniLEO) is a model landscape slope composed of granular basalt used to conduct small scale experiments to more clearly understand how elemental transport occurs during simulated rain events. For this experiment, rain events occurred three times a day in two hour increments at a rate of 30 mm/hr for 14 days to determine if exchangeable ions and target elements dissolve over time. An auto sampler collected the waterseepage every half hour at the bottom of the slope of miniLEO. Each seepage sample was tested or the amount of elements present in solution using ion chromatography and …


Probing The Transport Properties Of Chemically-Doped Single-Walled Carbon Nantotube Polymer Composites, Tammy Pheuphong, Tamara El-Hayek, Jeffrey Blackburn, Andrew Ferguson Jan 2016

Probing The Transport Properties Of Chemically-Doped Single-Walled Carbon Nantotube Polymer Composites, Tammy Pheuphong, Tamara El-Hayek, Jeffrey Blackburn, Andrew Ferguson

STAR Program Research Presentations

Thermoelectric (TE) materials are used to convert waste heat into electrical power. Semiconducting single-walled carbon nanotubes (s-SWCNT) have great potential to be used in thermoelectric devices, either on their own or in composites with conducting polymers. Certain polymers can selectively extract s-SWCNT from raw carbon nanotube soot (containing impurities such as metallic SWCNT, amorphous carbon, metal catalysts particles), but most of these polymers (e.g. polyfluorenes) are electrical insulators, rendering them inefficient in TE nanocomposites. On the other hand, conducting polymers, such as poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), have been used in efficient TE nanocomposites, but have never been rationally designed with …


Methane Emissions As Energy Reservoir: Context, Scope, Causes And Mitigation Strategies, Xiaoli Chai, David J. Tonjes, Devinder Mahajan Jan 2016

Methane Emissions As Energy Reservoir: Context, Scope, Causes And Mitigation Strategies, Xiaoli Chai, David J. Tonjes, Devinder Mahajan

Technology & Society Faculty Publications

Methane (CH4) is now considered a bridge fuel between present fossil (carbon) economy and desired renewables and this energy molecule is projected to play an important role in the global energy mix well beyond 2035. The atmospheric warming potential of CH4 is 28-36 times, when averaged over a 100-year period, that of carbon dioxide (CO2) and this necessitates a close scrutiny of global CH4 emissions inventory. As the second most abundant greenhouse gas (GHG), the annual global CH4 emissions were 645 million metric tons (MMT), accounting for 14.3% of the global anthropogenic GHG emissions. Of this, five key anthropogenic sources: …


Determination Of Hexavalent Chromium (Cr(Vi)) Concentrations Via Ion Chromatography And Uv-Vis Spectrophotometry In Samples Collected From Nacogdoches Wastewater Treatment Plant, East Texas (Usa), Kefa Karimu Onchoke, Salomey A. Sasu Jan 2016

Determination Of Hexavalent Chromium (Cr(Vi)) Concentrations Via Ion Chromatography And Uv-Vis Spectrophotometry In Samples Collected From Nacogdoches Wastewater Treatment Plant, East Texas (Usa), Kefa Karimu Onchoke, Salomey A. Sasu

Faculty Publications

The concentration of hexavalent chromium (Cr(VI)), a toxic environmental pollutant and carcinogen, was determined in samples collected from Nacogdoches Wastewater Treatment Plant (NWWTP) using ion chromatography and UV-visible spectrophotometry (IC, UV-Vis). On reaction with 1,5-diphenylcarbazide (DPC) Cr+6 forms a 1,5-diphenylcarbazide-Cr(VI) complex, which is then analyzed at 530nm and 540nm, respectively. Via ion chromatography Cr(VI) concentrations were in the range of 0.00190 ± 0.0020 and 0.0010 ± 0.0006ppm at the influent and effluent, respectively. With the use of standard addition wastewater samples were spiked with a 0.5ppm Cr(VI) standard of various amounts and subsequently analyzed with UV-Vis spectrophotometry. The spiked concentrations …