Student Abstracts: Chemistry

Analysis of Some Near-Infrared Spectra of C2Br. ELIZABETH MILLINGS (Suffolk County Community College, Selden, NY, 11784) DR. TREVOR SEARS (Brookhaven National Laboratory, Upton, NY, 11973)

In combustion chemistry, the C₂H molecule has been studied extensively because it is an important intermediate and provides an example of the breakdown of the Born-Oppenheimer approximation. A related molecule, C₂Br, supplies a different view of the Born-Oppenheimer breakdown, and its rotational, vibrational, and electronic structure can be compared to C₂H. Previously, only computational studies have been reported regarding C₂Br. Its energy states and spectra were theoretically determined, and a model equation was developed to describe its rotational energy levels. Recently, a spectrum of C₂Br was accidentally detected at Brookhaven National Laboratory, and a portion of it was tentatively assigned to some P-branch rotational transitions. In this project, the spectroscopic data were further examined in an attempt to confirm the assignments, determine the rotational constants, identify spectral lines corresponding to the two bromine isotopes, and identify the band origins. To accomplish this, a LabVIEW computer program was developed and used to calculate the energy levels and predict spectra, which were then compared to the experimental near-infrared (NIR) spectra. The error between the data and the calculations was minimized by adjusting the modeling constants and testing possible assignments. A simulated spectrum was created with each new calculation enabling a set of "best fit" values to be determined. This analysis is part of a larger work investigating the chemical processes of combustion by studying the structure and dynamics of intermediate reactive species.

Automation of Chromatographic Separation Procedures. NICK STUCKERT (University of Wyoming, Laramie, WY, 82609) ROSI PAYNE (Pacific Northwest National Laboratory, Richland, WA, 99352)

The purpose of this paper is to provide a detailed discussion of an attempt to automate UTEVA and TRU gravity chromatographic separation procedures. These procedures are used for the chemical separation of radioactive elements prior to analysis. The problems that were encountered will be presented along with solutions and potential solutions to the problems. The methods for leak detection and resolution are presented in addition to a suite of additional minor changes. Some specific suggestions for modifications include the use of flow meters or creating an open system that relies on gravity filtration. In both cases substantial work will be required to develop a working system.

BOB Ionic Liquids: Preparation and Properties. ALEJANDRA CASTANO (Queens College, Flushing, NY, 11367) JAMES WISHART (Brookhaven National Laboratory, Upton, NY, 11973)

Ionic liquids (ILs) are salts that melt below 100 0C. ILs are ideal alternative solvents to work with because they exhibit properties such as thermal stability, non-volatility, combustion resistance, high conductivity, and wide electrochemical windows. Owing to their non-volatility ILs do not contribute to air pollution and they are being investigated for a variety of applications as alternative solvents, including use in nuclear processes. The potential utility of ionic liquids for the processing of radioactive material is being investigated through the use of pulse radiolysis techniques. Ionic liquids containing the Bis(Oxalato)Borate (BOB-) anion are being investigated for this application, because of the neutron scavenging ability of 10boron. Calculations by others have shown that ILs containing boron can be used to handle higher concentrations of fissile material than conventional solvents without the risk of criticality. Halide salts such as 1-methyl-3-pentylimidazolium bromide (C5MIM Br) and a homologous series of pyrrolidinium, and pyridinium types were synthesized using both thermal and microwave-assisted techniques. The halide salts were prepared by reacting the amines with their corresponding alkyl halides. Boron containing ILs were prepared by metathesis reactions with sodium BOB (NaBOB). NaBOB was synthesized by reacting boric acid, oxalic acid and sodium hydroxide in water under reflux conditions. Preliminary results of pulse radiolysis experiments indicate that BOB anion scavenges radiolytically-generated solvated electrons too efficiently for BOB ILs to be stable as neat solvents for processes under ionizing radiation, as in nuclear separations. Thus, only small concentrations of borated ILs such as the BOB salts may be necessary to achieve inherent criticality protection. The salts would be most effective when dissolved in a IL co-solvent such as N-butyl-N-methylpyrrolidiunium bis(trifluoromethylsulfonyl)imide. Further characterizations such as viscosity, melting points, glass transitions, and electrochemical windows are also being investigated. Such data will provide valuable information to facilitate the broader applications of the BOB ILs.

Characterization of GaN, In025Ga075N and In050Ga050N for Photoelectrochemical Water Splitting. SALLY PUSEDE (University of Colorado at Denver and Health Sciences Center, Denver, CO, 80217) TODD DEUTSCH (National Renewable Energy Laboratory, Golden, CO, 89401)

GaN, In_0.25Ga_0.75N and In_0.50Ga_0.50N semiconductors were characterized as possible candidates for photoelectrochemical water splitting. The band gap energies of the materials were measured and found to decrease with increasing indium content. The flatband potential (V_fb) of GaN was determined and the material’s band edges verified to span the potentials of the hydrogen and oxygen evolution reactions; however, the V_fb positions of In_0.25Ga_0.75N and In_0.50Ga_0.50N could not be experimentally established. Two-electrode current density vs. potential measurements of both InGaN materials indicated anodic current flow at zero applied potential considerably below theoretical maxima, suggestive of photocorrosion rather than spontaneous water splitting. Where GaN was observed to be stable, In_0.25Ga_0.75N and In_0.50Ga_0.50N were found to be extremely susceptible to photocorrosion.

Characterization of Non-platinum Electrocatalysts for Polymer Electrolyte Fuel Cells. JAMES GILBERT (University of Illinois at Chicago, Chicago, IL, 60607) XIAOPING WANG (Argonne National Laboratory, Argonne, IL, 60439)

Two of the limiting factors for polymer electrolyte fuel cell (PEFC) development are the cost and supply availability of platinum, which is currently used as the electrocatalyst for both the oxygen reduction reaction (ORR) and the fuel oxidation reaction. The goal of this project is to develop ORR catalysts that do not contain platinum, are less expensive, and offer comparable ORR activity to platinum-based catalysts. In this work, a testing procedure was established to evaluate ORR activity by using commercial platinum and non-platinum electrocatalysts and using cyclic voltammetry with a rotating disk electrode setup that is used for correction for mass transport contribution. The non-platinum catalysts studied were different compositions of a palladium-based bimetallic system supported on carbon that were prepared by impregnation and post-temperature-programmed reduction. Their ORR activity per mass of metal catalyst was determined and compared to that of commercial catalysts. Results show that the alloying of the base metal to the palladium yields a greater activity. The best ORR activity was observed from the atomic ratio of palladium to the base metal of 1:1, with ratios of 9:1 and 3:1 showing improved activity than that of the palladium catalyst alone. This project is part of a larger effort to develop an effective, low-cost, platinum-free cathode catalyst for PEFC technologies. Future work will include a broader characterization of the palladium-based bimetallic catalyst for practical use in a PEFC, along with the study of other palladium-based bimetallic systems.

