Susan D. Radzinski

Bio: Susan D. Radzinski is an academic researcher from Los Alamos National Laboratory. The author has contributed to research in topics: Proton exchange membrane fuel cell & Water vapor. The author has an hindex of 6, co-authored 7 publications receiving 1397 citations.

Water Uptake by and Transport Through Nafion® 117 Membranes

Abstract: Water uptake and transport properties of Nafion[reg sign] 117 membranes at 30 C are reported here. Specifically, the authors have determined the amount of water taken up by membranes immersed in liquid water and by membranes exposed to water vapor of variable water activity. Transport parameters measured are the diffusion coefficient and relaxation time of water in the membrane and the protonic conductivity of the membrane as functions of membrane water content. The ratio of water molecules carried across the membrane per proton transported, the electro-osmotic drag coefficient, also was determined for a limited number of membrane water contents. The drag coefficient is contrasted with the experimentally determined net water transport across an operating PEM fuel cell.

Sorption behavior of pertechnetate ion on reillextm-hpq anion exchange resin from hanford and melton valley tank waste simulants and sodium hydroxide/sodium nitrate solutions

Abstract: The batch distribution coefficients (Kd, mL solution /g dry resin) for pertechnetate (TcO4) between ReillexTMHPQ anion exchange resin and various caustic solutions have been determined. The average Kd value in 1.5 M NaNO3/l.0 M NaOH solution is (262.2 ± 12.6) mL7sol;g for TcO4 − ranging from 1.0 × 10TM M to 5.0 × 10−4 M. Pertechnetate Kd values were measured in a series of NaOH7sol;NaNO3 solutions. The series are: 1.00 M NaOH with 0.010 to 5.00 M NaNO3; 0.100 M NaOH with 0,010 to 5.00 M NaNO3; 0.100 MNaNO3 with 0.10 to 5.00M NaOH; 1.00MNaNO3 with 0.10 to 5.00 M NaOH; 1.50 M NaNO3 with 0.10 to 5.00 M NaOH; 3.50 M NaNO3 With 0.10 to 5.00 M NaOH. The Kd values are described by the following equation. This equation was used to predict the Kd values for a series of tank waste simulants. The predicted Kd values are different from the measured values with an average absolute difference of (29 ± 10)%. Pertechnetate kdvalues for 101-SY, 103-SY, DSS, DSSF-2.33, DSSF-5, DSSF7, 101-AW, and Melton Valley simu...

Feed Adjustment Chemistry for Hanford 101-SY and 103-SY Tank Waste: Attempts to Oxidize the Non-Pertechnetate Species

Abstract: More than 50% of the technetium in Hanford 101-SY and 103-SY tank waste is not pertechnetate (TcO4−). These non-pertechnetate species (TcN) are stable, soluble, reduced complexes of technetium. In order to remediate these waste, it will be necessary to oxidize these species to TcO4−. For radioanalytical purposes, oxidation requires digestion in Ce(IV)/16M HNO3. Many oxidants are ineffective. Sodium peroxydisulfate, sodium peroxydisulfate/silver(I), and ozone oxidize all of the technetium species to pertechnetate.

Reillex™-hpq anion exchange column chromatography: removal of pertechnetate from dssf-5 simulant at various flow rates

Abstract: The 1% breakthrough volumes (BTV) for TcO{sub 4}{sup {minus}} on Reillex-HPQ anion exchange resin columns have been measured as a function of flow rate. The 1% BTV is defined as that point in the column loading when an aliquot of eluent contains 1% of the activity of an equivalent aliquot of column feed solution. The 2.54 x 50 cm resin columns were loaded with a DSSF-5 [Hanford Waste] simulant containing 5.0 x 10{sup {minus}5} M {sup 99}TcO{sub 4}{sup {minus}} and {sup 95m}TcO{sub 4}{sup {minus}} tracer. Seven flow rate experiments were performed with flow rates varying from 15 to 65 mL/min. The columns were up-flow eluted with a 1.0 M NaOH/1.0 M ethylenediamine/0.0050 M SnCl{sub 2} solution. For six flow experiments, the average technetium eluted was (97.1 {+-} 6.0) percent and the average technetium accountability for loading and eluting was (97.8 {+-} 5.9) percent. Loading experiments to 90% breakthrough were performed at a flow rate of 60 mL/min for Reillex-HPQ and AG{reg_sign}MP-1 columns. The Reillex-HPQ displayed better column loading performance as indicated by smaller percent breakthrough volumes. However, in this experiment, the AG MP-1 gave 100% elution, whereas the Reillex-HPQ gave only 70% elution.

