Molecular beam scattering experiments with polar molecules. 1. Differential elastic scattering of H2+NH3 and H2+H2O

International Nuclear Information System (INIS)

Bickes, R.W. Jr.; Scoles, G.; Smith, K.M.

1974-01-01

Differential elastic scattering cross sections with well resolved quantum oscillations have been measuremed for the systems H 2 +NH 3 and H 2 +H 2 O. Assuming a spherically symmetric interaction the data show that a simple spherical potential (i.e. Lennard-Jones) does not properly describe the scattering

Evaluation of the phase composition of (NH4)2SO4 + (NH4)H2PO4 mixtures by X-ray diffractometry

International Nuclear Information System (INIS)

Ortiz, Angel L.; Cumbrera, Francisco L.; Perez, Jose; Vas, Beatriz del; Perez, Eduardo

2009-01-01

The phase composition of standard (NH 4 ) 2 SO 4 + (NH 4 )H 2 PO 4 mixtures was investigated by X-ray diffractometry (XRD) using the internal-standard, reference-intensity-ratio, and Rietveld methods. It was found that the Rietveld method yields the most accurate phase-composition measurements, with an average error of ∼2 wt.%. It was also found that the internal-standard method is only effective in determining the phase composition if the calibration curve for (NH 4 )H 2 PO 4 is used, giving an average error of ∼6.5 wt.%. On the contrary, the internal-standard method with the calibration curve of the (NH 4 ) 2 SO 4 phase and the reference-intensity-ratio method are not valid. The inappropriateness of these two methods was attributed to graininess in the (NH 4 ) 2 SO 4 phase, with the attendant deviation of its diffracted intensities from the theoretical values. Direct scanning electron microscopy observations of the morphology of the powder particles in the mixtures showed clear evidence of the large agglomerates formed because the individual powder particles are partially sintered together during milling, thus corroborating the graininess determined by the XRD analyses. Finally, the implications of the present study for the quantitative phase-composition analysis of (NH 4 ) 2 SO 4 + (NH 4 )H 2 PO 4 mixtures, which are of great technological importance for the fire prevention industry, are discussed.

Equilibrium Measurements of the NH3-CO2-H2O System: Speciation Based on Raman Spectroscopy and Multivariate Modeling

Directory of Open Access Journals (Sweden)

Maths Halstensen

2017-01-01

Full Text Available Liquid speciation is important for reliable process design and optimization of gas-liquid absorption process. Liquid-phase speciation methods are currently available, although they involve tedious and time-consuming laboratory work. Raman spectroscopy is well suited for in situ monitoring of aqueous chemical reactions. Here, we report on the development of a method for speciation of the CO2-NH3-H2O equilibrium using Raman spectroscopy and PLS-R modeling. The quantification methodology presented here offers a novel approach to provide rapid and reliable predictions of the carbon distribution of the CO2-NH3-H2O system, which may be used for process control and optimization. Validation of the reported speciation method which is based on independent, known, NH3-CO2-H2O solutions shows estimated prediction uncertainties for carbonate, bicarbonate, and carbamate of 6.45 mmol/kg H2O, 34.39 mmol/kg H2O, and 100.9 mmol/kg H2O, respectively.

Synthesis and structural characterization of two cobalt phosphites: 1-D (H3NC6H4NH3)Co(HPO3)2 and 2-D (NH4)2Co2(HPo3)3

International Nuclear Information System (INIS)

Cheng, C.-C.; Chang, W.-K.; Chiang, R.-K.; Wang, S.-L.

2010-01-01

Two new cobalt phosphites, (H 3 NC 6 H 4 NH 3 )Co(HPO 3 ) 2 (1) and (NH 4 ) 2 Co 2 (HPO 3 ) 3 (2), have been synthesized and characterized by single-crystal X-ray diffraction. All the cobalt atoms of 1 are in tetrahedral CoO 4 coordination. The structure of 1 comprises twisted square chains of four-rings, which contain alternating vertex-shared CoO 4 tetrahedra and HPO 3 groups. These chains are interlinked with trans-1,4-diaminocyclohexane cations by hydrogen bonds. The 2-D structure of 2 comprises anionic complex sheets with ammonium cations present between them. An anionic complex sheet contains three-deck phosphite units, which are interconnected by Co 2 O 9 to form complex layers. Magnetic susceptibility measurements of 1 and 2 showed that they have a weak antiferromagnetic interaction. - Graphical abstract: The 2-D structure of (NH 4 ) 2 Co 2 (HPO 3 ) 3 comprises anionic complex sheets with ammonium cations present between them. An anionic complex sheet contains three-deck phosphite units, which are interconnected by dimmeric Co 2 O 9 to form complex layers.

A neodymium(III)-ammonium complex involving oxalate and carbonate ligands: (NH4)2[Nd2(C2O4)3(CO3)(H2O)].H2O.

Science.gov (United States)

Trombe, Jean-Christian; Galy, Jean; Enjalbert, Renée

2002-10-01

The title compound, diammonium aqua-mu-carbonato-tri-mu-oxalato-dineodymium(III) hydrate, (NH(4))(2)[Nd(2)(CO(3))(C(2)O(4))(3)(H(2)O)].H(2)O, involving the two ligands oxalate and carbonate, has been prepared hydrothermally as single crystals. The Nd atoms form a tetranuclear unit across the inversion centre at (1/2, 1/2, 1/2). Starting from this tetranuclear unit, the oxalate ligands serve to develop a three-dimensional network. The carbonate group acts as a bis-chelating ligand to two Nd atoms, and is monodentate to a third Nd atom. The oxalate groups are all bis-chelating. The two independent Nd atoms are ninefold coordinated and the coordination polyhedron of these atoms is a distorted monocapped antiprism.

Keggin type polyoxometalate H4[αSiW12O40].nH2O as intercalant for hydrotalcite

Directory of Open Access Journals (Sweden)

Neza Rahayu Palapa

2017-06-01

Full Text Available The synthesis of hydrotalcite and polyoxometalate H4[αSiW12O40].nH2O with the ratio (2:1, (1:1, (1:2 and (1:3 has been done. The product of intercalation was characterized using FT-IR spectrophotometer, XRD, and TG-DTA. Polyoxometalate H4[αSiW12O40].nH2O intercalated layered double hydroxide was optimised to use as adsorbent Congo red dye. Characterization using FT-IR was not showing the optimal insertion process. The result using XRD characterization was showed successful of polyoxometalate H4[αSiW12O40].nH2O inserted layered double hydroxide with a ratio (1:1 which the basal spacing was expanded from 7,8 Ȧ to 9,81 Ȧ. Furthermore, the thermal analysis was performed using TG-DTA. The result show that the decomposition of polyoxometalate H4[αSiW12O40].nH2O intercalated  hydrotalcite with ratio (1:1 was occured at 80oC to 400oC with a loss of OH in the layer at 150oC to 220oC, and then the decomposition of the compound polyoxometalate H4[αSiW12O40].nH2O at 350oC to 420oC. Keywords: Hydrotalcite, Layered Double Hydroxide, Polyoxometalate, Intercalation

Relationship between interlayer hydration and photocatalytic water splitting of A'1-xNaxCa2Ta3O10.nH2O (A'=K and Li)

International Nuclear Information System (INIS)

Mitsuyama, Tomohiro; Tsutsumi, Akiko; Sato, Sakiko; Ikeue, Keita; Machida, Masato

2008-01-01

Partial replacement of alkaline metals in anhydrous KCa 2 Ta 3 O 10 and LiCa 2 Ta 3 O 10 was studied to control interlayer hydration and photocatalytic activity for water splitting under UV irradiation. A' 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O (A'=K and Li) samples were synthesized by ion exchange of CsCa 2 Ta 3 O 10 in mixed molten nitrates at 400 deg. C. In K 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O, two phases with the orthorhombic (C222) and tetragonal (I4/mmm) structures were formed at x≤0.7 and x≥0.5, respectively. Upon replacement by Na + having a larger enthalpy of hydration (ΔH h 0 ), the interlayer hydration occurred at x≥0.3 and the hydration number (n) was increased monotonically with an increase of x. Li 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O showed a similar hydration behavior, but the phase was changed from I4/mmm (x 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O exhibited the activity increasing in consistent with n, whereas Li 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O exhibited the activity maximum at x=0.77, where the rates of H 2 /O 2 evolution were nearly doubled compared with those for end-member compositions (x=0 and 1). - Graphical abstract: The partial substitution of Na in the interlayer of anhydrous-layered perovskite has been found as useful structural modification toward highly active hydrated photocatalysts

Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 4. Individual Heats of Adsorption of Adsorbed H 2 O Species on Sulfate-Free and Sulfated TiO 2 Supports

KAUST Repository

Giraud, Franç ois; Couble, Julien; Geantet, Christophe; Guilhaume, Nolven; Puzenat, Eric; Gros, Sé bastien; Porcheron, Lynda; Kanniche, Mohamed; Bianchi, Daniel

2015-01-01

© 2015 American Chemical Society. The present study is a part of an experimental microkinetic approach of the removal of NOx from coal-fired power plants by reduction with NH3 on V2O5/WO3/TiO2 catalysts (NH3-selective catalytic reduction, NH3-SCR). It is dedicated to the characterization of the heats of adsorption of molecularly adsorbed H2Oads species formed on sulfate-free and sulfated TiO2 supports. Water, which is always present during the NH3-SCR, may be in competition and/or react (formation of NH4⁺) with the adsorbed NH3 species controlling the coverage of the adsorbed intermediate species of the reaction. Mainly, an original experimental procedure named adsorption equilibrium infrared spectroscopy (AEIR) previously used for the adsorption of NH3 species on the same solids is adapted for the adsorption of H2O. At Ta = 300 K and for PH2 O ≤ 1 kPa, three main H2Oads species are formed (associated with a minor amount of dissociated H2O species) on the two TiO2 solids. The species are identified by the positions of their IR bands in the 3750-3000 cm^-1 range. Considering the decreasing order of stability, they are (a) coordinated to strong (L2) and weak (L1) Lewis sites and denoted H2O ads-L2 and H2Oads-L1, respectively, and (b) hydrogen bonded to the H2Oads-L species and on O^2-/OH sites of the solids (denoted H2Owads). The three species have a common well-defined δH2O IR band at a position in the range 1640-1610 cm^-1 according to the total coverage of the surface. According to the AEIR method, the evolution of the intensity of this IR band during the increase in the adsorption temperature Ta in isobaric condition provides the evolution of the average coverage of the three species and then to their individual heats of adsorption as a function of their coverage. It is shown that there are no significant differences on the two TiO2 solids. In particular, the heat of adsorption of the H2Oads-L2 species varies from �

Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 4. Individual Heats of Adsorption of Adsorbed H 2 O Species on Sulfate-Free and Sulfated TiO 2 Supports

KAUST Repository

Giraud, François

2015-07-16

© 2015 American Chemical Society. The present study is a part of an experimental microkinetic approach of the removal of NOx from coal-fired power plants by reduction with NH3 on V2O5/WO3/TiO2 catalysts (NH3-selective catalytic reduction, NH3-SCR). It is dedicated to the characterization of the heats of adsorption of molecularly adsorbed H2Oads species formed on sulfate-free and sulfated TiO2 supports. Water, which is always present during the NH3-SCR, may be in competition and/or react (formation of NH4⁺) with the adsorbed NH3 species controlling the coverage of the adsorbed intermediate species of the reaction. Mainly, an original experimental procedure named adsorption equilibrium infrared spectroscopy (AEIR) previously used for the adsorption of NH3 species on the same solids is adapted for the adsorption of H2O. At Ta = 300 K and for PH2 O ≤ 1 kPa, three main H2Oads species are formed (associated with a minor amount of dissociated H2O species) on the two TiO2 solids. The species are identified by the positions of their IR bands in the 3750-3000 cm^-1 range. Considering the decreasing order of stability, they are (a) coordinated to strong (L2) and weak (L1) Lewis sites and denoted H2O ads-L2 and H2Oads-L1, respectively, and (b) hydrogen bonded to the H2Oads-L species and on O^2-/OH sites of the solids (denoted H2Owads). The three species have a common well-defined δH2O IR band at a position in the range 1640-1610 cm^-1 according to the total coverage of the surface. According to the AEIR method, the evolution of the intensity of this IR band during the increase in the adsorption temperature Ta in isobaric condition provides the evolution of the average coverage of the three species and then to their individual heats of adsorption as a function of their coverage. It is shown that there are no significant differences on the two TiO2 solids. In particular, the heat of adsorption of the H2Oads-L2 species varies from �

H{sub 2} assisted NH{sub 3}-SCR over Ag/Al{sub 2}O{sub 3} for automotive applications

Energy Technology Data Exchange (ETDEWEB)

Fogel, S.

2013-05-15

The up-coming strict emission legislation demands new and improved catalysts for diesel vehicle deNO{sub x}. The demand for low-temperature activity is especially challenging. H{sub 2}-assisted NH{sub 3}-SCR over Ag/Al{sub 2}O{sub 3} has shown a very promising low-temperature activity and a combination of Ag/Al{sub 2}O{sub 3} and Fe-BEA can give a high NO{sub x} conversion in a broad temperature window without the need to dose H{sub 2} at higher temperatures. The aim of this study has been to investigate the combined Ag/Al{sub 2}O{sub 3} and Fe-BEA catalyst system both at laboratory-scale and in full-scale engine bench testing. The catalysts were combined both in a sequential dual-bed layout and a dual-layer layout where the catalysts were coated on top of each other. The Ag/Al{sub 2}O{sub 3} catalyst was also investigated with the aim of improving the sulphur tolerance and low-temperature activity by testing different alumina-supports. A large focus of this study has been the preparation of monolithic catalyst bricks for the catalyst testing. A high SBET and higher Ag loading gave a high sulphur tolerance and activity. It was believed that the high S{sub BET} is needed to give a higher NH{sub 3} adsorption capacity, necessary for the SCR reaction. A higher Ag loading gives more Ag sites and probably a favourable Ag dispersion. Testing with sulphur gave an increased activity of the catalysts. Testing of monolithic catalysts showed a similar activity enhancement after a few standard test cycles. A change in the dispersion or state of Ag can be possible reasons for the activation seen and the activation was believed to be related to Ag and not the alumina. Small-scale laboratory testing showed that it was preferred to have Ag/Al{sub 2}O{sub 3} either upstream or as the outer layer of Fe-BEA. This was attributed to complete NH{sub 3} oxidation over Fe-BEA giving a deficit of NH{sub 3} over the Ag/Al{sub 2}O{sub 3} if it was placed downstream or as the inner layer

Rotational Spectroscopy of the NH{sub 3}–H{sub 2} Molecular Complex

Energy Technology Data Exchange (ETDEWEB)

Surin, L. A.; Schlemmer, S. [I. Physikalisches Institut, University of Cologne, Zülpicher Str. 77, D-50937 Cologne (Germany); Tarabukin, I. V. [Institute of Spectroscopy of Russian Academy of Sciences, Fizicheskaya Str. 5, 108840 Troitsk, Moscow, Russia (Russian Federation); Breier, A. A.; Giesen, T. F. [Institute of Physics, University of Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel (Germany); McCarthy, M. C. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Avoird, A. van der, E-mail: surin@ph1.uni-koeln.de, E-mail: A.vanderAvoird@theochem.ru.nl [Theoretical Chemistry, Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands)

2017-03-20

We report the first high resolution spectroscopic study of the NH{sub 3}–H{sub 2} van der Waals molecular complex. Three different experimental techniques, a molecular beam Fourier transform microwave spectrometer, a millimeter-wave intracavity jet OROTRON spectrometer, and a submillimeter-wave jet spectrometer with multipass cell, were used to detect pure rotational transitions of NH{sub 3}–H{sub 2} in the wide frequency range from 39 to 230 GHz. Two nuclear spin species, ( o )-NH{sub 3}–( o )-H{sub 2} and ( p )-NH{sub 3}–( o )-H{sub 2}, have been assigned as carriers of the observed lines on the basis of accompanying rovibrational calculations performed using the ab initio intermolecular potential energy surface (PES) of Maret et al. The experimental spectra were compared with the theoretical bound state results, thus providing a critical test of the quality of the NH{sub 3}–H{sub 2} PES, which is a key issue for reliable computations of the collisional excitation and de-excitation of ammonia in the dense interstellar medium.

Formation of nitrogen complexes when [Ru(NH3)5H2O]2+ ion reaction with diazo-acetic ester and aromatic salts of diazonium

International Nuclear Information System (INIS)

Shur, V.B.; Tikhonova, I.A.; Vol'pin, M.E.

1978-01-01

A possibility of formation of nitrogen complexes during transition metal compound interaction with aliphatic and aromatic diazo compounds is studied. It is shown that at the interaction of [Ru(NH 3 ) 5 H 2 O] 2+ with diazo-acetic ester in water (pH7) at 20 deg, quick splitting of the CN-bond in the ester molecule takes place with the formation of [Ru(NH 3 ) 5 N 2 ] 2+ and [(NH 3 ) 5 RuN 2 Ru(NH 3 ) 5 ] 4+ (NRRN) nitrogen complexes. The sum yield of complexes comprises 86% taking into acount diazo-acetic ester. Aromatic salts of diazonium, n-O 3 SC 6 H 4 N 2 and p-quinone diazide react with the [Ru(NH 3 ) 5 H 2 O] 2+ excess forming NRRN (the yield equals 40-53%). The reaction mechanism is discussed

Tetraammineplatinum(II) aquapentachloroiridate(III) dihydrate, [Pt(NH3)4][IrCl5(H2O)

International Nuclear Information System (INIS)

Garnier, E.; Bele, M.

1994-01-01

The crystal is built up from planar Pt(NH 3 ) 4 2+ cations, octahedral IrCl 5 (H 2 O) 2- anions and two H 2 O molecules. The coordination of these ions is 6/6, thus leading to a NaCl crystal structure. Electrostatic interactions and N..Cl, N..O and N..N short contacts (possible hydrogen bonds) take part in the packing of the structure and form a three-dimensional network. (orig.)

Synthesis and structure of a 1,6-hexyldiamine heptaborate, [H3N(CH2)6NH3][B7O10(OH)3

International Nuclear Information System (INIS)

Yang Sihai; Li Guobao; Tian Shujian; Liao Fuhui; Xiong Ming; Lin Jianhua

2007-01-01

A new 1,6-hexyldiamine heptaborate, [H 3 N(CH 2 ) 6 NH 3 ][B 7 O 10 (OH) 3 ] (1), has been solvothermally synthesized and characterized by single-crystal X-ray diffraction, FTIR, elemental analysis, and thermogravimetric analysis. Compound 1 crystallizes in monoclinic system, space group P2 1 /n with a=8.042(2) A, b=20.004(4) A, c=10.103(2) A, and β=90.42(3) deg. The anionic [B 7 O 10 (OH) 3 ] n 2n- layers are interlinked via hydrogen bonding to form a 3D supramolecular network containing large channels, in which the templated [H 3 N(CH 2 ) 6 NH 3 ] 2+ cations are located. - Graphical abstract: A layered 1,6-hexyldiamine heptaborate, [H 3 N(CH 2 ) 6 NH 3 ][B 7 O 10 (OH) 3 ], was solvothermally synthesized at 150 deg. C. It is a layer borate and crystallized in monoclinic space group P2 1 /n with a=8.042(2) A, b=20.004(4) A, c=10.103(2) A, β=90.42(3) deg

Photolysis of H2O-H2O2 Mixtures: The Destruction of H2O2

Science.gov (United States)

Loeffler, M. J.; Fama, M.; Baragiola, R. A.; Carlson, R. W.

2013-01-01

We present laboratory results on the loss of H2O2 in solid H2O + H2O2 mixtures at temperatures between 21 and 145 K initiated by UV photolysis (193 nm). Using infrared spectroscopy and microbalance gravimetry, we measured the decrease of the 3.5 micrometer infrared absorption band during UV irradiation and obtained a photodestruction cross section that varies with temperature, being lowest at 70 K. We use our results, along with our previously measured H2O2 production rates via ionizing radiation and ion energy fluxes from the spacecraft to compare H2O2 creation and destruction at icy satellites by ions from their planetary magnetosphere and from solar UV photons. We conclude that, in many cases, H2O2 is not observed on icy satellite surfaces because the H2O2 photodestruction rate is much higher than the production rate via energetic particles, effectively keeping the H2O2 infrared signature at or below the noise level.

Synthesis and structure of heptaaqua(nitrilotris(methylenephosphonato))(dibarium)sodium monohydrate [Na(H{sub 2}O){sub 3}(μ{sup 6}-NH(CH{sub 2}PO{sub 3}){sub 3})(μ-H{sub 2}O){sub 3}Ba{sub 2}(H{sub 2}O)] · H{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Somov, N. V., E-mail: somov@phys.unn.ru [Lobachevsky State University of Nizhny Novgorod (Russian Federation); Chausov, F. F., E-mail: xps@ftiudm.ru [Russian Academy of Sciences, Physical–Technical Institute, Ural Branch (Russian Federation); Zakirova, R. M., E-mail: ftt@udsu.ru [Udmurt State University (Russian Federation)

2017-03-15

Crystals of the monohydrate form of heptaaqua(nitrilotris(methylenephosphonato))(dibarium) sodium [Na(H{sub 2}O{sub )3}(µ{sup 6}-NH(CH{sub 2}PO{sub 3}){sub 3})(µ-H{sub 2}O){sub 3}Ba{sub 2}(H{sub 2}O)] · H{sub 2}O are obtained; space group P2{sub 1}/c, Z = 4; a = 13.9117(10) Å, b = 11.54030(10) Å, and c = 24.1784(17) Å, ß = 148.785(18)°. The Na atom is coordinated octahedrally by one oxygen atom of a phosphonate group and five water molecules, including two bridging molecules. Ba atoms occupy two inequivalent crystallographic positions with coordination number eight and nine. The coordination spheres of both Ba atoms include two water molecules. Each ligand is bound to one Na atom and five Ba atoms forming three Ba–O–P–O and five Ba–O–P–C–N–C–P–O chelate cycles. In addition to the coordination bonds, molecules, including the solvate water molecule, are involved in hydrogen bonds in the crystal packing.

Bulk Kosterlitz-Thouless Type Molecular Superconductor β″-(BEDT-TTF)2[(H2O)(NH4)2Cr(C2O4)3]·18-crown-6.

Science.gov (United States)

Martin, Lee; Lopez, Jordan R; Akutsu, Hiroki; Nakazawa, Yasuhiro; Imajo, Shusaku

2017-11-20

A new molecular superconductor, β″-(BEDT-TTF) 2 [(H 2 O)(NH 4 ) 2 Cr(C 2 O 4 ) 3 ]·18-crown-6, has been synthesized from the organic donor molecule BEDT-TTF with the anion Cr(C 2 O 4 ) 3 3- . The crystal structure consists of conducting organic layers of BEDT-TTF molecules which adopt the β″ packing motif (layer A), layers of NH 4 + and Λ-Cr(C 2 O 4 ) 3 3- (layer B), layers of (H 2 O)(NH 4 )18-crown-6 (layer C), and layers of NH 4 + and Δ-Cr(C 2 O 4 ) 3 3- (layer D) which produce a superstructure with a repeating pattern of ABCDABCDA. As a result of this packing arrangement, this is the 2D superconductor with the widest gap between conducting layers where only a single donor packing motif is present (β″). Superconducting critical temperatures at ambient pressure observed by electrical transport and magnetic measurements are 4.0-4.9 and 2.5 K, respectively. The strong 2D nature of this system, the broad transition to T zero at 1.8K, and the transition of α of V ∝ I α from 1 to 3 on I-V curves strongly suggest that the superconducting transition is very close to a Kosterlitz-Thouless transition. The magnetic field dependence of the superconducting critical temperature parallel to the conducting plane gives an upper critical field μ 0 H c2∥ > 8 T, which is over the calculated Pauli-Clogston limit for this material.

Effect of Al in the H2 storage properties of Li-NH system

International Nuclear Information System (INIS)

Fernandez Albanesi, L; Lago, Marcelo N; Arneodo Larochette, P; Gennari, F.C

2012-01-01

In this work is studied the effect of the addition of aluminum on the properties of hydrogen absorption-desorption system LiNH 2 : 1,5 LiH. The samples were prepared adding the element Al to the system LiNH 2 :1.5 LiH in different ways (as aluminum metal, as aluminum chloride and as lithium aluminum hydride). In all these mixtures was maintained the concentration of Al in 1 mol%. A good distribution of Al is achieved by mechanical milling. Quantitative hydrogen absorption and desorption were measured by volumetric method with a Sieverts-type apparatus in the temperature range of 250 to 300 o C and 700 kPa of H 2 pressure. The systems with Al showed better absorption kinetics and greater stability after cycles of hydrogen absorption-desorption. The hydrogen capacity achieved by these samples was 5.3 wt% at 300 and 275 o C. The mixture with AlCl 3 displays the same characteristics at 250 o C, showing the better H 2 storage properties

Ion-molecule reactions in the binary mixture of ethylene oxide and trioxane, 2

International Nuclear Information System (INIS)

Kumakura, Minoru; Arakawa, Kazuo; Sugiura, Toshio.

1978-01-01

The ion-molecule reactions in the binary mixture of ethylene oxide and trioxane have been studied with use of a modified time-of-flight mass spectrometer. As cross-reaction product ions, C 3 H 5 O 2 + , C 3 H 6 O 2 +sup(, and C**3**H**7**O**2**)+sup( were observed under the conditions of long delay times and elevated pressure. It was found that these ions are formed by the dissociation of unstable intermediate-complex resulting from the reaction of ethylene oxide molecular ion with trioxane. It was proposed that the complex is of cyclic structure in which positive charge is delocalized. From the consideration of isotopic distribution of the product ions in ethylene-d**4** oxide-trioxane mixtures, the skeletal structures of the product ions were investigated. The rate constants of the formation reactions of C**3**H**5**O**2**)+sup(, C**3**H**6**O**2**)+sup(, and C**3**H**7**O**2**)+sup( in ethylene oxide-trioxane mixtures were found to be 2.20 x 10)-10sup(, 2.61 x 10)-10sup(, and 1.74 x 10)-10sup( cm)3sup( molecule)-1sup(s)-1 , respectively. (auth.)

Modeling impacts of NH3 on uptake of H2SO4 by charged nucleating nanoparticles in the Earth's atmosphere

International Nuclear Information System (INIS)

Nadykto, A. B.; Nazarenko, K. M.; Markov, P. N.; Yu, F.