Characterization of Silicon Carbide for Water-Splitting and Corrosion Protection. BORIS CHERNOMORDIK (University of Louisville, Louisville, KY, 40292) DR. JOHN TURNER (National Renewable Energy Laboratory, Golden, CO, 89401)

Harnessing hydrogen as an energy carrier by means of renewable power, such as solar, is key to achieving a clean and dependable energy cycle. Direct photoelectrolysis of water with photoelectrochemical (PEC) cells is the most efficient method to collect hydrogen from water. In this study, commercial samples of the 4H polytype of silicon carbide (SiC), with n- and p-type doping, were photoelectrochemically characterized with a focus on durability for possible use as a protective coating for chemically sensitive high-efficiency PEC materials. The indirect band gap was found to agree with the literature value of 3.23eV and the bands were found to straddle the water electrolysis redox potentials, with the flat band potential vs. pH relationship exhibiting Nernstian behavior. Corrosion experiments showed that n-type SiC is susceptible to oxidative etching, while p-type SiC did not show signs of corrosion. Though the high band gap renders 4H-SiC inefficient for photoelectrolysis because it absorbs only a tiny portion of the solar spectrum, corrosion experiments suggest that p-type SiC may be durable enough to act as a protective layer in PEC cells. More experimentation in this regard is necessary, though. In addition, more research is needed into methods for incorporating SiC as a protective coating for a high conversion efficiency cell.

Comparing the properties of pyridinium and 4-dimethylaminopyridinium ionic liquids. JASMINE HATCHER (Queens College, Queens, NY, 11590) JAMES WISHART (Brookhaven National Laboratory, Upton, NY, 11973)

Ionic liquids, organic salts that melt below 100°C, are generally composed of a large organic cation and a relatively small inorganic anion. They have generated much interest due to their potential as alternative reaction media for a variety of applications including use in batteries, fuel cells, and for the storage and processing of nuclear waste. Ionic liquids can be designed to incorporate specific functionalities for certain uses ("task-specific ionic liquids"). The physical characterization and properties of 4 dimethylaminopyridnium (DMAP) based ionic liquids with varying functionalities in comparison to their pyridinium (py) analogues are reported here. In addition, this study examines the effect of the dimethylamino group of DMAP on the physical properties of these two series of ionic liquids. The dimethylamino group of DMAP is known to have catalytic properties and DMAP based ionic liquids are expected to have similar properties. The DMAP and pyridinium salts were synthesized using various alkylating agents such as 3-chloropropanol and 2-bromoethyl ethyl ether. The resultant halide salts were converted to ionic liquids bearing bis(trifyl)imide anion. Physical properties investigated include: viscosity, conductivity, and thermal profile. Preliminary results indicate that for both the DMAP and py systems, the ionic liquids containing alkyl groups have lower viscosities and higher conductivities at room temperature compared to those bearing hydroxyl groups. Results also suggest the presence of the dimethyl amino group on the pyridine ring has minimal effect on the conductivity and viscosity. The Butyl DMAP and Butyl Pyridinium ionic liquids had almost the same conductivity (2.12 mS/cm and 2.22 mS/cm respectively) and viscosity (9.950 cP and 9.122 cP at 850C respectively). Future work will focus on the effect of the position of the dimethylamino group on the pyridine ring on the same properties.

Design and Development of Palladium- Iron Bimetallic Electrocatalyst for Polymer Electrolyte Fuel Cells. RICHARD COOK and JESSICA PRICE (Berea College, Berea, KY, 40404) MARK CUNNINGHAM (Argonne National Laboratory, Argonne, IL, 60439)

The path to more efficient energy sources for modes of transportation, to replace the CO2-emitting, low efficiency internal combustion engine, has led The Department of Energy and Argonne National Laboratory to develop commercially competitive polymer electrolyte fuel cells (PEFCs). The purpose of this project is to design and develop bimetallic cathodic electrocatalysts for PEFCs with high electrochemical activity and high stability in order to replace more expensive platinum-based electrocatalysts. The bimetallic electrocatalysts reported in this study are composed of the precious metal palladium (Pd) and the base metal iron (Fe) fixed onto carbon support. The less expensive base metal, iron, is designed to comprise the core of the bimetallic alloy with a monolayer outershell consisting of palladium. The Pd-Fe electrocatalysts were synthesized by the impregnation method, utilizing Fe (NO3)3 and Pd(NO3)2 as metal precursors, producing bimetallic catalysts with a range of metal compositions. The precursor salts were reduced to the Pd-Fe bimetallic electrocatalyst in a dilute hydrogen atmosphere. Transmission electron microscopy, temperature programmed-reduction, and cyclic voltammetry, using the rotating disk electrode, were used to characterize the electrocatalysts’ composition and particle size, reduction conditions for heat treatment, and catalyst stability and performance, respectively. The bimetallic catalyst with a molar ratio of 30:70 (Pd:Fe), heat treated in regen gas at 620 oC for 10 h, showed the highest activity of 65.31 mA/mgPd at 0.85V. Further research will focus on maximizing catalyst performance by optimizing heat treatment conditions to minimize particle size with a core-shell morphology. The desired end result is a bimetallic alloyed electrocatalyst that is cost efficient, has a high rate of oxygen reduction, a small particle size, and an activity of 440 mA/mg metal at 0.9V ( 2010 DOE target).