Technetium Oxidation State Adjustment for Hanford Waste Processing

Abstract: Technetium, as the pertechnetate anion (TcO4 −), is a very mobile species in the environment.1 This characteristic, along with its long half-life, (99Tc, t1/2 = 213,000 a) makes technetium a major contributor to the long-term hazard associated with the storage of low level waste (LLW) forms.2 Thus, technetium partitioning from nuclear waste stored at DOE sites (Hanford, Savannah River, Melton Valley, etc.) may be required so that the LLW forms meet the DOE performance assessment criteria for storage.

State of Understanding of Nafion

Abstract: Equivalent weight (EW) is the number of grams of dry Nafion per mole of sulfonic acid groups when the material is in the acid form. This is an average EW in the sense that the comonomer sequence distribution (that is usually unknown to the investigator and largely unreported) gives a distribution in m in this formula. EW can be ascertained by acid-base titration, by analysis of atomic sulfur, and by FT-IR spectroscopy. The relationship between EW and m is EW ) 100m + 446 so that, for example, the side chains are separated by around 14 CF2 units in a membrane of 1100 EW. Common at the time of this writing are Nafion 117 films. The designation “117” refers to a film having 1100 EW and a nominal thickness of 0.007 in., although 115 and 112 films have also been available. Early-reported studies involved 1200 EW samples as well as special experimental varieties, some being rather thin. The equivalent weight is related to the property more often seen in the field of conventional ion exchange resins, namely the ion exchange capacity (IEC), by the equation IEC ) 1000/EW. The mention of the molecular weight of high equivalent weight (EW > 1000 g‚mol-1) Nafion is almost absent in the literature, although the range 105-106 Da has been mentioned. As this polymer does not form true solutions, the common methods of light scattering and gel permeation chromatography cannot be used to determine molecular weight as well as the size and shape of isolated, truly dissolved molecules. Studies of the structure of this polymer in solvent (albeit not a true solution) will be mentioned in the scattering section of this review. It should be noted that Curtin et al. performed size exclusion chromatography determinations of the molecular weight distribution in Nafion aqueous dispersions after they were heated to high temperatures (230, 250, and 270 °C).1 Before heating, there was a high molecular weight shoulder on a bimodal distribution, due to molecular aggregates, but this shoulder disappeared upon heating, which indicated that the aggregates were disrupted. The peaks for the monomodal distribution for the heated samples were all located at molecular weights slightly higher than 105 g‚mol-1. Also, light scattering experiments revealed that the radius of gyration had a linear dependence on the molar mass of the aggregates, which suggests that the particles are in the form of rods or ribbons, or at least some elongated structure. Nafion ionomers are usually derived from the thermoplastic -SO2F precursor form that can be extruded into sheets of required thickness. Strong interactions between the ionic groups are an obstacle to melt processing. This precursor does not possess the clustered morphology that will be of great concern in this article but does possess Teflon-like crystallinity which persists when the sulfonyl fluoride form is converted to, for example, the K+ form by reacting it with KOH in water and DMSO. Thereafter, the -SO3H form is achieved by soaking the film in a sufficiently concentrated aqueous acid solution. Extrusion of the sulfonyl fluoride precursor can cause microstructural orientation in the machine direction, * Address correspondence to either author. Phone: 601-266-5595/ 4480. Fax: 601-266-5635. E-mail: Kenneth.Mauritz@usm.edu; RBMoore@usm.edu. 4535 Chem. Rev. 2004, 104, 4535−4585

Scientific aspects of polymer electrolyte fuel cell durability and degradation.