2016-01-01

The understanding of the role of ammonia, a well-known stabilizer of binary sulfuric acid-water clusters, in the gas-to-nanoparticle conversion in the Earth atmosphere is critically important for the assessment of aerosol radiative forcing associated with the climate changes. The sulfuric acid H 2 SO 4 is present in the atmosphere in the form of the gas-phase hydrates (H 2 SO 4 )(H 2 O) n , whose interaction with NH 3 leads to the formation of more stable bisulfate clusters (NH 3 )(H 2 SO 4 )(H 2 O) n . Although the impact of NH 3 on the thermochemical stability of binary clusters nucleating homogeneously has been studied in some detail in the past, the effect of ammonia on other microphysical properties relevant to nucleation remains insufficiently well understood. In the present study, the effect of ammonia on the electrical dipole moment controlling the nucleation of airborne ions via the dipole-charge interaction has been investigated using the Density Functional Theory (DFT), ab initio MP2 and model chemistry G3 methods. The presence of ammonia in (H 2 SO 4 )(H 2 O) n is found to lead to very large enhancement in the dipole moment, which exceeds 2.0-2.5 Debyes (∼60-80%), 3.7-5.0 Debyes (∼90-180%), 1.4-4.5 Debyes (∼50-150%) and 2.1-5.5 Debyes (∼60-700%) for n = 0, n = 1, n = 2 and n = 3, respectively. The implications of this include the significantly increased uptake of the sulfuric acid, the key atmospheric nucleation precursor, by airborne ions and neutrals (due to dipole-dipole interaction), enhanced nucleation rates and the elevated production of ultrafine particles, which cause adverse health impacts.

NH4In(SeO4)2x4H2O crystal structure interpretation

International Nuclear Information System (INIS)

Soldatov, E.A.; Kuz'min, Eh.A.; Ilyukhin, V.V.

1979-01-01

The rhomb method has been applied to interpret the structure of monoclinic ammonium indium selenate NH 4 In(SeO 4 ) 2 x4H 2 O the elementary cell of which contains Z=4 formula units (a=10.728, b=9.434, c=11.086 A, γ=101.58). The space group is P2 1 /b. The structure foundation is composed of [In(SeO 4 ) 2 x2H 2 O] 1- mixed layers parallel to (100). ''Free'' H 2 O molecules and NH 4 + cations are situated between the layers

Behavior of sheet-like crystalline ammonium trivanadate hemihydrate (NH4V3O8×0.5H2O) as a novel ammonia sensing material

International Nuclear Information System (INIS)

Leonardi, S.G.; Primerano, P.; Donato, N.; Neri, G.

2013-01-01

This work reports the use of ammonium trivanadate hemihydrate (NH 4 V 3 O 8 ×0.5H 2 O) as a novel sensing material for ammonia resistive sensors. It was prepared by a simple and fast hydrothermal method from V 2 O 5 as a precursor and characterized by SEM, FT-IR, XRD and TG techniques. The as-synthesized material showed a sheet-like morphology and was found thermally stable up to 250–280 °C. It reacted promptly and irreversibly when exposed to ammonia at room temperature. A full reversibility was instead registered undergoing the formed ammonia adduct at a temperature higher than 200 °C. A NH 4 V 3 O 8 ×0.5H 2 O-based resistive gas sensor was fabricated and its sensing properties were evaluated. Experimental results obtained have given a preliminary demonstration of the feasibility of using NH 4 V 3 O 8 ×0.5H 2 O as a novel ammonia sensing material since it yields several advantages including easy synthesis of the sensing layer, good sensitivity and reproducibility and fast response. - Graphical abstract: Sheet-like morphology of the synthesized trivanadate hemihydrate (NH 4 V 3 O 8 ×0.5H 2 O). Inset: Its electrical response to different ammonia concentrations in air. - Highlights: • A simple hydrothermal method for the fast synthesis of trivanadate hemihydrate (NH 4 V 3 O 8 ×0.5H 2 O) is reported. • Sheet particles could be obtained. • A preliminary demonstration of the feasibility of using NH 4 V 3 O 8 ×0.5H 2 O as a novel ammonia sensing material is presented

H2-H2O-HI Hydrogen Separation in H2-H2O-HI Gaseous Mixture Using the Silica Membrane

International Nuclear Information System (INIS)

Pandiangan, Tumpal

2002-01-01

It was evaluated aiming at the application for hydrogen iodide decomposition in the thermochemical lS process. Porous alumina tube having pore size of 0.1 μm was modified by chemical vapor deposition using tetraethoxysilane. The permeance single gas of He, H 2 , and N 2 was measured at 300-600 o C. Hydrogen permeance of the modified membrane at a permeation temperature of 600 o C was about 5.22 x 10 -08 mol/Pa m 2 s, and 3.2 x 10 -09 of using gas mixture of H 2 -H 2 O-HI, where as HI permeances was below 1 x 10 -10 mol/Pa m 2 s. The Hydrogen permeance relative was not changed after 25 hours exposure in a mixture of H 2 -H 2 O-HI gas at the temperature of 450 o C. (author)

Solubility Modeling of the Binary Systems Fe(NO3)3–H2O, Co(NO3)2–H2O and the Ternary System Fe(NO3)3–Co(NO3)2–H2O with the Extended Universal Quasichemical (UNIQUAC) Model

DEFF Research Database (Denmark)

Arrad, Mouad; Kaddami, Mohammed; Goundali, Bahija El

2016-01-01

Solubility modeling in the binary system Fe(NO3)3–H2O, Co(NO3)2–H2O and the ternary system Fe(NO3)3–Co(NO3)2–H2O is presented. The extended UNIQUAC model was applied to the thermodynamic assessment of the investigated systems. The model parameters obtained were regressed simultaneously using...... the available databank but with more experimental points, recently published in the open literature. A revision of previously published parameters for the cobalt ion and new parameters for the iron(III) nitrate system are presented. Based on this set of parameters, the equilibrium constants of hydrates...

Dehydriding and rehydriding properties of Mg(NH2)2-LiH systems

International Nuclear Information System (INIS)

Aoki, M.; Noritake, T.; Nakamori, Y.; Towata, S.; Orimo, S.

2007-01-01

The dehydriding and rehydriding properties of the mixtures of 3Mg(NH 2 ) 2 + nLiH (n = 6, 8, and 12) were investigated by pressure-composition (p-c) isotherm and X-ray diffraction (XRD) measurements in order to clarify the effects of the LiH ratio n on the properties. The amounts of the hydrogen desorbed from the mixtures with n = 6, 8, and 12 were 5.4, 5.1, and 4.5 mass%, respectively; this indicates that the amounts on a unit mass basis decrease with increasing n. However, the molar ratios of the desorbed hydrogen to the mixtures estimated from the amounts were almost equal, and also the features of the p-c isotherms were similar to each other. Moreover, the Li 2 Mg(NH) 2 and LiH phases were observed in XRD profiles of all the mixtures after p-c isotherm measurements. These results suggest that the dehydriding reaction of the mixtures of 3Mg(NH 2 ) 2 + nLiH (n = 6, 8, and 12) under hydrogen pressure is not dominantly affected by the value of n. On the other hand, the amounts of the ammonia desorbed from the mixtures detected by mass spectroscopy decreased with increasing n

Insulators containing CuCl4X22- (X=H2O, NH3) units: Origin of the orthorhombic distortion observed only for CuCl4(H2O)22-

DEFF Research Database (Denmark)

García-Fernández, P.; García Lastra, Juan Maria; Trueba, A.

2012-01-01

The origin of the difference in structure between compounds containing CuCl4X22- (X=H2O, NH3) units is analyzed by means of first-principles calculations. While NH3-containing compounds display tetragonal symmetry, H2O-containing ones display an orthorhombic distortion at low temperature where...... the equatorial Cl- ions are no longer equivalent. Our simulations of optical and vibrational transitions show good agreement with all available experimental optical absorption and Raman data. As a salient feature, the value of the force constant for the B1g mode, K(B1g), driving the orthorhombic distortion......CuCl4(H2O)2 has a local origin....

Densities and apparent molar volumes of atmospherically important electrolyte solutions. 2. The systems H(+)-HSO4(-)-SO4(2-)-H2O from 0 to 3 mol kg(-1) as a function of temperature and H(+)-NH4(+)-HSO4(-)-SO4)2-)-H2O from 0 to 6 mol kg(-1) at 25 °C using a Pitzer ion interaction model, and NH4HSO4-H2O and (NH4)3H(SO4)2-H2O over the entire concentration range.

Science.gov (United States)

Clegg, S L; Wexler, A S

2011-04-21

A Pitzer ion interaction model has been applied to the systems H(2)SO(4)-H(2)O (0-3 mol kg(-1), 0-55 °C) and H(2)SO(4)-(NH(4))(2)SO(4)-H(2)O (0-6 mol kg(-1), 25 °C) for the calculation of apparent molar volume and density. The dissociation reaction HSO(4)(-)((aq)) ↔ H(+)((aq)) + SO(4)(2-)((aq)) is treated explicitly. Apparent molar volumes of the SO(4)(2-) ion at infinite dilution were obtained from part 1 of this work, (1) and the value for the bisulfate ion was determined in this study from 0 to 55 °C. In dilute solutions of both systems, the change in the degree of dissociation of the HSO(4)(-) ion with concentration results in much larger variations of the apparent molar volumes of the solutes than for conventional strong (fully dissociated) electrolytes. Densities and apparent molar volumes are tabulated. Apparent molar volumes calculated using the model are combined with other data for the solutes NH(4)HSO(4) and (NH(4))(3)H(SO(4))(2) at 25 °C to obtain apparent molar volumes and densities over the entire concentration range (including solutions supersaturated with respect to the salts).

Communication: Equivalence between symmetric and antisymmetric stretching modes of NH3 in promoting H + NH3 → H2 + NH2 reaction

Science.gov (United States)

Song, Hongwei; Yang, Minghui; Guo, Hua

2016-10-01

Vibrational excitations of reactants sometimes promote reactions more effectively than the same amount of translational energy. Such mode specificity provides insights into the transition-state modulation of reactivity and might be used to control chemical reactions. We report here a state-of-the-art full-dimensional quantum dynamical study of the hydrogen abstraction reaction H + NH3 → H2 + NH2 on an accurate ab initio based global potential energy surface. This reaction serves as an ideal candidate to study the relative efficacies of symmetric and degenerate antisymmetric stretching modes. Strong mode specificity, particularly for the NH3 stretching modes, is demonstrated. It is further shown that nearly identical efficacies of the symmetric and antisymmetric stretching modes of NH3 in promoting the reaction can be understood in terms of local-mode stretching vibrations of the reactant molecule.

Evidence of amino acid precursors: C-N bond coupling in simulated interstellar CO2/NH3 ices

Science.gov (United States)

Esmaili, Sasan

2015-08-01

Low energy secondary electrons are abundantly produced in astrophysical or planetary ices by the numerous ionizing radiation fields typically encountered in space environments and may thus play a role in the radiation processing of such ices [1]. One approach to determine their chemical effect is to irradiate nanometer thick molecular solids of simple molecular constituents, with energy selected electron beams and to monitor changes in film chemistry with the surface analytical techniques [2].Of particular interest is the formation of HCN, which is a signature of dense gases in interstellar clouds, and is ubiquitous in the ISM. Moreover, the chemistry of HCN radiolysis products such as CN- may be essential to understand of the formation of amino acids [3] and purine DNA bases. Here we present new results on the irradiation of multilayer films of CO2 and NH3 with 70 eV electrons, leading to CN bond formations. The electron stimulated desorption (ESD) yields of cations and anions are recorded as a function of electron fluence. The prompt desorption of cationic reaction/scattering products [4], is observed at low fluence (~4x1013 electrons/cm2). Detected ions include C2+, C2O2+, C2O+, CO3+, C2O3+ or CO4+ from pure CO2, and N+, NH+, NH2+, NH3+, NH4+, N2+, N2H+ from pure NH3, and NO+, NOH+ from CO2/NH3 mixtures. Most saliently, increasing signals of negative ion products desorbing during prolonged irradiation of CO2/NH3 films included C2-, C2H-, C2H2-, as well as CN-, HCN- and H2CN-. The identification of particular product ions was accomplished by using 13CO2 and 15NH3 isotopes. The chemistry induced by electrons in pure films of CO2 and NH3 and mixtures with composition ratios (3:1), (1:1), and (1:3), was also studied by X-ray photoelectron spectroscopy (XPS). Irradiation of CO2/NH3 mixed films at 22 K produces species containing the following bonds/functional groups identified by XPS: C=O, O-H, C-C, C-O, C=N and N=O. (This work has been funded by NSERC).

Total scattering cross-sections for the systems nH2 + nH2, pH2 + pH2, nD2 + nD2, oD2 + oD2 and HD + HD for relative energies below ten milli-electron volts

International Nuclear Information System (INIS)

Johnson, D.L.

1979-01-01

Relative total scattering cross sections for nH 2 + nH 2 , pH 2 + pH 2 , nD 2 + nD 2 , oD 2 + oD 2 , and HD + HD were measured with inclined nozzle beams derived from nozzle sources and intersecting at 21 0 . Both nozzles could be varied in temperature from 4.2K to 300K to provide the velocity range for the cross sections. The use of a parahydrogen converter allowed the measurement of the pH 2 + pH 2 and oD 2 + oD 2 cross sections. Cross sections for the H 2 + H 2 were measured over a relative velocity range of 200 m/s to 1450 m/s. The nH 2 + nH 2 results show an undulation in the velocity range between 350 m/s and 400 m/s that corresponds to a l = 3 orbiting resonance. Analysis of the pH 2 + pH 2 cross section indicates a l = 4 orbiting resonance near 586 m/s. This resonance has a peak energy of 1.79 meV and a measured energy width of 1.05 meV, both which agree well with theoretical predictions. The D 2 + D 2 cross sections have been measured in the velocity range between 190 m/s and 1000 m/s. No orbiting resonances have been observed, but in the oD 2 + oD 2 cross section a deep minimum between the l = 4 and the l = 5 resonances at low velocities is clearly suggested. Initial measurements of the HD + HD cross section suggests the presence of the l = 4 orbiting resonance near a relative velocity of 300 m/s. The experimental results for each system were normalized to the total cross sections, which were convoluted to account for experimental velocity and angular dispersions. Three different potentials were considered, but a chi-square fit of the data indicates that the Schaefer and Meyer potential, which has been theoretically obtained from first principles, provides the best overall description of the hydrogen systems in the low collisional energy range

[KDy(Hptc3(H3ptc]n·2n(Hbipy·5n(H2O, a Layered Coordination Polymer Containing DyO6N3 Tri-Capped Trigonal Prisms (H3ptc = Pyridine 2,4,6-Tricarboxylic Acid, C8H5NO6; Bipy = 2,2'-Bipyridine, C10H8N2

Directory of Open Access Journals (Sweden)

Shoaib Anwar

2012-08-01

Full Text Available The synthesis, structure and properties of the bimetallic layered coordination polymer, [KDy(C8H3NO63(C8H5NO6]n·2n(C10H9N2·5n(H2O = [KDy(Hptc3(H3ptc]n·2n(Hbipy·5n(H2O, are described. The Dy3+ ion is coordinated by three O,N,O-tridentate doubly-deprotonated pyridine tri-carboxylate (Hptc ligands to generate a fairly regular DyO6N3 tri-capped trigonal prism, with the N atoms acting as the caps. The potassium ion is coordinated by an O,N,O-tridentate H3ptc molecule as well as monodentate and bidentate Hptc ligands to result in an irregular KNO9 coordination geometry. The ligands bridge the metal-atom nodes into a bimetallic, layered, coordination polymer, which extends as corrugated layers in the (010 plane, with the mono-protonated bipyridine cations and water molecules occupying the inter-layer regions: Unlike related structures, there are no dysprosium–water bonds. Many O–HLO and N–HLO hydrogen bonds consolidate the structure. Characterization and bioactivity data are described. Crystal data: C52H42DyKN8O29, Mr = 1444.54, triclinic,  (No. 2, Z = 2, a = 9.188(2 Å, b = 15.7332(17 Å, c = 19.1664(19 Å, α = 92.797(6°, β = 92.319(7°, γ = 91.273(9°, V = 2764.3(7 Å3, R(F = 0.029, wR(F2 = 0.084.

Theoretical study on the spectroscopic properties of CO3(*-).nH2O clusters: extrapolation to bulk.

Science.gov (United States)

Pathak, Arup K; Mukherjee, Tulsi; Maity, Dilip K

2008-10-24

Vertical detachment energies (VDE) and UV/Vis absorption spectra of hydrated carbonate radical anion clusters, CO(3)(*-).nH(2)O (n=1-8), are determined by means of ab initio electronic structure theory. The VDE values of the hydrated clusters are calculated with second-order Moller-Plesset perturbation (MP2) and coupled cluster theory using the 6-311++G(d,p) set of basis functions. The bulk VDE value of an aqueous carbonate radical anion solution is predicted to be 10.6 eV from the calculated weighted average VDE values of the CO(3)(*-).nH(2)O clusters. UV/Vis absorption spectra of the hydrated clusters are calculated by means of time-dependent density functional theory using the Becke three-parameter nonlocal exchange and the Lee-Yang-Parr nonlocal correlation functional (B3LYP). The simulated UV/Vis spectrum of the CO(3)(*-).8H(2)O cluster is in excellent agreement with the reported experimental spectrum for CO(3)(*-) (aq), obtained based on pulse radiolysis experiments.

Physical Properties of (NH4)2Pt(CN)4[Clo.42].3H2O: A new Quasi-One-Dimensional Conductor

DEFF Research Database (Denmark)

Carneiro, Kim; Petersen, A. S.; Underhill, A. E.

1979-01-01

The quasi-one-dimensional conductor (NH4)2[Pt(CN)4]Cl0.42·3H2O, ACP(Cl), has been studied experimentally by means of electrical conduction measurements, x-ray diffuse scattering, and neutron inelastic scattering. This allows the determination of all the physical parameters of interest for the the......The quasi-one-dimensional conductor (NH4)2[Pt(CN)4]Cl0.42·3H2O, ACP(Cl), has been studied experimentally by means of electrical conduction measurements, x-ray diffuse scattering, and neutron inelastic scattering. This allows the determination of all the physical parameters of interest...

Volumetric and viscometric properties of binary and ternary mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate, monoethanolamine and water

International Nuclear Information System (INIS)

Yin, Yaran; Zhu, Chunying; Ma, Youguang

2016-01-01

Highlights: • Densities and viscosities of [Bmim][BF 4 ] + MEA + H 2 O solutions were measured. • Volumetric and viscometric properties were deduced from experimental results. • Intermolecular interactions were analysed by volumetric and viscometric properties. - Abstract: Densities and viscosities of binary {[Bmim][BF 4 ] + H 2 O}, {[Bmim][BF 4 ] + MEA}, (MEA + H 2 O) and ternary mixtures {[Bmim][BF 4 ] + MEA + H 2 O} were measured at T = (293.15–333.15) K. The volumetric and viscometric properties, such as excess molar volume V E , viscosity deviation Δη, and excess Gibbs energy of activation of viscous flow ΔG ∗E for all mixtures, and apparent molar volume, excess partial molar volume and Grunberg-Nissan interaction parameter G 12 for binary mixtures, were deduced from experimental results, and the intermolecular interactions in solutions were also analysed. The excess molar volumes were correlated using the Redlich-Kister polynomial equation for binary mixtures, and Singh et al. equation for the ternary mixture with corresponding binary parameters. The viscosities of binary and ternary solutions were respectively fitted by Jouyban-Acree equation and its extended equation at each measurement temperature, the correlated values are in good agreement with the corresponding experimental data.

Enhanced CO2 capture in binary mixtures of 1-alkyl-3-methylimidazolium tricyanomethanide ionic liquids with water.

Science.gov (United States)

Romanos, George E; Zubeir, Lawien F; Likodimos, Vlassis; Falaras, Polycarpos; Kroon, Maaike C; Iliev, Boyan; Adamova, Gabriela; Schubert, Thomas J S

2013-10-10

Absorption of carbon dioxide and water in 1-butyl-3-methylimidazoliun tricyanomethanide ([C4C1im][TCM]) and 1-octyl-3-methylimidazolium tricyanomethanide ([C8C1im][TCM]) ionic liquids (ILs) was systematically investigated for the first time as a function of the H2O content by means of a gravimetric system together with in-situ Raman spectroscopy, excess molar volume (V(E)), and viscosity deviation measurements. Although CO2 absorption was marginally affected by water at low H2O molar fractions for both ILs, an increase of the H2O content resulted in a marked enhancement of both the CO2 solubility (ca. 4-fold) and diffusivity (ca. 10-fold) in the binary [C(n)C1im][TCM]/H2O systems, in contrast to the weak and/or detrimental influence of water in most physically and chemically CO2-absorbing ILs. In-situ Raman spectroscopy on the IL/CO2 systems verified that CO2 is physically absorbed in the dry ILs with no significant effect on their structural organization. A pronounced variation of distinct tricyanomethanide Raman modes was disclosed in the [C(n)C1im][TCM]/H2O mixtures, attesting to the gradual disruption of the anion-cation coupling by the hydrogen-bonded water molecules to the [TCM](-) anions, in accordance with the positive excess molar volumes and negative viscosity deviations for the binary systems. Most importantly, CO2 absorption in the ILs/H2O mixtures at high water concentrations revealed that the [TCM](-) Raman modes tend to restore their original state for the heavily hydrated ILs, in qualitative agreement with the intriguing nonmonotonous transients of CO2 absorption kinetics unveiled by the gravimetric measurements for the hybrid solvents. A molecular exchange mechanism between CO2 in the gas phase and H2O in the liquid phase was thereby proposed to explain the enhanced CO2 absorption in the hybrid [C(n)C1im][TCM]//H2O solvents based on the subtle competition between the TCM-H2O and TCM-CO2 interactions, which renders these ILs very promising for CO2

Synthesis and properties of ternary (K, NH4, H3O)-jarosites precipitated from Acidithiobacillus ferrooxidans cultures in simulated bioleaching solutions

International Nuclear Information System (INIS)

Sandy Jones, F.; Bigham, Jerry M.; Gramp, Jonathan P.; Tuovinen, Olli H.

2014-01-01

The purpose of this study was to synthesize a series of solid solution jarosites by biological oxidation of ferrous iron at pH 2.2–4.4 and ambient temperature in media containing mixtures of K + (0, 1, 4, 6, 12, 31 mM) and NH 4 + (6.1, 80, 160, 320 mM). The starting material was a liquid medium for Acidithiobacillus ferrooxidans comprised of 120 mM FeSO 4 solution and mineral salts at pH 2.2. Following inoculation with A. ferrooxidans, the cultures were incubated in shake flasks at 22 °C. As bacteria oxidized ferrous iron, ferric iron hydrolyzed and precipitated as jarosite-group minerals (AFe 3 (SO 4 ) 2 (OH) 6 ) and/or schwertmannite (idealized formula Fe 8 O 8 (OH) 6 (SO 4 )·nH 2 O). The precipitates were characterized by X-ray diffraction (XRD), elemental analysis, and Munsell color. Schwertmannite was the dominant mineral product at low combinations of K + (≤ 4 mM) and NH 4 + (≤ 80 mM) in the media. At higher single or combined concentrations, yellowish jarosite phases were produced, and Munsell hue provided a sensitive means of detecting minor schwertmannite in the oxidation products. Although the hydrated ionic radii of K + and NH 4 + are similar, K + greatly facilitated the formation of a jarosite phase compared to NH 4 + . Unit cell and cell volume calculations from refinements of the powder XRD patterns indicated that the jarosite phases produced were mostly ternary (K, NH 4 , H 3 O)-solid solutions that were also deficient in structural Fe, especially at low NH 4 contents. Thus, ferric iron precipitation from the simulated bioleaching systems yielded solid solutions of jarosite with chemical compositions that were dependent on the relative concentrations of K + and NH 4 + in the synthesis media. No phase separations involving discrete, end-member K-jarosite or NH 4 -jarosite were detected in the un-aged precipitates. - Highlights: • Fe(III) precipitates formed in A. ferrooxidans culture solutions were characterized. • The monovalent cation

Crystal structure of [UO2(NH35]NO3·NH3

Directory of Open Access Journals (Sweden)

Patrick Woidy

2016-12-01

Full Text Available Pentaammine dioxide uranium(V nitrate ammonia (1/1, [UO2(NH35]NO3·NH3, was obtained in the form of yellow crystals from the reaction of caesium uranyl nitrate, Cs[UO2(NO33], and uranium tetrafluoride, UF4, in dry liquid ammonia. The [UO2]+ cation is coordinated by five ammine ligands. The resulting [UO2(NH35] coordination polyhedron is best described as a pentagonal bipyramid with the O atoms forming the apices. In the crystal, numerous N—H...N and N—H...O hydrogen bonds are present between the cation, anion and solvent molecules, leading to a three-dimensional network.

NMR Spectroscopic Characterization of Methylcobalt(III) Compounds with Classical Ligands. Crystal Structures of [Co(NH(3))(5)(CH(3))]S(2)O(6), trans-[Co(en)(2)(NH(3))(CH(3))]S(2)O(6) (en = 1,2-Ethanediamine), and [Co(NH(3))(6)]-mer,trans-[Co(NO(2))(3)(NH(

DEFF Research Database (Denmark)

Kofod, Pauli; Harris, Pernille; Larsen, Sine

1997-01-01

magnetic resonance spectroscopy and by absorption spectroscopy. Single-crystal X-ray structure determinations at 122.0(5) K were performed on [Co(NH(3))(5)(CH(3))]S(2)O(6) (1), trans-[Co(en)(2)(NH(3))(CH(3))]S(2)O(6) (2), and [Co(NH(3))(6)]-mer,trans-[Co(NO(2))(3)(NH(3))(2)(CH(3))](2)-trans-[Co(NO(2...

Graphene assisted effective hole-extraction on In2O3:H/CH3NH3PbI3 interface: Studied by modulated surface spectroscopy

Science.gov (United States)

Vinoth Kumar, Sri Hari Bharath; Muydinov, Ruslan; Kol'tsova, Tat‘yana; Erfurt, Darja; Steigert, Alexander; Tolochko, Oleg; Szyszka, Bernd

2018-01-01

Charge separation in CH3NH3PbI3 (MAPbI3) films deposited on a hydrogen doped indium oxide (In2O3:H) photoelectrode was investigated by modulated surface photovoltage (SPV) spectroscopy in a fixed capacitor arrangement. It was found that In2O3:H reproducibly extracts photogenerated-holes from MAPbI3 films. The oxygen-plasma treatment of the In2O3:H surface is suggested to be a reason for this phenomenon. Introducing graphene interlayer increased charge separation nearly 6 times as compared to that on the In2O3:H/MAPbI3 interface. Furthermore, it is confirmed by SPV spectroscopy that the defects of the MAPbI3 interface are passivated by graphene.

Preparation, Characterization, and Structure of Two Layered Molybdenum(VI) Phosphates: KMo(H 2O)O 2PO 4 and NH 4Mo(H 2O)O 2PO 4

Science.gov (United States)

Millini, Roberto; Carati, Angela

1995-08-01

New layered Mo(VI) compounds, KMo(H 2O)O 2PO 4 (I) and NH 4Mo(H 2O)O 2PO 4 (II), were synthesized hydrothermally and their structures were determined from single-crystal X-ray analysis. Compounds (I) and (II) are isostructural and crystallize in the monoclinic P2 1/ n space group with a = 12.353(3), b = 8.623(2), c = 5.841(1) Å, β = 102.78(1)°, V = 606.8(2) Å 3, Z = 4, and R = 0.027 ( Rw = 0.030) for compound (I) and a = 12.435(3), b = 8.761(2), c = 6.015(1), β = 103.45(1)°, V = 637.3(2) Å 3, Z = 4, and R = 0.040 ( Rw = 0.041) for compound (II). The structure consists of layers built up of eight- and four-membered rings resulting from the alternation of corner-sharing [MoO 6] octahedra and [PO 4] tetrahedra. The layers stack along the (1¯01) direction by intercalating K and NH 4 ions.