Determination of Naturally Occurring versus Process Introduced Beryllium at Lawrence Livermore National Laboratory. JENNIFER MULLINS (Randolph-Macon Woman's College, Lynchburg, VA, 24503) RYAN KAMERZELL (Lawrence Livermore National Laboratory, Livermore, CA, 94550)

The Department of Energy (DOE) Title 10 Code of Federal Regulations, Part 850, Chronic Beryllium Disease Prevention Program defines the maximum removable surface contamination of beryllium (Be) in non-Be work areas as the higher of 0.2 µg Be/100cm² or the concentration of Be in soil at the point of release. Be is a naturally occurring metal and can be found on surfaces in concentrations greater than the defined DOE release limit without a process present that would introduce contamination. Until now there has been no standardized method for deciphering between naturally occurring and process introduced Be. The purpose of this research was to develop such a method by determining naturally occurring ratios of Be to other naturally occurring metals in soil at Lawrence Livermore National Laboratory (LLNL). Sixty random soil samples were collected from uncontaminated locations within the LLNL site boundary. The samples were analyzed for the concentrations of Be and 19 other metals using an Inductively Coupled Plasma Spectrometer. Aluminum (Al), nickel (Ni), and vanadium (V) were selected to calculate the naturally occurring ratios based upon detection rates, low variability, and R-values from the Ryan-Joiner W-test for normality. Two-sided 95% upper and lower tolerance limits (UTL and LTL) were calculated for the true 95^th percentile of each naturally occurring ratio: [Be]:[Al]- UTL_97.5%,95% =5.06x10-5, LTL_2.5%,95%=4.35x10^-5, mean=3.40x10^-5; [Be]:[Ni]- UTL_97.5%,95%=1.73x10^-2, LTL_2.5%,95%=1.30x10^-2, mean=8.12x10^-3; and [Be]:[V]- UTL_97.5%,95%=1.63x10^-2, LTL_2.5%,95% =1.38x10^-2, mean=1.05x10^-2. Sample data suggests with 95% confidence that 95% of the ratios do not exceed the true UTL when beryllium is naturally occurring. Future data can be compared to the ratios to conclude the following: (1) if the sample ratio is less than the LTL, the Be is naturally occurring, (2) if the sample ratio is greater than the LTL but less than the UTL, further investigation is required, and (3) if the sample ratio is greater than the UTL, the Be is process introduced. Other DOE sites can use this method to determine their own ratios to discriminate between naturally occurring and process introduced Be. The ability to determine this will allow for redirection of resources away from unnecessarily implementing decontamination requirements for cleaning surfaces with false contamination. Implementing this method would be fiscally responsible while not increasing employee health risk.

Determination of Silica in Uranium Casting Pins Samples by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). MEGAN LONGO (Albertson College of Idaho, Caldwell, ID, 83605) DR. JEFFREY GIGLIO (Idaho National Laboratory, Idaho Falls, ID, 83415)

An analytical method was developed for the determination of Silica (Si) in Uranium casting pins. The new method utilized an Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) for the determination of Si at 250.69 nm and 251.611 nm. The Si lines yielded instrument detection limits (3s) of 0.007 and 0.02 µg/mL, respectively. The method detection limits for the new analytical method are 50 µg/g in the solid. An interfering element correction had to be employed because of a spectral interference from U. The U concentration in the solutions analyzed by ICP-AES was approximately 1150 µg/mL. Spiked sample recoveries yielded complete recoveries, within the experimental error of the analysis. The new ICP-AES method was compared to a molybdenum blue colorimetric method. Results were comparable, within the experimental error of both measurements.

Determining the Extent of Delocalization in Mixed-Valence Iron Dimers Using x-ray Absorption Spectroscopy. ALISON HOYT (Yale University, New Haven, CT, 06520) KELLY GAFFNEY (Stanford Linear Accelerator Center, Stanford, CA, 94025)

This study examines the extent of charge delocalization in mixed valence compounds. Understanding the structure of charge delocalization is the first step in understanding the local dynamics of charge transfer. This insight has diverse applications such as the ability to mimic biological reactions and to enhance solar technology. Because of its fast time scale, synchrotron radiation was used to probe the iron K-edge for three organometallic systems. In these complexes, two bridged metal atoms share an effective charge of 5+. In a Robin-Day Class II compound, charge is localized and the two iron atoms have effective oxidation states of 2+ and 3+ respectively. For Class III delocalized compounds each metal center has an effective charge of 2.5+. Class II/III compounds exhibit characteristics of both localized and delocalized systems according to various optical spectroscopies. Synchrotron radiation was used to study charge distribution in these poorly-understood Class II/III intermediate systems. In the limit of absolute localization, spectra of the mixed valence species were expected to be a linear combination of the reduced and oxidized species. For the delocalized case, a linear combination was not expected. These two cases were used as calibration limits to determine the extent of delocalization in the unknown Class II/III compound. Results showed that synchrotron radiation classifies the Class II/III compound as localized. However, data also demonstrated that the linear combination model did not hold as expected and a revised model is necessary to better understand this phenomenon.

Determining the Local Structure of Platinum Streptidine using X-Ray Absorption Spectroscopy. MICHAELLE MAYALU (Massachusetts Institute of Technology, Cambridge, MA, 02139) SERENA DEBEER GEORGE (Stanford Linear Accelerator Center, Stanford, CA, 94025)

X-Ray absorption spectroscopy (XAS) is a technique that utilizes high energy X-rays commonly obtained from synchrotron radiation to determine the structure of known and unknown substances and materials. By examining the absorption vs. energy pattern, one can determine the local structure surrounding the absorbing atom. Analysis of a region of the absorption vs. energy graph called extended x-ray absorption fine structure (EXAFS) leads to information about the identity of the atoms surrounding the absorber, the number of atoms surrounding the absorber, and the distances between the absorber and neighboring atoms. Using XAS, structural descriptions of platinum streptidine, a newly synthesized platinum anti-cancer agent, have been obtained. The results show that the platinum is in fact coordinated to the streptidine, which was the main question that needed to be answered about the drug.

