Chemistry Commons^™

An Investigation Of Inhibition Mechanism Of Cerium For Aluminum Alloy 2024-T3, Min-Hua Shao, Yan Fu, Rong-Gang Hu, Chang-Jian Lin

Journal of Electrochemistry

Cerium compounds are promising inhibitors for aluminum alloy. However, the inhibition mechanism is not very clear. Scanning microreference electrode (SMRE) technique was used to probe the potential imaging of Al 2024 T3 in NaCl and CeCl₃ solution. The results of SMRE showed that in NaCl solution a severe localized corrosion occurred on the surface of Al 2024 specimen at once and maintained for a long time. The corrosion activity of Al alloy in CeCl₃ decreased with immersion time and disappeared finally. Additionally, the competition of inhibition and aggression between Ce³⁺ and Cl^- on Al alloy was …

Electrochemical Behaviors Of Vanadium(V) Compounds In H2So4 Solution, Yang Liu, Hong-Tao Liu, Xi Xia

Journal of Electrochemistry

The electrochemical behaviors of vanadium(V) compounds(NH₄VO₃ and V₂O₅) in H₂SO₄ solutions were investigated by cyclic voltammetry (CV) and rotation ring disk electrode (RRDE) techniques. There were three anodic peaks and three cathodic peaks appeared on the CV plots at inert Pt electrode. But compared with the V₂O₅, the CV plot of NH₄VO₃ had one more anodic peak. There also appeared four anodic peaks at RRDE plots. We carefully analyzed these peaks and made some reasonable initial explaination.

Electrosynthesis Of Glyoxylic Acid In A Packed Bed Reactor, Jin-Hong Fan, Jun Li, Yu-Zhong Su, Hao-Qi Gao

Journal of Electrochemistry

Glyoxylic acid was produced by electroreduction of oxalic acid in a packed bed reator. The cathodic and anodic electrolytes were super-saturated oxalic and hydrochloric acid aqueous solutions separated by a super-acid ion-exchange membrane. The current efficiency and yield of glyoxylic acid were studied under different structured packed bed reactors and different electrode materials, temperatures and current densities. The results indicated that the current efficiency of synthsis of glyoxylic acid was over 66.2% and the concentration of glyoxylic acid could reach 2.02% after 45min electrolysis with cathode of lead particles and anode of graphite board under conditions of temperature 32 ℃, …

Effect Of The Brightener On The Behavior Of The Silver Electrodeposition, Jin Hu, Hui-Min Wu, Xiang-Ming Feng, Wei-Dong Li, Zheng-Zhong Zuo, Yun-Hong Zhou

Journal of Electrochemistry

The effect of the brightener on the behavior of the silver electrodeposition in cyanide solution was studied by potentiostatically step and rotating dise electrode (RDE) as well as X-ray diffraction (XRD) and scanning electron microscope (SEM). It was found that the silver electrodeposition was not changed by the addition of the brightener to the fundarmental solution. But it apparently increased the solution's micro-leveling effection and remarkably improved the coating's surface lightness. The coating's orientation isn't changed by the addition of the brightener in the light of the XRD result. The effectivness of the brightener was also discussed by the half-wideth …

Determination Of Copper In The Waste Water Of Plating By Chronocoulometry For Flowing Solution, Xin-Hua Lin, Wei Chen

Journal of Electrochemistry

The chronocoulometry for flowing solution was devoloped and applied to the detemination of copper(Ⅱ) in the waste water of plating. The linear range of copper(Ⅱ) was 2～16mg/L, and the relative standard deviation was less than 0.1% (n =8). The recovery was 98%～103% for copper(Ⅱ) in the waste water.Chronocoulometry for flowing solution overcomed noise disturbance resulting from capacity current and variety of property of electrode surface. This method was sensitive,accurate and well reproducible.

Some Trends Of Electrochemistry In 21st Century, Zhong-Hua Lin

Journal of Electrochemistry

The important advances in electrochemistry in the late twentieth century are reviewed and some trends of electrochemistry in earlier stage of the twenty-first century are discussed. Future researches in electrochemistry are indicated with an emphasis being made on the electrochemistry in new systems.