Interactive effects of MnO2, organic matter and pH on abiotic formation of N2O from hydroxylamine in artificial soil mixtures

Science.gov (United States)

Liu, Shurong; Berns, Anne E.; Vereecken, Harry; Wu, Di; Brüggemann, Nicolas

2017-02-01

Abiotic conversion of the reactive nitrification intermediate hydroxylamine (NH2OH) to nitrous oxide (N2O) is a possible mechanism of N2O formation during nitrification. Previous research has demonstrated that manganese dioxide (MnO2) and organic matter (OM) content of soil as well as soil pH are important control variables of N2O formation in the soil. But until now, their combined effect on abiotic N2O formation from NH2OH has not been quantified. Here, we present results from a full-factorial experiment with artificial soil mixtures at five different levels of pH, MnO2 and OM, respectively, and quantified the interactive effects of the three variables on the NH2OH-to-N2O conversion ratio (RNH2OH-to-N2O). Furthermore, the effect of OM quality on RNH2OH-to-N2O was determined by the addition of four different organic materials with different C/N ratios to the artificial soil mixtures. The experiments revealed a strong interactive effect of soil pH, MnO2 and OM on RNH2OH-to-N2O. In general, increasing MnO2 and decreasing pH increased RNH2OH-to-N2O, while increasing OM content was associated with a decrease in RNH2OH-to-N2O. Organic matter quality also affected RNH2OH-to-N2O. However, this effect was not a function of C/N ratio, but was rather related to differences in the dominating functional groups between the different organic materials.

Kinetics of struvite to newberyite transformation in the precipitation system MgCl2-NH4H2PO4NaOH-H2O.

Science.gov (United States)

Babić-Ivancić, Vesna; Kontrec, Jasminka; Brecević, Ljerka; Kralj, Damir

2006-10-01

The influence of the initial reactant concentrations on the composition of the solid phases formed in the precipitation system MgCl(2)-NH(4)H(2)PO(4)-NaOH-H(2)O was investigated. The precipitation diagram constructed shows the approximate concentration regions within which struvite, newberyite, and their mixtures exist at 25 degrees C and an aging time of 60 min. It was found that immediately after mixing the reactant solutions, struvite (MgNH(4)PO(4).6H(2)O) precipitated in nearly the whole concentration area, while newberyite (MgHPO(4).3H(2)O) appeared mostly within the region of the excess of magnesium concentration. It was also found that after aging time of 60 min the precipitation domain of struvite alone is much broader than that of newberyite or the domain of their coexistence, and shows that struvite is more abundant in the systems in which the initial concentration of ammonium phosphate is higher than that of magnesium. The kinetics of struvite to newberyite transformation (conversion) was systematically studied under the conditions of different initial reactant concentrations and different initial pH in the systems in which a mixture of both phases precipitated spontaneously. The struvite to newberyite conversion period was found to be strongly related to the ratio of initial supersaturations, S(N)/S(S), rather than to the any particular physical quantity that can describe and predict the behavior of the precipitation system. Experimental data suggest a solution-mediated process as a most possible transformation mechanism. Along with a continuous monitoring of the changes in the liquid phase, the content of struvite in the solid phase was estimated by means of a Fourier transform infrared (FT-IR) method, developed for this particular precipitation system.

Modeling impacts of NH{sub 3} on uptake of H{sub 2}SO{sub 4} by charged nucleating nanoparticles in the Earth's atmosphere

Energy Technology Data Exchange (ETDEWEB)

Nadykto, A. B., E-mail: anadykto@gmail.com [Atmospheric Science Research Center, State University of New York at Albany, 251 Fuller Road, Albany, NY 12203 (United States); Department of Applied Mathematics, Moscow State University of Technology “STANKIN”, Vadkovsky per. 1, Moscow 127055 (Russian Federation); Nazarenko, K. M.; Markov, P. N. [Department of Applied Mathematics, Moscow State University of Technology “STANKIN”, Vadkovsky per. 1, Moscow 127055 (Russian Federation); Yu, F. [Atmospheric Science Research Center, State University of New York at Albany, 251 Fuller Road, Albany, NY 12203 (United States)

2016-06-08

The understanding of the role of ammonia, a well-known stabilizer of binary sulfuric acid-water clusters, in the gas-to-nanoparticle conversion in the Earth atmosphere is critically important for the assessment of aerosol radiative forcing associated with the climate changes. The sulfuric acid H{sub 2}SO{sub 4} is present in the atmosphere in the form of the gas-phase hydrates (H{sub 2}SO{sub 4})(H{sub 2}O){sub n}, whose interaction with NH{sub 3} leads to the formation of more stable bisulfate clusters (NH{sub 3})(H{sub 2}SO{sub 4})(H{sub 2}O){sub n}. Although the impact of NH{sub 3} on the thermochemical stability of binary clusters nucleating homogeneously has been studied in some detail in the past, the effect of ammonia on other microphysical properties relevant to nucleation remains insufficiently well understood. In the present study, the effect of ammonia on the electrical dipole moment controlling the nucleation of airborne ions via the dipole-charge interaction has been investigated using the Density Functional Theory (DFT), ab initio MP2 and model chemistry G3 methods. The presence of ammonia in (H{sub 2}SO{sub 4})(H{sub 2}O){sub n} is found to lead to very large enhancement in the dipole moment, which exceeds 2.0-2.5 Debyes (∼60-80%), 3.7-5.0 Debyes (∼90-180%), 1.4-4.5 Debyes (∼50-150%) and 2.1-5.5 Debyes (∼60-700%) for n = 0, n = 1, n = 2 and n = 3, respectively. The implications of this include the significantly increased uptake of the sulfuric acid, the key atmospheric nucleation precursor, by airborne ions and neutrals (due to dipole-dipole interaction), enhanced nucleation rates and the elevated production of ultrafine particles, which cause adverse health impacts.

Development and Application of Binary Suspensions in the Ternary System Cr2O3-TiO2-Al2O3 for S-HVOF Spraying

Science.gov (United States)

Potthoff, Annegret; Kratzsch, Robert; Barbosa, Maria; Kulissa, Nick; Kunze, Oliver; Toma, Filofteia-Laura

2018-04-01

Compositions in the system Cr2O3-TiO2-Al2O3 are among the most used ceramic materials for thermally sprayed coating solutions. Cr2O3 coatings present good sliding wear resistance; Al2O3 coatings show excellent insulation behavior and TiO2 striking corrosion properties. In order to combine these properties, coatings containing more than one oxide are highly interesting. The conventional spraying process is limited to the availability of binary feedstock powders with defined compositions. The use of suspensions offers the opportunity for tailor-made chemical compositions: within the triangle of Cr2O3-TiO2-Al2O3, each mixture of oxides can be created. Criteria for the selection of raw materials as well as the relevant aspects for the development of binary suspensions in the Cr2O3-TiO2-Al2O3 system to be used as feedstock for thermal spraying are presented. This formulation of binary suspensions required the development of water-based single-oxide suspensions with suitable behavior; otherwise, the interaction between the particles while mixing could lead up to a formation of agglomerates, which affect both the stability of the spray process and the coating properties. For the validation of this formulation procedure, binary Cr2O3-TiO2 and Al2O3-TiO2 suspensions were developed and sprayed using the S-HVOF process. The binary coatings were characterized and discussed in terms of microstructure and microhardness.

Development and Application of Binary Suspensions in the Ternary System Cr2O3-TiO2-Al2O3 for S-HVOF Spraying

Science.gov (United States)

Potthoff, Annegret; Kratzsch, Robert; Barbosa, Maria; Kulissa, Nick; Kunze, Oliver; Toma, Filofteia-Laura

2018-03-01

Compositions in the system Cr2O3-TiO2-Al2O3 are among the most used ceramic materials for thermally sprayed coating solutions. Cr2O3 coatings present good sliding wear resistance; Al2O3 coatings show excellent insulation behavior and TiO2 striking corrosion properties. In order to combine these properties, coatings containing more than one oxide are highly interesting. The conventional spraying process is limited to the availability of binary feedstock powders with defined compositions. The use of suspensions offers the opportunity for tailor-made chemical compositions: within the triangle of Cr2O3-TiO2-Al2O3, each mixture of oxides can be created. Criteria for the selection of raw materials as well as the relevant aspects for the development of binary suspensions in the Cr2O3-TiO2-Al2O3 system to be used as feedstock for thermal spraying are presented. This formulation of binary suspensions required the development of water-based single-oxide suspensions with suitable behavior; otherwise, the interaction between the particles while mixing could lead up to a formation of agglomerates, which affect both the stability of the spray process and the coating properties. For the validation of this formulation procedure, binary Cr2O3-TiO2 and Al2O3-TiO2 suspensions were developed and sprayed using the S-HVOF process. The binary coatings were characterized and discussed in terms of microstructure and microhardness.

Synthesis and characteristics of a novel 3-D organic amine oxalate: (enH2)1.5[Bi3(C2O4)6(CO2CONHCH2CH2NH3)].6.5H2O

International Nuclear Information System (INIS)

Yu Xiaohong; Zhang Hanhui; Cao Yanning; Chen Yiping; Wang Zhen

2006-01-01

A novel 3-D compound of (enH 2 ) 1.5 [Bi 3 (C 2 O 4 ) 6 (CO 2 CONHCH 2 CH 2 NH 3 )].6.5H 2 O has been hydrothermally synthesized and characterized by IR, ultraviolet-visible diffuse reflection integral spectrum (UV-Vis DRIS), fluorescence spectra, TGA and single crystal X-ray diffraction. It crystallizes in the monoclinic system, space group C2/c with a=31.110(8)A, b=11.544(3)A, c=22.583(6)A, β=112.419(3) o , V=7497(3)A 3 , Z=8, R 1 =0.0463 and wR 2 =0.1393 for unique 7686 reflections I>2σ(I). In the title compound, the Bi atoms have eight-fold and nine-fold coordination with respect to the oxygen atoms, with the Bi atoms in distorted dodecahedron and monocapped square antiprism, respectively. The 3-D framework of the title compound contains channels and is composed of linkages between Bi atoms and oxalate units, forming honeycomb-like layers with two kinds of 6+6 membered aperture, and pillared by oxalate ligands and monamide groups. The channels have N-ethylamine oxalate monamide group - CO 2 CONHCH 2 CH 2 NH 3 + , which is formed by the in situ reaction of en and oxalate acid. At room temperature, the complex exhibits intense blue luminescence with an emission peak at 445nm

Magnetic susceptibility and specific heat of the one-dimensional conductor (H3O) sub (1,6) Pt (C2O4)2.nH2O at low temperatures

International Nuclear Information System (INIS)

Raede, H.S.

1985-01-01

It has been shown recently that some transition metal complexes exhibit one-dimensional metallic properties. It is reported, in this context, susceptibility and specific heat measurements of polycrystalline (H 3 O) 1 , 6 Pt(C 2 O 4 ) 2 .nH 2 O in the low temperature range. It is found that the susceptibility can be described by a non-uniform Curie law with a characteristic break in the slope. The specific heat reveals no linear temperature contribution, which could be explained by a transition into a Peierls distorted state. Until 13 0 K, the heat capacity follows a T 3 -law. Deviations at higher temperatures are possibly attributed to the anisotropy of the system [pt

Dehydriding reaction of Mg(NH2)2-LiH system under hydrogen pressure

International Nuclear Information System (INIS)

Aoki, M.; Noritake, T.; Kitahara, G.; Nakamori, Y.; Towata, S.; Orimo, S.

2007-01-01

The dehydriding and structural properties of the 3Mg(NH 2 ) 2 + 12LiH system under hydrogen pressure were investigated using the pressure-composition (p-c) isotherm measurement and X-ray diffraction (XRD) analysis. Two distinct regions, a plateau region and a sloping region, can be seen on the p-c isotherms and the amount of the desorbed hydrogen at 523 K was 4.9 mass%. The enthalpy of hydrogenation calculated using a van't Hoff plot was -46 kJ/mol H 2 . The dehydriding reaction was proposed for the 3Mg(NH 2 ) 2 + 12LiH system based on the obtained p-c isotherms and XRD profiles and chemical valences of Li, Mg, N, and H. In the plateau region on the p-c isotherm, Mg(NH 2 ) 2 , Li 4 Mg 3 (NH 2 ) 2 (NH) 4 (tetragonal), and LiH phases coexist and the molar ratio of the Li 4 Mg 3 (NH 2 ) 2 (NH) 4 phase increases (while those of Mg(NH 2 ) 2 and LiH phases decrease) with the amount of the desorbed hydrogen. On the other hand, the mixture of Li 4+x Mg 3 (NH 2 ) 2-x (NH) 4+x + (8-x)LiH (0 ≤ x ≤ 2) is formed and the lattice volume of the Li 4+x Mg 3 (NH 2 ) 2-x (NH) 4+x phase continuously increases with the amount of the desorbed hydrogen in the sloping region on the p-c isotherm

Removal of binary dyes mixtures with opposite and similar charges by adsorption, coagulation/flocculation and catalytic oxidation in the presence of CeO2/H2O2 Fenton-like system.

Science.gov (United States)

Issa Hamoud, Houeida; Finqueneisel, Gisèle; Azambre, Bruno

2017-06-15

In this study, the removal of binary mixtures of dyes with similar (Orange II/Acid Green 25) or opposite charges (Orange II/Malachite Green) was investigated either by simple adsorption on ceria or by the heterogeneous Fenton reaction in presence of H 2 O 2 . First, the CeO 2 nanocatalyst with high specific surface area (269 m 2 /g) and small crystal size (5 nm) was characterized using XRD, Raman spectroscopy and N 2 physisorption at 77 K. The adsorption of single dyes was studied either from thermodynamic and kinetic viewpoints. It is shown that the adsorption of dyes on ceria surface is highly pH-dependent and followed a pseudo-second order kinetic model. Adsorption isotherms fit well the Langmuir model with a complete monolayer coverage and higher affinity towards Orange II at pH 3, compared to other dyes. For the (Orange II/Acid Green 25) mixture, both the amounts of dyes adsorbed on ceria surface and discoloration rates measured from Fenton experiments were decreased by comparison with single dyes. This is due to the adsorption competition existing onto the same surface Ce x+ sites and the reaction competition with hydroxyl radicals, respectively. The behavior of the (Orange II/Malachite Green) mixture is markedly different. Dyes with opposite charges undergo paired adsorption on ceria as well as homogeneous and heterogeneous coagulation/flocculation processes, but can also be removed by heterogeneous Fenton process. Copyright © 2016 Elsevier Ltd. All rights reserved.

MeB5O8(Me-Li, Na, K, NH4)-H2NCONHCOCH3-H2O system at 25 deg C

International Nuclear Information System (INIS)

Skvortsov, V.G.; Fedorov, Yu.A.; Molodkin, A.K.; Tsekhanskij, R.S.

1986-01-01

Using the methods of isothermal solubility, densi- and refractometry, systems MB 5 O 8 (M-Li, Na, K, NH 4 )-acetylcarbamide - H 2 O at 25 deg C have been studied. It is ascertained, that the systems investigated are of simple eutonic type

Thermal and x-ray crystallographic features of the binary system UO2(NO3)2.6H2O-Ni(NO3)2.6H2O at elevated temperatures

International Nuclear Information System (INIS)

Kalekar, B.B.; Rajagopalan, K.V.; Ravindran, P.V.

2007-01-01

Solid state reaction between uranyl nitrate hexahydrate and nickel nitrate hexahydrate of different compositions has been studied at higher temperatures. The binary system containing uranyl nitrate hexahydrate (UNH) and nickel nitrate hexahydrate is found to form eutectic corresponding to 53 mol% of uranyl nitrate hexahydrate at 40 degC. The overlap of evolution of nitric oxide and water vapour above 230 degC confirmed the presence of hydroxynitrates of uranium and nickel. Both the nitrates decomposed independently. NiO formed by the decomposition of nickel nitrate hexahydrate reacted with UO 3 formed by the initial decomposition of uranyl nitrate hexahydrate to form a double oxide, NiU 3 O 10 , in the case of mixtures containing 70 mol% uranyl nitrate hexahydrate. The compositions richer than 70 mol% in uranyl nitrate hexahydrate formed U 3 O 8 along with nickel uranate. With mixtures leaner in uranyl nitrate hexahydrate, NiO was observed along with NiU 3 O 10 and, further, the formation of NiU 3 O 10 was completed at a lower temperature. (author)

Synthesis and crystal structure of 4-fluorobenzylammonium dihydrogen phosphate, [FC6H4CH2NH3]H2PO4

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Ali Rayes

2016-12-01

Full Text Available The asymmetric unit of the title salt, [p-FC6H4CH2NH3]+·H2PO4−, contains one 4-fluorobenzylammonium cation and one dihydrogen phosphate anion. In the crystal, the H2PO4− anions are linked by O—H...O hydrogen bonds to build corrugated layers extending parallel to the ab plane. The FC6H4CH2NH3+ cations lie between these anionic layers to maximize the electrostatic interactions and are linked to the H2PO4− anions through N—H...O hydrogen bonds, forming a three-dimensional supramolecular network. Two hydrogen atoms belonging to the dihydrogen phosphate anion are statistically occupied due to disorder along the OH...HO direction.

Sonolytic Oxidation of Tc(IVO2nH2O Nanoparticles to Tc(VIIO4 in Aqueous Solution

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M. Zakir

2010-04-01

Full Text Available Sonolysis of a hydrosol of TcO2nH2O was investigated in the Ar- or He- atmosphere. Colloidal TcO2nH2O nanoparticles were irradiated with a 200 kHz and 1.25 W/cm2 ultrasound. It was found that the TcO2nH2O colloids dispersed in an aqueous solution (under Ar or He atmosphere was completely dissolved by ultrasonic irradiation (200 kHz, 200 W. The original brownish black color of the suspension slowly disappeared leaving behind a colorless solution. This change suggests that oxidation of Tc(IV to Tc(VII takes place. The oxidation was almost complete during 30 minutes sonication time under argon atmosphere for initial concentration of 6.0E-5 M. Addition of t-butyl alcohol, an effective radical scavenger which readily reacts with OH radicals, supressed the dissolution of TcO2nH2O colloids. This reaction indicates that TcO2nH2O molecules are oxidized by OH radicals produced in cavitation bubbles.

The loss of NH2O from the N-hydroxyacetamide radical cation CH3C(O)NHOH+

Science.gov (United States)

Jobst, Karl J.; Burgers, Peter C.; Ruttink, Paul J. A.; Terlouw, Johan K.

2006-08-01

A previous study [Ch. Lifshitz, P.J.A. Ruttink, G. Schaftenaar, J.K. Terlouw, Rapid Commun. Mass Spectrom. 1 (1987) 61] shows that metastable N-hydroxyacetamide ions CH3C(O)NHOH+ (HA-1) do not dissociate into CH3CO+ + NHOH by direct bond cleavage but rather yield CH3CO+ + NH2OE The tandem mass spectrometry based experiments of the present study on the isotopologue CH3C(O)NDOD+ reveal that the majority of the metastable ions lose the NH2O radical as NHDO rather than ND2O. A mechanistic analysis using the CBS-QB3 model chemistry shows that the molecular ions HA-1 rearrange into hydrogen-bridged radical cations [OCC(H2)H...N(H)OH]+ whose acetyl cation component then catalyses the transformation NHOH --> NH2O prior to dissociation. The high barrier for the unassisted 1,2-H shift in the free radical, 43 kcal mol-1, is reduced to a mere 7 kcal mol-1 for the catalysed transformation which can be viewed as a quid-pro-quo reaction involving two proton transfers.

Photocrystallographic structure determination of a new geometric isomer of [Ru(NH3)4(H2O)(eta1-OSO)][MeC6H4SO3]2.

Science.gov (United States)

Bowes, Katharine F; Cole, Jacqueline M; Husheer, Shamus L G; Raithby, Paul R; Savarese, Teresa L; Sparkes, Hazel A; Teat, Simon J; Warren, John E

2006-06-21

The structure of a new metastable geometric isomer of [Ru(NH3)4(H2O)(SO2)][MeC6H4SO3]2 in which the SO2 group is coordinated through a single oxygen in an eta1-OSO bonding mode has been determined at 13 K; the new isomer was obtained as a 36% component of the structure within a single crystal upon irradiation using a tungsten lamp.

NH4(+) Resides Inside the Water 20-mer Cage As Opposed to H3O(+), Which Resides on the Surface: A First Principles Molecular Dynamics Simulation Study.

Science.gov (United States)

Willow, Soohaeng Yoo; Singh, N Jiten; Kim, Kwang S

2011-11-08

Experimental vibrational predissociation spectra of the magic NH4(+)(H2O)20 clusters are close to those of the magic H3O(+)(H2O)20 clusters. It has been assumed that the geometric features of NH4(+)(H2O)20 clusters might be close to those of H3O(+)(H2O)20 clusters, in which H3O(+) resides on the surface. Car-Parrinello molecular dynamics simulations in conjunction with density functional theory calculations are performed to generate the infrared spectra of the magic NH4(+)(H2O)20 clusters. In comparison with the experimental vibrational predissociation spectra of NH4(+)(H2O)20, we find that NH4(+) is inside the cage structure of NH4(+)(H2O)20 as opposed to on the surface structure. This shows a clear distinction between the structures of NH4(+)(H2O)20 and H3O(+)(H2O)20 as well as between the hydration phenomena of NH4(+) and H3O(+).

C-H and C-C activation of n -butane with zirconium hydrides supported on SBA15 containing N-donor ligands: [(≡SiNH-)(≡SiX-)ZrH2], [(≡SiNH-)(≡SiX-)2ZrH], and[(≡SiN=)(≡SiX-)ZrH] (X = -NH-, -O-). A DFT study

KAUST Repository

Pasha, Farhan Ahmad; Bendjeriou-Sedjerari, Anissa; Huang, Kuo-Wei; Basset, Jean-Marie

2014-01-01

: [(≡SiNH-)(≡SiO-)ZrH2] (A), [(≡SiNH-)2ZrH2] (B), [(≡SiNH-)(≡SiO-) 2ZrH] (C), [(≡SiNH-)2(≡SiO-)ZrH] (D), [(≡SiN=)(≡Si-O-)ZrH] (E), and [(≡SiN=)(≡SiNH-)ZrH] (F). The roles of these hydrides have been investigated in C-H/C-C bond activation and cleavage

[H3N(CH2)4NH3]2[Al4(C2O4)(H2PO4)2(PO4)4].4[H2O]: A new layered aluminum phosphate-oxalate

International Nuclear Information System (INIS)

Peng Li; Li Jiyang; Yu Jihong; Li Guanghua; Fang Qianrong; Xu Ruren

2005-01-01

A new layered inorganic-organic hybrid aluminum phosphate-oxalate [H 3 N(CH 2 ) 4 NH 3 ] 2 [Al 4 (C 2 O 4 )(H 2 PO 4 ) 2 (PO 4 ) 4 ].4[H 2 O](AlPO-CJ25) has been synthesized hydrothermally, by using 1,4-diaminobutane (DAB) as structure-directing agent. The structure has been solved by single-crystal X-ray diffraction analysis and further characterized by IR, 31 P MAS NMR, TG-DTA as well as compositional analyses. Crystal data: the triclinic space group P-1, a=8.0484(7) A, b=8.8608(8) A, c=13.2224(11) A, α=80.830(6) deg. , β=74.965(5) deg. , γ=78.782(6) deg. , Z=2, R 1[ I >2 σ ( I )] =0.0511 and wR 2(alldata) =0.1423. The alternation of AlO 4 tetrahedra and PO 4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO 6 octahedra to form the layered structure with 4,6-net sheet. Interestingly, oxalate ions are bis-bidentately bonded by participating in the coordination of AlO 6 , and bridging the adjacent AlO 6 octahedra. The layers are held with each other through strong H-bondings between the terminal oxygens. The organic ammonium cations and water molecules are located in the large cavities between the interlayer regions. -- Graphical abstract: The alternation of AlO 4 tetrahedra and PO 4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO 6 octahedra to form the layered structure with 4,6-net sheet. Oxalate ions are bis-bidentately boned by participating in the coordination of AlO 6 , and bridging the adjacent AlO 6 octahedra

Synthesis and properties of ternary (K, NH{sub 4}, H{sub 3}O)-jarosites precipitated from Acidithiobacillus ferrooxidans cultures in simulated bioleaching solutions

Energy Technology Data Exchange (ETDEWEB)

Sandy Jones, F.; Bigham, Jerry M. [School of Environment and Natural Resources, Ohio State University, 2021 Coffey Road, Columbus, OH 43210 (United States); Gramp, Jonathan P. [Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210 (United States); Tuovinen, Olli H., E-mail: tuovinen.1@osu.edu [Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210 (United States)

2014-11-01

The purpose of this study was to synthesize a series of solid solution jarosites by biological oxidation of ferrous iron at pH 2.2–4.4 and ambient temperature in media containing mixtures of K{sup +} (0, 1, 4, 6, 12, 31 mM) and NH{sub 4}{sup +} (6.1, 80, 160, 320 mM). The starting material was a liquid medium for Acidithiobacillus ferrooxidans comprised of 120 mM FeSO{sub 4} solution and mineral salts at pH 2.2. Following inoculation with A. ferrooxidans, the cultures were incubated in shake flasks at 22 °C. As bacteria oxidized ferrous iron, ferric iron hydrolyzed and precipitated as jarosite-group minerals (AFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}) and/or schwertmannite (idealized formula Fe{sub 8}O{sub 8}(OH){sub 6}(SO{sub 4})·nH{sub 2}O). The precipitates were characterized by X-ray diffraction (XRD), elemental analysis, and Munsell color. Schwertmannite was the dominant mineral product at low combinations of K{sup +} (≤ 4 mM) and NH{sub 4}{sup +} (≤ 80 mM) in the media. At higher single or combined concentrations, yellowish jarosite phases were produced, and Munsell hue provided a sensitive means of detecting minor schwertmannite in the oxidation products. Although the hydrated ionic radii of K{sup +} and NH{sub 4}{sup +} are similar, K{sup +} greatly facilitated the formation of a jarosite phase compared to NH{sub 4}{sup +}. Unit cell and cell volume calculations from refinements of the powder XRD patterns indicated that the jarosite phases produced were mostly ternary (K, NH{sub 4}, H{sub 3}O)-solid solutions that were also deficient in structural Fe, especially at low NH{sub 4} contents. Thus, ferric iron precipitation from the simulated bioleaching systems yielded solid solutions of jarosite with chemical compositions that were dependent on the relative concentrations of K{sup +} and NH{sub 4}{sup +} in the synthesis media. No phase separations involving discrete, end-member K-jarosite or NH{sub 4}-jarosite were detected in the un-aged precipitates

Experimental studies of the formation of cluster ions formed by corona discharge in an atmosphere containing SO₂, NH₃, and H₂O

DEFF Research Database (Denmark)

Hvelplund, Preben; Pedersen, Jens Olaf Pepke; Støchkel, Kristian

2013-01-01

Abstract We report on studies of ion-induced nucleation in a corona discharge taking place in an atmosphere containing SO2, NH3, and H2O at standard temperature and pressure. Positive ions such as H3O+(H2O)n, NH4+(H2O)n, and H+(H2SO4)(H2O)n and negative ions such as HSO5-(H2O)n, SO4-(H2O)n, HSO4-(H......5-, which has been observed in many studies, in our experiments is contaminated by O2-(HNO3)(H2O) ions, and this may also have been the case in other experiments. Finally an ion with m/z = 232 (where m is the cluster mass in amu and z is the charge state), capable of attaching H2O...