Calbindin, a metalloprotein with two calcium binding sites, is present in multiple species and involved in biological processes as varied as calcium transport in fruit fly neurons and mammalian intestinal calcium uptake. Despite its ubiquity, its biological roles, and binding behavior are unknown. This paper focuses on the preparation of 9 kDa calbindin for solid state nuclear magnetic resonance (ssNMR) spectroscopy. Our purified calbindin will be used for the first ssNMR experiments studying calcium within a protein. To best understand the structure and mechanisms of calbindin’s binding sites, each site must be studied separately. To accomplish this, two calbindin mutants were to be prepared for ssNMR spectroscopy. Each mutant had been altered so that only one binding site retained its original structure and function. A synthetic gene was inserted into a pET expression system to produce calbindin mutants using Escherichia coli. After harvesting the cells, protein was purified primarily with ion exchange and gel filtration chromatography. However, several analyses using SDS-PAGE Tris-tricine and Tris-HCl gels made it evident that D9K P43M E65Q was not expressing well in E. coli BL21(DE3) or E. coli BL21(DE3) pLysS competent cells. Instead, we then purified calbindin D9K P43M, which had both binding sites intact. The ssNMR spectrum of a previously made calcium binding mutant E27Q P43M can be removed from that of calbindin D9K P43M, still allowing for study of the other calcium binding site. Though purification of the initial calbindin double mutant P43M E65Q was found unfeasible, a combination of earlier calbindin purification procedures were successfully adapted to purifying D9K P43M to homogeneity as determined by SDS-PAGE. With the aid of a fermentation unit, these methods should be easily scaled up to produce the required quantities needed for planned ssNMR experiments.

Dynamics of Fast Reactions in Ionic Liquids. KATHRYN SIMS and KANDIS STUBBLEFIELD (Howard University, Washington, DC, 20059) DR. JAMES WISHART (Brookhaven National Laboratory, Upton, NY, 11973)

Ionic liquids (ILs) are liquids consisting of ions and have melting points below 100 °C. Used in technologies and green chemistry they are being considered as processing media in the advanced nuclear fuel cycles needed to support a sustainable nuclear power industry for the world’s future energy needs. It is important to understand the radiation-induced chemistry of ILs and how it may affect the chemistry of nuclear fuel separation. The unique reactivity of the "pre-solvated" electron surfaces as an important aspect of radiation chemistry due to the slower response to charge movement in ionic liquids relative to ordinary solvents. This study explores the reactivity of pre-solvated electrons in the ionic liquid N-methyl N-butylpyrrolidinium NTf2 (P14NTf2) by measuring the kinetics of their reactions with cadmium, nitrate and selenate ions. These ions were selected because they show a wide range of reactivities with electrons in conventional solvents. The process of electron solvation, which competes with pre-solvated electron capture, is estimated by measuring the benzophenone anion solvation process because its spectroscopic properties are better suited to the available detection equipment than those of the electron. The Brookhaven National Laboratory (BNL) Laser Electron Accelerator Facility (LEAF) was used for all of the kinetics measurements performed by pulse radiolysis transient absorption spectroscopy. The C37 parameter was obtained to look at the lower concentration of benzophenone. Higher concentrations were also analyzed to allow us to look at the spectral shifts and compare them to that of the selected ions in the IL. In conclusion, we have determined the reaction kinetics of fast reactions in the IL.

Effect of Solvent Box Size on Wide-Angle X-ray Scattering Patterns. HEATHER SUTTON (Chicago State University, Chicago, IL, 60628) DAVID M. TIEDE (Argonne National Laboratory, Argonne, IL, 60439)

Wide-angle x-ray scattering (WAXS) has been presented as an alternative method to the use of x-ray diffraction and nuclear magnetic resonance (NMR) for experimental structural verification of solution-phase macromolecular assemblies. Use of WAXS to determine solution structure requires comparison of the experimental scattering patterns to scattering patterns produced by molecular models. One approach for producing these models is to use structures produced during explicit solvent molecular dynamics (MD) simulations. These simulations place the solute in a bath (a box or sphere shape is most common) of explicit solvent molecules. Prior work has focused on the solute scattering, removing all solvent molecules before the x-ray scattering pattern is computed, thus ignoring all solvent scattering. The long-term goal of this work is to extend the simulation model approach by including solvent in the scattering calculation in order to investigate the structure of solvent around porphyrin solutes. However, the finite size of the simulation solvent box results in artificial x-ray scattering. The present goal of this work is to facilitate treatment of solvent in MD simulations by determining adequate solvent box size to prevent the appearance of edge scattering peaks within our range of interest in the calculated scattering pattern. Solvate baths of various sizes and shapes were created using the solvate tool in visual molecular dynamics (VMD). After equilibration, constant energy (nve) simulations were run on these solvation boxes using the CHARMM force-field. Coordinates of these simulations were Fourier transformed to produce the calculated scattering patterns. These calculated scattering patterns have shown that the edge-scattering peaks can not be eliminated by increasing the size of the solvation box. However, spherical solvation baths have an analytic form for the edge scattering allowing the "false" scattering peaks to be subtracted off. These spherical baths will be used to study the solvent/solute interactions of porphyrin systems. Additionally, this work suggests that the TIP3 water model is accurate enough to use in further simulation work. In contrast, the charmm 22 toluene parameters will need to be adjusted before being used to model toluene/porphyrin interactions. The usage of WAXS data combined with simulation will provide, for the first time, a means to achieve this re-parameterization that is directly linked to experimental data.

Effects of the Porphyrin Oxidation State on the Conformation of C-type Cytochromes. TIM VUONG (Chicago State University, Chicago, IL, 60628) KRISTY L. MARDIS (Argonne National Laboratory, Argonne, IL, 60439)

The increase in natural gas and oil prices has sparked renewed interest in alternative fuel sources such as solar energy. C-type cytochromes, found in a variety of bacteria, plants, and animals are being studied as possible building blocks for solar energy devices. Their usage depends on electron transfer (ET). To make these proteins suitable for ET devices, their solution conformation must be determined. Experimental wide-angle x-ray scattering (WAXS) studies have found that the c-type cytochrome (Protein Data Bank entry 1os6), extracted from the Geobacter genome and expressed in Escherichia coli, has identifiably different conformations in the reduced and oxidized form. The current work seeks to determine if the Chemistry of Harvard Molecular Modeling (CHARMM) force field can reproduce the experimental scattering pattern. This protein was chosen because (1) experimental scattering data are available and (2) it has three heme sites making the effect of oxidizing or reducing the iron in the center of the site larger than for proteins with single hemes. Calculations of the scattering profile were accomplished using structures obtained from crystal structure data. These starting structures were then subjected to nanosecond scale molecular dynamics simulations in a water sphere (radius = 30 Angstroms). The scattering profiles were obtained as the Fourier transform of the atomic coordinates. The scattering profiles calculated from the ensemble of structures for both the oxidized and reduced structures were then compared to the experimental data. Preliminary results indicate that the CHARMM 22 force field does distinguish between the oxidized and reduced forms of the protein. However, longer simulations are required before the results can be directly compared to experiment. The results will indicate the ability of the CHARMM forcefield to distinguish between two proteins differing only in the charge state of the irons in the three heme groups.