Abstract: Rod Borup is a Team Leader in the fuel cell program at Los Alamos National Lab in Los Alamos, New Mexico. He received his B.S.E. in Chemical Engineering from the University of Iowa in 1988 and his Ph.D. from the University of Washington in 1993. He has worked on fuel cell technology since 1994, working in the areas of hydrogen production and PEM fuel cell stack components. He has been awarded 12 U.S. patents, authored over 40 papers related to fuel cell technology, and presented over 50 oral papers at national meetings. His current main research area is related to water transport in PEM fuel cells and PEM fuel cell durability. Recently, he was awarded the 2005 DOE Hydrogen Program R&D Award for the most significant R&D contribution of the year for his team's work in fuel cell durability and was the Principal Investigator for the 2004 Fuel Cell Seminar (San Antonio, TX, USA) Best Poster Award. Jeremy Meyers is an Assistant Professor of materials science and engineering and mechanical engineering at the University of Texas at Austin, where his research focuses on the development of electrochemical energy systems and materials. Prior to joining the faculty at Texas, Jeremy workedmore » as manager of the advanced transportation technology group at UTC Power, where he was responsible for developing new system designs and components for automotive PEM fuel cell power plants. While at UTC Power, Jeremy led several customer development projects and a DOE-sponsored investigation into novel catalysts and membranes for PEM fuel cells. Jeremy has coauthored several papers on key mechanisms of fuel cell degradation and is a co-inventor of several patents. In 2006, Jeremy and several colleagues received the George Mead Medal, UTC's highest award for engineering achievement, and he served as the co-chair of the Gordon Research Conference on fuel cells. Jeremy received his Ph.D. in Chemical Engineering from the University of California at Berkeley and holds a Bachelor's Degree in Chemical Engineering from Stanford University. Bryan Pivovar received his B.S. in Chemical Engineering from the University of Wisconsin in 1994. He completed his Ph.D. in Chemical Engineering at the University of Minnesota in 2000 under the direction of Profs. Ed Cussler and Bill Smyrl, studying transport properties in fuel cell electrolytes. He continued working in the area of polymer electrolyte fuel cells at Los Alamos National Laboratory as a post-doc (2000-2001), as a technical staff member (2001-2005), and in his current position as a team leader (2005-present). In this time, Bryan's research has expanded to include further aspects of fuel cell operation, including electrodes, subfreezing effects, alternative polymers, hydroxide conductors, fuel cell interfaces, impurities, water transport, and high-temperature membranes. Bryan has served at various levels in national and international conferences and workshops, including organizing a DOE sponsored workshop on freezing effects in fuel cells and an ARO sponsored workshop on alkaline membrane fuel cells, and he was co-chair of the 2007 Gordon Research Conference on Fuel Cells. Minoru Inaba is a Professor at the Department of Molecular Science and Technology, Faculty of Engineering, Doshisha University, Japan. He received his B.Sc. from the Faculty of Engineering, Kyoto University, in 1984 and his M.Sc. in 1986 and his Dr. Eng. in 1995 from the Graduate School of Engineering, Kyoto University. He has worked on electrochemical energy conversion systems including fuel cells and lithium-ion batteries at Kyoto University (1992-2002) and at Doshisha University (2002-present). His primary research interest is the durability of polymer electrolyte fuel cells (PEFCs), in particular, membrane degradation, and he has been involved in NEDO R&D research projects on PEFC durability since 2001. He has authored over 140 technical papers and 30 review articles. Kenichiro Ota is a Professor of the Chemical Energy Laboratory at the Graduate School of Engineering, Yokohama National University, Japan. He received his B.S.E. in Applied Chemistry from the University of Tokyo in 1968 and his Ph.D. from the University of Tokyo in 1973. He has worked on hydrogen energy and fuel cells since 1974, working on materials science for fuel cells and water electrolysis. He has published more than 150 original papers, 70 review papers, and 50 scientific books. He is now the president of the Hydrogen Energy Systems Society of Japan, the chairman of the Fuel Cell Research Group of the Electrochemical Society of Japan, and the chairman of the National Committee for the Standardization of the Stationary Fuel Cells. ABSTRACT TRUNCATED« less

Proton Conductivity: Materials and Applications

Abstract: In this review the phenomenon of proton conductivity in materials and the elements of proton conduction mechanismsproton transfer, structural reorganization and diffusional motion of extended moietiesare discussed with special emphasis on proton chemistry. This is characterized by a strong proton localization within the valence electron density of electronegative species (e.g., oxygen, nitrogen) and self-localization effects due to solvent interactions which allows for significant proton diffusivities only when assisted by the dynamics of the proton environment in Grotthuss and vehicle type mechanisms. In systems with high proton density, proton/proton interactions lead to proton ordering below first-order phase transition rather than to coherent proton transfers along extended hydrogen-bond chains as is frequently suggested in textbooks of physical chemistry. There is no indication for significant proton tunneling in fast proton conduction phenomena for which almost barrierless proton transfer is suggest...

Transport in proton conductors for fuel-cell applications: simulations, elementary reactions, and phenomenology.

Abstract: 1. Introduction 46372. Theoretical Methodologies and Simulation Tools 46402.1. Ab Initio Quantum Chemistry 46412.2. Molecular Dynamics 46422.2.1. Classical Molecular Dynamics and MonteCarlo Simulations46432.2.2. Empirical Valence Bond Models 46442.2.3. Ab Initio Molecular Dynamics (AIMD) 46452.3. Poisson−Boltzmann Theory 46452.4. Nonequilibrium Statistical Mechanical IonTransport Modeling46462.5. Dielectric Saturation 46473. Transport Mechanisms 46483.1. Proton Conduction Mechanisms 46483.1.1. Homogeneous Media 46483.1.2. Heterogeneous Systems (ConfinementEffects)46553.2. Mechanisms of Parasitic Transport 46613.2.1. Solvated Acidic Polymers 46613.2.2. Oxides 46654. Phenomenology of Transport inProton-Conducting Materials for Fuel-CellApplications46664.1. Hydrated Acidic Polymers 46664.2. PBI−H