Catalysts for selective hydrogenation of furfural derived from the double complex salt [Pd(NH 3 ) 4 ](ReO 4 ) 2 on γ-Al 2 O 3

Energy Technology Data Exchange (ETDEWEB)

Thompson, Simon T.; Lamb, H. Henry

2017-06-01

The double complex salt [Pd(NH3)4](ReO4)2 was employed as precursor of supported bimetallic catalysts for selective hydrogenation of furfural. Direct reduction of [Pd(NH3)4](ReO4)2 on γ-Al2O3 in flowing H2 at 400 °C yields bimetallic nanoparticles 1–2 nm in size that exhibit significant interaction between the metals, as evidenced by temperature-programmed hydride decomposition (complete suppression of β-PdHx formation), extended X-ray absorption fine structure spectroscopy at the Pd K and Re LIII edges (PdRe distance = 2.72 Å), and scanning transmission electron microscopy with energy dispersive X-ray analysis. In contrast, calcination of [Pd(NH3)4](ReO4)2 on γ-Al2O3 at 350 °C in air and subsequent reduction in H2 at 400 °C results in metal segregation and formation of large (>50 nm) supported Pd particles; Re species cover the Pd particles and γ-Al2O3 support. A PdRe 1:2 catalyst prepared by sequential impregnation and calcination using HReO4 and [Pd(NH3)4](NO3)2 has a similar morphology. The catalyst derived by direct reduction of [Pd(NH3)4](ReO4)2 on γ-Al2O3 exhibits remarkably high activity for selective hydrogenation of furfural to furfuryl alcohol (FAL) at 150 °C and 1 atm. Suppression of H2 chemisorption via elimination of Pd threefold sites, as evidenced by CO diffuse-reflectance infrared Fourier transform spectroscopy, correlates with increased FAL selectivity.

The effect of pressure on the conductivity behavior of the (NH4)3H(SeO4)2 superprotonic crystal

Science.gov (United States)

Lindner, Ł.; Zdanowska-Frączek, M.; Pawłowski, A.; Frączek, Z. J.; Masłowski, T.

2017-07-01

The impedance spectra of (NH4)3 H(SeO4)2 in low and high-conductive phases under various thermodynamic conditions were analyzed. The measurements were performed by the ac admittance technique along the trigonal c axis of the crystal, i.e., along the direction perpendicular to the plane in which, in the superionic phases, a dynamically disordered H-bond network was formed. Activation energies and activation volumes were calculated for different phases of the (NH4)3 H(SeO4)2 crystal from the baric dependencies of dc conductivity and they were correlated with pressure coefficients of the phase transitions. The experimental results were analyzed within the classical hopping model, in terms of the strong proton-phonon coupling and polaronic effect.

Conductance Studies on Complex Formation between c-Methylcalix[4]resorcinarene and Titanium (III in Acetonitrile-H2O Binary Solutions

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Naghmeh Saadati

2013-09-01

Full Text Available Calixresorcinarenes have proved to be unique molecules for molecular recognition via hydrogen bonding, hydrophobic and ionic interactions with suitable substrates such as cations. The study of the interactions involved in the complexation of different cations with calixresorcinarenes in solvent mixtures is important for a better understanding of the mechanism of biological transport, molecular recognition, and other analytical applications. This article summarizes different aspects of the complexes of the Ti3+ metal cation with c-methylcalix[4]resorcinarene (CMCR as studied by conductometry in acetonitrile (AN–water (H2O binary mixtures at different temperatures. Conductance data show that the metal cation/ligand (ML stoichiometry of the complexes in solution is 1:1 in all cases. Non-linear behaviour was observed for the variation of logKf of the complexes vs. the composition of the binary solvent mixtures. Selectivity of CMCR for the Ti3+ cation is sensitive to solvent composition; in some cases and at certain compositions of the mixed solvent systems, the selectivity order is changed. Values of thermodynamic parameters (, for formation of the CMCR–Ti3+ complexes in AN–H2O binary systems were obtained from the temperature dependence of stability constants, and the results show that the thermodynamics of complexation reactions are affected by the nature and composition of the mixed solvents.

[Ag(NH3)2]Ag(OsO3N)2: a new nitridoosmate(VIII)

International Nuclear Information System (INIS)

Wickleder, M.S.; Pley, Martin

2004-01-01

Dark brown single crystals of [Ag(NH 3 ) 2 ]Ag(OsO 3 N) 2 were obtained from the reaction of Ag 2 CO 3 , OsO 4 , and NH 3 in aqueous solution. The crystal structure was solved in the monoclinic space group C2/m, with the following unit-cell dimensions: a=1962.5(3), b=633.1(1), c=812.6(1) pm, β=96.71(1) deg. The final reliability factor was R=0.0256 for 1034 reflections with I>2σ(I). Linear [Ag(NH 3 ) 2 ] + ions are present oriented perpendicular to the [010] direction, leading to short Ag + -Ag + distances of 316 pm. A second type of Ag + ions in the crystal structure present coordination number '6+1' and are surrounded by oxygen and nitrogen atoms of the nitridoosmate groups. Within the first of the two crystallographically distinguishable anions one can clearly differentiate between oxygen and nitrogen atoms while the second one exhibits a N/O disorder over two positions. The infrared spectrum of [Ag(NH 3 ) 2 ]Ag(OsO 3 N) 2 shows the typical absorptions which can be attributed to the complex anions and the NH 3 ligands

Improved Dehydrogenation Properties of 2LiNH2-MgH2 by Doping with Li3AlH6

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Shujun Qiu

2017-01-01

Full Text Available Doping with additives in a Li-Mg-N-H system has been regarded as one of the most effective methods of improving hydrogen storage properties. In this paper, we prepared Li3AlH6 and evaluated its effect on the dehydrogenation properties of 2LiNH2-MgH2. Our studies show that doping with Li3AlH6 could effectively lower the dehydrogenation temperatures and increase the hydrogen content of 2LiNH2-MgH2. For example, 2LiNH2-MgH2-0.1Li3AlH6 can desorb 6.43 wt % of hydrogen upon heating to 300 °C, with the onset dehydrogenation temperature at 78 °C. Isothermal dehydrogenation testing indicated that 2LiNH2-MgH2-0.1Li3AlH6 had superior dehydrogenation kinetics at low temperature. Moreover, the release of byproduct NH3 was successfully suppressed. Measurement of the thermal diffusivity suggests that the enhanced dehydrogenation properties may be ascribed to the fact that doping with Li3AlH6 could improve the heat transfer for solid–solid reaction.

Crystal structure of NH4[La(SO42(H2O

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Meriem Benslimane

2015-06-01

Full Text Available The principal building units in the crystal structure of ammonium aquabis(sulfatolanthanate(III are slightly distorted SO4 tetrahedra, LaO9 polyhedra in the form of distorted tricapped trigonal prisms, and NH4+ ions. The La3+ cation is coordinated by eight O atoms from six different sulfate tetrahedra, two of which are bidentate coordinating and four monodentate, as well as one O atom from a water molecule; each sulfate anion bridges three La3+ cations. These bridging modes result in the formation of a three-dimensional anionic [La(SO42(H2O]− framework that is stabilized by O—H...O hydrogen-bonding interactions. The disordered ammonium cations are situated in the cavities of this framework and are hydrogen-bonded to six surrounding O atoms.

Dynamic investigation of the diffusion absorption refrigeration system NH3-H2O-H2

Directory of Open Access Journals (Sweden)

Mohamed Izzedine Serge Adjibade

2017-09-01

Full Text Available This paper reports on a numerical and experimental study of a diffusion absorption refrigerator. The performance of the system is examined by computer simulation using MATLAB software and Engineering Equations Solver. A dynamic model is developed for each component of the system and solved numerically in order to predict the transient state of the diffusion absorption refrigeration. The experiment set included 0.04 m3 commercial absorption diffusion refrigerator working with the ammonia-water-hydrogen (NH3-H2O-H2 solution. The transient numerical results were validated with the experimental data. The investigations are focused on the dynamic profile of the temperature of each component. The results obtained agree with the experiment; the relative error between numerical and experimental models doesn’t exceed 15% for all temperatures of each component. The increase of the average ambient temperature from 23.04 °C to 32.56 °C causes an increase of the condensation temperature from 29.46 °C to 37.51 °C, and the best evaporation temperature obtained was 3 °C, with an ambient temperature of 23.04 °C. The results show that a minimum starting temperature of 152 °C and 63.8 W electric power are required to initiate the decrease of evaporation temperature.

H2 dilution effect in the Cat-CVD processes of the SiH4/NH3 system

International Nuclear Information System (INIS)

Ansari, S.G.; Umemoto, Hironobu; Morimoto, Takashi; Yoneyama, Koji; Izumi, Akira; Masuda, Atsushi; Matsumura, Hideki

2006-01-01

Gas-phase diagnostics in the catalytic chemical vapor deposition processes of the SiH 4 /NH 3 /H 2 system were carried out to examine the effect of H 2 dilution. The decomposition efficiency of NH 3 showed a sharp decrease with the introduction of a small amount of SiH 4 , but this decrease was recovered by the addition of H 2 when the NH 3 pressure was low. On the other hand, at higher NH 3 pressures, the decomposition efficiency showed a minor dependence on the H 2 partial pressure. The addition of SiH 4 to the NH 3 system decreases the H-atom density by one order of magnitude, but this decrease is also recovered by H 2 addition. H atoms produced from H 2 must re-activate the catalyzer surfaces poisoned by SiH 4 when the NH 3 pressure is low

Synthesis of Cu3N from CuO and NaNH2

Directory of Open Access Journals (Sweden)

Akira Miura

2014-12-01

Full Text Available We report on the low-temperature synthesis of submicron-sized Cu3N powder produced from CuO and NaNH2 powder mixture by heating at 150–190 °C in a Teflon-sealed autoclave. The structure was the anti-RuO3 type with a lattice parameter of 0.3814(1 nm, and strong optical absorption was observed below ∼1.9 eV. This synthesis method has the potential of facile control of the reaction with less use of ammonia sources.

Synthesis, characterization and electrochemical performance of graphene decorated with 1D NiMoO4.nH2O nanorods

Science.gov (United States)

Ghosh, Debasis; Giri, Soumen; Das, Chapal Kumar

2013-10-01

based composite, which exhibited a high specific capacitance of 367 F g-1 at 5 A g-1 current density and a high energy density of 10.32 W h kg-1 at a power density of 1125 W kg-1 accompanied with long term cyclic stability. Electronic supplementary information (ESI) available: Materials used, characterization techniques and preparation of electrode, tables containing specific capacitance, coulombic efficiency, energy density and power density values at different current densities of NiMoO4.nH2O and Gr-NiMoO4.nH2O. See DOI: 10.1039/c3nr02444j

Transfer of π- from hydrogen to deuterium in H2O + D2O mixtures

International Nuclear Information System (INIS)

Stanislaus, S.; Measday, D.F.; Vetterli, D.; Weber, P.; Aniol, K.A.; Harston, M.R.; Armstrong, D.S.

1989-07-01

The transfer of stopping π - mesons from hydrogen to deuterium has been investigated in mixtures of H 2 O+D 2 O as a function of D 2 O concentration. The concentration dependence of the transfer probability is similar to that observed for the gas mixtures of H 2 and D 2 but slightly more transfer is found for H 2 O+D 2 O. (Author) 17 refs., 2 tabs., 4 figs

[Pr2(pdc3(Hpdc(H2O4]n·n(H3hp·8n(H2O, a One-Dimensional Coordination Polymer Containing PrO6N3 Tri-Capped Trigonal Prisms and PrO8N Mono-Capped Square Anti-Prisms (H2pdc = Pyridine 2,6-Dicarboxylic Acid, C7H5NO4; 3hp = 3-Hydroxy Pyridine, C5H5NO

Directory of Open Access Journals (Sweden)

Shahzad Sharif

2012-08-01

Full Text Available The synthesis, structure and some properties of the one-dimensional coordination polymer, [Pr2(pdc3(Hpdc]n·n(H3hp·8n(H2O, (H2pdc = pyridine 2,6-dicarboxylic acid, C7H5NO4; 3hp = 3-hydroxypyridine, C5H5NO are described. One of the Pr3+ ions is coordinated by two O,N,O-tridentate pdc2− ligands and one tridentate Hpdc− anion to generate a fairly regular PrO6N3 tri-capped trigonal prism, with the N atoms acting as the caps. The second Pr3+ ion is coordinated by one tridentate pdc2− dianion, four water molecules and two monodentate bridging pdc2− ligands to result in a PrO8N coordination polyhedron that approximates to a mono-capped square-anti-prism. The ligands bridge the metal-atom nodes into a chain, which extends in the [100] direction. The H3hp+ cation and uncoordinated water molecules occupy the inter-chain regions and an N–HLO and numerous O–HLO hydrogen bonds consolidate the structure. The H3hp+ species appears to intercalate between pendant pdc rings to consolidate the polymeric structure. Crystal data: 1 (C33H43N5O29Pr2, Mr = 1255.54, triclinic,  (No. 2, Z = 2, a = 13.2567(1 Å, b = 13.6304(2 Å, c = 13.6409(2 Å, α = 89.695(1°, β = 63.049(1°, γ = 86.105(1°, V = 2191.16(5 Å3, R(F = 0.033, wR(F2 = 0.084.

Glycine formation in CO2:CH4:NH3 ices induced by 0-70 eV electrons

Science.gov (United States)

Esmaili, Sasan; Bass, Andrew D.; Cloutier, Pierre; Sanche, Léon; Huels, Michael A.

2018-04-01

Glycine (Gly), the simplest amino-acid building-block of proteins, has been identified on icy dust grains in the interstellar medium, icy comets, and ice covered meteorites. These astrophysical ices contain simple molecules (e.g., CO2, H2O, CH4, HCN, and NH3) and are exposed to complex radiation fields, e.g., UV, γ, or X-rays, stellar/solar wind particles, or cosmic rays. While much current effort is focused on understanding the radiochemistry induced in these ices by high energy radiation, the effects of the abundant secondary low energy electrons (LEEs) it produces have been mostly assumed rather than studied. Here we present the results for the exposure of multilayer CO2:CH4:NH3 ice mixtures to 0-70 eV electrons under simulated astrophysical conditions. Mass selected temperature programmed desorption (TPD) of our electron irradiated films reveals multiple products, most notably intact glycine, which is supported by control measurements of both irradiated or un-irradiated binary mixture films, and un-irradiated CO2:CH4:NH3 ices spiked with Gly. The threshold of Gly formation by LEEs is near 9 eV, while the TPD analysis of Gly film growth allows us to determine the "quantum" yield for 70 eV electrons to be about 0.004 Gly per incident electron. Our results show that simple amino acids can be formed directly from simple molecular ingredients, none of which possess preformed C—C or C—N bonds, by the copious secondary LEEs that are generated by ionizing radiation in astrophysical ices.

In situ attenuated total reflection infrared (ATR-IR) study of the adsorption of NO2-, NH2OH, and NH4+ on Pd/Al2O3 and Pt/Al2O3.

NARCIS (Netherlands)

Ebbesen, S.D.; Mojet, Barbara; Lefferts, Leonardus

2008-01-01

In relation to the heterogeneous hydrogenation of nitrite, adsorption of NO2-, NH4+, and NH2OH from the aqueous phase was examined on Pt/Al2O3, Pd/Al2O3, and Al2O3. None of the investigated inorganic nitrogen compounds adsorb on alumina at conditions presented in this study. NO2-(aq) and NH4+(aq) on

Electron spin resonance study of a-Cr2O3 and Cr2O3·nH2O quasi-spherical nanoparticles

CSIR Research Space (South Africa)

Khamlich, S

2011-12-01

Full Text Available The quasi-spherical nanoparticles of hydrated Cr2O3 · nH2O, and crystalline -Cr2O3, have been synthesized by reduction of the first row (3d) transition metal complex of K2Cr2O7. The temperaturedependence of electron spin resonance (ESR) spectrum...

Experimental Study on Optimization of Absorber Configuration in Compression/Absorption Heat Pump with NH{sub 3}/H{sub 2}O Mixture

Energy Technology Data Exchange (ETDEWEB)

Kim, Ji Young; Kim, Min Sung; Baik, Young Jin; Park, Seong Ryong; Chang, Ki Chang; Ra, Ho Sang [Korea Institute of Energy Research, Daejeon (Korea, Republic of); Kim, Yong Chan [Korea University, Seoul (Korea, Republic of)

2011-03-15

This research aims to develop a compression/absorption hybrid heat pump system using an NH{sub 3}/H{sub 2}O as working fluid. The heat pump cycle is based on a combination of compression and absorption cycles. The cycle consists of two-stage compressors, absorbers, a de superheater, solution heat exchangers, a solution pump, a rectifier, and a liquid/vapor separator. The compression/absorption hybrid heat pump was designed to produce hot water above 90 .deg. C using high-temperature glide during a two-phase heat transfer. Distinct characteristics of the nonlinear temperature profile should be considered to maximize the performance of the absorber. In this study, the performance of the absorber was investigated depending on the capacity, shape, and arrangement of the plate heat exchangers with regard to the concentration and distribution at the inlet of the absorber.

Energetics of fragmentation of CH5, H3O, and NH4 from neutralized ion-beam experiments

International Nuclear Information System (INIS)

Williams, B.W.; Porter, R.F.

1980-01-01

Fragmentation energies for radicals of the type RH 2 (RH=CH 4 , NH 3 , and H 2 O) produced by electron capture interactions of 5 keV RH 2 + ion with Na or K atoms are reported. The experimental technique involves measurement of spatial beam profiles resulting from dissociation of neutral radicals following their formation in a near resonant electron transfer process. Cross sections for RH 2 + --Na capture reactions are typically 1x10 -14 cm 2 . Fragmentation energies from measurements with Na target atoms are -2.65 +- 0.14, -0.22 +- 0.03, and -1.12 +- 0.07 eV for CH 5 , NH 4 , and H 3 O, respectively. From our results with Na and K targets and published values for proton affinities, the vertical electron affinities of CH 5 + and H 3 O + are calculated to be 5.3 +- 0.2 eV and 5.1 +- 0.3 eV, respectively. Beam profiles for ND 4 show this species to be metastable with a lifetime of about 1 μs. From this we estimate a potential barrier to dissociation in NH 4 (ND 4 ) between 0.36 and 0.48 eV, indicating this species should be stable at low temperatures. Comparison of these experimental results with theoretical calculations indicates areas of disagreement

Reference value standards and primary standards for pH measurements in D2O and aqueous-organic solvent mixtures: new accessions and assessments

International Nuclear Information System (INIS)

Mussini, P.R.; Mussini, T.; Rondinini, S.

1997-01-01

Recommended Reference Value Standards based on the potassium hydro-genphthalate buffer at various temperatures are reported for pH measurements in various binary solvent mixtures of water with eight organic solvents: methanol, ethanol, 2-propanol, 1,2-ethanediol, 2-methoxyethanol (''methylcellosolve''), acetonitrile, 1,4-dioxane, and dimethyl sulfoxide, together with Reference Value Standard based on the potassium deuterium phthalate buffer for pD measurements in D 2 O. In addition are reported Primary Standards for pH based on numerous buffers in various binary solvent mixtures of water with methanol, ethanol, and dimethyl sulfoxide, together with Primary Standards for pD in D 2 O based on the citrate, phosphate and carbonate buffers. (author)

Selectivity of Catalytically Modified Tin Dioxide to CO and NH3 Gas Mixtures

Directory of Open Access Journals (Sweden)

Artem Marikutsa

2015-10-01

Full Text Available This paper is aimed at selectivity investigation of gas sensors, based on chemically modified nanocrystalline tin dioxide in the detection of CO and ammonia mixtures in air. Sol-gel prepared tin dioxide was modified by palladium and ruthenium oxides clusters via an impregnation technique. Sensing behavior to CO, NH3 and their mixtures in air was studied by in situ resistance measurements. Using the appropriate match of operating temperatures, it was shown that the reducing gases mixed in a ppm-level with air could be discriminated by the noble metal oxide-modified SnO2. Introducing palladium oxide provided high CO-sensitivity at 25–50 °C. Tin dioxide modified by ruthenium oxide demonstrated increased sensor signals to ammonia at 150–200 °C, and selectivity to NH3 in presence of higher CO concentrations.

Physical limit of stability in supercooled D2O and D2O+H2O mixtures

Science.gov (United States)

Kiselev, S. B.; Ely, J. F.

2003-01-01

The fluctuation theory of homogeneous nucleation was applied for calculating the physical boundary of metastable states, the kinetic spinodal, in supercooled D2O and D2O+H2O mixtures. The kinetic spinodal in our approach is completely determined by the surface tension and equation of state of the supercooled liquid. We developed a crossover equation of state for supercooled D2O, which predicts a second critical point of low density water-high density water equilibrium, CP2, and represents all available experimental data in supercooled D2O within experimental accuracy. Using Turnbull's expression for the surface tension we calculated with the crossover equation of state for supercooled D2O the kinetic spinodal, TKS, which lies below the homogeneous nucleation temperature, TH. We show that CP2 always lies inside in the so-called "nonthermodynamic habitat" and physically does not exist. However, the concept of a second "virtual" critical point is physical and very useful. Using this concept we have extended this approach to supercooled D2O+H2O mixtures. As an example, we consider here an equimolar D2O+H2O mixture in normal and supercooled states at atmospheric pressure, P=0.1 MPa.

Radiolysis of nitrite, bromate and permanganate ions and their binary mixtures in aqueous solutions at pH 10

International Nuclear Information System (INIS)

Dedgaonkar, V.G.; Kulkarni, S.A.; Mahajan, C.T.

1981-01-01

#betta#-radiolysis of pure systems viz. nitrite, bromate and permanganate and their binary mixtures (MNO 4- /NO 2- , MnO 4- /BrO 3- ) in aqueous solution at pH 10 is studied as a function of dose and concentration. In pure systems the G(NO 3- ), G(Br - ) and G(-MnO 4- ) increase with increasing concentration. The first two show an identical limiting value of approximately 0.5 while the last increases from 0.68 below 10 4 M and reaches 2.5 at 10 - 2 M concentration. Presence of 10 - 1 M BrO 3- or 10 - 2 M NO 2- reduces the G(-MnO 4- ) from 1.07 for the pure 10 - 3 M permanganate solution to 0.2 and 0.7 respectively. A mechanism based on the competitive kinetics is envisaged to explain the observed results. (author)

Room and high temperature interactions in sodium and rubidium rich ternary nitrate mixtures of UO2(NO3)2.6H2O - NaNO3 - RbNO3

International Nuclear Information System (INIS)

Kalekar, Bhupesh B.; Reddy, A.V.R.; Raje, Naina

2016-01-01

High temperature interaction behavior of nitrates is important for characterizing different intermediate products and their thermal stabilities during the calcination of nuclear waste before their immobilization in the stable glass matrix. Mixtures of UO 2 (NO 3 ) 2 .6H 2 O (UNH) with NaNO 3 (NaN) and RbNO 3 (RbN) were prepared by mixing the weighed amounts of component nitrates and grinding gently in a mortar and pestle. The mixing and grinding of individual nitrate components in a mortar with pestle showed the agglomeration of solid particles and subsequent dissolution probably in the water of crystallization of UNH. The continued grinding and mixing showed the reappearance of the solid powder. The original yellow color of the mixture was changed to greenish yellow color. The mixtures were subjected to thermal measurements using Netzsch Thermobalance (Model No.: STA 409 PC Luxx) coupled to Bruker FTIR system (Model No.: Tensor 27) via a heated Teflon capillary (1 m long, 2 mm i.d.). TG - DTG curves of equimolar mixture are displayed. The plateau was observed on TG curve in the temperature region of 31- 250 °C. It is reported that Na(UO 2 (NO 3 ) 3 ).H 2 O and Rb(UO 2 (NO 3 ) 3 ) formed around 250 °C in the equimolar nitrate mixtures of UNH-NaN and UNH-RbN. Thermal and XRD results indicated the formation of Na(UO 2 (NO 3 ) 3 ).H 2 O and Rb(UO 2 (NO) 3 ) 3 ) even by mixing the UNH, NaN and RbN in equimolar ratios at room temperature

Rate-based modelling of combined SO2 removal and NH3 recycling integrated with an aqueous NH3-based CO2 capture process

International Nuclear Information System (INIS)

Li, Kangkang; Yu, Hai; Qi, Guojie; Feron, Paul; Tade, Moses; Yu, Jingwen; Wang, Shujuan

2015-01-01

Highlights: • A rigorous, rate-based model for an NH 3 –CO 2 –SO 2 –H 2 O system was developed. • Model predictions are in good agreement with pilot plant results. • >99.9% of SO 2 was captured and >99.9% of slipped ammonia was reused. • The process is highly adaptable to the variations of SO 2 /NH 3 level, temperatures. - Abstract: To reduce the costs of controlling emissions from coal-fired power stations, we propose an advanced and effective process of combined SO 2 removal and NH 3 recycling, which can be integrated with the aqueous NH 3 -based CO 2 capture process to simultaneously achieve SO 2 and CO 2 removal, NH 3 recycling and flue gas cooling in one process. A rigorous, rate-based model for an NH 3 –CO 2 –SO 2 –H 2 O system was developed and used to simulate the proposed process. The model was thermodynamically and kinetically validated by experimental results from the open literature and pilot-plant trials, respectively. Under typical flue gas conditions, the proposed process has SO 2 removal and NH 3 reuse efficiencies of >99.9%. The process is strongly adaptable to different scenarios such as high SO 2 levels in flue gas, high NH 3 levels from the CO 2 absorber and high flue gas temperatures, and has a low energy requirement. Because the process simplifies flue gas desulphurisation and resolves the problems of NH 3 loss and SO 2 removal, it could significantly reduce the cost of CO 2 and SO 2 capture by aqueous NH 3

Molecular modelling of the decomposition of NH{sub 3} over CoO(100)

Energy Technology Data Exchange (ETDEWEB)

Shojaee, Kambiz; Haynes, Brian S.; Montoya, Alejandro, E-mail: alejandro.montoya@sydney.edu.au

2015-04-15

Spin-polarised density functional theory using the PBE + U approach are used to determine reaction pathways of successive NH{sub 3} dehydrogenation on the CoO(100) surface. NH{sub 3} dehydrogenation promotes noticeable displacements of the surface CoO sites, in particular due to the binding of NH{sub 2} and H species. Surface lattice O has low activity towards dehydrogenation, reflected in energy barriers that are in the range of 292 kJ mol{sup −1} to 328 kJ mol{sup −1}. There is a preference of surface NH{sub 3} dehydrogenation to N{sub 2} rather than towards NO, due to a high-energy penalty of surface O vacancy formation. The presence of CoO in cobalt oxide catalysts not only may decline the ammonia conversion but also alter the selectivity towards N{sub 2} rather than NO. - Highlights: • Minimum reactions pathways of ammonia decomposition were studied using density functional theory. • The bonding characteristics of NH{sub x} and H on the CoO(100) surface were analysed using Layer-projected density of states. • Dehydrogenations of NH{sub 3}, NH{sub 2} and NH are highly activated. • The presence of strongly bound lattice oxygen favours the ammonia decomposition towards N{sub 2}.