Electrochemical Arsenic Remediation of Drinking Water in Rural Bangladesh. YOLA BAYRAM (University of Michigan-Dearborn, Dearborn, MI, 48128) ASHOK GADGIL (Lawrence Berkeley National Laboratory, Berkley, CA, 94720)

According to the World Health Organization, in Bangladesh over 60 million people drink arsenic-laden water making it the largest case of mass poisoning in human history. Available methods of treating arsenic are too expensive, ineffective, or commonly difficult to implement, making them unsuitable for a poor or undeveloped country such as Bangladesh. Electrochemistry may provide an innovative, effective, and inexpensive method for arsenic remediation of drinking water. The method is an improvement upon a known method of using Fe(III) to remove arsenic. The Fe(III) combines with As(V), forming an insoluble complex which then can be easily filtered out. The innovative step of electrochemistry allows control over the amount of Fe(III) produced as well as electrochemical oxidation of the As(III) into reactive As(V) anion, making the method far more effective. Experiments were performed with water samples with 600ppb of total arsenic that received currents of 70mA and 110mA for varying durations of time. The objective is to determine the appropriate current and time necessary for an arsenic removal above 99% in order to meet WHO standards. Experimental results showed that using a current of 110mA for 11 minutes showed a removal rate from 98-100%. This same current and length of time also oxidized 96-100% of As(III) to As(V). Once the process is well understood and the electrochemical variables are optimized, the method will be applied to a practical water filter. The hope is that this filter will be applied in Bangladesh and other areas affected by arsenic poisoning to provide millions of people with safe drinking water and an improved standard of living.

Electrochemical Remediation of Arsenic Contaminated Groundwater. KRISTIN KOWOLIK (University of California, Berkeley, Berkeley, CA, 94704) ASHOK GADGIL (Lawrence Berkeley National Laboratory, Berkley, CA, 94720)

Millions of people worldwide do not have access to clean water. This problem is especially severe in Bangladesh where water is severely contaminated with arsenic. Chronic arsenic exposure has devastating health effects: cardiovascular diseases, cancers, and eventually death. Many methods of arsenic removal have been studied but most of these are too expensive and impractical to be implemented in poor countries such as Bangladesh. This project investigates electrochemistry as an affordable means of removing arsenic. Experiments are performed using a whisk like device made out of iron as the cathode and copper as the anode. Both electrodes are immersed in simulated groundwater spiked with an arsenic concentration of 600 ppb. During voltage application, currents of 70 mA and 110 mA are passed through the system. The water is stirred gently to ensure uniform electron distribution. While the electrochemical process is progressing, iron metal is oxidized to Fe(III). As an ionic species, iron will bind free arsenic in solution. After the desired amount of charge is passed, the treated water is allowed to precipitate for 24 hours and is then filtered by means of vacuum filtration. One of the significant major tasks of the project was to develop an experimental protocol (methods, measurement techniques, experimental conditions) to obtain proof of concept, so this process can be investigated further. We showed that if certain conditions are met such as (1) optimal charge per volume, (2) optimal current density and (3) precipitation time of 24 hours, promising results are obtained. An initial arsenic concentration of 600 ppb can be reduced to a final concentration of 50 ppb in 2.5 L water by application of 70.08 C/L at 70 mA and 107.5 C/L at 110 mA. These results are very encouraging and provide great promise that electrochemistry is a powerful, and most importantly, an affordable tool in the remediation of arsenic from contaminated groundwater.

Electrolysis of Saline for pH Control and Oxygen Production. ANNA BESMANN (University of North Carolina at Asheville, Asheville, NC, 28804) ELI GREENBAUM (Oak Ridge National Laboratory, Oak Ridge, TN, 37831)

Diabetic retinopathy is a disease which causes small, fragile blood vessels to form within the retina to compensate for the normal blood vessels’ inability to bring sufficient oxygen to the eye. These blood vessels are prone to hemorrhaging in the eye, causing temporary or permanent blindness. To help stop this problem before the small blood vessels can form, electrodes can be implanted into the eye to stimulate the production of oxygen in the vitreous humor. However, this also induces the formation of free chlorine, which causes the vitreous humor to become more alkaline. In order to keep the pH at a manageable level, an anode and a cathode can be implanted into the vitreous humor while a second anode connected to both electrodes by a sidearm can be implanted behind the ear. Protons will pass back and forth along the sidearm, keeping the vitreous humor from becoming too acidic or too alkaline. Alternating between both configurations keeps the pH stable, as the internal electrodes cause a rise in pH while the sidearm electrode causes a drop in pH. In these experiments, two electrodes were put into the buffered saline itself and a third electrode into a glass sidearm filled with saline solution. To counter the problem of excessive baseline pH shift, a 2 mM solution of phosphate buffered saline (PBS) was used instead of pure saline. The solution was sparged at 25ml/minute and heated with a water bath to 37°C to simulate the fluid motion in the vitreous humor and temperature of the human body. A DC charge of 800 µA was applied to the electrodes to stimulate the production of oxygen and a change in pH. The internal electrodes were used in three minute increments until the pH had moved one pH unit above the baseline, then the sidearm electrode was used in 1.5 minute increments to bring the pH down 2 units. Afterward, the internal electrodes were used to bring the pH back to the baseline. However, the exact amount of time needed to reach the acceptable limits of high and low pH was variable, and on occasion use of the internal electrode after using the sidearm electrode for a long period of time caused the pH to drop for unknown reasons. The next step of this process would be to repeat the experiment with a solution that is more like the vitreous humor of the eye, and eventually move on to implanting the electrodes within an actual eye.