Further Evidence For Surface Properties Of Porous Silicon Resulting In Electroluminescence, Zhan-Jun Zhang, Bin Wu, Jing-Jian Li, Zhong-Fan Liu, Sheng-Min Cai

Journal of Electrochemistry

The electroluminescence of porous silicon in solutions at positive biases was investigated by luminescence spectrometer. The electroluminescence of porous silicon in solutions mainly depended on its surface properties. The elelctroluminescence was much enhanced when the sample of porous silicon was electrolyzed once again which had undergone an electroluminescence test. The tests of both cyclic voltammetry and the luminescence of the sample of porous silicon prepared by repeated electrolysis provided further evidence that the electroluminescence of porous silicon in solutions at positive biases stemmed from the oxidation of Si-H on the surface of porous silicon. The voltage tunable emitting for porous …

Study On The Viscosity Of Lbg/Acetone Solution Mixed With Different Silica, Sheng-Liang Zhao, Guang-Ming Zhu, Cui-Ying Wang, Jin-Kua You, Zu-Geng Lin

Journal of Electrochemistry

LBG is a copolymer of vinylidene fluoride (VF2) and hexafluorpropylene (HFP), factors that influence the viscosity of the LBG solution such as the shear rate, plasticizer, the content of the fumed silica with different surface treatment are discussed in detail.

Photoelectrochemistry Of La3+ Doped Semiconductor Porous Films Sensitized By Ru(Bpy)2(Ncs)2 Dye, Li Zhang, Yan-Jie Ren, Sheng-Min Cai

Journal of Electrochemistry

The La³⁺-doped TiO₂ nanoparticles were prepared with hydrothermal method.The photoelectrochemical properties of La³⁺-doped TiO₂ nanoporous-film electrode sensitized by Ru(bpy)₂(NCS)₂ were studied. The conversion efficiency of light to electricity and the energy conversion efficiencies were ineased with the depth of La³⁺-doped TiO₂ nanoporous-film electrode.

Raman Spectroscopic Study On Mechanism Of Aluminum Triphosphate Pigment, Zhi-Jun Gu, Yong-Gui Liao, Zhi-Gang Zhang, Qi-Long Guo, Fang-Teng Su

Journal of Electrochemistry

The painted steel sample whose coating contained anticorrosive pigment has been investigated by Raman spectroscopy. The protective mechanism of aluminum triphosphate pigment for A3 steel is proposed as follows: Aluminum triphosphate can be dissolved and arrive at the surface of the steel.The dissolved triphosphate ions can complex with ferric ions.And the new products, namely ferric triphosphate, can strongly adhere at the surface of the steel by chemical bonds slowly. At last, a compact protective film, which effectively separates the steel substrate from the aggressive media, is formed at the steel surface.

Uncertainty In Determination Of Hydrogen Diffusion Coefficient In Metal Hydride Electrode Based On The Transition Region Of Diffusion-Controlled Impedance, Xian-Xia Yuan, Nai-Xin Xu

Journal of Electrochemistry

Hydrogen diffusion coefficient in MlNi_3.75Co_0.65 Mn_0.4Al_0.2 metal hydride electrode has been determined with transition region of diffusion-controlled impedance. Multiple solutions were obtained at each data point because of the periodic characteristic of some functions used in the calculation, and the maximum difference between the solutions reached several orders of magnitude. On the other hand, the solutions varied for different data points in the transition region of diffusion-controlled impedance of the same experimental plot. It could be concluded that this method is not so well defined and some modification is required.

Study On The Orthogonal Test Of Al-Substituted α-Ni(Oh)2 Prepared By Complexation-Precipitation Method, Hui Chen, Jian-Ming Wang, Tao Pan, Hui-Ming Xiao, Jian-Qing Zhang

Journal of Electrochemistry

Al-substituted α-Ni(OH)₂ was prepared by a complexation-precipitation method and characterized by XRD.The electrochemical performance was tested by the charge-discharge method. The experimental results of orthogonal test showed that the effect order of some key preparative conditions on the electrochemical performance of Al-substituted α-Ni(OH)₂ was the concentration of aqueous ammonia, the content of aluminum and pH value.The optimum prepareative conditions for obtaining the sample with maximum specific discharge capacity (304 mAh·g^-1) were 0.5 mol·L^-1 aqueous ammonia, 15 mol% Al content and pH 11.0.