Mesoscopic CH 3 NH 3 PbI 3 /TiO 2 Heterojunction Solar Cells

KAUST Repository

Etgar, Lioz

2012-10-24

We report for the first time on a hole conductor-free mesoscopic methylammonium lead iodide (CH 3NH 3PbI 3) perovskite/TiO 2 heterojunction solar cell, produced by deposition of perovskite nanoparticles from a solution of CH 3NH 3I and PbI 2 in γ-butyrolactone on a 400 nm thick film of TiO 2 (anatase) nanosheets exposing (001) facets. A gold film was evaporated on top of the CH 3NH 3PbI 3 as a back contact. Importantly, the CH 3NH 3PbI 3 nanoparticles assume here simultaneously the roles of both light harvester and hole conductor, rendering superfluous the use of an additional hole transporting material. The simple mesoscopic CH 3NH 3PbI 3/TiO 2 heterojunction solar cell shows impressive photovoltaic performance, with short-circuit photocurrent J sc= 16.1 mA/cm 2, open-circuit photovoltage V oc = 0.631 V, and a fill factor FF = 0.57, corresponding to a light to electric power conversion efficiency (PCE) of 5.5% under standard AM 1.5 solar light of 1000 W/m 2 intensity. At a lower light intensity of 100W/m 2, a PCE of 7.3% was measured. The advent of such simple solution-processed mesoscopic heterojunction solar cells paves the way to realize low-cost, high-efficiency solar cells. © 2012 American Chemical Society.

Semiconducting perovskites (2-XC6H4C2H4NH3)2SnI4 (X = F, Cl, Br): steric interaction between the organic and inorganic layers.

Science.gov (United States)

Xu, Zhengtao; Mitzi, David B; Dimitrakopoulos, Christos D; Maxcy, Karen R

2003-03-24

Two new semiconducting hybrid perovskites based on 2-substituted phenethylammonium cations, (2-XC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) (X = Br, Cl), are characterized and compared with the previously reported X = F compound, with a focus on the steric interaction between the organic and inorganic components. The crystal structure of (2-ClC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) is solved in a disordered subcell [C2/m, a = 33.781(7) A, b = 6.178(1) A, c = 6.190(1) A, beta = 90.42(3)(o), and Z = 2]. The structure is similar to the known (2-FC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) structure with regard to both the conformation of the organic cations and the bonding features of the inorganic sheet. The (2-BrC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) system adopts a fully ordered monoclinic cell [P2(1)/c, a = 18.540(2) A, b = 8.3443(7) A, c = 8.7795(7) A, beta = 93.039(1)(o), and Z = 2]. The organic cation adopts the anti conformation, instead of the gauche conformation observed in the X = F and Cl compounds, apparently because of the need to accommodate the additional volume of the bromo group. The steric effect of the bromo group also impacts the perovskite sheet, causing notable distortions, such as a compressed Sn-I-Sn bond angle (148.7(o), as compared with the average values of 153.3 and 154.8(o) for the fluoro and chloro compounds, respectively). The optical absorption features a substantial blue shift (lowest exciton peak: 557 nm, 2.23 eV) relative to the spectra of the fluoro and chloro compounds (588 and 586 nm, respectively). Also presented are transport properties for thin-film field-effect transistors (TFTs) based on spin-coated films of the two hybrid semiconductors.

1H and 2H NMR relaxation study on the phase transitions of (NH4)3H(SO4)2 and (ND4)3D(SO4)2 single crystals

International Nuclear Information System (INIS)

Lim, Ae Ran; Jeong, Se-Young

2006-01-01

T 1 , T 1ρ and T 2 for the 1 H and 2 H nuclei in (NH 4 ) 3 H(SO 4 ) 2 and (ND 4 ) 3 D(SO 4 ) 2 single crystals grown using the slow evaporation method were measured for phases I, II, III, IV and V. The 1 H T 1 , T 1ρ , and T 2 values were found to exhibit different trends in phases II and III: T 1 , T 1ρ and T 2 for 1 H do not change significantly near the phase transition at 265 K, whereas near 413 K they change discontinuously. We conclude that the NH 4 + and H(SO 4 ) 2 - ions do not play an important role in the III-II phase transition, but do play important roles in the II-I phase transition. The liquid-like nature of the 1 H T 1ρ and T 2 above 413 K is indicative of the destruction and reconstruction of hydrogen bonds. Moreover, the phase transitions of the (NH 4 ) 3 H(SO 4 ) 2 crystal are accompanied by changes in the molecular motion of the (NH 4 ) + ions. The variations with temperature of the 2 H T 1 and T 2 of (ND 4 ) 3 D(SO 4 ) 2 crystals are not similar to those observed for the 1 H T 1 and T 2 . Our comparison of the results for (NH 4 ) 3 H(SO 4 ) 2 and (ND 4 ) 3 D(SO 4 ) 2 crystals indicates the following: the 1 H T 1ρ and T 2 of the (NH 4 ) + and H(SO 4 ) 2 - ions above T C1 are characteristic of fast, liquid-like motion, which is not the case for (ND 4 ) 3 D(SO 4 ) 2 ; and the 2 H T 1 of D(SO 4 ) 2 - in (ND 4 ) 3 D(SO 4 ) 2 is longer than the 2 H T 1 of (ND 4 ) + in contrast to the results for (NH 4 ) 3 H(SO 4 ) 2 crystals

C-H and C-C activation of n -butane with zirconium hydrides supported on SBA15 containing N-donor ligands: [(≡SiNH-)(≡SiX-)ZrH2], [(≡SiNH-)(≡SiX-)2ZrH], and[(≡SiN=)(≡SiX-)ZrH] (X = -NH-, -O-). A DFT study

KAUST Repository

Pasha, Farhan Ahmad

2014-07-01

Density functional theory (DFT) was used to elucidate the mechanism of n-butane hydrogenolysis (into propane, ethane, and methane) on well-defined zirconium hydrides supported on SBA15 coordinated to the surface via N-donor surface pincer ligands: [(≡SiNH-)(≡SiO-)ZrH2] (A), [(≡SiNH-)2ZrH2] (B), [(≡SiNH-)(≡SiO-) 2ZrH] (C), [(≡SiNH-)2(≡SiO-)ZrH] (D), [(≡SiN=)(≡Si-O-)ZrH] (E), and [(≡SiN=)(≡SiNH-)ZrH] (F). The roles of these hydrides have been investigated in C-H/C-C bond activation and cleavage. The dihydride A linked via a chelating [N,O] surface ligand was found to be more active than B, linked to the chelating [N,N] surface ligand. Moreover, the dihydride zirconium complexes are also more active than their corresponding monohydrides C-F. The C-C cleavage step occurs preferentially via β-alkyl transfer, which is the rate-limiting step in the alkane hydrogenolysis. The energetics of the comparative pathways over the potential energy surface diagram (PES) reveals the hydrogenolysis of n-butane into propane and ethane. © 2014 American Chemical Society.

Mixed adenine/guanine quartets with three trans-a2 Pt(II) (a=NH(3) or MeNH(2)) cross-links: linkage and rotational isomerism, base pairing, and loss of NH(3).

Science.gov (United States)

Albertí, Francisca M; Rodríguez-Santiago, Luis; Sodupe, Mariona; Mirats, Andrea; Kaitsiotou, Helena; Sanz Miguel, Pablo J; Lippert, Bernhard

2014-03-17

Of the numerous ways in which two adenine and two guanines (N9 positions blocked in each) can be cross-linked by three linear metal moieties such as trans-a2 Pt(II) (with a=NH3 or MeNH2 ) to produce open metalated purine quartets with exclusive metal coordination through N1 and N7 sites, one linkage isomer was studied in detail. The isomer trans,trans,trans-[{Pt(NH3 )2 (N7-9-EtA-N1)2 }{Pt(MeNH2 )2 (N7-9-MeGH)}2 ][(ClO4 )6 ]⋅3H2 O (1) (with 9-EtA=9-ethyladenine and 9-MeGH=9-methylguanine) was crystallized from water and found to adopt a flat Z-shape in the solid state as far as the trinuclear cation is concerned. In the presence of excess 9-MeGH, a meander-like construct, trans,trans,trans-[{Pt(NH3 )2 (N7-9-EtA-N1)2 }{Pt(MeNH2 )2 (N7-9-MeGH)2 }][(ClO4 )6 ]⋅[(9-MeGH)2 ]⋅7 H2 O (2) is formed, in which the two extra 9-MeGH nucleobases are hydrogen bonded to the two terminal platinated guanine ligands of 1. Compound 1, and likewise the analogous complex 1 a (with NH3 ligands only), undergo loss of an ammonia ligand and formation of NH4 (+) when dissolved in [D6 ]DMSO. From the analogy between the behavior of 1 and 1 a it is concluded that a NH3 ligand from the central Pt atom is lost. Addition of 1-methylcytosine (1-MeC) to such a DMSO solution reveals coordination of 1-MeC to the central Pt. In an analogous manner, 9-MeGH can coordinate to the central Pt in [D6 ]DMSO. It is proposed that the proton responsible for formation of NH4 (+) is from one of the exocyclic amino groups of the two adenine bases, and furthermore, that this process is accompanied by a conformational change of the cation from Z-form to U-form. DFT calculations confirm the proposed mechanism and shed light on possible pathways of this process. Calculations show that rotational isomerism is not kinetically hindered and that it would preferably occur previous to the displacement of NH3 by DMSO. This displacement is the most energetically costly step, but it is compensated by the proton

Solid state interaction studies on binary nitrate mixtures of uranyl nitrate hexahydrate and lanthanum nitrate hexahydrate at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Kalekar, Bhupesh; Raje, Naina, E-mail: nraje@barc.gov.in; Reddy, A.V.R.

2017-02-15

Interaction behavior of uranyl nitrate hexahydrate (UNH) and lanthanum nitrate hexahydrate (LaNH) have been investigated on the mixtures in different molar ratios of the two precursors and monitoring the reactions at elevated temperatures with thermoanalytical and X-ray diffraction measurement techniques. During the decomposition of equimolar mixture of LaNH and UNH, formation of lanthanum uranate (U{sub 0.5}La{sub 0.5})O{sub 2}, was seen by the temperature of 500 °C along with lanthanum oxide (La{sub 2}O{sub 3}) and uranium trioxide (UO{sub 3}). By the temperature of 700 °C, the formation of uranium sesquioxide (U{sub 3}O{sub 8}) was observed along with (U{sub 0.5}La{sub 0.5})O{sub 2} as end products in uranium rich mixtures. Lanthanum rich compositions decomposed by the temperature of 700 °C to give (U{sub 0.5}La{sub 0.5})O{sub 2} and La{sub 2}O{sub 3} as end products. - Highlights: • UO{sub 2}(NO{sub 3}){sub 2}.6H{sub 2}O and La(NO{sub 3}){sub 3}.6H{sub 2}O interact through their intermediates. • Formation of (U{sub 0.5}La{sub 0.5})O{sub 2} by 500 °C. • La deficient mixtures decompose to give U{sub 3}O{sub 8} and (U{sub 0.5}La{sub 0.5})O{sub 2} as end products. • La rich mixtures decompose to give La{sub 2}O{sub 3} and (U{sub 0.5}La{sub 0.5})O{sub 2} as end product.

Surface Species and Metal Oxidation State during H2-Assisted NH3-SCR of NOx over Alumina-Supported Silver and Indium

Directory of Open Access Journals (Sweden)

Linda Ström

2018-01-01

Full Text Available Alumina-supported silver and indium catalysts are investigated for the hydrogen-assisted selective catalytic reduction (SCR of NOx with ammonia. Particularly, we focus on the active phase of the catalyst and the formation of surface species, as a function of the gas environment. Diffuse reflectance ultraviolet-visible (UV-vis spectroscopy was used to follow the oxidation state of the silver and indium phases, and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS was used to elucidate the formation of surface species during SCR conditions. In addition, the NOx reduction efficiency of the materials was evaluated using H2-assisted NH3-SCR. The DRIFTS results show that the Ag/Al2O3 sample forms NO-containing surface species during SCR conditions to a higher extent compared to the In/Al2O3 sample. The silver sample also appears to be more reduced by H2 than the indium sample, as revealed by UV-vis spectroscopic experiments. Addition of H2, however, may promote the formation of highly dispersed In2O3 clusters, which previously have been suggested to be important for the SCR reaction. The affinity to adsorb NH3 is confirmed by both temperature programmed desorption (NH3-TPD and in situ DRIFTS to be higher for the In/Al2O3 sample compared to Ag/Al2O3. The strong adsorption of NH3 may inhibit (self-poison the NH3 activation, thereby hindering further reaction over this catalyst, which is also shown by the lower SCR activity compared to Ag/Al2O3.

Enzymatic synthesis of 6-O-glucosyl-poly(3-hydroxyalkanoate) in organic solvents and their binary mixture.

Science.gov (United States)

Gumel, A M; Annuar, M S M; Heidelberg, T

2013-04-01

The effects of organic solvents and their binary mixture in the glucose functionalization of bacterial poly-3-hydroxyalkanoates catalyzed by Lecitase™ Ultra were studied. Equal volume binary mixture of DMSO and chloroform with moderate polarity was more effective for the enzyme catalyzed synthesis of the carbohydrate polymer at ≈38.2 (±0.8)% reactant conversion as compared to the mono-phasic and other binary solvents studied. The apparent reaction rate constant as a function of medium water activity (aw) was observed to increase with increasing solvent polarity, with optimum aw of 0.2, 0.4 and 0.7 (±0.1) observed in hydrophilic DMSO, binary mixture DMSO:isooctane and hydrophobic isooctane, respectively. Molecular sieve loading between 13 to 15gL(-1) (±0.2) and reaction temperature between 40 to 50°C were found optimal. Functionalized PHA polymer showed potential characteristics and biodegradability. Copyright © 2012 Elsevier B.V. All rights reserved.

X-ray and NQR studies of bromoindate(III) complexes. [C2H5NH3]4InBr7, [C(NH2)3]3InBr6, and [H3NCH2C(CH3)2CH2NH3]InBr5

International Nuclear Information System (INIS)

Iwakiri, Takeharu; Ishihara, Hideta; Terao, Hiromitsu; Lork, Enno; Gesing, Thorsten M.

2017-01-01

The crystal structures of [C 2 H 5 NH 3 ] 4 InBr 7 (1), [C(NH 2 ) 3 ] 3 InBr 6 (2), and [H 3 NCH 2 C(CH 3 ) 2 CH 2 NH 3 ]InBr 5 (3) were determined at 100(2) K: monoclinic, P2 1 /n, a=1061.94(3), b=1186.40(4), c=2007.88(7) pm, β= 104.575(1) , Z=4 for 1; monoclinic, C2/c, a=3128.81(12), b=878.42(3), c=2816.50(10) pm, β=92.1320(10) , Z=16 for 2; orthorhombic, P2 1 2 1 2 1 , a=1250.33(5), b=1391.46(6), c=2503.22(9) pm, Z=4 for 3. The structure of 1 contains an isolated octahedral [InBr 6 ] 3- ion and a Br - ion. The structure of 2 contains three different isolated octahedral [InBr 6 ] 3- ions. The structure of 3 has a corner-shared double-octahedral [In 2 Br 11 ] 5- ion and an isolated tetrahedral [InBr 4 ] - ion. The 81 Br nuclear quadrupole resonance (NQR) lines of the terminal Br atoms of the compounds are widely spread in frequency, and some of them show unusual positive temperature dependence. These observations manifest the N-H..Br-In hydrogen bond networks developed between the cations and anions to stabilize the crystal structures. The 81 Br NQR and differential thermal analysis (DTA) measurements have revealed the occurrence of unique phase transitions in 1 and 3. When the bond angles were estimated from the electric field gradient (EFG) directions calculated by the molecular orbital (MO) methods, accurate values were obtained for [InBr 6 ] 3- of 1 and for [In 2 Br 11 ] 5- and [InBr 4 ] - of 3, except for several exceptions in those for the latter two ions. On the other hand, the calculations of 81 Br NQR frequencies have produced up to 1.4 times higher values than the observed ones.

N- AND O-HETEROCYCLES PRODUCED FROM THE IRRADIATION OF BENZENE AND NAPHTHALENE IN H2O/NH3-CONTAINING ICES

International Nuclear Information System (INIS)

Materese, Christopher K.; Nuevo, Michel; Sandford, Scott A.

2015-01-01

Aromatic heterocyclic molecules are an important class of molecules of astrophysical and biological significance that include pyridine, pyrimidine, and their derivatives. Such compounds are believed to exist in interstellar and circumstellar environments, though they have never been observed in the gas phase. Regardless of their presence in the gas phase in space, numerous heterocycles have been reported in carbonaceous meteorites, which indicates that they are formed under astrophysical conditions. The experimental work described here shows that N- and O-heterocyclic molecules can form from the ultraviolet (UV) irradiation of the homocyclic aromatic molecules benzene (C 6 H 6 ) or naphthalene (C 10 H 8 ) mixed in ices containing H 2 O and NH 3 . This represents an alternative way to generate aromatic heterocycles to those considered before and may have important implications for astrochemistry and astrobiology

Heterolytic cleavage of ammonia N-H bond by bifunctional activation in silica-grafted single site Ta(V) imido amido surface complex. Importance of the outer sphere NH3 assistance

KAUST Repository

Gouré, Eric

2011-01-01

Ammonia N-H bond is cleaved at room temperature by the silica-supported tantalum imido amido complex [(≡SiO)2Ta(NH)(-NH2)], 2, if excess ammonia is present, but requires 150 °C to achieve the same reaction if only one equivalent NH3 is added to 2. MAS solid-state 15N NMR and in situ IR spectroscopic studies of the reaction of either 15N or 2H labeled ammonia with 2 show that initial coordination of the ammonia is followed by scrambling of either 15N or 2H among ammonia, amido and imido groups. Density functional theory (DFT) calculations with a cluster model [{(μ-O)[(H3SiO) 2SiO]2}Ta(NH)(-NH2)(NH3)], 2 q·NH3, show that the intramolecular H transfer from Ta-NH2 to TaNH is ruled out, but the H transfers from the coordinated ammonia to the amido and imido groups have accessible energy barriers. The energy barrier for the ammonia N-H activation by the Ta-amido group is energetically preferred relative to the Ta-imido group. The importance of excess NH3 for getting full isotope scrambling is rationalized by an outer sphere assistance of ammonia acting as proton transfer agent, which equalizes the energy barriers for H transfer from coordinated ammonia to the amido and imido groups. In contrast, additional coordinated ammonia does not favor significantly the H transfer. These results rationalize the experimental conditions used. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.

Singlet ground state in the spin-1/2 weakly coupled dimer compound NH4[ (V2O3)2(4,4'-b p y ) 2(H2PO4)(PO4)2] .0.5 H2O

Science.gov (United States)

Arjun, U.; Kumar, Vinod; Anjana, P. K.; Thirumurugan, A.; Sichelschmidt, J.; Mahajan, A. V.; Nath, R.

2017-05-01

We present the synthesis and a detailed investigation of structural and magnetic properties of polycrystalline NH4[(V2O3)2(4,4'-b p y ) 2(H2PO4) (PO4)2] .0.5 H2O by means of x-ray diffraction, magnetic susceptibility, electron spin resonance, and 31P nuclear magnetic resonance measurements. Temperature-dependent magnetic susceptibility could be described well using a weakly coupled spin-1/2 dimer model with an excitation gap Δ /kB≃26.1 K between the singlet ground state and triplet excited states and a weak interdimer exchange coupling J'/kB≃4.6 K. A gapped chain model also describes the data well with a gap of about 20 K. The electron spin resonance intensity as a function of temperature traces the bulk susceptibility nicely. The isotropic Landé g factor is estimated to be about g ≃1.97 , at room temperature. We are able to resolve the 31P NMR signal as coming from two inequivalent P sites in the crystal structure. The hyperfine coupling constant between 31P nucleus and V4 + spins is calculated to be Ahf(1 ) ≃2963 Oe/μB and Ahf(2 ) ≃1466 Oe/μB for the P(1) and P(2) sites, respectively. Our NMR shift and spin-lattice relaxation rate for both the 31P sites show an activated behavior at low temperatures, further confirming the singlet ground state. The estimated value of the spin gap from the NMR data measured in an applied field of H =9.394 T is consistent with the gap obtained from the magnetic susceptibility analysis using the dimer model. Because of a relatively small spin gap, NH4[(V2O3)2(4,4'-b p y ) 2(H2PO4) (PO4)2] .0.5 H2O is a promising compound for further experimental studies under high magnetic fields.

GAS PHASE STRUCTURE AND STABILITY OF COMPLEX FORMED BY H2O, NH3, H2S AND THEIR METHYL DERIVATIVES WITH THE CATION CO2+

Directory of Open Access Journals (Sweden)

Cahyorini Kusumawardani

2010-06-01

Full Text Available Ab initio molecular orbital calculations at the Hartree-Fock-Self Consistent Field (HF-SCF have been performed in order to determine the structure and gas phase energies of complex formed by the Lewis bases of H2O, NH3, H2S and their methyl derivatives with the cation Co2+. The relative basicities of the base studied depend on both the substituent. The gas-phase interaction energies computed by the SCF method including electron correlation Møller-Plesset 2 (MP2 dan Configuration Iteration (CI were comparable in accuracy. The binding energies computed by these two methods reach the targeted chemical accuracy.   Keywords: ab initio calculation, cobalt complex, structure stability

Asymmetric Baylis-Hillman Reaction between Chiral Activated Alkenes and Aromatic Aldehydes in Me3N/H2O/Solvent Medium

Institute of Scientific and Technical Information of China (English)

Ke HE; Zheng Hong ZHOU; Hong Ying TANG; Guo Feng ZHAO; Chu Chi TANG

2005-01-01

Chiral activated alkene, L-menthyl acrylate and (+)-N-α-phenylethyl acrylamide,induced asymmetric Baylis-Hillman reaction of aromatic aldehydes was realized at 25℃ for 7 days in Me3N/H2O/solvent homogeneous medium. The corresponding Baylis-Hillman adducts were obtained in good chemical yield with moderate to excellent diastereoselectivity (up to 99% de).

The effect of the gas composition on hydrogen-assisted NH3-SCR over Ag/Al2O3

DEFF Research Database (Denmark)

Tamm, Stefanie; Fogel, Sebastian; Gabrielsson, Pär

2013-01-01

In addition to high activity in hydrocarbon-SCR, Ag/Al2O3 catalysts show excellent activity for NOx reduction for H2-assisted NH3-SCR already at 200°C. Here, we study the influence of different gas compositions on the activity of a pre-sulfated 6wt% Ag/Al2O3 catalyst for NOx reduction, and oxidat...

MeB/sub 5/O/sub 8/(Me-Li, Na, K, NH/sub 4/)-H/sub 2/NCONHCOCH/sub 3/-H/sub 2/O system at 25 deg C

Energy Technology Data Exchange (ETDEWEB)

Skvortsov, V G; Fedorov, Yu A; Molodkin, A K; Tsekhanskij, R S

1986-06-01

Using the methods of isothermal solubility, densi- and refractometry, systems MB/sub 5/O/sub 8/ (M-Li, Na, K, NH/sub 4/)-acetylcarbamide - H/sub 2/O at 25 deg C have been studied. It is ascertained, that the systems investigated are of simple eutonic type.

Structure of (NH4)3H(SeO4)2 in high-temperature phases I and II

International Nuclear Information System (INIS)

Lukaszewicz, K.; Pietraszko, A.; Augustyniak, M.A.

1993-01-01

Triammonium hydrogenbis(tetraoxoselenate), (NH 4 ) 3 H(SeO 4 ) 2 , M r =341.04, Z=3, λ(Mo K anti α)=0.71073 A, F(000)=498. Phase I: trigonal, R anti 3m, a=6.090(1), c=22.759(5) A, V=731.0(2) A 3 , D x =2.32 g cm -3 , μ=68.7 cm -1 , T=355 K, R=0.0336 for 241 unique reflections with I>4σ(I). Phase II: trigonal, R anti 3, a=6.064(1), c=22.904(5) A, V=729.4(2) A 3 , D x =2.33 g cm -3 , μ=68.8 cm -1 , T=310 K, R=0.0374 for 397 unique reflections with I>4σ(I). In both phases, SeO 4 tetrahedra are linked by a dynamic system of symmetrically disordered hydrogen bonds in planes perpendicular to the trigonal axis. In phase II, SeO 4 tetrahedra deviate from the (210) plane owing to a small rotation of about 4 about the trigonal axis. In phase I, owing to symmetry enhancement, both orientations of SeO 4 tetrahedra are equally probable on both sides of (210), which is therefore a mirror plane. (orig.)

Synthesis, characterization, and application of Zn(NH 3)(CO3) for selective adsorptive separation of CO2

Science.gov (United States)

Khazeni, Naasser

This study explores the potential of Zn(NH3)(CO3) for selective CO2 separation. It develops a novel, highly controllable, single-pot synthesis approach based on urea hydrolysis and solvothermal aging to increase the feasibility of synthesizing Zn(NH3)(CO3), determines the structure of Zn(NH3)(CO3) in detail through single crystal X-ray diffraction and powder X-ray diffraction analyses, and performs adsorption analyses for the compound using CO2, N 2, H2, O2, and CH4 as adsorptives. Through adsorptive characterization, a systematic adsorbent selection screening is performed to assess the potential application of Zn(NH3)(CO 3) for adsorptive separation of CO2 from an upstream gas mixture of power generation, hydrogen production, and natural gas industries. Structural analysis shows Zn(NH3)(CO3) to have an inorganic helical framework that consists of a small helix of (ZnOCO) 2 and a large helix of (ZnOCO)4 with two ammines (NH 3) pendant from every other zinc. In terms of adsorption capacity and CO2 selectivity, Zn(NH3)(CO3) adsorbed 0.550 mmole/g CO2 at 293 K and 4500 mmHg, but only 0.047 mmole/g N 2, 0.084 mmole/g H2, 0.207 mmole/g 02, and 0.060 mmole/g CH4 at the same temperature and pressure. This behavior demonstrates considerable equilibrium selectivities - 36, 31, 63, and 11 - for separating CO2 from CH4, CO2 from H 2, CO2 from N2, and CO2 from 02, respectively. During adsorption, the pendant ammines act as the gates of check-valves: applied pressure opens the gates for adsorption; and during desorption, the gates are closed, trapping the adsorbates, until a reduction of pressure to near-atmospheric levels. Therefore, Zn(NH3)(CO3) exhibits low-pressure H3 or H4 hysteresis, indicating that the Zn(NH3)(CO3) framework can achieve gas storage at near-atmospheric pressures. Additionally, the compound proves structurally stable, with an adsorption decrease of 0.8% after 20 adsorption/desorption cycles - a factor that, considered with the other characteristics of Zn(NH

Preparation and characterization of Tb3+ and Tb(sal)3.nH2O doped PC:PMMA blend

International Nuclear Information System (INIS)

Dwivedi, Y.; Singh, A.K.; Prakash, Rajiv; Rai, S.B.