Electron Transfer in Molecular Wires. ELICIA SELVAGGIO (Dowling College, Oakdale, NY, 11767) JOHN MILLER (Brookhaven National Laboratory, Upton, NY, 11973)

Conjugated oligofluorenes with two to ten monomer units (F2 to F10) were used to address fundamental questions regarding eletron capture capacity and delocalization of charge. The oligofluorenes were reacted with sodium metal in tetrahydrofuran (THF) under vacuum, and ultraviolet/visible/near infrared (UV-vis-NIR) spectroscopy was used to measure the formation of anions, dianions, trianions, and tetranions. When reacted with sodium, F2 through F10 formed anions and dianions. Trianions and tetranions were observed in F4 and larger oligofluorenes. The absorption maxima, wavelengths at the maximum absorbances, and extinction coefficients were determined for each species formed. The study indicates that oligofluorenes can capture and store multiple electrons from sodium metal, and that the negatively-charged molecules are stable in the absence of air. Results for the series indicate that the length occupied by an electron is three to five monomer units. These results are consistent with the value obtained in polyfluorene by a different method in this lab. This challenges the notion that electrons are delocalized over the entire length of a conjugated molecule, and it has implications for understanding the fundamental nature of charged molecules in conjugated systems.

Electronic Characterization of Rare-Earth Doped Telluride Semiconductors. ANDREW OLSON and ERIK TOPP (Diablo Valley College, Pleasant Hill, CA, 94523) DALE L. PERRY (Lawrence Berkeley National Laboratory, Berkley, CA, 94720)

Zinc telluride and telluride-containing compounds have been extensively analyzed by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) in order to determine the chemical states and shifts in electronic energy levels of the elements present in the materials. To a lesser extent, chemical shifts of gadolinium lines in various compounds have also been studied. However, the characterization of ZnTe:Gd by XPS and AES is practically non-existent. Use of this material as a semiconductor in various applications requires that electrical contact be maintained between the material’s surface and other electrical components. Buildup of oxides and other species on the surface can cause insulating effects, hampering the material’s intended performance. It is, therefore, of interest to study surface reactions of the compound with air in order to identify surface product films that may adversely affect the utility of ZnTe:Gd as a multipurpose semiconductor. The current study was an initial characterization of these materials using XPS and AES. Observed spectra for the initial, "as received" surface yielded data consistent with the presence of Gd₂O₃, ZnO, and TeO₂. Spectral parameters including binding energies, spin-orbit splitting, satellite structure, and kinetic energy Auger lines of elements compared favorably to analogous features in spectra of other Zn-Te-Gd compounds. Surface charging of the material was observed and studied in conjunction with argon ion sputtering. The results indicated that insulating surface films do indeed form on these materials in air, films that can act as interfacial layers between the semiconductor material and other materials such as electrical contacts attached to the surface of the semiconductor. A future examination of this material by other characterizing methods and types of instrumentation will provide further insight into the chemistry, structure, and electronic properties of this material and shed more light on the formation of the surface layers under ambient air exposure.

Energetics of Electron Transfer and Charge Separation in Moderate to Low Polarity Solvents. BRIAN ALBERT (Columbia University, New York, NY, 10027) JOHN MILLER (Brookhaven National Laboratory, Upton, NY, 11973)

Because photosynthesis occurs in a region of low polarity so that photoelectrons store their absorbed energy in new chemical bonds instead of emitting it as heat through interaction with the solvent, studying electron transfer and charge separation in low polarity solvents will have applications in new solar energy storage. These experiments combine strong electron donors (metallocenes) and strong electron acceptors (quinones) to obtain ion formation by thermal equilibria in media of moderate to low polarity. In solvents of a range of dielectric constants, the extent to which cobaltocene and various quinones formed ion pairs and separated to form free ions was measured via conductivity and UV-Vis spectroscopy. Gibbs free energy changes were calculated for both the electron transfer and charge separation reactions in various solvents using acetonitrile as a standard highly polar solvent. With known values for the ionization potential of cobaltocene and the electron affinities of the quinones, Gibbs free energy changes observed in the moderately polar solvent, tetrahydrofuran (THF), were fit to the theoretical Born solvation energy and Coulomb potential models. Predictions made for free energy changes in solvents of very low dielectric constants disagreed with experimental data because a fourth species, charge transfer complex, becomes more significant in relative concentration, thus introducing a third equilibrium. Also, molecule structure of the solvent molecule was found to affect Gibbs free energy changes of ion formation. Approximations of neutral specie, ion pair, and free ion concentrations became more difficult in low polarity solvents because of charge transfer complexes that appear as broadened peaks in UV-Vis absorption spectra as well as extremely low conductivity measurements. Observed Gibbs free energy changes were found to be significantly more unfavorable compared to redox potentials of the same reactions determined electrochemically. The difference is attributed to the stabilization caused by salt in solution required for the electrochemical method.

Evaluation of relative metal nucleophilicities of diphenyldithiophosphinate ligands using gas-phase dissociation reactions. CHRISTOPHER LEAVITT (Wichita State University, Wichita, KS, 67260) ANITA GIANOTTO (Idaho National Laboratory, Idaho Falls, ID, 83415)

The relative metal cation nucleophilicities of a series of unique diphenyldithiophosphinate ligands were evaluated by forming [metal-mixed ligand]^- complexes, then fragmenting them using competitive collision induced dissociation. The bis(trifluoromethylphenyl)dithiophosphinate anions are of high interest because they have demonstrated potential for exceptional separation of Am³⁺ from lanthanide trications. With respect to sodium and europium (III), the unmodified diphenyldithiophosphinate anion (L_u^-) was compared with three different ligands, which varied in terms of the position of the trifluoromethyl (TFM) group on the phenyl rings: bis(ortho-TFM) (L₁^-), (ortho-TFM)(meta-TFM) (L₂^-), and bis(meta-TFM) (L₃^-). Relative to Na⁺, the unmodified L_u^- anion was the strongest nucleophile. Comparing the TFM derivatives, the bis(ortho-TFM) derivative, L₁^-, was found to be the strongest nucleophile, while the bis(meta-TFM), L₃^-, was the weakest, and the mixed ortho,meta derivative was intermediate. Similar experiments were performed using europium nitrate complexes; ionic dissociation of these complexes always produced the anionic TFM ligands, showing again that the unmodified L_u^- was the strongest nucleophile. The europium (III) nitrate complexes also underwent redox elimination of radical ligands. The tendency of the ligands to undergo oxidation and be eliminated as neutral radicals followed the same trend as the nucleophilicities for Na⁺, viz. L_u^- > L₁^- > L₂^- > L₃^-.