Varying Current Electro-Synthesis Of Glyoxalic Acid In Pairs In The Fixed-Bed Electrolytic Cell, Yin-Sheng Chen, Xin-Sheng Zhang, Ying-Chun Dai, Wei-Kang Yuan

Journal of Electrochemistry

As for the process of the electro oxidation of glyoxal to glyoxalic acid, the electrolytic result of either fixed bed electrolytic cell or varying current electrolysis was better than that of either flat plate electrolytic cell or constant current electrolysis. The average current density of varying current electro synthesis of glyoxalic acid in pairs was 1535 A/m² and the current efficiency were 85.3% and 86.7% and the selectivity were 93.9% and 94.0% for the anodic oxidation and cathodal reduction respectively. The initial composition of anodic electrolyte was 7% glyoxal and 8% hydrochloric acid (W/W) and the cathodal electrolyte consisted …

The Determination Of The Best Modified Way And Microscopical Analysis For Enzyme/Immunoelectrodes, Sa-Ying Dong, Hong-Ren Wang, Yu-Zhu Gao, Guang-Zhang Chen, Ming-Xiang Lv, Bo-Yi Tian

Journal of Electrochemistry

In this paper, the electrochemical response characteristics of enzyme and immuno electrodes were studied by cyclic voltammetry under different conditions. Our goals were to determine the best modified way of bioelectrode, which was the base of biosensor's application. 30U GOD and 0.8 mg/mL SEC1 antibody were suitable to bioelectrode preparation and detection. The microscopical analysis was finished with scan microscopy.

Electrochemical Synthesis And Characterization Of The Nickel Electropolyurushiol Coordination Polymer, Feng Gao, Guo-Cai Shen, Jie-Yuan Tang, Wen-Gong Zhang

Journal of Electrochemistry

The nickel electropolyurushiol coordination polymer (EPU Ni²⁺) was obtained by the reaction between nickel chloride isopropyl alcohol solution with electropolyurushiol (EPU). The electrochemical polymerization of urushiol and the preparation of nickel electropolyurushiol coordination polymer were investigated. The coordination polymer was characterized by XPS, FT-IR, DMTA and AES methods, and its composition and structure were determined.The content of Ni²⁺ reached up to 7.5%. It was shown that there was certain coordination between Ni²⁺ and electropolyurushiol in the coordination polymer, thus cross-inks were formed. Therefore the glass transition temperature of the coordination polymer increased and heat resistance was …

Preliminary Study On Direct Ethanol Fuel Cell, Shu-Qin Song, Li-Kang Chen, Jian-Guo Liu, Zhao-Bin Wei, Qin Xin

Journal of Electrochemistry

The performance of a direct ethanol fuel cell based on Nafion115 was reported.PtRu/C and Pt/C were used as ethanol anode and oxygen cathode catalysts in a single cell of size 9 cm² .The effects of temperature, oxygen pressure, the flow rate of ethanol, and oxygen, and ethanol concentration were tentatively studied. The experimental results showed that the cell open circuit voltage 0.608 V, the cell voltage 0.329 V at 50 mA/cm², and the peak power density 19.25 mW/cm² were reached under the conditions of T_cell =85 ℃, P_O2 =0.5 MPa, C_ethanol =1.0 mol/L …

Nafion/Ptfe Composite Membrane For Pemfc, Fu-Qiang Liu, Dan-Min Xing, Jing-Rong Yu, Bao-Lian Yi, Hua-Min Zhang

Journal of Electrochemistry

In this work, Nafion/PTFE composite membrane was obtained by impregnating Nafion resin into the porous PTFE substrate membrane. For the obtained composite membrane, the Nafion content is about 50%. Mechanical properties such as the tensile strengths of dry and wet composite membranes and shrinkage upon dehydration were improved compared with Nafion membranes.The fuel cell performance of the 25 μm thick composite membrane was superior to that of Nafion 117 membrane.The oxygen permeability and water content of the composite membranes were also measured and compared with Nafion membranes.

C-Cl Bond Fission, Hcl Elimination, And Secondary Radical Decomposition In The 193 Nm Photodissociation Of Allyl Chloride, M. L. Morton, L. J. Butler, Thomas Alex Stephenson, F. Qi

Chemistry & Biochemistry Faculty Works

The primary photodissociation dynamics of allyl chloride upon excitation at 193 nm is investigated in a crossed laser-molecular beam scattering apparatus. Tunable vacuum ultraviolet (VUV) photoionization of the products provides a unique ability to learn about the secondary reaction products of the nascent photoproducts formed. The data show evidence for four significant primary reaction channels: a previously unidentified low kinetic energy C-Cl bond fission channel producing unstable allyl radicals, an excited state C-Cl bond fission channel producing Cl atoms with high translational energy, an HCl elimination pathway releasing significant energy to product translation to HCl and its momentum-matched mass 40 …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics: Quarterly Progress Report 11/16/01- 2/15/02, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the AAA proposed application.

Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with very limited density. The transport of oxygen and corrosion products, their interaction and variation of corrosion/precipitation along the flow are not well understood.