2011-01-01

Tb doped polycarbonate:poly(methyl methacrylate) (Tb-PC:PMMA) blend was prepared with varying proportions of PC and PMMA. Thermal and spectroscopic properties of the doped polymer have been investigated employing Fourier Transform Infrared (FTIR) absorption and differential scanning calorimetric (DSC) techniques. PC:PMMA blend (with 10 wt% PC and 90 wt% PMMA) shows better miscibility. Optical properties of the dopant Tb 3+ ions have been investigated using UV-vis absorption and fluorescence excited by 355 nm radiation. It is seen that luminescence intensity of Tb 3+ ion depends on PC:PMMA ratio and on Tb 3+ ion concentration. Concentration quenching is seen for TbCl 3 .6H 2 O concentration larger than 4 wt%. Addition of salicylic acid to the polymer blend increases the luminescence from Tb 3+ ions. Luminescence decay curve analysis affirms the non-radiative energy transfer from salicylic acid to Tb 3+ ions, which is identified as the reason behind this enhancement. - Highlights: → Blend formation is confirmed at PC/90PMMA, using FTIR and DSC techniques. → Absorption and bandgap studies of blend and parent components were studied. → Optical properties of Tb and Tb(sal) 3 .nH 2 O complex have been studied in PC/PMMA blend. → Luminescence decay curves confirm non-radiative energy transfer from Sal to Tb 3+ ions.

NH{sub 3} decomposition and simultaneous H{sub 2} separation with a commercial Pd-Cu-Ag/V membrane

Energy Technology Data Exchange (ETDEWEB)

Skodras, G.; Sakelleropoulos, G. [Centre for Research and Technology, Hellas, Ptolemaidas-Kozanis, Ptolemaida (Greece). Inst. for Solid Fuel Technolgy and Applications]|[Aristotle Univ. of Thessaloniki, Thessaloniki (Greece). Dept. of Chemical Engineering, Chemical Process Engineering Lab]|[Centre for Research and Technology, Hellas, Thermis, Thessaloniki (Greece). Chemical Process Research Inst.; Kaldis, S. [Centre for Research and Technology, Hellas, Thermis, Thessaloniki (Greece). Chemical Process Research Inst.; Topis, S. [Centre for Research and Technology, Hellas, Ptolemaidas-Kozanis, Ptolemaida (Greece). Inst. for Solid Fuel Technolgy and Applications]|[Aristotle Univ. of Thessaloniki, Thessaloniki (Greece). Dept. of Chemical Engineering, Chemical Process Engineering Lab; Koutsonikolas, D. [Aristotle Univ. of Thessaloniki, Thessaloniki (Greece). Dept. of Chemical Engineering, Chemical Process Engineering Lab; Grammelis, P. [Centre for Research and Technology, Hellas, Ptolemaidas-Kozanis, Ptolemaida (Greece). Inst. for Solid Fuel Technolgy and Applications

2006-07-01

The potential for integrated gasification combined cycle (IGCC) technology to emerge as an efficient and environmentally clean technology for power generation from coal gas was discussed. Ammonia (NH{sub 3}) is formed during gasification of coal. The concentration in coal gas depends on temperature, pressure, residence time and coal rank. In the gas turbine as much as 50 per cent of the NH{sub 3} in the fuel gas can be converted to NOx when the gas is combusted to produce power. A catalyst is required to bring NH{sub 3} levels down to acceptable levels for a gas turbine. This study examined the simultaneous ammonia (NH{sub 3}) decomposition and hydrogen (H{sub 2}) separation via a commercial Pd-Cu-Ag/V catalytic membrane reactor with 100 per cent H{sub 2} selectivity. A 16 per cent Ni/Al{sub 2}O{sub 3} catalyst was prepared and 88 per cent NH{sub 3} conversion was achieved with 20 per cent H{sub 2} in the feed stream. Increase of temperature and prolongation of residence time resulted in higher conversions. However, pressure increase lowered the decomposition due to the high H{sub 2} partial pressure. In order to develop kinetic equations, experiments at differential conversions were also performed. H{sub 2} diffusion was found to be the rate limiting step of H{sub 2} transport through the membrane. As such, H{sub 2} permeance increased exponentially with temperature. Mathematical model were then developed to describe the operation of the catalytic membrane reactor and to compare its performance with the conventional reactor. It was concluded that the conversion of NH{sub 3} can be increased significantly using the Pd-Cu-Ag/V membrane. 14 refs., 3 tabs., 7 figs.

Kinetics and branching ratios of the reactions NH2+NO2->N2O+H2O and NH2+NO2->H2NO+NO studied by pulse radiolysis combined with time-resolved infrared diode laser spectroscopy

DEFF Research Database (Denmark)

Meunier, H.; Pagsberg, Palle Bjørn; Sillesen, A.

1996-01-01

studied by monitoring the decay of NH2 and the simultaneous formation of N2O and NO by time-resolved infrared diode laser spectroscopy. The decay rate of NH2 was studied as a function of NO2 concentration to obtain an overall rate constant k(NH2 + NO2) = (1.35 +/- 0.15) X 10(-11) molecule(-1) cm(3) s(-1...

Experimental measurements of vapor-liquid equilibria of the H2O + CO2 + CH4 ternary system

Science.gov (United States)

Qin, J.; Rosenbauer, R.J.; Duan, Zhenhao

2008-01-01

Reported are the experimental measurements on vapor-liquid equilibria in the H2O + CO2 + CH4 ternary system at temperatures from (324 to 375) K and pressures from (10 to 50) MPa. The results indicate that the CH4 solubility in the ternary mixture is about 10 % to 40 % more than that calculated by interpolation from the Henry's law constants of the binary system, H2O + CH4, and the solubility of CO2 is 6 % to 20 % more than what is calculated by the interpolation from the Henry's law constants of the binary mixture, H 2O + CO2. ?? 2008 American Chemical Society.

Preparation and Study of NH3 Gas Sensing Behavior of Fe2O3 Doped ZnO Thick Film Resistors

Directory of Open Access Journals (Sweden)

D. R. Patil

2006-08-01

Full Text Available The preparation, characterization and gas sensing properties of pure and Fe2O3-ZnO mixed oxide semiconductors have been investigated. The mixed oxides were obtained by mixing ZnO and Fe2O3 in the proportion 1:1, 1:0.5 and 0.5:1. Pure ZnO was observed to be insensitive to NH3 gas. However, mixed oxides (with ZnO: Fe2O3 =1:0.5 were observed to be highly sensitive to ammonia gas. Upon exposure to NH3 gas, the barrier height of Fe2O3-ZnO intergranular regions decreases markedly due to the chemical transformation of Fe2O3 into well conducting ferric ammonium hydroxide leading to a drastic decrease in resistance. The crucial gas response was found to NH3 gas at 3500C and no cross response was observed to other hazardous and polluting gases. The effects of microstructure and doping concentration on the gas response, selectivity, response and recovery of the sensor in the presence of NH3 gas were studied and discussed.

Photocatalytic performance of TiO2 catalysts modified by H3PW12O40, ZrO2 and CeO2

Institute of Scientific and Technical Information of China (English)

CAI Tiejun; LIAO Yuchao; PENG Zhenshan; LONG Yunfei; WEI Zongyuan; DENG Qian

2009-01-01

The binary composite photo-catalysts CeO2/TiO2, ZrO2/TiO2 and the ternary composite photo-catalysts H3PW12O40-CeO2/TiO2,H2PW12O40-ZrO2/TiO2 were prepared by sol-gel method. The catalysts were characterized by thermogravimetric-differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The photocatalyfic elimination of methanol was used as model reaction to evaluate the photocatalytic activity of the composite catalysts under ultraviolet light irradiation. The effects of doped content, activation temperature, time, initial concentration of methanol and gas flow rate on the catalytic activity were investigated. The results showed that after doping a certain amount of CeO2 and ZrO2, crystaniTation process of TiO2 was restrained, particles of catalysts are smaller and more uniform. Doping ZrO2 not only significantly improved the catalytic activity, but also increased thermal stability. Doping H3PW12O40 also enhanced the catalytic activity. The catalytic activities of binary and ternary composite photocatalysts were significantly higher than tin-doped TiO2. The dynamics law of photocatalytic reaction over the binary CeO2/TiO2 and ZrO2/TiO2 catalysts has been studied. The activation energy 15.627 and 15.631 kJ/mol and pre-exponential factors 0.5176 and 0.9899 s-1 over each corresponding catalyst were obtained. This reaction accords to the first order dynamics law.

Startup and long-term performance of biotrickling filters packed with polyurethane foam and poplar wood chips treating a mixture of ethylmercaptan, H2S, and NH3.

Science.gov (United States)

Hernández, J; Lafuente, J; Prado, O J; Gabriel, D

2013-04-01

Treatment of a mixture of NH3, H2S, and ethylmercaptan (EM) was investigated for more than 15 months in two biotrickling filters packed with poplar wood chips and polyurethane foam. Inlet loads ranging from 5 to 10 g N-NH3 m-3 hr-1, from 5 to 16 g S-H2S m-3 hr-1, and from 0 to 5 g EM m-3 hr-1 were applied. During startup, the biotrickling filter packed with polyurethane foam was re-inoculated due to reduced biomass retention as well as a stronger effect of nitrogen compounds inhibition compared with the biotrickling filter packed with poplar wood. Accurate pH control between 7 and 7.5 favored pollutants abatement. In the long run, complete NH3 removal in the gas phase was achieved in both reactors, while H2S removal efficiencies exceeded 90%. EM abatement was significantly different in both reactors. A systematically lower elimination capacity was found in the polyurethane foam bioreactor. N fractions in the liquid phase proved that high nitrification rates were reached throughout steady-state operation in both bioreactors. CO2 production showed the extent of the organic packing material degradation, which allowed estimating its service lifetime in around 2 years. In the long run, the bioreactor packed with the organic packing material had a lower stability. However, an economic analysis indicated that poplar wood chips are a competitive alternative to inorganic packing materials in biotrickling filters. We provide new insights in the use of organic packing materials in biotrickling filters for the treatment of H2S, NH3, and mercaptans and compare them with polyurethane foam, a packing commonly used in biotrickling filters. We found interesting features related with the startup of the reactors and parameterized both the performance under steady-state conditions and the influence of the gas contact time. We provide relevant conclusions in the profitability of organic packing materials under a biotrickling filter configuration, which is infrequent but proven reliable

Mobile Column Measurements of HCHO, NO2, NH3, and C2H6 in Colorado during FRAPPE

Science.gov (United States)

Kille, N.; Volkamer, R. M.; Baidar, S.; Ortega, I.; Sinreich, R.; Hannigan, J. W.; Cooper, O. R.; Nussbaumer, E.; Pfister, G.

2015-12-01

Gases from anthropogenic sources have the potential to have a profound impact on air quality. Emissions from large cattle feedlots and ONG (Oil and Natural Gas) sites are comprised of NH3 (ammonia) and C2H6 (ethane) as pollutants. C2H6 contributes to photochemical ozone (O3) production and oxidation production of HCHO (formaldehyde). NH3 is a major source for reactive nitrogen to form particulate matter 2.5, which negatively affects human health. NO2 (nitrogen dioxide), emitted during combustion, is considered a large-scale pollutant and contributes to the formation of O3. Deploying an innovative suite of remote sensing instruments in a mobile laboratory, a Multi Axis Differential Optical Absorption Spectrometer (MAX-DOAS), a UV-Vis Spectrometer, and a Fourier Transform Infrared Spectrometer, we obtain mobile column measurements at high spatial and temporal resolution, 2 seconds for the UV-Vis and IR spectrometers and 20 seconds for the MAX-DOAS. Within the scope of the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) we measure total columns of HCHO, NO2, NH3, and C2H6 using the University of Colorado mobile laboratory. Emissions of urban areas, agriculture, and ONG sites were studied. For the measurement of total columns the solar occultation flux method has been applied. We measured significant variability in the columns. The measurement of total columns allows one to determine the emission flux and source strength when driving a closed box around or upwind and downwind of a source with the mobile laboratory. We present results from select research drives.

Systems Li2B4O7 (Na2B4O7, K2B4O7)-N2H3H4OH-H2O at 25 deg C

International Nuclear Information System (INIS)

Skvortsov, V.G.; Sadetdinov, Sh.V.; Akimov, V.M.; Mitrasov, Yu.N.; Petrova, O.V.; Klopov, Yu.N.

1994-01-01

Phase equilibriums in the Li 2 B 4 O 7 (Na 2 B 4 O 7 , K 2 B 4 O 7 )-N 2 H 3 H 4 OH-H 2 O systems were investigated by methods of isothermal solubility, refractometry and PH-metry at 25 deg C for the first time. Lithium and sodium tetraborates was established to form phases of changed composition mM 2 B 4 O 7 ·nN 2 H 3 C 2 H 4 OH·XH 2 O, where M=Li, Na with hydrazine ethanol. K 2 B 4 O 7 ·4H 2 O precipitates in solid phase in the case of potassium salt. Formation of isomorphous mixtures was supported by X-ray diffraction and IR spectroscopy methods

Dynamics of glycerine and water transport across human skin from binary mixtures.

Science.gov (United States)

Ventura, S A; Kasting, G B

2017-04-01

Skin transport properties of glycerine and water from binary mixtures contacting human skin were determined to better understand the mechanism of skin moisturization by aqueous glycerine formulations. Steady-state permeation for 3 H 2 O and 14 C-glycerine across split-thickness human skin in vitro and desorption dynamics of the same permeants in isolated human stratum corneum (HSC) were experimentally determined under near equilibrium conditions. These data were compared to a priori values developed in the context of a thermodynamic model for binary mixtures of glycerine and water and a previously determined water sorption isotherm for HSC. This allowed the estimation of diffusion and partition coefficients for each permeant in the HSC, as well as HSC thickness, as a function of composition of the contacting solution. These data may be used to estimate water retention and associated HSC swelling related to the absorption and slow release of glycerine from the skin. It took 6+ days for glycerine to completely desorb from HSC immersed in glycerine/water binary solutions. Desorption of both 3 H 2 O and 14 C-glycerine from HSC was slower in pure water than from binary mixtures, a result that is largely explained by the greater swelling of HSC in water. Parametric relationships were developed for water and glycerine intradiffusivities in HSC as functions of HSC water content, and a mutual diffusion coefficient was estimated by analogy with glycerine/water binary solutions. The intradiffusivity of 14 C-glycerine in HSC as inferred from sorption/desorption experiments was shown to be approximately 10-fold less than that inferred from permeation experiments, whereas the corresponding values for 3 H 2 O were comparable. These studies confirm that glycerine enters HSC in substantial quantities and has a long residence time therein. The coupling between bulk water and glycerine transport projected from binary solution data suggests the net effect of glycerine is to slow water

Aluminum (III) and gallium (III) complexes with methyliminodiacetic acid: Crystal structures of Cat[M(Mida)2] (Cat+=Na, K, NH4; M3+=Al, Ga) and Me4N[Ga(Mida)2]·H2O

International Nuclear Information System (INIS)

Ilyukhin, A.B.; Petrosyants, S.P.; Milovanov, S.V.; Malyarik, M.A.

1997-01-01

The bis chelate complexes Cat[M(Mida) 2 ] and Me 4 N[Ga(Mida) 2 ]·H 2 O are synthesized from aqueous solutions M(NO 3 ) 3 -2H 2 Mida-CatOH (M 3+ =Al, Ga; Cat + =Na, K, NH 4 ) and Ga(OH) 3 -2H 2 Mida-Me 4 NOH. The crystal structures of the isostructural compounds Cat[M(Mida) 2 ] (Cat=Na, M=Al; Cat=K, M=Al; Cat=Na, M=Ga) and Me 4 N[Ga(Mida) 2 ]·H 2 O are determined by X-ray structure analysis. According to the X-ray powder diffraction analysis, all the six compounds Cat[M(Mida) 2 ] (Cat=Na, K, NH 4 ; M=Al, Ga) are isostructural. The octahedral anion in Cat[M(Mida) 2 ] and Me 4 N[Ga(Mida) 2 ]·H 2 O exhibits a trans(N)- fac configuration

Adsorção de íons sulfato em ZrO2.nH2O preparado pelo método da precipitação convencional e da precipitação em solução homogênea Adsorption of sulfate ions in ZrO2.nH2O prepared by conventional precipitation and homogeneous solution methods

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L. A. Rodrigues

2009-03-01

Full Text Available Este trabalho visa a preparação, caracterização e estudo da adsorção de íons sulfato em óxido de zircônio hidratado preparado pelos métodos da precipitação convencional e da precipitação em solução homogênea. Os materiais obtidos foram caracterizados por difração de raios X, análise termogravimétrica, microscopia eletrônica de varredura e análise de área superficial específica pelo método BET. Através da constante Q0, relacionada com a capacidade de adsorção máxima, observou-se que o ZrO2.nH2O/PSH possui maior capacidade de adsorção para íons sulfato que o ZrO2.nH2O/PC. Pelos resultados de ΔG, observou-se que os íons sulfato foram adsorvidos através de reações energeticamente favoráveis para toda a faixa de concentração estudada.This work reports the preparation, characterization and adsorption study of sulfate on hydrous zirconium oxides prepared by conventional and homogeneous solution precipitation methods. The materials prepared were characterized by X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and surface area measurements. Through the Q0 constant, related with the capacity of maximum adsorption, it was observed that the ZrO2.nH2O/PSH presented better adsorption capacity than ZrO2.nH2O/PC. By results of ΔG, it was observed that sulfate ions had been adsorbed through favorable reactions for all studied concentration ranges.

Laboratory study on new particle formation from the reaction OH + SO2: influence of experimental conditions, H2O vapour, NH3 and the amine tert-butylamine on the overall process

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J. Curtius

2010-08-01

Full Text Available Nucleation experiments starting from the reaction of OH radicals with SO2 have been performed in the IfT-LFT flow tube under atmospheric conditions at 293±0.5 K for a relative humidity of 13–61%. The presence of different additives (H2, CO, 1,3,5-trimethylbenzene for adjusting the OH radical concentration and resulting OH levels in the range (4–300 ×105 molecule cm−3 did not influence the nucleation process itself. The number of detected particles as well as the threshold H2SO4 concentration needed for nucleation was found to be strongly dependent on the counting efficiency of the used counting devices. High-sensitivity particle counters allowed the measurement of freshly nucleated particles with diameters down to about 1.5 nm. A parameterization of the experimental data was developed using power law equations for H2SO4 and H2O vapour. The exponent for H2SO4 from different measurement series was in the range of 1.7–2.1 being in good agreement with those arising from analysis of nucleation events in the atmosphere. For increasing relative humidity, an increase of the particle number was observed. The exponent for H2O vapour was found to be 3.1 representing an upper limit. Addition of 1.2×1011 molecule cm−3 or 1.2×1012 molecule cm−3 of NH3 (range of atmospheric NH3 peak concentrations revealed that NH3 has a measureable, promoting effect on the nucleation rate under these conditions. The promoting effect was found to be more pronounced for relatively dry conditions, i.e. a rise of the particle number by 1–2 orders of magnitude at RH = 13% and only by a factor of 2–5 at RH = 47% (NH3 addition: 1.2×1012 molecule cm−3. Using the amine tert-butylamine instead of NH3, the enhancing impact of the base for nucleation and particle growth appears to be stronger. Tert-butylamine addition of about 1010 molecule cm−3 at RH = 13% enhances particle formation by about two orders of magnitude, while for NH3 only a small or negligible

Substituent Effects on the Hydrogen Bonding between 4-Substituted Phenols and HF, H2O, NH3

Institute of Scientific and Technical Information of China (English)

程宇辉; 傅尧; 刘磊; 郭庆祥

2003-01-01

Density function theory UB3LYP/6-31+g(d) calculations were performed to study the hydrogen bonds between para-substituted phenols and HF, H2O, or NH3. It revealed that many properties of the non-covalent complexes, such as the interaction energies, donor-acceptor distances, bond lengths and vibration frequencies, showed well-defined substituent effects. Therefore, from the substituent effects not only the mechanism of a certain non-covalent interaction can be better understood, but also the interaction energies and structures of a certain non-covalent complex, which otherwise might be very hard or resource-consuming to estimate, can be easily predicted.

Measurements and modeling of absorption by CO2 + H2O mixtures in the spectral region beyond the CO2 ν3-band head

Science.gov (United States)

Tran, H.; Turbet, M.; Chelin, P.; Landsheere, X.

2018-05-01

In this work, we measured the absorption by CO2 + H2O mixtures from 2400 to 2600 cm-1 which corresponds to the spectral region beyond the ν3 band head of CO2. Transmission spectra of CO2 mixed with water vapor were recorded with a high-resolution Fourier-transform spectrometer for various pressure, temperature and concentration conditions. The continuum absorption by CO2 due to the presence of water vapor was determined by subtracting from measured spectra the contribution of local lines of both species, that of the continuum of pure CO2 as well as of the self- and CO2-continua of water vapor induced by the H2O-H2O and H2O-CO2 interactions. The obtained results are in very good agreement with the unique previous measurement (in a narrower spectral range). They confirm that the H2O-continuum of CO2 is significantly larger than that observed for pure CO2. This continuum thus must be taken into account in radiative transfer calculations for media involving CO2+ H2O mixture. An empirical model, using sub-Lorentzian line shapes based on some temperature-dependent correction factors χ is proposed which enables an accurate description of the experimental results.

Quasielastic neutron scattering and infra-red band contour study of H2O reorientations in [Ni(H2O)6] (ClO4)2

International Nuclear Information System (INIS)

Janik, J.A.; Janik, J.M.; Otnes, K.; Stanek, T.

1980-01-01

IR band contour measurements carried out for [Ni(H 2 O) 6 ] (ClO 4 ) 2 revealed an existence of fast H 2 O 180 deg flips around Ni-O axes at room temperatures. These flips were subjected to a more accurate study by the quasielastic neutron scattering method. Correlation times of the order of picosecond were obtained for room temperatures and the barrier to rotation of ca. 7 kcal/mole. The results are compared to those previously obtained for [Mg(H 2 O) 6 ] (ClO 4 ) 2 and also to those for [Ni(NH 3 ) 6 ] (ClO 4 ) 2 and [Mg(NH 3 ) 6 ] (ClO 4 ) 2 . (author)

Photochemical oxidation of short-chain polychlorinated n-alkane mixtures using H2O2/UV and the photo-Fenton reaction

OpenAIRE

Ken J. Friesen; Taha M. El-Morsi; Alaa S. Abd-El-Aziz

2004-01-01

The photochemical oxidation of a series of short-chain polychlorinated n-alkane (PCA) mixtures was investigated using H2O2/UV and modified photo-Fenton conditions (Fe3+/H2O2/UV) in both Milli-Q and lake water. All PCA mixtures, including chlorinated (Cl5 to Cl8) decanes, undecanes, dodecanes and tridecanes degraded in 0.02 M H2O2/UV at pH 2.8 in pure water, with 80±4% disappearance after 3 h of irradiation using a 300 nm light source. Degradation was somewhat enhanced under similar conditions...

Photocatalytic degradation of Basic Red 46 and Basic Yellow 28 in single and binary mixture by UV/TiO2/periodate system

International Nuclear Information System (INIS)

Goezmen, Belgin; Turabik, Meral; Hesenov, Arif

2009-01-01

The present study deals with the investigation of photocatalytic degradation and mineralization of C.I. Basic Red 46 (BR46) and C.I. Basic Yellow 28 (BY28) dyes in single and binary solutions as a function of periodate ion concentration (IO 4 - ), irradiation time, initial pH and initial dye concentrations. First order derivative spectrophotometric method was used for to simultaneous analysis of BY28 and BR46 in binary mixtures. Langmuir-Hinshelwood kinetic model was applied to experimental data and apparent reaction rate constant values were calculated. The apparent degradation rate constant values of BR46 were higher than those of BY28 for all experiments in single dye solutions. On the other hand, the significant reductions were observed for the apparent degradation rate constant values of the BR46 in the presence of BY28 in binary solutions whereas TOC removal efficiency slightly enhanced in binary system. The highest TOC removal efficiency was obtained at pH 3.0 by adding 5 mM periodate ion in to the solution in the presence of 1 g/L TiO 2 for both dye solutions. After 3 h illumination, 68, 76 and 75% mineralization were found for 100 mg/L BY28, 100 mg/L BR46 and 50 + 50 mg/L mixed solutions, respectively.

Oxidation Properties of Nitrogen-Doped Silicon Films Deposited from Si2H6 and NH3

Science.gov (United States)

Scheid, Emmanuel; Boyer, Pierre; Samitier, Josep; Hassani, Ahmed

1994-03-01

Si2H6/NH3 gas mixture was employed to obtain, by low-pressure chemical vapor deposition (LPCVD) at low temperature, nitrogen-doped silicon (NIDOS) films with various N/Si ratios. Thermal oxide was grown in dry oxygen at 900°C and 1100°C on NIDOS films. The result indicates that the nitrogen content of NIDOS films, assessed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR), greatly influences their oxidation rate.

Synthesis and study of NH4[HSiUO6]·0.5H2O

International Nuclear Information System (INIS)

Chernorukov, N.G.; Kortikov, V.E.

2000-01-01

Previously unknown ammonium uranosilicate of NH 4 [HSiUO 6 ]·0.5H 2 O composition is synthesised by precipitation from aqueous solution containing ammonium chloride, uranyl nitrate and quartz glass with the size of granules ≤ 2. On evidence of X-ray diffraction ammonium uranosilicate is a full crystallographic analog of proper lithium and potassium derivatives with approaching parameters of crystal lattices: a= 7.01(2), b=7.03(8), c=6.65(9) A, β=105.6(0) Deg. Functional composition and peculiarity of ammonium uranosilicate structure are detected by IR spectroscopic study. Scheme of thermal decomposition of ammonium uranosilicate is demonstrated based on thermal gravimetric and X-ray diffraction measurements. NH 4 [HSiUO 6 ]·0.5H 2 O is among of morphotropic raw of A 1/k k HSiUO 6 ·nH 2 O [ru

Effects of the addition of H2O and NH4OH in the electrical properties of thin films of Y2O3 deposited by pyrolytic spray

International Nuclear Information System (INIS)

Herrera S, H.J.; Alarcon F, G.; Aguilar F, M.; Falcony, C.; Garcia H, M.; Guzman M, J.; Araiza I, J.J.

2005-01-01

In this work we studied the electrical properties of yttrium oxide thin films obtained by spray pyrolysis from Y(acac) 3 and N,N-DMF. The films were deposited on Si(100) substrates at temperatures of 400, 450, 500 and 550 C. The electrical characteristic of the films was improved when a mist of H 2 O and/or NH 4 0H was simultaneously added to the deposition system. Current and capacitance versus voltage measurements were obtained when the Y 2 O 3 films were integrated in MOS (Metal-Oxide-Semiconductor) structures. Y 2 O 3 films with a dielectric constant up to 15 were obtained. The films can stand electric fields up to 2 MV/cm. An interface state density in the range of 10 10 -10 11 cm -2 eV -1 was measured at midgap from the high and low frequency capacitance measurements. (Author)

Negative ion photoelectron spectroscopy of solvated electron cluster anions, (H2O)n- and (NH3)n-

International Nuclear Information System (INIS)

Lee, G.H.; Arnold, S.T.; Eaton, J.G; Sarkas, H.W.; Bowen, K.H.; Ludewigt, C.; Haberland, H.