Fuel Cells: Synthesis and Characterization of Sulfonated Polysulfone for Proton Exchange Membrane (PEM). NANCY DAVENPORT (Chicago State University, Chicago, IL, 60628) DR. ASARE NKANSAH (Argonne National Laboratory, Argonne, IL, 60439)

Fuel cells are electrochemical energy conversion devices which convert hydrogen and oxygen into water in the process of generating electricity. The most common fuel cells are proton exchange membrane fuel cells (PEMFC). In order to develop newer proton exchange membrane (PEM) material, a monomer containing protogenic sulfonic acid groups on the pendant branches was prepared from commercially available 2,2’diallylbisphenol A via two different reactions. The course of the reaction was followed by thin layer chromatograms. This new monomer was then polymerized with 4, 4’-dichlorodiphenyl sulfone by step growth polymerization. The resulting polymer was characterized by NMR. The most striking feature of this new polysulfone was its extremely high decomposition temperature. Future work involves conductivity and viscosity measurements to determine the application of sulfonated polysulfone as (PEM) in fuel cells.

Increasing Activity for Oxygen Reduction of Cathode Electro-Catalysts in Fuel Cells. JOSE REGALBUTO (University of Illinois, Urbana, IL, 61801) D.J. LIU (Argonne National Laboratory, Argonne, IL, 60439)

As the search for alternatives to gasoline powered internal combustion engines intensifies, more attention is drawn to the use of fuel cells as an alternative power source. Fuel cells directly convert chemical to electrical energy, and are more efficient than internal combustion engines. The objective of our research is to identify and test new approaches in preparing electro-catalysts for use in fuel cells. We focused on two methods for the synthesis of cathode catalysts. The first was to steam activate a catalyst support before impregnating it with platinum. The second was to test a platinum free catalyst in basic media. A special emphasis was placed on using aligned carbon nanotubes as a catalyst support. Wet chemistry and gas phase vapor deposition methods were used to synthesize the catalysts. Our prepared catalysts were evaluated using standard electrochemical methods, with a focus on rotating disk electrode tests. We found that steam activation over a carbon nanotube support can improve oxygen reduction reaction (ORR) activity in acidic conditions. We also found that iron and nitrogen doped carbon nanotubes show good ORR activity in basic conditions. This work is part of a larger project to determine the feasibility of and make new catalysts for a direct ethanol fuel cell.

In-Situ Analysis of Platinum Degradation for Fuel Cell Catalysts using Small-Angle X-Ray Scattering. JAMES GILBERT (University of Illinois at Chicago, Chicago, IL, 60607) MATT SMITH (Argonne National Laboratory, Argonne, IL, 60439)

Catalyst durability during Polymer Electrolyte Fuel Cell (PEFC) operation remains a key challenge in developing a cost effective PEFC with an acceptable lifetime for both automotive and stationary power generation. Understanding the mechanisms of catalyst degradation is essential for furthering research toward lengthening fuel cell lifetimes. Platinum (Pt) and platinum-alloys are considered to be state-of-the-art catalysts for PEFCs. The precise method of the Pt corrosion is still unknown. However, several mechanisms have been proposed such as Pt dissolution and re-deposition (Ostwald ripening), coalescence of platinum particles via migration on the carbon support, and Pt particle agglomeration triggered by corrosion of the carbon support. Novel synthesis of nano-sized catalyst particles has improved power performance and lowered material cost. However, it is observed that the smaller the particles the faster the degradation and agglomeration via, nominally, the above mechanisms. Small Angle X-Ray Scattering (SAXS) is a powerfully accurate x-ray technique for characterizing particle size, especially between 1 and 100 nm. Thus SAXS is highly specific to the nano-sized Pt catalysts, which have been observed to aggregate to as much as 30 nm from an initial size of approximately 2-3 nm. In this study, samples of 20 wt% (2.2 nm) and 40 wt% (2.8 nm) Pt supported on commercial Vulcan XC-72 carbon were characterized in-situ using SAXS while cycling the potential between 0.4 and 1.4 V for up to 16 hours in an electrochemical half-cell. Particle size change was observed to increase 55% and 50% for the 20 wt% and 40 wt% Pt/C catalysts, respectively. SAXS data shows trends in particle growth correlated to cycle time and electrochemical potential. The results contained in this study have significant implications with regards to the durability of carbon-supported Pt-based nano-sized catalysts. These results also make a significant contribution to the larger effort in determining the mechanism by which Pt degrades.

Inkjet Printing of Nickel and Silver Metal Solar Cell Contacts. ROBERT PASQUARELLI (Rochester Institute of Technology, Rochester, NY, 14623) CALVIN CURTIS (National Renewable Energy Laboratory, Golden, CO, 89401)

With about 125,000 terawatts of solar power striking the earth at any given moment, solar energy may be the only renewable energy resource with enough capacity to meet a major portion of our future energy needs. Thin-film technologies and solution deposition processes seek to reduce manufacturing costs in order to compete with conventionally coal-based electricity. Inkjet printing, as a derivative of the direct-write process, offers the potential for low-cost, materials-efficient deposition of the metals for photovoltaic contacts. Advances in contact metallizations are important because they can be employed on existing silicon technology and in future-generation devices. We report on the atmospheric, non-contact deposition of nickel (Ni) and silver (Ag) metal front contacts from metal-precursor organic inks on a Dimatix inkjet printer at 180-220°C. Near-bulk conductivity Ag contacts were successfully printed up to 4.5 µm thick and less than 125 µm wide on the silicon nitride antireflective coating of silicon solar cells. Thin, high-resolution Ni adhesion-layer lines were printed on glass and zinc oxide at 55 nm thick and 80 µm wide with a conductivity two orders magnitude less than bulk. Additionally, the ability to print multi-layered metallizations (Ag on Ni) on transparent conducting oxides was demonstrated and is promising for contacts in copper-indium-diselenide (CIS) solar cells. Future work will focus on further improving resolution, printing full contacts on devices, and investigating copper inks as a low-cost replacement for Ag contacts.