The first subtask of this project involves using a …

Development Of A Systems Engineering Model Of The Chemical Separations Process: Quarterly Progress Report 11/16/01- 2/15/02, Yitung Chen, Randy Clarksean, Darrell Pepper

Separations Campaign (TRP)

The AAA program is developing technology for the transmutation of nuclear waste to address many of the long-term disposal issues. An integral part of this program is the proposed chemical separations scheme.

Two activities are proposed in this Phase I task: the development of systems engineering model and the refinement of the Argonne code AMUSE (Argonne Model for Universal Solvent Extraction). The detailed systems engineering model is the start of an integrated approach to the analysis of the materials separations associated with the AAA Program. A second portion of the project is to streamline and improve an integral part of …

Hydrogen-Induced Embrittlement Of Candidate Target Materials For Applications In Spallation-Neutron-Target Systems, Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The purpose of this project is to evaluate the effect of hydrogen on cracking of candidate target materials for applications in spallation-neutron-target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The test materials will undergo appropriate thermal treatments prior to being hydrogen-charged by potentiostatic cathodic polarization technique in a simulated aqueous environment at different temperatures of interest. The specimens, upon completion of testing, will be metallographically examined. Further, the scanning electron microscopy (SEM) will be used to determine the extent and nature of cracking in the specimens tested. The thrust of the proposed …

The Influence Of Gold Substrate Topography On The Voltammetry Of Cytochrome C Adsorbed On Carboxylic Acid Terminated Self-Assembled Monolayers, Michael C. Leopold, Edmond F. Bowden

Chemistry Faculty Publications

Interfacial investigations of a protein monolayer electrochemical system, equine cytochrome c (cyt c) adsorbed to carboxylic acid terminated self-assembled monolayer (COOH SAM) modified gold electrodes, were performed. Electrochemical, spectroscopic, and scanning probe microscopy techniques were utilized to explore the influence of gold topography in the cyt c/COOH SAM/gold system. COOH SAMs were prepared from 14-mercaptotetradecanoic acid and 11-mercaptoundecanoic acid on a variety of substrates including evaporated, bulk, single crystal, and epitaxially grown gold on mica. These substrates encompassed a wide range of surface roughness. As the topography of the gold became smoother, SAMs exhibited an increased ability to …

A Mössbauer Spectral Study Of The Magnetic Properties Of Ho₂Fe₁₇ And Ho₂Fe₁₇D₃.₈, Gary J. Long, Olivier Isnard, Fernande Grandjean

Chemistry Faculty Research & Creative Works

The Mössbauer spectra of Ho₂Fe₁₇ and Ho₂Fe₁₇D_3.8 have been measured between 4.2 and 295 K and analyzed with a model which takes into account both the disordered nonstoichiometric hexagonal Th₂Ni₁₇-like structure and the basal orientation of the iron magnetic moments. The isomer shifts of the five crystallographically inequivalent iron sites in both Ho₂Fe₁₇ and Ho₂Fe₁₇D_3.8 follow the sequence of Wigner-Seitz cell volumes and their temperature dependence follows the typical second-order Doppler shift. An increase in the weighted average isomer shift …

A Post-Amadori Inhibitor Pyridoxamine Also Inhibits Chemical Modification Of Proteins By Scavenging Carbonyl Intermediates Of Carbohydrate And Lipid Degradation, Paul A. Voziyan, Thomas O. Metz, John W. Baynes, Billy G. Hudson

Faculty Publications

Reactive carbonyl compounds are formed during autoxidation of carbohydrates and peroxidation of lipids. These compounds are intermediates in the formation of advanced glycation end products (AGE) and advanced lipoxidation end products (ALE) in tissue proteins during aging and in chronic disease. We studied the reaction of carbonyl compounds glyoxal (GO) and glycolaldehyde (GLA) with pyridoxamine (PM), a potent post-Amadori inhibitor of AGE formation in vitro and of development of renal and retinal pathology in diabetic animals. PM reacted rapidly with GO and GLA in neutral, aqueous buffer, forming a Schiff base intermediate that cyclized to a hemiaminal adduct by intramolecular …

Magnetic And Mössbauer Spectral Evidence For The Suppression Of The Magnetic Spin Reorientation In Tm₂Fe₁₇ By Deuterium, Fernande Grandjean, Olivier Isnard, Gary J. Long

Chemistry Faculty Research & Creative Works

The structural and magnetic properties of Tm₂Fe₁₇ and Tm₂Fe₁₇D_3.2 are investigated by means of x-ray-diffraction, thermal, and ac magnetic susceptibility measurements, and iron-57 Mössbauer spectroscopy. Both compounds crystallize in a hexagonal P6₃/mmc space group with a Th₂Ni₁₇-like structure. Deuterium insertion into Tm₂Fe₁₇ induces large increases in the unit-cell volume, the saturation magnetization, and the ordering temperature. The unit-cell expansion is anisotropic, with a larger increase in the a lattice parameter than the c lattice parameter. A spin reorientation is observed at 90 K …

Potent Enantioselective Auxin: Indole-3-Succinic Acid, Daniel W. Armstrong, Yan Song Liu, Lingfeng He, K. Helen Ekborg-Ott, Charles L. Barnes, Charles F. Hammer

Chemistry Faculty Research & Creative Works

Low levels of synthetic auxins are used as root growth promoters for a wide variety of botanicals. When properly used, they can produce earlier and more prolific root growth. Indole-3-succinic acid (ISA) is a chiral compound that can be synthesized as a racemate. Its enantiomers were resolved by both chromatography and diastereomeric crystallization. The absolute configuration of each enantiomer was determined by X-ray crystallography and then tested for auxin activity. The relative effectiveness of the ISA enantiomers was determined and compared to the achiral synthetic auxin indole-3-butyric acid and to the natural auxin indole-3-acetic acid.

Electrochemistry And Spectroscopy Of Sulfate And Thiosulfate Complexes Of Iron Porphyrins, Philip Walter Crawford, Michael D. Ryan

Chemistry Faculty Research and Publications

The electrochemical and spectroscopic properties of the complex formed by the addition of thiosulfate to ferric porphyrins were examined. The NMR spectrum of the thiosulfate–ferric porphyrin complex was consistent with a high-spin ferric complex, while the EPR spectrum at liquid nitrogen temperatures indicated that the complex under these conditions was low-spin. Such behavior has been previously observed for other ferric porphyrin complexes. The visible spectra were characterized by a shift in the Soret band to higher energies, with smaller changes in the longer wavelength region. The complex was reasonably stable in DMF, but slowly reduced over several hours to Fe …

Collision-Induced Electronic Energy Transfer From V=0 Of The E(0+G) Ion-Pair State In I2: Collisions With He And Ar, Christopher J. Fecko , '98, Miriam Arak Freedman , '00, Thomas Alex Stephenson

Chemistry & Biochemistry Faculty Works

The electronic energy transfer pathways that occur following collisions between I-2 in the E ion-pair electronic state (v = 0, J = 55) and He and Ar atoms have been determined. The nearby D, D', and beta ion-pair states are populated, but with relative branching ratios that vary with the rare gas collision partner. In He/I-2 collisions, the D state is preferentially populated, while Ar/I-2 collisions preferentially populate the beta electronic state. Bimolecular rate constants and effective hard sphere collision cross sections have been determined for each channel; the cross sections range from 7.0 +/- 1.0 Angstrom(2) for populating the …

Anchoring The Water Dimer Potential Energy Surface With Explicitly Correlated Computations And Focal Point Analyses, Gregory S. Tschumper, Matthew L. Leininger, Brian C. Hoffman, Edward F. Valeev, Henry F. Schaefer, Martin Quack

Chemistry Faculty Research & Creative Works

The extensive ab initio quantum chemical study of ten stationary point on the water dimer potential energy surface (PES) was discussed. The geometry optimizations were carried out using the CCSD(T) method in conjunction with the [TZ2P(f,d) + dif] basis set. The study showed that the optimized structures of (H₂O)₂ PES were quite similar to those obtained at the MP2 level with much smaller basis sets and the number of imaginary vibrational frequencies or hessian index of each stationary point was unchanged despite fairly significant geometrical differences for some of the optimized structures.

Photoelectron Spectroscopy Of Clh2 - And Cld2 -: A Probe Of The Cl+H2 Van Der Waals Well And Spin-Orbit Excited States, Michael J. Ferguson, Giovanni Meloni, Harry Gomez, D M. Neumark

Chemistry Faculty Publications

Photoelectron (PE) spectra of ClH−2 and ClD−2 were measured at 299 nm (4.154 eV). Photodetachment of these anions accesses the prereactive van der Waals well on the ground stateCl+H2potential energy surface, as well as the low-lying spin–orbit excited states resulting from the interaction of Cl and Cl* with H2. The PE spectra are dominated by two relatively narrow peaks corresponding to transitions to the neutral Cl⋅H2 and Cl*⋅H2 complexes. The energetics and widths of these features are interpreted in terms of the properties of the anion and neutral potential energy surfaces.