1991-01-01

The photodetachment spectra of (H 2 O) - n=2-69 and (NH 3 ) - n=41-1100 have been recorded, and vertical detachment energies (VDEs) were obtained from the spectra. For both systems, the cluster anion VDEs increase smoothly with increasing sizes and most species plot linearly with n -1/3 , extrapolating to a VDE (n = ∞) value which is very close to the photoelectric threshold energy for the corresponding condensed phase solvated electron system. The linear extrapolation of this data to the analogous condensed phase property suggests that these cluster anions are gas phase counterparts to solvated electrons, i.e. they are embryonic forms of hydrated and ammoniated electrons which mature with increasing cluster size toward condensed phase solvated electrons. (orig.)

Negative ion photoelectron spectroscopy of solvated electron cluster anions, (H2O){/n -} and (NH3){/n -}

Science.gov (United States)

Lee, G. H.; Arnold, S. T.; Eaton, J. G.; Sarkas, H. W.; Bowen, K. H.; Ludewigt, C.; Haberland, H.

1991-03-01

The photodetachment spectra of (H2O){/n =2-69/-} and (NH3){/n =41-1100/-} have been recorded, and vertical detachment energies (VDEs) were obtained from the spectra. For both systems, the cluster anion VDEs increase smoothly with increasing sizes and most species plot linearly with n -1/3, extrapolating to a VDE ( n=∞) value which is very close to the photoelectric threshold energy for the corresponding condensed phase solvated electron system. The linear extrapolation of this data to the analogous condensed phase property suggests that these cluster anions are gas phase counterparts to solvated electrons, i.e. they are embryonic forms of hydrated and ammoniated electrons which mature with increasing cluster size toward condensed phase solvated electrons.

Solid-state thermal decomposition of the [Co(NH3)5CO3]NO3·0.5H2O complex: A simple, rapid and low-temperature synthetic route to Co3O4 nanoparticles

International Nuclear Information System (INIS)

Farhadi, Saeid; Safabakhsh, Jalil

2012-01-01

Highlights: ► [Co(NH 3 ) 5 CO 3 ]NO 3 ·0.5H 2 O complex was used for preparing pure Co 3 O 4 nanoparticles. ► Co 3 O 4 nanoparticles were prepared at low temperature of 175 °C. ► Co 3 O 4 nanoparticles show a weak ferromagnetic behaviour at room temperature. ► The method is simple, low-cost and suitable for the production of Co 3 O 4 . - Abstract: Co 3 O 4 nanoparticles were easily prepared via the decomposition of the pentammine(carbonato)cobalt(III) nitrate precursor complex [Co(NH 3 ) 5 CO 3 ]NO 3 ·0.5H 2 O at low temperature (175 °C). The product was characterized by thermal analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV–visible spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, Brunauer–Emmett–Teller (BET) specific surface area measurements and magnetic measurements. The FT-IR, XRD, Raman and EDX results indicated that the synthesized Co 3 O 4 nanoparticles are highly pure and have a single phase. The TEM analysis revealed nearly uniform and quasi-spherical Co 3 O 4 nanoparticles with an average particle size of approximately 10 nm. The optical absorption spectrum of the Co 3 O 4 nanoparticles showed two direct band gaps of 2.18 and 3.52 eV with a red shift in comparison with previous reported values. The prepared Co 3 O 4 nanoparticles showed a weak ferromagnetic behaviour that could be attributed to uncompensated surface spins and/or finite-size effects. Using the present method, Co 3 O 4 nanoparticles can be produced without expensive organic solvents and complicated equipment. This simple, rapid, safe and low-cost synthetic route can be extended to the synthesis of other transition-metal oxides.

Descent Without Modification? The Thermal Chemistry of H2O2 on Europa and Other Icy Worlds

Science.gov (United States)

Loeffler, Mark Josiah; Hudson, Reggie Lester

2015-01-01

The strong oxidant H2O2 is known to exist in solid form on Europa and is suspected to exist on several other Solar System worlds at temperatures below 200 K. However, little is known of the thermal chemistry that H2O2 might induce under these conditions. Here, we report new laboratory results on the reactivity of solid H2O2 with eight different compounds in H2O-rich ices. Using infrared spectroscopy, we monitored compositional changes in ice mixtures during warming. The compounds CH4 (methane), C3H4 (propyne), CH3OH (methanol), and CH3CN (acetonitrile) were unaltered by the presence of H2O2 in ices, showing that exposure to either solid H2O2 or frozen H2O+H2O2 at cryogenic temperatures will not oxidize these organics, much less convert them to CO2. This contrasts strongly with the much greater reactivity of organics with H2O2 at higher temperatures, and particularly in the liquid and gas phases. Of the four inorganic compounds studied, CO, H2S, NH3, and SO2, only the last two reacted in ices containing H2O2, NH3 making NHþ 4 and SO2 making SO2 4 by H+ and e - transfer, respectively. An important astrobiological conclusion is that formation of surface H2O2 on Europa and that molecule's downward movement with H2O-ice do not necessarily mean that all organics encountered in icy subsurface regions will be destroyed by H2O2 oxidation.

Densities, viscosities, and refractive indexes for {C2H5CO2(CH2)2CH3+C6H13OH+C6H6} at T=308.15 K

International Nuclear Information System (INIS)

Casas, Herminio; Garcia-Garabal, Sandra; Segade, Luisa; Cabeza, Oscar.; Franjo, Carlos; Jimenez, Eulogio

2003-01-01

In this work we present densities, kinematic viscosities, and refractive indexes of the ternary system {C 2 H 5 CO 2 (CH 2 ) 2 CH 3 +C 6 H 13 OH+C 6 H 6 } and the corresponding binary mixtures {C 2 H 5 CO 2 (CH 2 ) 2 CH 3 +C 6 H 6 }, {C 2 H 5 CO 2 (CH 2 ) 2 CH 3 +C 6 H 13 OH}, and {C 6 H 13 OH+C 6 H 6 }. All data have been measured at T=308.15 K and atmospheric pressure over the whole composition range. The excess molar volumes, dynamic viscosity deviations, and changes of the refractive index on mixing were calculated from experimental measurements. The results for binary mixtures were fitted to a polynomial relationship to estimate the coefficients and standard deviations. The Cibulka equation has been used to correlate the experimental values of ternary mixtures. Also, the experimental values obtained for the ternary mixture were used to test the empirical methods of Kohler, Jacob and Fitzner, Colinet, Tsao and Smith, Toop, Scatchard et al., and Hillert. These methods predict excess properties of the ternary mixtures from those of the involved binary mixtures. The results obtained for dynamic viscosities of the binary mixtures were used to test the semi-empirical relations of Grunberg-Nissan, McAllister, Auslaender, and Teja-Rice. Finally, the experimental refractive indexes were compared with the predicted results for the Lorentz-Lorenz, Gladstone-Dale, Wiener, Heller, and Arago-Biot equations. In all cases, we give the standard deviation between the experimental data and that calculated with the above named relations

Investigation of the Dynamics Of NH{sup +}{sub 4} and H{sub 2}O Molecular Groups in Crystals; Etude de la Dynamique des Groupes Moleculaires NH{sup +}{sub 4} et H{sub 2}O dans les Cristaux; 0418 0421 0421 041b 0415 0414 041e 0412 0410 041d 0418 0415 0414 0418 041d 0410 041c 0418 041a 0418 041c 041e 041b 0415 041a 0423 041b 042f 0420 041d 042b 0425 0413 0420 0423 041f 041f NH{sup +}{sub 4} H H{sub 2}O 0412 041a 0420 0418 0421 0422 0410 041b 041b 0410 0425 ; Estudio de la Dinamica de los Grupos Moleculares NH{sup +}{sub 4} Y H{sub 2}O en Cristales

Energy Technology Data Exchange (ETDEWEB)

Bajorek, A.; Machehina, T. A.; Parlin' Ski, K. [Ob' edinennyj Institut Jadernyh Issledovanij, Dubna, SSSR (Russian Federation)

1965-06-15

The authors give the results of thermal neutron scattering measurements in crystals containing ammonium ion (NH{sub 4}CI, NH{sub 4}Br, NH{sub 4}I, NH{sub 4}F, NH{sub 4}NO{sub 3}, NH{sub 4}CNS, (NH{sub 4}){sub 2}SO{sub 4}, (NH{sub 4}){sub 2}S{sub 2}O{sub 8}, (NH{sub 4}){sub 2}Cr{sub 2}O{sub 7}, (NH{sub 4}){sub 2}CO{sub 3}) and water of crystallization (BaCl{sub 2} * 2H{sub 2}O, SrCl{sub 2} * 6H{sub 2}O, CuSO{sub 4} * 5H{sub 2}O) . The investigations were made to study the influence of various crystal lattices on the dynamics of these groups and the connection between scattering processes and phase transitions. In spite of the structural differences of the substances examined, the spectra obtained at the temperature of liquid nitrogen proved to be similar. As a rule, there are two peaks, one in the 15-20 meV energy transfer range, and the other in the 35-70 meV range, associated with the torsional vibrations of.ammonium ions. The intensity of the peaks depends on the structure of the substances under examination and falls as the sample temperature rises. It was found that there is a jump in the elastic region of the spectrum at certain phase transitions (in the cases of NH{sub 4}I, NH{sub 4}NO{sub 3} and (NH{sub 4}){sub 2}SO{sub 4}). At increased temperatures an additional peak appears in NH{sub 4}Cl, NH{sub 4}Br and (NH{sub 4}){sub 2}(COO){sub 2} to the lower energy side of the rotational retardation peak. The spectra of neutrons scattered in crystals containing water of crystallization also resemble one another. Three groups of peaks are observed in the spectra, associated with optical vibrations and rotational retardation of the water molecules. (author) [French] Us auteurs indiquent les resultats qu'ils ont obtenus en mesurant la diffusion des neutrons thermiques par des cristaux contenant un ion ammonium (NH{sub 4}CI, NH{sub 4}Br, NH{sub 4}I, NH{sub 4}F, NH{sub 4}NO{sub 3}, NH{sub 4}CNS, (NH{sub 4}){sub 2}SO{sub 4}, (NH{sub 4}){sub 2}S{sub 2}O{sub 8}, (NH{sub 4

Process for uranium separation and preparation of UO4.2NH3.2HF

International Nuclear Information System (INIS)

Dokuzoguz, H.Z.

1976-01-01

A process for treating the aqueous effluents that are produced in converting gaseous UF 6 (uranium hexafluoride) into solid UO 2 (uranium dioxide) by way of an intermediate (NH 4 ) 4 UO 2 (CO 3 ) 3 (''AUC'' Compound) is disclosed. These effluents, which contain large amounts of NH 4 + , CO 3 2- , F - , and a small amount of U are mixed with H 2 SO 4 (sulfuric acid) in order to expel CO 2 (carbon dioxide) and thereby reduce the carbonate concentration. The uranium is precipitated through treatment with H 2 O 2 (hydrogen peroxide) and the fluoride is easily recovered in the form of CaF 2 (calcium fluoride) by contacting the process liquid with CaO (calcium oxide). The presence of SO 4 2- (sulfate) in the process liquid during CaO contacting seems to prevent the development of a difficult-to-filter colloid. The process also provides for NH 3 recovery and recycling. Liquids discharged from the process, moreover, are essentially free of environmental pollutants. The waste treatment products, i.e., CO 2 , NH 3 , and U are economically recovered and recycled back into the UF 6 → UO 2 conversion process. The process, moreover, recovers the uranium as a precipitate in the second stage. This precipitate is a new inorganic chemical compound UO 4 .2NH 3 .2HF [uranyl peroxide-2-ammonia-2-(hydrogen fluoride)

Substituent Effects on the Hydrogen Bonding Between Phenolate and HF, H2O and NH3

Institute of Scientific and Technical Information of China (English)

无

2002-01-01

B3LYP/6-31+g(d) calculations were performed on the hydrogen bonded complexes between substituted phenolates and HF, H2O as well as NH3. It was found that some properties of the non-covalent complexes, including the interaction energies, donor-acceptor (host-guest) distances, bond lengths, and vibration frequencies, could show well-defined substituent effects. Thus, from the substituent studies we can not only understand the mechanism of a particular non-covalent interaction better, but also easily predict the interaction energies and structures of a particular non-covalent complex, which might otherwise be very hard or resource-consuming to be known. This means that substituent effect is indeed a useful tool to be used in supramolecular chemistry and therefore, many valuable studies remain to be carried out.

Glass transition behaviour of the quaternary ammonium type ionic liquid, {[DEME][I] + H2O} mixtures

International Nuclear Information System (INIS)

Imai, Yusuke; Abe, Hiroshi; Matsumoto, Hitoshi; Shimada, Osamu; Hanasaki, Tomonori; Yoshimura, Yukihiro

2011-01-01

By a simple DTA system, the glass transition temperatures of the quaternary ammonium type ionic liquid, {N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium iodide, [DEME][I] + H 2 O} mixtures after quick pre-cooling were measured as a function of water concentration (x mol% H 2 O). Results were compared with the previous results of {[DEME][BF 4 ] + H 2 O} mixtures in which double glass transitions were observed in the water concentration region of (16.5 to 30.0) mol% H 2 O. Remarkably, we observed the double glass transition phenomenon in {[DEME][I] + H 2 O} mixtures too, but the two-T g s regions lie towards the water-rich side of (77.5 to 85.0) mol% H 2 O. These clearly reflect the difference in the anionic effect between BF 4 - and I - on the water structure. The end of the glass-formation region of {[DEME][I] + H 2 O} mixtures is around x = 95.0 mol% H 2 O, and this is comparable to that of {[DEME][BF 4 ] + H 2 O} mixtures (x = 96.0 mol% H 2 O).

Wet Mechanochemical Processing of Celestine using (NH42CO3

Directory of Open Access Journals (Sweden)

Deniz Bingöl

2017-06-01

Full Text Available In this study, traditional (univariate method of processing to the wet mechanochemical treatment were applied to obtain both SrCO3 and (NH42SO4 from celestite (SrSO4-(NH42CO3-H2O mixtures in a planetary ball mill. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and chemical analysis were used to analyze products formed during wet milling. A hydrometallurgical process was carried out to examine milling time, ball to grinding material mass ratio, (NH42CO3 to SrSO4 mole ratio and rotational speed of the mill in a planetary mill. Under optimum conditions, a conversion approaching 100% of SrCO3 was obtained.

N- AND O-HETEROCYCLES PRODUCED FROM THE IRRADIATION OF BENZENE AND NAPHTHALENE IN H{sub 2}O/NH{sub 3}-CONTAINING ICES

Energy Technology Data Exchange (ETDEWEB)

Materese, Christopher K.; Nuevo, Michel; Sandford, Scott A., E-mail: christopher.k.materese@nasa.gov [NASA Ames Research Center, Moffett Field, CA 94035 (United States)

2015-02-20

Aromatic heterocyclic molecules are an important class of molecules of astrophysical and biological significance that include pyridine, pyrimidine, and their derivatives. Such compounds are believed to exist in interstellar and circumstellar environments, though they have never been observed in the gas phase. Regardless of their presence in the gas phase in space, numerous heterocycles have been reported in carbonaceous meteorites, which indicates that they are formed under astrophysical conditions. The experimental work described here shows that N- and O-heterocyclic molecules can form from the ultraviolet (UV) irradiation of the homocyclic aromatic molecules benzene (C{sub 6}H{sub 6}) or naphthalene (C{sub 10}H{sub 8}) mixed in ices containing H{sub 2}O and NH{sub 3}. This represents an alternative way to generate aromatic heterocycles to those considered before and may have important implications for astrochemistry and astrobiology.

The Role of Fe2O3 Species in Depressing the Formation of N2O in the Selective Reduction of NO by NH3 over V2O5/TiO2-Based Catalysts

Directory of Open Access Journals (Sweden)

Moon Hyeon Kim

2018-03-01

Full Text Available Promotion of 2.73% Fe2O3 in an in-house-made V2O5-WO3/TiO2 (VWT and a commercial V2O5-WO3/TiO2 (c-VWT has been investigated as a cost effective approach to the suppression of N2O formation in the selective catalytic reduction of NO by NH3 (NH3-SCR. The promoted VWT and c-VWT catalysts all gave a significantly decreased N2O production at temperatures >400 °C compared to the unpromoted samples. However, such a promotion led to the loss in high temperature NO conversion, mainly due to the oxidation of NH3 to N-containing gases, particularly NO. Characterization of the unpromoted and promoted catalysts using X-ray diffraction (XRD, NH3 adsorption-desorption, and Raman spectroscopy techniques could explain the reason why the promotion showed much lower N2O formation levels at high temperatures. The addition of Fe2O3 to c-VWT resulted in redispersion of the V2O5 species, although this was not visible for 2.73% Fe2O3/VWT. The iron oxides exist as a highly-dispersed noncrystalline α-Fe2O3 in the promoted catalysts. These Raman spectra had a new Raman signal that could be tentatively assigned to Fe2O3-induced tetrahedrally coordinated polymeric vanadates and/or surface V-O-Fe species with significant electronic interactions between the both metal oxides. Calculations of the monolayer coverage of each metal oxide and the surface total coverage are reasonably consistent with Raman measurements. The proposed vanadia-based surface polymeric entities may play a key role for the substantial reduction of N2O formed at high temperatures by NH3 species adsorbed strongly on the promoted catalysts. This reaction is a main pathway to greatly suppress the extent of N2O formation in NH3-SCR reaction over the promoted catalysts.

Nanoparticles of [Fe(NH2-trz)3]Br2.3H2O (NH2-trz=2-amino-1,2,4-triazole) prepared by the reverse micelle technique: influence of particle and coherent domain sizes on spin-crossover properties.

Science.gov (United States)

Forestier, Thibaut; Kaiba, Abdellah; Pechev, Stanislav; Denux, Dominique; Guionneau, Philippe; Etrillard, Céline; Daro, Nathalie; Freysz, Eric; Létard, Jean-François

2009-06-15

This paper describes the synthesis of iron(II) spin-crossover nanoparticles prepared by the reverse micelle technique by using the non-ionic surfactant Lauropal (Ifralan D0205) from the polyoxyethylenic family. By changing the surfactant/water ratio, the size of the particles of [Fe(NH2-trz)3]Br2.3H2O (with NH2trz=4-amino-1,2,4-triazole) can be controlled. On the macroscopic scale this complex exhibits cooperative thermal spin crossovers at 305 and 320 K. We find that when the size is reduced down to 50 nm, the spin transition becomes gradual and no hysteresis can be detected. For our data it seems that the critical size, for which the existence of a thermal hysteresis can be detected, is around 50 nm. Interestingly, the change of the particle size induces almost no change in the temperature of the thermal spin transition. A systematic determination of coherent domain size carried out on the nanoparticles by powder X-ray diffraction indicates that at approximately 30 nm individual particles consist of one coherent domain.

Directed laser processing of compacted powder mixtures Al2O3-TiO2-Y2O3

Directory of Open Access Journals (Sweden)

Vlasova M.

2013-01-01

Full Text Available The phase formation, microstructure and surface texture of laser treated ternary powder mixtures of Al2O3-TiO2-Y2O3 had been studied. Rapid high temperature heating and subsequent rapid cooling due to the directed movement of the laser beam forms concave ceramic tracks. Phase composition and microstructure of the tracks depends on the Al2O3 content and the TiO2/Y2O3 ratio of the initial mixtures. The main phases observed are Y3Al5O12, Y2Ti2O7, Al2O3 and Al2TiO5. Due to the temperature gradient in the heating zone, complex layered structures are formed. The tracks consist of three main layers: a thin surface layer, a layer of crystallization products of eutectic alloys, and a lower sintered layer. The thickness of the crystallization layer and the shrinkage of the irradiation zone depend on the amount of Y3Al5O12 and Al2O3 crystallized from the melt.

A feasibility study of the preparation of (U,Gd)3O8 solid solutions by thermal decomposition of co-precipitated carbonate mixtures

International Nuclear Information System (INIS)

Ravindran, P.V.; Rajagopalan, K.V.; Mathur, K.P.

1998-01-01

Co-precipitation from equimolar nitrate solutions of uranium (VI) and gadolinium has been used to obtain a mixture of (NH 4 ) 4 UO 2 (CO 3 ) 3 and Gd 2 (CO 3 ) 3 .3H 2 O at a pre-determined composition. Simultaneous measurements by TG, DTA and evolved gas analysis (EGA) showed that a calcination temperature of 700 C was necessary to decompose the carbonate completely to oxides. X-ray diffraction data indicated that a solid solution of Gd 2 O 3 in U 3 O 8 cannot be obtained by heating the carbonate mixtures up to 800 C in inert atmospheres. (orig.)

Effect of Water Content on Properties of Homogeneous [bmim]Fe(IIICl4–H2O Mixtures and Their Application in Oxidative Absorption of H2S

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Jianhong Wang

2018-01-01

Full Text Available The potential of 1-butyl-3-methylimidazolium tetrachloroferrate ([bmim]Fe(IIICl4 for replacing an iron(III chelate catalytic solution in the catalytic oxidation of H2S is attributed to its no side reaction and no degradation of the chelating agent. The catalytic oxidation product of water in non-aqueous [bmim]Fe(IIICl4 possibly has an influence on the oxidative absorption of H2S. Water and hydrophobic [bmim]Fe(IIICl4 mixtures at water volume percents from 40% to 70% formed separate phases after srirring, without affecting the oxidative absorption of hydrogen sulfide. Then, studies on the properties of homogeneous [bmim]Fe(IIICl4–H2O mixtures at water volume percents in the range of 5.88–30% and above 80% reveal that these mixtures are both Brønsted and Lewis acids at vol % (H2O ≤ 30%, and only Lewis acids at vol % (H2O ≥ 80%. Raman spectra showed that [bmim]Fe(IIICl4 was the dominating species at vol % (H2O ≤ 30%, in contrast, [bmim]Fe(IIICl4 decomposed into FeCl3·2H2O and [bmim]Cl at vol % (H2O ≥ 80%. Further research on oxidative absorption of H2S by homogeneous [bmim]Fe(IIICl4–H2O mixtures demonstrated that [bmim]Fe(IIICl4 was reduced by H2S to [bmim]Fe(IICl4H and FeCl3·2H2O was reduced to FeCl2, at the same time, H2S was oxidized to S8. In addition, the decrease in acidity caused by increasing the water content increased the weight percent of absorbed H2S, and decreased volatile HCl emissions. However, it is difficult to prevent the suspended S8 generated at vol % (H2O ≥ 80% from the formation of sulfur blockage. Therefore, oxidative absorption of H2S by [bmim]Fe(IIICl4–H2O mixtures is feasible at vol % (H2O < 80% without sulfur blockage.

Effects of pH and H2O2 on ammonia, nitrite, and nitrate transformations during UV254nm irradiation: Implications to nitrogen removal and analysis.

Science.gov (United States)

Wang, Junli; Song, Mingrui; Chen, Baiyang; Wang, Lei; Zhu, Rongshu

2017-10-01

In order to achieve better removal and analyses of three dissolved inorganic nitrogen (DIN) species via ultraviolet-activated hydrogen peroxide (UV/H 2 O 2 ) process, this study systematically investigated the rates of photo-oxidations of ammonia/ammonium (NH 3 /NH 4 + ) and nitrite (NO 2 - ) as well as the photo-reduction of nitrate (NO 3 - ) at varying pH and H 2 O 2 conditions. The results showed that the mass balances of nitrogen were maintained along irradiation despite of interconversions of DIN species, suggesting that no nitrogen gas (N 2 ) or other nitrogen-containing compound was formed. NH 3 was more reactive than NH 4 + with hydroxyl radical (OH), and by a stepwise H 2 O 2 addition method NH 3 /NH 4 + can be completely converted to NO x - ; NO 2 - underwent rapid oxidation to form NO 3 - when H 2 O 2 was present, suggesting that it is an intermediate compound linking NH 3 /NH 4 + and NO 3 - ; but once H 2 O 2 was depleted, NO 3 - can be gradually photo-reduced back to NO 2 - at high pH conditions. Other than H 2 O 2 , the transformation kinetics of DINs were all dependent on pH, but to varying aspects and extents: the NH 3 photo-oxidation favored a pH of 10.3, which fell within the pK a values of NH 4 + (9.24) and H 2 O 2 (11.6); the NO 3 - photo-reduction increased with increasing pH provided that it exceeds the pK a of peroxynitrous acid (6.8); while the NO 2 - photo-oxidation remained stable unless the pH neared the pK a of H 2 O 2 (11.6). The study thereby demonstrates a picture of the evolutions of DIN species together during UV/H 2 O 2 irradiation process, and for the first time presents a method to achieve complete conversion of NH 4 + to NO 3 - with UV/H 2 O 2 process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Order-disorder phase transition in the peroxidovanadium complex NH4[VO(O2)2(NH3)].

Science.gov (United States)

Schwendt, Peter; Gyepes, Róbert; Chrappová, Jana; Němec, Ivan; Vaněk, Přemysl

2018-07-05

Complex NH 4 [VO(O 2 ) 2 (NH 3 )] (1) undergoes an order-disorder phase transition at T c ~258K. This transition is accompanied by change in the space group of the orthorhombic lattice and also by significant structural rearrangements of the constituent molecules, which are pertinent mostly to their NH 4 + ions and their ammonia ligands. The low-temperature solid state IR and Raman spectra of 1 were corroborated by solid-state computations that employed Gaussian functions as the basis set. Results of these computations yielded excellent agreement with experimental data. On the curves of temperature dependence of vibrational modes, the phase transition is expressed by an abrupt change of the slope above T c . Copyright © 2018 Elsevier B.V. All rights reserved.

First principles study of NH3 molecular adsorption on LiH (100) surfaces

International Nuclear Information System (INIS)

Lu Xiaoxia; Chen Yuhong; Dong Xiao

2012-01-01

The adsorption of NH 3 on LiH (100) crystal surfaces was studied by first principles method. The preferred adsorption sites, adsorption energy, dissociation energy and electronic structure of the LiH (100)/NH 3 systems were calculated separately. It is found that chemical adsorption happened mainly when NH 3 molecules are on the LiH (100) crystal surfaces. When NH 3 is adsorbed on the Li top site, NH 2 is formed on the LiH (100) crystal surfaces after loss of H atom, the calculated adsorption energy, 0.511 eV, belongs to strong chemical adsorption, then the interaction is strongest. The interaction between NH 2 and the neighboring Li, H are ionic. The covalent bonds are formed between N and H atoms in NH 2 . One H 2 molecule is formed by another H atom in NH 3 and H atom from LiH (100) crystal sur- faces. The covalent bonds are formed between H and H atoms in H 2 . (authors)

Nanostructured TiO2/CH3NH3PbI3 heterojunction solar cells employing spiro-OMeTAD/Co-complex as hole-transporting material

KAUST Repository

Noh, Jun Hong

2013-01-01

For using 2,2′,7,7′-tetrakis(N,N′-di-p- methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) as a hole conductor in solar cells, it is necessary to improve its charge-transport properties through electrochemical doping. With the aim of fabricating efficient mesoscopic TiO2/CH3NH3PbI3 heterojunction solar cells, we used tris[2-(1H-pyrazol-1-yl)-4-tert- butylpyridine)cobalt(iii) tris(bis(trifluoromethylsulfonyl) imide)] (FK209) as a p-dopant for spiro-OMeTAD. The mixture of spiro-OMeTAD, FK209, lithium bis(trifluoromethylsulfonyl)imide (Li-TFSI), and 4-tert-butylpyridine (TBP) exhibited significantly higher performance than mixtures of pristine spiro-OMeTAD, spiro-OMeTAD, and FK209, and spiro-OMeTAD, Li-TFSI, and TBP. Such a synergistic effect between the Co-complex and Li-TFSI in conjunction with spiro-OMeTAD effectively improved the power conversion efficiency (PCE) of the fabricated solar cells. As a result, we achieved PCE of 10.4%, measured under standard solar conditions (AM 1.5G, 100 mW cm-2). © 2013 The Royal Society of Chemistry.

Modeling Phase Equilibria for Acid Gas Mixtures Using the CPA Equation of State. I. Mixtures with H2S

DEFF Research Database (Denmark)

Tsivintzelis, Ioannis; Kontogeorgis, Georgios; Michelsen, Michael Locht

2010-01-01

(water, methanol, and glycols) are modeled assuming presence or not of cross-association interactions. Such interactions are accounted for using either a combining rule or a cross-solvation energy obtained from spectroscopic data. Using the parameters obtained from the binary systems, one ternary......The Cubic-Plus-Association (CPA) equation of state is applied to a large variety of mixtures containing H2S, which are of interest in the oil and gas industry. Binary H2S mixtures with alkanes, CO2, water, methanol, and glycols are first considered. The interactions of H2S with polar compounds...... and three quaternary mixtures are considered. It is shown that overall excellent correlation for binary, mixtures and satisfactory prediction results for multicomponent systems are obtained. There are significant differences between the various modeling approaches and the best results are obtained when...

Dehydration of Sugar Mixture to HMF and Furfural over SO42-/ZrO2-TiO2 Catalyst

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Junhua Zhang

2014-05-01

Full Text Available A series of sulfated zirconia-titanium dioxide (SO42-/ZrO2-TiO2 catalysts with different Zr-Ti molar ratios were prepared by a precipitation and impregnation method and characterized by ammonia adsorption/ temperature programmed desorption (NH3-TPD, X-ray diffraction (XRD, and X-ray photoelectron spectroscopy (XPS techniques. The catalysts were used in the catalytic conversion of a sugar mixture (glucose and xylose to 5-hydroxymethylfurfural and furfural in a water/n-butanol reaction system. An optimized yield of 26.0 mol% for 5-hydroxymethylfurfural and 47.5 mol% for furfural was obtained within 2 h at 170 °C over the SO42-/ZrO2-TiO2 catalyst with a Zr-Al molar ratio of 7:3. Catalysts with higher acidity and moderate basicity were more favorable for the formation of the target product.

Reactivity of Surface Nitrates in H2-Assisted SCR of NOx Over Ag/Al2O3 Catalyst

DEFF Research Database (Denmark)

Sadokhina, N. A.; Doronkin, Dmitry E.; Baeva, G. N.

2013-01-01

The role of nitrate ad-species in H2-assisted SCR over Ag/Al2O3 was compared in NH3-SCR and n-C6H14-SCR processes. It was found that nitrates could be reduced by NH3 or n-C6H14 at similar rates with H2 co-feeding which indicates a common rate-limiting step. However, contributions of surface nitrate...... reduction to the overall NH3-SCR or n-C6H14-SCR are different as revealed by comparing the rates of nitrate reduction with the rates of steady-state processes. The rate of the steady-state n-C6H14-SCR is virtually identical to the rate of surface nitrate reduction suggesting a significant contribution...... of the surface nitrates reduction to the overall n-C6H14-SCR process. On the other hand, the steady-state rate of NH3-SCR is by ~15 times higher, which indicates that the reduction of surface nitrates plays a marginal role in the overall NH3-SCR....

Binary Mixtures of Nonyl Phenol with Alkyl Substituted Anilines as Corrosion Inhibitors for Mild Steel in Acidic Medium

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H. S. Shukla

2012-01-01

Full Text Available The present study deals with the evaluation of the corrosion inhibition effectiveness of the two binary mixtures of nonyl phenol (NPH with 2, 4 dimethyl aniline (DMA and 2 ethyl aniline (EA at different concentration ratios (from 1:7 to 7:1 for mild steel in H2SO4 (pH=1 solution by weight loss and potentiodynamic polarization method. Corrosion inhibition ability of the compounds has been tested at different exposure periods (6 h to 24 h and at different temperatures (303 K to 333 K. The binary mixture of NPH and EA (at 7:1 concentration ratio has afforded maximum inhibition (IE% 93.5% at 6 h exposure period and at room temperature. The adsorption of both the inhibitors is found to accord with Temkin adsorption isotherm. Potentiodynamic polarization study reveals that the tested inhibitors are mixed type inhibitor and preferentially act on cathodic areas. Electrochemical impedance study suggests formation of an inhibition layer by the adsorption of the inhibitors on the metal surface. An adsorption model of the inhibitor molecules on the metal surface has been proposed after immersion test in the inhibited acid showed characteristic shift of N-H and O-H bond frequencies towards lower side compared to that of the respective pure samples which indicated the donation of electron pair through N and O atom of the inhibitor molecule in the surface adsorption phenomena. SEM study has revealed formation of semi globular inhibitor products on the metal surface. The comparisons of the protection efficiencies of these compounds according to their relative electron density on the adsorption centre and projected molecular area of the inhibitor molecules have been made.

H2 assisted NH3-SCR over Ag/Al2O3 for automotive applications

DEFF Research Database (Denmark)

Fogel, Sebastian

-BEA can give a high NOx conversion in a broad temperature window without the need to dose H2 at higher temperatures. The aim of this study has been to investigate the combined Ag/Al2O3 and Fe-BEA catalyst system both at laboratory-scale and in full-scale enginebench testing. The catalysts were combined...... both in a sequential dual-bed layout and a dual-layer layout where the catalysts were coated on top of each other. The Ag/Al2O3 catalyst was also investigated with the aim of improving the sulphur tolerance and low-temperature activity by testing different alumina-supports. A large focus of this study...... the layers allowing diffusion of reaction intermediates between them. Ag/Al2O3 only and the combined Ag/Al2O3 – Fe-BEA systems were active during the transient NEDC. The NOx conversions were not very high which is related to the very low temperature of the NEDC and the lower than expected activity of the Ag...

(Vapour + liquid) equilibria for binary and ternary mixtures of 2-propanol, tetrahydropyran, and 2,2,4-trimethylpentane at P = 101.3 kPa

International Nuclear Information System (INIS)

Lin, Dun-Yi; Tu, Chein-Hsiun

2012-01-01

Highlights: ► We report the VLE data at P = 101.3 kPa involving a cyclic ether. ► The activity coefficients of mixtures were obtained from modified Raoult’s law. ► The VLE data were correlated by four liquid activity coefficient models. ► The ternary VLE data were predicted from binary parameters of the four models. - Abstract: (Vapour + liquid) equilibrium (VLE) at P = 101.3 kPa have been determined for a ternary system (2-propanol + tetrahydropyran + 2,2,4-trimethylpentane) and its constituent binary systems (2-propanol + tetrahydropyran, 2-propanol + 2,2,4-trimethylpentane), and (tetrahydropyran + 2,2,4-trimethylpentane). Analysis of VLE data reveals that two binary systems (2-propanol + tetrahydropyran) and (2-propanol + 2,2,4-trimethylpentane) have a minimum boiling azeotrope. No azeotrope was found for the ternary system. The activity coefficients of liquid mixtures were obtained from the modified Raoult’s law and were used to calculate the reduced excess molar Gibbs free energy (g E /RT). Thermodynamic consistency tests were performed for all VLE data using the Van Ness direct test for the binary systems and the test of McDermott–Ellis as modified by Wisniak and Tamir for the ternary system. The VLE data of the binary mixtures were correlated using the three-suffix Margules, Wilson, NRTL, and UNIQUAC activity-coefficient models. The models with their best-fitted interaction parameters of the binary systems were used to predict the ternary (vapour + liquid) equilibrium.

LPG and NH3 Sensing Properties of SnO2 Thick Film Resistors Prepared by Screen Printing Technique

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A. S. GARDE

2010-11-01

Full Text Available The gas sensing behavior of SnO2 thick film resistors deposited on alumina substrates has been investigated for LPG and NH3 gas. The standard screen printing technology was used to prepare the thick films. The films were fired at optimized temperature of 780 0C for 30 minutes. The material characterization was performed by XRD, SEM, FTIR, UV and EDAX for elemental analysis. IR spectroscopy analysis at 2949.26 cm-1 showed the peak assigned to the –Sn-H vibration due to the effect of hybridization i.e. sp3 and the sharp peak at 3734.31 cm-1 assigned to –Sn-OH stretching vibration due to hydrogen bonding. The variation of D.C electrical resistance of SnO2 film samples was measured in air as well as in LPG and NH3 gas atmosphere as a function of temperature. The SnO2 film samples show negative temperature coefficient of résistance. The SnO2 film samples showed the highest sensitivity to 600 ppm of LPG at 230 0C and NH3 at 370 0C. The effect of microstructure on sensitivity, response time and recovery time of the sensor in the presence of LPG and NH3 gases were studied and discussed.

NH3/O2 mixed gas plasmas alter the interaction of blood components with stainless steel.

Science.gov (United States)

Chen, Meng; Zamora, Paul O; Peña, Louis; Som, Prantika; Osaki, Shigemasa

2003-12-01

Stainless steel treated with a mixed gas plasma of NH(3) plus O(2) had chemical and biologic characteristics distinct from untreated stainless steel or stainless steel treated with NH(3) or O(2) plasmas used separately. NH(3)/O(2) plasmas deposited nitrogen as both -CN (organic) and -NO (nitrate, nitrite)--materials not found on untreated stainless steel--and the contact angle changed from 44 degrees to 23 degrees. Treatment of stainless steel (and titanium) resulted in surfaces with enhanced resistance to platelet and leukocyte attachment. A gas plasma of N(2)O/O(2) also was found to reduce platelet and leukocyte attachment, suggesting that these properties may be common to surfaces coated with oxynitrites (nitrides). Upon subcutaneous implantation, no inflammation, hemolysis, or untoward thrombosis was noted in the tissue surrounding the wafers treated with the NH(3)/O(2) plasmas, although the cellular density was considerably reduced by 2 weeks after implant. Collectively, the results suggest that NH(3)/O(2) plasmas impart a unique character to stainless steel that may be useful in the construction of medical devices. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 994-1000, 2003

Synthesis, structural characterization and ion-exchange behavior of a newly designed polyoxometalate, (Me2NH2)3(Mo12O40S)

International Nuclear Information System (INIS)

Chakraborty, Rajesh; Mondal, Biplab; Chattopadhyay, Pabitra

2015-01-01

A new ion-exchanger of chemical formula (Me 2 NH 2 ) 3 (Mo 12 O 40 S) (1) of the class of Keggin type polyoxometalate has been synthesized and characterized by single-crystal XRD. The crystal of 1 is rhombohedral, space group R-3 with cell dimensions, a = 16.504(18) Å, b = 16.504(18)Å (1) Å, c = 25.23(3) Å and α = 90.00°, β = 90.00°, γ = 120.00° and Z = 6. This material (1) is thermally and chemically stable even towards radiation. Its ion exchange capacity for alkali and alkaline earth metal ions has been studied. This material is useful to separate the short-lived daughter 90 Y from its long-lived parent 90 Sr in the equilibrium mixture at pH 6.0 with 1.0 % EDTA solution as an eluent. (author)

Effects of the addition of H{sub 2}O and NH{sub 4}OH in the electrical properties of thin films of Y{sub 2}O{sub 3} deposited by pyrolytic spray; Efectos de la adicion de H{sub 2}O y NH{sub 4}OH en las propiedades electricas de peliculas delgadas de Y{sub 2}O{sub 3} depositadas por rocio pirolitico

Energy Technology Data Exchange (ETDEWEB)

Herrera S, H.J.; Alarcon F, G.; Aguilar F, M. [CICATA-IPN, Legaria 694, Col. Irrigacion, 11500 Mexico D.F. (Mexico); Falcony, C. [CINVESTAV-IPN, 07000 Mexico D.F. (Mexico); Garcia H, M.; Guzman M, J. [IIM-UNAM, A.P. 70-360, 04510 Mexico D.F. (Mexico); Araiza I, J.J. [UAZ, 98060 Zacatecas (Mexico)

2005-07-01

In this work we studied the electrical properties of yttrium oxide thin films obtained by spray pyrolysis from Y(acac){sub 3} and N,N-DMF. The films were deposited on Si(100) substrates at temperatures of 400, 450, 500 and 550 C. The electrical characteristic of the films was improved when a mist of H{sub 2}O and/or NH{sub 4}0H was simultaneously added to the deposition system. Current and capacitance versus voltage measurements were obtained when the Y{sub 2}O{sub 3} films were integrated in MOS (Metal-Oxide-Semiconductor) structures. Y{sub 2}O{sub 3} films with a dielectric constant up to 15 were obtained. The films can stand electric fields up to 2 MV/cm. An interface state density in the range of 10{sup 10}-10{sup 11} cm{sup -2} eV{sup -1} was measured at midgap from the high and low frequency capacitance measurements. (Author)

Modeling phase equilibria for acid gas mixtures using the CPA equation of state. Part II: Binary mixtures with CO2

DEFF Research Database (Denmark)

Tsivintzelis, Ioannis; Kontogeorgis, Georgios; Michelsen, Michael Locht

2011-01-01

In Part I of this series of articles, the study of H2S mixtures has been presented with CPA. In this study the phase behavior of CO2 containing mixtures is modeled. Binary mixtures with water, alcohols, glycols and hydrocarbons are investigated. Both phase equilibria (vapor–liquid and liquid–liqu...

Treatment for GaSb surfaces using a sulphur blended (NH4)2S/(NH4)2SO4 solution

International Nuclear Information System (INIS)

Murape, D.M.; Eassa, N.; Neethling, J.H.; Betz, R.; Coetsee, E.; Swart, H.C.; Botha, J.R.; Venter, A.

2012-01-01

A sulphur based chemical, [(NH 4 ) 2 S/(NH 4 ) 2 SO 4 ] to which S has been added, not previously reported for the treatment of (1 0 0) n-GaSb surfaces, is introduced and benchmarked against the commonly used passivants Na 2 S·9H 2 O and (NH 4 ) 2 S. The surfaces of the treated material were studied by scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). It has been found that the native oxides present on the GaSb surface are more effectively removed when treated with ([(NH 4 ) 2 S/(NH 4 ) 2 SO 4 ] + S) than with (NH 4 ) 2 S or Na 2 S·9H 2 O, as evidenced by the ratio of the O 506eV to Sb 457eV AES peaks. XPS results reveal that Sb 2 S 3 /Sb 2 S 5 “replaces” Sb 2 O 3 /Sb 2 O 5 , suggesting that sulphur atoms substitute oxygen atoms in Sb 2 O 3 /Sb 2 O 5 to form Sb-S. It seems sulphurization only partially removes Ga 2 O 3 . Treatment with ([(NH 4 ) 2 S/(NH 4 ) 2 SO 4 ] + S) also results in a noteworthy improvement in the current-voltage (I-V) characteristics of Au/n-GaSb Schottky contacts compared to those fabricated on as-received material.

Structures, energetics, vibrational spectra of NH4+ (H2O)(n=4,6) clusters: Ab initio calculations and first principles molecular dynamics simulations.

Science.gov (United States)

Karthikeyan, S; Singh, Jiten N; Park, Mina; Kumar, Rajesh; Kim, Kwang S

2008-06-28

Important structural isomers of NH(4) (+)(H(2)O)(n=4,6) have been studied by using density functional theory, Moller-Plesset second order perturbation theory, and coupled-cluster theory with single, double, and perturbative triple excitations [CCSD(T)]. The zero-point energy (ZPE) correction to the complete basis set limit of the CCSD(T) binding energies and free energies is necessary to identify the low energy structures for NH(4) (+)(H(2)O)(n=4,6) because otherwise wrong structures could be assigned for the most probable structures. For NH(4) (+)(H(2)O)(6), the cage-type structure, which is more stable than the previously reported open structure before the ZPE correction, turns out to be less stable after the ZPE correction. In first principles Car-Parrinello molecular dynamics simulations around 100 K, the combined power spectrum of three lowest energy isomers of NH(4) (+)(H(2)O)(4) and two lowest energy isomers of NH(4) (+)(H(2)O)(6) explains each experimental IR spectrum.

A Highly Selective Room Temperature NH3 Gas Sensor based on Nanocrystalline a-Fe2O3

Directory of Open Access Journals (Sweden)

Priyanka A. PATIL

2017-05-01

Full Text Available Nanocrystalline a-Fe2O3 powder was synthesized by simple, inexpensive sol-gel method. The obtained powder was calcined at 700 0C in air atmosphere for 2 hours. The structural and morphological properties of calcined powder were studied by X-ray diffraction (XRD and Field Emission Scanning Electron Microscopy (FESEM respectively. Thermal properties of dried gel were studied by Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA/DSC. The XRD pattern of the powder confirmed the a-Fe2O3 (hematite phase of iron oxide with average crystalline size of 30.87 nm calculated from Scherrer equation. The FESEM images showed uniform wormlike morphology of a-Fe2O3 powder. TGA result indicated that a-Fe2O3 is thermodynamically stable. Room temperature NH3 sensing characteristics of a-Fe2O3 were studied for various concentration levels (250-2500 ppm of NH3 at various humid conditions. The sensor based on a-Fe2O3 exhibited good selectivity and excellent sensitivity (S=92 towards 1000 ppm of NH3 with quick response of 4 sec and fast recovery of 9 sec. Room temperature sensing mechanism is also discussed.

Far-UV, visible, and near-IR reflectance spectra of frosts of H2O, CO2, NH3 and SO2

Science.gov (United States)

Hapke, B.; Wells, E.; Wagner, J.; Partlow, W.

1981-01-01

Measurements in the 0.1-2.5 micron range are presented for the reflectance spectra of the frosts of several volatiles pertinent to the study of comet nuclei. The frost spectra have distinctive features permitting their identification by spectroscopic reflectance remote sensing, notably in the far UV. It is found that: (1) H2O has a minimum at 0.16 microns and a maximum at 0.13 microns; (2) CO2 has minima near 0.21, 0.18 and 0.125 microns, with maxima at 0.19, 0.135 and 0.120 microns; (3) NH3 is bright at wavelengths longer than 0.21 microns, where reflectance drops to a value of only a few per cent at shorter wavelengths; (4) SO2 has a sharp drop at 0.32 microns, with a minimum at 0.18 microns and a maximum at 0.13 microns. The features in the frost spectra largely correspond to absorption line bands in the gas phase.

Ferroelastoelectric phase transition in (NH4)2CuCl4·2H2O single crystal

International Nuclear Information System (INIS)

Tylczyński, Zbigniew; Wiesner, Maciej

2015-01-01

The (NH 4 ) 2 CuCl 4 ·2H 2 O crystal exhibits anomalous thermal, piezoelectric, dielectric and elastic properties in the vicinity of the ferroelastoelectric phase transition at T C  = 200 K. Macroscopic order parameter is the h 36 component of the spontaneous piezoelectric tensor connecting polarisation P 3 and strain η 6 . The temperature change in h 36 component was proportional to (T C  − T) α , where α = 0.58 ± 0.05. Close to T C changes in dielectric permittivity were negligible. High value of ac conductivity in the high-temperature phase results from protons jumping between disordered ions NH 4 + and between molecules of crystallisation water. Only longitudinal ultrasonic waves exhibited an abrupt change upon the phase transition. The relaxation time of the order parameter was determined from anomalous changes in attenuation of the longitudinal waves. - Highlights: • Low-temperature phase shows higher-order ferroicity: ferroelastoelectricity. • Temperature change of spontaneous piezoelectricity was studied in the ordered phase. • Dispersion of complex dielectric constant was investigated in wide temperature range. • At high-temperature phase ac conductivity is caused by proton jumps. • Anomalies of ultrasonic waves at T C were analysed using phenomenological theory

A study of the accelerated zircaloy-4 oxidation reaction with H2O/H2 mixture gas

International Nuclear Information System (INIS)

Kim, Y. S.; Cho, I. J.

2001-01-01

A study of the Zircaloy-4 reaction with H 2 O/H 2 mixture gas is carried out by using TGA (Thermo Gravimetric Apparatus) to estimate the hydrogen embrittlement which can possibly cause catastrophic nuclear fuel rod failure. Reaction rates are measured as a function of H 2 /H 2 O. In the experiments reaction temperature is set at 500 .deg. C and total pressure of the mixture gas is maintained at 1 atm. Experimental results reveal that hydriding and oxidation reaction are competing. In early stage, hydriding kinetics is faster than oxidation, however, oxidant in H 2 O forms oxide on the surface as steam environment is maintained, thus, this growing oxide begins to protect the zirconium base metal against hydrogen permeation. In this second stage, the total kinetic rate follows enhanced oxidation kinetics. In the final stage, it is observed that the oxide is broken down and massive hydriding takes place through the mechanical defects in the oxide, whose kinetics is similar to pure hydriding kinetics. These results are confirmed by SEM and EDX analysis along with hydrogen concentration measurements

Cs2SO4-Pr2(SO4)3-H2O and NiSO4-Pr2(SO4)3-H2O systems at 75 deg C

International Nuclear Information System (INIS)

Onishchenko, M.K.; Skorikov, V.M.; Shevchuk, V.G.; AN SSSR, Moscow. Inst. Obshchej i Neorganicheskoj Khimii)

1979-01-01

To investigate physico-chemical properties of equilibrium saturated solutions and to elucidate the chemical changes under way, the aqueous systems of cesium, nickel and praseodymium (3) sulfates are studied. The method of isothermal saturation of salts at 75 deg C is used. It has been found that in the system Cs 2 SO 4 -Pr 2 (SO 4 ) 3 -H 2 O in a wide concentration range the soluble binary salt Cs 2 SO 4 xPr 2 (SO 4 ) 3 csytallizes in a congruent way. For the system NiSO 4 -Pr 2 (SO 4 ) 3 -H 2 O a solubility curve of the eutonic type is obtained, there being no chemical interaction between the components. The solubility isotherms for the system are given

Synthesis and study of the triphosphate salt LiSr2P3O10·8H2O

International Nuclear Information System (INIS)

Sotnikova-Yuzhik, V.A.; Peslyak, G.V.

1995-01-01

Lithium triphosphate interaction with strontium nitrate in aqueous solution at 0.3 mole% concentration and 20 deg C is studied. Formation of crystal hydrate LiSr 2 P 3 O 10 ·8H 2 O and amorphous phase of variable composition Li 2,5-0,5x P 3 O 10 ·6H 2 O (0.20≤x≤0.55) is determined. Data on the stability of binary lithium-strontium triphosphate at storage, sequence of chemical and phase transitions under heating are obtained. 5 refs., 4 figs., 3 tabs

Stopped-Flow Spectrophotometric Study of the Kinetics and Mechanism of CO2 Uptake by cis-[Cr(C2O4(BaraNH2(OH22]+ Cation and the Acid-Catalyzed Decomposition of cis-[Cr(C2O4(BaraNH2OCO2]− Anion in Aqueous Solution

Directory of Open Access Journals (Sweden)

Lech Chmurzyński

2011-09-01

Full Text Available The kinetics of CO2 uptake by the cis-[Cr(C2O4(BaraNH2(OH22]+ complex cation and the acid hydrolysis of the cis-[Cr(C2O4(BaraNH2OCO2]− complex anion (where BaraNH2 denotes methyl 3-amino-2,3-dideoxy-b-D-arabino-hexopyranoside were studied using the stopped-flow technique. The reactions under study were investigated in aqueous solution in the 288–308 K temperature range. In the case of the reaction between CO2 and cis-[Cr(C2O4(BaraNH2(OH22]+ cation variable pH values (6.82–8.91 and the constant ionic strength of solution (H+, Na+, ClO4− = 1.0 were used. Carbon dioxide was generated by the reaction between sodium pyruvate and hydrogen peroxide. The acid hydrolysis of cis-[Cr(C2O4(BaraNH2OCO2]− was investigated for varying concentrations of H+ ions (0.01–2.7 M. The obtained results enabled the determination of the number of steps of the studied reactions. Based on the kinetic equations, rate constants were determined for each step. Finally, mechanisms for both reactions were proposed and discussed. Based on the obtained results it was concluded that the carboxylation (CO2 uptake reactions of cis-[Cr(C2O4(BaraNH2(OH22]+ and the decarboxylation (acid hydrolysis of the cis-[Cr(C2O4(BaraNH2OCO2]− are the opposite of each other.

In situ DRIFTS investigation of NH3-SCR reaction over CeO2/zirconium phosphate catalyst

Science.gov (United States)

Zhang, Qiulin; Fan, Jie; Ning, Ping; Song, Zhongxian; Liu, Xin; Wang, Lanying; Wang, Jing; Wang, Huimin; Long, Kaixian

2018-03-01

A series of ceria modified zirconium phosphate catalysts were synthesized for selective catalytic reduction of NO with ammonia (NH3-SCR). Over 98% NOx conversion and 98% N2 selectivity were obtained by the CeO2/ZrP catalyst with 20 wt.% CeO2 loading at 250-425 °C. The interaction between CeO2 and zirconium phosphate enhanced the redox abilities and surface acidities of the catalysts, resulting in the improvement of NH3-SCR activity. The in situ DRIFTS results indicated that the NH3-SCR reaction over the catalysts followed both Eley-Rideal and Langmuir-Hinshelwood mechanisms. The amide (sbnd NH2) groups and the NH4+ bonded to Brønsted acid sites were the important intermediates of Eley-Rideal mechanism.

REMEDIATION OF TEXTILE DYES MIXTURES USING TIO2/VIS PHOTOCATALYSIS AND FENTON FE2+/H2O2

Directory of Open Access Journals (Sweden)

P. M. Andrade

2015-12-01

Full Text Available This study aimed to use the following treatment technology: TiO2 photocatalysis and Fenton reaction for the remediation of mixture of textile dyes.  For the photocatalytic treatment it was obtained a reduction in color of 80% and Chemical Oxygen Demand of 60% using for this 600 mg L-1 of TiO2, 1500  mL min-1 recirculation flow, temperature 40 oC/45 oC and pH = 6.3 for 60 minutes of treatment. By Fenton reaction it was reached color reduction at 95% and Chemical Oxygen Demand reduction at 75% employing 60 mg L-1 H2O2, 50 mg L-1 de Fe2+ and pH = 4.0 for 62 minutes of treatment.