Integrated Electrodialysis Membrane Process for Beneficial Use of Coalbed Methane Produced Water. STEPHANIE LE CLAIR (Saint Mary's College of California, Moraga, CA, 94575) PAULA MOON (Argonne National Laboratory, Argonne, IL, 60439)

During oil and gas production, the water that is trapped in underground formations is brought to the surface. About 15-20 billion bbl of this water, known as produced water, is generated in the United States each year. The Colorado Energy Research Institute at the Colorado School of Mines has brought together a team of scientists and engineers to address produced water management. In support of this effort, Gas Technology Institute and Argonne National Laboratory have been collaborating in using electrodialysis (ED) to remove ions from water in the Powder River Basin (PRB) so that the water may be used for irrigation or livestock drinking water. In most states, the criteria needed for beneficial use include averages of total dissolved solids of 1,000-2,000 mg/L, a pH range of 6-8, and a sodium absorption ratio (SAR) of less than 6. In order to meet water discharge specifications, experiments were conducted with produced water from the PRB area to determine the parameters needed for the ED system. The electrodialysis membrane type, current density, stock concentrations, and power consumption were tested to find an optimum for each variable. Different post-demineralization treatments were also performed, using calcium carbonate, calcium sulfate and limestone, to determine which was the most effective at desalting the water, after the use of the ED system. Results showed that the best configuration for the ED system consisted of using of a non-selective membrane as the cation membrane, a sodium bicarbonate solution as the concentrate and a current density of 4.00 mAmps/cm². This setup provided the most cost-effective ED system, yielding 88.9% desalination with a modest energy input of 0.18 kWh/lb of NaCl removed. For post-treatment demineralization, limestone proved to be the most cost-effective way to lower the SAR value to below 6. These experiments showed that it should be possible to desalt the produced water up to around 80% and then treat the water with limestone to reach the water quality needed to dispose of it for beneficial use. A long term membrane stability experiment is currently underway.

Investigating the microwave-assisted synthesis of ionic liquids. KIJANA KERR (Queensborough Community College, Bayside, NY, 11364) JAMES F. WISHART (Brookhaven National Laboratory, Upton, NY, 11973)

Ionic liquids (ILs), which have gained a lot of attention as alternative solvents recently and have found industrial applications, are salts that are liquid at or near room temperature. This makes them good solvents for a range of organic and polymeric compounds. ILs typically consist of large nitrogen-containing organic cations and small inorganic anions. The need is increasing for developing synthetic procedures that are faster, more efficient, and more economical as the number of applications for ionic liquids increase. Typical advantages of microwave-assisted syntheses are to significantly reduce reaction times and increase the product yield. The microwave assisted syntheses of halide salts based on DABCO diazabicyclo[2.2.2]octane and their conversion into ionic liquids are reported here. Reaction conditions, such as the temperature, the nature of the reaction solvent and the length of reaction time, have been varied. A comparison of these two synthetic techniques (thermal and microwave-assisted) and the physical characterization of these compounds are reported. Preliminary results show that quaternization has been achieved to produce mono- and di- substituted DABCO halide salts with different substituent groups such alkyl, ethoxy and hydroxyl. Conditions have been worked out to obtain some of these salts in high yields, particularly alkyl containing DABCO salts. Structure determination of the resulting ionic liquids was done using 1H, 13C and 31P NMR spectroscopy. Subsequent characterization, including differential scanning calorimetry (DSC), of a series of compounds is reported. Dramatic differences in melting points were observed with anion variation of DABCO compounds.

Isolation and Analysis of Above Cloud Point Precipitates in Palm and Poultry Fat Derived Biodiesels. REBECCA CALLAHAN (Hendrix College, Conway, AR, 72032) TERESA ALLEMAN (National Renewable Energy Laboratory, Golden, CO, 89401)

As the search for alternatives to petroleum based fuels continues many promising options have arisen. Vegetable and animal fat derived biodiesels have become one viable alternative to petroleum based diesel fuel. Biodiesel can be directly substituted for petrodiesel while exhibiting less hazardous and superior environmental properties, such as its high flash point and biodegradability. Biodiesel typically has high cloud and pour points than conventional diesel. Additionally, a small fraction of biodiesels also show a precipitate formed above the cloud point. This precipitate may accumulate in storage tanks or on fuel filters inhibiting biodiesel’s distribution. The identification of this precipitate may assist in finding a solution to its operability problems or an identification method of the fuels it impairs, thus enhancing the capability of biodiesel as an alternative fuel. Multiple samples of biodiesel were visually examined for the presence of precipitate at room temperature and two samples of different feed stocks were chosen for precipitate analysis, one palm and one poultry fat. Three steps were implemented to identify their precipitates. First, the mass of precipitate was increased by chilling biodiesel above its cloud point. The precipitate was then isolated from biodiesel through filtration and solvent washing. Lastly it was identified using the following analytical techniques: Fourier Transform Infrared Spectroscopy (FT-IR), Gas Chromatography Flame Ionization Detector (GC-FID) pyrolysis Molecular Beam Mass Spectrometry (py-MBMS), and proton, carbon 13 and Distortionless Enhancement by Polarization Transfer Nuclear Magnetic Resonance (H NMR and 13C NMR and DEPT NMR.) Using these methods of analysis it was determined that the two samples differed in physical appearance, yet both contained a large quantity of monoglycerides. Approximately ten percent of the samples examined in this work showed precipitation upon cooling, additional examination of biodiesels needs to be conducted to verify that this precipitation is universal to all feed stocks. Additionally, after the definitive identification of the precipitates, their impact on fuel filters must be quantified from the distributor to the vehicle.

Kinetic Studies of Ammonia Borane. STEPHEN BERDS (Monroe Community College, Rochester, NY, 14623) WENDY SHAW (Pacific Northwest National Laboratory, Richland, WA, 99352)

Chemistry Abstracts: