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Sample records for acid vapor hno3

  1. Passive sampler for measurements of atmospheric nitric acid vapor (HNO3) concentrations.

    PubMed

    Bytnerowicz, A; Padgett, P E; Arbaugh, M J; Parker, D R; Jones, D P

    2001-12-01

    Nitric acid (HNO3) vapor is an important nitrogenous air pollutant responsible for increasing saturation of forests with nitrogen and direct injury to plants. The USDA Forest Service and University of California researchers have developed a simple and inexpensive passive sampler for monitoring air concentrations of HNO3. Nitric acid is selectively absorbed on 47-mm Nylasorb nylon filters with no interference from particulate NO3-. Concentrations determined with the passive samplers closely corresponded with those measured with the co-located honeycomb annular denuder systems. The PVC protective caps of standardized dimensions protect nylon filters from rain and wind and allow for reliable measurements of ambient HNO3 concentrations. The described samplers have been successfully used in Sequoia National Park, the San Bernardino Mountains, and on Mammoth Mountain in California.

  2. Reactions between Criegee Intermediates and the Inorganic Acids HCl and HNO3 : Kinetics and Atmospheric Implications.

    PubMed

    Foreman, Elizabeth S; Kapnas, Kara M; Murray, Craig

    2016-08-22

    Criegee intermediates (CIs) are a class of reactive radicals that are thought to play a key role in atmospheric chemistry through reactions with trace species that can lead to aerosol particle formation. Recent work has suggested that water vapor is likely to be the dominant sink for some CIs, although reactions with trace species that are sufficiently rapid can be locally competitive. Herein, we use broadband transient absorption spectroscopy to measure rate constants for the reactions of the simplest CI, CH2 OO, with two inorganic acids, HCl and HNO3 , both of which are present in polluted urban atmospheres. Both reactions are fast; at 295 K, the reactions of CH2 OO with HCl and HNO3 have rate constants of 4.6×10(-11)  cm(3)  s(-1) and 5.4×10(-10)  cm(3)  s(-1) , respectively. Complementary quantum-chemical calculations show that these reactions form substituted hydroperoxides with no energy barrier. The results suggest that reactions of CIs with HNO3 in particular are likely to be competitive with those with water vapor in polluted urban areas under conditions of modest relative humidity.

  3. Nucleation of Mixed Nitric Acid-Water Ice Nanoparticles in Molecular Beams that Starts with a HNO3 Molecule.

    PubMed

    Lengyel, Jozef; Pysanenko, Andriy; Kočišek, Jaroslav; Poterya, Viktoriya; Pradzynski, Christoph C; Zeuch, Thomas; Slavíček, Petr; Fárník, Michal

    2012-11-01

    Mixed (HNO3)m(H2O)n clusters generated in supersonic expansion of nitric acid vapor are investigated in two different experiments, (1) time-of-flight mass spectrometry after electron ionization and (2) Na doping and photoionization. This combination of complementary methods reveals that only clusters containing at least one acid molecule are generated, that is, the acid molecule serves as the nucleation center in the expansion. The experiments also suggest that at least four water molecules are needed for HNO3 acidic dissociation. The clusters are undoubtedly generated, as proved by electron ionization; however, they are not detected by the Na doping due to a fast charge-transfer reaction between the Na atom and HNO3. This points to limitations of the Na doping recently advocated as a general method for atmospheric aerosol detection. On the other hand, the combination of the two methods introduces a tool for detecting molecules with sizable electron affinity in clusters.

  4. Optical detection of concentrations for mixed acid: HF and HNO3

    NASA Astrophysics Data System (ADS)

    Kang, Gumin; Kim, Kyoungsik

    2009-02-01

    Mixed acid, which consist of HF and HNO3, is used as a good etchant for silicon dioxide in the wet etching and pickling process of stainless steel. The optical detection of concentration for such mixed acids is crucial to optimize and cut costs in the manufacturing process. Optical detection in the IR regime has been utilized to measure the concentration of the mixed acid for HF and HNO3, because that has several strong absorption peaks, which is contributed by vibrational mode of each acid molecular in this spectrum. In this research, we observed the concentrations of mixed acid to consist of HF and HNO3, as we measured the absorption intensity of OH- stretch and NO3 - stretch band by optical spectroscopy. The concentration range of HF over 1.5-3 wt% and that of HNO3 over 2-10 wt% were studied in room temperature.

  5. Laboratory Evaluation of the Effect of HNO3 Uptake on Frost Point Hygrometer Measurement of Water Vapor under UT/LS Conditions

    NASA Astrophysics Data System (ADS)

    Thornberry, T.; Gierczak, T.; Gao, R.; Voemel, H.; Watts, L.; Burkholder, J. B.; Fahey, D. W.

    2010-12-01

    Chilled mirror hygrometers (CMH) are widely used to measure water vapor in the troposphere and lower stratosphere from balloon-borne sondes. Systematic discrepancies among in situ water vapor instruments have been observed at low water vapor mixing ratios (< 5 ppm) in the upper troposphere and lower stratosphere (UT/LS). Understanding the source of the measurement discrepancies is important for a more accurate and reliable determination of water vapor abundance in this region. We have conducted a laboratory study to investigate the potential interference of gas-phase nitric acid (HNO3) with the measurement of frost point temperature, and consequently the water vapor mixing ratio, determined by CMH under conditions representative of operation in the UT/LS. No detectable interference in the measured frost point temperature was found for HNO3 mixing ratios of up to 2 ppb for exposure times up to 150 minutes. HNO3 was observed to co-condense on the mirror frost, with the adsorbed mass increasing linearly with time at constant exposure levels. Over the duration of a typical balloon sonde ascent (90-120 min), the maximum accumulated HNO3 amounts were comparable to monolayer coverage of the geometric mirror surface area, which likely corresponds to small fractional coverage of the actual frost layer surface area. This small amount of co-condensed HNO3 is consistent with the observed lack of HNO3 interference in the frost point measurement because the CMH utilizes significant reductions (>10%) in surface reflectivity by the condensate for the determination of H2O.

  6. Nucleation of Mixed Nitric Acid-Water Ice Nanoparticles in Molecular Beams that Starts with a HNO3 Molecule.

    PubMed

    Lengyel, Jozef; Pysanenko, Andriy; Kočišek, Jaroslav; Poterya, Viktoriya; Pradzynski, Christoph C; Zeuch, Thomas; Slavíček, Petr; Fárník, Michal

    2012-11-01

    Mixed (HNO3)m(H2O)n clusters generated in supersonic expansion of nitric acid vapor are investigated in two different experiments, (1) time-of-flight mass spectrometry after electron ionization and (2) Na doping and photoionization. This combination of complementary methods reveals that only clusters containing at least one acid molecule are generated, that is, the acid molecule serves as the nucleation center in the expansion. The experiments also suggest that at least four water molecules are needed for HNO3 acidic dissociation. The clusters are undoubtedly generated, as proved by electron ionization; however, they are not detected by the Na doping due to a fast charge-transfer reaction between the Na atom and HNO3. This points to limitations of the Na doping recently advocated as a general method for atmospheric aerosol detection. On the other hand, the combination of the two methods introduces a tool for detecting molecules with sizable electron affinity in clusters. PMID:26296012

  7. Thermochemical Kinetics of H2O and HNO3 on crystalline Nitric Acid Hydrates (alpha-, beta-NAT, NAD) in the range 175-200 K

    NASA Astrophysics Data System (ADS)

    Rossi, Michel J.; Iannarelli, Riccardo

    2015-04-01

    The growth of NAT (Nitric Acid Trihydrate, HNO3x3H2O) and NAD (Nitric Acid Dihydrate, HNO3x2H2O) on an ice substrate, the evaporative lifetime of NAT and NAD as well as the interconversion of alpha- and beta-NAT competing with evaporation and growth under UT/LS conditions depends on the interfacial kinetics of H2O and HNO3 vapor on the condensed phase. Despite the existence of some literature results we have embarked on a systematic investigation of the kinetics using a multidiagnostic experimental approach enabled by the simultaneous observation of both the gas (residual gas mass spectrometry) as well as the condensed phase (FTIR absorption in transmission). We report on thermochemically consistent mass accommodation coefficients alpha and absolute evaporation rates Rev/molecule s-1cm-3 as a function of temperature which yields the corresponding vapor pressures of both H2O and HNO3 in equilibrium with the crystalline phases, hence the term thermochemical kinetics. These results have been obtained using a stirred flow reactor (SFR) using a macroscopic pure ice film of 1 micron or so thickness as a starting substrate mimicking atmospheric ice particles and are reported in a phase diagram specifically addressing UT (Upper Troposphere)/LS (Lower Stratosphere) conditions as far as temperature and partial pressures are concerned. The experiments have been performed either at steady-state flow conditions or in transient supersaturation using a pulsed solenoid valve in order to generate gas pulses whose decay were subsequently monitored in real time. Special attention has been given to the effect of the stainless-steel vessel walls in that Langmuir adsorption isotherms for H2O and HNO3 have been used to correct for wall-adsorption of both probe gases. Typically, the accommodation coefficients of H2O and HNO3 are similar throughout the temperature range whereas the rates of evaporation Rev of H2O are significantly larger than for HNO3 thus leading to the difference in

  8. Dissociation of strong acid revisited: X-ray photoelectron spectroscopy and molecular dynamics simulations of HNO3 in water

    SciTech Connect

    Lewis, Tanza; Winter, Berndt; Stern, Abraham C.; Baer, Marcel D.; Mundy, Christopher J.; Tobias, Douglas J.; Hemminger, J. C.

    2011-08-04

    Molecular-level insight into the dissociation of nitric acid in water is obtained from photoelectron X-ray spectroscopy and first-principles molecular dynamics (MD) simulations. Our combined studies reveal surprisingly abrupt changes in solvation configurations of undissociated nitric acid at approximately 4 M concentration. Experimentally, this is inferred from N1s binding energy shifts of HNO3(aq) as a function of concentration, and is associated with variations in the local electronic structure of the nitrogen atom. It also shows up as a discontinuity in the degree of dissociation as a function of concentration, determined here from the N1s photoelectron signal intensity, which can be separately quantified for undissociated HNO3(aq) and dissociated NO3-(aq). Intermolecular interactions within the nitric acid solution are discussed on the basis of MD simulations, which reveal that molecular HNO3 interacts remarkably weakly with solvating water molecules at low concentration; around 4 M there is a turnover to a more structured solvation shell, accompanied by an increase in hydrogen bonding between HNO3 and water. We suggest that the driving force behind the more structured solvent configuration of HNO3 is the overlap of nitric acid solvent shells that sets in around 4 M concentration. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  9. Vapor pressures of solid hydrates of nitric Acid: implications for polar stratospheric clouds.

    PubMed

    Worsnop, D R; Zahniser, M S; Fox, L E; Wofsy, S C

    1993-01-01

    Thermodynamic data are presented for hydrates of nitric acid: HNO(3).H(2)O, HNO(3).2H(2)O, HNO(3).3H(2)O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO(3).2H(2)O may be favored in polar stratospheric clouds over the slightly more stable HNO(3).3H(2)O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO(3).2H(2)O and HNO(3).3H(2)O. Vapor transfer from HNO(3).2H(2)O to HNO(3).3H(2)O could be a key step in the sedimentation of HNO(3), which plays an important role in the depletion of polar ozone. PMID:17757475

  10. Vapor pressures of solid hydrates of nitric Acid: implications for polar stratospheric clouds.

    PubMed

    Worsnop, D R; Zahniser, M S; Fox, L E; Wofsy, S C

    1993-01-01

    Thermodynamic data are presented for hydrates of nitric acid: HNO(3).H(2)O, HNO(3).2H(2)O, HNO(3).3H(2)O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO(3).2H(2)O may be favored in polar stratospheric clouds over the slightly more stable HNO(3).3H(2)O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO(3).2H(2)O and HNO(3).3H(2)O. Vapor transfer from HNO(3).2H(2)O to HNO(3).3H(2)O could be a key step in the sedimentation of HNO(3), which plays an important role in the depletion of polar ozone.

  11. Vapor pressures of solid hydrates of nitric acid - Implications for polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Worsnop, Douglas R.; Fox, Lewis E.; Zahniser, Mark S.; Wofsy, Steven C.

    1993-01-01

    Thermodynamic data are presented for hydrates of nitric acid: HNO3.H2O, HNO3.2H2O, HNO3.3H2O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO3.2H2O may be favored in polar stratospheric clouds over the slightly more stable HNO3.3H2O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO3.2H2O and HNO3.3H2O. Vapor transfer from HNO3.2H2O to HNO3.3H2O could be a key step in the sedimentation of HNO3, which plays an important role in the depletion of polar ozone.

  12. The influence of treatment temperature on the acidity of MWCNT oxidized by HNO 3 or a mixture of HNO 3/H 2SO 4

    NASA Astrophysics Data System (ADS)

    Saleh, Tawfik A.

    2011-06-01

    The nature of multi-walled carbon nanotubes (MWCNTs) varies with the change in oxidation conditions. In this work, the effect of treatment temperatures on the acidity of MWCNTs was studied. Oxidation was performed by refluxing the MWCNTs in nitric acid or mixtures of sulfuric acid and nitric acid at different temperatures. After oxidative treatment, a quantitative characterization of o-MWCNTs has been performed using acid-base titrations which show that the number of surface acidic functional groups increased by increasing the treatment temperatures. Energy dispersive X-ray (EDX) measurements show that the oxygen content increased with increasing treatment temperatures. Fourier transform infrared absorption spectroscopy (FTIR) was used for qualitative characterization. It has been demonstrated that the acidity is a function of the type of oxidizing agent used and the treatment temperatures. Due to the importance in attachment strategies and functionalization, this study adds to the global discussion of the possibility of controlling the MWCNTs' surface chemistry which plays a crucial role in determining its reactivity.

  13. Composition and freezing of aqueous H2SO4/HNO3 solutions under polar stratospheric conditions

    NASA Technical Reports Server (NTRS)

    Beyer, K. D.; Seago, S. W.; Chang, H. Y.; Molina, M. J.

    1994-01-01

    The results of laboratory investigations of the freezing behavior of aqueous acid solutions indicate that in the stratosphere H2SO/H2O aerosol droplets would not freeze at temperatures above the ice frost point in the absence of HNO3; however, in the presence of typical levels of HNO3 liquid sulfuric acid aerosols take up significant amounts of HNO3 and H2O vapors and freeze much more readily. This is a consequence of the very rapid change in composition of the liquid droplets as the temperature drops to within two to three degrees of the equilibrium temperature at which HNO3 and H2O vapors would co-condense to form a liquid solution. In the high latitude stratosphere this HNO3/H2O 'dew point' is typically around 192-194 K at 100 mbar.

  14. Redox reactions of Pu(IV) and Pu(III) in the presence of acetohydroxamic acid in HNO(3) solutions.

    PubMed

    Tkac, Peter; Precek, Martin; Paulenova, Alena

    2009-12-21

    The reduction of Pu(IV) in the presence of acetohydroxamic acid (HAHA) was monitored by vis-NIR spectroscopy. All experiments were performed under low HAHA/Pu(IV) ratios, where only the Pu(IV)-monoacetohydroxamate complex and Pu uncomplexed with HAHA were present in relevant concentrations. Time dependent concentrations of all absorbing species were resolved using molar extinction coefficients for Pu(IV), Pu(III), and the Pu(AHA)(3+) complex by deconvolution of spectra. From fitting of the experimental data by rate equations integrated by a numeric method three reactions were proposed to describe a mechanism responsible for the reduction and oxidation of plutonium in the presence of HAHA and HNO(3). Decomposition of Pu(AHA)(3+) follows a second order reaction mechanism with respect to its own concentration and leads to the formation of Pu(III). At low HAHA concentrations, a two-electron reduction of uncomplexed Pu(IV) with HAHA also occurs. Formed Pu(III) is unstable and slowly reoxidizes back to Pu(IV), which, at the point when all HAHA is decomposed, can be catalyzed by the presence of nitrous acid.

  15. Chemical Corrosion of Liquid-Phase Sintered SiC in Acidic/Alkaline Solutions Part 1. Corrosion in HNO3 Solution

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Zhang, Ming; He, Xinnong; Tang, Wenming

    2016-03-01

    The corrosion behavior of the liquid-phase sintered SiC (LPS-SiC) was studied by dipping in 3.53 mol/L HNO3 aqueous solution at room temperature and 70 °C, respectively. The weight loss, strength reduction and morphology evolution of the SiC specimens during corroding were revealed and also the chemical corrosion process and mechanism of the SiC specimens in the acidic solution were clarified. The results show that the corrosion of the LPS-SiC specimens in the HNO3 solution is selective. The SiC particles are almost free from corrosion, but the secondary phases of BaAl2Si2O8 (BAS) and Y2Si2O7 are corroded via an acid-alkali neutralization reaction. BAS has a higher corrosion rate than Y2Si2O7, resulting in the formation of the bamboo-leaf-like corrosion pits. As the SiC specimens etched in the HNO3 solution at room temperature for 75 days, about 80 μm thickness corrosion layer forms. The weight loss and bending strength reduction of the etched SiC specimens are 2.6 mg/cm2 and 52%, respectively. The corrosion of the SiC specimens is accelerated in the 70 °C HNO3 solution with a rate about five times bigger than that in the same corrosion medium at room temperature.

  16. Fast-response airborne in situ measurements of HNO3 during the Texas 2000 Air Quality Study

    NASA Astrophysics Data System (ADS)

    Neuman, J. A.; Huey, L. G.; Dissly, R. W.; Fehsenfeld, F. C.; Flocke, F.; Holecek, J. C.; Holloway, J. S.; Hübler, G.; Jakoubek, R.; Nicks, D. K.; Parrish, D. D.; Ryerson, T. B.; Sueper, D. T.; Weinheimer, A. J.

    2002-10-01

    Nitric acid (HNO3) was measured from an aircraft in the planetary boundary layer and free troposphere up to 7 km on 14 flights during the Texas Air Quality Study in August and September 2000. HNO3 mixing ratios were measured at 1 Hz using a fast-response chemical ionization mass spectrometer with SiF5- reagent ions. HNO3 measurement using this highly selective ion chemistry is insensitive to water vapor and is not degraded by interferences from other species. Rapid time response (1 s) was achieved using a heated Teflon inlet. In-flight standard addition calibrations from a HNO3 permeation source were used to determine the instrument sensitivity of 1.1 ± 0.1 ion counts pptv-1 s-1 over the duration of the study. Contributions to the HNO3 signal from instrument artifacts were accounted for by regularly performing in-flight instrument background checks, where HNO3 was removed from the ambient air sample by diverting the sampled air though a nylon wool scrubber. Measurement inaccuracy, which is determined from uncertainties in the standard addition calibrations, was ±10%. Measurement precision at low HNO3 levels was ±25 pptv (1σ) for the 1 Hz data and ±9 pptv for 10 s averages of the 1 s measurements. Coincident in situ measurements of other reactive nitrogen species are used to examine NOy partitioning and HNO3 formation during this month long measurement campaign. The sum of the individually measured reactive nitrogen species is shown to be in agreement with the measured NOy. HNO3 formation in plumes from electric utility power plants, urban areas, and petrochemical facilities was studied. The observed differences in the fractional contribution of HNO3 to NOy in plumes from different anthropogenic source types are discussed.

  17. Mass accommodation coefficient measurements for HNO3, HCl and N2O5 on water, ice and aqueous sulfuric acid droplet surfaces

    NASA Technical Reports Server (NTRS)

    Worsnop, Douglas; Zahniser, Mark; Kolb, Charles; Watson, Lyn; Vandoren, Jane; Jayne, John; Davidovits, Paul

    1988-01-01

    Preliminary results are reported of the direct measurement of accommodation coefficients for HNO3, N2O5 and HCl on water drops, aqueous sulfuric acid drops and ice particles. The heterogeneous chemistry of these species together with ClONO2 has been implicated in the ozone depletion observed in the Antarctic stratosphere during the spring in the last eight years. The most plausible chemical mechanism involves the removal of nitrogen oxide species via condensation on ice particles in polar stratospheric clouds resulting in a increase in the active chlorine species responsible for the ozone depletion. The observation of low NO2 and high ClO densities in the Antarctic stratosphere last summer appear to be consistent with such a mechanism.

  18. Spectroscopic study of HNO3 dissociation on ice.

    PubMed

    Marchand, Patrick; Marcotte, Guillaume; Ayotte, Patrick

    2012-12-13

    A detailed spectroscopic study of HNO(3):H(2)O binary amorphous mixtures, and of the adsorption of HNO(3) onto ice, is reported. Using a classical optics model, the extent of intermixing and of ionic dissociation of adsorbed HNO(3), which forms a strong acid with liquid water, is determined as a function of HNO(3) coverage and temperature. Even at temperatures as low as 45 K, where intermixing is limited to at most a few molecular layers at the interface, ionic dissociation of adsorbed HNO(3) is observed to be extensive. While some amount of molecularly adsorbed HNO(3) is observed at the surface of ice at 45 K, its ionic dissociation occurs irreversibly upon heating the ice substrate to 120 K. The molecularly adsorbed state of HNO(3) is not restored upon cooling, suggesting HNO(3) is a metastable entity at the surface of ice. Therefore, despite ionic dissociation of HNO(3) being thermodynamically favored, it appears to be kinetically inhibited at the surface of amorphous solid water at temperatures below 120 K.

  19. Heterogeneous kinetics of H2O, HNO3 and HCl on HNO3 hydrates (α-NAT, β-NAT, NAD) in the range 175-200 K

    NASA Astrophysics Data System (ADS)

    Iannarelli, Riccardo; Rossi, Michel J.

    2016-09-01

    Experiments on the title compounds have been performed using a multidiagnostic stirred-flow reactor (SFR) in which the gas phase as well as the condensed phase has been simultaneously investigated under stratospheric temperatures in the range 175-200 K. Wall interactions of the title compounds have been taken into account using Langmuir adsorption isotherms in order to close the mass balance between deposited and desorbed (recovered) compounds. Thin solid films at 1 µm typical thickness have been used as a proxy for atmospheric ice particles and have been deposited on a Si window of the cryostat, with the optical element being the only cold point in the deposition chamber. Fourier transform infrared (FTIR) absorption spectroscopy in transmission as well as partial and total pressure measurement using residual gas mass spectrometry (MS) and sensitive pressure gauges have been employed in order to monitor growth and evaporation processes as a function of temperature using both pulsed and continuous gas admission and monitoring under SFR conditions. Thin solid H2O ice films were used as the starting point throughout, with the initial spontaneous formation of α-NAT (nitric acid trihydrate) followed by the gradual transformation of α- to β-NAT at T > 185 K. Nitric acid dihydrate (NAD) was spontaneously formed at somewhat larger partial pressures of HNO3 deposited on pure H2O ice. In contrast to published reports, the formation of α-NAT proceeded without prior formation of an amorphous HNO3 / H2O layer and always resulted in β-NAT. For α- and β-NAT, the temperature-dependent accommodation coefficient α(H2O) and α(HNO3), the evaporation flux Jev(H2O) and Jev(HNO3) and the resulting saturation vapor pressure Peq(H2O) and Peq(HNO3) were measured and compared to binary phase diagrams of HNO3 / H2O in order to afford a thermochemical check of the kinetic parameters. The resulting kinetic and thermodynamic parameters of activation energies for evaporation (Eev) and

  20. Condensation of HNO3 and HCl in the winter polar stratospheres

    NASA Technical Reports Server (NTRS)

    Toon, Owen B.; Pinto, Joseph; Hamill, Patrick; Turco, Richard P.

    1986-01-01

    Nitric acid and hydrochloric acid vapors may condense in the winter polar stratospheres. Nitric acid clouds, unlike water ice clouds, would form at the temperatures at which polar stratospheric clouds (PSCs) are observed and would have optical depths of the magnitude observed suggesting that HNO3 is a dominant component of PSCs. ClO, N2O5 and ClNO3 may react on cloud particle surfaces yielding additional HNO3, HCl, and HOCL. In the vicinity of PSCs these reactions could deplete the stratosphere of photochemically active NO(x) species. The sedimentation of PSCs may remove these materials from the stratosphere. The loss of vapor phase NO(x) might allow halogen-based chemistry to create the ozone hole.

  1. Nucleation and growth of HNO3-3H2O particles in the polar stratosphere

    NASA Technical Reports Server (NTRS)

    Wofsy, Steven C.; Gobbi, Gian Paolo; Salawitch, Ross J.; Mcelroy, Michael B.

    1990-01-01

    Growth of nitric acid trihydrate (NAT) particles on background stratospheric aerosols is examined for an isolated air parcel cooled at a uniform rate. During the process of nucleation, the saturation ratio of HNO3 vapor reaches a maximum value between 2 and 15, corresponding to supercooling by 1-4 K. If cooling rates exceed 0.5-1 K/day, small particles of NAT are produced. A major fraction of the available condensation nuclei is activated and removal of HNO3 by gravitational settling is slow. If cooling rates are less than 0.5-1 K/day, the number of aerosols that nucleate is reduced, leading to differential growth of large NAT particles. Observations of 5 micron radius particles in clouds at temperatures above the water frost point may reflect condensation of NAT on ice particles that fall through a column of air as it is cooled. Rapid condensation of HNO3 on ice particles is promoted by the high supersaturation attained during nucleation and maintained during subsequent cooling. This process provides a mechanism for irreversible removal of HNO3.

  2. Laboratory studies of HNO3/H2O mixtures at low temperatures

    NASA Technical Reports Server (NTRS)

    Hanson, David; Mauersberger, Konrad

    1988-01-01

    The possibility of stratospheric HN3 condensing out of the gas-phase at low temperatures has become important in the chemical explanations of the rapid loss of Antarctic ozone in spring. Consequently, knowledge about the behavior of the vapor pressures of water and HNO3 over HNO3/water mixtures at stratospheric temperatures is needed to determine if HNO3 could condense, and by how much the HNO3 vapor pressure could be depressed. Laboratory investigations of vapor pressures above HNO3/water mixtures are described. Vapor pressures were initially measured over liquid and frozen bulk mixtures contained in a glass still which was attached to a stainless steel vacuum chamber. The total pressure in the chamber was monitored with a precision pressure sensor, and the vapor pressures of HNO3, water and impurities were analyzed with a mass spectrometer beam system. In a second set of experiments, vapor deposits were made to produce ice and the mono- and trihydrate of HNO3. Further data and conclusions are presented.

  3. Freezing temperatures of H2SO4/HNO3/H2O mixtures: Implications for polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Song, Naihui

    1994-01-01

    The freezing temperatures of H2SO4/HNO3/H2O mixtures were systematically documented. Nitric acid was found to affect freezing significantly. Measurements show that nitric acid can cause substantial supercooling over a broad composition range. However, some ternary compositions, like to those in polar stratospheric clouds (PSCs), have high freezing temperatures. The freezing of PSC particles could be controlled by the temperature and vapor pressure of both nitric acid and water in a non-linear way. Formation of polar stratospheric clouds may be forecasted on the basic of conditions of temperature and vapor contents of water and nitric acid.

  4. NARSTO EPA SS HOUSTON NH3 HNO3 DATA

    Atmospheric Science Data Center

    2014-04-25

    NARSTO EPA SS HOUSTON NH3 HNO3 DATA Project Title:  NARSTO Discipline:  ... Parameters:  Ammonia Nitric Acid Order Data:  ASDC Order Tool:   Order Data Guide Documents:  ... Earth Related Data:  Environmental Protection Agency Supersites Houston, Texas SCAR-B Block:  ...

  5. Measuring tropospheric HNO3 - Problems and prospects for Nylon filter and mist chamber techniques

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Vijgen, A. S.; Harriss, R. C.

    1990-01-01

    A series of laboratory and field measurements was performed to evaluate the mist chamber technique for determining tropospheric HNO3 concentrations. Both the mist chamber and standard Nylon filter techniques exhibit high collection efficiency and excellent agreement measuring HNO3 vapors from a permeation source. When simultaneously sampling ambient air in eastern Virginia, the Nylon filter measured an average of 70 percent higher HNO3 concentration than the mist chamber technique. The results indicate that O3 causes a low-level positive artifact interference in HNO3 measurements performed with the filter technique. This O3-induced error is small, however, compared to the large difference between atmospheric HNO3 concentrations determined with the two techniques. It is hypothesized that unidentified (organic?) nitrogen species in the atmosphere react for form NO3(-) on the filter and this phenomenon may interfere with Nylon filter measurements of HNO3 vapor. These potential interferences did not appear to affect measurements of HNO3 with the mist chamber method.

  6. Absorption of Near UV Light by HNO3/NO3(-) on Sapphire Surfaces.

    PubMed

    Sangwan, Manuvesh; Stockwell, William R; Stewart, Devoun; Zhu, Lei

    2016-05-12

    We have determined absorption of the near UV light (290-345 nm) by nitric acid (HNO3) deposition on sapphire window surfaces as a function of the HNO3 pressure, by using Brewster angle cavity ring-down spectroscopy. Apparent monolayer HNO3 surface absorption cross sections have been obtained; they range between (1.7 ± 1.1) × 10(-19) and (0.29 ± 0.03) × 10(-19) cm(2)/molecule. When nitric acid cross section values on sapphire surfaces were divided by those on fused silica surfaces for which only molecular HNO3 adsorption was reported, a new absorption band appeared in the 320-345 nm region. The shape of this absorption band is similar to that reported for surface nitrate (NO3(-)) at quartz/water interfaces, but is red-shifted by about 10 nm. Our study suggests that a small percentage (<7%) of adsorbed HNO3 formed by HNO3 deposition on sapphire surfaces is dissociated into surface nitrate on the time scale of about 5-7 min. Background transmission changes in the 320-350 nm region after exposing clean sapphire surfaces with many repeated HNO3 deposition/evacuation cycles are consistent with surface nitrate formation. We obtained nitrate surface absorption cross section data over 320-350 nm range. We also modeled photolysis rates of HNO3/NO3(-) on urban grimes. Atmospheric implications of the results are discussed.

  7. Vertical distribution of ozone and nitric acid vapor on the Mammoth Mountain, eastern Sierra Nevada, California.

    PubMed

    Bytnerowicz, Andrzej; Parker, David R; Padgett, Pamela E

    2002-01-01

    In August and September 1999 and 2000, concentrations of ozone (O3) and nitric acid vapor (HNO3) were monitored at an elevation gradient (2184-3325 m) on the Mammoth Mountain, eastern Sierra Nevada, California. Passive samplers were used for monitoring exposure to tropospheric O3 and HNO3 vapor. The 2-week average O3 concentrations ranged between 45 and 72 ppb, while HNO3 concentrations ranged between 0.06 and 0.52 microg/m3. Similar ranges of O3 and HNO3 were determined for 2 years of the study. No clear effects of elevation on concentrations of the two pollutants were detected. Concentrations of HNO3 were low and at the background levels expected for the eastern Sierra Nevada, while the measured concentrations of O3 were elevated. High concentrations of ozone in the study area were confirmed with an active UV absorption O3 monitor placed at the Mammoth Mountain Peak (September 5-14, 2000, average 24-h concentration of 56 ppb). PMID:12806035

  8. Physical Chemistry of the H2SO4/HNO3/H2O System: Implications for Polar Stratospheric Clouds.

    PubMed

    Molina, M J; Zhang, R; Wooldridge, P J; McMahon, J R; Kim, J E; Chang, H Y; Beyer, K D

    1993-09-10

    Polar stratospheric clouds (PSCs) play a key role in stratospheric ozone depletion. Surface-catalyzed reactions on PSC particles generate chlorine compounds that photolyze readily to yield chlorine radicals, which in turn destroy ozone very efficiently. The most prevalent PSCs form at temperatures several degrees above the ice frost point and are believed to consist of HNO(3) hydrates; however, their formation mechanism is unclear. Results of laboratory experiments are presented which indicate that the background stratospheric H(2)SO(4)/H(2)O aerosols provide an essential link in this mechanism: These liquid aerosols absorb significant amounts of HNO(3) vapor, leading most likely to the crystallization of nitric acid trihydrate (NAT). The frozen particles then grow to form PSCs by condensation of additional amounts of HNO(3) and H(2)O vapor. Furthermore, reaction probability measurements reveal that the chlorine radical precursors are formed readily at polar stratospheric temperatures not just on NAT and ice crystals, but also on liquid H(2)SO(4) solutions and on solid H(2)SO(4) hydrates. These results imply that the chlorine activation efficiency of the aerosol particles increases rapidly as the temperature approaches the ice frost point regardless of the phase or composition of the particles. PMID:17745351

  9. Physical Chemistry of the H2SO4/HNO3/H2O System: Implications for Polar Stratospheric Clouds.

    PubMed

    Molina, M J; Zhang, R; Wooldridge, P J; McMahon, J R; Kim, J E; Chang, H Y; Beyer, K D

    1993-09-10

    Polar stratospheric clouds (PSCs) play a key role in stratospheric ozone depletion. Surface-catalyzed reactions on PSC particles generate chlorine compounds that photolyze readily to yield chlorine radicals, which in turn destroy ozone very efficiently. The most prevalent PSCs form at temperatures several degrees above the ice frost point and are believed to consist of HNO(3) hydrates; however, their formation mechanism is unclear. Results of laboratory experiments are presented which indicate that the background stratospheric H(2)SO(4)/H(2)O aerosols provide an essential link in this mechanism: These liquid aerosols absorb significant amounts of HNO(3) vapor, leading most likely to the crystallization of nitric acid trihydrate (NAT). The frozen particles then grow to form PSCs by condensation of additional amounts of HNO(3) and H(2)O vapor. Furthermore, reaction probability measurements reveal that the chlorine radical precursors are formed readily at polar stratospheric temperatures not just on NAT and ice crystals, but also on liquid H(2)SO(4) solutions and on solid H(2)SO(4) hydrates. These results imply that the chlorine activation efficiency of the aerosol particles increases rapidly as the temperature approaches the ice frost point regardless of the phase or composition of the particles.

  10. Physical chemistry of the H2SO4/HNO3/H2O system - Implications for polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Molina, M. J.; Zhang, R.; Wooldridge, P. J.; Mcmahon, J. R.; Kim, J. E.; Chang, H. Y.; Beyer, K. D.

    1993-01-01

    Polar stratospheric clouds (PSCs) play a key role in stratospheric ozone depletion. Surface-catalyzed reactions on PSC particles generate chlorine compounds that photolyze readily to yield chlorine radicals, which in turn destroy ozone very efficiently. The most prevalent PSCs form at temperatures several degrees above the ice frost point and are believed to consist of HNO3 hydrates; however, their formation mechanism is unclear. Results of laboratory experiments are presented which indicate that the background stratospheric H2SO4/H2O aerosols provide an essential link in this mechanism: These liquid aerosols absorb significant amounts of HNO3 vapor, leading most likely to the crystallization of nitric acid trihydrate (NAT). The frozen particles then grow to form PSCs by condensation of additional amounts of HNO3 and H2O vapor. Furthermore, reaction probability measurements reveal that the chlorine radical precursors are formed readily at polar stratospheric temperatures not just on NAT and ice crystals, but also on liquid H2SO4 solutions and on solid H2SO4 hydrates. These results imply that the chlorine activation efficiency of the aerosol particles increases rapidly as the temperature approaches the ice frost point regardless of the phase or composition of the particles.

  11. Miniaturizing and automation of free acidity measurements for uranium (VI)-HNO3 solutions: Development of a new sequential injection analysis for a sustainable radio-analytical chemistry.

    PubMed

    Néri-Quiroz, José; Canto, Fabrice; Guillerme, Laurent; Couston, Laurent; Magnaldo, Alastair; Dugas, Vincent

    2016-10-01

    A miniaturized and automated approach for the determination of free acidity in solutions containing uranium (VI) is presented. The measurement technique is based on the concept of sequential injection analysis with on-line spectroscopic detection. The proposed methodology relies on the complexation and alkalimetric titration of nitric acid using a pH 5.6 sodium oxalate solution. The titration process is followed by UV/VIS detection at 650nm thanks to addition of Congo red as universal pH indicator. Mixing sequence as well as method validity was investigated by numerical simulation. This new analytical design allows fast (2.3min), reliable and accurate free acidity determination of low volume samples (10µL) containing uranium/[H(+)] moles ratio of 1:3 with relative standard deviation of <7.0% (n=11). The linearity range of the free nitric acid measurement is excellent up to 2.77molL(-1) with a correlation coefficient (R(2)) of 0.995. The method is specific, presence of actinide ions up to 0.54molL(-1) does not interfere on the determination of free nitric acid. In addition to automation, the developed sequential injection analysis method greatly improves the standard off-line oxalate complexation and alkalimetric titration method by reducing thousand fold the required sample volume, forty times the nuclear waste per analysis as well as the analysis time by eight fold. These analytical parameters are important especially in nuclear-related applications to improve laboratory safety, personnel exposure to radioactive samples and to drastically reduce environmental impacts or analytical radioactive waste. PMID:27474315

  12. Miniaturizing and automation of free acidity measurements for uranium (VI)-HNO3 solutions: Development of a new sequential injection analysis for a sustainable radio-analytical chemistry.

    PubMed

    Néri-Quiroz, José; Canto, Fabrice; Guillerme, Laurent; Couston, Laurent; Magnaldo, Alastair; Dugas, Vincent

    2016-10-01

    A miniaturized and automated approach for the determination of free acidity in solutions containing uranium (VI) is presented. The measurement technique is based on the concept of sequential injection analysis with on-line spectroscopic detection. The proposed methodology relies on the complexation and alkalimetric titration of nitric acid using a pH 5.6 sodium oxalate solution. The titration process is followed by UV/VIS detection at 650nm thanks to addition of Congo red as universal pH indicator. Mixing sequence as well as method validity was investigated by numerical simulation. This new analytical design allows fast (2.3min), reliable and accurate free acidity determination of low volume samples (10µL) containing uranium/[H(+)] moles ratio of 1:3 with relative standard deviation of <7.0% (n=11). The linearity range of the free nitric acid measurement is excellent up to 2.77molL(-1) with a correlation coefficient (R(2)) of 0.995. The method is specific, presence of actinide ions up to 0.54molL(-1) does not interfere on the determination of free nitric acid. In addition to automation, the developed sequential injection analysis method greatly improves the standard off-line oxalate complexation and alkalimetric titration method by reducing thousand fold the required sample volume, forty times the nuclear waste per analysis as well as the analysis time by eight fold. These analytical parameters are important especially in nuclear-related applications to improve laboratory safety, personnel exposure to radioactive samples and to drastically reduce environmental impacts or analytical radioactive waste.

  13. A Study on the Passivation Behavior and Semiconducting Properties of Gamma Titanium Aluminide in 0.1 N H2SO4, HNO3, and HClO4 Acidic Solutions

    NASA Astrophysics Data System (ADS)

    Memarbashi, S.; Saebnoori, E.; Shahrabi, T.

    2014-03-01

    The study focuses on the passivation behavior of single-gamma-phase titanium aluminide in acidic solutions with a particular emphasis on the role of oxidizing strength in characteristics of passive layer. The report includes potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies along with Mott-Schottky analysis in order to determine the corrosion behavior of the alloy and the semiconducting properties of the scale formed during exposure to acidic environment. Passive current density measured from potentiodynamic polarization curve, polarization resistance ( R p) estimated by EIS, defect density, and flatband potential drawn from Mott-Schottky analysis are mainly used in estimating the ability of passive film formed on alloy in protecting it against high corrosion rates in Sulfuric acid (a non-oxidizing acid), perchloric acid, and nitric acid (oxidizing acid with different oxidizing strength). The results show that passive current density ( i pass) in Sulfuric acid is 2.67 × 10-5 A cm-2, which is 2.5 and 3 times greater than the values obtained in perchloric acid ( i pass = 9.91 × 10-6) and nitric acid ( i pass = 7.98 × 10-6), respectively. EIS data reveal that the value of R p in sulfuric acid (20 kΩ cm2) is about three and five times smaller than that its value in perchloric acid and Nitric acid, respectively. Mott-Schottky analysis shows that the passive layer exhibits an n-type semiconducting characteristics irrespective of acidic environment. The greatest and the smallest values of donor density ( N D) are obtained for the passive scale formed in sulfuric acid ( N D, H2SO4 = 18.36 × 1019) and nitric acid ( N D, HNO3 = 13.13 × 1019), respectively. The report concludes that characteristics of the passive scale are directly affected by reduction potential of the acid, which is the criterion of its oxidizing strength. An increase in the oxidizing strength of the acidic solution results in formation of more protective and less

  14. Antarctic ozone - Meteoric control of HNO3

    NASA Astrophysics Data System (ADS)

    Prather, Michael J.; Rodriguez, Jose M.

    1988-01-01

    Atmospheric circulation leads to an accumulation of debris from meteors in the Antarctic stratosphere at the beginning of austral spring. The major component of meteoric material is alkaline, comprised predominantly of the oxides of magnesium and iron. These metals may neutralize the natural acidity of stratospheric aerosols, remove nitric acid from the gas phase, and bond it as metal nitrates in the aerosol phase. Removal of nitric acid vapor has been previously shown to be a critical link in the photochemical depletion of ozone in the Antarctic spring, by allowing for increased catalytic loss from chlorine and bromine.

  15. Impact of future land cover changes on HNO3 and O3 surface dry deposition

    NASA Astrophysics Data System (ADS)

    Verbeke, T.; Lathière, J.; Szopa, S.; de Noblet-Ducoudré, N.

    2015-07-01

    Dry deposition is a key component of surface-atmosphere exchange of compounds, acting as a sink for several chemical species. Meteorological factors, chemical properties of the trace gas considered and land surface properties are strong drivers of dry deposition efficiency and variability. Under both climatic and anthropogenic pressure, the vegetation distribution over the Earth has been changing a lot over the past centuries, and could be significantly altered in the future. In this study, we perform a modeling investigation of the potential impact of land-cover changes between present-day (2006) and the future (2050) on dry deposition rates, with special interest for ozone (O3) and nitric acid vapor (HNO3), two compounds which are characterized by very different physico-chemical properties. The 3-D chemistry transport model LMDz-INCA is used, considering changes in vegetation distribution based on the three future projections RCPs 2.6, 4.5 and 8.5. The 2050 RCP 8.5 vegetation distribution leads to a rise up to 7 % (+0.02 cm s-1) in VdO3 and a decrease of -0.06 cm s-1 in VdHNO3 relative to the present day values in tropical Africa, and up to +18 and -15 % respectively in Australia. When taking into account the RCP 4.5 scenario, which shows dramatic land cover change in Eurasia, VdHNO3 increases by up to 20 % (annual-mean value) and reduces VdO3 by the same magnitude in this region. When analyzing the impact of dry deposition change on atmospheric chemical composition, our model calculates that the effect is lower than 1 ppb on annual mean surface ozone concentration, for both for the RCP8.5 and RCP2.6 scenarios. The impact on HNO3 surface concentrations is more disparate between the two scenarios, regarding the spatial repartition of effects. In the case of the RCP 4.5 scenario, a significant increase of the surface O3 concentration reaching locally up to 5 ppb (+5 %) is calculated on average during the June-August period. This scenario induces also an increase of

  16. Strongly reduced Si surface recombination by charge injection during etching in diluted HF/HNO3.

    PubMed

    Greil, Stefanie M; Schöpke, Andreas; Rappich, Jörg

    2012-08-27

    Herein, we investigate the behaviour of the surface recombination of light-induced charge carriers during the etching of Si in alkaline (KOH) and acidic etching solutions of HF/HNO(3)/CH(3)COOH (HNA) or HF/HNO(3)/H(3)PO(4) (HNP) at different concentration ratios of HF and HNO(3) by means of photoluminescence (PL) measurements. The surface recombination velocity is strongly reduced during the first stages of etching in HF/HNO(3)-containing solutions pointing to a interface well passivated by the etching process, where a positive surface charge is induced by hole injection from NO-related surface species into the Si near-surface region (back surface field effect). This injected charge leads to a change in band bending by about 150 mV that repulses the light-induced charge carriers from the surface and therefore enhances the photoluminescence intensity, since non-radiative surface recombination is reduced.

  17. Effects of HNO3 concentration on the pit morphologies of aluminum foil etched in HNO3-HCl and HNO3-H2SO4-HCl solutions

    NASA Astrophysics Data System (ADS)

    Yi, Quan-xiu; He, Ye-dong; Peng, Ning; Song, Hong-zhou; Yang, Xiao-fei; Cai, Xiao-yu

    2016-01-01

    In this work, the effects of HNO3 concentration on the pit morphologies of high-cubic-texture aluminum foil etched in HNO3-HCl and HNO3-H2SO4-HCl solutions were investigated. When the aluminum foil was etched in HNO3-HCl solutions, the morphologies of pits transformed from irregular tunnels to typical tunnels (as inverted pyramids) and shallow cuboids as the HNO3 concentration in the etchant solution was increased. However, as the HCl concentration in the etchant solution was increased, the morphologies of pits transformed from shallow cuboids to typical tunnels (as inverted pyramids) and irregular tunnels. When the aluminum foil was etched in n N HNO3-(7.2- n) N H2SO4-0.8 N HCl solutions, the morphologies of the pits transformed from typical tunnels (i.e., the number of sub-tunnels formed on the main tunnels increased) to irregular tunnels (corrugated tunnels and polyline tunnels) as the HNO3 concentration in the etchant solution was increased. These effects are attributed primarily to corrosion on the (100) and (010) faces of pits being accelerated and to the (001) faces being prone to passivation to different degrees when various concentrations of HNO3 are added to the etchant solutions.

  18. Investigations on HONO formation from photolysis of adsorbed HNO3 on quartz glass surfaces.

    PubMed

    Laufs, Sebastian; Kleffmann, Jörg

    2016-04-14

    During the last few decades, nitrous acid (HONO) has attracted significant attention as a major source of the OH radical, the detergent of the atmosphere. However, the different daytime sources identified in the laboratory are still the subject of controversial discussion. In the present study, one of these postulated HONO sources, the heterogeneous photolysis of nitric acid (HNO3), was studied on quartz glass surfaces in a photo flow-reactor under atmospherically relevant conditions. In contrast to other investigations, a very low HNO3 photolysis frequency for HONO formation of J(HNO3→ HONO) = 2.4 × 10(-7) s(-1) (0° SZA, 50% r.h.) was determined. If these results can be translated to atmospheric surfaces, HNO3 photolysis cannot explain the significant HONO levels in the daytime atmosphere. In addition, it is demonstrated that even the small measured yields of HONO did not result from the direct photolysis of HNO3 but rather from the consecutive heterogeneous conversion of the primary photolysis product NO2 on the humid surfaces. The secondary NO2 conversion was not photo-enhanced on pure quartz glass surfaces in good agreement with former studies. A photolysis frequency for the primary reaction product NO2 of J(HNO3→ NO2) = 1.1 × 10(-6) s(-1) has been calculated (0° SZA, 50% r.h.), which indicates that renoxification by photolysis of adsorbed HNO3 on non-reactive surfaces is also a minor process in the atmosphere. PMID:26997156

  19. Interhemispheric Differences in Polar Stratospheric HNO3, H2O, CIO, and O3.

    PubMed

    Santee, M L; Read, W G; Waters, J W; Froidevaux, L; Manney, G L; Flower, D A; Jarnot, R F; Harwood, R S; Peckham, G E

    1995-02-10

    Simultaneous global measurements of nitric acid (HNO(3)), water (H(2)O), chlorine monoxide (CIO), and ozone (O(3)) in the stratosphere have been obtained over complete annual cycles in both hemispheres by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite. A sizeable decrease in gas-phase HNO(3) was evident in the lower stratospheric vortex over Antarctica by early June 1992, followed by a significant reduction in gas-phase H(2)O after mid-July. By mid-August, near the time of peak CIO, abundances of gas-phase HNO(3) and H(2)O were extremely low. The concentrations of HNO(3) and H(2)O over Antarctica remained depressed into November, well after temperatures in the lower stratosphere had risen above the evaporation threshold for polar stratospheric clouds, implying that denitrification and dehydration had occurred. No large decreases in either gas-phase HNO(3) or H(2)O were observed in the 1992-1993 Arctic winter vortex. Although CIO was enhanced over the Arctic as it was over the Antarctic, Arctic O(3) depletion was substantially smaller than that over Antarctica. A major factor currently limiting the formation of an Arctic ozone "hole" is the lack of denitrification in the northern polar vortex, but future cooling of the lower stratosphere could lead to more intense denitrification and consequently larger losses of Arctic ozone.

  20. Interhemispheric differences in polar stratospheric HNO3, H2O, ClO, and O3

    NASA Technical Reports Server (NTRS)

    Santee, M. L.; Read, W. G.; Waters, J. W.; Froidevaux, L.; Manney, G. L.; Flower, D. A.; Jarnot, R. F.; Harwood, R. S.; Peckham, G. E.

    1995-01-01

    Simultaneous global measurements of nitric acid (HNO3), water (H2O), chlorine monoxide (ClO), and ozone (O3) in the stratosphere have been obtained over complete annual cycles in both hemispheres by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite. A sizeable decrease in gas-phase HNO3 was evident in the lower stratospheric vortex over Antarctica by early June 1992, followed by a significant reduction in gas-phase H2O after mid-July. By mid-August, near the time of peak ClO, abundances of gas-phase HNO3 and H2O were extremely low. The concentrations of HNO3 and H2O over Antarctica remained depressed into November, well after temperatures in the lower stratosphere had risen above the evaporation threshold for polar stratospheric clouds, implying that denitrification and dehydration had occurred. No large decreases in either gas-phase HNO3 or H2O were observed in the 1992-1993 Arctic winter vortex. Although ClO was enhanced over the Arctic as it was over the Antarctic, Arctic O3 depletion was substantially smaller than that over Antarctica. A major factor currently limiting the formation of an Arctic ozone 'hole' is the lack of denitrification in the northern polar vortex, but future cooling of the lower stratosphere could lead to more intense denitrification and consequently larger losses of Arctic ozone.

  1. Condensation of HNO3 on falling ice particles - Mechanism for denitrification of the polar stratosphere

    NASA Technical Reports Server (NTRS)

    Wofsy, S. C.; Salawitch, R. J.; Yatteau, J. H.; Mcelroy, M. B.; Gandrud, B. W.

    1990-01-01

    Ice particles created in polar stratospheric cooling events are predicted to descend into Type I PSCs and accrete a coating of nitric acid trihydrate (NAT) that inhibits evaporation. Coated particles efficiently strip HNO3 from the atmosphere, providing a mechanism for denitrification without significant dehydration. Coatings that disintegrate may release large particles of NAT that influence subsequent particle growth.

  2. Rate of reaction of OH with HNO3

    NASA Technical Reports Server (NTRS)

    Wine, P. H.; Ravishankara, A. R.; Kreutter, N. M.; Shah, R. C.; Nicovich, J. M.; Thompson, R. L.; Wuebbles, D. J.

    1981-01-01

    Measurements of the kinetics of the reaction of OH with HNO3, and mechanisms of HNO3 removal from the stratosphere, are reported. Bimolecular rate constants were determined at temperatures between 224 and 366 K by monitoring the concentrations of OH radicals produced by HNO3 photolysis and HNO3 according to their resonance fluorescence and 184.9-nm absorption, respectively. The rate constant measured at 298 K is found to be somewhat faster than previously accepted values, with a negative temperature dependence. Calculations of a one-dimensional transport-kinetic atmospheric model on the basis of the new rate constant indicate reductions in O3 depletion due to chlorofluoromethane release and NOx injection, of magnitudes dependent on the nature of the reaction products.

  3. Variable temperature pressure broadening of HNO3 in the millimeter wave spectral region

    NASA Technical Reports Server (NTRS)

    Goyette, Thomas M.; Guo, Wei; Delucia, Frank C.; Helminger, Paul

    1991-01-01

    Measurements were performed for both O2 and N2 broadening in the 100-380 K temperature range by using a heated equilibrium cell for elevated temperatures and the utilization of a collisionally cooled cell at the lower temperatures where HNO3 has a small vapor pressure. Observed pressure-broadening data can be fit to the normal empirical law, giving n values between 0.62 and 0.84.

  4. Persistent Water-Nitric Acid Condensate with Saturation Water Vapor Pressure Greater than That of Hexagonal Ice.

    PubMed

    Gao, Ru-Shan; Gierczak, Tomasz; Thornberry, Troy D; Rollins, Andrew W; Burkholder, James B; Telg, Hagen; Voigt, Christiane; Peter, Thomas; Fahey, David W

    2016-03-10

    A laboratory chilled mirror hygrometer (CMH), exposed to an airstream containing water vapor (H2O) and nitric acid (HNO3), has been used to demonstrate the existence of a persistent water-nitric acid condensate that has a saturation H2O vapor pressure greater than that of hexagonal ice (Ih). The condensate was routinely formed on the mirror by removing HNO3 from the airstream following the formation of an initial condensate on the mirror that resembled nitric acid trihydrate (NAT). Typical conditions for the formation of the persistent condensate were a H2O mixing ratio greater than 18 ppm, pressure of 128 hPa, and mirror temperature between 202 and 216 K. In steady-state operation, a CMH maintains a condensate of constant optical diffusivity on a mirror through control of only the mirror temperature. Maintaining the persistent condensate on the mirror required that the mirror temperature be below the H2O saturation temperature with respect to Ih by as much as 3 K, corresponding to up to 63% H2O supersaturation with respect to Ih. The condensate was observed to persist in steady state for up to 16 h. Compositional analysis of the condensate confirmed the co-condensation of H2O and HNO3 and thereby strongly supports the conclusion that the Ih supersaturation is due to residual HNO3 in the condensate. Although the exact structure or stoichiometry of the condensate could not be determined, other known stable phases of HNO3 and H2O are excluded as possible condensates. This persistent condensate, if it also forms in the upper tropical troposphere, might explain some of the high Ih supersaturations in cirrus and contrails that have been reported in the tropical tropopause region. PMID:26447682

  5. Persistent Water-Nitric Acid Condensate with Saturation Water Vapor Pressure Greater than That of Hexagonal Ice.

    PubMed

    Gao, Ru-Shan; Gierczak, Tomasz; Thornberry, Troy D; Rollins, Andrew W; Burkholder, James B; Telg, Hagen; Voigt, Christiane; Peter, Thomas; Fahey, David W

    2016-03-10

    A laboratory chilled mirror hygrometer (CMH), exposed to an airstream containing water vapor (H2O) and nitric acid (HNO3), has been used to demonstrate the existence of a persistent water-nitric acid condensate that has a saturation H2O vapor pressure greater than that of hexagonal ice (Ih). The condensate was routinely formed on the mirror by removing HNO3 from the airstream following the formation of an initial condensate on the mirror that resembled nitric acid trihydrate (NAT). Typical conditions for the formation of the persistent condensate were a H2O mixing ratio greater than 18 ppm, pressure of 128 hPa, and mirror temperature between 202 and 216 K. In steady-state operation, a CMH maintains a condensate of constant optical diffusivity on a mirror through control of only the mirror temperature. Maintaining the persistent condensate on the mirror required that the mirror temperature be below the H2O saturation temperature with respect to Ih by as much as 3 K, corresponding to up to 63% H2O supersaturation with respect to Ih. The condensate was observed to persist in steady state for up to 16 h. Compositional analysis of the condensate confirmed the co-condensation of H2O and HNO3 and thereby strongly supports the conclusion that the Ih supersaturation is due to residual HNO3 in the condensate. Although the exact structure or stoichiometry of the condensate could not be determined, other known stable phases of HNO3 and H2O are excluded as possible condensates. This persistent condensate, if it also forms in the upper tropical troposphere, might explain some of the high Ih supersaturations in cirrus and contrails that have been reported in the tropical tropopause region.

  6. The vapor pressures of supercooled NHO3/H2O solutions. [in polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Hanson, David R.

    1990-01-01

    A procedure utilizing the Gibbs-Duhem relation is used to extrapolate vapor pressures of supercooled HNO3 mixtures to 190 K. Values of A and B from the equation logP = A - B/T are presented for solutions between 0.20 and 0.25 mole fraction HNO3. In the stratosphere, if sufficient HNO3 vapor is present because it has not come into equilibrium with the nitric acid trihydrate, supercooled nitric acid solutions could condense at temperatures up to 1.5 + or - 0.8 K above the ice point.

  7. Growth of upper tropospheric aerosols due to uptake of HNO3

    NASA Astrophysics Data System (ADS)

    Romakkaniemi, S.; Kokkola, H.; Petzold, A.; Laaksonen, A.

    2004-01-01

    The effect of nitric acid on the equilibrium size distributions of upper tropospheric aerosols is calculated as a function of relative humidity. It is shown that HNO3 concentrations above a few tenths of a ppb can cause substantial increases in haze mode particle concentrations at relative humidities at about 60% and above. The effect can be strongly magnified when letovicite particles are present in addition to sulfuric acid aerosols. This is mainly due to the lowering of the deliquescence RH of letovicite in the presence of gaseous nitric acid at low temperatures. We have also compared equilibrium calculations of the HNO3 effect with observations of increased haze mode concentrations at relative humidities above 50% (Petzold et al., 2000). Nitric acid mixing ratios on the order of 0.5-2 ppb may explain the observed increase of haze mode particles at least partially.

  8. First characterization and validation of FORLI-HNO3 vertical profiles retrieved from IASI/Metop

    NASA Astrophysics Data System (ADS)

    Ronsmans, Gaétane; Langerock, Bavo; Wespes, Catherine; Hannigan, James W.; Hase, Frank; Kerzenmacher, Tobias; Mahieu, Emmanuel; Schneider, Matthias; Smale, Dan; Hurtmans, Daniel; De Mazière, Martine; Clerbaux, Cathy; Coheur, Pierre-François

    2016-09-01

    Knowing the spatial and seasonal distributions of nitric acid (HNO3) around the globe is of great interest and allows us to comprehend the processes regulating stratospheric ozone, especially in the polar regions. Due to its unprecedented spatial and temporal sampling, the nadir-viewing Infrared Atmospheric Sounding Interferometer (IASI) is capable of sounding the atmosphere twice a day globally, with good spectral resolution and low noise. With the Fast Optimal Retrievals on Layers for IASI (FORLI) algorithm, we are retrieving, in near real time, columns as well as vertical profiles of several atmospheric species, among which is HNO3. We present in this paper the first characterization of the FORLI-HNO3 profile products, in terms of vertical sensitivity and error budgets. We show that the sensitivity of IASI to HNO3 is highest in the lower stratosphere (10-20 km), where the largest amounts of HNO3 are found, but that the vertical sensitivity of IASI only allows one level of information on the profile (degrees of freedom for signal, DOFS; ˜ 1). The sensitivity near the surface is negligible in most cases, and for this reason, a partial column (5-35 km) is used for the analyses. Both vertical profiles and partial columns are compared to FTIR ground-based measurements from the Network for the Detection of Atmospheric Composition Change (NDACC) to characterize the accuracy and precision of the FORLI-HNO3 product. The profile validation is conducted through the smoothing of the raw FTIR profiles by the IASI averaging kernels and gives good results, with a slight overestimation of IASI measurements in the upper troposphere/lower stratosphere (UTLS) at the six chosen stations (Thule, Kiruna, Jungfraujoch, Izaña, Lauder and Arrival Heights). The validation of the partial columns (5-35 km) is also conclusive with a mean correlation of 0.93 between IASI and the FTIR measurements. An initial survey of the HNO3 spatial and seasonal variabilities obtained from IASI

  9. HNO3 profiles obtained during the EASOE campaign

    NASA Technical Reports Server (NTRS)

    Murcray, F. J.; Starkey, J. R.; Williams, W. J.; Matthews, W. A.; Schmidt, U.; Aimedieu, P.; Camy-Peyret, C.

    1994-01-01

    A small cryogenically cooled spectrometer system designed to obtain atmospheric emission spectra in the 7.5 micrometer to 13.0 micrometer region was flown piggyback on 9 balloon flights from ESRANGE (67.9 deg N, 21.2 deg E) during the European Arctic Stratospheric Ozone Experiment (EASOE) campaign. Initial analysis of the spectra obtained has been concentrated on obtaining HNO3 profiles for the various flights. HNO3 profiles for 17 December 1991, 9 January 1992, 22 January 1992, 5 February 1992 and 14 March 1992 are presented.

  10. Infrared spectra of solid films formed from vapors containing water and nitric acid

    NASA Technical Reports Server (NTRS)

    Smith, Roland H.; Leu, Ming-Taun; Keyser, Leon F.

    1991-01-01

    The paper presents infrared spectra recorded at 188 K for crystalline mono- and trihydrates of nitric acid formed by vapor deposition, along with spectra of fully deuterated forms of these compounds. The spectra are interpreted in terms of the known ionic structures of the hydrates and the known spectra of oxonium and nitrate ions. Two additional species were identified: a molecular hydrogen-bonded HNO3-H2O complex, stable only at temperatures below 120 or 150 K, and a substance considered to be a crystalline mixtgure of trihydrate and ice. The relevance of these findings to the stratospheric ozone hole problem is discussed.

  11. HO2NO2 and HNO3 in the coastal Antarctic winter night: A "lab-in-the-field" experiment

    NASA Astrophysics Data System (ADS)

    Jones, Anna; Brough, Neil; Anderson, Philip; Wolff, Eric

    2015-04-01

    Observations of peroxynitric acid (HO2NO2) and nitric acid (HNO3) were made during a 4 month period of Antarctic winter darkness at the coastal Antarctic research station, Halley. Mixing ratios of HNO3 ranged from instrumental detection limits to 8 parts per trillion by volume (pptv), and of HO2NO2 from detection limits to 5 pptv; the average ratio of HNO3:HO2NO2 was 2.0(±0.6):1, with HNO3 always present at greater mixing ratios than HO2NO2 during the winter darkness. An extremely strong association existed for the entire measurement period between mixing ratios of the respective trace gases and temperature: for HO2NO2, R2 = 0.72, and for HNO3, R2 = 0.70. We focus on three cases with considerable variation in temperature, where wind speeds were low and constant, such that, with the lack of photochemistry, changes in mixing ratio were likely to be driven by physical mechanisms alone. We derived enthalpies of adsorption (ΔHads) for these three cases. The average ΔHads for HNO3 was -42±2 kJ.mol-1 and for HO2NO2 was -56±1kJ.mol-1; these values are extremely close to those derived in laboratory studies. This exercise demonstrates i) that adsorption to/desorption from the snow pack should be taken into account when addressing budgets of boundary layer HO2NO2 and HNO3 at any snow-covered site, and ii) that Antarctic winter can be used as a natural 'laboratory in the field' for testing data on physical exchange mechanisms.

  12. Morphological modification of MWCNT functionalized with HNO3/H2SO4 mixtures.

    PubMed

    Pistone, A; Ferlazzo, A; Lanza, M; Milone, C; Iannazzo, D; Piperno, A; Piperopoulos, E; Galvagno, S

    2012-06-01

    The acidic oxidation with HNO3/H2SO4 mixtures is widely reported as an effective method to functionalize multi-walled carbon nanotubes (MWCNT). Although effective, a bad control of the oxidation conditions frequently cause serious modifications of carbon nanotube network, limiting further potential applications. Investigations about the effect of functionalization operating conditions on the morphological, chemical and chemical-physical properties of MWCNT can be useful for a proper setting of oxidation reactions of MWCNT according to their specific applications. In this work the effect of HNO3/H2SO4 ratio on the morphological and chemical-physical properties and on the degree of functionalization of MWCNT was investigated. Electron microscopy, thermogravimetric, X-ray diffraction, titration and water dispersion analyses clearly revealed that the increase of the amount of concentrated sulphuric acid in the HNO3/H2SO4 mixture lead to an increase of the amount of functional groups on the MWCNT surface but also to an increase of structural damage in terms of tube cutting and generation of additional defects in the graphitic network of pristine PMID:22905576

  13. Growth of upper tropospheric aerosols due to uptake of HNO3

    NASA Astrophysics Data System (ADS)

    Romakkaniemi, S.; Kokkola, H.; Petzold, A.; Laaksonen, A.

    2004-03-01

    The effect of nitric acid on the equilibrium size distributions of upper tropospheric aerosols is calculated as a function of relative humidity. It is shown that HNO3 concentrations above a few tenths of a ppb can cause substantial increases in haze mode particle concentrations at relative humidities at about 60% and above. The effect can be strongly magnified when letovicite particles are present in addition to sulfuric acid aerosols. Letovicite particles are less acidic than the sulfuric acid particles and so more nitric acid can be absorbed. This effect can be seen even at RH below 50% due to the lowering of the deliquescence RH of letovicite in the presence of gaseous nitric acid at low temperatures. We have also compared equilibrium calculations of the HNO3 effect with observations of increased haze mode concentrations at relative humidities above 50% (Petzold et al., 2000). Nitric acid mixing ratios on the order of 0.5-2ppb may explain the observed increase of haze mode particles at least partially.

  14. Participation of HNO3 CIMS Instrument in the Sage III Ozone Loss and Validation Experiment (SOLVE)

    NASA Technical Reports Server (NTRS)

    Eisele, F. L.

    2001-01-01

    This project was part of a larger SOLVE project led by Paul Wennberg at California Institute of Technology. The work completed on this project included participating in the installation and preflight testing of a new chemical ionization mass spectrometer for measuring gas and particle phase nitric acid on the ER-2. The investigators subsequently participated in SOLVE where additional instrument improvements were made and a substantial data set was generated. The two Georgia Tech investigators that participated in this work (Fred Eisele and Dave Tanner) had previously been responsible for much of the design and construction of the ion source and mass spectrometer which would be used to measure HNO3 in SOLVE, with Caltech focusing on inlets, calibration, gas supplies/pumping computer control, and overall integration. Thus, a similar focus remained during the SOLVE measurements though all investigators worked on most if not all aspects of the instrument at some point in the mission. Some of the more interesting results from the study included measurements of nitric acid on what are thought to be 5-20 microns diameter individual particles which could supply a local mechanism for HNO3 removal, Nitric acid measurements on SOLVE were completed as a collaborative effort with a great deal of overlap between this project and the larger parent project led by Paul Wennberg. As such, the instrumentation used, its operation, and the resulting measurements are far more fully discussed in the attached report (appendix A) which describes the joint SOLVE nitric acid measurement effort.

  15. Impact of future land-cover changes on HNO3 and O3 surface dry deposition

    NASA Astrophysics Data System (ADS)

    Verbeke, T.; Lathière, J.; Szopa, S.; de Noblet-Ducoudré, N.

    2015-12-01

    Dry deposition is a key component of surface-atmosphere exchange of compounds, acting as a sink for several chemical species. Meteorological factors, chemical properties of the trace gas considered and land surface properties are strong drivers of dry deposition efficiency and variability. Under both climatic and anthropogenic pressure, the vegetation distribution over the Earth has been changing a lot over the past centuries and could be significantly altered in the future. In this study, we perform a modeling investigation of the potential impact of land-cover changes between the present day (2006) and the future (2050) on dry deposition velocities at the surface, with special interest for ozone (O3) and nitric acid (HNO3), two compounds which are characterized by very different physicochemical properties. The 3-D chemistry-transport model LMDz-INCA is used, considering changes in vegetation distribution based on the three future projections, RCPs 2.6, 4.5 and 8.5, and present-day (2007) meteorology. The 2050 RCP 8.5 vegetation distribution leads to a rise of up to 7 % (+0.02 cm s-1) in the surface deposition velocity calculated for ozone (Vd,O3) and a decrease of -0.06 cm s-1 in the surface deposition velocity calculated for nitric acid (Vd,HNO3) relative to the present-day values in tropical Africa and up to +18 and -15 %, respectively, in Australia. When taking into account the RCP 4.5 scenario, which shows dramatic land-cover change in Eurasia, Vd,HNO3 increases by up to 20 % (annual-mean value) and reduces Vd,O3 by the same magnitude in this region. When analyzing the impact of surface dry deposition change on atmospheric chemical composition, our model calculates that the effect is lower than 1 ppb on annual-mean surface ozone concentration for both the RCP 8.5 and RCP 2.6 scenarios. The impact on HNO3 surface concentrations is more disparate between the two scenarios regarding the spatial repartition of effects. In the case of the RCP 4.5 scenario, a

  16. Measurements of HCl and HNO3 with the new research aircraft HALO - Quantification of the stratospheric contribution to the O3 and HNO3 budget in the UT/LS

    NASA Astrophysics Data System (ADS)

    Jurkat, Tina; Kaufmann, Stefan; Voigt, Christiane; Zahn, Andreas; Schlager, Hans; Engel, Andreas; Bönisch, Harald; Dörnbrack, Andreas

    2013-04-01

    Dynamic and chemical processes modify the ozone (O3) budget of the upper troposphere/lower stratosphere, leading to locally variable O3 trends. In this region, O3 acts as a strong greenhouse gas with a net positive radiative forcing. It has been suggested, that the correlation of the stratospheric tracer hydrochloric acid (HCl) with O3 can be used to quantify stratospheric O3 in the UT/LS region (Marcy et al., 2004). The question is, whether the stratospheric contribution to the nitric acid (HNO3) budget in the UT/LS can be determined by a similar approach in order to differentiate between tropospheric and stratospheric sources of HNO3. To this end, we performed in situ measurements of HCl and HNO3 with a newly developed Atmospheric chemical Ionization Mass Spectrometer (AIMS) during the TACTS (Transport and Composition in the UTLS) / ESMVal (Earth System Model Validation) mission in August/September 2012. The linear quadrupole mass spectrometer deployed aboard the new German research aircraft HALO was equipped with a new discharge source generating SF5- reagent ions and an in-flight calibration allowing for accurate, spatially highly resolved trace gas measurements. In addition, sulfur dioxide (SO2), nitrous acid (HONO) and chlorine nitrate (ClONO2) have been simultaneously detected with the AIMS instrument. Here, we show trace gas distributions of HCl and HNO3 measured during a North-South transect from Northern Europe to Antarctica (68° N to 65° S) at 8 to 15 km altitude and discuss their latitude dependence. In particular, we investigate the stratospheric ozone contribution to the ozone budget in the mid-latitude UT/LS using correlations of HCl with O3. Differences in these correlations in the subtropical and Polar regions are discussed. A similar approach is used to quantify the HNO3 budget of the UT/LS. We identify unpolluted atmospheric background distributions and various tropospheric HNO3 sources in specific regions. Our observations can be compared to

  17. The NO(x)-HNO3 System in the Lower Stratosphere: Insights from In Situ Measurements and Implications of the J(HNO3)-[OH] Relationship

    NASA Technical Reports Server (NTRS)

    Perkins, K. K.; Hanisco, T. F.; Cohen, R. C.; Koch, L. C.; Stimpfle, R. M.; Voss, P. B.; Bonne, G. P.; Lanzendorf, E. J.; Anderson, J. G.; Wennberg, P. O.

    2001-01-01

    During the 1997 Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) mission, simultaneous in situ observations of NOx and HOx radicals, their precursors, and the radiation field were obtained in the lower stratosphere. We use these observations to evaluate the primary mechanisms that control NOx-HNO3 exchange and to understand their control over the partitioning between NO2 and HNO3 in regions of continuous sunlight. We calculate NOx production (PNOx) and loss (LNOx) in a manner directly constrained by the in situ measurements and current rate constant recommendations, using approaches for representing albedo, overhead O3 and [OH] that reduce model uncertainty. We find a consistent discrepancy of 18% between modeled rates of NOx production and loss (LNOx = 1.18P(sub NOx)), which is within the measurement uncertainty of +/- 27%. The partitioning between NOx production processes is [HNO3 + OH (41 +/- 2)%; HNO3 + hv (59 +/- 2)%] and between NOx loss processes is [NO2 + OH, 90% to >97%; BrONO2 + H2O, 10% to <3%]. The steady-state description of NOx-HNO3 exchange reveals the significant influence of the tight correlation between the photolysis rate of HNO3 and [OH] established by in situ measurements throughout the lower stratosphere. Parametrizing this relationship, we find: (1) the steady-state value of [NO2](sub 24h-avg)/[HNO3] in the continuously sunlit, lower stratosphere is a function only of temperature and number density; and (2) the partitioning of NOx production between HNO3 + OH and HNO3 + hv is nearly constant throughout most of the lower stratosphere. We describe a methodology (functions of latitude, day, temperature, and pressure) for accurately predicting the steady-state value of [NO2](sub 24h-avg)/[HNO3] and the partitioning of NOx production within these regions. The results establish a metric to compare observations of [NO2](sub 24h-avg)/[HNO3] within the continuously sunlit region and provide a simple diagnostic for evaluating the

  18. Measurement of OH, H2SO4, MSA, and HNO3 Aboard the P-3B Aircraft

    NASA Technical Reports Server (NTRS)

    Eisele, F. L.

    2003-01-01

    This paper addresses the measurement of OH, H2SO4, MSA, and HNO3 aboard the P-3B aircraft under the following headings: 1) Performance Report; 2) Highlights of OH, H2SO4, and MSA Measurements Made Aboard the NASA P-3B During TRACE-P; 3) Development and characteristics of an airborne-based instrument used to measure nitric acid during the NASA TRACE-P field experiment.

  19. Microphysical properties of synoptic scale polar stratospheric clouds: in situ measurements of unexpectedly large HNO3 containing particles in the Arctic vortex

    NASA Astrophysics Data System (ADS)

    Molleker, S.; Borrmann, S.; Schlager, H.; Luo, B.; Frey, W.; Klingebiel, M.; Weigel, R.; Ebert, M.; Mitev, V.; Matthey, R.; Woiwode, W.; Oelhaf, H.; Dörnbrack, A.; Stratmann, G.; Grooß, J.-U.; Günther, G.; Vogel, B.; Müller, R.; Krämer, M.; Meyer, J.; Cairo, F.

    2014-05-01

    In January 2010 and December 2011 synoptic scale PSC fields were probed during seven flights of the high altitude research aircraft M-55 Geophysica within the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interaction.) and the ESSenCe (ESSenCe: ESA Sounder Campaign) projects. Particle size distributions in a diameter range between 0.46 μm and 40 μm were recorded simultaneously by up to four different optical in situ instruments. Three of these particle instruments are based on the detection of forward scattered light by single particles. The fourth instrument is a grey scale optical array imaging probe. Optical particle diameters of up to 35 μm were detected with particle number densities and total particle volumes exceeding previous Arctic measurements. Also, gas phase and particle bound NOy were measured, as well as water vapor concentrations, and other variables. Two remote sensing particle instruments, the Miniature Aerosol Lidar (MAL) and the backscatter sonde (MAS, Multiwavelenght Aerosol Scatterometer) showed the synoptic scale of the encountered PSCs. The particle mode below 2 μm in size diameter has been identified as supercooled ternary solution droplets (STS). The PSC particles in the size range above 2 μm in diameter are considered to consist of nitric acid hydrates or ice, and the particles' high HNO3 content was confirmed by the NOy instrument. Assuming a particle composition of nitric acid trihydrate (NAT), the optically measured size distributions result in particle-phase HNO3 mixing ratios exceeding available stratospheric values. In particular, with respect to the denitrification by sedimentation of large HNO3-contaning particles, generally considered as NAT, our new measurements raise questions concerning composition, shape and nucleation pathways. Measurement uncertainties are discussed concerning probable overestimations of measured particle sizes

  20. Microphysical properties of synoptic-scale polar stratospheric clouds: in situ measurements of unexpectedly large HNO3-containing particles in the Arctic vortex

    NASA Astrophysics Data System (ADS)

    Molleker, S.; Borrmann, S.; Schlager, H.; Luo, B.; Frey, W.; Klingebiel, M.; Weigel, R.; Ebert, M.; Mitev, V.; Matthey, R.; Woiwode, W.; Oelhaf, H.; Dörnbrack, A.; Stratmann, G.; Grooß, J.-U.; Günther, G.; Vogel, B.; Müller, R.; Krämer, M.; Meyer, J.; Cairo, F.

    2014-10-01

    In January 2010 and December 2011, synoptic-scale polar stratospheric cloud (PSC) fields were probed during seven flights of the high-altitude research aircraft M-55 Geophysica within the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interaction) and the ESSenCe (ESSenCe: ESA Sounder Campaign) projects. Particle size distributions in a diameter range between 0.46 and 40μm were recorded by four different optical in situ instruments. Three of these particle instruments are based on the detection of forward-scattered light by single particles. The fourth instrument is a grayscale optical array imaging probe. Optical particle diameters of up to 35μm were detected with particle number densities and total particle volumes exceeding previous Arctic measurements. Also, gas-phase and particle-bound NOy was measured, as well as water vapor concentrations. The optical characteristics of the clouds were measured by the remote sensing lidar MAL (Miniature Aerosol Lidar) and by the in situ backscatter sonde MAS (Multiwavelength Aerosol Scatterometer), showing the synoptic scale of the encountered PSCs. The particle mode below 2μm in size diameter has been identified as supercooled ternary solution (STS) droplets. The PSC particles in the size range above 2μm in diameter are considered to consist of nitric acid hydrates, and the particles' high HNO3 content was confirmed by the NOy instrument. Assuming a particle composition of nitric acid trihydrate (NAT), the optically measured size distributions result in particle-phase HNO3 mixing ratios exceeding available stratospheric values. Therefore the measurement uncertainties concerning probable overestimations of measured particle sizes and volumes are discussed in detail. We hypothesize that either a strong asphericity or an alternate particle composition (e.g., water ice coated with NAT) could explain our observations. In particular

  1. Aircraft measurements of O3, HNO3, and N2O in the winter Arctic lower stratosphere during the Stratosphere-Troposphere Experiment by Aircraft Measurements (STREAM) 1

    NASA Astrophysics Data System (ADS)

    Bregman, A.; van Velthoven, P. F. J.; Wienhold, F. G.; Fischer, H.; Zenker, T.; Waibel, A.; Frenzel, A.; Arnold, F.; Harris, G. W.; Bolder, M. J. A.; Lelieveld, J.

    1995-06-01

    Simultaneous in situ measurements of O3, HNO3, and N2O were performed in the Arctic (68°-74°N) lower stratosphere during February 1993 on board a Cessna Citation aircraft up to 12.5 km altitude, during the first Stratosphere-Troposphere Experiment by Aircraft Measurements (STREAM) campaign. Strong variations in the concentrations, distributions, and ratios of these trace gases were found from the maximum altitude down to the tropopause. Close to the tropopause, vortex air was present with relatively low N2O concentrations. The observed N2O-HNO3 relation agrees with earlier measurements of total nitrogen and N2O inside the vortex, suggesting subsidence of vortex air across the bottom of the vortex. This air also contained low O3 concentrations relative to N2O, indicating enhanced O3 loss by chemical reactions involving stratospheric particles. Based on trajectory calculations and assuming a potential temperature cooling rate of 0.6 K d-1, we estimate an O3 loss of 4-7 ppbv d-1 (0.9-1.2% d-1), in the Arctic lower stratosphere for the period January-February 1993. Air parcels originating from middle latitudes, containing relatively low O3 and N2O concentrations, may have originated from the vortex earlier in the winter. In addition, the results also show high HNO3 concentrations relative to O3 and N2O. Air parcels originating from high latitudes may have been enriched in HNO3 by sedimentation and evaporation of nitric acid containing particles, which would explain the relatively high HNO3 concentrations and HNO3/O3 ratios measured. Heterogeneous chemistry on sulfuric acid particles, probably enhanced in concentration by gravitational settling of the Pinatubo aerosol, is the most plausible explanation for the observed high HNO3 concentrations relative to N2O in air parcels originating from midlatitudes.

  2. HNO3 From MLS: Building on the UARS Legacy With Aura Measurements

    NASA Astrophysics Data System (ADS)

    Santee, M. L.; Manney, G. L.; Read, W. G.; Livesey, N. J.; Filipiak, M. J.; Waters, J. W.

    2003-12-01

    The Microwave Limb Sounder (MLS) onboard the Upper Atmosphere Research Satellite (UARS) measured the global distribution of stratospheric HNO3 over annual cycles for much of the 1990s, albeit with reduced sampling frequency in the latter half of the decade. The UARS MLS HNO3 dataset, unique in its scope, has previously been studied to explore the seasonal, interhemispheric, and interannual variations in the distribution of HNO3. This work, however, suffered from a number of limitations: It was confined to a single level in the lower stratosphere (465 K potential temperature), it was based on version~4 MLS data, and it relied heavily on zonal-mean comparisons of the evolution of HNO3 in the northern and southern hemispheres. Here we update and significantly expand the previous work by examining the distribution of HNO3 throughout the lower and middle stratosphere from 420 to 960 K. We use version~6 MLS HNO3 data, which, in addition to having much better precision, a larger vertical range, and better definition of the HNO3 profile, have also been corrected to account for the neglect of some excited vibrational state lines that caused the version~4 (and version~5) retrievals to substantially overestimate HNO3 peak values. In addition, we calculate averages over equivalent latitude, which are more representative of vortex behavior than zonal means, especially in the Arctic. This work provides a comprehensive picture of the behavior of stratospheric HNO3 during the UARS timeframe and establishes an important baseline for upcoming measurements from the EOS Aura mission, which will include a second-generation MLS experiment. The capability of EOS MLS is greatly enhanced over that of UARS MLS. We review the anticipated improvements in the EOS MLS HNO3 measurements (e.g., better spatial and temporal coverage, better horizontal and vertical resolution, larger vertical range), show some results from retrieval simulations, and discuss a few specific polar process studies that

  3. Fluxless soldering using activated acid vapors

    SciTech Connect

    Frear, D.R.; Keicher, D.M.

    1992-01-01

    Acid vapors have been used to fluxlessly reduce metal oxides and enhance wetting of solder on metallizations. Dilute solutions of hydrogen, acetic acid and formic acid in an inert carrier gas of nitrogen or argon were used with the sessile drop technique for 60Sn-40 Pb solder on Cu and Au/Ni metallizations. The time to reduce metal oxides and the extent of wetting as a function of acid vapor concentrations were characterized. Acetic and formic acids reduce the surface metal oxides sufficiently to form metallurgically sound solder joints. Hydrogen did not reduce oxides rapidly enough at 220{degree}C to be suitable for soldering applications. The optimum conditions for oxide reduction with formic acid was with an acid vapor concentration in nitrogen carrier gas of 4% for Cu metallizations and 1.6% on Au/Ni. The acetic acid vapor concentration, also in nitrogen, was optimized at 1.5% for both metallizations. Above a vapor concentration of 1.5%, the acetic acid combined with the bare metal to form acetates which increased the wetting time. These results indicate that acid vapor fluxless soldering is a viable alternative to traditional flux soldering.

  4. Interaction of acetone, hydroxyacetone, acetaldehyde and benzaldehyde with the surface of water ice and HNO3·3H2O ice.

    PubMed

    Lasne, Jérôme; Laffon, Carine; Parent, Philippe

    2012-01-14

    Oxygenated volatile organic compounds (OVOCs) influence the oxidative properties of the atmosphere, and their transport from the ground may occur by scavenging by the HNO(3)-rich supercooled water droplets found in polluted convective air masses. With infrared spectroscopy, we have studied the interactions of four typical atmospheric OVOCs (acetone, hydroxyacetone, acetaldehyde and benzaldehyde) with model surfaces of water ice and of trihydrated nitric acid (NAT) ice. We show that these molecules weakly adsorb on water ice and NAT by hydrogen bonding. No chemical reaction occurs between the molecules and the NAT substrate, the OVOCs remaining intact when in contact with hydrated HNO(3) in atmospheric ice clouds.

  5. FTIR Spectroscopy of HNO3 and NO2 Relevant to Stratospheric Wake Analysis

    NASA Technical Reports Server (NTRS)

    Abina, Rafiu A.; Misra, Prabhakar; Okabe, Hideo; Chu, P. M.; Sams, Robert L.

    1997-01-01

    The Fourier Transform Infrared (FTIR) technique has been employed to measure absolute concentrations of nitric acid (HNO3) and nitrogen dioxide (NO2) with 1/cm resolution and an absorption pathlength of 4 m under quasi-static and flow conditions at atmospheric pressure and room temperature. Water features seen under quasi-static conditions diminished in intensity under flowing conditions. Nitric acid was observed in the 1660-1760/cm range, while nitrogen dioxide was detected both in the 1536-1660 and 1213-1400/cm ranges. Concentrations of nitrogen dioxide and nitric acid were determined to be 11.9 and 4.35 parts per million (ppm), respectively, with an uncertainty of 0.2 ppm. Experiments are underway with a 10 m cell to measure the absorption of nitric acid, water, sulfur dioxide, hydrochloric acid and ammonia on various materials such as glass, teflon, stainless steel and aluminum used for implementation of the flow system. Such materials will be used for the measurements of stratospheric trace gases by the Quartz Crystal Microbalance (QCM) and Surface Acoustic Wave (SAW) devices.

  6. Observations of lower-stratospheric ClONO2, HNO3, and aerosol by the UARS CLAES experiment between January 1992 and April 1993

    NASA Technical Reports Server (NTRS)

    Roche, A. E.; Kumer, J. B.; Mergenthaler, J. L.; Nightingale, R. W.; Uplinger, W. G.; Ely, G. A.; Potter, J. F.; Wuebbles, D. J.; Connell, P. S.; Kinnison, D. E.

    1994-01-01

    This paper discusses simultaneous measurements of stratospheric ClONO2, HNO3, temperature, and aerosol extinction coefficient by the Cryogenic Limb Array Etalon Spectrometer (CLAES) on the NASA Upper Atmosphere Research Satellite (UARS), obtained over the period 9 January 1992 through 23 April 1993. The discussion concentrates on the stratosphere region near 21 km of particular interest to heterogeneously driven ozone depletion. For periods between 12 June and 1 September 1992 at latitudes poleward of about 60 deg S, when temperatures were below type I polar stratospheric cloud (PSC) formation thresholds throughout the lower stratosphere, CLAES observed high levels of PSCs coincident with highly depleted fields of both HNO3 and ClONO2. By 17 September, the incidence of PSCs had greatly diminished in the lower stratosphere, but both CLONO2 and HNO3 remained highly depleted. These observations are consistent with the removal of gaseous HNO3 through the formation of nitric acid trihydrate (NAT) particles and the removal of ClONO2 through heterogeneous reactions on the particle surfaces. They also suggest substantial denitrification of the lower Antarctic vortex through sedimentation of PSC particles. In the Northern Hemisphere winter of 1992/93 far fewer PSCs were observed in the Arctic lower-stratosphere vortex, which had shorter periods and more localized regions of cold temperatures. Both HNO3 and ClONO2 maintained much higher levels inside the Arctic vortex than seen in the Antarctic throughout the winter/spring period. Following 28 February 1993 when Arctic vortex temperatures rose above 195 K, ClONO2 was observed in large quantities (greater than 2.1 ppbv near 21 km) inside the vortex. The persistence of relatively high levels of HNO3 inside the Arctic spring vortex compared with the low levels seen in the Antarctic spring vortex suggest a much lower level of denitrification in the Arctic.

  7. Enhanced Haze Ratio on Glass by Novel Vapor Texturing Method.

    PubMed

    Lee, Seunghwan; Balaji, Nagarajan; Ju, Minkyu; Park, Cheolmin; Kim, Jungmo; Chung, Sungyoun; Lee, Youn-Jung

    2016-05-01

    State-of-the-art optical trapping designs are required to enhance the light trapping capabilities of tandem thin film silicon solar cells. The wet etch process is used to texture the glass surface by dipping in diluted acidic solutions such as HNO3 (nitric acid) and HF (hydrofluoric acid). For vapor texturing, the vapor was generated by adding silicon to HF:HNO3 acidic solution. The anisotropic etching of vapor textured wafers resulted in an etching depth of about 2.78 μm with reduced reflectance of 5%. We achieved a high haze value of 74.6% at a 540 nm wavelength by increasing the etching time and HF concentration. PMID:27483862

  8. Measurements of HNO3 and N2O5 using ion drift-chemical ionization mass spectrometry during the MILAGRO/MCMA-2006 campaign

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Zhang, R.; Fortner, E. C.; Volkamer, R. M.; Molina, L.; Aiken, A. C.; Jimenez, J. L.; Gaeggeler, K.; Dommen, J.; Dusanter, S.; Stevens, P. S.; Tie, X.

    2008-11-01

    An ion drift-chemical ionization mass spectrometer (ID-CIMS) was deployed in Mexico City between 7 and 31 March to measure gas-phase nitric acid (HNO3) and dinitrogen pentoxide (N2O5 during the Mexico City Metropolitan Area (MCMA)-2006 field campaign. The observation site was located at the Instituto Mexicano del Petróleo in the northern part of Mexico City urban area with major emissions of pollutants from residential, vehicular and industrial sources. Diurnally, HNO3 was less than 200 parts per trillion (ppt) during the night and early morning. The concentration of HNO3 increased steadily from around 09:00 a.m. central standard time (CST), reached a peak value of 0.5 to 3 parts per billion (ppb) in the early afternoon, and then declined sharply to less than half of the peak value near 05:00 p.m. CST. An inter-comparison between the ID-CIMS and an ion chromatograph/mass spectrometer (ICMS) showed a good agreement between the two HNO3 measurements (R2=0.75). The HNO3 mixing ratio was found to anti-correlate with submicron-sized aerosol nitrate, suggesting that the gas-particle partitioning process was a major factor in determining the gaseous HNO3 concentration. Losses by irreversible reactions with mineral dust and via dry deposition also could be important at this site. Most of the times during the MCMA 2006 field campaign, N2O5 was found to be below the detection limit (about 30 ppt for a 10 s integration time) of the ID-CIMS, because of high NO mixing ratio at the surface (>100 ppb) during the night. An exception occurred on 26 March 2006, when about 40 ppt N2O5 was observed during the late afternoon and early evening hours under cloudy conditions before the build-up of NO at the surface site. The results revealed that during the MCMA-2006 field campaign HNO3 was primarily produced from the reaction of OH with NO2 and regulated by gas/particle transfer and dry deposition. The production of HNO3 from N2O5 hydrolysis during the nighttime was small because of

  9. Theoretical study of atmospheric clusters: HNO3:HCl:H2O

    NASA Astrophysics Data System (ADS)

    Gomez, P. C.; Escribano, R. M.; Galvez, O.

    2009-04-01

    Water, nitric acid and hydrogen chloride play an important role in several atmospheric processes, as individual species, and also interacting in the complex reactions related to ozone depletion in polar stratospheric clouds (PSC). The atmospheric importance of the ternary system HCl:HNO3:H2O was recognized long ago [1]. It is also known that HCl attaches to the surface of PSC particles formed by nitric acid hydrates in what can be considered the first step of the heterogeneous reactions leading to the release of the active chlorine molecule [2]. Recently, HCl was detected dissolved in liquid particles with HNO3/H2O by in situ measurements in the Artic stratosphere [3]. The study of simple models including these three species at a high level of theory can be the first step towards the understanding of all possible kinds of bonding and structures that can arise among these molecules, and can constitute the embryo of more complex mixtures with higher amounts of water or variable proportions of their constituents. This kind of calculations have been successfully performed in the past [4,5]. We present in this contribution our results on the structure and spectroscopical properties of the many different ways that these molecules can be bonded in what are predicted to be thermodynamically stable species. The calculations are performed by density functional methods (B3LYP) using Dunning's quadruple-zeta augmented correlated consisted basis sets (aug-cc-pVQZ). This work has been supported by the Spanish Ministry of Education, Projects FIS2007-61686 and CTQ2008-02578/BQU. We wish to thank also CESGA (Centro de Supercomputacion de Galicia), where some of these calculations were carried out. References: [1] O. B. Toon, P. Hamill, R. P. Turco, J. Pinto. Geophys. Res. Lett. 1986, 13, 1284. [2] Molina, M. J.; Zhang, R.; Wooldridge, P. J.; McMahon, J. R.; Kim, J. E.; Chang, H. Y.; Beyer, K. D. Science 1993, 261,1418. [3] C. Weiser, K. Mauersberger, J. Schreiner, N. Larsen, F

  10. Dissolution behavior of 304 stainless steel in HNO3/HF mixtures

    NASA Astrophysics Data System (ADS)

    Covino, B. S.; Scalera, J. V.; Driscoll, T. J.; Carter, J. P.

    1986-01-01

    The dissolution behavior of type 304 stainless steel was studied in typical pickling environments in an effort to reduce the unnecessary loss of the critical metals nickel and chromium during the pickling process. Dissolution rates were determined for a 90-minute exposure to HNO3/HF solutions ranging from 0.8 M to 3.5 M HNO3 and 0.5 M to 2.6 M HF at 30°, 50°, 70°, and 90 °C and containing 0 to 0.21 M dissolved Fe, Cr, or Ni. Dissolution rates increased as a function of increasing HNO3 concentration from 0.4 M to 1.5 M HNO3, decreased at higher HNO3 concentrations, and increased with increasing HF concentration. Experiments to determine the effect of temperature on the dissolution reaction gave a lower activation energy for solutions with higher HNO3 concentrations. The dissolved Fe and Cr decreased the dissolution rate of 304 stainless steel, while dissolved Ni had essentially no effect. The Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) studies of films resulting from exposure to several HNO3/HF solutions indicated that the fluoride did not penetrate the thin nonprotective films but remained on the outer surface of the film. The scanning Auger microscopy (SAM) studies indicated that the fluoride was uniformly distributed over the surface. Both the dissolution and surface studies are consistent with a dissolution process which is controlled by reactions occurring either in solution or at the film-solution interface.

  11. Unveiling the shape-diversified silicon nanowires made by HF/HNO3 isotropic etching with the assistance of silver

    NASA Astrophysics Data System (ADS)

    Chen, Chia-Yun; Wong, Ching-Ping

    2014-12-01

    Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag+-ion containing oxidants on Si etching, we have re-examined the state-of-the-art metal-assisted chemical etching (MaCE) using HF/AgNO3 etchants. In contrast with previous reports, we found that the interplay of hole injections from Ag+ and NO3- ions to the valence band of Si collectively contributes to the unidirectional dissolution of Si. Finally, we explored the engineering of the Ag nano-seeds to regularize the orientation of the etched nanowires formed on non-Si (100) wafers, which further provides a reliable pathway for constructing the desired morphologies of one-dimensional Si nanostructures regardless of wafer orientation.Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag

  12. Investigation of Interfacial and Bulk Dissociation of HBr, HCl, and HNO3 Using Density Functional Theory-Based Molecular Dynamics Simulations

    SciTech Connect

    Baer, Marcel; Tobias, Douglas J.; Mundy, Christopher J.

    2014-12-18

    In this study we investigate the free energy barrier associated with the dissociation of strong acids, XH (HBr, HCl and HNO3) deprotonation, and subsequent formation of ionpairs, X–___H3O+ in the vicinity of the air-water interface. We will show that the free energy for acid dissociation for HCl and HNO3 show significant differences at the air-water than under bulk solvation conditions producing a picture where at the interface associated molecular species can be stable. For the strongest acid we consider, HBr the more traditional picture of acids is preserved in the vicinity of the air-water interface. Our results have implications for our understanding of acids, and their surface tensions at the air-water interface.

  13. Study of the laser-induced decomposition of HNO3/ 2-Nitropropane mixture at static high pressures

    NASA Astrophysics Data System (ADS)

    Bouyer, Viviane; Hébert, Philippe; Doucet, Michel

    2007-06-01

    HNO3 / 2-Nitropropane is a well known energetic material on which Raman spectroscopy measurements at static high pressure in a diamond anvil cell (DAC) have already been conducted at CEA/LE RIPAULT in order to examine the evolution of the mixture as a function of composition and pressure [1]. The purpose of the work presented here was to study the laser-induced decomposition of these energetic materials at static high pressures by measuring the combustion front propagation rate in the DAC. First of all, the feasibility of the experimental device was checked with a well known homogeneous explosive, nitromethane. Our results were consistent with those of Rice and Foltz [2]. Then, we investigated the initiation of NA / 2NP mixture as a function of nitric acid proportion, for a given pressure. We chose the mixture for which both the combustion propagation rate and detonation velocity are maximum and we examined the evolution of the front propagation velocity as a function of pressure and energy deposit. [1] Hebert, P., Regache, I., and Lalanne, P., ``High-Pressure Raman Spectroscopy study of HNO3 / 2-Nitropropane Mixtures. Influence of the Composition.'' Proceedings of the 42nd European High-Pressure Research Group Meeting, Lausanne, Suisse, 2004 [2] Rice, S.F., et al., Combustion and Flame 87 (1991) 109-122.

  14. Theoretical study of atmospheric clusters: HNO3-HCl-H2O.

    PubMed

    Gómez, P C; Gálvez, O; Escribano, R

    2009-11-14

    Nitric acid, hydrochloric acid and water can form stable aggregates with atmospheric implications, for instance at the surface of polar stratospheric clouds. The structure, stability and chemical properties of these ternary complexes are studied by means of high level theoretical calculations (hybrid DFT B3LYP method along with aug-cc-pVQZ basis set). From the many possible systems that these molecules could form, only 15 are found to yield stable structures, well characterized by a minimum in their potential energy surfaces. These aggregates are studied in detail. They can be collected in three families, according to the role played by each species in the different hydrogen bonding links that result and provide the basis for the stabilization of the clusters. Water and HCl can be H-donors to almost every O atom of HNO(3), which in turn can donate its H atom to the other two molecules. Two special cases are found, one in which H(2)O plays a central role, and another with a three-dimensional structure, in contrast to the basically planar frame of the other clusters. Bonding properties are investigated for the whole series using AIM methods. The elongation of the H-Cl bond as a consequence of the aggregate creation is inspected in detail, as it may provide a clue to the lability of this molecule with implications in atmospheric processes. The Gibbs free energy calculated for these clusters shows that some of them could form spontaneously in the range of temperatures of the stratosphere.

  15. Simultaneous Observations fo Polar Stratospheric Clouds and HNO3 over Scandinavia in January, 1992

    NASA Technical Reports Server (NTRS)

    Massie, S. T.; Santee, M. L.; Read, W. G.; Grainger, R. G.; Lambert, A.; Mergenthaler, J. L.; Dye, J. E.; Baumbardner, D.; Randel, W. J.; Tabazadeh, A.; Tie, X.; Pan, L.; Figarol, F.; Wu, F.; Brasseur, G. P.

    1996-01-01

    Simultaneous observations of Polar Stratospheric Cloud aerosol extinction and HNO3 mixing ratios over Scandinavia are examined for January 9-10, 1992. Data measured by the Microwave Limb Sounder (MLS), Cryogenic Limb Array Etalon, Spectrometer (CLAES), and Improved Stratospheric and Mesospheric Sounder (ISAMA) experiments on the Upper Atmosphere Research Satellite (UARS) are examined at locations adjacent to parcel trajectory positions.

  16. Kinetics of Acid-Catalyzed Dehydration of Cyclic Hemiacetals in Organic Aerosol Particles in Equilibrium with Nitric Acid Vapor.

    PubMed

    Ranney, April P; Ziemann, Paul J

    2016-04-28

    Previous studies have shown that 1,4-hydroxycarbonyls, which are often major products of the atmospheric oxidation of hydrocarbons, can undergo acid-catalyzed cyclization and dehydration in aerosol particles to form highly reactive unsaturated dihydrofurans. In this study the kinetics of dehydration of cyclic hemiacetals, the rate-limiting step in this process, was investigated in a series of environmental chamber experiments in which secondary organic aerosol (SOA) containing cyclic hemiacetals was formed from the reaction of n-pentadecane with OH radicals in dry air in the presence of HNO3. A particle beam mass spectrometer was used to monitor the formation and dehydration of cyclic hemiacetals in real time, and SOA and HNO3 were quantified in filter samples by gravimetric analysis and ion chromatography. Measured dehydration rate constants increased linearly with increasing concentration of HNO3 in the gas phase and in SOA, corresponding to catalytic rate constants of 0.27 h(-1) ppmv(-1) and 7.0 h(-1) M(-1), respectively. The measured Henry's law constant for partitioning of HNO3 into SOA was 3.7 × 10(4) M atm(-1), ∼25% of the value for dissolution into water, and the acid dissociation constant was estimated to be <8 × 10(-4), at least a factor of 10(4) less than that for HNO3 in water. The results indicate that HNO3 was only weakly dissociated in the SOA and that dehydration of cyclic hemiacetals was catalyzed by molecular HNO3 rather than by H(+). The Henry's law constant and kinetics relationships measured here can be used to improve mechanisms and models of SOA formation from the oxidation of hydrocarbons in dry air in the presence of NOx, which are conditions commonly used in laboratory studies. The fate of cyclic hemiacetals in the atmosphere, where the effects of higher relative humidity, organic/aqueous phase separation, and acid catalysis by molecular H2SO4 and/or H(+) are likely to be important, is discussed. PMID:27043733

  17. Kinetics of Acid-Catalyzed Dehydration of Cyclic Hemiacetals in Organic Aerosol Particles in Equilibrium with Nitric Acid Vapor.

    PubMed

    Ranney, April P; Ziemann, Paul J

    2016-04-28

    Previous studies have shown that 1,4-hydroxycarbonyls, which are often major products of the atmospheric oxidation of hydrocarbons, can undergo acid-catalyzed cyclization and dehydration in aerosol particles to form highly reactive unsaturated dihydrofurans. In this study the kinetics of dehydration of cyclic hemiacetals, the rate-limiting step in this process, was investigated in a series of environmental chamber experiments in which secondary organic aerosol (SOA) containing cyclic hemiacetals was formed from the reaction of n-pentadecane with OH radicals in dry air in the presence of HNO3. A particle beam mass spectrometer was used to monitor the formation and dehydration of cyclic hemiacetals in real time, and SOA and HNO3 were quantified in filter samples by gravimetric analysis and ion chromatography. Measured dehydration rate constants increased linearly with increasing concentration of HNO3 in the gas phase and in SOA, corresponding to catalytic rate constants of 0.27 h(-1) ppmv(-1) and 7.0 h(-1) M(-1), respectively. The measured Henry's law constant for partitioning of HNO3 into SOA was 3.7 × 10(4) M atm(-1), ∼25% of the value for dissolution into water, and the acid dissociation constant was estimated to be <8 × 10(-4), at least a factor of 10(4) less than that for HNO3 in water. The results indicate that HNO3 was only weakly dissociated in the SOA and that dehydration of cyclic hemiacetals was catalyzed by molecular HNO3 rather than by H(+). The Henry's law constant and kinetics relationships measured here can be used to improve mechanisms and models of SOA formation from the oxidation of hydrocarbons in dry air in the presence of NOx, which are conditions commonly used in laboratory studies. The fate of cyclic hemiacetals in the atmosphere, where the effects of higher relative humidity, organic/aqueous phase separation, and acid catalysis by molecular H2SO4 and/or H(+) are likely to be important, is discussed.

  18. Observations of total RONO2 over the boreal forest: NOx sinks and HNO3 sources

    NASA Astrophysics Data System (ADS)

    Browne, E. C.; Min, K.-E.; Wooldridge, P. J.; Apel, E.; Blake, D. R.; Brune, W. H.; Cantrell, C. A.; Cubison, M. J.; Diskin, G. S.; Jimenez, J. L.; Weinheimer, A. J.; Wennberg, P. O.; Wisthaler, A.; Cohen, R. C.

    2013-05-01

    In contrast with the textbook view of remote chemistry where HNO3 formation is the primary sink of nitrogen oxides, recent theoretical analyses show that formation of RONO2 (ΣANs) from isoprene and other terpene precursors is the primary net chemical loss of nitrogen oxides over the remote continents where the concentration of nitrogen oxides is low. This then increases the prominence of questions concerning the chemical lifetime and ultimate fate of ΣANs. We present observations of nitrogen oxides and organic molecules collected over the Canadian boreal forest during the summer which show that ΣANs account for ~20% of total oxidized nitrogen and that their instantaneous production rate is larger than that of HNO3. This confirms the primary role of reactions producing ΣANs as a control over the lifetime of NOx (NOx = NO + NO2) in remote, continental environments. However, HNO3 is generally present in larger concentrations than ΣANs indicating that the atmospheric lifetime of ΣANs is shorter than the HNO3 lifetime. We investigate a range of proposed loss mechanisms that would explain the inferred lifetime of ΣANs finding that in combination with deposition, two processes are consistent with the observations: (1) rapid ozonolysis of isoprene nitrates where at least ~40% of the ozonolysis products release NOx from the carbon backbone and/or (2) hydrolysis of particulate organic nitrates with HNO3 as a product. Implications of these ideas for our understanding of NOx and NOy budget in remote and rural locations are discussed.

  19. Observations of total RONO2 over the boreal forest: NOx sinks and HNO3 sources

    NASA Astrophysics Data System (ADS)

    Browne, E. C.; Min, K.-E.; Wooldridge, P. J.; Apel, E.; Blake, D. R.; Brune, W. H.; Cantrell, C. A.; Cubison, M. J.; Diskin, G. S.; Jimenez, J. L.; Weinheimer, A. J.; Wennberg, P. O.; Wisthaler, A.; Cohen, R. C.

    2013-01-01

    In contrast with the textbook view of remote chemistry where HNO3 formation is the primary sink of nitrogen oxides, recent theoretical analyses show that formation of RONO2 (ΣANs) from isoprene and other terpene precursors is the primary net chemical loss of nitrogen oxides over the remote continents where the concentration of nitrogen oxides is low. This then increases the prominence of questions concerning the chemical lifetime and ultimate fate of ΣANs. We present observations of nitrogen oxides and organic molecules collected over the Canadian boreal forest during the summer that show that ΣANs account for ~ 20% of total oxidized nitrogen and that their instantaneous production rate is larger than that of HNO3. This confirms the primary role of reactions producing ΣANs as a control over the lifetime of NOx (NOx = NO + NO2) in remote, continental environments. However, HNO3 is generally present in larger concentrations than ΣANs indicating that the atmospheric lifetime of ΣANs is shorter than the HNO3 lifetime. We investigate a range of proposed loss mechanisms that would explain the inferred lifetime of ΣANs finding that in combination with deposition, two processes are consistent with the observations: (1) rapid ozonolysis of isoprene nitrates where at least ~ 40% of the ozonolysis products release NOx from the carbon backbone and/or (2) hydrolysis of particulate organic nitrates with HNO3 as a product. Implications of these ideas for our understanding of NOx and NOy budget in remote and rural locations are discussed.

  20. Relative stabilities of HCl•H2SO4•HNO3 aggregates in polar stratospheric clouds.

    PubMed

    Verdes, Marian; Paniagua, M

    2015-04-01

    Strong acids such as HCl (C), HNO3 (N) and H2SO4 (S) acquire relevance in Polar Stratospheric Clouds (PSCs) and aerosols in which nucleation processes occur. Ab initio quantum chemical studies of aggregates were performed for these strong acids. Structures were calculated using DFT methods with the B3LYP hybrid functional and aug-cc-pVTZ basis set. As an initial constraint, an H2SO4 moiety was placed in all candidate structures. A total of 11 optimized structures was found: a global minimum (CSN-a) plus ten local minima on the Potential Energy Surface (PES). The global minimum aggregate gave four hydrogen bonds, yielding a hexagonal ring in its structure. HNO3 acts as proton donor in all clusters; nevertheless, using trans-H2SO4 as the proton donor yielded the most stable structures, whereas HCl acts mainly as a proton donor/acceptor. Real harmonic frequencies, IR spectra, and inter-monomeric parameters were obtained. CSN-a symmetric stretching modes were shifted to 2805.56 cm(-1) and 3520.00 cm(-1) for H-Cl modes, while O-H modes shifted to 3256.87 cm(-1) and 3362.47 cm(-1). On the other hand, relative stabilities improved for 5 of the 11 aggregates when the temperature decreased from 298 K to 210 K, 195 K and 188 K. The aggregate CSN-f remained unstable only at 210 K. Moreover, the relative Gibbs free energy, ΔG(0-298K) was -9.26 kcalmol(-1) with respect to CSN-a; relative reaction Gibbs free energy [Δ(ΔG)] values ranged from 0.0 at 298 K, to -6.9 kcalmol(-1) at 188 K. It seems that CSN aggregates remain slightly more stable than CNS aggregates with a HNO3 moiety when the temperature decreases from 298 to 188 K. Five structures remained relatively stable under both study conditions.

  1. Aerodynamic gradient measurements of the NH3-HNO3-NH4NO3 triad using a wet chemical instrument: an analysis of precision requirements and flux errors

    NASA Astrophysics Data System (ADS)

    Wolff, V.; Trebs, I.; Ammann, C.; Meixner, F. X.

    2010-02-01

    The aerodynamic gradient method is widely used for flux measurements of ammonia, nitric acid, particulate ammonium nitrate (the NH3-HNO3-NH4NO3 triad) and other water-soluble reactive trace compounds. The surface exchange flux is derived from a measured concentration difference and micrometeorological quantities (turbulent exchange coefficient). The significance of the measured concentration difference is crucial for the significant determination of surface exchange fluxes. Additionally, measurements of surface exchange fluxes of ammonia, nitric acid and ammonium nitrate are often strongly affected by phase changes between gaseous and particulate compounds of the triad, which make measurements of the four individual species (NH3, HNO3, NH4+, NO3- necessary for a correct interpretation of the measured concentration differences. We present here a rigorous analysis of results obtained with a multi-component, wet-chemical instrument, able to simultaneously measure gradients of both gaseous and particulate trace substances. Basis for our analysis are two field experiments, conducted above contrasting ecosystems (grassland, forest). Precision requirements of the instrument as well as errors of concentration differences and micrometeorological exchange parameters have been estimated, which, in turn, allows the establishment of thorough error estimates of the derived fluxes of NH3, HNO3, NH4+, and NO3-. Derived median flux errors for the grassland and forest field experiments were: 39% and 50% (NH3), 31% and 38% (HNO3), 62% and 57% (NH4+), and 47% and 68% (NO3-), respectively. Additionally, we provide the basis for using field data to characterize the instrument performance, as well as subsequent quantification of surface exchange fluxes and underlying mechanistic processes under realistic ambient measurement conditions.

  2. Aerodynamic gradient measurements of the NH3-HNO3-NH4NO3 triad using a wet chemical instrument: an analysis of precision requirements and flux errors

    NASA Astrophysics Data System (ADS)

    Wolff, V.; Trebs, I.; Ammann, C.; Meixner, F. X.

    2009-10-01

    The aerodynamic gradient method is widely used for flux measurements of ammonia, nitric acid, particulate ammonium nitrate (the NH3-HNO3-NH4NO3 triad) and other water-soluble reactive trace compounds. The surface exchange flux is derived from a measured concentration difference and micrometeorological quantities (turbulent exchange coefficient). The significance of the measured concentration difference is crucial for the significant determination of surface exchange fluxes. Additionally, measurements of surface exchange fluxes of ammonia, nitric acid and ammonium nitrate are often strongly affected by phase changes between gaseous and particulate compounds of the triad, which make measurements of the four individual species (NH3, HNO3, NH4+, NO3-) necessary for a correct interpretation of the measured concentration differences. We present here a rigorous analysis of results obtained with a multi-component, wet-chemical instrument, able to simultaneously measure gradients of both gaseous and particulate trace substances. Basis for our analysis are two field experiments, conducted above contrasting ecosystems (grassland, forest). Precision requirements of the instrument as well as errors of concentration differences and micrometeorological exchange parameters have been estimated, which, in turn, allows the establishment of thorough error estimates of the derived fluxes of NH3, HNO3, NH4+, and NO3-. Derived median flux errors for the grassland and forest field experiments were: 39 and 50% (NH3), 31 and 38% (HNO3), 62 and 57% (NH4+), and 47 and 68% (NO3-), respectively. Additionally, we provide the basis for using field data to characterize the instrument performance, as well as subsequent quantification of surface exchange fluxes and underlying mechanistic processes under realistic ambient measurement conditions.

  3. Quantum chemical study of atmospheric aggregates: HCl•HNO3•H2SO4.

    PubMed

    Verdes, Marian; Paniagua, Miguel

    2014-06-01

    HCl, HNO3 and H2SO4 are implicated in atmospheric processes in areas such as polar stratospheric clouds in the stratosphere. Ternary complexes of HCl, HNO3 and H2SO4 were investigated by ab initio calculations at B3LYP level of theory with aug-cc-pVTZ and aug-cc-pVQZ basis sets, taking into account basis set superposition error (BSSE). The results were assessed in terms of structures (five hexagonal cyclic structures and two quasi-pentagonal cyclic structures), inter-monomeric parameters (all ternary complexes built three hydrogen bonds), energetics (seven minima obtained), infrared harmonic vibrational frequencies (red shifting of complexes from monomers), and relative stability of complexes, which were favorable when the temperature decreases under stratospheric conditions, from 298 K to 188 K, and in concrete, at 210 K, 195 K and 188 K. PMID:24844391

  4. Quantum chemical study of atmospheric aggregates: HCl•HNO3•H2SO4.

    PubMed

    Verdes, Marian; Paniagua, Miguel

    2014-06-01

    HCl, HNO3 and H2SO4 are implicated in atmospheric processes in areas such as polar stratospheric clouds in the stratosphere. Ternary complexes of HCl, HNO3 and H2SO4 were investigated by ab initio calculations at B3LYP level of theory with aug-cc-pVTZ and aug-cc-pVQZ basis sets, taking into account basis set superposition error (BSSE). The results were assessed in terms of structures (five hexagonal cyclic structures and two quasi-pentagonal cyclic structures), inter-monomeric parameters (all ternary complexes built three hydrogen bonds), energetics (seven minima obtained), infrared harmonic vibrational frequencies (red shifting of complexes from monomers), and relative stability of complexes, which were favorable when the temperature decreases under stratospheric conditions, from 298 K to 188 K, and in concrete, at 210 K, 195 K and 188 K.

  5. Arsenic bioaccessibility in contaminated soils: Coupling in vitro assays with sequential and HNO3 extraction.

    PubMed

    Li, Shi-Wei; Li, Jie; Li, Hong-Bo; Naidu, Ravi; Ma, L Q

    2015-09-15

    Arsenic bioaccessibility varies with in vitro methods and soils. Four assays including unified BARGE method (UBM), Solubility Bioaccessibility Research Consortium method (SBRC), in vitro gastrointestinal method (IVG), and physiologically based extraction test (PBET), were used to determine As bioaccessibility in 11 contaminated soils (22-4,172 mg kg(-1)). The objective was to understand how bioaccessible As by different methods was related to different As pools based on sequential extraction and 0.43 M HNO3 extraction. Arsenic bioaccessibility was 7.6-25, 2.3-49, 7.3-44, and 1.3-38% in gastric phase (GP), and 5.7-53, 0.46-33, 2.3-42, and 0.86-43% in intestinal phase (IP) for UBM, SBRC, IVG, and PBET, respectively, with HNO3-extractable As being 0.90-60%. Based on sequential extraction, As was primarily associated with amorphous (AF3; 17-79%) and crystallized Fe/Al oxides (CF4; 6.4-73%) while non-specifically sorbed (NS1), specifically sorbed (SS2), and residual fractions (RS5) were 0-10%, 3.4-20% and 3.2-25%. Significant correlation was found between As bioaccessibility by PBET and NS1+SS2 (R(2) = 0.55-0.69), and UBM-GP and NS1 + SS2 + AF3 (R(2) = 0.58), indicating PBET mostly targeted As in NS1+SS2 whereas UBM in NS1 + SS2 + AF3. HNO3-extractable As was correlated to bioaccessible As by four methods (R(2) = 0.42-0.72) with SBRC-GP having the best correlation. The fact that different methods targeted different As fractions in soils suggested the importance of validation by animal test. Our data suggested that HNO3 may have potential to determine bioaccessible As in soils. PMID:25897696

  6. Simulations of the Vertical Redistribution of HNO3 by NAT or NAD PSCs: The Sensitivity to the Number of Cloud Particles Formed and the Cloud Lifetime

    NASA Technical Reports Server (NTRS)

    Jensen, Eric J.; Tabazadeh, Azadeh; Drdla, Katja; Toon, Owen B.; Gore, Warren J. (Technical Monitor)

    2000-01-01

    Recent satellite and in situ measurements have indicated that limited denitrification can occur in the Arctic stratosphere. In situ measurements from the SOLVE campaign indicate polar stratospheric clouds (PSCs) composed of small numbers (about 3 x 10^ -4 cm^-3) of 10-20 micron particles (probably NAT or NAD). These observations raise the issue of whether low number density NAT PSCs can substantially denitrify the air with reasonable cloud lifetimes. In this study, we use a one dimensional cloud model to investigate the verticle redistribution of HNO3 by NAT/NAD PSCs. The cloud formation is driven by a temperature oscillation which drops the temperature below the NAT/NAD formation threshold (about 195 K) for a few days. We assume that a small fraction of the available aerosols act as NAT nuclei when the saturation ratio of HNO3 over NAT(NAD) exceeds 10(l.5). The result is a cloud between about 16 and 20 km in the model, with NAT/NAD particle effective radii as large as about 10 microns (in agreement with the SOLVE data). We find that for typical cloud lifetimes of 2-3 days or less, the net depletion of HNO3 is no more than 1-2 ppbv, regardless of the NAT or NAD particle number density. Repeated passes of the air column through the cold pool build up the denitrification to 3-4 ppbv, and the cloud altitude steadily decreases due to the downward transport of nitric acid. Increasing the cloud lifetime results in considerably more effective denitrification, even with very low cloud particle number densities. As expected, the degree of denitrification by NAT clouds is much larger than that by NAD Clouds. Significant denitrification by NAD Clouds is only possible if the cloud lifetime is several days or more. The clouds also cause a local maximum HNO3 mixing ratio at cloud base where the cloud particles sublimate.

  7. Can laboratory data explain field observations: The fluxes of HNO3 and HNO4 from snow in the lab and in Antarctica

    NASA Astrophysics Data System (ADS)

    Bartels-Rausch, Thorsten

    2015-04-01

    equilibrium partitioning of HNO3 and HNO4 that one would expect based on selected laboratory data. Both, adsorption to the surface of the snow and uptake to the bulk forming a solid solution are discussed (HNO3 only). Further, I address the question, if the snow holds enough HNO3 and HNO4 at its surface or in its bulk (HNO3 only) to fuel the observed emissions. Thus both equilibrium conditions and molecular flux budgets are discussed. These calculations show that adsorption/desorption can indeed explain the observed mixing ratio in the Antarctic boundary layer. Release from a solid solution seems to be too slow. Jones, A. E., Brough, N., Anderson, P. S., & Wolff, E. W. (2014). HO2NO2 and HNO3 in the coastal Antarctic winter night: a "lab-in-the-field" experiment. Acpd, 14(9), 12771-12796. Interactive comment on "HO2NO2 and HNO3 in the coastal Antarctic winter night: a "lab-in-the-field" experiment" by A. E. Jones et al. , T. Bartels-Rausch thorsten.bartels-rausch@psi.ch Received and published: 11 July 2014 Legrand, M., Preunkert, S., Frey, M., Bartels-Rausch, T., Kukui, A., King, M. D., et al. (2014). Large mixing ratios of atmospheric nitrous acid (HONO) at Concordia (East Antarctic plateau) in summer: a strong source from surface snow? Atmospheric Chemistry and Physics Discussions, 14(8), 11749-11785. doi:10.5194/acpd-14-11749-2014 Ulrich, T., Ammann, M., Leutwyler, S., & Bartels-Rausch, T. (2012). The adsorption of peroxynitric acid on ice between 230 K and 253 K. Atmospheric Chemistry and Physics, 12(4), 1833-1845. doi:10.5194/acp-12-1833-2012

  8. Temperature dependence of HNO3 absorption in the 11.3-micron region

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Bonomo, F. S.; Valero, F. P. J.; Goorvitch, D.; Boese, R. W.

    1981-01-01

    Laboratory spectra have been obtained for HNO3 with a Michelson-type Fourier transform interferometer using absorption cells with path lengths of 10.3, 25.5, and 49.8 cm at temperatures of 240, 248, 283, and 294 K. The measurements lead to a total band intensity value of 642 plus or minus 5% per sq cm amagat, which is a temperature independent value after the gas density correction has been made. However, the temperature dependence of the spectral absorption coefficients is apparent in the 885 kayser region.

  9. Materials compatibility for 238Pu-HNO3/HF solution containment: 238Pu aqueous processing

    NASA Astrophysics Data System (ADS)

    Reimus, M. A.; Pansoy-Hjelvik, M. E.; Silver, G.; Brock, J.; Nixon, J.; Ramsey, K. B.; Moniz, P.

    2000-07-01

    The Power Source Technologies Group at Los Alamos National Laboratory is building a 238Pu Aqueous Scrap Recovery Line at the Plutonium Facility. The process line incorporates several unit operations including dissolution, filtration, ion exchange, and precipitation. During 1997-1999, studies were carried out to determine the chemistry used in the full-scale process. Other studies focussed on the engineering design of the operation. Part of the engineering design was to determine, in compatibility studies, the materials for reaction and storage vessels which will contain corrosive 238Pu-HNO3/HF solutions. The full-scale line is to be operational by the end of year 2000.

  10. Nitric acid vapor removal by activated, impregnated carbons

    SciTech Connect

    Wood, G.O.

    1996-12-31

    Laboratory and industrial workers can be exposed to vapors of nitric acid, especially in accidents, such as spills. Nitric acid can also be a product of incineration for energy production or waste (e.g., CW agent) disposal. Activated carbons containing impregnants for enhancing vapor and gas removal have been tested for effectiveness in removing vapors of nitric acid from air. The nitric acid vapor was generated from concentrated acid solutions and detected by trapping in a water bubbler for pH measurements. Both low and moderate relative humidity conditions were used. All carbons were effective at vapor contact times representative of air-purifying respirator use. One surprising observation was the desorption of low levels of ammonia from impregnated carbons. This was apparently due to residual ammonia from the impregnation processes.

  11. Evidence that nitric acid increases relative humidity in low-temperature cirrus clouds.

    PubMed

    Gao, R S; Popp, P J; Fahey, D W; Marcy, T P; Herman, R L; Weinstock, E M; Baumgardner, D G; Garrett, T J; Rosenlof, K H; Thompson, T L; Bui, P T; Ridley, B A; Wofsy, S C; Toon, O B; Tolbert, M A; Kärcher, B; Peter, Th; Hudson, P K; Weinheimer, A J; Heymsfield, A J

    2004-01-23

    In situ measurements of the relative humidity with respect to ice (RHi) and of nitric acid (HNO3) were made in both natural and contrail cirrus clouds in the upper troposphere. At temperatures lower than 202 kelvin, RHi values show a sharp increase to average values of over 130% in both cloud types. These enhanced RHi values are attributed to the presence of a new class of HNO3-containing ice particles (Delta-ice). We propose that surface HNO3 molecules prevent the ice/vapor system from reaching equilibrium by a mechanism similar to that of freezing point depression by antifreeze proteins. Delta-ice represents a new link between global climate and natural and anthropogenic nitrogen oxide emissions. Including Delta-ice in climate models will alter simulated cirrus properties and the distribution of upper tropospheric water vapor.

  12. Evidence that nitric acid increases relative humidity in low-temperature cirrus clouds.

    PubMed

    Gao, R S; Popp, P J; Fahey, D W; Marcy, T P; Herman, R L; Weinstock, E M; Baumgardner, D G; Garrett, T J; Rosenlof, K H; Thompson, T L; Bui, P T; Ridley, B A; Wofsy, S C; Toon, O B; Tolbert, M A; Kärcher, B; Peter, Th; Hudson, P K; Weinheimer, A J; Heymsfield, A J

    2004-01-23

    In situ measurements of the relative humidity with respect to ice (RHi) and of nitric acid (HNO3) were made in both natural and contrail cirrus clouds in the upper troposphere. At temperatures lower than 202 kelvin, RHi values show a sharp increase to average values of over 130% in both cloud types. These enhanced RHi values are attributed to the presence of a new class of HNO3-containing ice particles (Delta-ice). We propose that surface HNO3 molecules prevent the ice/vapor system from reaching equilibrium by a mechanism similar to that of freezing point depression by antifreeze proteins. Delta-ice represents a new link between global climate and natural and anthropogenic nitrogen oxide emissions. Including Delta-ice in climate models will alter simulated cirrus properties and the distribution of upper tropospheric water vapor. PMID:14739457

  13. Composition-dependent freezing nucleation rates for HNO3/H2O aerosols resembling gravity-wave-perturbed stratospheric particles

    NASA Astrophysics Data System (ADS)

    Prenni, Anthony J.; Onasch, Timothy B.; Tisdale, Robert T.; Siefert, Ronald L.; Tolbert, Margaret A.

    1998-11-01

    Laboratory measurements are presented for the freezing kinetics of H2O/HNO3 aerosols over the temperature range of 188-204 K. For 2:1 H2O:HNO3 aerosols crystallizing to NAD we observed a maximum nucleation rate of J = 9.3×109 cm-3 s-1 at 194 K. This temperature is between the glass point of 161 K [Ji et al., 1993] and the melting point of 235.5 K [Ji et al., 1996]. This can be compared to a previous measurement of J = 6.7×109 cm-3 s-1 at 193 K [Disselkamp et al., 1996] and lower temperature measurements of J ≈ 1010-1012 cm-3 s-1 at 178.8 - 175.8 K [Bertram and Sloan, 1998a]. Measured nucleation rates decrease as the aerosol becomes dilute, but NAD formation is still observable for 2.5:1 H2O:HNO3 at temperatures near 195 K. In contrast, freezing of 3:1 H2O:HNO3 aerosol was not observed for constant temperature experiments throughout this temperature range, yielding an upper limit of J<1.5×109 cm-3 s-1. This is the lowest experimental value determined for 3:1 H2O:HNO3 freezing rates at these temperatures. From the measured freezing rates and knowledge of the free energy of diffusion the average interfacial free energy for NAD in a 2:1 H2O:HNO3 solution was determined to be σ = 25.2 ergs cm-2. A limit for the interfacial free energy was placed on 3:1 H2O:HNO3 particles, for which freezing was not observed. These data imply that if aerosols reach compositions more concentrated than 3:1 H2O:HNO3 in the atmosphere, NAD may play a role in polar stratospheric cloud formation.

  14. Investigation of catalytic reduction and filter techniques for simultaneous measurements of NO, NO2, and HNO3 in the stratosphere

    NASA Technical Reports Server (NTRS)

    Wendt, J.; Fabian, Peter; Flentje, G.; Kourtidis, K.

    1994-01-01

    A concept for measuring stratospheric NOy-species is presented which utilizes the catalytic reduction of NO2 and HNO3 over heated metal catalysts and the chemisorption of HNO3 on Nylon. Using the Max Planck Institute for Aeronomy (MPAE) chemiluminescent balloon-borne sonde, stratospheric NO and NO2 profiles have been measured since 1983. NO is detected by chemiluminescence produced in reaction with O3 while NO2 needs first to be converted to NO over a heated stainless steel catalyst. To improve this technique for simultaneously measuring HNO3, the catalytic reduction of NO2 and HNO3 over several metal catalysts and the chemisorption of NO2 and HNO3 on Nylon have been investigated in laboratory tests. The results of these tests under simulated stratospheric conditions are presented in detail in this paper. They demonstrate that the simultaneous measurement of NO, NO2 and HNO3 is indeed possible with the combination of stainless steel or Au as a catalyst and a nylon filter.

  15. Growth of nitric acid hydrates on thin sulfuric acid films

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Middlebrook, Ann M.; Wilson, Margaret A.; Tolbert, Margaret A.

    1994-01-01

    Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1-3 x 10(exp -4) Torr H2O and 1-2.5 x 10(exp -6) Torr HNO3) and subjected to cooling and heating cycles. Fourier Transform Infrared (FTIR) spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films that condensed. Nitric acid trihydrate (NAT) was observed to grow on crystalline sulfuric acid tetrahydrate (SAT) films. NAT also condensed in/on supercooled H2SO4 films without causing crystallization of the sulfuric acid. This growth is consistent with NAT nucleation from ternary solutions as the first step in PSC formation.

  16. Is NO3/N2O5 chemistry a source of aerosol HNO3 in the San Joaquin Valley?

    NASA Astrophysics Data System (ADS)

    Minejima, C.; Wooldridge, P. J.; Cohen, R. C.

    2009-12-01

    Sensitive and continuous measurements of NO3 + N2O5 concentrations were made at Arvin from March 1 to March 30, 2007 using Thermal Dissociation-Laser Induced Fluorescence (TD-LIF) to investigate the role of NO3 and N2O5 as a cause of high ammonium nitrate (NH4NO3) aerosol concentrations in California’s San Joaquin Valley (SJV). NH4NO3 is produced via a reaction of HNO3 and NH3. And HNO3 is the limiting reagent for NH3 is emitted in large amount from agricultural sources and motor vehicles in the SJV. NO3 and N2O5 play an important part in producing HNO3. Nighttime production of HNO3 through a heterogeneous N2O5 reaction with H2O on aerosol surfaces was investigated by measuring the NO3 + N2O5 concentrations. Peak values of N2O5 mixing ratio often exceeded 100 pptv and ranged between 25-320 pptv. Size resolved particle number was measured to estimate aerosol surface load and it was found that heterogeneous N2O5 reaction with the estimated surface load could explain only up to a few % of HNO3 production. Here the necessary HNO3 production is calculated by assuming the aerosol lifetime with respect to deposition and/or transport out of PBL is 1 day. Other possible passes to produce HNO3 are the day time NO2 + OH reaction, nighttime NO3 + anthropogenic HC reactions, and NO3 + biogenic HC reactions. Contribution of each pass was estimated by auxiliary measurements and knowledge from literature. Daytime HNO3 production was calculated from the measured NO2 concentration at the nearest CARB site and OH concentration from literature to show that it may account for ~25 % of HNO3 required. Total non methane hydrocarbons (NMHCs), which is mostly anthropogenic, is measured at the CARB site. Assuming the similar compositions of NMHCs in Sacramento, NO3 + anthropogenic HCs are calculated to be as fast to explain 40 - 70 % of NO3 + N2O5 loss. HNO3 yield from these reactions are not well known. The upper limit of HNO3 production, however, can be estimated by assuming unity yield

  17. Condensation of acetol and acetic acid vapor with sprayed liquid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A cellulose-derived fraction of biomass pyrolysis vapor was simulated by evaporating acetol and acetic acid (AA) from flasks on a hot plate. The liquid in the flasks was infused with heated nitrogen. The vapor/nitrogen stream was superheated in a tube oven and condensed by contact with a cloud of ...

  18. Heat-Exchange Fluids for Sulfuric Acid Vaporizers

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Petersen, G. R.

    1982-01-01

    Some fluorine-substituted organic materials meet criteria for heat-exchange fluids in contact with sulfuric acid. Most promising of these are perfluoropropylene oxide polymers with degree of polymerization (DP) between 10 and 50. It is desirable to have DP in high range because vapor pressure of material decreases as DP increases, and high-DP liquids have lower loss due to vaporization.

  19. The determination of HNO3 column amounts from tunable diode laser heterodyne spectrometer spectra taken at Jungfruajoch, Switzerland

    NASA Technical Reports Server (NTRS)

    Fogal, P. F.; Murcray, D. G.; Martin, N. A.; Swann, N. R.; Woods, P. T.; Mcelroy, C. T.

    1994-01-01

    In May of 1991 a tunable diode laser heterodyne spectrometer built by the National Physical Laboratory was operated at the International Scientific Station of the Jungfraujoch (46.5 deg N, 8.0 deg E, altitude 3.56 km). Nitric acid spectra in the region of 868 wavenumbers were recorded at sunset and sunrise on two separate days at a resolution of 0.0013 wavenumbers with a signal-to-noise ratio of approximately 130:1. A vertical column amount of HNO3 of 1.61 x 10(exp 16) molecules/sq cm was determined using an atmospheric transmission model developed at the University of Denver. The mean of a number of mid-latitude, northern hemisphere profiles was used as the initial profile for the inversion. A comparison of different initial profiles provides information on the sensitivity of the retrieved column amount of 1.61 x 10(exp 16) molecules/sq cm lies within the range of values published in the World Meteorological Organization Report no. 16 (1986), but is considerably larger than the value of (0.99 - 1.29) x 10(exp 16) reported by Rinsland et al. (1991) for June during the period 1986 to 1990.

  20. Uptake measurements of acetaldehyde on solid ice surfaces and on solid/liquid supercooled mixtures doped with HNO3 in the temperature range 203-253 K.

    PubMed

    Petitjean, M; Mirabel, Ph; Le Calvé, S

    2009-04-30

    Uptake of acetaldehyde on ice surfaces has been investigated over the temperature range 203-253 K using a coated wall flow tube coupled to a mass spectrometric detection. The experiments were conducted on pure ice surfaces and on liquid/solid ice mixture both doped with nitric acid (0.063, 0.63, and 6.3 wt %). Uptake of acetaldehyde on these surfaces was always found to be totally reversible whatever the experimental conditions were. The number of acetaldehyde molecules adsorbed per surface unit was conventionally plotted as a function of acetaldehyde concentration in the gas phase. Although the amounts of acetaldehyde adsorbed on solid ice surfaces (pure and HNO(3)-doped ice) were approximately similar and rather limited, the number of acetaldehyde molecules taken up on the HNO(3)-doped solid ice/liquid mixtures are significantly higher, up to 1 or 2 orders of magnitudes compared to pure ice surfaces. At 213 K for example and for low concentrations of acetaldehyde (<1 x 10(13) molecule cm(-3)), the amount of acetaldehyde molecules taken up on solid/liquid doped surfaces is 3.3 and 8.8 times higher than those measured on pure ice respectively for 0.063 and 0.63 wt % of HNO(3). The huge quantities of acetaldehyde taken up by liquid-/solid-doped mixtures are likely dissolved in the nonhomogeneous liquid part of the surfaces according to the Henry's law equilibrium. As a consequence, up to about 10% of acetaldehyde may be scavenged by supercooled liquid droplets of convective clouds in the upper troposphere.

  1. Phase equilibria of H2SO4, HNO3, and HCl hydrates and the composition of polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Wooldridge, Paul J.; Zhang, Renyi; Molina, Mario J.

    1995-01-01

    Thermodynamic properties and phase equilibria behavior for the hydrates and coexisting pairs of hydrates of common acids which exist in the stratosphere are assembled from new laboratory measurements and standard literature data. The analysis focuses upon solid-vapor and solid-solid-vapor equilibria at temperatures around 200 K and includes new calorimetric and vapor pressure data. Calculated partial pressures versus 1/T slopes for the hydrates and coexisting hydrates agree well with experimental data where available.

  2. Phase Equilibria of H2SO4, HNO3, and HCl Hydrates and the Composition of Polar Stratospheric Clouds

    NASA Technical Reports Server (NTRS)

    Wooldridge, Paul J.; Zhang, Renyi; Molina, Mario J.

    1995-01-01

    Thermodynamic properties and phase equilibria behavior for the hydrates and coexisting pairs of hydrates of common acids which exist in the stratosphere are assembled from new laboratory measurements and standard literature data. The analysis focuses upon solid-vapor and solid-solid-vapor equilibria at temperatures around 200 K and includes new calorimetric and vapor pressure data. Calculated partial pressures versus 1/T slopes for the hydrates and coexisting hydrates agree well with experimental data where available.

  3. Determination of total fluoride in HF/HNO3/H2SiF6 etch solutions by new potentiometric titration methods.

    PubMed

    Weinreich, Wenke; Acker, Jörg; Gräber, Iris

    2007-03-30

    In the photovoltaic industry the etching of silicon in HF/HNO(3) solutions is a decisive process for cleaning wafer surfaces or to produce certain surface morphologies like polishing or texturization. With regard to cost efficiency, a maximal utilisation of etch baths in combination with highest quality and accuracy is strived. To provide an etch bath control realised by a replenishment with concentrated acids the main constituents of these HF/HNO(3) etch solutions including the reaction product H(2)SiF(6) have to be analysed. Two new methods for the determination of the total fluoride content in an acidic etch solution based on the precipitation titration with La(NO(3))(3) are presented within this paper. The first method bases on the proper choice of the reaction conditions, since free fluoride ions have to be liberated from HF and H(2)SiF(6) at the same time to be detected by a fluoride ion-selective electrode (F-ISE). Therefore, the sample is adjusted to a pH of 8 for total cleavage of the SiF(6)(2-) anion and titrated in absence of buffers. In a second method, the titration with La(NO(3))(3) is followed by a change of the pH-value using a HF resistant glass-electrode. Both methods provide consistent values, whereas the analysis is fast and accurate, and thus, applicable for industrial process control. PMID:19071540

  4. The de Haas-van Alphen effect of graphite intercalation compounds with SbCl 5 and HNO 3

    NASA Astrophysics Data System (ADS)

    Takahashi, Otofumi; Iye, Yasuhiro; Tanuma, Sei-ichi

    1981-03-01

    The de Haas-van Alphen (dHvA) effect of SbCl 5-graphite intercalation compounds of stage 2, 3 and 4, and residual HNO 3-compound of stage 3 has been studied. The dHvA spectra are stage dependent, and no combination frequency relations are found, which are in disagreement with Batallan et al.'s report. The amount of charge transfer per intercalant estimated on the basis of the rigid band model is 0.44, 0.49 and 0.43 for stage 4, 3 and 2 SbCl 5-compounds and is 0.14 for stage 3 HNO 3-compound.

  5. Method for the separation of acid from acid-laden vapors

    SciTech Connect

    Hansen, L.J.

    1992-02-11

    This patent describes a method for the removal of hydrochloric or sulfuric acid from vapor laden with the acid. It comprises: contacting the acid-laden vapors with packing materials in a zone containing the packing materials wherein the packing materials are formed of polyester resin containing from about 5 to 40 weight percent aluminum sulfate crystals.

  6. Potential heat exchange fluids for use in sulfuric acid vaporizers

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Petersen, G. R.

    1979-01-01

    A series of perhalocarbons are proposed as candidate heat exchange fluids for service in thermochemical cycles for hydrogen production that involve direct contact of the fluid with sulfuric acid and vaporization of the acid. The required chemical and physical criteria of the liquids are described and the results of some preliminary high temperature test data are presented.

  7. Spectrometric analysis of process etching solutions of the photovoltaic industry--determination of HNO3, HF, and H2SiF6 using high-resolution continuum source absorption spectrometry of diatomic molecules and atoms.

    PubMed

    Bücker, Stefan; Acker, Jörg

    2012-05-30

    The surface of raw multicrystalline silicon wafers is treated with HF-HNO(3) mixtures in order to remove the saw damage and to obtain a well-like structured surface of low reflectivity, the so-called texture. The industrial production of solar cells requires a consistent level of texturization for tens of thousands of wafers. Therefore, knowing the actual composition of the etch bath is a key element in process control in order to maintain a certain etch rate through replenishment of the consumed acids. The present paper describes a novel approach to quantify nitric acid (HNO(3)), hydrofluoric acid (HF), and hexafluosilicic acid (H(2)SiF(6)) using a high-resolution continuum source graphite furnace absorption spectrometer. The concentrations of Si (via Si atom absorption at the wavelength 251.611 nm, m(0),(Si)=130 pg), of nitrate (via molecular absorption of NO at the wavelength 214.803 nm, [Formula: see text] ), and of total fluoride (via molecular absorption of AlF at the wavelength 227.46 nm, m(0,F)=13 pg) were measured against aqueous standard solutions. The concentrations of H(2)SiF(6) and HNO(3) are directly obtained from the measurements. The HF concentration is calculated from the difference between the total fluoride content, and the amount of fluoride bound as H(2)SiF(6). H(2)SiF(6) and HNO(3) can be determined with a relative uncertainty of less than 5% and recoveries of 97-103% and 96-105%, respectively. With regards to HF, acceptable results in terms of recovery and uncertainty are obtained for HF concentrations that are typical for the photovoltaic industry. The presented procedure has the unique advantage that the concentration of both, acids and metal impurities in etch solutions, can be routinely determined by a single analytical instrument. PMID:22608457

  8. Temperature dependences of saturated vapor pressure and the enthalpy of vaporization of n-pentyl esters of dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Portnova, S. V.; Krasnykh, E. L.; Levanova, S. V.

    2016-05-01

    The saturated vapor pressures and enthalpies of vaporization of n-pentyl esters of linear C2-C6 dicarboxylic acids are determined by the transpiration method in the temperature range of 309.2-361.2 K. The dependences of enthalpies of vaporization on the number of carbon atoms in the molecule and on the retention indices have been determined. The predictive capabilities of the existing calculation schemes for estimation of enthalpy of vaporization of the studied compounds have been analyzed.

  9. Potential heat exchange fluids for use in sulfuric acid vaporizers

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Petersen, G. R.

    1981-01-01

    A series of liquids have been screened as candidate heat exchange fluids for service in thermochemical cycles that involve the vaporization of sulfuric acid. The required chemical and physical criteria of the liquids is described with the results of some preliminary high temperature test data presented.

  10. Study of enhanced low-quality coal oxidative desulphurization and deashing by using HNO3 and microwave pretreatment.

    PubMed

    Ma, Xiangmei; Zhang, Mingxu; Min, Fanfei

    2014-01-01

    In this paper, the effect of urea-hydrogen peroxide (UHP) solution on desulphurization and demineralization of coal with high sulphur and high ash by using HNO3 and microwave pretreatment was investigated. The oxidation process is strongly dependent on irradiation power and time for microwave pretreatment, UHP concentration, leaching time and temperature of the UHP solution. X-ray diffraction and Fourier transform infrared technique have been performed for the raw and treated coals. Compared with the UHP alone, successive treatments with HNO3 and microwave pretreatment resulted in the significant removal of total sulphur and mineral matter from the coal. The proposed experimental method has the meaning of practical guide to the desulphurization and deashing of coal by microwave.

  11. HNO3, N2O5 and CIONO2 Enhancements after the October-November 2003 Solar Proton Events

    NASA Technical Reports Server (NTRS)

    Lopez-Puertas, M.; Funke, B.; Gil-Lopez, S.; Tsidu, G. Mengistu; Fischer, H.; Jackman, C. H.

    2005-01-01

    The large solar storm in October-November 2003 produced enormous amounts of high-energy protons which reached the Earth and penetrated into the middle atmosphere in the polar regions. At this time, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board the Environmental Satellite (ENVISAT) was observing the atmosphere in the 6-68 km altitude range. MIPAS observed significant enhancements of the NO(y) components HNO3, N2O5 and CIONO2 in the Northern polar stratosphere after the intense solar proton events. Two distinct HNO3 enhancements were observed. An instantaneous increase of 1-2 ppbv was observed immediately after the SPEs and is attributed to gas-phase chemistry: NO2 + OH + M yields HNO3 + M, accelerated by SPE-produced excess OH. A very large second increase of 1- 5 ppbv started around 10 November and lasted until the end of December. It is attributed to NO(x) (NO+NO2) produced in the mesosphere during the major SPEs in late October/early November and then transported downwards during November and December, partially converted to N2O5 in the upper stratosphere, which finally formed HNO3 via ion cluster reactions. N2O5 was observed to increase by 0.1-0.4 ppbv 1-3 days after the major SPEs and reached down to 30 km altitude. A second, more pronounced N2O5 enhancement of up to 1.2 ppbv at 40 km appeared about 12-13 days after the major SPEs. With a delay of 1-2 days after the major SPEs CIONO2 increased by up to 0.4 ppbv (40%) at 32 km altitude. NO(y) enhancements in the Southern hemisphere were generally less pronounced.

  12. Balloon-borne radiometer measurement of Northern Hemisphere mid-latitude stratospheric HNO3 profiles spanning 12 years

    NASA Astrophysics Data System (ADS)

    Toohey, M.; Quine, B. M.; Strong, K.; Bernath, P. F.; Boone, C. D.; Jonsson, A. I.; McElroy, C. T.; Walker, K. A.; Wunch, D.

    2007-08-01

    Low-resolution atmospheric thermal emission spectra collected by balloon-borne radiometers over the time span of 1990-2002 are used to retrieve vertical profiles of HNO3, CFC-11 and CFC-12 volume mixing ratios between approximately 10 and 35 km altitude. All of the data analyzed have been collected from launches from a Northern Hemisphere mid-latitude site, during late summer, when stratospheric dynamic variability is at a minimum. The retrieval technique incorporates detailed forward modeling of the instrument and the radiative properties of the atmosphere, and obtains a best fit between modeled and measured spectra through a combination of onion-peeling and global optimization steps. The retrieved HNO3 profiles are consistent over the 12-year period, and are consistent with recent measurements by the Atmospheric Chemistry Experiment-Fourier transform spectrometer satellite instrument. This suggests that, to within the errors of the 1990 measurements, there has been no significant change in the HNO3 summer mid-latitude profile.

  13. Balloon-borne radiometer measurements of Northern Hemisphere mid-latitude stratospheric HNO3 profiles spanning 12 years

    NASA Astrophysics Data System (ADS)

    Toohey, M.; Quine, B. M.; Strong, K.; Bernath, P. F.; Boone, C. D.; Jonsson, A. I.; McElroy, C. T.; Walker, K. A.; Wunch, D.

    2007-12-01

    Low-resolution atmospheric thermal emission spectra collected by balloon-borne radiometers over the time span of 1990-2002 are used to retrieve vertical profiles of HNO3, CFC-11 and CFC-12 volume mixing ratios between approximately 10 and 35 km altitude. All of the data analyzed have been collected from launches from a Northern Hemisphere mid-latitude site, during late summer, when stratospheric dynamic variability is at a minimum. The retrieval technique incorporates detailed forward modeling of the instrument and the radiative properties of the atmosphere, and obtains a best fit between modeled and measured spectra through a combination of onion-peeling and optimization steps. The retrieved HNO3 profiles are consistent over the 12-year period, and are consistent with recent measurements by the Atmospheric Chemistry Experiment-Fourier transform spectrometer satellite instrument. We therefore find no evidence of long-term changes in the HNO3 summer mid-latitude profile, although the uncertainty of our measurements precludes a conclusive trend analysis.

  14. Lifetime Extension of Cirrus Cloud Ice Particles upon Contamination with HCl and HNO3 under conditions of the Upper Troposphere and Lower Stratosphere

    NASA Astrophysics Data System (ADS)

    Rossi, Michel J.; Delval, Christophe

    2016-04-01

    Ice particles in the Upper Troposphere/Lower Stratosphere (UT/LS) are the seat of heterogeneous chemical processes that are important in polar ozone chemistry. Estimated evaporative lifetimes of typical pure ice particles of a few micrometers radius in Cirrus clouds are on the order of a minute or so at 80% relative humidity, too short to allow significant heterogeneous processing. We took this as a motivation to systematically measure absolute rates of evaporation and condensation of H2O in 1 to 2 micrometer thick ice films taken as proxies for small atmospheric ice particles under controlled conditions of HCl and HNO3 trace gas contamination. We have used a multidiagnostic reaction vessel equipped with residual gas mass spectrometry (MS), FTIR absorption spectroscopy in transmission and a quartz crystal microbalance (QCMB) in order to simultaneously observe both the gas and condensed phases under relevant atmospheric conditions. The rates (Rev(H2O)) or fluxes of evaporation (Jev(H2O)) of H2O from thin ice films contaminated by a measured amount of HCl in the range of 10% of a formal monolayer to 20 formal monolayers decreased by factors of between 2 and 50 depending on parameters such as temperature of deposition (Tdep), rate (RHCl) and dose (NHCl) of contaminant doping. Experiments with HCl fell into two categories as far as the decrease of Jev with the average mole fraction of contaminant (χHCl) in the remaining ice slab was concerned: one group where Jev(H2O) decreased gradually after pure ice evaporated, and another group where Jev(H2O) abruptly changes with χHCl after evaporation of excess ice. FTIR spectroscopy revealed an unknown, yet crystalline form of HCl hydrate upon HCl doping that does not correspond to a known crystalline hydrate. Of importance is the observation, that the equilibrium vapor pressure of these contaminated ices correspond to that of pure ice even after evaporation of excess ice at the characteristic rate of pure ice evaporation

  15. Comparison of six denuder methods and a filter pack for the collection of ambient HNO 3(g), HNO 2(g) and SO 2(g) in the 1985 NSMC study

    NASA Astrophysics Data System (ADS)

    Eatough, Norman L.; McGregor, Scott; Lewis, Edwin A.; Eatough, Delbert J.; Huang, Andrew A.; Ellis, Elizabeth C.

    The concentrations of HNO 2(g), HNO 2(g), particle nitrate and particle nitrite have been determined using annular denuders (AD), nylon denuders (ND), short nylon denuders (SD), tungstic acid denuders (TD), cylindrical carbonate denuders (CD), a filter pack (FP), and a denuder difference method (DD) in field tests during the 1985 NSMCS. Concentrations of SO 2(g) and particle sulfate were measured by the annular denuder (AD) and cylindrical carbonate denuder (CD) systems. The results of linear regression comparison of various collection methods for total nitrate, HNO 3(g) and HNO 2(g), and results calculated as the denuder difference between nitrate and nitrite collected on the FP sampler and on the filter pack after the AD are presented. Results for HNO 3(g) and particle nitrate measured by the different sampling systems compared well with the exception of the TD and CD systems. The AD, FP and SD samplers showed the best consistency in results presumably because they operate at higher flow rates and give more sample with correspondingly lower analytical errors. The results obtained for the nitrogenous species studied are also correlated with other atmospheric parameters which might be related to the formation of HNO 3(g) and/or HNO 2(g) in the atmosphere. Concentrations of SO 2(g) measured by the annular denuder (AD) are compared to values determined by flame photometry.

  16. Nitric acid adsorption on ice at environmental temperatures

    NASA Astrophysics Data System (ADS)

    Laird, Susan Kay

    1998-12-01

    Nitric acid has become an important pollutant in areas which depend on snowpack melt for their water supply. The adsorption of HNO3 on the ice surface was investigated at [-]20oC using artificial snow packed into glass columns and exposed to nitric acid vapor in a flow system. It was observed that, given sufficient acid vapor, HNO3 would adsorb in multilayers on the ice, with the bulk of the acid remaining near the input face. With time, molecules from this high-concentration would slowly diffuse down the column, mainly along the ice surface. The surface diffusion coefficient, D, was calculated from both the average linear migration distance, /langle x/rangle, and Fick's First Law to be 3.5×10-7 cm2/sec. The vapor pressure was calculated from Fick's First Law to be 2.3([/pm]0.3)×10-7 torr. Desorption was found to be of zero order and the energy of desorption at [-]20oC was calculated from an Arrhenius-type equation to be 88.8([/pm]0.1) kJ/mol. This means that the HNO3 will tend to stay on the ice surface in a snowpack.

  17. Molecular weight of aquatic fulvic acids by vapor pressure osmometry

    USGS Publications Warehouse

    Aiken, G.R.; Malcolm, R.L.

    1987-01-01

    The molecular weights of aquatic fulvic acids extracted from five rivers were determined by vapor pressure osmometry with water and tetrahydrofuran as solvents. The values obtained ranged from 500 to 950 dallons, indicating that the molecular weights of aquatic fulvic acids are not as great as has been suggested in some other molecular weight studies. The samples were shown to be relatively monodisperse from radii of gyration measurements determined by small angle x-ray scattering. THF affords greater precision and accuracy than H2O in VPO measurements, and was found to be a suitable solvent for the determination of molecular weight of aquatic fulvic acid because it obviates the dissociation problem. An inverse correlation was observed with these samples between the concentration of Ca++ and Mg++ in the river water and the radii of gyration and molecular weights of the corresponding fulvic acid samples. ?? 1987.

  18. Commercial Alloys for Sulfuric Acid Vaporization in Thermochemical Hydrogen Cycles

    SciTech Connect

    Thomas M. Lillo; Karen M. Delezene-Briggs

    2005-10-01

    Most thermochemical cycles being considered for producing hydrogen include a processing stream in which dilute sulfuric acid is concentrated, vaporized and then decomposed over a catalyst. The sulfuric acid vaporizer is exposed to highly aggressive conditions. Liquid sulfuric acid will be present at a concentration of >96 wt% (>90 mol %) H2SO4 and temperatures exceeding 400oC [Brown, et. al, 2003]. The system will also be pressurized, 0.7-3.5 MPa, to keep the sulfuric acid in the liquid state at this temperature and acid concentration. These conditions far exceed those found in the commercial sulfuric acid generation, regeneration and handling industries. Exotic materials, e.g. ceramics, precious metals, clad materials, etc., have been proposed for this application [Wong, et. al., 2005]. However, development time, costs, reliability, safety concerns and/or certification issues plague such solutions and should be considered as relatively long-term, optimum solutions. A more cost-effective (and relatively near-term) solution would be to use commercially-available metallic alloys to demonstrate the cycle and study process variables. However, the corrosion behavior of commercial alloys in sulfuric acid is rarely characterized above the natural boiling point of concentrated sulfuric acid (~250oC at 1 atm). Therefore a screening study was undertaken to evaluate the suitability of various commercial alloys for concentration and vaporization of high-temperature sulfuric acid. Initially alloys were subjected to static corrosion tests in concentrated sulfuric acid (~95-97% H2SO4) at temperatures and exposure times up to 200oC and 480 hours, respectively. Alloys with a corrosion rate of less than 5 mm/year were then subjected to static corrosion tests at a pressure of 1.4 MPa and temperatures up to 375oC. Exposure times were shorter due to safety concerns and ranged from as short as 5 hours up to 144 hours. The materials evaluated included nickel-, iron- and cobalt

  19. Acid Vapor Weathering of Apatite and Implications for Mars

    NASA Technical Reports Server (NTRS)

    Hausrath, E. M.; Golden, D. C.; Morris, R. V.; Ming, D. W.

    2008-01-01

    Phosphorus is an essential nutrient for terrestrial life, and therefore may be important in characterizing habitability on Mars. In addition, phosphate mobility on Mars has been postulated as an indicator of early aqueous activity [1]. Rock surfaces analyzed by the Spirit Mars Exploration Rover indicate elemental concentrations consistent with the loss of a phosphate-containing mineral [2], and the highly altered Paso Robles deposit contains 5% P2O5, modeled as 8-10 % phosphate [3]. Depending on the pH of the solution, phosphate can exist as one of four charge states, which can affect its solubility, reactivity and mobility. Phosphate may therefore prove a useful and interesting tracer of alteration conditions on Mars. Acid vapor weathering has been previously studied as a potentially important process on Mars [4-6], and Paso Robles may have been formed by reaction of volcanic vapors with phosphate-bearing rock [3, 7]. Here we present preliminary results of acid vapor reactions in a Parr vessel [6] using fluorapatite, olivine and glass as single phases and in a mixture.

  20. Kinetic Study of Heterogeneous Reaction of Deliquesced NaCI Particles with Gaseous HNO3 Using Particle-on-Substrate Stagnation Flow Reactor Approach

    SciTech Connect

    Liu, Yong; Cain, Jeremy P.; Wang, Hai; Laskin, Alexander

    2007-10-11

    Heterogeneous reaction kinetics of gaseous nitric acid with deliquesced sodium chloride particles were investigated with a novel Particle-on-Substrate Stagnation Flow Reactor (PS-SFR) approach under conditions, including particle size, relative humidity and reaction time, directly relevant to the atmospheric chemistry of sea salt particles. Particles deposited onto an electron microscopy grid substrate were exposed to the reacting gas at atmospheric pressure and room temperature by impingement via a stagnation flow inside the reactor. The reactor design and choice of flow parameters were guided by computational fluid dynamics results to ensure uniformity of the diffusion flux to all particles undergoing reaction. The chloride depletion in the particles was followed by computer-controlled scanning electron microscopy with energy-dispersive X-ray analysis (CCSEM/EDX). The validity of the current approach was examined first by conducting experiments with median dry particle diameter = 0.82 μm, 80% relative humidity, particle loading densities 4×104 ≤ Ns ≤ 7×106 cm–2 and free stream HNO3 concentrations 2, 7 and 22 ppb. Upon deliquescence the droplet diameter approximately doubles. The apparent, pseudo first-order rate constant determined in these experiments varied with particle loading and HNO3 concentration in a manner consistent with a diffusion-kinetic analysis reported earlier (Laskin, A.; Wang, H.; Robertson, W. H.; Cowin, J. P.; Ezell, M. J.; Finlayson-Pitts, B. J. J. Phys. Chem. A 2006, 110, 10619). The intrinsic, second-order rate constant was obtained as kII = 5.7×10–15 cm3molecule–1s–1 in the limit of zero particle loading and by assuming that the substrate is inert to HNO3. Under this loading condition the experimental, net reaction uptake coefficient was found to be γnet = 0.11 with an uncertainty factor of 3. Additional experiments examined the variations of HNO3 uptake on pure NaCl, a sea salt-like mixture of NaCl and MgCl2 (Mg

  1. Revising the retrieval technique of a long-term stratospheric HNO3 data set: from a constrained matrix inversion to the optimal estimation algorithm

    NASA Astrophysics Data System (ADS)

    Fiorucci, I.; Muscari, G.; de Zafra, R. L.

    2011-07-01

    The Ground-Based Millimeter-wave Spectrometer (GBMS) was designed and built at the State University of New York at Stony Brook in the early 1990s and since then has carried out many measurement campaigns of stratospheric O3, HNO3, CO and N2O at polar and mid-latitudes. Its HNO3 data set shed light on HNO3 annual cycles over the Antarctic continent and contributed to the validation of both generations of the satellite-based JPL Microwave Limb Sounder (MLS). Following the increasing need for long-term data sets of stratospheric constituents, we resolved to establish a long-term GMBS observation site at the Arctic station of Thule (76.5° N, 68.8° W), Greenland, beginning in January 2009, in order to track the long- and short-term interactions between the changing climate and the seasonal processes tied to the ozone depletion phenomenon. Furthermore, we updated the retrieval algorithm adapting the Optimal Estimation (OE) method to GBMS spectral data in order to conform to the standard of the Network for the Detection of Atmospheric Composition Change (NDACC) microwave group, and to provide our retrievals with a set of averaging kernels that allow more straightforward comparisons with other data sets. The new OE algorithm was applied to GBMS HNO3 data sets from 1993 South Pole observations to date, in order to produce HNO3 version 2 (v2) profiles. A sample of results obtained at Antarctic latitudes in fall and winter and at mid-latitudes is shown here. In most conditions, v2 inversions show a sensitivity (i.e., sum of column elements of the averaging kernel matrix) of 100 ± 20 % from 20 to 45 km altitude, with somewhat worse (better) sensitivity in the Antarctic winter lower (upper) stratosphere. The 1σ uncertainty on HNO3 v2 mixing ratio vertical profiles depends on altitude and is estimated at ~15 % or 0.3 ppbv, whichever is larger. Comparisons of v2 with former (v1) GBMS HNO3 vertical profiles, obtained employing the constrained matrix inversion method, show that

  2. Aerosol chamber study of optical constants and N2O5 uptake on supercooled H2SO4/H2O/HNO3 solution droplets at polar stratospheric cloud temperatures.

    PubMed

    Wagner, Robert; Naumann, Karl-Heinz; Mangold, Alexander; Möhler, Ottmar; Saathoff, Harald; Schurath, Ulrich

    2005-09-15

    The mechanism of the formation of supercooled ternary H(2)SO(4)/H(2)O/HNO(3) solution (STS) droplets in the polar winter stratosphere, i.e., the uptake of nitric acid and water onto background sulfate aerosols at T < 195 K, was successfully mimicked during a simulation experiment at the large coolable aerosol chamber AIDA of Forschungszentrum Karlsruhe. Supercooled sulfuric acid droplets, acting as background aerosol, were added to the cooled AIDA vessel at T = 193.6 K, followed by the addition of ozone and nitrogen dioxide. N(2)O(5), the product of the gas phase reaction between O(3) and NO(2), was then hydrolyzed in the liquid phase with an uptake coefficient gamma(N(2)O(5)). From this experiment, a series of FTIR extinction spectra of STS droplets was obtained, covering a broad range of different STS compositions. This infrared spectra sequence was used for a quantitative test of the accuracy of published infrared optical constants for STS aerosols, needed, for example, as input in remote sensing applications. The present findings indicate that the implementation of a mixing rule approach, i.e., calculating the refractive indices of ternary H(2)SO(4)/H(2)O/HNO(3) solution droplets based on accurate reference data sets for the two binary H(2)SO(4)/H(2)O and HNO(3)/H(2)O systems, is justified. Additional model calculations revealed that the uptake coefficient gamma(N(2)O(5)) on STS aerosols strongly decreases with increasing nitrate concentration in the particles, demonstrating that this so-called nitrate effect, already well-established from uptake experiments conducted at room temperature, is also dominant at stratospheric temperatures.

  3. Aerosol chamber study of optical constants and N2O5 uptake on supercooled H2SO4/H2O/HNO3 solution droplets at polar stratospheric cloud temperatures.

    PubMed

    Wagner, Robert; Naumann, Karl-Heinz; Mangold, Alexander; Möhler, Ottmar; Saathoff, Harald; Schurath, Ulrich

    2005-09-15

    The mechanism of the formation of supercooled ternary H(2)SO(4)/H(2)O/HNO(3) solution (STS) droplets in the polar winter stratosphere, i.e., the uptake of nitric acid and water onto background sulfate aerosols at T < 195 K, was successfully mimicked during a simulation experiment at the large coolable aerosol chamber AIDA of Forschungszentrum Karlsruhe. Supercooled sulfuric acid droplets, acting as background aerosol, were added to the cooled AIDA vessel at T = 193.6 K, followed by the addition of ozone and nitrogen dioxide. N(2)O(5), the product of the gas phase reaction between O(3) and NO(2), was then hydrolyzed in the liquid phase with an uptake coefficient gamma(N(2)O(5)). From this experiment, a series of FTIR extinction spectra of STS droplets was obtained, covering a broad range of different STS compositions. This infrared spectra sequence was used for a quantitative test of the accuracy of published infrared optical constants for STS aerosols, needed, for example, as input in remote sensing applications. The present findings indicate that the implementation of a mixing rule approach, i.e., calculating the refractive indices of ternary H(2)SO(4)/H(2)O/HNO(3) solution droplets based on accurate reference data sets for the two binary H(2)SO(4)/H(2)O and HNO(3)/H(2)O systems, is justified. Additional model calculations revealed that the uptake coefficient gamma(N(2)O(5)) on STS aerosols strongly decreases with increasing nitrate concentration in the particles, demonstrating that this so-called nitrate effect, already well-established from uptake experiments conducted at room temperature, is also dominant at stratospheric temperatures. PMID:16834200

  4. Interaction of Ethyl Alcohol Vapor with Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun

    2006-01-01

    We investigated the uptake of ethyl alcohol (ethanol) vapor by sulfuric acid solutions over the range approx.40 to approx.80 wt % H2SO4 and temperatures of 193-273 K. Laboratory studies used a fast flow-tube reactor coupled to an electron-impact ionization mass spectrometer for detection of ethanol and reaction products. The uptake coefficients ((gamma)) were measured and found to vary from 0.019 to 0.072, depending upon the acid composition and temperature. At concentrations greater than approx.70 wt % and in dilute solutions colder than 220 K, the values approached approx.0.07. We also determined the effective solubility constant of ethanol in approx.40 wt % H2SO4 in the temperature range 203-223 K. The potential implications to the budget of ethanol in the global troposphere are briefly discussed.

  5. Evidence That Nitric Acid Increases Relative Humidity in Low-Temperature Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    Gao, R. S.; Popp, P. J.; Fahey, D. W.; Marcy, T. P.; Herman, R. L.; Weinstock, E. M.; Baumgardner, D. G.; Garrett, T. J.; Rosenlof, K. H.; Thompson, T. L.

    2004-01-01

    In situ measurements of the relative humidity with respect to ice (RH(sub(i)) and of nitric acid (HNO3) were made in both natural and contrail cirrus clouds in the upper troposphere. At temperatures lower than 202 kelvin, RH(sub i) values show a sharp increase to average values of over 130% in both cloud types. These enhanced RH(sub i) values are attributed to the presence of a new class of NHO3- containing ice particles (Delta-ice). We propose that surface HNO3 molecules prevent the ice/vapor system from reaching equilibrium by a mechanism similar to that of freezing point depression by antifreeze proteins. Delta-ice represents a new link between global climate and natural and anthropogenic nitrogen oxide emissions. Including Delta-ice in climate models will alter simulated cirrus properties and the distribution of upper tropospheric water vapor.

  6. Kinetics of electron attachment to OH and HNO3 and mutual neutralization of Ar+ with NO2- and NO3- at 300 and 500 K

    NASA Astrophysics Data System (ADS)

    Shuman, Nicholas S.; Miller, Thomas M.; Viggiano, A. A.

    2012-03-01

    The electron attachment rate constant to nitric acid (HNO3) has been measured in a flowing afterglow-Langmuir probe (FALP) apparatus at 300 and 500 K using three independent methods: the traditional FALP technique of monitoring electron depletion, "one-gas" VENDAMS (variable electron and neutral density attachment mass spectrometry), and "two-gas" VENDAMS. The three measurements are in agreement with a 300 K weighted average of 1.4 ± 0.3 × 10-7 cm3 s-1, 2 to 10 times higher than previously reported values. Attachment is primarily dissociative yielding NO2- as previously reported, but for the first time a small endothermic channel to produce OH- was also observed at 500 K. From the one-gas VENDAMS data, associative attachment to the OH produced in the primary attachment was found to occur with an effective two body rate constant of 1.2 ± _{0.7}^3 × 10-11 cm3 s-1 at 300 K, the first reported rate constant for this radical species. Finally, ion-ion neutralization rate constants of NO2- and NO3- with Ar+ were determined to be 5.2 ± _{2.5}^{1.5} × 10-8 and 4.5 ± 2.5 × 10-8 cm3 s-1 at 300 K, respectively.

  7. A theoretical investigation of gaseous absorption by water droplets from SO2-HNO3-NH3-CO2-HCl mixtures

    NASA Technical Reports Server (NTRS)

    Adewuyi, Y. G.; Carmichael, G. R.

    1982-01-01

    A physical-chemical model is developed and used to investigate gaseous absorption by water droplets from trace gas mixtures. The model is an extension of that of Carmichael and Peters (1979) and includes the simultaneous absorption of SO2, NH3, HNO3, CO2, and HCl. Gas phase depletion is also considered. Presented results demonstrate that the absorption behavior of raindrops is strongly dependent on drop size, fall distance, trace gas concentrations, and the chemical and physical properties of the constituents of the mixture. In addition, when gas phase depletion is considered, the absorption rates and equilibrium values are also dependent on the precipitation rate itself. Also, the trace constituents liquid phase concentrations may be a factor of six or more lower when gas depletion is considered then when the depletion is ignored. However, the hydrogen ion concentration may be insensitive to the gas phase depletion.

  8. Kinetics of the Reactions of F((sup 2)P) and Cl((sup 2)P) with HNO3

    NASA Technical Reports Server (NTRS)

    Wine, P. H.; Wells, J. R.; Nicovich, J. M.

    1997-01-01

    The kinetics of the reactions of HNO3 with fluorine (k(sub 1)) and Chlorine (k(sub 2)) atoms have been studied by using a time-resolved long-path laser absorption technique to monitor the appearance of product NO3 radicals following 351-nm pulsed laser photolysis of X2/HNO3/He mixtures (X = F,Cl). Absolute rate coefficients for the F((sup 2)P) + HNO reaction have been determined over the temperature range 260-373 K. Between 260 and 320 K, the data are adequately represented by the Arrhenius expression k(sub 1)(T) = (6.0 +/- 2.6) x 10(exp -12) exp[(40 +/- 120)/T]cu cm/(molecule.s). Between 335 and 373 K, the rate coefficient is found to be (2.0 +/- 0.3) x 10(exp -11)cu cm/(molecule.s) independent of temperature. The observed temperature dependence suggests that reaction proceeds via competing direct abstraction and complex pathways. No NO3 production was observed in the experiments with X equals Cl, thus establishing that k(sub 2)(298 K) is less than 2 x 10(exp -16) cu cm/(molecule.s). The Cl((sup 2)P) + HNO reaction was also investigated by using a pulsed laser photolysis-resonance fluorescence technique to monitor the decay of Cl((sup 2)P). Upper limit values for k(sub 2) obtained from these experiments, in units of 10(exp -16)cu cm/(molecule.s), are 13 at 298 K and 10 at 400 K.

  9. Balloon profiles of stratospheric NO2 and HNO3 for testing the heterogeneous hydrolysis of N2O5 on sulfate aerosols

    NASA Technical Reports Server (NTRS)

    Webster, C. R.; May, R. D.; Allen, M.; Jaegle, L.; Mccormick, M. P.

    1994-01-01

    Simultaneous in situ measurements of stratospheric NO2, HNO3, HCl, and CH4 from 34 to 24 km were made in August 1992 from Palestine, Texas, using the Balloon-borne Laser In-Situ Sensor (BLISS) tunable diode laser spectrometer. Although the measurements of NO2, HNO3, and NO2/HNO3 agree well with gas-phase model calculations near 34 km where Stratospheric Aerosol and Gas Experiment (SAGE) 2 data show little sulfate aerosol, this is not true at the lower altitudes where SAGE 2 shows high aerosol loadings. At 24 km the BLISS NO2 and HNO3 measurements are 70% lower and 50% higher, respectively, than the gas phase model predictions, with a measured NO2/HNO3 ratio 5 times smaller. When the heterogeneous hydrolysis of N2O5 and ClONO2 on sulfate aerosol of surface area densities matching the SAGE 2 measurements is added to the model, good agreement with the BLISS measurements is found over the whole altitude range.

  10. High-sensitivity matrix-assisted laser desorption/ionization Fourier transform mass spectrometry analyses of small carbohydrates and amino acids using oxidized carbon nanotubes prepared by chemical vapor deposition as matrix.

    PubMed

    Wang, Cui-hong; Li, Jian; Yao, Sheng-jun; Guo, Yin-long; Xia, Xing-hua

    2007-12-01

    In matrix-assisted laser desorption/ionization (MALDI) Fourier transform mass spectrometry (FTMS) analyses of small oligosaccharides and amino acids, high sensitivities for oligosaccharides (10 fmol) were obtained by introducing oxidized carbon nanotubes (CNTs) with short and open-end structure as valuable matrix. The CNTs were deposited in porous anodic alumina (PAA) templates by chemical vapor deposition. Transmission electron microscopy (TEM) images show that those CNTs include low levels of amorphous carbon. Thus, the background interference signals generally caused by amorphous carbon powder in CNTs can be reduced effectively. Experiments also confirmed that the FTMS signal intensity of CNTs prepared in PAA template is much lower than that of commercial multi-wall carbon nanotubes (MCNTs). Moreover, the purified process for CNTs with mixed acid (H2SO4 and HNO3) also contributed to the minimization of background. Intense signals corresponding to alkali cation adduct of neutral carbohydrates and amino acids have been acquired. In addition, reliable quantitative analyses for urine and corn root were also achieved successfully. The present work will open a new way to the application of oxidized CNTs as an effective matrix in MALDI MS research.

  11. Observations and Modeling of Composition of Upper Troposphere/Lower Stratosphere (UTILS): Isentropic Mixing Events and Morphology of HNO3 as Observed by HIRDLS and Comparison with Results from Global Modeling Initiative

    NASA Technical Reports Server (NTRS)

    Rodriquez, J. M.; Douglass, A.R.; Yoshida, Y.; Strahan, S.; Duncan, B.; Olsen, M.; Gille, J.; Yudin, V.; Nardi, B.

    2008-01-01

    isentropic exchange of air masses between the tropical upper troposphere and mid-latitude lowermost stratosphere (the so-called "middle world") is an important pathway for stratospheric-tropospheric exchange. A seasonal, global view of this process has been difficult to obtain, in part due to the lack of the vertical resolution in satellite observations needed to capture the laminar character of these events. Ozone observations at a resolution of about 1 km from the High Resolution Dynamic Limb Sounder (HIRDLS) on NASA's Aura satellite show instances of these intrusions. Such intrusions should also be observable in HN03 observations; however, the abundances of nitric acid could be additionally controlled by chemical processes or incorporation and removal into ice clouds. We present a systematic examination of the HIRDLS data on O3 and HNO3 to determine the seasonal and spatial characteristics of the distribution of isentropic intrusions. At the same time, we compare the observed distributions with those calculated by the Global Modeling Initiative combined tropospheric-stratospheric model, which has a vertical resolution of about I km. This Chemical Transport Model (CTM) is driven by meteorological fields obtained from the GEOS-4 system of NASA/Goddard Global Modeling and Assimilation Office (GMAO), for the Aura time period, at a vertical resolution of about 1 km. Such comparison brings out the successes and limitations of the model in representing isentropic stratospheric-tropospheric exchange, and the different processes controlling HNO3 in the UTAS.

  12. Measurements of NO2, SO2, NH3, HNO3 and O3 in West African urban environments

    NASA Astrophysics Data System (ADS)

    Adon, Marcellin; Yoboué, Véronique; Galy-Lacaux, Corinne; Liousse, Catherine; Diop, Babakar; Doumbia, El Hadji Thierno; Gardrat, Eric; Ndiaye, Seydi Ababacar; Jarnot, Christian

    2016-06-01

    In this paper, we present the measurements of atmospheric gas concentrations of NO2, SO2, NH3, HNO3, and O3 performed at two traffic sites in the context of the POLCA (Pollution of African Capitals) program. These gases were measured using a passive sampling technique from Jan. 2008 to Dec. 2009 at Dakar and from Jun. 2008 to Dec. 2009 at Bamako. In addition, during these periods there were two intensive measurement campaigns (from 19 Jan. to 2 Feb. 2009 at Bamako and from 30 Nov. to 13 Dec. 2009 at Dakar) where real-time active analysers were used to measure NO2 and SO2. Results show that Dakar has a pollution level for NO2 and SO2 higher than that of Bamako, whereas it is lower for NH3 concentrations. Monthly values of NO2 range between 21.1 and 43.5 ppb in Dakar with an annual mean concentration of 31.7 ppb (59.6 μg/m3). NO2 values in Bamako are 9.4-22.6 ppb with a mean of 16.2 ppb. At Dakar, the mean annual NO2 limit value (21.3 ppb or 40 μg/m3) recommended by the World Health Organization (WHO) is widely exceeded. The mean annual concentration of SO2 is 15.9 ppb in Dakar and 3.6 ppb in Bamako. These differences may be explained by different sources of traffic between Bamako (with mainly gasoline vehicles) and Dakar (with mainly diesel vehicles). The annual mean NH3 concentration is about two times higher in Bamako (46.7 ppb) than in Dakar (21.1 ppb). In addition to other possible sources, we assume that the ammonia from domestic fires and uncontrolled garbage incineration may have more influence at Bamako than at Dakar. The mean annual concentrations of HNO3 and O3 are 1.3 ppb and 7.7 ppb in Dakar and 0.6 ppb and 5.1 ppb in Bamako, respectively. Seasonal variation in measured gas concentrations are low in Bamako and more pronounced in Dakar, except for HNO3 and NH3. At Dakar, NO2 and SO2 daily mean concentrations are higher during the weekdays than on weekends, when urban activities are reduced, whereas at Bamako, no significant difference was observed

  13. Intercomparison of Clean Air Status and Trends Network (CASTNET) NO3 - and HNO3 Measurements with Data from Other Monitoring Programs

    EPA Science Inventory

    The EPA Clean Air Status and Trends Network (CASTNET) utilizes an open face filter pack system to measure concentrations of atmospheric sulfur and nitrogen species. The purpose of this study was to estimate the uncertainty in seasonal and annual concentrations of HNO3, NO3 - , ...

  14. Measurements of HNO3 and N2O5 using Ion drift - Chemical Ionization Mass Spectrometry during the MCMA - 2006 Campaign

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Zhang, R.; Fortner, E. C.; Molina, L.; Aiken, A. C.; Jimenez, J. L.; Gäggeler, K.; Dommen, J.; Dusanter, S.; Stevens, P. S.; Tie, X.

    2008-03-01

    An ion drift - chemical ionization mass spectrometry (ID-CIMS) was deployed in Mexico City between 5 and 31 March to measure HNO3 and N2O5 during the 2006 Mexico City Metropolitan Area (MCMA) field campaign. The observation site, T0, was located at the Instituto Mexicano del Petróleo at the center of the Mexico City Basin with major emissions of pollutants from both domestic and industrial sources. Diurnally, HNO3 was less than 200 parts per trillion (ppt) during the night and in the early morning, increased steadily from around 09:00 a.m. central standard time (CST), reached a peak value of 0.5 to 3 parts per billion (ppb) in the early afternoon, and declined sharply to less than half of the peak value near 05:00 p.m. CST. An inter-comparison between the ID-CIMS and an ion chromatograph/mass spectrometer (ICMS) showed a good correlation in the HNO3 measurements (R2=0.75). The HNO3 mixing ratio was found to anti-correlate with aerosol nitrate, suggesting that the gaseous HNO3 concentration was controlled by the gas-particle partitioning process. During most times of the MCMA 2006 field campaign, N2O5 was found to be under the detection limit (about 20 ppt for a 10 s integration time) of the ID-CIMS, because of high NO mixing ratio (>100 ppb) during the night. With one exception on 26 March 2006, about 40 ppt N2O5 was observed during the late afternoon and early evening hours under a cloudy condition, before NO built up at the surface site. The results revealed that during the 2006 MCMA field campaign HNO3 was primarily produced by the reaction of OH with NO2 and regulated by gas/particle partitioning, and HNO3 production from N2O5 hydrolysis during the nighttime was small because of high NO and low O3 concentrations near the surface.

  15. Direct bonding for dissimilar metals assisted by carboxylic acid vapor

    NASA Astrophysics Data System (ADS)

    Song, Jenn-Ming; Huang, Shang-Kun; Akaike, Masatake; Suga, Tadatomo

    2015-03-01

    This study developed a low-temperature low-vacuum direct bonding process for dissimilar metals via surface modification with formic acid vapor. Robust Cu/Ag and Cu/Zn bonding with a shear strength higher than 25 MPa can be achieved by thermal compression at 275 and 300 °C, respectively. CuZn5 and Cu5Zn8 formed at the interface of Cu/Zn joints, while no distinct interdiffusion layers appeared at the Cu/Ag interface. At elevated temperatures, the shear strength of Cu/Zn joints decreased significantly and turned to be weaker than Cu/Ag at 250 °C due to the softening of Zn. All the joints performed well subjected to thermal cycling up to 1000 times. However, compared with Cu/Ag joints with stable mechanical performance suffering aging at 250 °C, the shear strength of Cu/Zn degraded drastically up to 200 h, and after that it remained almost constant, which can be ascribed to the competitive growth between CuZn5 and Cu5Zn8, resulting in collapse and oxidation of CuZn5.

  16. Controlling surface roughness in vapor-deposited poly(amic acid) films by solvent-vapor exposure.

    PubMed

    Anthamatten, Mitchell; Letts, Stephan A; Cook, Robert C

    2004-07-20

    A series of vapor-deposited poly(amic acid) (PAA) films were exposed to dimethyl sulfoxide (DMSO) vapors to investigate sorption kinetics and surface smoothing phenomena. Gravimetric sorption and secondary-ion mass spectrometry (SIMS) results are both consistent with frontal (case II) diffusion. These experiments suggest that the solvent front is defined by a sharp interface that delineates the swollen material from the unswollen material. Solvent-vapor smoothing was studied by first depositing PAA onto rough aluminum surfaces, and then, during solvent-vapor exposure, the surface topology was continuously monitored using a light interference microscope. The resulting time-dependent power spectra indicate that high-frequency defects smooth faster than low-frequency defects. This frequency dependence was further investigated by depositing PAA onto a series of sinusoidal surfaces and exposing them to solvent vapor inside a flow channel. The sinusoidal amplitudes decay exponentially with time, with decay constants that are proportional to the surface frequency. To explain the physics of surface smoothing, a two-parameter model is presented and agrees qualitatively with experimental data.

  17. Identification of the HNO3 3 nu(sub 9) - nu(sub 9) band Q branch in stratospheric solar occultation spectra

    NASA Technical Reports Server (NTRS)

    Perrin, A.; Flaud, J.-M.; Camy-Peyret, C.; Goldman, A.; Rinsland, C. P.; Gunson, M. R.

    1994-01-01

    The spectroscopic identification for the HNO3 3 nu(sub 9) - nu(sub 9) band Q branch at 830.4/cm is reported based on 0.01/cm resolution solar occultation spectra of the lower stratosphere recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer and a recent analysis of this band. Least-squares fits to 0.0025/cm resolution laboratory spectra in the Q branch region indicate an integrated intensity of 0.529 x 10(exp -18)/cm/mol/sq cm at 296 K for this weak band. Stratospheric HNO3 retrievals derived from the ATMOS data are consistent with this value within its estimated uncertainty of about +/- 30%. A set of spectroscopic line parameters suitable for atmospheric studies has been generated.

  18. The role of ion-molecule reactions in the conversion of N2O5 to HNO3 in the stratosphere

    NASA Astrophysics Data System (ADS)

    Bohringer, H.; Fahey, D. W.; Fehsenfeld, F. C.; Ferguson, E. E.

    1983-02-01

    The role of several ion-molecule reactions in the conversion of N2O5 to HNO3 was investigated. In the proposed conversion, an N2O5 molecule would react with an H2O molecule clustered to an inert ion to produce two HNO3 molecules. Subsequent clustering of an H2O molecule to the inert ion would make the reaction catalytic. If such an ion-catalyzed conversion of N2O5 to HNO3 occurs, it would probably play a role in the stratospheric chemistry at high latitudes in winter. Reaction rate constant measurements made in a flowing afterglow apparatus flor hydrated H3O(+), H(+)(CH3CN)m(m equals 1,2,3), and several negative ions reacting with N2O5 are presented. Slow rate constants were found for these ions for hydration levels that are predominant in the stratosphere. With the known stratospheric ion density, these slow rate constants preclude significant N2O5 conversion by ion-molecule reactions.

  19. Vapor pressures of substituted polycarboxylic acids are much lower than previously reported

    NASA Astrophysics Data System (ADS)

    Huisman, A. J.; Krieger, U. K.; Zuend, A.; Marcolli, C.; Peter, T.

    2013-07-01

    The partitioning of compounds between the aerosol and gas phase is a primary focus in the study of the formation and fate of secondary organic aerosol. We present measurements of the vapor pressure of 2-methylmalonic (isosuccinic) acid, 2-hydroxymalonic (tartronic) acid, 2-methylglutaric acid, 3-hydroxy-3-carboxy-glutaric (citric) acid and DL-2,3-dihydroxysuccinic (DL-tartaric) acid, which were obtained from the evaporation rate of supersaturated liquid particles levitated in an electrodynamic balance. Our measurements indicate that the pure component liquid vapor pressures at 298.15 K for tartronic, citric and tartaric acids are much lower than the same quantity that was derived from solid state measurements in the only other room temperature measurement of these materials (made by Booth et al., 2010). This strongly suggests that empirical correction terms in a recent vapor pressure estimation model to account for the inexplicably high vapor pressures of these and similar compounds should be revisited, and that due caution should be used when the estimated vapor pressures of these and similar compounds are used as inputs for other studies.

  20. What Is the Boiling Point and Heat of Vaporization of Sulfuric Acid?

    ERIC Educational Resources Information Center

    Myers, R. Thomas

    1983-01-01

    Discusses the values presented in various handbooks for the boiling point and heat of vaporization of sulfuric acid, noting discrepencies. Analyzes various approaches to data presentation, discussing the data on sulfuric acid in light of the Trouton constant. Points out the need for a more critical use of tables. (JM)

  1. Robust antifogging antireflective coatings on polymer substrates by hydrochloric acid vapor treatment.

    PubMed

    Li, Tong; He, Junhui; Yao, Lin; Geng, Zhi

    2015-04-15

    Antireflective coatings on polymer substrates have received significant attention for their potential applications. In this paper, robust microporous antifogging antireflective coatings on polymer substrates were prepared from acid-catalyzed silica sol followed by hydrochloric acid vapor solidification at mild temperature below glass transition temperatures of common polymers. The coatings passed 3H pencil hardness test, sand flow test and water-drop test. They had excellent antireflective and antifogging properties. The maximum transmittance of coatings on PMMA substrates reached 100.0% (the maximum transmittance wavelength could be regulated) and average transmittance reached 99.0% in 400-800 nm. The advantage and mechanism of hydrochloric acid vapor solidification and mechanical strength enhancement of coatings are discussed in contrast to ammonia vapor treatment and air vapor treatment. The hydrochloric acid vapor treatment results in a dense integrated microporous film structure. Optical properties were characterized by a UV-Vis spectrophotometer. Surface wettability was studied by a contact angle/interface system. Surface morphologies and structures of coatings were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atom force microscopy (AFM).

  2. Dry deposition of nitrogen compounds (NO2, HNO3, NH3), sulfur dioxide and ozone in West and Central African ecosystems using the inferential method

    NASA Astrophysics Data System (ADS)

    Adon, M.; Galy-Lacaux, C.; Yoboue, V.; Delon, C.; Solmon, F.; Kaptue Tchuente, A. T.

    2013-05-01

    This work is part of the IDAF program (IGAC-DEBITS-AFRICA) and is based on the long term monitoring of gas concentrations (1998-2007) established on seven remote sites representative of major African ecosystems. Dry deposition fluxes were estimated by the inferential method using on one hand surface measurements of gas concentrations (NO2, HNO3, NH3, SO2, and O3) and on the other hand simulated dry deposition velocities (Vd). Vd were calculated using the big-leaf model of Zhang et al. (2003b). In the model of deposition, surface and meteorological conditions specific to IDAF sites have been adapted in order to simulate Vd representative of major African ecosystems. The monthly, seasonal and annual mean variations of gaseous dry deposition fluxes (NO2, HNO3, NH3, O3, and SO2) are analyzed. Along the latitudinal transect of ecosystems, the annual mean dry deposition fluxes of nitrogen compounds range from 0.4 ± 0.0 to 0.8 ± 0.2 kg N ha-1 yr-1 for NO2, from 0.7 ± 0.1 to 1.0 ± 0.3 kg N ha-1 yr-1 for HNO3, and from 2.3 ± 0.8 to 10.5 ± 5.0 kg N ha-1 yr-1 for NH3 over the study period (1998-2007). The total nitrogen dry deposition flux (NO2+HNO3+NH3) is more important in forests (11.2-11.8 kg N ha-1 yr-1) than in wet and dry savannas (3.4-5.3 kg N ha-1 yr-1). NH3 dominated nitrogen dry deposition, representing 67-80% of the total. The annual mean dry deposition fluxes of ozone range between 11.3 ± 4.7 and 17.5 ± 3.0 kg ha-1 yr-1 in dry savannas, 17.5 ± 3.0 and 19.2 ± 2.9 kg ha-1 yr-1 in wet savannas, and 10.6 ± 2.0 and 13.2 ± 3.6 kg ha-1 yr-1 in forests. Lowest O3 dry deposition fluxes in forests are correlated to low measured O3 concentrations, lower of a factor of 2-3, compared to others ecosystems. Along the ecosystem transect, annual mean of SO2 dry deposition fluxes present low values and a small variability (0.5 to 1 kg S ha-1 yr-1). No specific trend in the interannual variability of these gaseous dry deposition fluxes is observed over the study period.

  3. Dry deposition of nitrogen compounds (NO2, HNO3, NH3), sulfur dioxide and ozone in west and central African ecosystems using the inferential method

    NASA Astrophysics Data System (ADS)

    Adon, M.; Galy-Lacaux, C.; Delon, C.; Yoboue, V.; Solmon, F.; Kaptue Tchuente, A. T.

    2013-11-01

    This work is part of the IDAF program (IGAC-DEBITS-AFRICA) and is based on the long-term monitoring of gas concentrations (1998-2007) established at seven remote sites representative of major African ecosystems. Dry deposition fluxes were estimated by the inferential method using on the one hand surface measurements of gas concentrations (NO2, HNO3, NH3, SO2 and O3) and on the other hand modeled exchange rates. Dry deposition velocities (Vd) were calculated using the big-leaf model of Zhang et al. (2003b). The bidirectional approach is used for NH3 surface-atmosphere exchange (Zhang et al., 2010). Surface and meteorological conditions specific to IDAF sites have been used in the models of deposition. The seasonal and annual mean variations of gaseous dry deposition fluxes (NO2, HNO3, NH3, O3 and SO2) are analyzed. Along the latitudinal transect of ecosystems, the annual mean dry deposition fluxes of nitrogen compounds range from -0.4 to -0.8 kg N ha-1 yr-1 for NO2, from -0.7 to -1.0 kg N ha-1 yr-1 for HNO3 and from -0.7 to -8.3 kg N ha-1 yr-1 for NH3 over the study period (1998-2007). The total nitrogen dry deposition flux (NO2+HNO3+NH3) is more important in forests (-10 kg N ha-1 yr-1) than in wet and dry savannas (-1.6 to -3.9 kg N ha-1 yr-1). The annual mean dry deposition fluxes of ozone range between -11 and -19 kg ha-1 yr-1 in dry and wet savannas, and -11 and -13 kg ha-1 yr-1 in forests. Lowest O3 dry deposition fluxes in forests are correlated to low measured O3 concentrations, lower by a factor of 2-3, compared to other ecosystems. Along the ecosystem transect, the annual mean of SO2 dry deposition fluxes presents low values and a small variability (-0.5 to -1 kg S ha-1 yr-1). No specific trend in the interannual variability of these gaseous dry deposition fluxes is observed over the study period.

  4. Structure-property relationships in halogenbenzoic acids: Thermodynamics of sublimation, fusion, vaporization and solubility.

    PubMed

    Zherikova, Kseniya V; Svetlov, Aleksey A; Kuratieva, Natalia V; Verevkin, Sergey P

    2016-10-01

    Temperature dependences of vapor pressures for 2-, 3-, and 4-bromobenzoic acid, as well as for five isomeric bromo-methylbenzoic acids were studied by the transpiration method. Melting temperatures and enthalpies of fusion for all isomeric bromo-methylbenzoic acids and 4-bromobenzoic acid were measured with a DSC. The molar enthalpies of sublimation and vaporization were derived. These data together with results available in the literature were collected and checked for internal consistency using a group-additivity procedure and results from X-ray structural diffraction studies. Specific (hydrogen bonding) interactions in the liquid and in the crystal phase of halogenbenzoic acids were quantified based on experimental values of vaporization and sublimation enthalpies. Structure-property correlations of solubilities of halogenobenzoic acids with sublimation pressures and sublimation enthalpies were developed and solubilities of bromo-benzoic acids were estimated. These new results resolve much of the ambiguity in the available thermochemical and solubility data on bromobenzoic acids. The approach based on structure property correlations can be applied for the assessment of water solubility of sparingly soluble drugs. PMID:27424058

  5. Steering the efficiency of carbon nanotube-silicon photovoltaic cells by acid vapor exposure: a real-time spectroscopic tracking.

    PubMed

    Pintossi, C; Pagliara, S; Drera, G; De Nicola, F; Castrucci, P; De Crescenzi, M; Crivellari, M; Boscardin, M; Sangaletti, L

    2015-05-13

    Hybrid carbon nanotube-silicon (CNT-Si) junctions have been investigated by angle resolved photoemission spectroscopy (AR-XPS) with the aim to clarify the effects of a nonstoichiometric silicon oxide buried interface on the overall cell efficiency. A complex silicon oxide interface has been clearly identified and its origin and role in the heterojunction have been probed by exposing the cells to hydrofluoric (HF) and nitric (HNO3) acid. Real-time monitoring of the cell efficiencies during the steps following acid exposure (up to 1 week after etching) revealed a correlation between the thickness and chemical state of the oxide layer and the cell efficiencies. By matching the AR-XPS and Raman spectroscopy with the electrical response data it has been possible to discriminate the effects on the cell efficiency of the buried SiO(x) interface from those related to CNT acid doping. The overall cell behavior recorded for different thicknesses of the SiO(x) interface indicates that the buried oxide layer is likely acting as a passivating/inversion layer in a metal-insulator-semiconductor junction.

  6. Modulation of size and viscosity of Ni/Zn ferrites: Effect of doping with βCD and chemical treatment with HNO3 and NaOH

    NASA Astrophysics Data System (ADS)

    Corrêa, Jéssyca M. L.; Abrishamkar, Afshin; Da Silva, Jeferson G.; Pereira, Juliano Rocha; de Oliveira, Fernando C.; Denadai, Ângelo M. L.

    2015-11-01

    In this work, we have studied the rheological properties of nickel-zinc and nickel-zinc-β-cyclodextrin (Fe-Ni/Zn and Fe-Ni/Zn/βCD) ferrite suspensions as a function of temperature, solids content, shear rate and NaOH/HNO3 concentration. The goal was to investigate the conditions where the particle size and viscosity are both lower. In both suspensions, temperature had insignificant impact on viscosity, suggesting no destructive effect on the particles. The Fe-Ni/Zn/βCD suspension exhibited lower viscosity, Newtonian profile and lower dependence of viscosity upon the solids content in comparison with Fe-Ni/Zn, which was pseudoplastic and thixotropic. These differences were ascribed to the lower particle size caused by incorporation of βCD. Considering both ferrites, HNO3 was more efficient in reducing the particles size and viscosity than NaOH, which affected only the Fe-Ni/Zn. This behavior was rationalized in terms of chemical equilibrium of FeOOH at the surface of particles, which was supported by structural characterization as well as elementary analysis.

  7. Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS 1A) Earth limb spectral measurements, calibration, and atmospheric O3, HNO3, CFC-12, and CFC-11 profile retrieval

    NASA Astrophysics Data System (ADS)

    Bingham, G. E.; Zhou, D. K.; Bartschi, B. Y.; Anderson, G. P.; Smith, D. R.; Chetwynd, J. H.; Nadile, R. M.

    1997-02-01

    During the Space Transportation System 39 (STS 39) flight of April 28 to May 6, 1991, the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS 1A) measured spectral and spatial ("Earth limb scan") distributions of the atmospheric infrared (IR) emissions using a Michelson interferometer. The IR spectral radiant emissions from the greenhouse gases were collected at a shuttle altitude of 260 km in the 9-13 μm atmosphere infrared window. Before and after the flight, the response of CIRRIS 1A to the IR spectral emission sources was calibrated using absolute and spectral source types. The Fast Atmospheric Signature Code 3, which used the HITRAN92 database and predetermined temperature-pressure profiles from the National Meteorological Center, was used in an onion-peeling routine to retrieve gas concentrations from absolutely calibrated spectral data (moderate resolution ˜1.0 cm-1). Vertical profiles of O3, HNO3, CFC-12, and CFC-11 are presented. An error analysis is presented to show the quality of the measured spectral data and the accuracy of these retrieval results. The concentrations of CFC-11 (3.0×10-4 ppmv) and CFC-12 (4.9×10-4 ppmv) in the tropopause region are consistent with a global flux increment rate of about 5% yr-1. The observed concentrations of HNO3 are consistent with previous reports for a relatively clean stratosphere.

  8. The use of NO y , H2O2, and HNO3 as indicators for ozone-NO x -hydrocarbon sensitivity in urban locations

    NASA Astrophysics Data System (ADS)

    Sillman, Sanford

    1995-07-01

    Correlations are presented between model predictions for O3-NOx-hydrocarbon sensitivity and afternoon concentrations of four "indicator species": NOy, O3/(NOy-NOx), HCHO/NOy, and H2O2/HNO3. The indicator species correlations are based on a series of photochemical simulations with varying rates of anthropogenic and biogenic emissions and meteorology. Hydrocarbon-sensitive chemistry in models is shown to be linked to afternoon NOy > 20 ppb, O3/(NOy - NOx) < 7, HCHO/NOy < 0.28, and H2O2/HNO3 < 0.4. Lower NOy and higher ratios correspond with NOx-sensitive ozone. The correlation between NOx-hydrocarbon sensitivity and indicator species remains, even when model emission rates and hydrocarbon/NOx ratios are changed by a factor of 2. Methods are developed for evaluating the goodness of fit between model NOx-hydrocarbon sensitivity and indicator values. Ozone chemistry is also analyzed in terms of fundamental properties of odd hydrogen, and theoretical criteria for the transition between NOx- and hydrocarbon-sensitive regimes are derived. A theoretical correlation between O3 and H2O2 + NOy - NOx is developed as a way to extend rural O3-NOy correlations into urban locations. Measured indicator values during pollution events in Los Angeles, Atlanta, and rural Virginia are used to illustrate the range of observed values under different environmental conditions.

  9. LIMS Instrument Package (LIP) balloon experiment: Nimbus 7 satellite correlative temperature, ozone, water vapor, and nitric acid measurements

    NASA Technical Reports Server (NTRS)

    Lee, R. B., III; Gandrud, B. W.; Robbins, D. E.; Rossi, L. C.; Swann, N. R. W.

    1982-01-01

    The Limb Infrared Monitor of the Stratosphere (LIMS) LIP balloon experiment was used to obtain correlative temperature, ozone, water vapor, and nitric acid data at altitudes between 10 and 36 kilometers. The performance of the LIMS sensor flown on the Nimbus 7 Satellite was assessed. The LIP consists of the modified electrochemical concentration cell ozonesonde, the ultraviolet absorption photometric of ozone, the water vapor infrared radiometer sonde, the chemical absorption filter instrument for nitric acid vapor, and the infrared radiometer for nitric acid vapor. The limb instrument package (LIP), its correlative sensors, and the resulting data obtained from an engineering and four correlative flights are described.

  10. Measurement of partial vapor pressure of ammonia over acid ammonium sulfate solutions by an integral method

    NASA Astrophysics Data System (ADS)

    Koutrakis, P.; Aurian-BlǎJeni, B.

    1993-02-01

    We present a simple, integral, passive method for measuring partial vapor pressure. Integral methods are useful tools when dealing with very low concentrations because collection over extended periods increases the analytical sensitivity. Passive methods have the advantage of not introducing constraints external to the system. The principle of the method used here is to selectively react the substance in the atmosphere over a solution with an immobilized coating on an appropriate support. The reaction product is not volatile, but is soluble and can be extracted in an appropriate solvent and analyzed. The method has been applied to measuring the vapor pressure of ammonia over aqueous solutions. The vapor pressure over ammonium sulfate solutions depends on the acidity of the solutions as well as on the salt concentration. The dependence can be explained with a simple model. Furthermore, using the same model, we calculated the ammonia vapor pressure above different ammonium sulfate/sulfuric acid aqueous solutions as a function of sulfate molarity and percentage of sulfuric acid. The results from the calculations suggest that for ambient ammonia concentrations less than 10 ppb, acid sulfate aerosols are not completely neutralized.

  11. Measurement of HONO, HNCO, and Other Inorganic Acids by Negative-ion Proton-Transfer Chemical-Ionization Mass Spectrometry (NI-PT-CIMS):Application to Biomass Burning Emissions.

    SciTech Connect

    Roberts, James M.; Veres, Patrick; Warneke, Carsten; Neuman, Andrew; Washenfelder, Rebecca; Brown, Steven; Baasandroj, Munkhbayar; Burkholder, James; Burling, Ian; Johnson, Timothy J.; Yokelson, Robert L.; de Gouw, Joost A.

    2010-07-23

    A negative-ion proton transfer chemical ionization mass spectrometric technique (NI-PT-CIMS), using acetate as the reagent ion, was applied to the measurement of volatile inorganic acids of atmospheric interest: hydrochloric (HCl), nitrous (HONO) nitric (HNO3), and isocyanic (HNCO) acids. Gas phase calibrations through the sampling inlet showed the method to be intrinsically sensitive (6-16 cts/pptv), but prone to inlet effects for HNO3 and HCl. The ion chemistry was found to be insensitive to water vapor concentrations, in agreement with previous studies of carboxylic acids. The inlet equilibration times for HNCO and HONO were 2 to 4 seconds, allowing for measurement in biomass burning studies. Several potential interferences in HONO measurements were examined: decomposition of HNO3•NO3- clusters within the CIMS, and NO2-water production on inlet surfaces, and were quite minor (>_1%, 3.3%, respectively). The detection limits of the method were limited by the instrument backgrounds in the ion source and flow tube, and were estimated to range between 16 and 50 pptv (parts per trillion by volume). The comparison of HONO measured by CIMS and by in situ FTIR showed good correlation and agreement to within 17%. The method provided rapid and accurate measurements of HNCO and HONO in controlled biomass burning studies, and suggest both as products of biomass burning.

  12. Improvement of microwave-assisted digestion of milk powder with diluted nitric acid using oxygen as auxiliary reagent

    NASA Astrophysics Data System (ADS)

    Bizzi, Cezar A.; Barin, Juliano S.; Garcia, Edivaldo E.; Nóbrega, Joaquim A.; Dressler, Valderi L.; Flores, Erico M. M.

    2011-05-01

    The feasibility of using diluted HNO 3 solutions under oxygen pressure for decomposition of whole and non-fat milk powders and whey powder samples has been evaluated. Digestion efficiency was evaluated by determining the carbon content in solution (digests) and the determination of Ca, Cd, Cu, Fe, K, Mg, Mn, Mo, Na, Pb and Zn was performed by inductively coupled plasma optical emission spectrometry and Hg by chemical vapor generation coupled to inductively coupled plasma mass spectrometry. Samples (up to 500 mg) were digested using HNO 3 solutions (1 to 14 mol L - 1 ) and the effect of oxygen pressure was evaluated between 2.5 and 20 bar. It was possible to perform the digestion of 500 mg of milk powder using 2 mol L - 1 HNO 3 with oxygen pressure ranging from 7.5 to 20 bar with resultant carbon content in digests lower than 1700 mg L - 1 . Using optimized conditions, less than 0.86 mL of concentrated nitric acid (14 mol L - 1 ) was enough to digest 500 mg of sample. The accuracy was evaluated by determination of metal concentrations in certified reference materials, which presented an agreement better than 95% (Student's t test, P < 0.05) for all the analytes.

  13. ReaxFF molecular dynamics simulations of intermediate species in dicyanamide anion and nitric acid hypergolic combustion

    NASA Astrophysics Data System (ADS)

    Weismiller, Michael R.; Junkermeier, Chad E.; Russo, Michael F., Jr.; Salazar, Michael R.; Bedrov, Dmitry; van Duin, Adri C. T.

    2015-10-01

    Ionic liquids based on the dicyanamide anion (DCA) are of interest as replacements for current hypergolic fuels, which are highly toxic. To better understand the reaction dynamics of these ionic liquid fuels, this study reports the results of molecular dynamics simulations performed for two predicted intermediate compounds in DCA-based ionic liquids/nitric acid (HNO3) combustion, i.e. protonated DCA (DCAH) and nitro-dicyanamide-carbonyl (NDC). Calculations were performed using a ReaxFF reactive force field. Single component simulations show that neat NDC undergo exothermic decomposition and ignition. Simulations with HNO3 were performed at both a low (0.25 g ml-1) and high (1.00 g ml-1) densities, to investigate the reaction in a dense vapor and liquid phase, respectively. Both DCAH and NDC react hypergolically with HNO3, and increased density led to shorter times for the onset of thermal runaway. Contrary to a proposed mechanism for DCA combustion, neither DCAH nor NDC are converted to 1,5-Dinitrobiuret (DNB) before thermal runaway. Details of reaction pathways for these processes are discussed.

  14. Measurements of HNO3, SO2 High Resolution Aerosol SO4 (sup 2-), and Selected Aerosol Species Aboard the NASA DC-8 Aircraft: During the Transport and Chemical Evolution Over the Pacific Airborne Mission (TRACE-P)

    NASA Technical Reports Server (NTRS)

    Talbot, Robert W.; Dibb, Jack E.

    2004-01-01

    The UNH investigation during TRACE-P provided measurements of selected acidic gases and aerosol species aboard the NASA DC-8 research aircraft. Our investigation focused on measuring HNO3, SO2, and fine (less than 2 microns) aerosol SO4(sup 2-) with two minute time resolution in near-real-time. We also quantified mixing ratios of aerosol ionic species, and aerosol (210)Pb and (7)Be collected onto bulk filters at better than 10 minute resolution. This suite of measurements contributed extensively to achieving the principal objectives of TRACE-P. In the context of the full data set collected by experimental teams on the DC-8, our observations provide a solid basis for assessing decadal changes in the chemical composition and source strength of Asian continental outflow. This region of the Pacific should be impacted profoundly by Asian emissions at this time with significant degradation of air quality over the next few decades. Atmospheric measurements in the western Pacific region will provide a valuable time series to help quantify the impact of Asian anthropogenic activities. Our data also provide important insight into the chemical and physical processes transforming Asian outflow during transport over the Pacific, particularly uptake and reactions of soluble gases on aerosol particles. In addition, the TRACE-P data set provide strong constraints for assessing and improving the chemical fields simulated by chemical transport models.

  15. HCl Vapour Pressures and Reaction Probabilities for ClONO2 + HCl on Liquid H2SO4-HNO3-HCl-H20 Solutions

    NASA Technical Reports Server (NTRS)

    Elrod, M. J.; Koch, R. E.; Kim, J. E.; Molina, M. J.

    1995-01-01

    Henry's Law solubility constants for HCl have been measured for liquid H2SO4-HNO3-HCl-H2O solutions; the results are in good agreement with predictions from published semiempirical models. The ClONO2 + HCl reaction on the surfaces of such solutions with compositions simulating those of stratospheric aerosols has been investigated; as the composition changes following the temperature drop characteristic of the high-latitude stratosphere the reaction probability gamma increases rapidly. Furthermore, the gamma values remain essentially unchanged when HN03 uptake is neglected; the controlling factor appears to be the solubility of HCl. These results corroborate our earlier suggestion that supercooled liquid sulfate aerosols promote chlorine activation at low temperatures as efficiently as solid polar stratospheric cloud particles.

  16. H 2SO 4/HNO 3/HCl—Functionalization and its effect on dispersion of carbon nanotubes in aqueous media

    NASA Astrophysics Data System (ADS)

    Osorio, A. G.; Silveira, I. C. L.; Bueno, V. L.; Bergmann, C. P.

    2008-12-01

    Chemical functionalization is a procedure used in materials science to oxidize the surface of materials. Several researchers use this technique to improve carbon nanotubes (CNTs) interaction and dispersion. The present article evaluates the effect of different functionalization methodologies on dispersion of CNTs in aqueous media. Sulfuric, nitric and chloridric acids were used on the first functionalization. For the second procedure tested the addition of chloridric acid was eliminated; and the third functionalization was done using only nitric acid. Experimental results obtained by Raman spectroscopy indicated the maintenance of the structure of CNTs after all oxidations. The presence of other structures was proved by thermogravimetry decomposition and the addition of functional groups was confirmed by transform Fourier infrared spectroscopy. From these experimental results, we conclude that all methodologies used showed a percentage of adsorption of functional groups on the CNTs. However, based on dispersion analysis in aqueous media, it is observed that this adsorption showed more efficiency on the first functionalization method, followed by the second method.

  17. Copper corrosion mechanism in the presence of formic acid vapor for short exposure times

    SciTech Connect

    Bastidas, J.M.; Lopez-Delgado, A.; Cano, E.; Polo, J.L.; Lopez, F.A.

    2000-03-01

    The rate of copper corrosion originated by the action of formic acid vapors at 100% relative humidity was studied. Five formic vapor concentration levels (10, 50, 100, 200, and 300 ppm) were used. A copper corrosion rate of up to 1,300 mg/m{sup 2} d was measured for a period of 21 days using a gravimetric method. The patina layers were characterized using cathodic reduction, X-ray powder diffraction. Fourier transform infrared spectrometry, and scanning electron microscopy techniques. Some of the components identified in the corrosion-product layers were cuprite (Cu{sub 2}O), cupric hydroxide hydrate [Cu(OH){sub 2}{sm_bullet}H{sub 2}O], and copper formate hydrate [Cu(HCOO){sub 2}{sm_bullet}4H{sub 2}O]. The latter was formed by both cupric hydroxide and formic acid-cuprous ion complex mechanisms.

  18. An intercomparison of measurement systems for vapor and particulate phase concentrations of formic and acetic acids

    NASA Technical Reports Server (NTRS)

    Keene, William C.; Talbot, Robert W.; Andreae, Meinrat O.; Beecher, Kristene; Berresheim, Harold

    1989-01-01

    During June 1986, eight systems for measuring vapor phase and four for measuring particulate phase concentrations of formic acid (HCOOH) and acetic acid (CH3COOH) were intercompared in central Virginia. HCOOH and CH3COOH vapors were sampled by condensate, mist, Chromosorb 103 GC resin, NaOH-coated annular denuders, NaOH-impregnated quartz filters, K2CO3 and NaCO3-impregnated cellulose filters, and Nylasorb membranes. Atmospheric aerosol was collected on Teflon and Nuclepore filters using both hi-vol and lo-vol systems to measure particulate phase concentrations. Performances of the mist chamber and K2CO3-impregnated filter techniques were evaluated using zero air and ambient air spiked with HCOOH(g) and CH3COOH(g), and formaldehyde from permeation sources. The advantages and drawbacks of these methods are reported and discussed.

  19. In situ direct measurement of vapor pressures and thermodynamic parameters of volatile organic materials in the vapor phase: benzoic acid, ferrocene, and naphthalene.

    PubMed

    Hikal, Walid M; Weeks, Brandon L

    2013-06-24

    We report the direct determination of vapor pressures and optical and thermodynamic parameters of powders of low-volatile materials in their vapor phase using a commercial UV/Vis spectrometer. This methodology is based on the linear proportionality between the density of the saturated gas of the material and the absorbance of the gas at different temperatures. The vapor pressure values determined for benzoic acid and ferrocene are in good agreement with those reported in the literature with ∼2-7 % uncertainty. Thermodynamic parameters of benzoic acid, ferrocene, and naphthalene are determined in situ at temperatures below their melting points. The sublimation enthalpies of the investigated organic molecules are in excellent agreement with the ICTAC recommended values (less than 1 % difference). This method has been used to measure vapor pressures and thermodynamic parameters of organic volatile materials with vapor pressures of ∼0.5-355 Pa in the 50-100 °C temperature range. PMID:23606455

  20. A laboratory study of the effect of acetic acid vapor on atmospheric copper corrosion

    SciTech Connect

    Lopez-Delgado, A.; Cano, E.; Bastidas, J.M.; Lopez, F.A.

    1998-12-01

    A study was made of the copper corrosion rate and corrosion products originated by the action of acetic acid vapor at 100% relative humidity. Copper plates were exposed to an acetic acid contaminated atmosphere for a period of 21 days. Five acetic vapor concentration levels were used. The copper corrosion rate was in the range of 1 to 23 mg/dm{sup 2} day. The corrosion-product layers were characterized using electrochemical, X-ray powder diffraction, Fourier transform infrared spectrometry, and scanning electron microscopy techniques. Thermal and calorimetric studies were also performed. Some of the compounds identified were cuprite (Cu{sub 2}O), copper acetate hydrate [Cu(CH{sub 3}COO){sub 2}{center_dot}2H{sub 2}O], and copper hydroxide acetate [Cu{sub 4}(OH)(CH{sub 3}COO){sub 7}{center_dot}2H{sub 2}O]. This last compound was also characterized. The thickness of the patina layers was 4 to 8 nm for amorphous cuprite, 11 to 48 nm for cuprite, and 225 nm for copper acetate. The patina, in which the cementation process of different corrosion-product layers plays an important role, is formed by the reaction of acetic vapor with copper through porous cuprite paths.

  1. Acid effects on the measurement of mercury by cold vapor atomic absorption spectrometry

    SciTech Connect

    Adeloju, S.B.; Mann, T.F.

    1987-07-01

    The influence of nitric, hydrochloric and sulfuric acids on the measurement of mercury by cold vapor atomic absorption spectrometry has been investigated. Small pre-reduction peaks associated with the instability of mercury were observed in solutions containing less than or equal to 12.5, < 2 and less than or equal to 12.5% v/v of each acid, respectively. Mercury was found to be most stable in greater than or equal to 2% v/v hydrochloric acid and the measured absorbance was not greatly influenced by varying concentration of the acid. The mercury absorbance measurements were more sensitive in solutions containing less than or equal to 6.3% v/v hydrochloric acid than in similar concentrations of nitric and sulfuric acids. The use of the three acids as a digestion mixture result in serious interference from nitrogen oxides. The interference was removed by use of expelling agents such as urea and sulfamic acid or overcome by use of excess stannous chloride, prior to the reduction of mercury(II) ions. The determination of mercury in NBS albacore tuna using both of these approaches to overcome the interference problem proved to be successful.

  2. Determination of Reactive Nitrogen Species (NOx, NOy-HNO3, Peroxyacetyl Nitrates, Total Organic Nitrates) During the PROPHET Summer 2008 Intensive

    NASA Astrophysics Data System (ADS)

    Alaghmand, M.; Slade, N. J.; Mielke, L.; Starn, T.; Carroll, M.; Bertman, S. B.; Stevens, P. S.; Shepson, P. B.

    2008-12-01

    Determinations of NOx, NOy-HNO3, peroxyacetyl nitrates (PANs) and total organic nitrates (∑RONO2) were made during the summer 2008 intensive of the Program for Research on Oxidants: Photochemistry, Emissions and Transport (PROPHET). The Total Reactive Nitrogen Instrument (TRENI), a high sensitivity instrument, is capable of speciating atmospheric nitrogen species. TRENI, a chemiluminescence analyzer with two inlet systems (photolytic cell and heated gold tube) was employed to quantify NO, NO2 and NOy. Another inlet system comprised of thermal dissociation reactors, was employed to speciate NOy components into NOx, PANs and ∑RONO2. The detection limit of TRENI is 5 ppt for NOx and NOy and 20 ppt for total organic nitrates and PANs. In this study, we examine the extent to which we can explain the ∑RONO2 concentrations with known precursors and/or individual RONO2 measurement data. The observed fraction of NOy attributable to the ∑RONO2 is much higher than from previous individual RONO2 measurements. It seems clear that there is a large component of 'missing NOy' in the ∑RONO2 channel, as observed by others using the thermal dissociation inlet approach. We also examine here the potential sources of the frequently observed morning pulse of NOx, and the potential role of the forest canopy in mediating nitrogen chemistry.

  3. Retrieval of stratospheric O3, HNO3, and ClONO2 profiles from 1992 MIPAS-B limb emission spectra: method, results, and error analysis

    NASA Astrophysics Data System (ADS)

    Clarmann, T. von; Fischer, H.; Friedl-Vallon, F.; Linden, A.; Oelhaf, H.; Piesch, C.; Seefeldner, M.; Völker, W.

    1993-11-01

    Within the framework of the European Arctic Stratospheric Ozone Experiment, two flights of the balloon-borne MIPAS-B limb emission spectrometer were performed in the Arctic stratosphere from Kiruna, northern Sweden. During the early hours of January 13 and the night from March 14 to March 15, 1992, several limb sequences of infrared spectra were recorded which have permitted the retrieval of vertical profiles of many trace gases relevant for ozone chemistry. In the present work, the retrieval strategy, error estimation strategy, and resulting profiles of O3, HNO3, and ClONO2 are reported. The data analysis procedure, consisting of data preprocessing including calibration, analysis of auxiliary data including temperature profiles and line of sight determination, and retrieval of trace gas profiles, is described in detail. The last is carried out by means of multiparameter nonlinear least squares fitting in combination with onion peeling. An astonishingly high ClONO2 amount of 2.6 ppb by volume at about 19-km altitude was inferred for the March flight. A rigorous error analysis, which takes into account systematic and random errors and their often nonlinear impact on the results, proves the significance of the retrieved trace gas profiles.

  4. Photolysis of Nitric Acid and Nitrate on Natural and Artificial Surfaces.

    PubMed

    Ye, Chunxiang; Gao, Honglian; Zhang, Ning; Zhou, Xianliang

    2016-04-01

    Photolysis of nitric acid and nitrate (HNO3/nitrate) was investigated on the surfaces of natural and artificial materials, including plant leaves, metal sheets, and construction materials. The surfaces were conditioned in the outdoor air prior to experiments to receive natural depositions of ambient HNO3/nitrate and other atmospheric constituents. The photolysis rate constant (JHNO3(s)) of the surface HNO3/nitrate was measured based on the production rates of nitrous acid (HONO) and nitrogen oxides (NOx). The JHNO3(s) values, from 6.0 × 10(-6) s(-1) to 3.7 × 10(-4) s(-1), are 1 to 3 orders of magnitude higher than that of gaseous HNO3. The HONO was the major product from photolysis of HNO3/nitrate on most plant leaves, whereas NOx was the major product on most artificial surfaces. The JHNO3(s) values decreased with HNO3/nitrate surface density and could be described by a simple analytical equation. Within a typical range of HNO3/nitrate surface density in the low-NOx forested areas, photolysis of HNO3/nitrate on the forest canopy can be a significant source for HONO and NOx for the overlying atmosphere. PMID:26936001

  5. Strong Fluorescent Smart Organogel as a Dual Sensing Material for Volatile Acid and Organic Amine Vapors.

    PubMed

    Xue, Pengchong; Yao, Boqi; Wang, Panpan; Gong, Peng; Zhang, Zhenqi; Lu, Ran

    2015-11-23

    An L-phenylalanine derivative (C12PhBPCP) consisting of a strong emission fluorophore with benzoxazole and cyano groups is designed and synthesized to realize dual responses to volatile acid and organic amine vapors. The photophysical properties and self-assembly of the said derivative in the gel phase are also studied. C12PhBPCP can gelate organic solvents and self-assemble into 1 D nanofibers in the gels. UV/Vis absorption spectral results show H-aggregate formation during gelation, which indicates strong exciton coupling between fluorophores. Both wet gel and xerogel emit strong green fluorescence because the cyano group suppresses fluorescence quenching in the self-assemblies. Moreover, the xerogel film with strong green fluorescence can be used as a dual chemosensor for quantitative detection of volatile acid and organic amine vapors with fast response times and low detection limits owing to its large surface area and amplified fluorescence quenching. The detection limits are 796 ppt and 25 ppb for gaseous aniline and trifluoroacetic acid (TFA), respectively.

  6. Vaporization-condensation-recrystallization process-mediated synthesis of helical m-aminobenzoic acid nanobelts.

    PubMed

    Yoon, Seok Min; Hwang, In-Chul; Shin, Namsoo; Ahn, Docheon; Lee, Sang Joo; Lee, Jin Yong; Choi, Hee Cheul

    2007-11-01

    One-dimensional (1D) helical organic nanostructures were synthesized by a modified vapor-solid (VS) process, called the vaporization-condensation-recrystallization (VCR) process. The conventional solution-phase synthetic methods generally mediate self-assemblies of repeating unit molecules. To provide enough intermolecular interaction forces among the unit molecules, such strategy requires specific designs and syntheses of complex unit molecules as they possess numerous functional groups including phenyl rings, hydroxyl groups, long aliphatic chains, etc. On the contrary, we found that small and simple organic molecules, for example, m-ABA, could be self-assembled by the VCR process, resulting in 1D helical organic nanostructures. When m-aminobenzoic acid (m-ABA) powders were vaporized and transported to be condensed on a cooler region, the condensates were recrystallized into 1D helical nanobelts. Each step of the VCR process was confirmed from control experiments performed by varying reaction times, substrate types, and reaction temperatures. Powder XRD data, SAED analysis, and theoretical calculations revealed that dimers of m-ABA molecules have repeating units, and the growth axis of m-ABA nanohelices is [100].

  7. The effect of heat treatment on the corrosion resistance of 440C stainless steel in 20% HNO3 + 2.5% Na2Cr2O7 solution

    NASA Astrophysics Data System (ADS)

    Savas, Terence P.; Wang, Allen Yi-Lan; Earthman, James C.

    2003-04-01

    The effect of heat treatment on the corrosion resistance of 440C stainless steel was investigated in a 20% HNO3 + 2.5% Na2Cr2O7 solution using electrochemical noise (ECN) measurements, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) examinations. The noise resistance ( Rn), which has been found to be inversely related to the localized corrosion rate, was measured to be 5.7E + 08 Ω-cm2, 4.2E + 08 Ω-cm2, and 3.7E + 04 Ω-cm2 for the oil-quenched, air-quenched, and vacuum furnace cooled (VFC) samples, respectively, after 1200 s exposures. The Rn for all heat treat conditions stabilized within a range of 1.0E + 07 Ω-cm2 to 3.2E + 08 Ω-cm2 after 2 h exposures. The EIS response showed a polarization resistance ( R p) on the order of 6.6E + 04 Ω-cm2, 5.3E + 04 Ω-cm2, and 1.1E + 04 Ω-cm2 for the oil-quenched, air-quenched, and VFC samples, respectively, after 2 h exposures. The EIS data are in good agreement with ECN data and indicate that after longer exposures, general corrosion mechanisms dominate and the corrosion rates are comparable. SEM examinations of specimens subjected to 1200 s exposures revealed that severity of pitting and intergranular corrosion damage was consistent with trends in the Rn data. Specifically, the electrochemical noise data as well as SEM examinations of specimens revealed a higher localized corrosion resistance of the hardened specimens during the early stages of passivation. This greater resistance to localized corrosion can be attributed to an increased stability of the natural passive film resulting from a higher concentration of chromium atoms in solution for the martensite phase.

  8. Simulating the phase partitioning of NH3, HNO3, and HCl with size-resolved particles over northern Colorado in winter

    NASA Astrophysics Data System (ADS)

    Kelly, James T.; Baker, Kirk R.; Nolte, Christopher G.; Napelenok, Sergey L.; Keene, William C.; Pszenny, Alexander A. P.

    2016-04-01

    Numerical modeling of inorganic aerosol processes is useful in air quality management, but comprehensive evaluation of modeled aerosol processes is rarely possible due to the lack of comprehensive datasets. During the Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT) campaign in February and March 2011, the phase partitioning of soluble trace gases with size-resolved particles and related meteorological conditions were measured continuously at a site in Colorado about 33 km north of Denver. These size-resolved measurements of particulate SO42- , NH4+, NO3- , Cl-, Na+, Ca2+, Mg2+, and K+ and inorganic gases are used here to assess the ability of a continental U.S. modeling platform to simulate the gas-particle partitioning of NH3, HNO3, and HCl at this location. Modeling is based on the Community Multiscale Air Quality (CMAQ) model with 12 km horizontal resolution. Baseline, sensitivity, and source apportionment simulations are conducted to fully characterize the model predictions. Considering the limitations in representing regional terrain features in the national 12 km modeling, predictions agree reasonably well with measured concentrations and gas-particle partitioning at this location. However, the median sum of NH4+ and NH3 is underpredicted in the baseline simulation by a factor of four suggesting a need for improved bottom-up NH3 emissions inventories in this area. The median sum of Cl- and HCl is underpredicted by a factor of 2.8, while levels of Ca2+, Mg2+, and K+ are overpredicted. Improvements in windblown and fugitive dust emissions may improve and/or better constrain these predictions. Mass size distributions for inorganic particle constituents are generally simulated well, although the modeled fine particle mode is shifted to slightly larger diameters relative to measurements. Source apportionment modeling estimates of source sector and boundary contributions to air quality at the site are provided.

  9. An Investigation of Solid-State Amidization and Imidization Reactions in Vapor Deposited Poly (amic acid)

    SciTech Connect

    Anthamatten, M; Letts, S A; Day, K; Cook, R C; Gies, A P; Hamilton, T P; Nonidez, W K

    2004-06-28

    The condensation polymerization reaction of 4,4'-oxydianiline (ODA) with pyromellitic dianhydride (PMDA) to form poly(amic acid) and the subsequent imidization reaction to form polyimide were investigated for films prepared using vapor deposition polymerization techniques. Fourier-transform infrared spectroscopy (FT-IR), thermal analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of films at different temperatures indicate that additional solid-state polymerization occurs prior to imidization reactions. Experiments reveal that, upon vapor deposition, poly(amic acid) oligomers form that have a number-average molecular weight of about 1500 Daltons. Between 100 - 130 C these chains undergo additional condensation reaction to form slightly higher molecular weight oligomers. Calorimetry measurements show that this reaction is exothermic ({Delta}H {approx} -30 J/g) with an activation energy of about 120 kJ/mol. Experimental reaction enthalpies are compared to results from ab initio molecular modeling calculations to estimate the number of amide groups formed. At higher temperatures (150 - 300 C) imidization of amide linkages occurs as an endothermic reaction ({Delta}H {approx} +120 J/g) with an activation energy of about 130 kJ/mol. Solid-state kinetics were found to depend on reaction conversion as well as the processing conditions used to deposit films.

  10. Vapor Phase Dehydration of Glycerol to Acrolein Over SBA-15 Supported Vanadium Substituted Phosphomolybdic Acid Catalyst.

    PubMed

    Viswanadham, Balaga; Srikanth, Amirineni; Kumar, Vanama Pavan; Chary, Komandur V R

    2015-07-01

    Vapor phase dehydration of glycerol to acrolein was investigated over heteropolyacid (HPA) catalysts containing vanadium substituted phosphomolybdic acid (H4PMo11VO40) supported on mesoporous SBA-15. A series of HPA catalysts with HPA loadings varying from 10-50 wt% were prepared by impregnation method on SBA-15 support. The catalysts were characterized by X-ray diffraction, Raman spectroscopy, Fourier Transform infrared spectroscopy, temperature-programmed desorption of NH3, pyridine adsorbed FT-IR spectroscopy, scanning electron microscopy, pore size distribution and specific surface area measurements. The nature of acidic sites was examined by pyridine adsorbed FT-IR spectroscopy. XRD results suggest that the active phase containing HPA was highly dispersed at lower loadings on the support. FT-IR and Raman spectra results confirm that the presence of primary Keggin ion structure of HPA on the support and it was not affected during the preparation of catalysts. Pore size distribution results reveal that all the samples show unimodel pore size distribution with well depicted mesoporous structure. NH3-TPD results suggest that the acidity of catalysts increased with increase of HPA loading. The findings of acidity measurements by FT-IR spectra of pyridine adsorption reveals that the catalysts consist both the Brønsted and Lewis acidic sites and the amount of Brønsted acidic sites are increasing with HPA loading. SBA-15 supported vanadium substituted phosphomolybdic acid catalysts are found to be highly active during the dehydration reaction and exhibited 100% conversion of glycerol (10 wt% of glycerol) and the acrolein selectivity was appreciably changed with HPA active phase loading. The catalytic functionalities during glycerol dehydration are well correlated with surface acidity of the catalysts.

  11. Sulfuric acid vapor and other cloud-related gases in the Venus atmosphere - Abundances inferred from observed radio opacity

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.; Eshleman, V. R.

    1982-01-01

    It is suggested that the absorbing characteristics of sulfuric acid vapor appear to reconcile what had been thought to be an inconsistency among measurements and deductions regarding the constituents of the Venus atmosphere and radio occultation, radar reflection, and radio emission measurements of its opacity. Laboratory measurements of sulfuric acid, sulfur dioxide, water vapor, and carbon dioxide are used to model relative contributions to opacity as a function of height in a way that is consistent with observations of the constituents and absorbing properties of the atmosphere. It is concluded that sulfuric acid vapor is likely to be the principal microwave absorber in the 30-50 km altitude range of the middle atmosphere of Venus.

  12. Vapor pressures and lattice energies of oxalic acid, mesotartaric acid, phloroglucinol, myoinositol, and their hydrates

    NASA Astrophysics Data System (ADS)

    de Wit, H. G. M.; Bouwstra, J. A.; Blok, J. G.; de Kruif, C. G.

    1983-02-01

    In the present investigation, we report the enthalpy of dehydration and the enthalpy of sublimation of a number of organic hydrates and their anhydrous counterparts. These values are used to test the transferability of a set of atom-atom potential parameters, originally derived for carboxylic acids. The calculations showed that the parameter set was transferable to a fairly good degree.

  13. Penetration of methyl isocyanate through organic vapor and acid gas respirator cartridges

    SciTech Connect

    Moyer, E.S.; Berardinelli, S.P.

    1987-04-01

    Methyl isocyanate (MIC) is a volatile, toxic chemical used to manufacture carbamate pesticides. In light of the December 1984 Bhopal, India disaster and possible safety problems at the Institute facility, NIOSH conducted this research as a basis upon which to recommend protective equipment that might be used in an emergency situation where extremely high MIC concentrations might be encountered. Both protective clothing and respirators were evaluated. In particular, NIOSH studies air-purifying respirators in order to assess their effectiveness against MIC vapor penetration. NIOSH does not recommend any air purifying respirator for MIC because of its high toxicity and lack of warming properties and because no effective end of service life indicator currently is available for MIC. This report addresses only MIC penetration through air-purifying cartridges at challenge concentration designed to simulate emergency escape conditions. The results presented are for two different manufacturers' organic vapor (OV) and acid gas cartridges. Penetration tests were conducted at three or four MIC challenge concentrations and at three different humidity conditions. In general, breakthrough times (1% of challenge concentration) were very short (<20 min). Also, high relative humidity was found to decrease the breakthrough time of MIC.

  14. Penetration of methyl isocyanate through organic vapor and acid gas respirator cartridges.

    PubMed

    Moyer, E S; Berardinelli, S P

    1987-04-01

    Methyl isocyanate (MIC) is a volatile, toxic chemical [Threshold Limit Value (TLV) = 0.02 ppm] used to manufacture carbamate pesticides. The principal manufacturer of MIC is Union Carbide, and the site of production is Institute, West Virginia. In light of the December 1984 Bhopal, India disaster and possible safety problems at the Institute facility, NIOSH conducted this research as a basis upon which to recommend protective equipment that might be used in an emergency situation where extremely high MIC concentrations might be encountered. Both protective clothing and respirators were evaluated. In particular, NIOSH studied air-purifying respirators in order to assess their effectiveness against MIC vapor penetration. NIOSH does not recommend any air purifying respirator for MIC because of its high toxicity and lack of warning properties and because no effective end of service life indicator currently is available for MIC. This report addresses only MIC penetration through air-purifying cartridges at challenge concentrations designed to simulate emergency escape conditions. Another report addresses the protective clothing issue. The results presented are for two different manufacturers' organic vapor (OV) and acid gas cartridges. Penetration tests were conducted at three or four MIC challenge concentrations and at three different humidity conditions. In general, breakthrough times (1% of challenge concentration) were very short (less than 20 min). Also, high relative humidity was found to decrease the breakthrough time of MIC. PMID:3591646

  15. SMILES zonal and diurnal variation climatology of stratospheric and mesospheric trace gasses: O3, HCl, HNO3, ClO, BrO, HOCl, HO2, and temperature

    NASA Astrophysics Data System (ADS)

    Kreyling, Daniel; Sagawa, Hideo; Wohltmann, Ingo; Lehmann, Ralph; Kasai, Yasuko

    2013-10-01

    We present a climatology of the diurnal variation of short-lived atmospheric compounds, such as ClO, BrO, HO2, and HOCl, as well as longer-lived species: O3, the hydrogen chloride isotopes H35Cl and H37Cl, and HNO3. Measurements were taken by the Superconducting Submillimeter-wave Limb-Emission Sounder (SMILES). This spectrally resolving radiometer, with very low observation noise and altitude range from the lower stratosphere to the lower thermosphere (20-100km), was measuring vertical profiles of absorption spectra along a non-sun-synchronous orbit, thus observing at all local times. We used the retrieved volume mixing ratio profiles to compile climatologies that are a function of pressure, a horizontal coordinate (latitude or equivalent latitude), and a temporal coordinate (solar zenith angle or local solar time). The main product presented are climatologies with a high resolution of the temporal coordinate (diurnal variation climatologies). In addition, we provide climatologies with a high resolution of the horizontal coordinate (zonal climatologies).The diurnal variation climatologies are based on data periods of 2 months and the zonal climatologies on monthly data periods. Consideration of the SMILES time-space sampling patterns with respect to the averaging coordinates is a key issue for climatology creation, especially in case of diurnal variation climatologies. Biases induced by inhomogeneous sampling are minimized by carefully choosing the size of averaging bins. The sampling biases of the diurnal variation climatology of ClO and BrO are investigated in a comparison of homogeneously sampled model data versus SMILES-sampled model data from the stratospheric Lagrangian chemistry and transport model Alfred Wegener Institute Lagrangian Chemisrty/Transport System. In most cases, the relative sampling error is in the range of 0-20%. The strongest impact of sampling biases is found where the species' temporal gradients are strongest (mostly at sunrise and sunset

  16. Vapor phase ketonization of acetic acid on ceria based metal oxides

    SciTech Connect

    Liu, Changjun; Karim, Ayman M.; Lebarbier, Vanessa MC; Mei, Donghai; Wang, Yong

    2013-12-01

    The activities of CeO2, Mn2O3-CeO2 and ZrO2-CeO2 were measured for acetic acid ketonization under reaction conditions relevant to pyrolysis vapor upgrading. We show that the catalyst ranking changed depending on the reaction conditions. Mn2O3-CeO2 was the most active catalyst at 350 oC, while ZrO2 - CeO2 was the most active catalyst at 450 oC. Under high CO2 and steam concentration in the reactants, Mn2O3-CeO2 was the most active catalyst at 350 and 450 °C. The binding energies of steam and CO2 with the active phase were calculated to provide the insight into the tolerance of Mn2O3-CeO2 to steam and CO2.

  17. MW Spectroscopy Coupled with Ultrafast UV Laser Vaporization: Succinic Acid in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Mendez, Estibaliz; Ecija, Patricia; Cocinero, Emilio J.; Castano, Fernando; Basterretxea, Francisco J.; Godfrey, Peter D.; McNaughton, Don; Jahn, Michaela K.; Nair, K. P. Rajappan; Grabow, Jens-Uwe

    2013-06-01

    Recent lab and field measurements have indicated critical roles of organic acids in enhancing new atmospheric aerosol formation. In order to understand the nucleation process, here we report an experimental and theoretical investigation of chemical structure of succinic acid. We have used the technique of Fourier Transform Microwave Spectroscopy (FTMW). Succinic acid was vaporized by UV ultrafast laser ablation to suppress thermal decomposition processes^a and seeded into an expanding stream of Ne forming a supersonic jet. The rotational spectrum detected the presence of a single most stable conformation in the cm- mm- wave regions for which accurate rotational and centrifugal distortion parameters have been determined. The study was extended to all monosubstituted isotopic species (^{13}C, ^{18}O, D(O)), which were positively identified, leading to an accurate determination of the effective and substitution structures of the molecule. The experimental study was supplemented by ab initio (MP2) and DFT (M06-2X and B3LYP) calculations. ^{a} E. J. Cocinero, A. Lesarri, P. écija, F. J. Basterretxea, J. U. Grabow, J. A. Fernández and F. Castaño, Angew. Chem. Int. Ed., 51, 3119-3124, 2012.

  18. Measurements of tropospheric nitric acid over the Western United States and Northeastern Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Lebel, P. J.; Huebert, B. J.; Schiff, H. I.; Vay, S. A.; Vanbramer, S. E.; Hastie, D. R.

    1990-01-01

    Over 240 measurements of nitric acid (HNO3) were made in the free troposphere as well as in the boundary layer. Marine HNO3 measurement results were strikingly similar to results from GAMETAG and other past atmospheric field experiments. The marine boundary layer HNO3 average, 62 parts-per-trillion by volume (pptv), was 1/3 lower than the marine free tropospheric average, 108 pptv, suggesting that the boundary layer is a sink for tropospheric nitric acid, probably by dry deposition. Nitric acid measurements on a nighttime continental flight gave a free tropospheric average of 218 pptv, substantially greater than the daytime continental free tropospheric 5-flight average of 61 pptv. However, the nighttime results may be influenced by highly convective conditions that existed from thunderstorms in the vicinity during that night flight. The continental boundary layer HNO3 average of 767 pptv is an order of magnitude greater than the free tropospheric average, indicating that the boundary layer is a source of free tropospheric HNO3. The distribution of continental boundary layer HNO3 data, from averages of 123 over rural Nevada and Utah to 1057 pptv in the polluted San Joaquin Valley of California suggest a close tie between boundary layer HNO3 and anthropogenic activity.

  19. Heterogeneous reactions of HNO3(g) + NaCl(s) yields HCl(g) + NaNO3(s) and N2O5(g) + NaCl(s) yields ClNO2(g) + NaNO3(s)

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun; Timonen, Raimo S.; Keyser, Leon F.; Yung, Yuk L.

    1995-01-01

    The heterogeneous reactions of HNO3(g) + NaCl(s) yields HCl(g) + NaNO3(s) (eq 1) and N2O5(g) + NaCl(s) yields ClNO2(g) + NaNO3(S) (eq 2) were investigated over the temperature range 223-296 K in a flow-tube reactor coupled to a quadrupole mass spectrometer. Either a chemical ionization mass spectrometer (CIMS) or an electron-impact ionization mass spectrometer (EIMS) was used to provide suitable detection sensitivity and selectivity. In order to mimic atmospheric conditions, partial pressures of HNO3 and N2O5 in the range 6 x 10(exp -8) - 2 x 10(exp -6) Torr were used. Granule sizes and surface roughness of the solid NaCl substrates were determined by using a scanning electron microscope. For dry NaCl substrates, decay rates of HNO3 were used to obtain gamma(1) = 0.013 +/- 0.004 (1sigma) at 296 K and > 0.008 at 223 K, respectively. The error quoted is the statistical error. After all corrections were made, the overall error, including systematic error, was estimated to be about a factor of 2. HCl was found to be the sole gas-phase product of reaction 1. The mechanism changed from heterogeneous reaction to predominantly physical adsorption when the reactor was cooled from 296 to 223 K. For reaction 2 using dry salts, gamma(2) was found to be less than 1.0 x 10(exp -4) at both 223 and 296 K. The gas-phase reaction product was identified as ClNO2 in previous studies using an infrared spectrometer. An enhancement in reaction probability was observed if water was not completely removed from salt surfaces, probably due to the reaction of N2O5(g) + H2O(s) yields 2HNO3(g). Our results are compared with previous literature values obtained using different experimental techniques and conditions. The implications of the present results for the enhancement of the hydrogen chloride column density in the lower stratosphere after the El Chichon volcanic eruption and for the chemistry of HCl and HNO3 in the marine troposphere are discussed.

  20. Unravelling the potential of nitric acid as a surface modifier for improving the hemocompatibility of metallocene polyethylene for blood contacting devices

    PubMed Central

    Vellayappan, Muthu Vignesh; Muhamad, Ida Idayu

    2016-01-01

    Design of blood compatible surfaces is obligatory to minimize platelet surface interactions and improve the thromboresistance of foreign surfaces when they are utilized as biomaterials particularly for blood contacting devices. Pure metallocene polyethylene (mPE) and nitric acid (HNO3) treated mPE antithrombogenicity and hydrophilicity were investigated. The contact angle of the mPE treated with HNO3 decreased. Surface of mPE and HNO3 treated mPE investigated with FTIR revealed no major changes in its functional groups. 3D Hirox digital microscopy, SEM and AFM images show increased porosity and surface roughness. Blood coagulation assays prothrombin time (PT) and activated partial thromboplastin time (APTT) were delayed significantly (P < 0.05) for HNO3 treated mPE. Hemolysis assay and platelet adhesion of the treated surface resulted in the lysis of red blood cells and platelet adherence, respectively indicating improved hemocompatibility of HNO3 treated mPE. To determine that HNO3 does not deteriorate elastic modulus of mPE, the elastic modulus of mPE and HNO3 treated mPE was compared and the result shows no significant difference. Hence, the overall observation suggests that the novel HNO3 treated mPE may hold great promises to be exploited for blood contacting devices like grafts, catheters, and etc. PMID:26819837

  1. Pd clusters supported on amorphous, low-porosity carbon spheres for hydrogen production from formic acid.

    PubMed

    Bulushev, Dmitri A; Bulusheva, Lyubov G; Beloshapkin, Sergey; O'Connor, Thomas; Okotrub, Alexander V; Ryan, Kevin M

    2015-04-29

    Amorphous, low-porosity carbon spheres on the order of a few micrometers in size were prepared by carbonization of squalane (C30H62) in supercritical CO2 at 823 K. The spheres were characterized and used as catalysts' supports for Pd. Near-edge X-ray absorption fine structure studies of the spheres revealed sp(2) and sp(3) hybridized carbon. To activate carbons for interaction with a metal precursor, often oxidative treatment of a support is needed. We showed that boiling of the obtained spheres in 28 wt % HNO3 did not affect the shape and bulk structure of the spheres, but led to creation of a considerable amount of surface oxygen-containing functional groups and increase of the content of sp(2) hybridized carbon on the surface. This carbon was seen by scanning transmission electron microscopy in the form of waving graphene flakes. The H/C atomic ratio in the spheres was relatively high (0.4) and did not change with the HNO3 treatment. Palladium was deposited by impregnation with Pd acetate followed by reduction in H2. This gave uniform Pd clusters with a size of 2-4 nm. The Pd supported on the original C spheres showed 2-3 times higher catalytic activity in vapor phase formic acid decomposition and higher selectivity for H2 formation (98-99%) than those for the catalyst based on the HNO3 treated spheres. Using of such low-porosity spheres as a catalyst support should prevent mass transfer limitations for fast catalytic reactions.

  2. Sources of atmospheric acidity in an agricultural-industrial region of São Paulo State, Brazil

    NASA Astrophysics Data System (ADS)

    Da Rocha, G. O.; Franco, A.; Allen, A. G.; Cardoso, A. A.

    2003-04-01

    Surface-based measurements of atmospheric formic acid (HCOOH), acetic acid (CH3COOH), sulfur dioxide (SO2), hydrogen chloride (HCl), and nitric acid (HNO3) were made in central São Paulo State, Brazil, between April 1999 and March 2000. Mean concentrations were 9.0 ppb (HCOOH), 1.3 ppb (CH3COOH), 4.9 ppb (SO2), 0.3 ppb (HCl), and 0.5 ppb (HNO3). Concentrations in sugar cane burning plumes were 1160-4230 ppb (HCOOH), 360-1750 ppb (CH3COOH), 10-630 ppb (SO2), 4-210 ppb (HCl), and 14-90 ppb (HNO3). Higher ambient concentrations of SO2, HCl and HNO3 were measured during the burning season (May-November). Concentrations of SO2 and HCl increased during the evening, and of HCOOH and CH3COOH were lowest in the morning, with peak levels in the afternoon. Ratios obtained between different species showed either nighttime maxima (SO2/HCOOH, SO2/CH3COOH, SO2/HNO3, CH3COOH/HNO3, SO2/HCl and HCOOH/HNO3), daytime maxima (HCOOH/HCl, CH3COOH/HCl and HNO3/HCl), or no clear trends (HCOOH/CH3COOH). Correlation analysis showed that SO2 and HCl were primary emissions from biomass burning and road transport; HCOOH, HNO3 and CH3COOH were products of photochemistry; HCOOH and CH3COOH were emitted directly during combustion as well as from biogenic sources. Biomass burning affected atmospheric acidity on a regional scale, while vehicular emissions had greater impact in urban and adjacent areas. Atmospheric ammonia levels were insufficient to neutralize atmospheric acidity, which was mainly removed by deposition to the surface.

  3. An Investigation of the Solid-State Condensation Polymerization Reaction in Vapor-Deposited Poly(amic acid)

    NASA Astrophysics Data System (ADS)

    Anthamatten, Mitchell; Letts, Stephan A.; Day, Katherine; Cook, Robert C.; Gies, Anthony P.; Nonidez, William K.

    2004-03-01

    The condensation polymerization reaction of 4,4'-oxydianiline (ODA) with pyromellitic dianhydride (PMDA) to form poly(amic acid) and the subsequent imidization reaction to form polyimide were investigated for films prepared using vapor deposition polymerization techniques. Fourier-transform infrared spectroscopy (FTIR), thermal analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of films prepared at different temperatures indicate that additional solid-state polymerization occurs prior to imidization reactions. Experiments suggest that poly(amic acid) oligomers form upon vapor-deposition and have a number-average molecular weights of about 1500 Daltons. Between 100-130 °C these chains undergo additional condensation reactions to form slightly higher molecular weight oligomers. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

  4. On the acidity of dew

    NASA Astrophysics Data System (ADS)

    Pierson, William R.; Brachaczek, Wanda W.; Gorse, Robert A.; Japar, Steven M.; Norbeck, Joseph M.

    1986-03-01

    Nightly dew samples were collected on Allegheny Mountain in southwest Pennsylvania in August 1983. The dew was found to be acidic, with mean pH˜4.0. Free H+ comprised >80% of the total acidity, and the composition approximated an H2SO4/HNO3 mixture with average SO42-/NO3- mol ratio ˜1.3. The chemistry of the dew resembled that of rain at Allegheny, though the dew was generally more dilute. Atmospheric HNO3(g) was chiefly responsible for the dew NO3-. SO2 was the source of ˜80% of the dew SO42-. The allocation of dew H+ among atmospheric precursors was HNO3˜30%, SO2 ≥ 60%, aerosol H+ ≤ 10%. The most acidic dews were associated with wind from the west. Average deposition velocities (stated in centimeters per second) to dew were HNO3, 0.24; NO2, <0.02 SO2, ˜0.04; aerosol SO42-, ˜0.02; aerosol NH4+, 0.024; and aerosol species, 0.02-1. Comparison of the HNO3 deposition velocity with ten-fold higher summer daytime values reveals a pronounced diurnal variation. The 0.24 cm/s value for HNO3 may represent a maximum for any gas or submicron aerosol species whenever the atmosphere is strongly stable. Not all of the S(IV) in dew had been converted to SO42- by morning; thus the rate of oxidation must have been on a time scale of hours at nighttime ambient temperatures. In contrast, S(IV) in rain and fog samples was not evident. Deposition fluxes and cumulative deposition totals involving dew, rain, and settled fog water were compared. Rain proved by far the most important for deposition of all solute species, including acid.

  5. Acidity of vapor plume from cooling tower mixed with flue gases emitted from coal-fired power plant.

    PubMed

    Hlawiczka, Stanislaw; Korszun, Katarzyna; Fudala, Janina

    2016-06-01

    Acidity of products resulting from the reaction of flue gas components emitted from a coal-fired power plant with water contained in a vapor plume from a wet cooling tower was analyzed in a close vicinity of a power plant (710 m from the stack and 315 m from the cooling tower). Samples of this mixture were collected using a precipitation funnel where components of the mixed plumes were discharged from the atmosphere with the rainfall. To identify situations when the precipitation occurred at the same time as the wind directed the mixed vapor and flue gas plumes above the precipitation funnel, an ultrasound anemometer designed for 3D measurements of the wind field located near the funnel was used. Precipitation samples of extremely high acidity were identified - about 5% of samples collected during 12 months showed the acidity below pH=3 and the lowest recorded pH was 1.4. During the measurement period the value of pH characterizing the background acidity of the precipitation was about 6. The main outcome of this study was to demonstrate a very high, and so far completely underestimated, potential of occurrence of episodes of extremely acid depositions in the immediate vicinity of a coal-fired power plant. PMID:26950639

  6. Acidity of vapor plume from cooling tower mixed with flue gases emitted from coal-fired power plant.

    PubMed

    Hlawiczka, Stanislaw; Korszun, Katarzyna; Fudala, Janina

    2016-06-01

    Acidity of products resulting from the reaction of flue gas components emitted from a coal-fired power plant with water contained in a vapor plume from a wet cooling tower was analyzed in a close vicinity of a power plant (710 m from the stack and 315 m from the cooling tower). Samples of this mixture were collected using a precipitation funnel where components of the mixed plumes were discharged from the atmosphere with the rainfall. To identify situations when the precipitation occurred at the same time as the wind directed the mixed vapor and flue gas plumes above the precipitation funnel, an ultrasound anemometer designed for 3D measurements of the wind field located near the funnel was used. Precipitation samples of extremely high acidity were identified - about 5% of samples collected during 12 months showed the acidity below pH=3 and the lowest recorded pH was 1.4. During the measurement period the value of pH characterizing the background acidity of the precipitation was about 6. The main outcome of this study was to demonstrate a very high, and so far completely underestimated, potential of occurrence of episodes of extremely acid depositions in the immediate vicinity of a coal-fired power plant.

  7. Ground-based intercomparison of nitric acid measurement techniques

    NASA Astrophysics Data System (ADS)

    Fehsenfeld, Fred C.; Huey, L. Greg; Sueper, Donna T.; Norton, Richard B.; Williams, Eric J.; Eisele, Fred L.; Mauldin, R. Lee; Tanner, David J.

    1998-02-01

    An informal intercomparison of gas-phase nitric acid (HNO3) measuring techniques was carried out. The intercomparison involved two new chemical ionization mass spectrometers (CIMSs) that have been developed for the measurement of HNO3 along with an older, more established filter pack (FP) technique. The filter pack was composed of a teflon prefilter which collected aerosols followed by a nylon filter which collected the gas-phase HNO3. The study was carried out during the late winter and early spring of 1996 at a site located on the western edge of the Denver metropolitan area. Throughout the study the two CIMS techniques were in general agreement. However, under certain conditions the HNO3 levels obtained from the nylon filter of the FP gave values for the gas-phase concentration of HNO3 that were somewhat higher than that recorded by the two CIMS systems. The formation of ammonium nitrate (NH4NO3) containing aerosols is common during the colder months in this area. An analysis of these results suggests that the HNO3 collected by the nylon filter in the FP suffers an interference associated with the disproportionation of NH4NO3 from aerosols containing that compound that were initially collected on the teflon prefilter. This problem with the FP technique has been suggested from results obtained in previous intercomparisons.

  8. Vapor pressures and calculated heats of vaporization of concentrated nitric acid solutions in the composition range 71 to 89 percent nitrogen dioxide, 1 to 10 percent water, and in the temperature range 10 to 60 degrees C

    NASA Technical Reports Server (NTRS)

    Mckeown, A B; Belles, Frank E

    1954-01-01

    Total vapor pressures were measured for 16 acid mixtures of the ternary system nitric acid, nitrogen dioxide, and water within the temperature range 10 degrees to 60 degrees Celsius, and with the composition range 71 to 89 weight percent nitric acid, 7 to 20 weight percent nitrogen dioxide, and 1 to 10 weight percent water. Heats of vaporization were calculated from the vapor pressure measurements for each sample for the temperatures 25, 40, and 60 degrees Celsius. The ullage of the apparatus used for the measurements was 0.46. Ternary diagrams showing isobars as a function of composition of the system were constructed from experimental and interpolated data for the temperatures 25, 40, 45, and 60 degrees C and are presented herein.

  9. Ozone, nitric acid, and ammonia air pollution is unhealthy for people and ecosystems in southern Sierra Nevada, California.

    PubMed

    Cisneros, Ricardo; Bytnerowicz, Andrzej; Schweizer, Donald; Zhong, Sharon; Traina, Samuel; Bennett, Deborah H

    2010-10-01

    Two-week average concentrations of ozone (O3), nitric acid vapor (HNO3) and ammonia (NH3) were measured with passive samplers during the 2002 summer season across the central Sierra Nevada Mountains, California, along the San Joaquin River drainage. Elevated concentrations of the pollutants were determined with seasonal means for individual sites ranging between 62 and 88 ppb for O3, 1.0-3.8 microg m(-3) for HNO3, and 2.6-5.2 microg m(-3) for NH3. Calculated O3 exposure indices were very high, reaching SUM00-191 ppm h, SUM60-151 ppm h, and W126-124 ppm h. Calculated nitrogen (N) dry deposition ranged from 1.4 to 15 kg N ha(-1) for maximum values, and 0.4-8 kg N ha(-1) for minimum values; potentially exceeding Critical Loads (CL) for nutritional N. The U.S., California, and European 8 h O3 human health standards were exceeded during 104, 108, and 114 days respectively, indicating high risk to humans from ambient O3. PMID:20708832

  10. Nitric acid photolysis on surfaces in low-NOx environments: Significant atmospheric implications

    NASA Astrophysics Data System (ADS)

    Zhou, Xianliang; Gao, Honglian; He, Yi; Huang, Gu; Bertman, Steven B.; Civerolo, Kevin; Schwab, James

    2003-12-01

    Nitric acid (HNO3) is the dominant end product of NOx (= NO + NO2) oxidation in the troposphere, and its dry deposition is considered to be a major removal pathway for the atmospheric reactive nitrogen. Here we present both field and laboratory results to demonstrate that HNO3 deposited on ground and vegetation surfaces may undergo effective photolysis to form HONO and NOx, 1-2 orders of magnitude faster than in the gas phase and aqueous phase. With this enhanced rate, HNO3 photolysis on surfaces may significantly impact the chemistry of the overlying atmospheric boundary layer in remote low-NOx regions via the emission of HONO as a radical precursor and the recycling of HNO3 deposited on ground surfaces back to NOx.

  11. Vapor-pressure osmometric study of the molecular weight and aggregation tendency of a reference-soil fulvic acid

    USGS Publications Warehouse

    Marinsky, J.A.; Reddy, M.M.

    1990-01-01

    The molecular weight and aggregation tendency of a reference-soil fulvic acid in Armadale horizon Bh were determined by vapor-pressure osmometry using tetrahydrofuran and water as solvents. With tetrahydrofuran, number-average molecular weight values of 767 ?? 34 and 699 ?? 8 daltons were obtained from two separate sets of measurements. Two sets of measurements with water also yielded values within this range (754 ?? 70 daltons) provided that the fulvic acid concentration in water did not exceed 7 mg ml-1; at higher concentrations (9.1-13.7 mg ml-1) a number-average molecular weight of 956 ?? 25 daltons was resolved, providing evidence of molecular aggregation. Extension of these studies to 80% neutralized fulvic acid showed that a sizeable fraction of the sodium counter ion is not osmotically active.

  12. Vapor-phase esterification of acetic acid with ethanol catalyzed by a macroporous sulfonated styrene-divinylbenzene (20%) resin

    SciTech Connect

    Gimenez, J.; Costa, J.; Cervera, S.

    1987-02-01

    The kinetics of the vapor-phase (85-120/sup 0/C) esterification of acetic acid with ethyl alcohol, at atmospheric pressure, catalyzed by a macroporous sulfonated styrene-divinylbenzene (DVB;20%) resin, has been studied. A simple first-order model (r = kp/sub 1/) fits experimental kinetic data properly for a constant reactants ratio. Discussion by means of L-H-H-W models shows that the rate-controlling step is the surface reaction with a single-site mechanism. The apparent activation energy is 4000 cal/mol.

  13. Effects of nitric acid gas alone or in combination with ozone on healthy volunteers

    SciTech Connect

    Aris, R.; Christian, D.; Tager, I.; Ngo, L.; Finkbeiner, W.E.; Balmes, J.R. )

    1993-10-01

    Nitric acid (HNO3) is the most prevalent acid air pollutant in the western United States and has the potential to cause adverse respiratory effects through both acidification and oxidation reactions. To study this potential, we measured physiologic (specific airway resistance, SRaw, FEV1, and FVC) and bronchoalveolar lavage (total and differential cell counts, LDH, fibronectin, and total protein) end points in a group of 10 healthy, athletic subjects who were exposed to 500 micrograms/m3 of HNO3 gas or filtered air for 4 h during moderate exercise (ventilatory rate, 40 L/min) and underwent bronchoscopy 18 h later. Under an identical protocol, 10 healthy subjects were exposed to 500 micrograms/m3 of HNO3 gas plus 0.20 ppm ozone (O3) or 0.20 ppm O3 alone to determine if HNO3 might enhance the toxicity of O3. In addition to bronchoalveolar lavage (BAL), we employed the techniques of isolated left mainstem bronchial lavage and bronchial biopsy to determine if proximal airway injury was caused by pollutant exposure and whether there was any correlation with the degree of distal lung injury as assessed by BAL. We found no significant differences in pulmonary function tests or in the cellular or biochemical constituents in either the BAL or the left mainstem lavage fluids between the HNO3 and the air exposures. Similarly, there were no differences in these end points between the HNO3/O3 and the O3 exposures. Furthermore, there were no significant differences in the bronchial biopsy specimens between the HNO3 and air exposures or between the HNO3/O3 and O3 exposures.

  14. Does Nitric Acid Dissociate at the Aqueous Solution Surface?

    SciTech Connect

    Lewis, Tanza; Winter, Berndt; Stern, Abraham C.; Baer, Marcel D.; Mundy, Christopher J.; Tobias, Douglas J.; Hemminger, J. C.

    2011-11-03

    Nitric acid is a prevalent component of atmospheric aerosols, and the extent of nitric acid dissociation at aqueous interfaces is relevant to its role in heterogeneous atmospheric chemistry. Several experimental and theoretical studies have suggested that the extent of dissociation of nitric acid near aqueous interfaces is less than in bulk solution. Here, dissociation of HNO3 at the surface of aqueous nitric acid is quantified using X-ray photoelectron spectroscopy of the nitrogen local electronic structure. The relative amounts of undissociated HNO3(aq) and dissociated NO3-(aq) are identified by the distinguishable N1s core-level photoelectron spectra of the two species, and we determine the degree of dissociation, αint, in the interface (the first ~3 layers of solution) as a function of HNO3 concentration. Our measurements show that dissociation is decreased by approximately 20% near the solution interface compared with bulk, and furthermore that dissociation occurs even in the top-most solution layer. The experimental results are supported by first-principles MD simulations, which show that hydrogen-bonds between HNO3 and water molecules at the solution surface stabilize the molecular form at low concentration, in analogy to the stabilization of molecular HNO3 that occurs in bulk solution at high concentration. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE.

  15. Study of the liquid vapor equilibrium in the bromine-hydrobromic acid-water system

    NASA Technical Reports Server (NTRS)

    Benizri, R.; Lessart, P.; Courvoisier, P.

    1984-01-01

    A glass ebullioscope was built and at atmospheric pressure, liquid-vapor equilibria relative to the Br2-HBr-H2O system, in the concentration range of interest for evaluation of the Mark 13 cycle was studied. Measurements were performed for the brome-azeotrope (HBr-H2O) pseudo-binary system and for the ternary system at temperatures lower than 125 C and in the bromine concentration range up to 13% wt.

  16. Retrieval of atmospheric O(3), HNO(3), CFC-11, and CFC-12 profiles from MIPAS-B-89 limb emission spectra.

    PubMed

    Clarmann, T V; Oelhaf, H; Fischer, H

    1993-11-20

    During the night from May 17 to May 18, 1989, the first of four flights of the Michelson Interferometer for Passive Atmospheric Sounding, Balloon-borne version (MIPAS-B) instrument took place from the Centre National d'Etudes Spatiales balloon-launching site at Aire-sur-l'Adour (France, 44° N latitude). From approximately 33 km float altitude, stratospheric and tropospheric limb infrared emission spectra have been recorded by this novel type of fast-scanning interferometer. Although the measured spectra did not reach the expected quality and the a priori information on the corresponding viewing directions was coarse, the data were processed successfully with a retrieval algorithm specially adapted for application to noisydata. Mixingratio profiles of ozone, nitric acid, CFC-11, and CFC-12 havebeen retrieved from limb sequences of wide spectral intervals by nonlinear least-squares fitting in combination with a layer-bylayer onion-peeling approach. A rigorous error analysis has been carried out by means of Monte Carlo calculations.

  17. Effect the conditions of the acid-thermal modification of clinoptilolite have on the catalytic properties of palladium-copper complexes anchored on it in the reaction of carbon monoxide oxidation

    NASA Astrophysics Data System (ADS)

    Rakitskaya, T. L.; Kiose, T. A.; Ennan, A. A.; Golubchik, K. O.; Oleksenko, L. P.; Gerasiova, V. G.

    2016-06-01

    The dependence of the physicochemical and structural-adsorption properties of natural and acid-thermal modified clinoptilolite, and of Pd(II)-Cu(II) catalysts based on them, on the duration of acid-thermal modification is investigated. The samples under study are described via XRD and thermal gravimetric (DTG and DTA) analysis, IR, DR UV-Vis, EPR spectroscopy, and water vapor adsorption. Values of both the specific surface area ( S sp) and pH of aqueous suspensions are determined. The resulting catalysts are tested in the reaction of low-temperature carbon monoxide oxidation with air oxygen. A conclusion is drawn about the nature of surface bimetallic Pd(II)-Cu(II) complexes. The greatest catalytic activity is shown by complexes based on clinoptilolite and modified with 3 M HNO3 for 0.5 and 1 h.

  18. Energetic particle-induced enhancements of stratospheric nitric acid

    NASA Technical Reports Server (NTRS)

    Aikin, Arthur C.

    1994-01-01

    Inclusion of complete ion chemistry in the calculation of minor species production during energetic particle deposition events leads to significant enhancement in the calculated nitric acid concentration during precipitation. An ionization rate of 1.2 x 10(exp 3)/cu cm/s imposed for 1 day increases HNO3 from 3 x 10(exp 5) to 6 x 10(exp 7)/cu cm at 50 km. With an ionization rate of 600 cu cm/s, the maximum HNO3 is 3 x 10(exp 7)/cu cm. Calculations which neglect negative ions predict the nitric acid will fall during precipitation events. The decay time for converting HNO3 into odd nitrogen and hydrogen is more than 1 day for equinoctial periods at 70 deg latitude. Examination of nitric acid data should yield important information on the magnitude and frequency of charged particle events.

  19. Elusive Carbonic Acid: A Determination of its Vapor Pressures and Enthalpy of Sublimation for Mars and Beyond

    NASA Astrophysics Data System (ADS)

    Lewis, Ariel S.; Hudson, R. L.; Moore, M. H.; Cooper, P. D.

    2007-10-01

    Solid H2O and CO2 are present on Mars, some Galilean satellites, comets, and interstellar ices. Laboratory work on frozen H2O-CO2 mixtures shows that they produce H2CO3, carbonic acid, when exposed to either high-energy radiation (keV, MeV) or vacuum-UV photons (eV). While this molecule readily dissociates at 298 K, its stability below about 250 K suggests that it should exist in extraterrestrial environments. Unfortunately, little is known of solid-phase carbonic acid at temperatures relevant to planetary science. Recently we have studied some of the thermodynamic properties of carbonic acid. To synthesize this compound, we first injected a KHCO3 solution onto a substrate, pre-cooled to 15 K, to make a thin icy film. On top of this, an HBr solution was injected to make a second icy film. The substrate then was heated to about 200 K to initiate an acid-base reaction between KHCO3 and HBr, and to sublime the water present into a vacuum chamber. The resulting formation of carbonic acid was confirmed by recording infrared (IR) spectra of the samples before and after warming. The ices then were further heated to 240 - 255 K, and spectra recorded over time. Decreases in carbonic acid's IR bands near 1300 and 1500 cm-1 allowed the vapor pressure of the compound to be measured at several temperatures, from which an enthalpy of sublimation was determined. Comparisons were made to the heats of sublimation for formic and acetic acids, both those measured by us and those already in the literature. This work was supported by the Mars Fundamental Research Program and Goddard Center for Astrobiology. The first author was supported by an award from the Summer Undergraduate Internship in Astrobiology program.

  20. Thermodynamic Phase And Chemical Equilibrium At 0-110°C For The H+-K+-Na+-Cl--H2O System Up To 16 Molal And The HNO3-H2O System Up To 20 Molal Using An Association-Based Pitzer Model Compatible With ASPEN Plus

    SciTech Connect

    Todd T. Nichols; Dean D. Taylor

    2003-09-01

    A status is presented of the parameterization during FY2003 of an association-based Pitzer model to simulate chemical and phase equilibria of acid-chloride-nitrate-mercury aqueous electrolyte systems at 0-100° C within the industry-standard process simulator, ASPEN Plus. Compatibility with ASPEN Plus requires that the Pitzer model used be limited to the third virial coefficient and have the values of b and a1 as originally proposed by Pitzer. Two aqueous models for 0-110° C at atmospheric pressure were parameterized in FY03. The model for the aqueous H+-K+-Na+-Cl- system is applicable for 0-16 molal, and the HNO3-H2O for 0-20 molal. An association-based Pitzer activity coefficient model is combined with Henry.s law to predict activity/osmotic coefficient and VLE. The chloride model also predicts KCl and NaCl solubility, while the nitric acid model has the unique capability of predicting extent of dissociation with an average absolute deviation of 1.43%. The association-based approach presented here extends the utility of the molality-based Pitzer model past 6 molal to predict activity/osmotic coefficients up to 16-20 molal. The association-based approach offers the additional benefits of predicting extent of dissociation and of allowing the Pitzer model to be fully utilized in commercial simulators, such as ASPEN Plus, that require accounting for association to implement Henry’s law. The Pitzer models presented here provide the chemical process simulation engineer with a superior alternative to the Electrolyte NRTL model that can easily be used in ASPEN Plus.

  1. Thermodynamic Phase And Chemical Equilibrium At 0-110 C For The H+-K+-Na+-Cl--H2O System Up To 16 Molal And The HNO3-H2O System Up To 20 Molal Using An Association-Based Pitzer Model Compatible With ASPEN Plus

    SciTech Connect

    Nichols,T.T.; Taylor,D.D.

    2003-09-26

    A status is presented of the parameterization during FY2003 of an association-based Pitzer model to simulate chemical and phase equilibria of acid-chloride-nitrate-mercury aqueous electrolyte systems at 0-100 C within the industry-standard process simulator, ASPEN Plus. Compatibility with ASPEN Plus requires that the Pitzer model used be limited to the third virial coefficient and have the values of b and a1 as originally proposed by Pitzer. Two aqueous models for 0-110 C at atmospheric pressure were parameterized in FY03. The model for the aqueous H+-K+-Na+-Cl- system is applicable for 0-16 molal, and the HNO3-H2O for 0-20 molal. An association-based Pitzer activity coefficient model is combined with Henry's law to predict activity/osmotic coefficient and VLE. The chloride model also predicts KCl and NaCl solubility, while the nitric acid model has the unique capability of predicting extent of dissociation with an average absolute deviation of 1.43%. The association-based approach presented here extends the utility of the molality-based Pitzer model past 6 molal to predict activity/osmotic coefficients up to 16-20 molal. The association-based approach offers the additional benefits of predicting extent of dissociation and of allowing the Pitzer model to be fully utilized in commercial simulators, such as ASPEN Plus, that require accounting for association to implement Henry's law. The Pitzer models presented here provide the chemical process simulation engineer with a superior alternative to the Electrolyte NRTL model that can easily be used in ASPEN Plus.

  2. Absorption cross section for the 5νOH stretch of acetic acid and peracetic acid

    NASA Astrophysics Data System (ADS)

    Begashaw, I. G.; Collingwood, M.; Bililign, S.

    2009-12-01

    We report measurements of the absorption cross sections for the vibrational O-H stretch (5νOH) overtone transitions in glacial acetic acid and peracetic acid. The photochemistry that results from overtone excitation has been shown to lead to OH radical production in molecules containing O-H (HNO3, H2O2). In addition the overtone excitation has been observed to result in light initiated chemical reaction. A Cavity ring-down spectroscopy (CRDS) instrument comprising of an Nd:YAG pumped dye laser and 620nm high reflectivity mirrors (R=99.995%) was used to measure the cross sections. The dye laser wavelength was calibrated using water vapor spectrum and the HITRAN 2008 database. The instrument’s minimum detectable absorption is αmin =4.5 *10-9cm-1 Hz-1/2 at 2σ noise level near the peak of the absorption feature. This measurement is the first for acetic acid at this excitation level. Preliminary results for acetic acid show the peak occurs near 615nm. Procedures for separating the monomer and dimer contribution will be presented. We would like to acknowledge support from NSF award #0803016 and NOAA-EPP award #NA06OAR4810187.

  3. Collection of VLE data for acid gas---alkanolamine systems using fourier transform infrared spectroscopy. [Vapor-liquid equilibrium

    SciTech Connect

    Bullin, J.A.; Frazier, R.E.

    1992-01-01

    The industrial standard process for the purification of natural gas is to remove acid gases, mainly hydrogen sulfide and carbon dioxide, by the absorption and reaction of these gases with alkanolamines. Inadequate data for vapor--liquid equilibrium (VLE) hinder the industry from converting operations to more energy efficient amine mixtures and conserving energy. Some energy reductions have been realized in the past decade by applying such amine systems as hindered'' amines, methyldiethanolamine (MDEA), and MDEA based amine mixtures. However, the lack of reliable and accurate fundamental VLE data impedes the commercial application of these more efficient alkanolamine systems. The first project objective is to improve the accuracy of vapor--liquid equilibrium measurements at low hydrogen sulfide concentrations. The second project objective is to measure the VLE for amine mixtures. By improving the accuracy of the VLE measurements on MDEA and mixtures with other amines, energy saving can be quickly and confidently implemented in the many existing absorption units already in use. If about 25% of the existing 95.3 billion SCFD gas purification capacity is converted to these new amine systems, the energy savings are estimated to be about 3 [times] 10[sup 14] BTU/yr.

  4. a Microwave and AB Initio Study of the Nitric Acid - Trimethylamine Complex

    NASA Astrophysics Data System (ADS)

    Sedo, Galen; Leopold, Kenneth R.

    2009-06-01

    The microwave spectrum of the gas phase nitric acid - trimethylamine complex has been observed using Fourier transform microwave spectroscopy. The experimental rotational constants and (CH{_3}){_3}{^1}{^5}N-HNO{_3} isotope shifts are consistent with a complex in which the nitric acid proton forms a hydrogen bond to the nitrogen of the amine, similar to the experimentally determined structure of H{_3}N-HNO{_3} Analysis of the hyperfine structure in both the parent and (CH{_3}){_3}{^1}{^5}N-HNO{_3} spectra made it possible to determine, unambiguously, the quadrupole coupling constants of the {^1}{^5}N nuclei in both the nitric acid and trimethylamine moieties. Ab initio calculations, using the MP2/6-311++G(2df,2pd) level of theory and basis set, have been performed and are in quantitative agreement with the available experimental data. Both the experimentally determined quadrupole coupling constants and the ab initio structure have been used to assess the degree of proton transfer occurring in the nitric acid - trimethylamine complex. These results will be compared to those obtained for the H{_3}N-HNO{_3} and HNO{_3}-(H{_2}O){_n} [n = 0 - 3] complexes and discussed in terms of how binding partner basicity and the number of solvent molecules influence the incipient ionization of nitric acid moiety. M. E. Ott, and K. R. Leopold, J. Phys. Chem. A 1999, 103,1322-1328.

  5. Determination of Activity Coefficients of di-(2-ethylhexyl) Phosphoric Acid Dimer in Select Organic Solvents Using Vapor Phase Osmometry

    SciTech Connect

    Michael F. Gray; Peter Zalupski; Mikael Nilsson

    2013-08-01

    Effective models for solvent extraction require accurate characterization of the nonideality effects for each component, including the extractants. In this study, the nonideal behavior of the industrial extractant di(2-ethylhexyl) phosphoric acid has been investigated using vapor pressure osmometry (VPO). From the osmometry data, activity coefficients for the HDEHP dimer were obtained based on a formulation of the regular solution theory of Scatchard and Hildebrand, and the Margules two- and three-suffix equations. The results show similarity with a slope-analysis based relation from previous literature, although important differences are highlighted. The work points towards VPO as a useful technique for this type of study, but care must be taken with the choice of standard and method of analysis.

  6. Competition between Displacement and Dissociation of a Strong Acid Compared to a Weak Acid Adsorbed on Silica Particle Surfaces: The Role of Adsorbed Water.

    PubMed

    Fang, Yuan; Tang, Mingjin; Grassian, Vicki H

    2016-06-16

    The adsorption of nitric (HNO3) and formic (HCOOH) acids on silica particle surfaces and the effect of adsorbed water have been investigated at 296 K using transmission FTIR spectroscopy. Under dry conditions, both nitric and formic acids adsorb reversibly on silica. Additionally, the FTIR spectra show that both of these molecules remain in the protonated form. At elevated relative humidities (RH), adsorbed water competes both for surface adsorption sites with these acids as well as promotes their dissociation to hydronium ions and the corresponding anions. Compared to HNO3, the extent of dissociation is much smaller for HCOOH, very likely because it is a weaker acid. This study provides valuable insights into the interaction of HNO3 and HCOOH with silica surface on the molecular level and further reveals the complex roles of surface-adsorbed water in atmospheric heterogeneous chemistry of mineral dust particles-many of these containing silica.

  7. Competition between Displacement and Dissociation of a Strong Acid Compared to a Weak Acid Adsorbed on Silica Particle Surfaces: The Role of Adsorbed Water.

    PubMed

    Fang, Yuan; Tang, Mingjin; Grassian, Vicki H

    2016-06-16

    The adsorption of nitric (HNO3) and formic (HCOOH) acids on silica particle surfaces and the effect of adsorbed water have been investigated at 296 K using transmission FTIR spectroscopy. Under dry conditions, both nitric and formic acids adsorb reversibly on silica. Additionally, the FTIR spectra show that both of these molecules remain in the protonated form. At elevated relative humidities (RH), adsorbed water competes both for surface adsorption sites with these acids as well as promotes their dissociation to hydronium ions and the corresponding anions. Compared to HNO3, the extent of dissociation is much smaller for HCOOH, very likely because it is a weaker acid. This study provides valuable insights into the interaction of HNO3 and HCOOH with silica surface on the molecular level and further reveals the complex roles of surface-adsorbed water in atmospheric heterogeneous chemistry of mineral dust particles-many of these containing silica. PMID:27220375

  8. Determination of Water Vapor Pressure Over Corrosive Chemicals Versus Temperature Using Raman Spectroscopy as Exemplified with 85.5% Phosphoric Acid.

    PubMed

    Rodier, Marion; Li, Qingfeng; Berg, Rolf Willestofte; Bjerrum, Niels Janniksen

    2016-07-01

    A method to determine the water vapor pressure over a corrosive substance was developed and tested with 85.5 ± 0.4% phosphoric acid. The water vapor pressure was obtained at a range of temperatures from ∼25 ℃ to ∼200 ℃ using Raman spectrometry. The acid was placed in an ampoule and sealed with a reference gas (either hydrogen or methane) at a known pressure (typically ∼0.5 bar). By comparing the Raman signals from the water vapor and the references, the water pressure was determined as a function of temperature. A considerable amount of data on the vapor pressure of phosphoric acid are available in the literature, to which our results could successfully be compared. A record value of the vapor pressure, 3.40 bar, was determined at 210 ℃. The method required a determination of the precise Raman scattering ratios between the substance, water, and the used reference gas, hydrogen or methane. In our case the scattering ratios between water and reference ν1 Q-branches were found to be 1.20 ± 0.03 and 0.40 ± 0.02 for H2 and CH4, respectively.

  9. Determination of Water Vapor Pressure Over Corrosive Chemicals Versus Temperature Using Raman Spectroscopy as Exemplified with 85.5% Phosphoric Acid.

    PubMed

    Rodier, Marion; Li, Qingfeng; Berg, Rolf Willestofte; Bjerrum, Niels Janniksen

    2016-07-01

    A method to determine the water vapor pressure over a corrosive substance was developed and tested with 85.5 ± 0.4% phosphoric acid. The water vapor pressure was obtained at a range of temperatures from ∼25 ℃ to ∼200 ℃ using Raman spectrometry. The acid was placed in an ampoule and sealed with a reference gas (either hydrogen or methane) at a known pressure (typically ∼0.5 bar). By comparing the Raman signals from the water vapor and the references, the water pressure was determined as a function of temperature. A considerable amount of data on the vapor pressure of phosphoric acid are available in the literature, to which our results could successfully be compared. A record value of the vapor pressure, 3.40 bar, was determined at 210 ℃. The method required a determination of the precise Raman scattering ratios between the substance, water, and the used reference gas, hydrogen or methane. In our case the scattering ratios between water and reference ν1 Q-branches were found to be 1.20 ± 0.03 and 0.40 ± 0.02 for H2 and CH4, respectively. PMID:27273974

  10. Electrical conductivity measurements of aqueous boric acid at 25--350{degree}C at saturation vapor pressure. Final report

    SciTech Connect

    Ho, P.C.; Palmer, D.A.

    1995-09-01

    Electrical conductance measurements of aqueous boric acid solutions (15-110 g/kg-H{sub 2}O {equivalent_to} 0.251--1.815 mol/kg-H{sub 2}O) were measured over the temperature range 25 to 75 C at saturation vapor pressures in glass cells with parallel platinum electrodes. Sixteen series of measurements were made involving three samples of boric acid from different sources. Conductance measurements were also made at 15.5 and 30.5 g/kg-H{sub 2}O over the temperature range 100 to 350 C at 50 C intervals with a metallic cell fitted with concentric platinum electrodes. The specific conductances of H{sub 3}BO{sub 3} (aq)were calculated after correction for the conductance of the solvent (water) and are tabulated in this report. At the specific conditions requested in the project description, namely a concentration of 110 g/kg-H{sub 2}O and 65 C, the specific conductance of boric acid is 293.2 {+-} 1.8 microSiemens/cm based on duplicate measurements of four independent solutions. The results from these tests will be utilized by the Tokamak Physics Experimental Project (TPX).

  11. C3HNO 3-Oxo-2-propenenitrile

    NASA Astrophysics Data System (ADS)

    Demaison, J.

    This document is part of Part 2 of Subvolume D 'Asymmetric Top Molecules' of Volume 29 'Molecular Constants Mostly from Microwave, Molecular Beam, and Sub-Doppler Laser Spectroscopy' of Landolt-Börnstein - Group II 'Molecules and Radicals'.

  12. Hydrofluoric and nitric acid transport through lipid bilayer membranes.

    PubMed

    Gutknecht, J; Walter, A

    1981-06-01

    Hydrofluoric and nitric acid transport through lipid bilayer membranes were studied by a combination of electrical conductance and pH electrode techniques. Transport occurs primarily by nonionic diffusion of molecular HF and HNO3. Membrane permeabilities to HF and HNO3 ranged from 10(-4) to 10(-3) cm . s-1, five to seven orders of magnitude higher than the permeabilities to NO-3, F- and H+. Our results are consistent with the hypothesis that F- transport through biological membranes occurs mainly by nonionic diffusion of HF. Our results also suggest that of the two principal components of 'acid rain', HNO3 may be more toxic than H2SO4.

  13. Direct ab initio dynamics calculations for rates and the kinetic isotope effects of multiproton transfer in ClONO2 + HCl --> HNO3 + Cl2 reactions with water clusters: breakdown of the rule of the geometric mean.

    PubMed

    Nam, Kikyung; Kim, Yongho

    2009-04-14

    We performed high-level quantum mechanical calculations and direct ab initio reaction dynamics calculations for multiple proton transfers in ClONO(2)+HCl-->HNO(3)+Cl(2) with water clusters containing one to two water molecules, which can be used as a model of the reactions occurring on ice surface in stratospheric clouds. The energy barriers of these reactions depend on the number of water molecules involved. Two and three protons in these reactions with one and two water molecules, respectively, were transferred concertedly and asynchronously. The potential energy barrier at the MP2/6-311++(3df,3pd)//MP2/6-31G(d,p) level was 4.8 kcal/mol for the triple proton transfer involving two water molecules with a rate constant of 1.6x10(3) s(-1) at 197 K. The potential energy curve near the saddle points was very flat and the tunneling effect on the proton transfer was negligible. The primary HH/DH kinetic isotope effect for the double proton transfer involving one water molecule was lower than unity due to the enhanced force constant at the transition state. The rule of the geometric mean for the concerted proton transfer does not hold in these reactions because the zero-point energy changes of each proton in flight at the transition state are not the same in the highly asynchronous processes.

  14. Heterogeneous interactions of chlorine nitrate, hydrogen chloride, and nitric acid with sulfuric acid surfaces at stratospheric temperatures

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Rossi, Michel J.; Golden, David M.

    1988-01-01

    The heterogeneous interactions of ClONO2, HCl, and HNO3 with sulfuric acid surfaces were studied using a Knudsen cell flow reactor. The surfaces studied, chosen to simulate global stratospheric particulate, were composed of 65-75 percent H2SO4 solutions at temperatures in the range -63 to -43 C. Heterogeneous loss, but not reaction, of HNO3 and HCl occurred on these surfaces; the measured sticking coefficients are reported. Chlorine nitrate reacted on the cold sulfuric acid surfaces, producing gas-phase HOCl and condensed HNO3. CLONO2 also reacted with HCl dissolved in the 65-percent H2SO4 solution at -63 C, forming gaseous Cl2. In all cases studied, the sticking and/or reaction coefficients were much larger for the 65-percent H2SO4 solution at -63 C than for the 75-percent solution at -43 C.

  15. Depth profiling of ultra trace metal impurities in polytetrafluoroethylene wares by surface scraping and acid-vapor extraction followed by ICP-MS analysis.

    PubMed

    Tanaka, Masafumi; Takahashi, Makoto

    2002-10-01

    This paper describes the development of the depth profiling method of ultra trace metal impurities in polytetrafluoroethylene (PTFE) wares based on contamination-free sampling followed by acid-vapor extraction and its application to evaluate the washing method for PTFE wares. A contamination-free sampling process was achieved by scraping the surface of PTFE wares with the cleft face of a silicon wafer followed by exposing the PTFE scraped to highly pure acid-vapor. The concentration of metal impurities in extractants was determined by ICP-MS equipped with an electrothermal vaporizer (ETV-ICP-MS). The blank values of Al, Cr, Fe, Ni and Cu by the depth profiling method were 0.006, 0.004, 0.005, 0.002 and 0.003 ng, respectively. By analyzing the depth profile of beakers, the distributions of ultra trace (ng g(-1) level) metal impurities were clarified. An examination of the washing methods by the depth profiling method also clarified that exposing to acid-vapor was more effective than the acid-dipping method for the elimination of metal impurities.

  16. Kinetics and mechanism of the thermooxidate destruction of polybutadiene rubber in perchloric acid vapor

    SciTech Connect

    Didikin, B.P.; Korobeinchev, O.P.; Orlov, V.N.

    1983-11-01

    This article examines the interaction of perchloric acid with films of polymer. The thermooxidative destruction of polybutadiene rubber was investigated with an apparatus which included a reactor with systems for dispensing the perchloric acid and inert diluent (argon) and for moving the rubber specimen in vacuum, a quartz microprobe joined to the ion source of a time-of-flight mass spectrometer, and a system for recording the mass spectra, temperature, and pressure. Topics considered include the time dependence of the rates of formation of HC1, CO, O/sub 2/, CO/sub 2/, and H/sub 2/O; the effects of perchloric acid partial pressure on the reaction rate; the effects of rubber film thickness on the reaction rate; the effects of temperature on the reaction rate; the effects of the Fe/sub 2/O/sub 3/ catalyst on the reaction rate; and the application of the kinetic data to analyzing the pyrolysis of mixed systems. The rubber reaction rate was determined from the degree of conversion of the perchloric acid, which is related to that of the rubber.

  17. Delayed production of sulfuric acid condensation nuclei in the polar stratosphere from El Chichon volcanic vapors

    NASA Technical Reports Server (NTRS)

    Hofmann, D. J.; Rosen, J. M.; Gringel, W.

    1985-01-01

    It is pointed out that measurements of the vertical profiles of atmospheric condensation nuclei (CN) have been conducted since 1973. Studies with a new instrument revealed that the CN concentration undergoes a remarkable annual variation in the 30-km region characterized by a large increase in the late winter/early spring period with a subsequent decay during the remainder of the year. The event particles are observed to be volatile at 150 C, suggesting a sulfuric acid-water composition similar to that found in the normal 20 km aerosol layer. The development of about 10 to the 7th metric tons of sulfuric acid aerosol following the injection of sulfurous gases by El Chichon in April 1982, prompted Hofmann and Rosen (1983) to predict a very large CN event for 1983. The present investigation is concerned with the actual observation of the predicted event. Attention is given to the observation of a very large increase of what appear to be small sulfuric acid droplets at 30-km altitude in January 1983 over Laramie, WY, in January 1983.

  18. LC50 values for rats acutely exposed to vapors of acrylic and methacrylic acid esters

    SciTech Connect

    Oberly, R.; Tansy, M.F.

    1985-01-01

    Acute exposure studies were conducted using adult male Sprague-Dawley rats to obtain LC50/24 concentrations for the common esters of acrylic and methacrylic acids. The order of acute toxicity was determined to be methyl acrylate > ethyl acrylate > butyl acrylate > butyl methacrylate > methyl methacrylate > ethyl methacrylate. Four-hour daily exposures (excluding weekends) of young adult male rats to 110 ppm methyl acrylate in air over a period of 32 d failed to produce significant differences in body or tissue weights, blood chemistries, gross metabolic performance, and spontaneous small-intestinal motor activities when compared with a sham-exposed group.

  19. A molal-based model for strong acid chemistry at low temperatures (<200 to 298 K)

    NASA Astrophysics Data System (ADS)

    Marion, Giles M.

    2002-07-01

    Geochemical processes occurring in cold environments on Earth, Mars, and Europa have elicited considerable interest in the application of geochemical models to subzero temperatures. Few existing geochemical models explicitly include acid chemistry and those that do are largely restricted to temperatures ≥0°C or rely on the mole-fraction scale rather than the more common molal scale. This paper describes (1) use of the Clegg mole-fraction acid models to develop a molal-based model for hydrochloric, nitric, and sulfuric acids at low temperatures; (2) incorporation of acid chemistry and nitrate minerals into the FREZCHEM model; (3) validation and limitations of the derived acid model; and (4) simulation of hypothetical acidic brines for Europa. The Clegg mole-fraction acid models were used to estimate activities of water and mean ionic activity coefficients that serve as the database for estimating molal Pitzer-equation parameters for HCl (188 to 298 K), HNO 3 (228 to 298 K), and H 2SO 4 (208 to 298 K). Model eutectics for HNO 3 and H 2SO 4 agree with experimental measurements to within ± 0.2°C. In agreement with previous work, the experimental freezing point depression (fpd) data for pure HCl at subzero temperatures were judged to be flawed and unreliable. Three alternatives are discussed for handling HCl chemistry at subzero temperatures. In addition to defining the solubility of solid-phase acids, this work also adds three new nitrate minerals and six new acid salts to the FREZCHEM model and refines equilibria among water ice, liquid water, and water vapor over the temperature range from 180 to 298 K. The final system is parameterized for Na-K-Mg-Ca-H-Cl-SO 4-NO 3-OH-HCO 3-CO 3-CO 2-H 2O. Simulations of hypothetical MgSO 4-H 2SO 4-H 2O and Na 2SO 4-MgSO 4-H 2SO 4-H 2O brines for Europa demonstrate how freezing can convert a predominantly salt solution into a predominantly acid solution at subzero temperatures. This result has consequences for the effects of

  20. Chemical relaxation of H bonds in formic acid vapor studied by resonant photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Winkler, A.; Mehl, J. B.; Hess, P.

    1994-02-01

    The chemical relaxation of hydrogen bonds in dimeric formic acid (methanoic acid) was studied in the gas phase by means of precise measurement of the speed of sound and the sound absorption as functions of the pressure and the temperature by exciting standing acoustic waves. The first radial acoustic resonance of a cylindrical cavity was excited by a modulated CO2 laser beam. Resonance profiles were measured and recorded by a computer-controlled system. Due to the high information content of this method, a consistent set of thermodynamic and kinetic parameters can be obtained. The equilibrium constants of the dimer/monomer and the cis-/trans-monomer equilibrium, the dissociation rate constant of (HCOOH)2 and the mean relaxation time of the vibrational states of the monomer-dimer mixture were determined by fitting a detailed theoretical model of the resonator to the measured values for the resonance frequency and the resonance broadening for total pressures in the range from 0.3 to 50 mbar and temperatures from 290 to 325 K. We obtained 159±2 J/(mol K) for the entropy and 61.8±0.5 kJ/mol for the enthalpy of dissociation at 300 K. We inferred a value for the enthalpy of isomerization of 10±5 kJ/mol. For the first time the pressure dependence of the dissociation rate constant was determined. It was found that the unimolecular decay is in the second-order regime at these low pressures as expected. The mean collision efficiency for the dissociation process relative to the dimer was obtained for HCOOH, He, and Ar to be 0.5±0.2, 0.05±0.02, and 0.08±0.02, respectively, independent of the temperature. We measured an average (pτ) value of 10±2 ns bar for the relaxation of the vibrational degrees of freedom. The activation energy of the dissociation of dimeric formic acid was determined to be 33±1 kJ/mol.

  1. Laboratory measurements of the microwave opacity and vapor pressure of sulfuric acid vapor under simulated conditions for the middle atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1985-01-01

    Microwave absorption measurements at wavelengths of 13.4 and 3.6 cm were made in gaseous H2SO4 in a CO2 atmosphere under simulated conditions for the Venus middle atmosphere. The results suggest that abundances of gaseous H2SO4 on the order of 15-30 ppm could account for the absorption observed by radio occultation measurements at these wavelengths. They also imply that such abundances would correspond to saturation vapor pressure existing at or above the 46-48-km range, which correlates with the observed cloud base.

  2. Deposition kinetics and characterization of stable ionomers from hexamethyldisiloxane and methacrylic acid by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Urstöger, Georg; Resel, Roland; Koller, Georg; Coclite, Anna Maria

    2016-04-01

    A novel ionomer of hexamethyldisiloxane and methacrylic acid was synthesized by plasma enhanced chemical vapor deposition (PECVD). The PECVD process, being solventless, allows mixing of monomers with very different solubilities, and for polymers formed at high deposition rates and with high structural stability (due to the high number of cross-links and covalent bonding to the substrate) to be obtained. A kinetic study over a large set of parameters was run with the aim of determining the optimal conditions for high stability and proton conductivity of the polymer layer. Copolymers with good stability over 6 months' time in air and water were obtained, as demonstrated by ellipsometry, X-Ray reflectivity, and FT-IR spectroscopy. Stable coatings showed also proton conductivity as high as 1.1 ± 0.1 mS cm-1. Chemical analysis showed that due to the high molecular weight of the chosen precursors, it was possible to keep the plasma energy-input-per-mass low. This allowed limited precursor fragmentation and the functional groups of both monomers to be retained during the plasma polymerization.

  3. Photo-induced cold vapor generation with low molecular weight alcohol, aldehyde, or carboxylic acid for atomic fluorescence spectrometric determination of mercury.

    PubMed

    Han, Chunfang; Zheng, Chengbin; Wang, Jun; Cheng, Guanglei; Lv, Yi; Hou, Xiandeng

    2007-06-01

    With UV irradiation, Hg(2+) in aqueous solution can be converted into Hg(0) cold vapor by low molecular weight alcohols, aldehydes, or carboxylic acids, e.g., methanol, formaldehyde, acetaldehyde, glycol, 1,2-propanediol, glycerol, acetic acid, oxalic acid, or malonic acid. It was found that the presence of nano-TiO(2) more or less improved the efficiency of the photo-induced chemical/cold vapor generation (photo-CVG) with most of the organic reductants. The nano-TiO(2)-enhanced photo-CVG systems can be coupled to various analytical atomic spectrometric techniques for the determination of ultratrace mercury. In this work, we evaluated the application of this method to the atomic fluorescence spectrometric (AFS) determination of mercury in cold vapor mode. Under the optimized experimental conditions, the instrumental limits of detection (based on three times the standard deviation of 11 measurements of a blank solution) were around 0.02-0.04 microg L(-1), with linear dynamic ranges up to 15 microg L(-1). The interference of transition metals and the mechanism of the photo-CVG are briefly discussed. Real sample analysis using the photo-CVG-AFS method revealed that it was promising for water and geological analysis of ultralow levels of mercury.

  4. Nitric acid and ammonia emissions from a mid-latitude prescribed wetlands fire

    NASA Astrophysics Data System (ADS)

    LeBel, P. J.; Cofer, W. R., III; Levine, J. S.; Vay, S. A.; Roberts, P. D.

    1988-08-01

    We have obtained the first simultaneous measurements of gaseous nitric acid (HNO3) and ammonia (NH3) in the smoke plume of a wetlands biomass burn. These measurements were made using tungsten oxide-coated diffusion denuder tubes from a helicopter during a prescribed burn at the Merritt Island National Wildlife Refuge, located at the NASA John F. Kennedy Space Center, Florida, on November 9, 1987. The mean NH3 and HNO3 mixing ratios measured in the smoke plume were 19 ppbv and 14 ppbv, respectively, both significantly higher than background mixing ratios. Nitric acid correlated well with carbon dioxide (CO2) produced by the combustion. The mean CO2-normalized emission ratio for HNO3 was found to be 1.2 × 10-4. Ammonia, however, did not correlate well with CO2 suggesting a more complex relationship between combustion and production/release of NH3.

  5. Rational Design of a Nile Red/Polymer Composite Film for Fluorescence Sensing of Organophosphonate Vapors using Hydrogen Bond Acidic Polymers

    SciTech Connect

    Levitsky, Igor; Krivoshlykov, Sergei G.; Grate, Jay W. )

    2000-12-01

    The solvatochromic dye Nile Red dispersed in selected hydrogen-bond acidic polymer matrices demonstrated strong fluorescence enhancement at the presence of dimethyl methylphosphonate (DMMP) vapors. Two hydrogen bond acidic polymers were examined as dye matrices, one with fluorinated alcohol groups on a polystyrene backbone (PSFA), and the other with fluorinated bisphenol groups alternating with oligodimethylsiloxane segments (BSP3). The combination of hydrogen-bond acidic polymer (a strong sorbent for DMMP) with the solvatochromic dye led to initial depression of the dye fluorescence and a significant red shift in the absorbance and fluorescence spectra. DMMP sorption changed the dye environment and dramatically altered the fluorescence spectrum and intensity, resulting in a strong fluorescence enhancement. It is proposed that this fluorescence enhancement is due to the competition set up between the dye and the sorbed vapor for polymeric hydrogen bonding sites. The highest responses were obtained with BSP3. DMMP detection has been demonstrated at sub-ppm DMMP concentrations, indicating very low detection limits compared to previous Nile Red/polymer matrix fluorescence vapor sensors. Nile Red/poly(methyl methacrylate) films prepared for comparisons exhibited substantially lower response to DMMP. Rational selection of polymers providing high sorption for DMMP and competition for hydrogen-bonding interactions with Nile Red yielded fluorescent films with high sensitivity.

  6. Development of the detection threshold concept from a close look at sorption occurrence inside a glass vial based on the in-vial vaporization of semivolatile fatty acids.

    PubMed

    Kim, Yong-Hyun; Kim, Ki-Hyun; Szulejko, Jan E; Parker, David

    2014-07-01

    Headspace (HS) analysis has been recommended as one of the most optimal methods for extracting and analyzing volatile organic compounds from samples in diverse media such as soil and water. Short-chain volatile fatty acids (VFA, C3-C7) with strong adsorptivity were selected as the target compounds to assess the basic characteristics of the HS analysis through simulation of HS conditions by in-vial vaporization of liquid-phase standards (VL) in 25 mL glass vials. The reliability of the VL approach was assessed by apportioning the in-vial VFA mass into three classes: (1) vaporized fraction, (2) dynamic adsorption on the vial walls (intermediate stage between vaporization and irreversible absorption), and (3) irreversible absorptive loss (on the vial wall). The dynamic adsorption partitioning inside the vial increased with n-VFA carbon number, e.g., 43% (C2: acetic acid, extrapolated value), 65% (C3: propanoic acid), and 98% (C7: heptanoic acid). The maximum irreversible losses for the studied n-VFAs exhibited a quadratic relationship with carbon number. If the detection threshold limit (DTL: the onset of mass detection after attaining the maximum irreversible loss) is estimated, the DTL values for target VFAs were in the range of 101 ng for i-valeric acid to 616 ng for propionic acid, which are larger than the method detection limit by about 3 orders of magnitude. Consequently, quantitation of VFAs using the VL approach should be critically assessed by simultaneously considering the DTL criterion and the initial VFA masses loaded into the vial.

  7. VAPOR VALVE

    DOEpatents

    Wouters, L.F.

    1959-08-25

    Electromagnetically operated vapor valves are described for apparatus employed in the separation of isotopes or elements to control the flow of gaseous vapors between a vaporizing charge chamber and an ionizing chamber, The charge chamber and ionizing chamber are positioned in a magnetic field, and the flow of vapors through an orifice connecting the chambers is regulated by regulating the flow of current through a resilient metal strip rigidly mounted at one end and positioned in the magnetic field adjacent to the orifice.

  8. Surface morphology study of Zr-based amorphous alloys after immersion in boiling nitric acid medium

    NASA Astrophysics Data System (ADS)

    Sharma, Poonam; Dhawan, Anil; Sharma, S. K.

    2016-05-01

    Weight loss studies have been performed to determine the corrosion resistance of amorphous Zr60Nb2Al10Ni8Cu20 and Zr59Nb3Al10Ni8Cu20 alloys in aqueous HNO3 media at boiling temperature. The FESEM micrographs has been obtained to know the surface morphology of specimens after immersion in 11.5M boiling aqueous HNO3 media. Zr59Nb3Al10Ni8Cu20 alloy shows better corrosion resistance in nitric acid media than Zr60Nb2Al10Ni8Cu20 alloy.

  9. The relationship between airborne acidity and ammonia in indoor environments.

    PubMed

    Suh, H H; Koutrakis, P; Spengler, J D

    1994-01-01

    Indoor acid aerosol, nitric acid (HNO3), and ammonia (NH3) concentrations were measured in 47 homes in State College, Pennsylvania, during the summer of 1991. From each home, 12-hour indoor, 12- and 24-hour outdoor, and 12-hour air exchange samples were collected continuously over a 5-day period. Additionally, questionnaires were administered daily by field technicians to obtain information on house occupant number, ventilation, gas stove use, pets, and other housing characteristics. In this paper, we discuss the relationship between NH3 and corresponding concentrations of aerosol strong acidity (H+) and HNO3 inside these homes. As part of this analysis, we also examined indoor/outdoor concentration relationships and identified housing factors that may influence indoor levels. In State College, indoor NH3 concentrations were higher than corresponding outdoor levels, with air conditioner use, air exchange rates, and occupant number identified as important determinants of indoor levels. Indoor concentrations of both H+ and HNO3 were substantially lower than outdoor levels, as homes with air exchange rates less than one exchange per hour were found to have essentially no acid indoors. These low H+ and HNO3 levels likely resulted from their reaction with indoor NH3 and with indoor surfaces. Indoor NH3 concentrations were higher than outdoor levels, indicating the presence of indoor NH3 sources; however, correlations between indoor NH3 and both pets and occupants, its primary indoor sources, were weak and negative, respectively. Mass balance models that included an NH3 neutralization term were found to predict indoor H+ concentrations reasonably well, representing a substantial improvement over outdoor concentrations alone. The accumulation of NH3 indoors was found to be the primary determinant of indoor H+ and HNO3 levels.

  10. Direct Real-Time Detection of Vapors from Explosive Compounds

    SciTech Connect

    Ewing, Robert G.; Clowers, Brian H.; Atkinson, David A.

    2013-10-03

    The real-time detection of vapors from low volatility explosives including PETN, tetryl, RDX and nitroglycerine along with various compositions containing these substances is demonstrated. This was accomplished with an atmospheric flow tube (AFT) using a non-radioactive ionization source and coupled to a mass spectrometer. Direct vapor detection was demonstrated in less than 5 seconds at ambient temperature without sample pre-concentration. The several seconds of residence time of analytes in the AFT provides a significant opportunity for reactant ions to interact with analyte vapors to achieve ionization. This extended reaction time, combined with the selective ionization using the nitrate reactant ions (NO3- and NO3-•HNO3), enables highly sensitive explosives detection. Observed signals from diluted explosive vapors indicate detection limits below 10 ppqv using selected ion monitoring (SIM) of the explosive-nitrate adduct at m/z 349, 378, 284 and 289 for tetryl, PETN, RDX and NG respectively. Also provided is a demonstration of the vapor detection from 10 different energetic formulations, including double base propellants, plastic explosives and commercial blasting explosives using SIM for the NG, PETN and RDX product ions.

  11. Direct Real-Time Detection of RDX Vapors Under Ambient Conditions

    SciTech Connect

    Ewing, Robert G.; Atkinson, David A.; Clowers, Brian H.

    2013-01-15

    The results in this manuscript represent a demonstration of RDX vapor detection in real time at ambient temperature without sample pre-concentration. The detection of vapors from the low volatility explosive compound RDX was achieved through selective atmospheric pressure chemical ionization using nitrate reactant ions (NO3-), and NO3-•HNO3 adducts generated in an electrical discharge source. The RDX vapors were ionized in a reaction region, which provided a variable (up to several seconds) reaction time. The reaction times were controlled by either flow in an atmospheric flow tube (AFT) or by electric field in an atmospheric drift tube (ADT). Both AFT and ADT were interfaced to a quadrupole mass spectrometer for ion detection and identification. Recorded signals were observed for RDX concentrations below 25 ppq using selected ion monitoring (SIM) of the RDX-nitrate adduct at m/z 284.

  12. Direct real-time detection of RDX vapors under ambient conditions.

    PubMed

    Ewing, Robert G; Atkinson, David A; Clowers, Brian H

    2013-01-01

    The results in this manuscript represent a demonstration of RDX vapor detection in real time at ambient temperature without sample preconcentration. The detection of vapors from the low volatility explosive compound RDX was achieved through selective atmospheric pressure chemical ionization using nitrate reactant ions (NO(3)(-)) and NO(3)(-)·HNO(3) adducts generated in an electrical discharge source. The RDX vapors were ionized in a reaction region, which provided a variable (up to several seconds) reaction time. The reaction times were controlled either by flow in an atmospheric flow tube (AFT) or by an electric field in an atmospheric drift tube (ADT). Both AFT and ADT were interfaced to a quadrupole mass spectrometer for ion detection and identification. Recorded signals were observed for RDX concentrations below 25 ppq using selected ion monitoring (SIM) of the RDX-nitrate adduct at m/z 284. PMID:23215531

  13. Extraction of rare earth oxides using supercritical carbon dioxide modified with Tri-n-butyl phosphate–nitric acid adducts

    DOE PAGES

    Baek, Donna L.; Fox, Robert V.; Case, Mary E.; Sinclair, Laura K.; Schmidt, Alex B.; McIlwain, Patrick R.; Mincher, Bruce J.; Wai, Chien M.

    2016-06-14

    A new tri-n-butylphosphate–nitric acid (TBP–HNO3) adduct was prepared by combining TBP and fuming (90%) HNO3. The adduct was characterized, and its phase-equilibrium behavior in supercritical carbon dioxide is reported. Supercritical carbon dioxide (sc-CO2) was modified with this new adduct [TBP(HNO3)5.2(H2O)1.7], and the extraction efficacies of selected rare earth oxides (Y, Ce, Eu, Tb, and Dy) at 338 K and 34.5 MPa were compared with those obtained using an adduct formed from concentrated (70%) HNO3 and TBP [TBP(HNO3)1.7(H2O)0.6]. All rare earth oxides tested with both adduct species could be extracted with the exception of cerium oxide. Furthermore, the water and acidmore » concentrations in the different adducts were found to play a significant role in rare earth oxide extraction efficiency.« less

  14. Balloon-Borne Measurements of Total Reactive Nitrogen, Nitric Acid, and Aerosol in the Cold Arctic Stratosphere

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Aimedieu, P.; Matthews, W. A.; Fahey, D. W.; Murcray, D. G.; Hofmann, D. J.; Johnston, P. V.; Iwasaka, Y.; Iwata, A.; Sheldon, W. R.

    1990-01-01

    Total reactive nitrogen (NO(Y)) between 15 and 29 km was measured for the first time on board a balloon within the Arctic cold vortex. Observations of HNO3, aerosol, and ozone were made by instruments on the same balloon gondola which was launched from Esrange, Sweden (68 deg N, 20 deg E) on January 23, 1989. The NO(y) mixing ratio was observed to increase very rapidly from 6 ppbv at 18 km altitude to a maximum of 21 ppbv at 21 km, forming a sharp layer with a thickness of about 2 km. A minimum in the NO(y) mixing ratio of 5 ppbv was found at 27 km. The measured HNO3 profile shows broad similarities to that of NO(y). This observation, together with the observed very low column amount of NO2, shows that NO(x) had been almost totally converted to HNO3, and that NO(y) was composed mainly of HNO3. The enhanced aerosol concentration between 19 and 22 km suggests that the maximum abundance of HNO3 trapped in the form of nitric acid trihydrate (NAT) was about 6 ppbv at 21 km. The sampled air parcels were highly supersaturated with respect to NAT. Although extensive denitrification throughout the stratosphere did not prevail, an indication of denitrification was found at altitudes of 27 and 22 km, and between 18 and 15 km.

  15. The formation of acid rain in the atmosphere, adjacent to the TTP with the joint-condensing of sulfur dioxide and water vapor

    NASA Astrophysics Data System (ADS)

    Gvozdyakov, D. V.; Gubin, V. E.; Matveeva, A. A.

    2014-08-01

    Presents the results of mathematical simulation of the condensation process of sulphur dioxide and water vapor on the condensation nuclei surface under the action of natural factors. Numerical investigations were carried out for the summer at a moderate speed of the wind. The influence of the parameter of condensation on the speed of the process of sulfuric acid drops formation in the air space was analyzed. Time ranges, sufficient for the formation of the acid rain sedimentation in the atmosphere, adjacent to the areas of thermal power station work were established. It is shown that the speed of air masses movement effects on the process of acid anthropogenic admixtures dispersion in the atmosphere. Approbation of the obtained results was carried out by checking the difference scheme conservative and solution of test problems.

  16. Recycling of metal-organic chemical vapor deposition waste of GaN based power device and LED industry by acidic leaching: Process optimization and kinetics study

    NASA Astrophysics Data System (ADS)

    Swain, Basudev; Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo; Lee, Chan Gi; Hong, Hyun Seon; Park, Jeung-Jin

    2015-05-01

    Recovery of metal values from GaN, a metal-organic chemical vapor deposition (MOCVD) waste of GaN based power device and LED industry is investigated by acidic leaching. Leaching kinetics of gallium rich MOCVD waste is studied and the process is optimized. The gallium rich waste MOCVD dust is characterized by XRD and ICP-AES analysis followed by aqua regia digestion. Different mineral acids are used to find out the best lixiviant for selective leaching of the gallium and indium. Concentrated HCl is relatively better lixiviant having reasonably faster kinetic and better leaching efficiency. Various leaching process parameters like effect of acidity, pulp density, temperature and concentration of catalyst on the leaching efficiency of gallium and indium are investigated. Reasonably, 4 M HCl, a pulp density of 50 g/L, 100 °C and stirring rate of 400 rpm are the effective optimum condition for quantitative leaching of gallium and indium.

  17. Derivatization coupled to headspace programmed-temperature vaporizer gas chromatography with mass spectrometry for the determination of amino acids: Application to urine samples.

    PubMed

    González Paredes, Rosa María; García Pinto, Carmelo; Pérez Pavón, José Luis; Moreno Cordero, Bernardo

    2016-09-01

    A new method based on headspace programmed-temperature vaporizer gas chromatography with mass spectrometry has been developed and validated for the determination of amino acids (alanine, sarcosine, ethylglycine, valine, leucine, and proline) in human urine samples. Derivatization with ethyl chloroformate was employed successfully to determine the amino acids. The derivatization reaction conditions as well as the variables of the headspace sampling were optimized. The existence of a matrix effect was checked and the analytical characteristics of the method were determined. The limits of detection were 0.15-2.89 mg/L, and the limits of quantification were 0.46-8.67 mg/L. The instrumental repeatability was 1.6-11.5%. The quantification of the amino acids in six urine samples from healthy subjects was performed with the method developed with the one-point standard additions protocol, with norleucine as the internal standard.

  18. Sorption of vapors of some organic liquids on soil humic acid and its relation to partitioning of organic compounds in soil organic matter

    USGS Publications Warehouse

    Chlou, G.T.; Kile, D.E.; Malcolm, R.L.

    1988-01-01

    Vapor sorption of water, ethanol, benzene, hexane, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, and 1,2-dibromoethane on (Sanhedron) soil humic acid has been determined at room temperature. Isotherms for all organic liquids are highly linear over a wide range of relative pressure (P/P??), characteristic of the partitioning (dissolution) of the organic compounds in soil humic acid. Polar liquids exhibit markedly greater sorption capacities on soil humic acid than relatively nonpolar liquids, in keeping with the polar nature of the soil humic acid as a partition medium. The limiting sorption (partition) capacities of relatively non-polar liquids are remarkably similar when expressed in terms of volumes per unit weight of soil humic acid. The soil humic acid is found to be about half as effective as soil organic matter in sorption of relatively nonpolar organic compounds. The nearly constant limiting sorption capacity for nonpolar organic liquids with soil humic acid on a volume-to-weight basis and its efficiency in sorption relative to soil organic matter provide a basis for predicting the approximate sorption (partition) coefficients of similar compounds in uptake by soil in aqueous systems.

  19. Vapor phase oxidation of benzoic acid to phenol over a novel catalyst system consisting of NiO and NiFe{sub 2}O{sub 4}

    SciTech Connect

    Miki, Jun; Asanuma, Minoru; Tachibana, Yakudo

    1995-02-01

    NiO and Fe{sub 2}O{sub 3} were found to show the catalytic activities for the vapor phase oxidation of benzoic acid to form phenol. Furthermore, the enhancement of the activity and phenol selectivity were achieved by combined Ni and Fe components prepared by precipitation. The calcination temperature and the atomic ratio of Ni to Fe were found to be important for the enhancement of activity. The homogeneous distribution profile of NiO and NiFe{sub 2}O{sub 4} on the surface and in the bulk of the catalyst is essential for the optimization of phenol formation. 32 refs., 7 figs., 4 tabs.

  20. Polymorph-dependent titanium dioxide nanoparticle dissolution in acidic and alkali digestions

    EPA Science Inventory

    Multiple polymorphs (anatase, brookite and rutile) of titanium dioxide nanoparticles (TiO2-NPs) with variable structures were quantified in environmental matrices via microwave-based hydrofluoric (HF) and nitric (HNO3) mixed acid digestion and muffle furnace (MF)-based potassium ...

  1. Nitric acid depressions in and near midlatitude cirrus clouds during TRACE-P

    NASA Astrophysics Data System (ADS)

    Zondlo, M. A.; Cantrell, C. A.; Clarke, A.; Kosciuch, E.; Mauldin, R. L.; Eisele, F. L.

    2003-12-01

    Cirrus cloud ice particles have been implicated in scavenging a wide variety soluble and semisoluble species. Species removed by an ice surface can undergo a number of significant processes including heterogeneous reactions with other adsorbed species, vertical redistribution in the troposphere from sedimenting particles, or modifying the microphysical properties of the ice particle. Nitric acid (HNO3) has been shown in the laboratory to readily adsorb onto ice surfaces, and modeling studies suggest significant perturbations to its distribution can result. Unfortunately, field observations of HNO3 within and near cirrus clouds have shown mixed and sometimes contradictory results. The NASA P-3B aircraft sampled numerous upper tropospheric, mid-latitude ice clouds during Flight 24 of the NASA TRACE-P field experiment. In contrast to tropical cirrus clouds, the cirrus ice clouds sampled by the P-3B were at warmer temperatures of -17 to -32 degrees Celsius and at pressures of 365-436 mb. The clouds' origins ranged from jet stream induced cirrostratus clouds to convectively-induced cirrus anvils. Nitric acid levels decreased 60-70 pptv (35-60%) within the clouds compared to areas just outside of it. Slight asymmetries in the HNO3 profiles around the cloud were noted, with the lee or downwind sides of clouds containing more gradual returns from inside cloud levels to "background" levels, potentially due to greater mixing as the cloud evaporated. If HNO3 removed inside the cloud were distributed evenly onto ice surfaces, approximately one tenth of a monolayer of HNO3 was adsorbed onto ice (based on estimates of ice surface area density of 5000 microns squared per cubic centimeter). The incorporation of HNO3 into existing liquid quaternary NH3/H2SO4/HNO3/H2O aerosols within the cloud could also be important due to the sampling location over central North America where elevated NH3 emissions exist. The midlatitude HNO3/cirrus cases observed on the P-3B will be contrasted to

  2. Oxidative degradation of bis (2,4,4-trimethylpentyl) dithiophosphinic acid in nitric acid studied by electrospray ionization mass spectrometry

    SciTech Connect

    G. S. Groenewold; D. R. Peterman

    2012-10-01

    Samples of bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex-301) were analyzed using direct infusion electrospray ionization mass spectrometry. Positive ion spectra of standard and stereo-pure acids displayed ions typical of the unmodified compound, cationized monomeric and dimeric cluster ion species. In addition, a significant ions 2 u less than the dimeric clusters were seen, that correspond to an oxidatively coupled species designated Cyx2 that is observed as H- or Na-cationized species in the electrospray analyses. Based on uncorrected ion intensities, Cyx2 is estimated to account for about 20% of the total in the standard materials. When samples that were contacted with 3 M HNO3 were analyzed, the positive ion spectrum consisted nearly entirely of ions derived from the oxidatively coupled product, indicating that the acid promotes coupling. The negative ion spectra of the standard acids consisted nearly entirely of the conjugate base that is formed by deprotonation of the acids, and cluster ions containing multiple acid molecules. The negative spectra of the HNO3-contacted samples also contained the conjugate base of the unmodified acid, but also two other species that correspond to the dioxo- and perthio- derivatives. It is concluded that HNO3 contact causes significant oxidation, forming at least three major products, Cyx2, the perthio-acid, and the dioxo-acid.

  3. Laboratory evaluation of the effect of nitric acid uptake on frost point hygrometer performance

    NASA Astrophysics Data System (ADS)

    Thornberry, T.; Gierczak, T.; Gao, R. S.; Vömel, H.; Watts, L. A.; Burkholder, J. B.; Fahey, D. W.

    2011-02-01

    Chilled mirror hygrometers (CMH) are widely used to measure water vapour in the troposphere and lower stratosphere from balloon-borne sondes. Systematic discrepancies among in situ water vapour instruments have been observed at low water vapour mixing ratios (<5 ppm) in the upper troposphere and lower stratosphere (UT/LS). Understanding the source of the measurement discrepancies is important for a more accurate and reliable determination of water vapour abundance in this region. We have conducted a laboratory study to investigate the potential interference of gas-phase nitric acid (HNO3) with the measurement of frost point temperature, and consequently the water vapour mixing ratio, determined by CMH under conditions representative of operation in the UT/LS. No detectable interference in the measured frost point temperature was found for HNO3 mixing ratios of up to 4 ppb for exposure times up to 150 min. HNO3 was observed to co-condense on the mirror frost, with the adsorbed mass increasing linearly with time at constant exposure levels. Over the duration of a typical balloon sonde ascent (90-120 min), the maximum accumulated HNO3 amounts were comparable to monolayer coverage of the geometric mirror surface area, which corresponds to only a small fraction of the actual frost layer surface area. This small amount of co-condensed HNO3 is consistent with the observed lack of HNO3 interference in the frost point measurement because the CMH utilizes significant reductions (>10%) in surface reflectivity by the condensate to determine H2O.

  4. Laboratory evaluation of the effect of nitric acid uptake on frost point hygrometer performance

    NASA Astrophysics Data System (ADS)

    Thornberry, T.; Gierczak, T.; Gao, R. S.; Vömel, H.; Watts, L. A.; Burkholder, J. B.; Fahey, D. W.

    2010-08-01

    Chilled mirror hygrometers (CMH) are widely used to measure water vapour in the troposphere and lower stratosphere from balloon-borne sondes. Systematic discrepancies among in situ water vapour instruments have been observed at low water vapour mixing ratios (<5 ppm) in the upper troposphere and lower stratosphere (UT/LS). Understanding the source of the measurement discrepancies is important for a more accurate and reliable determination of water vapour abundance in this region. We have conducted a laboratory study to investigate the potential interference of gas-phase nitric acid (HNO3) with the measurement of frost point temperature, and consequently the water vapour mixing ratio, determined by CMH under conditions representative of operation in the UT/LS. No detectable interference in the measured frost point temperature was found for HNO3 mixing ratios of up to 4 ppb for exposure times up to 150 min. HNO3 was observed to co-condense on the mirror frost, with the adsorbed mass increasing linearly with time at constant exposure levels. Over the duration of a typical balloon sonde ascent (90-120 min), the maximum accumulated HNO3 amounts were comparable to monolayer coverage of the geometric mirror surface area, which corresponds to only a small fraction of the actual frost layer surface area. This small amount of co-condensed HNO3 is consistent with the observed lack of HNO3 interference in the frost point measurement because the CMH utilizes significant reductions (>10%) in surface reflectivity by the condensate to determine H2O.

  5. Advanced zirconia-coated carbonyl-iron particles for acidic magnetorheological finishing of chemical-vapor-deposited ZnS and other IR materials

    NASA Astrophysics Data System (ADS)

    Salzman, S.; Giannechini, L. J.; Romanofsky, H. J.; Golini, N.; Taylor, B.; Jacobs, S. D.; Lambropoulos, J. C.

    2015-10-01

    We present a modified version of zirconia-coated carbonyl-iron (CI) particles that were invented at the University of Rochester in 2008. The amount of zirconia on the coating is increased to further protect the iron particles from corrosion when introduced to an acidic environment. Five low-pH, magnetorheological (MR) fluids were made with five acids: acetic, hydrochloric, nitric, phosphoric, and hydrofluoric. All fluids were based on the modified zirconia-coated CI particles. Off-line viscosity and pH stability were measured for all acidic MR fluids to determine the ideal fluid composition for acidic MR finishing of chemical-vapor-deposited (CVD) zinc sulfide (ZnS) and other infrared (IR) optical materials, such as hot-isostatic-pressed (HIP) ZnS, CVD zinc selenide (ZnSe), and magnesium fluoride (MgF2). Results show significant reduction in surface artifacts (millimeter-size, pebble-like structures on the finished surface) for several standard-grade CVD ZnS substrates and good surface roughness for the non-CVD MgF2 substrate when MR finished with our advanced acidic MR fluid.

  6. Tuning the acid/metal balance of carbon nanofiber-supported nickel catalysts for hydrolytic hydrogenation of cellulose.

    PubMed

    Van de Vyver, Stijn; Geboers, Jan; Schutyser, Wouter; Dusselier, Michiel; Eloy, Pierre; Dornez, Emmie; Seo, Jin Won; Courtin, Christophe M; Gaigneaux, Eric M; Jacobs, Pierre A; Sels, Bert F

    2012-08-01

    Carbon nanofibers (CNFs) are a class of graphitic support materials with considerable potential for catalytic conversion of biomass. Earlier, we demonstrated the hydrolytic hydrogenation of cellulose over reshaped nickel particles attached at the tip of CNFs. The aim of this follow-up study was to find a relationship between the acid/metal balance of the Ni/CNFs and their performance in the catalytic conversion of cellulose. After oxidation and incipient wetness impregnation with Ni, the Ni/CNFs were characterized by various analytical methods. To prepare a selective Ni/CNF catalyst, the influences of the nature of oxidation agent, Ni activation, and Ni loading were investigated. Under the applied reaction conditions, the best result, that is, 76 % yield in hexitols with 69 % sorbitol selectivity at 93 % conversion of cellulose, was obtained on a 7.5 wt % Ni/CNF catalyst prepared by chemical vapor deposition of CH(4) on a Ni/γ-Al(2)O(3) catalyst, followed by oxidation in HNO(3) (twice for 1 h at 383 K), incipient wetness impregnation, and reduction at 773 K under H(2). This preparation method leads to a properly balanced Ni/CNF catalyst in terms of Ni dispersion and hydrogenation capacity on the one hand, and the number of acidic surface-oxygen groups responsible for the acid-catalyzed hydrolysis on the other.

  7. Tuning the acid/metal balance of carbon nanofiber-supported nickel catalysts for hydrolytic hydrogenation of cellulose.

    PubMed

    Van de Vyver, Stijn; Geboers, Jan; Schutyser, Wouter; Dusselier, Michiel; Eloy, Pierre; Dornez, Emmie; Seo, Jin Won; Courtin, Christophe M; Gaigneaux, Eric M; Jacobs, Pierre A; Sels, Bert F

    2012-08-01

    Carbon nanofibers (CNFs) are a class of graphitic support materials with considerable potential for catalytic conversion of biomass. Earlier, we demonstrated the hydrolytic hydrogenation of cellulose over reshaped nickel particles attached at the tip of CNFs. The aim of this follow-up study was to find a relationship between the acid/metal balance of the Ni/CNFs and their performance in the catalytic conversion of cellulose. After oxidation and incipient wetness impregnation with Ni, the Ni/CNFs were characterized by various analytical methods. To prepare a selective Ni/CNF catalyst, the influences of the nature of oxidation agent, Ni activation, and Ni loading were investigated. Under the applied reaction conditions, the best result, that is, 76 % yield in hexitols with 69 % sorbitol selectivity at 93 % conversion of cellulose, was obtained on a 7.5 wt % Ni/CNF catalyst prepared by chemical vapor deposition of CH(4) on a Ni/γ-Al(2)O(3) catalyst, followed by oxidation in HNO(3) (twice for 1 h at 383 K), incipient wetness impregnation, and reduction at 773 K under H(2). This preparation method leads to a properly balanced Ni/CNF catalyst in terms of Ni dispersion and hydrogenation capacity on the one hand, and the number of acidic surface-oxygen groups responsible for the acid-catalyzed hydrolysis on the other. PMID:22730195

  8. Stratospheric aerosol acidity, density, and refractive index deduced from SAGE 2 and NMC temperature data

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Poole, L. R.; Wang, P.-H.; Chiou, E. W.

    1994-01-01

    Water vapor concentrations obtained by the Stratospheric Aerosol and Gas Experiment 2 (SAGE 2) and collocated temperatures provided by the National Meteorological Center (NMC) from 1986 to 1990 are used to deduce seasonally and zonally averaged acidity, density, and refractive index of stratospheric aerosols. It is found that the weight percentage of sulfuric acid in the aerosols increases from about 60 just above the tropopause to about 86 at 35 km. The density increases from about 1.55 to 1.85 g/cu cm between the same altitude limits. Some seasonal variations of composition and density are evident at high latitudes. The refractive indices at 1.02, 0.694, and 0.532 micrometers increase, respectively, from about 1.425, 1.430, and 1.435 just above the tropopause to about 1.445, 1.455, and 1.458 at altitudes above 27 km, depending on the season and latitude. The aerosol properties presented can be used in models to study the effectiveness of heterogeneous chemistry, the mass loading of stratospheric aerosols, and the extinction and backscatter of aerosols at different wavelengths. Computed aerosol surface areas, rate coefficients for the heterogeneous reaction ClONO2 + H2O yields HOCl + HNO3 and aerosol mass concentrations before and after the Pinatubo eruption in June 1991 are shown as sample applications.

  9. Field test of four methods for gas-phase ambient nitric acid

    NASA Astrophysics Data System (ADS)

    Arnold, J. R.; Hartsell, Benjamin E.; Luke, Winston T.; Rahmat Ullah, S. M.; Dasgupta, Purnendu K.; Greg Huey, L.; Tate, Paul

    Three semi-continuous methods for detecting nitric acid (HNO 3) were tested against the annular denuder + filter pack (ADS) integrated collection technique at the Tampa Bay Regional Atmospheric Chemistry Experiment (BRACE) Sydney research station ˜20km downwind of the Tampa, Florida, urban core. The semi-continuous instruments included: two slightly differing implementations of the NOY-NO (total oxides of nitrogen minus that total denuded of HNO 3) denuder difference technique, one from the NOAA Air Resources Lab (ARL), and one from Atmospheric Research and Analysis, Inc. (ARA); the parallel plate wet diffusion scrubber + online ion chromatography technique from Texas Tech University (TTU); and the chemical ionization mass spectrometer from the Georgia Institute of Technology (GIT). Twelve hour ADS samples were collected by the University of South Florida (USF). Results for 10 min samples computed from the various higher sampling frequencies of each semi-continuous instrument showed good agreement (R2>0.7) for afternoon periods of the highest production and accumulation of HNO 3. Further, agreement was within ±30% for these instruments even at HNO 3 concentrations <0.30ppb. The USF ADS results were biased low, however, by 44%, on average, compared to the corporate 12 h aggregated means from the semi-continuous methods, and by >60% for the nighttime samples; ADS results were below the corporate mean maximum HNO 3 concentration by >30% as well. The four instruments using semi-continuous methods, by contrast, were all within 10% of each other's 12 h mean mixing ratios. While only ARA employed a formal minimum detection limit at 0.050 ppb, error analysis with the other techniques established that at the same level of precision, TTU's effective limit was approximately the same as ARA's and that ARL's limit was 0.030 ppb; analysis for GIT showed no apparent effective limit at the levels of HNO 3 encountered in this field study. The importance of sample inlet height for

  10. The Effect of Incorporation of HNO(sub 3) Into Liquid Sulfuric Acid on Heterogeneous Reaction Probabilities

    NASA Technical Reports Server (NTRS)

    Zhang, R.; Leu, M-T.; Keyser, L.

    1994-01-01

    Using a fast-flow reactor coupled to a quadrupole mass spectrometer, the heterogeneous reactions of C1ONO2 + HCl and HOCl + HCl as well as hydrolysis of N2O5 and C1ONO2 were investigated on liquid sulfuric acid, with particular emphasis on the effect of incorporation of HNO3 on the reaction probabilities.

  11. Vapor Explosions

    NASA Astrophysics Data System (ADS)

    Berthoud, Georges

    A vapor explosion results from the rapid and intense heat transfer that may follow contact between a hot liquid and a cold, more volatile one. Because it can happen during severe-accident sequences of a nuclear power plan, that is, when a large part of the core is molten, vapor explosions have been widely studied. The different sequences of a vapor explosion are presented, including premixing, triggering, propagation, and expansion. Typical experimental results are also analyzed to understand the involved physics. Then the different physics involved in the sequences are addressed, as well as the present experimental program.

  12. Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts

    SciTech Connect

    Wang, Bingbing; Laskin, Alexander

    2014-03-25

    Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate Ca(NO3)2 when nitrogen oxide and nitric acid (HNO3) species react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here, we present a systematic microanalysis study on chemical composition of laboratory generated particles composed of water soluble organic acids and nitrates (i.e. NaNO3 and Ca(NO3)2) investigated using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and Fourier transform infrared micro-spectroscopy (micro-FTIR). The results show that water-soluble organic acids can react with nitrates releasing gaseous HNO3 during dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase due to its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that in turn may affect their physical and chemical properties relevant to atmospheric environment and climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling, which may further affect concentrations of gas- and aerosol-phase species in the atmosphere and the heterogeneous reaction chemistry between them.

  13. Application of Lactobacillus immobilized by Activated Carbon Fiber in Fermentation of Lactic Acid in Starch Wastewater

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Wang, Peng; Chi, Guoda; Huang, Chenyong

    2010-11-01

    Activated carbon fibers (ACF) as the carrier of Lactobacillus was introduced into fermenting system, and a method of modifying the surface of ACF by HNO3-Fe (III) was established. Factors that affect ACF carrier's effect on immobilization of Lactobacillus were studied. HCl, H2SO4, HNO3 and FeCl3 solutions were respectively used to modify the surface properties of ACF. The amount of Fe (III) carried on ACF surface was 0.1563 mol/kg after ACF surface was modified by HNO3 for 5 h and then by 0.1 mol/L FeCl3 for 4 h, when the thickness of Lactobacillus on a single silk of carrier reached 40 μm. When ACF modified by HNO3-Fe (III) was applied in the fermentation of lactic acid in starch industry wastewater, the fermentation period reduced by 8 h and the output of L-lactic acid was 65.5 g/L, which was 3.3% more than that fermented without the carrier.

  14. Electrolyte vapor condenser

    DOEpatents

    Sederquist, Richard A.; Szydlowski, Donald F.; Sawyer, Richard D.

    1983-01-01

    A system is disclosed for removing electrolyte from a fuel cell gas stream. The gas stream containing electrolyte vapor is supercooled utilizing conventional heat exchangers and the thus supercooled gas stream is passed over high surface area passive condensers. The condensed electrolyte is then drained from the condenser and the remainder of the gas stream passed on. The system is particularly useful for electrolytes such as phosphoric acid and molten carbonate, but can be used for other electrolyte cells and simple vapor separation as well.

  15. Electrolyte vapor condenser

    DOEpatents

    Sederquist, R.A.; Szydlowski, D.F.; Sawyer, R.D.

    1983-02-08

    A system is disclosed for removing electrolyte from a fuel cell gas stream. The gas stream containing electrolyte vapor is supercooled utilizing conventional heat exchangers and the thus supercooled gas stream is passed over high surface area passive condensers. The condensed electrolyte is then drained from the condenser and the remainder of the gas stream passed on. The system is particularly useful for electrolytes such as phosphoric acid and molten carbonate, but can be used for other electrolyte cells and simple vapor separation as well. 3 figs.

  16. Chemical Degradation Studies on a Series of Dithiophosphinic Acids

    SciTech Connect

    Freiderich, Melissa E; Delmau, Laetitia Helene; Peterman, D. R.; Marc, Philippe L; Klaehn, John D.

    2014-01-01

    In this study a significant increase in the stability of a series of dithiophosphinic acids (DPAHs) under oxidizing acidic conditions was achieved. The degradation behavior of a series of DPAHs, designed for lanthanide/actinide separation, was examined. The stability of the DPAHs, when contacted with varying nitric acid concentrations, was tested and monitored using 31P {1H} NMR. Changes in the functional groups of the DPAHs resulted in substantial increases in the stability. However, all the DPAHs eventually showed signs of degradation when placed in contact with 2 M HNO3. The addition of a radical scavenger, hydrazine, inhibited the degradation of the DPAHs. With small amounts of hydrazine, five of the DPAHs remained stable for over a month in direct contact with 2 M HNO3.

  17. Chemical Degradation Studies on a Series of Dithiophosphinic Acids

    SciTech Connect

    Melissa E. Freiderich; Dean R. Peterman; John R. Klaehn; Philippe Marc; Laetitia H. Delmau

    2014-04-01

    A significant increase in the stability of a series of dithiophosphinic acids (DPAHs) under oxidizing acidic conditions was achieved. The degradation behavior of a series of DPAHs, designed for lanthanide/actinide separation, was examined. The stability of the DPAHs, when contacted with varying nitric acid concentrations, was tested and monitored using 31P {1H} NMR. Changes in the functional groups of the DPAHs resulted in substantial increases in the stability. However, when placed in contact with 2 M HNO3 all the DPAHs eventually showed signs of degradation. The addition of a radical scavenger, hydrazine, inhibited the degradation of the DPAHs. In the presence of a small concentration of hydrazine, five of the DPAHs remained stable for over a month in direct contact with 2 M HNO3.

  18. Formation of C═C bond via knoevenagel reaction between aromatic aldehyde and barbituric acid at liquid/HOPG and vapor/HOPG interfaces.

    PubMed

    Geng, Yanfang; Dai, Hongliang; Chang, Shaoqing; Hu, Fangyun; Zeng, Qingdao; Wang, Chen

    2015-03-01

    Controlling chemical reactions on surface is of great importance to constructing self-assembled covalent nanostructures. Herein, Knoevenagel reaction between aromatic aldehyde compound 2,5-di(5-aldehyde-2-thienyl)-1,4-dioctyloxybenzene (PT2) and barbituric acid (BA) has been successfully performed for the first time at liquid/HOPG interface and vapor/HOPG interface. The resulting surface nanostructures and the formation of C═C bond are recorded through scanning tunneling microscopy (STM), and confirmed by attenuated total reflectance Fourier-transform infrared (ATR/FT-IR) spectrometer and UV-vis absorption. The obtained results reveal that Knoevenagel condensation reaction can efficiently occur at both interfaces. This surface reaction would be an important step toward further reaction to produce innovative conjugated nanomaterial on the surface.

  19. Incorporation of stratospheric acids into water ice

    NASA Technical Reports Server (NTRS)

    Elliott, Scott; Turco, Richard P.; Toon, Owen B.; Hamill, Patrick

    1990-01-01

    Hydrochloric and hydrofluoric acids are absorbed within the water ice lattice at mole fractions maximizing below 0.00001 and 0.0001 in a variety of solid impurity studies. The absorption mechanism may be substitutional or interstitial, leading in either case to a weak permeation of stratospheric ices by the acids at equilibrium. Impurities could also inhabit grain boundaries, and the acid content of atmospheric ice crystals will then depend on details of their surface and internal microstructures. Limited evidence indicates similar properties for the absorption of HNO3. Water ice lattices saturated with acid cannot be a significant local reservoir for HCl in the polar stratosphere.

  20. Thermal Decomposition of Gaseous Ammonium Nitrate at Low Pressure: Kinetic Modeling of Product Formation and Heterogeneous Decomposition of Nitric Acid

    NASA Astrophysics Data System (ADS)

    Park, J.; Lin, M. C.

    2009-10-01

    The thermal decomposition of ammonium nitrate, NH4NO3 (AN), in the gas phase has been studied at 423-56 K by pyrolysis/mass spectrometry under low-pressure conditions using a Saalfeld reactor coated with boric acid. The sublimation of NH4NO3 at 423 K was proposed to produce equal amounts of NH3 and HNO3, followed by the decomposition reaction of HNO3, HNO3 + M → OH + NO2 + M (where M = third-body and reactor surface). The absolute yields of N2, N2O, H2O, and NH3, which can be unambiguously measured and quantitatively calibrated under a constant pressure at 5-6.2 torr He are kinetically modeled using the detailed [H,N,O]-mechanism established earlier for the simulation of NH3-NO2 (Park, J.; Lin, M. C. Technologies and Combustion for a Clean Environment. Proc. 4th Int. Conf. 1997, 34-1, 1-5) and ADN decomposition reactions (Park, J.; Chakraborty, D.; Lin, M. C. Proc. Combust. Inst. 1998, 27, 2351-2357). Since the homogeneous decomposition reaction of HNO3 itself was found to be too slow to account for the consumption of reactants and the formation of products, we also introduced the heterogeneous decomposition of HNO3 in our kinetic modeling. The heterogeneous decomposition rate of HNO3, HNO3 + (B2O3/SiO2) → OH + NO2 + (B2O3/SiO2), was determined by varying its rate to match the modeled result to the measured concentrations of NH3 and H2O; the rate could be represented by k2b = 7.91 × 107 exp(-12 600/T) s-1, which appears to be consistent with those reported by Johnston and co-workers (Johnston, H. S.; Foering, L.; Tao, Y.-S.; Messerly, G. H. J. Am. Chem. Soc. 1951, 73, 2319-2321) for HNO3 decomposition on glass reactors at higher temperatures. Notably, the concentration profiles of all species measured could be satisfactorily predicted by the existing [H,N,O]-mechanism with the heterogeneous initiation process.

  1. Graphene decorated microelectrodes for simultaneous detection of ascorbic, dopamine, and folic acids by means of chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Namdar, N.; Hassanpour Amiri, M.; Dehghan Nayeri, F.; Gholizadeh, A.; Mohajerzadeh, S.

    2015-09-01

    In this paper, high quality and large area graphene layers were synthesized using thermal chemical vapour deposition on copper foil substrates. We use graphene incorporated electrodes to measure simultaneously ascorbic acid, dopamine and folic acid. Cyclic voltammetry and differential pulse voltammetry methods were used to evaluate electrochemical behaviour of the grown graphene layers. The graphene-modified electrode shows large electrochemical potential difference compared to bare gold electrodes with higher current responses. Also our fabricated electrodes configuration can be used easily for microfluidic analysis.

  2. Vapor fragrancer

    NASA Astrophysics Data System (ADS)

    Sang, Q. Tran; Bryant, Timothy D.

    1987-05-01

    This invention relates to a vapor fragrancer for continuously, uniformly, and economically odorizing or deodorizing an environment. Homes, offices, automobiles, and space stations require either odorizing or deodorizing of the atmosphere to create pleasant conditions for work or leisure. A vapor fragrancer is provided to accomplish these goals. A supplier continuously supplies a predetermined amount of desired liquid fragrance from a container to a retaining material, which is positioned in the circulation path of the atmosphere. The supplier is either a low powered pump or a gravity dispenser. The atmosphere flowing in a circulation path passes over the retaining material containing the liquid fragrance and lifts a fragrant vapor from the retaining material. The atmosphere is thereby continuously and uniformly fragranced.

  3. Dispersibility of vapor phase oxygen and nitrogen functionalized multi-walled carbon nanotubes in various organic solvents

    NASA Astrophysics Data System (ADS)

    Khazaee, Maryam; Xia, Wei; Lackner, Gerhard; Mendes, Rafael G.; Rümmeli, Mark; Muhler, Martin; Lupascu, Doru C.

    2016-05-01

    The synthesis and characterization of gas phase oxygen- and nitrogen-functionalized multi-walled carbon nanotubes (OMWCNTs and NMWCNTs) and the dispersibility of these tubes in organic solvents were investigated. Recently, carbon nanotubes have shown supreme capacity to effectively enhance the efficiency of organic solar cells (OSCs). A critical challenge is to individualize tubes from their bundles in order to provide homogenous nano-domains in the active layer of OSCs. OMWCNTs and NMWCNTs were synthesized via HNO3 vapor and NH3 treatments, respectively. Surface functional groups and the structure of the tubes were analyzed by temperature-programmed desorption, Fourier transform infrared spectroscopy, transmission electron microscopy, and Raman spectroscopy which confirmed the formation of functional groups on the tube surface and the enhancement of surface defects. Elemental analysis demonstrated that the oxygen and nitrogen content increased with increasing treatment time of the multi-walled carbon nanotube (MWCNT) in HNO3 vapor. According to ultra-violet visible spectroscopy, modification of the MWCNT increased the extinction coefficients of the tubes owing to enhanced compatibility of the functionalized tubes with organic matrices.

  4. Dispersibility of vapor phase oxygen and nitrogen functionalized multi-walled carbon nanotubes in various organic solvents

    PubMed Central

    Khazaee, Maryam; Xia, Wei; Lackner, Gerhard; Mendes, Rafael G.; Rümmeli, Mark; Muhler, Martin; Lupascu, Doru C.

    2016-01-01

    The synthesis and characterization of gas phase oxygen- and nitrogen-functionalized multi-walled carbon nanotubes (OMWCNTs and NMWCNTs) and the dispersibility of these tubes in organic solvents were investigated. Recently, carbon nanotubes have shown supreme capacity to effectively enhance the efficiency of organic solar cells (OSCs). A critical challenge is to individualize tubes from their bundles in order to provide homogenous nano-domains in the active layer of OSCs. OMWCNTs and NMWCNTs were synthesized via HNO3 vapor and NH3 treatments, respectively. Surface functional groups and the structure of the tubes were analyzed by temperature-programmed desorption, Fourier transform infrared spectroscopy, transmission electron microscopy, and Raman spectroscopy which confirmed the formation of functional groups on the tube surface and the enhancement of surface defects. Elemental analysis demonstrated that the oxygen and nitrogen content increased with increasing treatment time of the multi-walled carbon nanotube (MWCNT) in HNO3 vapor. According to ultra-violet visible spectroscopy, modification of the MWCNT increased the extinction coefficients of the tubes owing to enhanced compatibility of the functionalized tubes with organic matrices. PMID:27188622

  5. Quantifying wet scavenging processes in aircraft observations of nitric acid and cloud condensation nuclei

    NASA Astrophysics Data System (ADS)

    Garrett, T. J.; Avey, L.; Palmer, P. I.; Stohl, A.; Neuman, J. A.; Brock, C. A.; Ryerson, T. B.; Holloway, J. S.

    2006-12-01

    Wet scavenging is an important sink term for many atmospheric constituents. However, production of precipitation in clouds is poorly understood, and pollutant removal through wet scavenging is difficult to separate from removal through dry scavenging, atmospheric mixing, or chemical transformations. Here we use airborne data from the International Consortium for Atmospheric Research on Transport and Transformation project to show that measured ratios of soluble and insoluble trace gases provide a useful indicator for quantifying wet scavenging. Specifically, nitric acid (HNO3), produced as a by-product of combustion, is highly soluble and removed efficiently from clouds by rain. Regional carbon monoxide (CO), which is also an indicator of anthropogenic activity, is insoluble and has a lifetime against oxidation of about a month. We find that relative concentrations of HNO3 to regional CO observed in clear air are negatively correlated with precipitation production rates in nearby cloudy air (r2 = 0.85). Also, we show that relative concentrations of HNO3 and CO can be used to quantify cloud condensation nucleus (CCN) scavenging by precipitating clouds. This is because CCN and HNO3 molecules are both fully soluble in cloud water and hence can be treated as analogous species insofar as wet scavenging is concerned. While approximate, the practical advantage of this approach to scavenging studies is that it requires only measurement in clear air and no a priori knowledge of the cloud or aerosol properties involved.

  6. Modification of the surface chemistry of single- and multi-walled carbon nanotubes by HNO3 and H2SO4 hydrothermal oxidation for application in direct contact membrane distillation.

    PubMed

    Morales-Torres, Sergio; Silva, Tânia L S; Pastrana-Martínez, Luisa M; Brandão, Ana T S C; Figueiredo, José L; Silva, Adrián M T

    2014-06-28

    A specific methodology based on nitric acid hydrothermal oxidation was used to control the surface chemistry of multi-walled (MWCNTs) and single-walled (SWCNTs) carbon nanotubes (CNTs) with different lengths, and this methodology was adapted to the use of sulphuric acid containing ammonium persulfate as an oxidizing agent. The amount of oxygen-containing surface groups depends on the number and length of the graphene layers of the CNTs, thicker and shorter CNTs having more reactive sites for surface functionalization. In particular, the oxidation of MWCNTs was more pronounced than that of short SWCNTs and less surface groups were introduced into long SWCNTs, regardless of the acid used at any fixed concentration. It was also possible to tailor the surface chemistry of both SWCNTs and MWCNTs by using the adopted methodologies, and the amount of both oxygen- and sulphur-containing functional groups was correlated with the concentration of each oxidizing agent used. Mathematical functions that allow precise control of the amount and type of the surface groups introduced into carbon nanotubes were obtained. Buckypapers were also prepared over a polytetrafluoroethylene commercial membrane. These membranes were tested in direct contact membrane distillation and, under salinity conditions, the membrane prepared using oxidized MWCNTs (instead of SWCNTs) was the most efficient, the permeate flux of the commercial membrane significantly increasing in the presence of these CNTs, while completely rejecting chloride ions. In addition, the permeate flux was precisely correlated with the amount of oxygenated functional surface groups (as well as with the pH of point of zero charge) of the oxidized MWCNTs. PMID:24821484

  7. Nitric acid dry deposition to conifer forests: Niwot Ridge spruce-fir-pine study

    USGS Publications Warehouse

    Sievering, H.; Kelly, T.; McConville, G.; Seibold, C.; Turnipseed, A.

    2001-01-01

    The dry deposition velocity of nitric acid, Vd(HNO3), over a 12-m (mean height) spruce-fir forest at Niwot Ridge, Colorado was estimated during 13 daytime periods using the flux-gradient approach. Turbulence intensity at this site is high (mean u* of 0.65ms-1 with u of 2.9ms-1) and contributed to the large observed Vd(HNO3). The overriding contributor is identified to be the small aerodynamic needle width of the conifer trees. Two cases had inflated Vd(HNO3) due to height-differentiated nitric acid loss to soil-derived particle surfaces. Not considering these cases, the mean Vd(HNO3) was 7.6cms-1. The mean laminar boundary layer resistance (Rb) was found to be 7.8sm-1 (of similar magnitude to that of the aerodynamic resistance, 8.5sm-1). The data-determined Rb is bracketed by two theoretical estimates of the mean Rb, 5.9 and 8.6sm-1, that include consideration of the small canopy length scale (aerodynamic needle width), 1mm or less, at this conifer forest. However, the poor correlation of data-determined Rb values with both sets of theoretical estimates indicates that measurement error needs to be reduced and/or improved formulations of theoretical Rb values are in order. The large observed Vd(HNO3) at this conifer forest site is attributed to high turbulence intensity, and, especially, to small aerodynamic needle width. Copyright ?? 2001 Elsevier Science Ltd.

  8. Microbial Community Structure and Arsenic Biogeochemistry in an Acid Vapor-Formed Spring in Tengchong Geothermal Area, China.

    PubMed

    Jiang, Zhou; Li, Ping; Jiang, Dawei; Dai, Xinyue; Zhang, Rui; Wang, Yanhong; Wang, Yanxin

    2016-01-01

    Arsenic biogeochemistry has been studied extensively in acid sulfate-chloride hot springs, but not in acid sulfate hot springs with low chloride. In this study, Zhenzhuquan in Tengchong geothermal area, a representative acid sulfate hot spring with low chloride, was chosen to study arsenic geochemistry and microbial community structure using Illumina MiSeq sequencing. Over 0.3 million 16S rRNA sequence reads were obtained from 6-paired parallel water and sediment samples along its outflow channel. Arsenic oxidation occurred in the Zhenxhuquan pool, with distinctly high ratios of arsenate to total dissolved arsenic (0.73-0.86). Coupled with iron and sulfur oxidation along the outflow channel, arsenic accumulated in downstream sediments with concentrations up to 16.44 g/kg and appeared to significantly constrain their microbial community diversity. These oxidations might be correlated with the appearance of some putative functional microbial populations, such as Aquificae and Pseudomonas (arsenic oxidation), Sulfolobus (sulfur and iron oxidation), Metallosphaera and Acidicaldus (iron oxidation). Temperature, total organic carbon and dissolved oxygen significantly shaped the microbial community structure of upstream and downstream samples. In the upstream outflow channel region, most microbial populations were microaerophilic/anaerobic thermophiles and hyperthermophiles, such as Sulfolobus, Nocardia, Fervidicoccus, Delftia, and Ralstonia. In the downstream region, aerobic heterotrophic mesophiles and thermophiles were identified, including Ktedonobacteria, Acidicaldus, Chthonomonas and Sphingobacteria. A total of 72.41-95.91% unassigned-genus sequences were derived from the downstream high arsenic sediments 16S rRNA clone libraries. This study could enable us to achieve an integrated understanding on arsenic biogeochemistry in acid hot springs.

  9. Microbial Community Structure and Arsenic Biogeochemistry in an Acid Vapor-Formed Spring in Tengchong Geothermal Area, China

    PubMed Central

    Jiang, Zhou; Li, Ping; Jiang, Dawei; Dai, Xinyue; Zhang, Rui; Wang, Yanhong; Wang, Yanxin

    2016-01-01

    Arsenic biogeochemistry has been studied extensively in acid sulfate-chloride hot springs, but not in acid sulfate hot springs with low chloride. In this study, Zhenzhuquan in Tengchong geothermal area, a representative acid sulfate hot spring with low chloride, was chosen to study arsenic geochemistry and microbial community structure using Illumina MiSeq sequencing. Over 0.3 million 16S rRNA sequence reads were obtained from 6-paired parallel water and sediment samples along its outflow channel. Arsenic oxidation occurred in the Zhenxhuquan pool, with distinctly high ratios of arsenate to total dissolved arsenic (0.73–0.86). Coupled with iron and sulfur oxidation along the outflow channel, arsenic accumulated in downstream sediments with concentrations up to 16.44 g/kg and appeared to significantly constrain their microbial community diversity. These oxidations might be correlated with the appearance of some putative functional microbial populations, such as Aquificae and Pseudomonas (arsenic oxidation), Sulfolobus (sulfur and iron oxidation), Metallosphaera and Acidicaldus (iron oxidation). Temperature, total organic carbon and dissolved oxygen significantly shaped the microbial community structure of upstream and downstream samples. In the upstream outflow channel region, most microbial populations were microaerophilic/anaerobic thermophiles and hyperthermophiles, such as Sulfolobus, Nocardia, Fervidicoccus, Delftia, and Ralstonia. In the downstream region, aerobic heterotrophic mesophiles and thermophiles were identified, including Ktedonobacteria, Acidicaldus, Chthonomonas and Sphingobacteria. A total of 72.41–95.91% unassigned-genus sequences were derived from the downstream high arsenic sediments 16S rRNA clone libraries. This study could enable us to achieve an integrated understanding on arsenic biogeochemistry in acid hot springs. PMID:26761709

  10. The Consistency of Isotopologues of Ambient Atmospheric Nitric Acid in Passively Collected Samples

    NASA Astrophysics Data System (ADS)

    Bell, M. D.; Sickman, J. O.; Bytnerowicz, A.; Padgett, P.; Allen, E. B.

    2012-12-01

    Anthropogenic sources of nitrogen oxides have previously been shown to have distinctive isotopic signatures of oxygen and nitrogen. Nylon filters are currently used in passive sampling arrays to measure ambient atmospheric nitric acid concentrations and estimate deposition rates. This experiment measured the ability of nylon filters to consistently collect isotopologues of atmospheric nitric acid in the same ratios as they are present in the atmosphere. Samplers were deployed in continuous stirred tank reactors (CSTR) and at field sites across a nitrogen deposition gradient in Southern California. Filters were exposed over a four week period with individual filters being subjected to 1-4 week exposure times. Extracted nitric acid were measured for δ18O and δ15N ratios and compared for consistency based on length of exposure and amount of HNO3 collected. Filters within the CSTRs collected HNO3 at a consistent rate in both high and low concentration chambers. After two weeks of exposure, the mean δ18O values were within 0.5‰ of the δ18O of the source HNO3 solution. The mean of all weekly exposures were within 0.5‰ of the δ15N of the source solution, but after three weeks, the mean δ15N of adsorbed HNO3 was within 0.2‰. As the length of the exposure increased, the variability of measured delta values decreased for both elements. The field samplers collected HNO3 consistent with previously measured values along a deposition gradient. The mean δ18O at high deposition sites was 52.2‰ compared to 35.7‰ at the low deposition sites. Mean δ15N values were similar at all sites across the deposition gradient. Due to precipitation events occurring during the exposure period, the δ15N and δ18O of nitric acid were highly variable at all field sites. At single sites, changes in δ15N and δ18O were negatively correlated, consistent with two-sourcing mixing dynamics, but the slope of the regressions differed between high and low deposition sites. Anthropogenic

  11. Water vapor diffusion membranes, 2

    NASA Technical Reports Server (NTRS)

    Holland, F. F.; Klein, E.; Smith, J. K.; Eyer, C.

    1976-01-01

    Transport mechanisms were investigated for the three different types of water vapor diffusion membranes. Membranes representing porous wetting and porous nonwetting structures as well as dense diffusive membrane structures were investigated for water permeation rate as a function of: (1) temperature, (2) solids composition in solution, and (3) such hydrodynamic parameters as sweep gas flow rate, solution flow rate and cell geometry. These properties were measured using nitrogen sweep gas to collect the effluent. In addition, the chemical stability to chromic acid-stabilized urine was measured for several of each type of membrane. A technology based on the mechanism of vapor transport was developed, whereby the vapor diffusion rates and relative susceptibility of membranes to fouling and failure could be projected for long-term vapor recovery trials using natural chromic acid-stabilized urine.

  12. Temporal variation in daily concentrations of ozone and acid-related substances at Saturna Island, British Columbia.

    PubMed

    Vingarzan, Roxanne; Thomson, Bruce

    2004-04-01

    A multiple linear regression model was used to investigate seasonal and long-term trends in concentrations of ozone (O3) and acid-related substances at the Saturna Island monitoring station in southwestern British Columbia from 1991 to 2000. Statistically significant primary (dominant) cycles with a period of 1 yr were found for O3, sulfur dioxide (SO2), nitric acid (HNO3), and aerosol concentrations of sulfate (SO4(2-)), calcium (Ca2+) and chloride (Cl-). Of these, peak median concentrations occurred during the spring for O3 and Ca2+, during the warmer, drier months (April-September) for SO4(2-) and HNO3, and during the cooler, wetter months (October-March) for SO2 and Cl-. Statistically significant secondary cycles of 6 months duration were seen for concentrations of O3, SO4(2-), HNO3, Ca2+, and Cl-. Daily maximum O3 concentrations exhibited a statistically significant increase over the period of record of 0.33 +/- 0.26 ppb/yr. Statistically significant declines were found for concentrations of SO2, SO4(2-), HNO3, Ca2+, and potassium, ranging from 20 to 36% from levels at the start of the sampling period. Declines in ambient concentrations of SO2, SO4(2-), and HNO3 reflect local declines in anthropogenic emissions of the primary precursors SO2 and NOx over the past decade. Trends in Ca2+ and potassium ion concentrations are in line with a broader North American declining trend in acid-neutralizing cations.

  13. Sulfuric acid vapor in the atmosphere of Venus as observed by the Venus Express Radio Science experiment VeRa

    NASA Astrophysics Data System (ADS)

    Oschlisniok, Janusz; Pätzold, Martin; Häusler, Bernd; Tellmann, Silvia; Bird, Mike; Andert, Tom

    2016-04-01

    The cloud deck within Venus' atmosphere, which covers the entire planet between approx. 50 and 70 km altitude, consists mostly of liquid and gaseous sulfuric acid. The gaseous part increases strongly just below the main clouds and builds an approx. 15 km thick haze layer of H2SO4. This region is responsible for a strong absorption of radio waves as seen in VeRa radio science observations. The amount of the absorption, which is used to derive the abundance of gaseous sulfuric acid, depends on the signal frequency. VeRa probed the atmosphere of Venus between 2006 and 2015 with radio signals at 13 cm (S-band) and 3.6 cm (X-band) wavelengths. We present H2SO4 profiles derived from S-band and X-band absorption during the first occultation season in 2006. The comparison of the H2SO4 profiles derived from both frequency bands provides a reliable picture of the H2SO4 abundance. Distinct differences in the S- and X-band profiles may give a clue to increased SO2 abundances. The derived VeRa results shall be compared with results provided by other experiments onboard Venus Express as well as with previous missions.

  14. Quantitative analysis of mixed hydrofluoric and nitric acids using Raman spectroscopy with partial least squares regression.

    PubMed

    Kang, Gumin; Lee, Kwangchil; Park, Haesung; Lee, Jinho; Jung, Youngjean; Kim, Kyoungsik; Son, Boongho; Park, Hyoungkuk

    2010-06-15

    Mixed hydrofluoric and nitric acids are widely used as a good etchant for the pickling process of stainless steels. The cost reduction and the procedure optimization in the manufacturing process can be facilitated by optically detecting the concentration of the mixed acids. In this work, we developed a novel method which allows us to obtain the concentrations of hydrofluoric acid (HF) and nitric acid (HNO(3)) mixture samples with high accuracy. The experiments were carried out for the mixed acids which consist of the HF (0.5-3wt%) and the HNO(3) (2-12wt%) at room temperature. Fourier Transform Raman spectroscopy has been utilized to measure the concentration of the mixed acids HF and HNO(3), because the mixture sample has several strong Raman bands caused by the vibrational mode of each acid in this spectrum. The calibration of spectral data has been performed using the partial least squares regression method which is ideal for local range data treatment. Several figures of merit (FOM) were calculated using the concept of net analyte signal (NAS) to evaluate performance of our methodology.

  15. Quantitative analysis of mixed hydrofluoric and nitric acids using Raman spectroscopy with partial least squares regression.

    PubMed

    Kang, Gumin; Lee, Kwangchil; Park, Haesung; Lee, Jinho; Jung, Youngjean; Kim, Kyoungsik; Son, Boongho; Park, Hyoungkuk

    2010-06-15

    Mixed hydrofluoric and nitric acids are widely used as a good etchant for the pickling process of stainless steels. The cost reduction and the procedure optimization in the manufacturing process can be facilitated by optically detecting the concentration of the mixed acids. In this work, we developed a novel method which allows us to obtain the concentrations of hydrofluoric acid (HF) and nitric acid (HNO(3)) mixture samples with high accuracy. The experiments were carried out for the mixed acids which consist of the HF (0.5-3wt%) and the HNO(3) (2-12wt%) at room temperature. Fourier Transform Raman spectroscopy has been utilized to measure the concentration of the mixed acids HF and HNO(3), because the mixture sample has several strong Raman bands caused by the vibrational mode of each acid in this spectrum. The calibration of spectral data has been performed using the partial least squares regression method which is ideal for local range data treatment. Several figures of merit (FOM) were calculated using the concept of net analyte signal (NAS) to evaluate performance of our methodology. PMID:20441916

  16. A broadband cavity enhanced absorption spectrometer for aircraft measurements of glyoxal, methylglyoxal, nitrous acid, nitrogen dioxide, and water vapor

    NASA Astrophysics Data System (ADS)

    Min, K.-E.; Washenfelder, R. A.; Dubé, W. P.; Langford, A. O.; Edwards, P. M.; Zarzana, K. J.; Stutz, J.; Lu, K.; Rohrer, F.; Zhang, Y.; Brown, S. S.

    2016-02-01

    We describe a two-channel broadband cavity enhanced absorption spectrometer (BBCEAS) for aircraft measurements of glyoxal (CHOCHO), methylglyoxal (CH3COCHO), nitrous acid (HONO), nitrogen dioxide (NO2), and water (H2O). The instrument spans 361-389 and 438-468 nm, using two light-emitting diodes (LEDs) and a single grating spectrometer with a charge-coupled device (CCD) detector. Robust performance is achieved using a custom optical mounting system, high-power LEDs with electronic on/off modulation, high-reflectivity cavity mirrors, and materials that minimize analyte surface losses. We have successfully deployed this instrument during two aircraft and two ground-based field campaigns to date. The demonstrated precision (2σ) for retrievals of CHOCHO, HONO and NO2 are 34, 350, and 80 parts per trillion (pptv) in 5 s. The accuracy is 5.8, 9.0, and 5.0 %, limited mainly by the available absorption cross sections.

  17. A broadband cavity enhanced absorption spectrometer for aircraft measurements of glyoxal, methylglyoxal, nitrous acid, nitrogen dioxide, and water vapor

    NASA Astrophysics Data System (ADS)

    Min, K.-E.; Washenfelder, R. A.; Dubé, W. P.; Langford, A. O.; Edwards, P. M.; Zarzana, K. J.; Stutz, J.; Lu, K.; Rohrer, F.; Zhang, Y.; Brown, S. S.

    2015-10-01

    We describe a two-channel broadband cavity enhanced absorption spectrometer (BBCEAS) for aircraft measurements of glyoxal (CHOCHO), methylglyoxal (CH3COCHO), nitrous acid (HONO), nitrogen dioxide (NO2), and water (H2O). The instrument spans 361-389 and 438-468 nm, using two light emitting diodes (LEDs) and a grating spectrometer with a charge-coupled device (CCD) detector. Robust performance is achieved using a custom optical mounting system, high power LEDs with electronic on/off modulation, state-of-the-art cavity mirrors, and materials that minimize analyte surface losses. We have successfully deployed this instrument during two aircraft and two ground-based field campaigns to date. The demonstrated precision (2σ) for retrievals of CHOCHO, HONO and NO2 are 34, 350 and 80 pptv in 5 s. The accuracy is 5.8, 9.0 and 5.0 % limited mainly by the available absorption cross sections.

  18. Effect of acid vapor etching on morphological and opto-electric properties of flat silicon and silicon nanowire arrays: A comparative study

    NASA Astrophysics Data System (ADS)

    Amri, Chohdi; Ouertani, Rachid; Hamdi, Abderrahmen; Ezzaouia, Hatem

    2016-03-01

    In this paper, we report a comparative study between porous silicon (pSi) and porous silicon nanowires (pSiNWs). Acid Vapor Etching (AVE) treatment has been used to perform porous structure on flat Si and SiNWs array substrates respectively. SiNW structure is prepared by the widely used Silver catalyzed etching method. SEM and TEM images show that AVE treatment induces porous structure in the whole Si wafer and the SiNW sidewall. Comparatively to pSi, pSiNWs exhibit a low reflectivity in the whole spectral range which decreases with etching duration. However, the reflectivity of pSi changes with porous layer thickness. Both pSi and pSiNWs exhibit a significant PL peak situated at 2 eV. PL peaks are attributed to the quantum confinement effect in the silicon nanocrystallites (SiNCs). We discussed the significant enhancement in the peak intensities and a shift toward lower energy displayed in Raman spectra for both pSi and pSiNWs. We reported a correlative study of the AVE treatment effect on the minority carrier life time of flat silicon and SiNW arrays with the passivation effect of chemical induced silicon oxides highlighted by FTIR spectra.

  19. Development of a method for total Hg determination in oil samples by cold vapor atomic absorption spectrometry after its extraction induced by emulsion breaking.

    PubMed

    Vicentino, Priscila de O; Brum, Daniel M; Cassella, Ricardo J

    2015-01-01

    This work reports the development of a novel extraction method for total Hg determination in oil samples. After extracting Hg from samples it was quantified in the extracts by cold vapor atomic absorption spectrometry (CV-AAS), employing a laboratory-made gas-liquid separator (GLS) and NaBH4 as reducing agent. The extraction of Hg from samples was carried out by extraction induced by emulsion breaking (EIEB), which is based on the formation and breaking of water-in-oil emulsion between the oil samples and an extractant solution containing an emulsifying agent (surfactant) and nitric acid. Operational parameters of the GLS were evaluated in order to set the best performance of the measurement system. In these studies it was proven that the volume of sample and the concentration of HCl added to the sample extracts had significant influence on Hg response. The best conditions were achieved by adding 0.5 mL of a 0.3 mol L(-1) HCl solution on 1 mL of sample extract. The extraction conditions were also optimized. The highest efficiency was observed when 4 mL of a solution containing 2.5% triton X-100 and 15% v/v HNO3 were employed for the extraction of Hg contained in 20 mL of sample. Emulsion breaking was performed by heating at 80 °C and took approximately 20 min. The limit of quantification of the method was 1.9 µg L(-1) and recovery percentages between 80% and 103% were observed when spiked samples (2 and 10 µg L(-1)) of diesel oil, biodiesel and mineral oil were analyzed.

  20. Influence of gas-particle partitioning on ammonia and nitric acid fluxes above a deciduous forest in the Midwestern USA

    NASA Astrophysics Data System (ADS)

    Hansen, K.; Sørensen, L. L.; Hornsby, K. E.; Boegh, E.; Pryor, S. C.

    2013-12-01

    Quantifying the atmosphere-biosphere exchange of reactive nitrogen gasses (including ammonia (NH3) and nitric acid (HNO3)) is crucial to assessing the impact of anthropogenic activities on natural and semi-natural ecosystems. However, measuring the deposition of reactive nitrogen is challenging due to bi-directionality of the flux, and the dynamics of the chemical gas/aerosol equilibrium of NH3 and HNO3 (or other atmospheric acids) with aerosol-phase ammonium (NH4+) and nitrate (NO3-). NH3 and HNO3 are both very reactive and typically exhibit higher deposition velocities than aerosol NH4+. Therefore, the phase partitioning between gas and aerosol phases can have a significant effect on local budgets and atmospheric transport distances (Nemitz et al., Atmos. Chem. Phys., 2004). In this study, fluxes of NH3, HNO3 and carbon dioxide (CO2) along with size-resolved N-aerosol concentrations are measured above the deciduous forest, Morgan Monroe State Forest (MMSF) in south-central Indiana (39°53'N, 86°25'W) during a field campaign. Two relaxed eddy accumulation (REA) systems are used to measure fluxes and concentrations of NH3 and HNO3 at 44 m. The NH3 REA system operates based on wet effluent diffusion denuders with detection by florescence and half-hourly flux measurements are calculated. HNO3 REA system is based on gas capture on sodium chloride (NaCl) coated denuders with subsequent analysis by ion-chromatography, and the resulting fluxes have a resolution of 3-4 hours. CO2 fluxes are measured by eddy covariance using a closed-path Licor LI-7500, while two MSP MOUDI-110 impactors are used to measure the 24-hourly average inorganic and 48 hourly averaged organic ion concentrations in 11 size bins, respectively, just above the canopy level (28 m). The results of this field campaign are used to quantify the fluxes of NH3, HNO3, CO2 to/from the forest during the transition towards senescence, and to investigate process-level controls (e.g. the role of phase

  1. XPS and STEM studies of Allende acid insoluble residues

    NASA Technical Reports Server (NTRS)

    Housley, R. M.; Clarke, D. R.

    1980-01-01

    Data on Allende acid residues obtained both before and after etching with hot HNO3 are presented. X-ray photoelectron spectra show predominantly carbonaceous material plus Fe-deficient chromite in both cases. The HNO3 oxidizes the carbonaceous material to some extent. The small chromites in these residues have a wide range of compositions somewhat paralleling those observed in larger Allende chromites and in Murchison chromites, especially in the high Al contents; however, they are deficient in divalent cations, which makes them metastable and indicates that they must have formed at relatively low temperatures. It is suggested that they formed by precipitation of Cr(3+) and Fe(3+) from olivine at low temperature or during rapid cooling.

  2. Laboratory measurements of heterogeneous reactions on sulfuric acid surfaces

    NASA Technical Reports Server (NTRS)

    Williams, Leah R.; Manion, Jeffrey A.; Golden, David M.; Tolbert, Margaret A.

    1994-01-01

    Increasing evidence from field, modeling, and laboratory studies suggests that heterogeneous reactions on stratospheric sulfate aerosol particles may contribute to global ozone depletion. Using a Knudsen cell reactor technique, the authors have studied the uptake, reactivity, and solubility of several trace atmospheric species on cold sulfuric acid surfaces representative of stratospheric aerosol particles. The results suggest that the heterogeneous conversion of N2O5 to HNO3 is fast enough to significantly affect the partitioning of nitrogen species in the global stratosphere and thus contribute to global ozone depletion. The hydrolysis of ClONO2 is slower and unlikely to be important under normal conditions at midlatitudes. The solubilities of HCl and HNO3 in sulfuric acid down to 200 K were found to be quite low. For HCl, this means that little HCl is available for reaction on the surfaces of stratospheric sulfate aerosol particles. The low solubility of HNO3 means that this product of heterogeneous reactions will enter the gas phase, and the denitrification observed in polar regions is unlikely to occur in the global stratosphere.

  3. Field method comparison for the characterization of acid aerosols and gases

    NASA Astrophysics Data System (ADS)

    Suh, Helen H.; Allen, George A.; Aurian-Blájeni, Benedict; Koutrakis, Petros; Burton, Robert M.

    This paper presents findings from two intercomparison studies of acid aerosol measurement systems, which were conducted in Uniontown and State College, PA, during the summers of 1990 and 1991, respectively. As part of these studies, acid aerosol and gas concentrations (NH 3, HNO 3, HNO 2, SO 2, H +, NH 4+, NO 3, SO 42-) were measured using five systems: the Harvard/EPA Annular Denuder Systems (HEADS), the Personal Annular Denuder System (PADS), the Continuous Sulfate/Thermal Speciation system (CSTS), the Micro-Orifice Impactor (MOI), and the Harvard Marple Impactor (HI). Concentrations were measured over 3, 12, and 24 h periods, with resultant acid aerosol and gas measurements compared for each system. Results from these studies show excellent agreement among the particulate measurement systems. The sulfate (SO 42-), aerosol strong acidity (H +), and ammonium (NH 4+) concentrations measured by all systems were highly correlated. In addition, 3 and 12 h particulate measurements were comparable for HEADS, MO1, and PADS samplers. Although significantly different, mean relative differences between HEADS measurements and those obtained using the HI and CSTS (SO 42- only) systems were small. For the gases nitric acid (HNO 3) and sulfur dioxide (SO 2), the performance of the HEADS sampler was found to be independent of sample duration, as the 3 and 12 h HEADS measurements were comparable. The PADS sampler, however, was found to measure concentrations of both HNO 3 and SO 2 poorly. PADS measurements, of HNO 3 in particular, were significantly lower than corresponding HEADS measurements. These lower values probably resulted from their deposition on the inlet surfaces of the PADS sampler. The performance of the measurement systems for ammonia (NH 3), nitrous acid (HONO), and nitrate (NO 3-) could not be determined, since their outdoor levels generally were near or below the limit of detection (LOD).

  4. Nitric acid and ammonia emissions from a mid-latitude prescribed wetlands fire

    NASA Technical Reports Server (NTRS)

    Lebel, P. J.; Cofer, W. R., III; Levine, J. S.; Vay, S. A.; Roberts, P. D.

    1988-01-01

    The first simultaneous measurements of gaseous nitric acid and ammonia in the smoke plume of a wetlands biomass burn were obtained. The measurements were made using tungsten oxide-coated diffusion denuder tubes from a helicopter during a prescribed burn on November 9, 1987, at the Merritt Island National Wildlife Refuge, located at the NASA John F. Kennedy Space Center, Florida. The mean NH3 and HNO3 mixing ratios measured in the smoke plume were 19 ppbv and 14 ppbv, respectively, both significantly higher than background mixing ratios. Nitric acid correlated well with carbon dioxide produced by the combustion. The mean CO2-normalized emission ratio for HNO3 was found to be 0.00012. Ammonia, however, dit not correlate well with CO2, suggesting a more complex relationship between combustion and production/release of NH3.

  5. Acid aerosol measurements at a suburban Connecticut site

    NASA Astrophysics Data System (ADS)

    Keeler, Gerald J.; Spengler, John D.; Castillo, Raymond A.

    Atmospheric acidity data were gathered during a year-long field project investigating the possible health effects of acid aerosol in a rural community in southwestern Connecticut. This site was chosen because the air quality is frequently influenced by pollutants transported from the New York-New Jersey corridor as well as from the Midwest U.S. An annular denuder filter-pack system utilized to obtain daily measurements of gaseous HNO 3, HONO, SO 2, and NH 3; plus fine particle SO 42-, NO 3-, and H +. Fine particle mass ( d ⩽ 2.1 μm) and PM10 (particles d ⩽ 10 μm) were also measured. Ozone concentrations and basic meteorological data were also obtained continuously. The atmosphere was acidic with average concentrations of HONO (16 nmol m -3), HNO 3 (42 nmol m -3), and H + (42 nmol m -3), observed from May to September 1988. Atmospheric ammonia concentrations were fairly low averaging 34 nmol m -3 during the same period, and suggesting the neutralizing capacity of the air was significant to neutralize all the acidic species present. Neutralization of acidic particles by reactions on the filter media after collection resulted in a loss of approximately 10% of the measured particle strong acidity for the summertime period investigated. Concentrations of ozone and acidic gases tended to peak with mixed layer flow from the south-southwest while particulate acidity was highest with flow predominantly from the west-soutwest. Hourly ozone concentrations greater than 100 ppb were observed on 31 different days during the monitoring, and concentrations greater than 150 ppb measured on 14 days. HNO 3 and aerosol strong acidity (H +) concentrations reached 174 and 199 nmol m -3, respectively during the summer months.

  6. Heterogeneous reactions of chlorine nitrate and hydrogen chloride on type I polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun; Moore, Steven B.; Keyser, Leon F.

    1991-01-01

    A fast-flow reactor coupled with a quadrupole mass spectrometer was used to study the heterogeneous reactions ClONO2 + HCl yields Cl2 + HNO3 (1) and ClONO2 + H2O yields HOCl + HNO3 (2) on vapor-deposited HNO3-H2O ice substrates. It was found that the sticking coefficient of HCl on these substrates was a strong function of the substrate composition, ranging from about 2 x 10 exp -5 at nitric acid trihydrate composition to 6 x 10 exp -3 at 45 wt pct HNO3. The HNO3-H2O ice substrates were found to have large internal surface areas, and corrections for gas-phase diffusion within the porous ices were applied to observed loss rates.

  7. Heterogeneous conversion of calcite aerosol by nitric acid.

    PubMed

    Preszler Prince, A; Grassian, V H; Kleiber, P; Young, M A

    2007-02-01

    The reaction of nitric acid with calcite aerosol at varying relative humidities has been studied under suspended particle conditions in an atmospheric reaction chamber using infrared absorption spectroscopy. The reactant concentration in the chamber, as well as the appearance of gas phase products and surface adsorbed species, was spectroscopically monitored before and after mixing with CaCO(3) (calcite) particles. The interaction with HNO(3) was found to lead to gas phase CO(2) evolution and increased water uptake due to heterogeneous conversion of the carbonate to particulate nitrate. The reaction was enhanced as the relative humidity of the system was increased, especially at relative humidities above the reported deliquescence point of particulate Ca(NO(3))(2). The measured reaction extent demonstrates that the total calcite particulate mass is available for reaction with HNO(3) and the conversion process is not limited to the particle surface. The spectroscopy of the surface formed nitrate suggests a highly concentrated solution environment with a significant degree of ion pairing. The implications of the HNO(3) loss and the formation of the particulate nitrate product for atmospheric chemistry are discussed. PMID:17242744

  8. Heterogeneous Reactions of ClONO2, HCl, and HOCl on Liquid Sulfuric Acid Surfaces

    NASA Technical Reports Server (NTRS)

    Zhang, Renyi; Leu, Ming-Taun; Keyser, Leon F.

    1994-01-01

    The heterogeneous reactions of ClONO2 + H2O yields HNO3 + HOCl (1), ClONO2 + HCl yields C12 + HNO3 (2), and HOCl + HCl yields Cl2 + H2O (3) on liquid sulfuric acid surfaces have been studied using a fast flow reactor coupled to a quadrupole mass spectrometer. The main objectives of the study are to investigate: (a) the temperature dependence of these reactions at a fixed H2O partial pressure typical of the lower stratosphere (that is, by changing temperature at a constant water partial pressure, the H2SO4 content of the surfaces is also changed), (b) the relative importance or competition between reactions 1 and 2, and (c) the effect of HNO3 on the reaction probabilities due to the formation of a H2SO4/HNO3/H2O ternary system. The measurements show that all the reactions depend markedly on temperature at a fixed H2O partial pressure: they proceed efficiently at temperatures near 200 K and much slower at temperatures near 220 K. The reaction probability (gamma(sub 1)) for ClONO2 hydrolysis approaches 0.01 at temperatures below 200 K, whereas the values for gamma(sub 2) and gamma(sub 3) are on the order of a few tenths at 200 K. Although detailed mechanisms for these reactions are still unknown, the present data indicate that the competition between ClONO2 hydrolysis and ClONO2 reaction with HCl may depend on temperature (or H2SO4 Wt %): in the presence of gaseous HCl at stratospheric concentrations, reaction 2 is dominant at lower temperatures (less than 200 K), but reaction 1 becomes important at temperatures above 210 K. Furthermore, reaction probability measurements performed on the H2SO4/HNO3/ H2O ternary solutions do not exhibit noticeable deviation from those performed on the H2SO4/H2O binary system, suggesting little effect of HNO3 in sulfate aerosols on the ClONO2 and HOCl reactions with HCl. The results reveal that significant reductions in the chlorine-containing reservoir species (such as ClONO2 and HCl) can take place on stratospheric sulfate aerosols at

  9. Long-term variations in abundance and distribution of sulfuric acid vapor in the Venus atmosphere inferred from Pioneer Venus and Magellan radio occultation studies

    NASA Technical Reports Server (NTRS)

    Jenkins, J. M.; Steffes, P. G.

    1992-01-01

    Radio occultation experiments have been used to study various properties of planetary atmospheres, including pressure and temperature profiles, and the abundance profiles of absorbing constituents in those planetary atmospheres. However, the reduction of amplitude data from such experiments to determine abundance profiles requires the application of the inverse Abel transform (IAT) and numerical differentiation of experimental data. These two operations preferentially amplify measurement errors above the true signal underlying the data. A new technique for processing radio occultation data has been developed that greatly reduces the errors in the derived absorptivity and abundance profiles. This technique has been applied to datasets acquired from Pioneer Venus Orbiter radio occultation studies and more recently to experiments conducted with the Magellan spacecraft. While primarily designed for radar studies of the Venus surface, the high radiated power (EIRP) from the Magellan spacecraft makes it an ideal transmitter for measuring the refractivity and absorptivity of the Venus atmosphere by such experiments. The longevity of the Pioneer Venus Orbiter has made it possible to study long-term changes in the abundance and distribution of sulfuric acid vapor, H2SO4(g), in the Venus atmosphere between 1979 and 1992. The abundance of H2SO4(g) can be inferred from vertical profiles of 13-cm absorptivity profiles retrieved from radio occultation experiments. Data from 1979 and 1986-87 suggest that the abundance of H2SO4(g) at latitudes northward of 70 deg decreased over this time period. This change may be due to a period of active volcanism in the late 1970s followed by a relative quiescent period, or some other dynamic process in the Venus atmosphere. While the cause is not certain, such changes must be incorporated into dynamic models of the Venus atmosphere. Potentially, the Magellan spacecraft will extend the results of Pioneer Venus Orbiter and allow the continued

  10. Fourier transform infrared studies of model polar stratospheric cloud surfaces - Growth and evaporation of ice and nitric acid/ice

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Middlebrook, Ann M.

    1990-01-01

    Fourier-transform infrared surface studies are used to probe the microphysical properties of nitric acid trihydrate (NAT) and ice films representative of type I and II polar stratospheric clouds (PSC). Experiments indicate that, on initial exposure to 1.8 microtorr of HNO3, a layer of ice is quantitatively converted to NAT. However, conversion of ice to NAT does not proceed indefinitely, but rather the system reaches saturation. For longer exposures or higher HNO3 pressures, NAM becomes the dominant nitric acid containing species on the surface. Evaporation studies were performed to test the feasibility of a recent denitrification mechanism. The results indicate that ice coated with 0.20 micron of NAT evaporates at a temperature of about 4 C higher than uncoated ice.

  11. [Effect of acid-base two steps surface modification on the adsorption of Cr(VI) onto activated carbon].

    PubMed

    Liu, Shou-xin; Chen, Xiao-yun; Chen, Xi; Sun, Cheng-lin

    2005-11-01

    Effect of HNO3-NaOH two steps surface modification on the adsorption of Cr(VI) from aqueous solution onto activated carbon was evaluated. Activated carbon was oxidized in HNO3 aqueous solution at first (AC1), then treated in the mixture of NaOH and NaCl solution (AC2). Batch equilibrium and continuous adsorption experiments were conducted to determine the adsorption characteristics. Boehm titration method, element analysis were used to characterize the surface properties. N2/77 K adsorption isotherm method was used to characterize the pore structure. The results reveal that adsorption capacity and adsorption rate increase significantly, which in the following order: AC2>AC1>AC0. Surface modification caused BET surface area decreased and the total number of surface oxygen acid groups increased. First oxidation modification in HNO3 solution produced positive acid groups on the surface of activated carbon. Subsequent 2nd modification replaced H+ of carbon surface groups by Na+, the acidity of AC2 was decreased. The main cause of higher Cr(VI) adsorption capacity and rate for AC2 was the more oxygen surface acid groups, and suitable solution pH provide by surface groups.

  12. Calibrated vapor generator source

    DOEpatents

    Davies, J.P.; Larson, R.A.; Goodrich, L.D.; Hall, H.J.; Stoddard, B.D.; Davis, S.G.; Kaser, T.G.; Conrad, F.J.

    1995-09-26

    A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet. 10 figs.

  13. Calibrated vapor generator source

    DOEpatents

    Davies, John P.; Larson, Ronald A.; Goodrich, Lorenzo D.; Hall, Harold J.; Stoddard, Billy D.; Davis, Sean G.; Kaser, Timothy G.; Conrad, Frank J.

    1995-01-01

    A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet.

  14. Ultrafine aerosol size distributions and sulfuric acid vapor pressures: Implications for new particle formation in the atmosphere. Year 2 progress report

    SciTech Connect

    McMurry, P.H.

    1993-07-01

    This project has two components: (1) measurement of H{sub 2}SO{sub 4} vapor pressures in air under temperature/relative humidity conditions similar to atmospheric, and (2) measurement of ultrafine aerosol size distributions. During Year 2, more effort was put on size distribution measurements. 4 figs.

  15. Wintertime nitric acid chemistry - Implications from three-dimensional model calculations

    NASA Technical Reports Server (NTRS)

    Rood, Richard B.; Kaye, Jack A.; Douglass, Anne R.; Allen, Dale J.; Steenford, Stephen

    1990-01-01

    A three-dimensional simulation of the evolution of HNO3 has been run for the winter of 1979. Winds and temperatures are taken from a stratospheric data assimilation analysis, and the chemistry is based on Limb Infrared Monitor of the Stratosphere (LIMS) observations. The model is compared to LIMS observations to investigate the problem of 'missing' nitric acid chemistry in the winter hemisphere. Both the model and observations support the contention that a nitric acid source is needed outside of the polar vortex and north of the subtropics. Observations suggest that HNO3 is not dynamically controlled in middle latitudes. The model shows that given the time scales of conventional chemistry, dynamical control is expected. Therefore, an error exists in the conventional chemistry or additional processes are needed to bring the model and data into agreement. Since the polar vortex is dynamically isolated from the middle latitudes, and since the highest HNO3 values are observed in October and November, a source associated solely with polar stratospheric clouds cannot explain the deficiencies in the chemistry. The role of heterogeneous processes on background aerosols is reviewed in light of these results.

  16. Laboratory studies of potential mechanisms of renoxification of tropospheric nitric acid.

    PubMed

    Rivera-Figueroa, A M; Sumner, A L; Finlayson-Pitts, B J

    2003-02-01

    Laboratory studies of the heterogeneous reactions between HNO3 in thin water films on silica surfaces and gaseous NO, CO, CH4, and SO2, proposed as potential "renoxification" mechanisms in the atmosphere, are reported. Transmission FTIR was used to monitor reactants and products on the silica surface and in the gas phase as a function of time. No reaction of CO, CH4, or SO2 was observed; upper limits to the reaction probabilities (gamma(rxn)) are < or = 10(-10) for CO and SO2 and < or = 10(-12) for CH4. However, the reaction of HNO3 with NO does occur with a lower limit for the reaction probability of gammaNO > or = (6 +/- 2) x 10(-9) (2s). The experimental evidence shows that the chemistry is insensitive to whether the substrate is pure silica or borosilicate glass. Nitric acid in its molecular form, and not the nitrate anion form, was shown to be the reactive species, and NH4NO3 was shown not to react with NO. The HNO3-NO reaction could be a significant means of renoxification of nitric acid on the surfaces of buildings and soils in the boundary layer of polluted urban atmospheres. This chemistry may help to resolve some discrepancies between model-predicted ozone and field observations in polluted urban atmospheres.

  17. Interactions of Gas-Phase Nitric/Nitrous Acids and Primary Organic Aerosol in the Atmosphere of Houston, TX

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Griffin, R. J.; Dibb, J. E.; Anderson, C. H.; Whitlow, S. I.; Lefer, B. L.; Flynn, J.; Rappenglück, B.

    2007-12-01

    Concentrations of aerosol and gas-phase pollutants were measured on the roof of an 18-story building during the Texas Air Quality Study II Radical and Aerosol Measurement Project (TRAMP) from August 15 through September 28, 2006. Aerosol measurements included size-resolved, non-refractory mass concentrations of ammonium, nitrate, sulfate, chloride, and organic aerosol in submicron particles using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS). Particulate water-soluble organic carbon (PWSOC) was quantified using a mist chamber/total organic carbon analysis system. Concentration data for gas-phase pollutants included those for nitric acid (HNO3), nitrous acid (HONO), and hydrochloric acid (HCl) collected using a mist chamber/ion chromatographic technique, oxides of nitrogen (NOx) collected using a chemiluminescent method, and carbon monoxide (CO) collected using an infrared gas correlation wheel instrument. Coincident increases in nitrate and organic aerosol mass concentrations were observed on many occasions throughout the measurement campaign, most frequently during the morning rush hour. Based on the lack of organic aerosol processing (defined by the ratio of m/z = 44/57 in the Q-AMS spectra), strong correlation with NOx and CO, and a lack of significant increase in PWSOC concentration, the spikes in organic aerosol were likely associated with primary organic aerosol (POA). During these events, gas-phase HNO3 concentration decreases were observed simultaneously with increases in gas-phase HONO concentrations. These data likely indicate uptake of HNO3 and subsequent heterogeneous conversion to HONO involving POA. Preliminary calculations show that HNO3 partitioning could account for the majority of the observed HONO and aerosol nitrate concentrations during these events. Q-AMS chloride and HCl data also indicate uptake of chloride by particles during these events. This phenomenon was also observed during the night, but these nocturnal events were less

  18. The Effects of Gaseous Ozone and Nitric Acid Deposition on two Crustose Lichen Species From Joshua Tree National Park

    NASA Astrophysics Data System (ADS)

    Hessom, Elizabeth Curie

    Lichens are dependent on atmospheric deposition for much of their water and nutrients, and due to their sensitivity to pollutants, are commonly used as bioindicators for air quality. While studies have focused on epiphytic (tree dwelling) lichens as bioindicators, virtually nothing is known about crustose (rock dwelling) lichens. The atmospheric pollutants ozone (O 3) and nitric acid (HNO3) are two major pollutants found within the Los Angeles Basin. While recent O3 research suggests it does not significantly affect lichen growth, HNO3 appears to be phytotoxic to some lichens. As both of these pollutants are deposited downwind from the L.A. basin into Joshua Tree National Park (JOTR), lichen species located in the park may provide a sensitive indicator of pollution effects. This research studied two lichen species of particular interest from Joshua Tree National Park, Lobothallia praeradiosa (Nyl.) Hafellner, and Acarospora socialis H. Magn., both of which are crustose species with unknown sensitivities to O3, as well as hypothesized and unknown sensitivities to nitrogen compounds, respectively. Little research exists for either species, possibly because of the difficulty in working with crustose lichens. This research attempted to expand the background knowledge of these species by exposing them to varying levels of O3 and HNO3, to ascertain their physiological responses. Physiological measures of chlorophyll fluorescence, dark respiration, microscopic imaging, and lichen washes (as a proxy for membrane leakage), were measured throughout the exposure period. Results indicated that both species had similar sensitivities to O3 and HNO3. Both species registered physical damage during the O3 fumigation, as well as a decrease in respiration. Neither species showed major physical damage to HNO3, but both manifested a decrease in chlorophyll fluorescence, suggesting damage to the photosynthetic systems of the algae symbiont. These results suggest that both of these

  19. Double liquid membrane system for the removal of actinides and lanthanides from acidic nuclear wastes

    SciTech Connect

    Chiarizia, R.; Danesi, P.R.

    1987-01-01

    Supported liquid membranes (SLM), consisting of an organic solution of n-octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and tributyl-phosphate (TBP) in decalin are able to perform selective separation and concentration of actinide and lanthanide ions from aqueous nitrate feed solutions and synthetic nuclear wastes. In the membrane process a possible strip solution is a mixture of formic acid and hydroxylammonium formate (HAF). The effectiveness of this strip solution is reduced and eventually nullified by the simultaneous transfer through the SLM of HNO3 which accumulates in the strip solution. A possible way to overcome this drawback is to make use of a second SLM consisting of a primary amine which is able to extract only HNO3 from the strip solution. In this work the results obtained by experimentally studying the membrane system: synthetic nuclear waste/CMPO-TBP membrane/HCOOH-HAF strip solution/primary amine membrane/NaOH solution, are reported. They show that the use of a second liquid membrane is effective in controlling the HNO3 concentration in the strip solution, thus allowing the actinide and lanthanide ions removal from the feed solution to proceed to completion.

  20. High-quality, 2-inch-diameter m-plane GaN substrates grown by hydride vapor phase epitaxy on acidic ammonothermal seeds

    NASA Astrophysics Data System (ADS)

    Tsukada, Yusuke; Enatsu, Yuuki; Kubo, Shuichi; Ikeda, Hirotaka; Kurihara, Kaori; Matsumoto, Hajime; Nagao, Satoru; Mikawa, Yutaka; Fujito, Kenji

    2016-05-01

    In this paper, we discusse the origin of basal-plane stacking faults (BSFs) generated in the homoepitaxial hydride vapor phase epitaxy (HVPE) growth of m-plane gallium nitride (GaN). We investigated the effects of seed quality, especially dislocation density, on BSF generation during homoepitaxy. The results clearly identify basal-plane dislocation in the seed as a cause of BSF generation. We realized high-quality m-plane GaN substrates with a 2-in. diameter using HVPE on low-dislocation-density m-plane seeds.

  1. Application of hydrocyanic acid vapor generation via focused microwave radiation to the preparation of industrial effluent samples prior to free and total cyanide determinations by spectrophotometric flow injection analysis.

    PubMed

    Quaresma, Maria Cristina Baptista; de Carvalho, Maria de Fátima Batista; Meirelles, Francis Assis; Santiago, Vânia Maria Junqueira; Santelli, Ricardo Erthal

    2007-02-01

    A sample preparation procedure for the quantitative determination of free and total cyanides in industrial effluents has been developed that involves hydrocyanic acid vapor generation via focused microwave radiation. Hydrocyanic acid vapor was generated from free cyanides using only 5 min of irradiation time (90 W power) and a purge time of 5 min. The HCN generated was absorbed into an accepting NaOH solution using very simple glassware apparatus that was appropriate for the microwave oven cavity. After that, the cyanide concentration was determined within 90 s using a well-known spectrophotometric flow injection analysis system. Total cyanide analysis required 15 min irradiation time (90 W power), as well as chemical conditions such as the presence of EDTA-acetate buffer solution or ascorbic acid, depending on the effluent to be analyzed (petroleum refinery or electroplating effluents, respectively). The detection limit was 0.018 mg CN l(-1) (quantification limit of 0.05 mg CN l(-1)), and the measured RSD was better than 8% for ten independent analyses of effluent samples (1.4 mg l(-1) cyanide). The accuracy of the procedure was assessed via analyte spiking (with free and complex cyanides) and by performing an independent sample analysis based on the standard methodology recommended by the APHA for comparison. The sample preparation procedure takes only 10 min for free and 20 min for total cyanide, making this procedure much faster than traditional methodologies (conventional heating and distillation), which are time-consuming (they require at least 1 h). Samples from oil (sour and stripping tower bottom waters) and electroplating effluents were analyzed successfully. PMID:17143595

  2. Application of hydrocyanic acid vapor generation via focused microwave radiation to the preparation of industrial effluent samples prior to free and total cyanide determinations by spectrophotometric flow injection analysis.

    PubMed

    Quaresma, Maria Cristina Baptista; de Carvalho, Maria de Fátima Batista; Meirelles, Francis Assis; Santiago, Vânia Maria Junqueira; Santelli, Ricardo Erthal

    2007-02-01

    A sample preparation procedure for the quantitative determination of free and total cyanides in industrial effluents has been developed that involves hydrocyanic acid vapor generation via focused microwave radiation. Hydrocyanic acid vapor was generated from free cyanides using only 5 min of irradiation time (90 W power) and a purge time of 5 min. The HCN generated was absorbed into an accepting NaOH solution using very simple glassware apparatus that was appropriate for the microwave oven cavity. After that, the cyanide concentration was determined within 90 s using a well-known spectrophotometric flow injection analysis system. Total cyanide analysis required 15 min irradiation time (90 W power), as well as chemical conditions such as the presence of EDTA-acetate buffer solution or ascorbic acid, depending on the effluent to be analyzed (petroleum refinery or electroplating effluents, respectively). The detection limit was 0.018 mg CN l(-1) (quantification limit of 0.05 mg CN l(-1)), and the measured RSD was better than 8% for ten independent analyses of effluent samples (1.4 mg l(-1) cyanide). The accuracy of the procedure was assessed via analyte spiking (with free and complex cyanides) and by performing an independent sample analysis based on the standard methodology recommended by the APHA for comparison. The sample preparation procedure takes only 10 min for free and 20 min for total cyanide, making this procedure much faster than traditional methodologies (conventional heating and distillation), which are time-consuming (they require at least 1 h). Samples from oil (sour and stripping tower bottom waters) and electroplating effluents were analyzed successfully.

  3. Structure of a microbial community in soil after prolonged addition of low levels of simulated acid rain

    PubMed

    Pennanen; Fritze; Vanhala; Kiikkila; Neuvonen; Baath

    1998-06-01

    Humus samples were collected 12 growing seasons after the start of a simulated acid rain experiment situated in the subarctic environment. The acid rain was simulated with H2SO4, a combination of H2SO4 and HNO3, and HNO3 at two levels of moderate acidic loads close to the natural anthropogenic pollution levels of southern Scandinavia. The higher levels of acid applications resulted in acidification, as defined by humus chemistry. The concentrations of base cations decreased, while the concentrations of exchangeable H+, Al, and Fe increased. Humus pH decreased from 3.83 to 3.65. Basal respiration decreased with decreasing humus pH, and total microbial biomass, measured by substrate-induced respiration and total amount of phospholipid fatty acids (PLFA), decreased slightly. An altered PLFA pattern indicated a change in the microbial community structure at the higher levels of acid applications. In general, branched fatty acids, typical of gram-positive bacteria, increased in the acid plots. PLFA analysis performed on the bacterial community growing on agar plates also showed that the relative amount of PLFA specific for gram-positive bacteria increased due to the acidification. The changed bacterial community was adapted to the more acidic environment in the acid-treated plots, even though bacterial growth rates, estimated by thymidine and leucine incorporation, decreased with pH. Fungal activity (measured as acetate incorporation into ergosterol) was not affected. This result indicates that bacteria were more affected than fungi by the acidification. The capacity of the bacterial community to utilize 95 different carbon sources was variable and only showed weak correlations to pH. Differences in the toxicities of H2SO4 and HNO3 for the microbial community were not found.

  4. Immobilization of EAFD heavy metals using acidic materials.

    PubMed

    Mitrakas, Manassis G; Sikalidis, Constantinos A; Karamanli, Theoktisti P

    2007-03-01

    This study was undertaken to determine the chemical and leaching characteristics of the Electric Arc Furnace Dust (EAFD) generated by a Greek plant and to investigate various acidic materials efficiency on the EAFD stabilization. In order to investigate how [OH(-)] neutralization influences EAFD heavy metals leachability, Na HCO3(-), HNO3 and H3PO4 were used as acidic materials. The concentration of Pb in leachate was found between 40 and 3.7 x 10(3) mg Pb/kg of EAFD, exceeding in all EAFD samples the maximum acceptable limit (MAL) 25 mg/kg for landfill disposal. Neutralization of [OH(-)] with HCO3(-) decreased Pb concentration in leachate at 350 mg Pb/kg of EAFD, while excess over a stoichiometry in HCO3(-) addition increased leachability of Pb, Cd, Cr, Cu as well as F. Using HNO3 as an acidic material decreased leachability of almost all the parameters concerning the EC directive 33/19-01-2003 in a pH value up to 7.2, in exception of Zn. Zinc leachability showed a U shape curve as a function of pH value. The concentration of Zn was minimized in a concentration lower than 1 mg Zn/kg EAFD in a pH range 10.5 to 9 and exceeded the MAL 90 mg/kg at a pH value 7.2. However, the major disadvantage of HNO3 was proved to be its leachability, since NO3(-) concentration in leachate was equal to HNO3 dose. H3PO4 was found the most promising acidic material for the chemical immobilization of heavy metals, since it decreased their leachability in a concentration significantly lower than MAL at a pH value up to 7.1. Finally, the concentration of Cl(-) ranged between 18 and 33 x 10(3) mg Cl(-)/kg EAFD exceeding in all EAFD samples the MAL 17 x 10(3) mg/kg. This high concentration of Cl(-) is attributed to the scrap and it could be reduced only by modification of its composition.

  5. The renal response to chronic mineral acid feeding: a re-examination of the role of systemic pH.

    PubMed

    Madias, N E; Zelman, S J

    1986-03-01

    It has been widely held that systemic acidemia represents the proximate event signaling the kidney to elicit its acidification response to chronic metabolic acidosis. However, a previous study from this laboratory has cast serious doubt on the validity of this conventional viewpoint. When a large acid load (7 mEq/kg/day) was fed chronically to dogs as HCl, H2SO4 or HNO3, net acid excretion increased similarly in all three groups of animals despite wide variability in the prevailing systemic acid-base composition. Marked or moderate hypobicarbonatemia and acidemia were observed in the HCl- or H2SO4-fed animals respectively, but strikingly, plasma [HCO3-] and pH did not change significantly from the control in the HNO3-fed animals. That study concluded that the renal response to chronic mineral acid feeding appears to be triggered, not by acidemia, but by the interplay of sodium delivery to and sodium avidity of the distal nephron as modulated by the reabsorbability of the "acid" anion. We have re-examined the above provocative conclusion in the light of the observation that the only evidence for a dissociation of the renal response from systemic acidemia in that study was derived from preprandial (8:00 a.m.) blood samples obtained some 23 hr after the ingestion of the daily acid load (administered at 9:00 a.m.). We investigated the diurnal variation of plasma acid-base composition in two groups of dogs fed chronically a large acid load (7 mEq/kg/day) as either HCl or HNO3. Both groups exhibited significant diurnal oscillations of plasma acid-base composition.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3009955

  6. Evaluation of oxygen pressurized microwave-assisted digestion of botanical materials using diluted nitric acid.

    PubMed

    Bizzi, Cezar Augusto; Barin, Juliano Smanioto; Müller, Edson Irineu; Schmidt, Lucas; Nóbrega, Joaquim A; Flores, Erico Marlon Moraes

    2011-02-15

    The feasibility of diluted nitric acid solutions for microwave-assisted decomposition of botanical samples in closed vessels was evaluated. Oxygen pressurized atmosphere was used to improve the digestion efficiency and Al, Ca, K, Fe, Mg and Na were determined in digests by inductively coupled plasma optical emission spectrometry (ICP OES). Efficiency of digestion was evaluated taking into account the residual carbon content (RCC) and residual acidity in digests. Samples were digested using nitric acid solutions (2, 3, 7, and 14 mol L(-1) HNO(3)) and the effect of gas phase composition inside the reaction vessels by purging the vessel with Ar (inert atmosphere, 1 bar), air (20% of oxygen, 1 bar) and pure O(2) (100% of oxygen, 1 bar) was evaluated. The influence of oxygen pressure was studied using pressures of 5, 10, 15 and 20 bar. It was demonstrated that a diluted nitric acid solution as low as 3 mol L(-1) was suitable for an efficient digestion of sample masses up to 500 mg of botanical samples using 5 bar of oxygen pressure. The residual acidities in final digests were lower than 45% in relation to the initial amount of acid used for digestion (equivalent to 1.3 mol L(-1) HNO(3)). The accuracy of the proposed procedure was evaluated using certified reference materials of olive leaves, apple leaves, peach leaves and pine needles. Using the optimized conditions for sample digestion, the results obtained were in agreement with certified values. The limit of quantification was improved up to a factor of 14.5 times for the analytes evaluated. In addition, the proposed procedure was in agreement with the recommendations of the green chemistry once it was possible to obtain relatively high digestion efficiency (RCC<5%) using only diluted HNO(3), which is important to minimize the generation of laboratory residues. PMID:21238716

  7. Vapor spill monitoring method

    DOEpatents

    Bianchini, Gregory M.; McRae, Thomas G.

    1985-01-01

    Method for continuous sampling of liquified natural gas effluent from a spill pipe, vaporizing the cold liquified natural gas, and feeding the vaporized gas into an infrared detector to measure the gas composition. The apparatus utilizes a probe having an inner channel for receiving samples of liquified natural gas and a surrounding water jacket through which warm water is flowed to flash vaporize the liquified natural gas.

  8. Supplemental fuel vapor system

    SciTech Connect

    Foster, P.M.

    1991-01-08

    This patent describes a supplemental fuel system utilizing fuel vapor. It comprises: an internal combustion engine including a carburetor and an intake manifold; a fuel tank provided with air vents; a fuel conduit having a first end connected to the fuel tank and in communication with liquid fuel in the tank and a second end connected to the carburetor; the fuel conduit delivering the liquid fuel to the carburetor from the fuel tank; a fuel vapor conduit having a first end connected to the fuel tank at a location displaced from contact with the liquid fuel and a second end connected to a carbon canister; a PCV conduit having a first end connected to a pollution control valve and a second end connected to the intake manifold; and, an intermediate fuel vapor conduit having a first end connected to the fuel vapor conduit and a second end connected to the PCV conduit; wherein the air vents continuously provide air to the tank to mix with the liquid fuel and form fuel vapor. The fuel vapor drawn from the fuel tank by vacuum developed in the intake manifold and flows through the fuel vapor conduit. The intermediate fuel vapor conduit and the intake manifold to combustion chambers of the internal combustion engine so as to supplement fuel delivered to the engine by the fuel conduit. The liquid fuel and the fuel vapor constantly delivered to the engine during normal operation.

  9. Variational Calculations of IR Ro-Vibrational Spectra for Nitric Acid

    NASA Astrophysics Data System (ADS)

    Pavlyuchko, A. I.; Yurchenko, S. N.; Tennyson, J.

    2013-09-01

    To model the atmospheric composition of the potentially habitable planets, it is essential to have comprehensive data on the spectroscopic properties of the main molecular absorbers. This is especially true in the infrared region which is dominated by transitions of polyatomic molecules [1]. Nitric acid (HNO3) is an important constituent of the Earth atmosphere where it is a prominent bio-signature. Here we present simulations of the absorption spectra for HNO3. We have developed a variational method to solve the ro-vibrational Schrödinger equation for a general polyatomic molecule. The ro-vibrational Hamiltonian is given by [2] where the internal curvilinear vibrational coordinates qi are used to represent the displacements of the bond lengths and bond angles, ?ij(q) are elements of the matrix of the kinematic coefficients, t is the determinant of this matrix, 'a are the Euler angles, and μab(q) is the inverse matrix of the tensor of inertia. The potential energy function, V (q), is given by a fourthorder polynomial expansion in terms of Morse variables xi = 1 - e-iqi for the stretching coordinates and xi = qi for the bending coordinates. The dipole moment of the molecule is presented in the form of a Taylor series of the 2nd order in terms of qi. The parameters of the potential energy and the dipole moment functions of HNO3 were calculated by the quantum chemical method at the CCSD(T)/aug-cc-pVQZ level of theory. With this potential energy function, agreement between the calculated and experimental fundamental frequencies of vibrations is within 5 cm -1. The harmonic part of the potential function was then optimized by fitting to the experimental fundamental frequencies and used to simulate the IR spectra of HNO3. The results are in good agreement with the experimental data. The figure shows an example of the simulated spectra of HNO3 in the area of the strong Fermi resonance between the -5 and 2-9 bands along with an experimental counterpart. The resulting

  10. Petroleum Vapor - Field Technical

    EPA Science Inventory

    The screening approach being developed by EPA OUST to evaluate petroleum vapor intrusion (PVI) requires information that has not be routinely collected in the past at vapor intrusion sites. What is the best way to collect this data? What are the relevant data quality issues and ...

  11. Effects of acid fog and dew on materials. Final report

    SciTech Connect

    Mansfeld, F.; Henry, R.; Vijayakumar, R.

    1989-10-01

    Field exposure tests have been carried out in order to separate the effects of acidic fog on materials damage from those caused by rain, dew and natural weathering. The test sites were McKittrick and Visalia in the Central Valley and West Casitas Pass in Ventura County. The field tests have been supported by laboratory tests in which materials damage has been determined during exposure to carefully controlled fog water chemistry. Analysis of the field exposure results for galvanized steel and the paint samples shows that the corrosivity of the atmosphere at the three test sites have been very low. The result is confirmed by the ACRM data which show very low corrosion activity. Since corrosion rates were so low approaching those for natural weathering, it was not possible to determine the effects of acidic fog. Based on the aerometric data and the observed corrosion behavior, it is doubtful that acidic fog conditions prevailed for significant times during the exposure period of 1/87 - 3/88 at Visalia and McKittrick. The results of the laboratory tests show that exposure to HNO3 at low pH and to high pollutant concentration increased the corrosion rate of galvanized steel to over 10 micro m/year. Exposure to HNO3 caused serious corrosion damage to anodized aluminum and the paint.

  12. Stratospheric water vapor feedback.

    PubMed

    Dessler, A E; Schoeberl, M R; Wang, T; Davis, S M; Rosenlof, K H

    2013-11-01

    We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistry-climate model to be +0.3 W/(m(2)⋅K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126

  13. Stratospheric water vapor feedback

    PubMed Central

    Dessler, A. E.; Schoeberl, M. R.; Wang, T.; Davis, S. M.; Rosenlof, K. H.

    2013-01-01

    We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistry–climate model to be +0.3 W/(m2⋅K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126

  14. Effects of inhalation of acidic compounds on pulmonary function in allergic adolescent subjects.

    PubMed

    Koenig, J Q; Covert, D S; Pierson, W E

    1989-02-01

    There is concern about the human health effects of inhalation of acid compounds found in urban air pollution. It was the purpose of this study to investigate three of these acid compounds, sulfur dioxide (SO2), sulfuric acid (H2SO4), and nitric acid (HNO3) in a group of allergic adolescent subjects. Subjects were exposed during rest and moderate exercise to 0.7 mumole/m3 (68 micrograms/m3) H2SO4, 4.0 mumole/m3 (0.1 ppm) SO2, or 2.0 mumole/m3 (0.05 ppm) HNO3. Pulmonary functions (FEV1, total respiratory resistance, and maximal flow) were measured before and after exposure. Preliminary analysis based on nine subjects indicates that exposure to 0.7 mumole/m3 H2SO4 alone and in combination with SO2 caused significant changes in pulmonary function, whereas exposure to air or SO2 alone did not. FEV1 decreased an average of 6% after exposure to H2SO4 alone and 4% when the aerosol was combined with SO2. The FEV1 decrease was 2% after both air and SO2 exposures. Total respiratory resistance (RT) increased 15% after the combined H2SO4 exposures, 12% after H2SO4 alone, and 7% after exposure to air. After exposures to HNO3 alone, FEV1 decreased by 4%, and RT increased by 23%. These results are preliminary; final conclusions must wait for completion of the study.

  15. Vacuum vapor deposition

    NASA Technical Reports Server (NTRS)

    Poorman, Richard M. (Inventor); Weeks, Jack L. (Inventor)

    1995-01-01

    A method and apparatus is described for vapor deposition of a thin metallic film utilizing an ionized gas arc directed onto a source material spaced from a substrate to be coated in a substantial vacuum while providing a pressure differential between the source and the substrate so that, as a portion of the source is vaporized, the vapors are carried to the substrate. The apparatus includes a modified tungsten arc welding torch having a hollow electrode through which a gas, preferably inert, flows and an arc is struck between the electrode and the source. The torch, source, and substrate are confined within a chamber within which a vacuum is drawn. When the arc is struck, a portion of the source is vaporized and the vapors flow rapidly toward the substrate. A reflecting shield is positioned about the torch above the electrode and the source to ensure that the arc is struck between the electrode and the source at startup. The electrode and the source may be confined within a vapor guide housing having a duct opening toward the substrate for directing the vapors onto the substrate.

  16. Effect of the acidic strength on the vapor phase Beckmann rearrangement of cyclohexanone oxime over the MFI zeolite: an embedded ONIOM study.

    PubMed

    Sirijaraensre, Jakkapan; Limtrakul, Jumras

    2009-01-21

    The mechanism and energetic profile of the Beckmann rearrangement reaction of cyclohexanone oxime to epsilon-caprolactam catalyzed by the H-[Al]-MFI and H-[B]-MFI zeolites were investigated by both the bare cluster and the ONIOM models at the B3LYP/6-31G(d,p) and the B3LYP/6-31G(d,p):MNDO levels of theory, respectively. In order to improve the energetic properties and take into account the whole zeolite framework effect, single point calculations are undertaken at the embedded ONIOM2 schemes; MP2/6-311G(d,p):HF/6-31G(d) with an additional long-range electrostatic potential from the extended zeolite framework. The reaction mechanism of the Beckmann rearrangement over the acid site of zeolites consists of three steps: the 1,2 H shift, the rearrangement and the tautomerization. The activation energies for the Beckmann rearrangement of cyclohexanone oxime on the H-[Al]-MFI zeolite are calculated to be 31.46, 16.15 and 18.95 kcal mol(-1), for the first, second and third steps, respectively, whereas in the H-[B]-MFI zeolite, the energy barriers for each step of the reaction are 24.33, 7.46 and 20.43 kcal mol(-1), respectively. The rate-determining step of the reaction is the first step, which is the transformation from the N-ended cyclohexanone oxime adsorption complex and the O-ended one. These results signify the important role that the acid strength of zeolites plays in altering the energy profile of the reaction. The results further indicate that the weak Brønsted acid sites in the [B]-MFI zeolite could better catalyze the Beckmann rearrangement of cyclohexanone oxime than the strong acid sites in the [Al]-MFI zeolite, as compared with the quantitatively low activation energy of most steps. However, the turnover reaction of the H-[B]-MFI zeolite might be delayed by the quantitatively high desorption energy of the product as compared to the adsorption energy of the reactant.

  17. Solubility and equilibrium vapor pressures of HC1 dissolved in polar stratospheric cloud materials - Ice and the trihydrate of nitric acid

    NASA Technical Reports Server (NTRS)

    Hanson, David; Mauersberger, Konrad

    1988-01-01

    Measurements of the pressure-solubility behavior of HC1 in water ice and in the nitric acid trihydrate (NAT) crystal at 200 K are reported. It was found that HC1 is about 20 times more soluble in NAT than in ice for stratospheric conditions. A relation between HC1 pressure and substrate composition based on the Gibbs-Duhem equation is developed. This relation, along with other thermodynamic data, can be used to obtain the HC1 pressure-solubility behavior at different temperatures. Implications of these results for the south polar ozone hole are discussed.

  18. Formation of stratospheric nitric acid by a hydrated ion cluster reaction: chemical and dynamical effects of energetic particle precipitation on the middle atmosphere

    NASA Astrophysics Data System (ADS)

    Kvissel, O. K.; Orsolini, Y. J.; Stordal, F.

    2012-04-01

    In order to Improve our understanding of the effects of energetic particle precipitation upon the nitrogen family (NOy) and ozone (O3), we have modelled the chemical and dynamical middle atmosphere response to the introduction of a chemical pathway that produces nitric acid (HNO3) by conversion of dinitrogen pentoxide (N2O5) upon hydrated water clusters H+•(H2O)n. We have used an ensemble of simulations with the National Center for Atmospheric Research (NCAR) Whole-Atmosphere Community Climate Model (WACCM) chemistry-climate model. The introduced chemical pathway alters the internal partitioning of NOy during winter months in both hemispheres, and ultimately triggers statistically significant changes in the climatological distributions of constituents including: i) a cold season production of HNO3 with a corresponding loss of N2O5, and ii) a cold season decrease in NOx/NOy-ratio and an increase of O3, in polar regions. We see an improved seasonal evolution of modelled HNO3 compared to satellite observations from Microwave Limb Sounder (MLS), albeit not enough HNO3 is produced at high altitudes. Through O3 changes, both temperature and dynamics are affected, allowing for complex chemical-dynamical feedbacks beyond the cold season when the introduced pathway is active. Hence, we also find a NOx polar increase in spring-to-summer in the SH, and in spring in the NH. The springtime NOx increase arises from anomalously strong poleward transport associated with a weaker polar vortex. In the southern hemisphere, a statistical significant weakening of the stratospheric jet is altered down to the lower stratosphere, and we argue that it is caused by strengthened planetary waves induced by mid-latitude zonal asymmetries in O3 and short-wave heating.

  19. Vapor generator wand

    NASA Technical Reports Server (NTRS)

    Robelen, David B. (Inventor)

    1996-01-01

    A device for producing a stream of vapor for wind tunnel airflow visualization is described. An electrically conductive heating tube is used to resistively heat a vapor producing liquid. The heating and delivery systems are integrated to allow the device to present a small cross section to the air flow, thereby reducing disturbances due to the device. The simplicity of the design allows for inexpensive implementation and construction. The design is readily scaled for use in various wind tunnel applications. The device may also find uses in manufacturing, producing a vapor for deposition on a substrate.

  20. Vapor resistant arteries

    NASA Technical Reports Server (NTRS)

    Shaubach, Robert M. (Inventor); Dussinger, Peter M. (Inventor); Buchko, Matthew T. (Inventor)

    1989-01-01

    A vapor block resistant liquid artery structure for heat pipes. A solid tube artery with openings is encased in the sintered material of a heat pipe wick. The openings are limited to that side of the artery which is most remote from the heat source. The liquid in the artery can thus exit the artery through the openings and wet the sintered sheath, but vapor generated at the heat source is unlikely to move around the solid wall of the artery and reverse its direction in order to penetrate the artery through the openings. An alternate embodiment uses finer pore size wick material to resist vapor entry.

  1. Influence of crustal dust and sea spray supermicron particle concentrations and acidity on inorganic NO3− aerosol during the 2013 Southern Oxidant and Aerosol Study

    DOE PAGES

    Allen, H. M.; Draper, D. C.; Ayres, B. R.; Ault, A.; Bondy, A.; Takahama, S.; Modini, R. L.; Baumann, K.; Edgerton, E.; Knote, C.; et al

    2015-09-25

    Inorganic aerosol composition was measured in the southeastern United States, a region that exhibits high aerosol mass loading during the summer, as part of the 2013 Southern Oxidant and Aerosol Study (SOAS) campaign. Measurements using a Monitor for AeRosols and GAses (MARGA) revealed two periods of high aerosol nitrate (NO3−) concentrations during the campaign. These periods of high nitrate were correlated with increased concentrations of supermicron crustal and sea spray aerosol species, particularly Na+ and Ca2+, and with a shift towards aerosol with larger (1 to 2.5 μm) diameters. We suggest this nitrate aerosol forms by multiphase reactions of HNO3more » and particles, reactions that are facilitated by transport of crustal dust and sea spray aerosol from a source within the United States. The observed high aerosol acidity prevents the formation of NH4NO3, the inorganic nitrogen species often dominant in fine-mode aerosol at higher pH. In addition, calculation of the rate of the heterogeneous uptake of HNO3 on mineral aerosol supports the conclusion that aerosol NO3− is produced primarily by this process, and is likely limited by the availability of mineral cation-containing aerosol surface area. Modeling of NO3− and HNO3 by thermodynamic equilibrium models (ISORROPIA II and E-AIM) reveals the importance of including mineral cations in the southeastern United States to accurately balance ion species and predict gas–aerosol phase partitioning.« less

  2. Speciation in aqueous solutions of nitric acid.

    PubMed

    Hlushak, S; Simonin, J P; De Sio, S; Bernard, O; Ruas, A; Pochon, P; Jan, S; Moisy, P

    2013-02-28

    In this study, speciation in aqueous solutions of nitric acid at 25 °C was assessed in two independent ways. First, Raman experiments were carried out and interpreted in terms of free nitrate ions, ion pairs and neutral HNO(3) molecules. In parallel, a model was developed to account for the formation of these two kinds of pairs. It was based on an extension of the binding mean spherical approximation (BiMSA), or associative MSA (AMSA), in which the size and the charge of the ions in the chemical pair may differ from those of the free ions. A simultaneous fit of the osmotic coefficient and of the proportion of free ions (obtained from Raman spectroscopy experiments) led to an estimation of the speciation in nitric acid solutions. The result obtained using this procedure was compared with the estimation obtained from the Raman experiments.

  3. Nylon Dissolution in Nitric Acid Solutions

    SciTech Connect

    KESSINGER, GLENF.

    2004-06-16

    H Area Operations is planning to process Pu-contaminated uranium scrap in support of de-inventory efforts. Nylon bags will be used to hold materials to be dissolved in H-Canyon. Based on this set of twelve nylon dissolutions, it is concluded that (when other variables are held constant): increased acid concentration results in increased dissolution rates; increased acid concentration results in a lower dissolution onset temperature; little, if any, H plus is consumed during the depolymerization process; and 2.0-3.0 M HNO3, with 0.025 M KF and 2 g/L B, is satisfactory for the dissolution of nylon bag materials to be used during H-Canyon processing.

  4. AMTEC vapor-vapor series connected cells

    NASA Technical Reports Server (NTRS)

    Underwood, Mark L. (Inventor); Williams, Roger M. (Inventor); Ryan, Margaret A. (Inventor); Nakamura, Barbara J. (Inventor); Oconnor, Dennis E. (Inventor)

    1995-01-01

    An alkali metal thermoelectric converter (AMTEC) having a plurality of cells structurally connected in series to form a septum dividing a plenum into two chambers, and electrically connected in series, is provided with porous metal anodes and porous metal cathodes in the cells. The cells may be planar or annular, and in either case a metal alkali vapor at a high temperature is provided to the plenum through one chamber on one side of the wall and returned to a vapor boiler after condensation at a chamber on the other side of the wall in the plenum. If the cells are annular, a heating core may be placed along the axis of the stacked cells. This arrangement of series-connected cells allows efficient generation of power at high voltage and low current.

  5. AMTEC vapor-vapor series connected cells

    NASA Astrophysics Data System (ADS)

    Underwood, Mark L.; Williams, Robert M.; Ryan, Margaret A.; Jeffries-Nakamura, Barbara; Oconnor, Dennis

    1993-01-01

    An alkali metal thermoelectric converter (AMTEC) having a plurality of cells structurally connected in series to form a septum dividing a plenum into two chambers, and electrically connected in series, is provided with porous metal anodes and porous metal cathodes in the cells. The cells may be planar or annular, and in either case a metal alkali vapor at a high temperature is provided to the plenum through one chamber on one side of the wall and returned to a vapor boiler after condensation at a chamber on the other side of the wall in the plenum. If the cells are annular, a heating core may be placed along the axis of the stacked cells. This arrangement of series-connected cells allows efficient generation of power at high voltage and low current.

  6. AMTEC vapor-vapor series connected cells

    NASA Astrophysics Data System (ADS)

    Underwood, Mark L.; Williams, Roger M.; Ryan, Margaret A.; Nakamura, Barbara J.; Oconnor, Dennis E.

    1995-08-01

    An alkali metal thermoelectric converter (AMTEC) having a plurality of cells structurally connected in series to form a septum dividing a plenum into two chambers, and electrically connected in series, is provided with porous metal anodes and porous metal cathodes in the cells. The cells may be planar or annular, and in either case a metal alkali vapor at a high temperature is provided to the plenum through one chamber on one side of the wall and returned to a vapor boiler after condensation at a chamber on the other side of the wall in the plenum. If the cells are annular, a heating core may be placed along the axis of the stacked cells. This arrangement of series-connected cells allows efficient generation of power at high voltage and low current.

  7. Nitric Acid Particles in Cold Thick Ice Clouds Observed at Global Scale: Link with Lightning, Temperature, and Upper Tropospheric Water Vapor

    NASA Technical Reports Server (NTRS)

    Chepfer, H.; Minnis, P.; Dubuisson, P.; Chiriaco, M.; Sun-Mack, S.; Riviere, E. D.

    2007-01-01

    Signatures of nitric acid particles (NAP) in cold thick ice clouds have been derived from satellite observations. Most NAP are detected in the Tropics (9 to 20% of clouds with T less than 202.5 K). Higher occurrences were found in the rare mid-latitudes very cold clouds. NAP occurrence increases as cloud temperature decreases and NAP are more numerous in January than July. Comparisons of NAP and lightning distributions show that lightning is the main source of the NOx, which forms NAP in cold clouds. Qualitative comparisons of NAP with upper tropospheric humidity distributions suggest that NAP play a role in the dehydration of the upper troposphere when the tropopause is colder than 195K.

  8. Second Vapor-Level Sensor For Vapor Degreaser

    NASA Technical Reports Server (NTRS)

    Painter, Nance M.; Burley, Richard K.

    1990-01-01

    Second vapor-level sensor installed at lower level in vapor degreaser makes possible to maintain top of vapor at that lower level. Evaporation reduced during idle periods. Provides substantial benefit, without major capital cost of building new vapor degreaser with greater freeboard height.

  9. Gasoline Vapor Recovery

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Gasoline is volatile and some of it evaporates during storage, giving off hydrocarbon vapor. Formerly, the vapor was vented into the atmosphere but anti-pollution regulations have precluded that practice in many localities, so oil companies and storage terminals are installing systems to recover hydrocarbon vapor. Recovery provides an energy conservation bonus in that most of the vapor can be reconverted to gasoline. Two such recovery systems are shown in the accompanying photographs (mid-photo at right and in the foreground below). They are actually two models of the same system, although.configured differently because they are customized to users' needs. They were developed and are being manufactured by Edwards Engineering Corporation, Pompton Plains, New Jersey. NASA technological information proved useful in development of the equipment.

  10. Vapor Control Layer Recommendations

    SciTech Connect

    2009-09-08

    This information sheet describes the level of vapor control required on the interior side of framed walls with typical fibrous cavity insulation (fibreglass, rockwool, or cellulose, based on DOE climate zone of construction.

  11. Study of the acidic deposition phenomenon over Alexandria city.

    PubMed

    Noweir, Kamal H; El-Marakby, Fadia A; Zaki, Gihan R; Ibrahim, Alaa K

    2008-01-01

    Acid deposition commonly occurs due to conversion of primary acidic pollutants (SO2 & NO2) into secondary pollutants (H2SO4 & HNO3 and their salts). The main natural sources of acid deposition in Alexandria include lightening and microbial processes. Anthropogenic sources include traffic, industrial, fuel burning, and incineration activities. Acid deposition has ecological and economic effects in addition to health effects. The objective of this study is to assess acidity of dry and wet depositions in the atmosphere of Alexandria. Dry samples were collected as settled dust using plastic jar. Wet samples were collected as rain water using polyethylene bottle. All samples were analyzed for pH, sulfates, and nitrates. The relatively high pH values observed in depositions of Alexandria city (6.95+/-0.22) and (7.14+/-0.49) for settled dust and rain water respectively indicating the conversion of the formed acids (H2SO4 & HNO3) into their salts. This explanation was confirmed by the relatively high concentrations of sulfates and nitrates. The average values were (14.3+/-4.21 g/km2/month and 20.5+/-9.5mg/L for sulfates), and (22.6+/-10.6 g/km2/month and 0.5+/-0.32 mg/L for nitrates) for settled dust and rainwater samples respectively. It can be concluded that Alexandria is a lucky city regarding acidity of the atmosphere due to its geographic, topographic, and meteorological features. Building up acid deposition monitoring network that covers all Egyptian cities to be a nucleus for African network, using new technologies that reduce emission of acid deposition precursors and alternative sources of energy, implementing and enforcing regulations and standards for major pollutants, and increasing public awareness are recommended.

  12. The interaction of propionic and butyric acids with ice and HNO₃-doped ice surfaces at 195-212 K.

    PubMed

    Romanias, Manolis N; Papadimitriou, Vassileios C; Papagiannakopoulos, Panos

    2014-12-01

    The interaction of propionic and butyric acids on ice and HNO3-doped ice were studied between 195 and 212 K and low concentrations, using a Knudsen flow reactor coupled with a quadrupole mass spectrometer. The initial uptake coefficients (γ0) of propionic and butyric acids on ice as a function of temperature are given by the expressions: γ0(T) = (7.30 ± 1.0) × 10(-10) exp[(3216 ± 478)/T] and γ0(T) = (6.36 ± 0.76) × 10(-11) exp[(3810 ± 434)/T], respectively; the quoted error limits are at 95% level of confidence. Similarly, γ0 of propionic acid on 1.96 wt % (A) and 7.69 wt % (B) HNO3-doped ice with temperature are given as γ(0,A)(T) = (2.89 ± 0.26) × 10(-8) exp[(2517 ± 266)/T] and γ(0,B)(T) = (2.77 ± 0.29) × 10(-7) exp[(2126 ± 206)/T], respectively. The results show that γ0 of C1 to C4 n-carboxylic acids on ice increase with the alkyl-group length, due to lateral interactions between alkyl-groups that favor a more perpendicular orientation and well packing of H-bonded monomers on ice. The high uptakes (>10(15) molecules cm(-2)) and long recovery signals indicate efficient growth of random multilayers above the first monolayer driven by significant van der Waals interactions. The heterogeneous loss of both acids on ice and HNO3-doped ice particles in dense cirrus clouds is estimated to take a few minutes, signifying rapid local heterogeneous removal by dense cirrus clouds.

  13. Electronic and optical characteristics of an m-plane GaN single crystal grown by hydride vapor phase epitaxy on a GaN seed synthesized by the ammonothermal method using an acidic mineralizer

    NASA Astrophysics Data System (ADS)

    Kojima, Kazunobu; Tsukada, Yusuke; Furukawa, Erika; Saito, Makoto; Mikawa, Yutaka; Kubo, Shuichi; Ikeda, Hirotaka; Fujito, Kenji; Uedono, Akira; Chichibu, Shigefusa F.

    2016-05-01

    Fundamental electronic and optical properties of a low-resistivity m-plane GaN single crystal, which was grown by hydride vapor phase epitaxy on a bulk GaN seed crystal synthesized by the ammonothermal method in supercritical ammonia using an acidic mineralizer, were investigated. The threading dislocation and basal-plane staking-fault densities of the crystal were around 104 cm-2 and less than 100 cm-1, respectively. Oxygen doping achieved a high electron concentration of 4 × 1018 cm-3 at room temperature. Accordingly, a photoluminescence (PL) band originating from the recombination of hot carriers was observed at low temperatures, even under weak excitation conditions. The simultaneous realization of low-level incorporation of Ga vacancies (VGa) less than 1016 cm-3 was confirmed by using the positron annihilation technique. Consistent with our long-standing claim that VGa complexes are the major nonradiative recombination centers in GaN, the fast-component PL lifetime of the near-band-edge emission at room temperature longer than 2 ns was achieved.

  14. Size-controlled synthesis and formation mechanism of manganese oxide OMS-2 nanowires under reflux conditions with KMnO4 and inorganic acids

    NASA Astrophysics Data System (ADS)

    Zhang, Qin; Cheng, Xiaodi; Qiu, Guohong; Liu, Fan; Feng, Xionghan

    2016-05-01

    This study presents a simplified approach for size-controlled synthesis of manganese oxide octahedral molecular sieve (OMS-2) nanowires using potassium permanganate (KMnO4) and different inorganic acids (HCl, HNO3, and H2SO4) under reflux conditions. The morphology and nanostructure of the synthesized products are characterized by X-ray diffraction, Ar adsorption, and electron microscopy analysis, in order to elucidate the controlling effects of acid concentration and type as well as the formation mechanism of OMS-2 nanowires. The concentration of inorganic acid is a crucial factor controlling the phase of the synthesized products. OMS-2 nanowires are obtained with HCl at the concentration ≥0.96 mol/L or with HNO3 and H2SO4 at the concentrations ≥0.72 mol/L. Differently, the type of inorganic acid effectively determines the particle size of OMS-2 nanowires. When the acid is changed from HCl to HNO3 and H2SO4 in the reflux system, the average length of OMS-2 declines significantly by 60-70% (1104-442 and 339 nm), with minor decreased in the average width (43-39 and 34 nm). The formation of OMS-2 nanowires under reflux conditions with KMnO4 and inorganic acids involves a two-step process, i.e., the initial formation of layered manganese oxides, and subsequent transformation to OMS-2 via a dissolution-recrystallization process under acidic conditions. The proposed reflux route provides an alternative approach for synthesizing OMS-2 nanowires as well as other porous nano-crystalline OMS materials.

  15. Size-controlled synthesis and formation mechanism of manganese oxide OMS-2 nanowires under reflux conditions with KMnO4 and inorganic acids

    NASA Astrophysics Data System (ADS)

    Zhang, Qin; Cheng, Xiaodi; Qiu, Guohong; Liu, Fan; Feng, Xionghan

    2016-05-01

    This study presents a simplified approach for size-controlled synthesis of manganese oxide octahedral molecular sieve (OMS-2) nanowires using potassium permanganate (KMnO4) and different inorganic acids (HCl, HNO3, and H2SO4) under reflux conditions. The morphology and nanostructure of the synthesized products are characterized by X-ray diffraction, Ar adsorption, and electron microscopy analysis, in order to elucidate the controlling effects of acid concentration and type as well as the formation mechanism of OMS-2 nanowires. The concentration of inorganic acid is a crucial factor controlling the phase of the synthesized products. OMS-2 nanowires are obtained with HCl at the concentration ≥0.96 mol/L or with HNO3 and H2SO4 at the concentrations ≥0.72 mol/L. Differently, the type of inorganic acid effectively determines the particle size of OMS-2 nanowires. When the acid is changed from HCl to HNO3 and H2SO4 in the reflux system, the average length of OMS-2 declines significantly by 60-70% (1104-442 and 339 nm), with minor decreased in the average width (43-39 and 34 nm). The formation of OMS-2 nanowires under reflux conditions with KMnO4 and inorganic acids involves a two-step process, i.e., the initial formation of layered manganese oxides, and subsequent transformation to OMS-2 via a dissolution-recrystallization process under acidic conditions. The proposed reflux route provides an alternative approach for synthesizing OMS-2 nanowires as well as other porous nano-crystalline OMS materials.

  16. Sporicidal Activity of the KMT reagent in its vapor phase against Geobacillus stearothermophilus Spores.

    PubMed

    Kida, Nori; Mochizuki, Yasushi; Taguchi, Fumiaki

    2007-01-01

    In an investigation of the sporicidal activity of the KMT reagent, a vapor phase study was performed using five kinds of carriers contaminated with Geobacillus stearothermophilus spores. When 25 ml of the KMT reagent was vaporized in a chamber (capacity; approximately 95 liters), the 2-step heating method (vaporization by a combination of low temperature and high temperature) showed the most effective sporicidal activity in comparison with the 1-step heating method (rapid vaporization). The 2-step heating method appeared to be related to the sporicidal activity of vaporized KMT reagent, i.e., ethanol and iodine, which vaporized mainly when heated at a low temperature such as 55 C, and acidic water, which vaporized mainly when heated at a high temperature such as 300 C. We proposed that the KMT reagent can be used as a new disinfectant not only in the liquid phase but also in the vapor phase in the same way as peracetic acid and hydrogen peroxide. PMID:17237604

  17. Formation of substrate-based gold nanocage chains through dealloying with nitric acid

    PubMed Central

    Yan, Ziren; Wu, Ying

    2015-01-01

    Summary Metal nanocages have raised great interest because of their new properties and wide applications. Here, we report on the use of galvanic replacement reactions to synthesize substrate-supported Ag–Au nanocages from silver templates electrodeposited on transparent indium tin oxide (ITO) film coated glass. The residual Ag in the composition was dealloyed with 10% nitric acid. It was found that chains of Au nanocages were formed on the substrate surface during dealloying. When the concentration of HNO3 increased to 20%, the structures of nanocages were damaged and formed crescent or semi-circular shapes. The transfer process on the substrate surface was discussed. PMID:26199839

  18. A study of Type I polar stratospheric cloud formation

    NASA Technical Reports Server (NTRS)

    Tabazadeh, A.; Turco, R. P.; Drdla, K.; Jacobson, M. Z.; Toon, O. B.

    1994-01-01

    Mechanisms for the formation of Type I (nitric acid-based) polar stratospheric clouds (PSCs) are discussed. If the pre-existing sulfate aerosols are liquid prior to PSC formation, then nitric acid particles (Type Ib) form by HNO3 dissolution in aqueous H2SO4 solution droplets. This process does not require a nucleation step for the formation of HNO3 aerosols, so most pre-existing aerosols grow to become relatively small HNO3-containing particles. At significantly lower temperatures, the resulting supercooled solutions (Type Ib) may freeze to form HNO3 ice particles (Type Ia). If the pre-existing sulfate aerosols are initially solid before PSC formation, then HNO3 vapor can be deposited directly on the frozen sulfate particles. However, because an energy barrier to the condensation exists a nucleation mechanism is involved. Here, we suggest a unique nucleation mechanism that involves formation of HNO3/H20 solutions on the sulfate ice particles. These nucleation processes may be highly selective, resulting in the formation of relatively small number of large particles.

  19. Determination of mercury in gasoline by cold vapor atomic absorption spectrometry with direct reduction in microemulsion media

    NASA Astrophysics Data System (ADS)

    Brandão, Geisamanda Pedrini; de Campos, Reinaldo Calixto; Luna, Aderval Severino

    2005-06-01

    The determination of Hg in gasoline by cold vapor atomic absorption spectrometry, after direct aqueous NaBH 4 reduction in a three-component (microemulsion) medium, was investigated. Microemulsions were prepared by mixing gasoline with propan-1-ol and 50% v / v HNO 3 at a 20 : 15 : 1 volume ratio. A long-term homogeneous system was immediately formed this way. After reduction, the Hg vapor generated in a reaction flask was transported to an intermediate K 2Cr 2O 7/H 2SO 4 trap solution in order to avoid poisoning of the Au-Pt trap by the gasoline vapors. A second reduction step was then conducted and the generated Hg vapor transported to the Au-Pt trap, followed by thermal release of Hg 0 and atomic absorption measurement. Purified N 2 was used as purge and transport gas. After multivariate optimization by central composite design calibration graphs showed coefficients of correlation of 0.9999 and a characteristic mass of 2 ng was obtained. Typical coefficients of variation of 5% and 6% were found for ten consecutive measurements at concentration levels of 1 and 8 μg L -1 of Hg 2+, respectively. The limit of detection was 0.10 μg L -1 (0.14 μg kg -1) in the original sample. A total measurement cycle took 11 min, permitting duplicate analysis of 3 samples per hour. The results obtained with the proposed procedure in the analysis of commercial gasoline samples were in agreement with those obtained by a comparative procedure. Gasoline samples of the Rio de Janeiro city have shown Hg concentrations below 0.27 μg L -1.

  20. Speciation analysis of mercury in cereals by liquid chromatography chemical vapor generation inductively coupled plasma-mass spectrometry.

    PubMed

    Lin, Liang-Yen; Chang, Lan-Fang; Jiang, Shiuh-Jen

    2008-08-27

    A simple and rapid procedure for the separation and determination of inorganic, methyl, and ethyl mercury compounds was described using liquid chromatography (LC) followed by vapor generation inductively coupled plasma-mass spectrometry (VG-ICP-MS). Well resolved chromatograms were obtained within 5 min by reversed-phase liquid chromatography with a C8 column as the stationary phase and a pH 4.7 solution containing 0.5% v/v 2-mercaptoethanol and 5% v/v methanol as the mobile phase. The separated mercury compounds were converted to mercury vapors by an in situ nebulizer/vapor generation system for their introduction into ICP. The concentrations of NaBH4 and HNO3 required for vapor generation were also optimized. The method was applied for the speciation of mercury in reference materials NIST SRM 1568a Rice Flour and NIST SRM 1567a Wheat Flour and also rice flour and wheat flour samples purchased locally. The accuracy of the procedure was verified by analyzing the certified reference material NRCC DOLT-3 Dogfish Liver for methyl mercury. Precision between sample replicates was better than 13% for all the determinations. The detection limits of the mercury compounds studied were in the range 0.003-0.006 ng Hg mL(-1) in the injected solutions, which correspond to 0.02-0.06 ng g(-1) in original flour samples. A microwave-assisted extraction procedure was adopted for the extraction of mercury compounds from rice flour, wheat flour, and fish samples using a mobile phase solution.

  1. Large-Scale Distributions of Tropospheric Nitric, Formic, and Acetic acids Over the Westerm Pacific Basin During Wintertime

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Dibb, J. E.; Lefer, B. L.; Scheuer, E. M.; Bradshaw, J. D.; Sandholm, S. T.; Smyth, S.; Blake, D. R.; Blake, N. J.; Sachse, G. W.; Collins, J. E.; Gregory, G. L.

    1997-01-01

    We report here measurements of the acidic gases nitric (HNO3), formic (HCOOH), and acetic (CH3COOH) over the western Pacific basin during the February-March 1994 Pacific Exploratory Mission-West (PEM-West B). These data were obtained aboard the NASA DC-8 research aircraft as it flew missions in the altitude range of 0.3 - 12.5 km over equatorial regions near Guam and then further westward encompassing the entire Pacific Rim arc. Aged marine air over the equatorial Pacific generally exhibited mixing ratios of acidic gases less than 100 parts per trillion by volume (pptv). Near the Asian continent, discrete plumes encountered below 6 km altitude contained up to 8 parts per billion by volume (ppbv) HNO3 and 10 ppbv HCOOH and CH3COOH. Overall there was a general correlation between mixing ratios of acidic gases with those of CO, C2H2, and C2Cl4, indicative of emissions from combustion and industrial sources. The latitudinal distributions of HNO3 and CO showed that the largest mixing ratios were centered around 15 deg N, while HCOOH, CH3COOH, and C2Cl4 peaked at 25 deg N. The mixing ratios of HCOOH and CH3COOH were highly correlated (r(sup 2) = 0.87) below 6 km altitude, with a slope (0.89) characteristic of the nongrowing season at midlatitudes in the northern hemisphere. Above 6 km altitude, HCOOH and CH3COOH were marginally correlated (r(sup 2) = 0.50), and plumes well defined by CO, C2H2, and C2Cl4 were depleted in acidic gases, most likely due to scavenging during vertical transport of air masses through convective cloud systems over the Asian continent. In stratospheric air masses, HNO, mixing ratios were several parts per billion by volume (ppbv), yielding relationships with 03 and N2O consistent with those previously reported for NO(y).

  2. ExoMol molecular line lists - XI. The spectrum of nitric acid

    NASA Astrophysics Data System (ADS)

    Pavlyuchko, A. I.; Yurchenko, S. N.; Tennyson, Jonathan

    2015-09-01

    Nitric acid is a possible biomarker in the atmospheres of exoplanets. An accurate line list of rotational and rotational-vibrational transitions is computed for nitric acid (HNO3). This line list covers wavelengths longer than 1.42 μm (0-7000 cm-1) and temperatures up to 500 K. The line list is computed using a hybrid variational - perturbation theory and empirically tuned potential energy and dipole surfaces. It comprises almost seven billion transitions involving rotations up to J = 100. Comparisons with spectra from the HITRAN and Pacific Northwest National Laboratory data bases demonstrate the accuracy of our calculations. Synthetic spectra of water-nitric acid mixtures suggest that nitric acid has features at 7.5 and 11.25 μm that are capable of providing a clear signature for HNO3; the feature at 11.25 μm is particularly promising. Partition functions plus full line lists of transitions are made available in an electronic form as supplementary data to the article and at www.exomol.com.

  3. Venus Balloons using Water Vapor

    NASA Astrophysics Data System (ADS)

    Izutsu, N.; Yajima, N.; Honda, H.; Imamura, T.

    We propose an inflatable balloon using water vapor for the lifting gas, which is liquid in the transportation stage before entry into the high temperature atmosphere. The envelope of the balloon has an outer layer for gas barrier (a high-temperature resistant film) and an inner layer for liquid water keeping. In the descent stage using a parachute, water widely held just inside the balloon envelope can be quickly vaporized by a lot of heat flux from the surrounding high-temperature atmosphere owing to the large surface area of the balloon. As neither gas containers nor heat exchangers are necessary, we can construct a simple, lightweight and small size Venus balloon probe system. Tentative floating altitude is 35 km below the thick clouds in the Venusian atmosphere. Selection of balloon shape and material for balloon envelope are discussed in consideration of the Venusian environment such as high-temperature, high-pressure, and sulfuric acid. Balloon deployment and inflation sequence is numerically simulated. In case of the total floating mass of 10 kg at the altitude of 35 km, the volume and mass of the balloon is 1.5 cubic meters, and 3.5 kg, respectively. The shape of the balloon is chosen to be cylindrical with a small diameter. The mass of li fting gas can be determined as 4.3 kg and the remaining 2.2 kg becomes the payload mass. The mass of the total balloon system is also just 10 kg excluding the entry capsule.

  4. Vapor core propulsion reactors

    NASA Technical Reports Server (NTRS)

    Diaz, Nils J.

    1991-01-01

    Many research issues were addressed. For example, it became obvious that uranium tetrafluoride (UF4) is a most preferred fuel over uranium hexafluoride (UF6). UF4 has a very attractive vaporization point (1 atm at 1800 K). Materials compatible with UF4 were looked at, like tungsten, molybdenum, rhenium, carbon. It was found that in the molten state, UF4 and uranium attacked most everything, but in the vapor state they are not that bad. Compatible materials were identified for both the liquid and vapor states. A series of analyses were established to determine how the cavity should be designed. A series of experiments were performed to determine the properties of the fluid, including enhancement of the electrical conductivity of the system. CFD's and experimental programs are available that deal with most of the major issues.

  5. Fuel Vaporization Effects

    NASA Technical Reports Server (NTRS)

    Bosque, M. A.

    1983-01-01

    A study of the effects of fuel-air preparation characteristics on combustor performance and emissions at temperature and pressure ranges representative of actual gas turbine combustors is discussed. The effect of flameholding devices on the vaporization process and NOx formation is discussed. Flameholder blockage and geometry are some of the elements that affect the recirculation zone characteristics and subsequently alter combustion stability, emissions and performance. A water cooled combustor is used as the test rig. Preheated air and Jet A fuel are mixed at the entrance of the apparatus. A vaporization probe is used to determine percentage of vaporization and a gas sample probe to determine concentration of emissions in the exhaust gases. The experimental design is presented and experimental expected results are discussed.

  6. Infrared spectrum of nitric acid dihydrate: Influence of particle shape.

    PubMed

    Wagner, Robert; Möhler, Ottmar; Saathoff, Harald; Stetzer, Olaf; Schurath, Ulrich

    2005-03-24

    In situ Fourier transform infrared (FTIR) extinction spectra of airborne alpha-NAD microparticles generated by two different methods were recorded in the large coolable aerosol chamber AIDA of Forschungszentrum Karlsruhe. The extinction spectrum of alpha-NAD crystals obtained by shock freezing of a HNO3/H2O gas mixture could be accurately reproduced using Mie theory with published refractive indices of alpha-NAD as input. In contrast, Mie theory proved to be inadequate to properly reproduce the infrared extinction spectrum of alpha-NAD crystals which were formed via homogeneous nucleation of supercooled HNO3/H2O solution droplets, evaporating slowly on a time scale of several hours at about 195 K. Much better agreement between measured and calculated extinction spectra was obtained by T-matrix calculations assuming oblate particles with aspect ratios greater than five. This indicates that strongly aspherical alpha-NAD crystals are obtained when supercooled nitric acid solution droplets freeze and grow slowly, a process which has been discussed as a potential pathway to the formation of crystalline polar stratospheric cloud (PSC) particles. PMID:16833561

  7. Vapor concentration monitor

    DOEpatents

    Bayly, John G.; Booth, Ronald J.

    1977-01-01

    An apparatus for monitoring the concentration of a vapor, such as heavy water, having at least one narrow bandwidth in its absorption spectrum, in a sample gas such as air. The air is drawn into a chamber in which the vapor content is measured by means of its radiation absorption spectrum. High sensitivity is obtained by modulating the wavelength at a relatively high frequency without changing its optical path, while high stability against zero drift is obtained by the low frequency interchange of the sample gas to be monitored and of a reference sample. The variable HDO background due to natural humidity is automatically corrected.

  8. Effect of Acid Oxidation on the Dispersion Property of Multiwalled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Goh, P. S.; Ismail, A. F.; Aziz, M.

    2009-06-01

    A means of dispersion of multiwalled carbon nanotube (MWCNT) via mixed acid (HNO3 and H2SO4) oxidation with different treatment durations was investigated through the solubility study of the treated carbon nanotubes in some common solvents. Fourier transformed infrared (FTIR) characterization of the reaction products revealed that the surface of MWCNTs was successfully functionalized with surface acidic groups. The acid-base titration demonstrated that the amount of surface acidic groups increased in parallel with the refluxing duration. The acid modified MWCNTs were found to be well dispersed in polar solvents, such as ethanol and water due to the presence of the hydrophilic acid functional groups on the surface of raw MWCNTs. Such chemical modification of carbon nanotube properties will pave the way towards the realistic applications in the nanotechnology world.

  9. BTSC VAPOR INSTRUSION PRIMER "VAPOR INTRUSION CONSIDERATION FOR REDEVELOPMENT"

    EPA Science Inventory

    This primer is designed for brownfields stakeholders concerned about vapor intrusion, including property owners, real estate developers, and contractors performing environmental site investigations. It provides an overview of the vapor intrusion issue and how it can impact the ap...

  10. Water vapor lidar

    NASA Technical Reports Server (NTRS)

    Ellingson, R.; Mcilrath, T.; Schwemmer, G.; Wilkerson, T. D.

    1976-01-01

    The feasibility was studied of measuring atmospheric water vapor by means of a tunable lidar operated from the space shuttle. The specific method evaluated was differential absorption, a two-color method in which the atmospheric path of interest is traversed by two laser pulses. Results are reported.

  11. Passive Vaporizing Heat Sink

    NASA Technical Reports Server (NTRS)

    Knowles, TImothy R.; Ashford, Victor A.; Carpenter, Michael G.; Bier, Thomas M.

    2011-01-01

    A passive vaporizing heat sink has been developed as a relatively lightweight, compact alternative to related prior heat sinks based, variously, on evaporation of sprayed liquids or on sublimation of solids. This heat sink is designed for short-term dissipation of a large amount of heat and was originally intended for use in regulating the temperature of spacecraft equipment during launch or re-entry. It could also be useful in a terrestrial setting in which there is a requirement for a lightweight, compact means of short-term cooling. This heat sink includes a hermetic package closed with a pressure-relief valve and containing an expendable and rechargeable coolant liquid (e.g., water) and a conductive carbon-fiber wick. The vapor of the liquid escapes when the temperature exceeds the boiling point corresponding to the vapor pressure determined by the setting of the pressure-relief valve. The great advantage of this heat sink over a melting-paraffin or similar phase-change heat sink of equal capacity is that by virtue of the =10x greater latent heat of vaporization, a coolant-liquid volume equal to =1/10 of the paraffin volume can suffice.

  12. Solvent vapor collector

    DOEpatents

    Ellison, Kenneth; Whike, Alan S.

    1979-01-30

    A solvent vapor collector is mounted on the upstream inlet end of an oven having a gas-circulating means and intended for curing a coating applied to a strip sheet metal at a coating station. The strip sheet metal may be hot and solvent vapors are evaporated at the coating station and from the strip as it passes from the coating station to the oven. Upper and lower plenums within a housing of the collector are supplied with oven gases or air from the gas-circulating means and such gases or air are discharged within the collector obliquely in a downstream direction against the strip passing through that collector to establish downstream gas flows along the top and under surfaces of the strip so as, in turn, to induct solvent vapors into the collector at the coating station. A telescopic multi-piece shroud is usefully provided on the housing for movement between an extended position in which it overlies the coating station to collect solvent vapors released thereat and a retracted position permitting ready cleaning and adjustment of that coating station.

  13. Water vapor diffusion membranes

    NASA Technical Reports Server (NTRS)

    Holland, F. F., Jr.; Smith, J. K.

    1974-01-01

    The program is reported, which was designed to define the membrane technology of the vapor diffusion water recovery process and to test this technology using commercially available or experimental membranes. One membrane was selected, on the basis of the defined technology, and was subjected to a 30-day demonstration trial.

  14. Enthalpy of Vaporization and Vapor Pressures: An Inexpensive Apparatus

    ERIC Educational Resources Information Center

    Battino, Rubin; Dolson, David A.; Hall, Michael A.; Letcher, Trevor M.

    2007-01-01

    A simple and inexpensive method to determine the enthalpy of vaporization of liquids by measuring vapor pressure as a function of temperature is described. The vapor pressures measured with the stopcock cell were higher than the literature values and those measured with the sidearm rubber septum cell were both higher and lower than literature…

  15. Thermogravimetric study of vapor pressure of TATP synthesized without recrystallization.

    PubMed

    Mbah, Jonathan; Knott, Debra; Steward, Scott

    2014-11-01

    This study aims at characterizing the vapor pressure signatures generated by triacetone triperoxide (TATP) that was synthesized without recrystallization by thermogravimmetric analysis (TGA) for exploitation by standoff detection technologies of explosive devices. The thermal behavior of the nonrecrystallized sample was compared with reported values. Any phase change, melting point and decomposition identification were studied by differential scanning calorimeter. Vapor pressures were estimated by the Langmuir method of evaporation from an open surface in a vacuum. Vapor pressures of TATP at different temperatures were calculated using the linear logarithmic relationship obtained from benzoic acid reference standard. Sublimation of TATP was found to follow apparent zero-order kinetics and sublimes at steady rates at 298 K and above. While the enthalpy of sublimation found, 71.7 kJ mol(-1), is in agreement with reported values the vapor pressures deviated significantly. The differences in the vapor pressures behavior are attributable to the synthesis pathway chosen in this study. PMID:25127637

  16. Thermogravimetric study of vapor pressure of TATP synthesized without recrystallization.

    PubMed

    Mbah, Jonathan; Knott, Debra; Steward, Scott

    2014-11-01

    This study aims at characterizing the vapor pressure signatures generated by triacetone triperoxide (TATP) that was synthesized without recrystallization by thermogravimmetric analysis (TGA) for exploitation by standoff detection technologies of explosive devices. The thermal behavior of the nonrecrystallized sample was compared with reported values. Any phase change, melting point and decomposition identification were studied by differential scanning calorimeter. Vapor pressures were estimated by the Langmuir method of evaporation from an open surface in a vacuum. Vapor pressures of TATP at different temperatures were calculated using the linear logarithmic relationship obtained from benzoic acid reference standard. Sublimation of TATP was found to follow apparent zero-order kinetics and sublimes at steady rates at 298 K and above. While the enthalpy of sublimation found, 71.7 kJ mol(-1), is in agreement with reported values the vapor pressures deviated significantly. The differences in the vapor pressures behavior are attributable to the synthesis pathway chosen in this study.

  17. Acidity decline in Antarctic ice cores during the Little Ice Age linked to changes in atmospheric nitrate and sea salt concentrations

    NASA Astrophysics Data System (ADS)

    Pasteris, Daniel; McConnell, Joseph R.; Edwards, Ross; Isaksson, Elizabeth; Albert, Mary R.

    2014-05-01

    Acidity is an important chemical variable that impacts atmospheric and snowpack chemistry. Here we describe composite time series and the spatial pattern of acidity concentration (Acy = H+ - HCO3-) during the last 2000 years across the Dronning Maud Land region of the East Antarctic Plateau using measurements in seven ice cores. Coregistered measurements of the major ion species show that sulfuric acid (H2SO4), nitric acid (HNO3), and hydrochloric acid (HCl) determine greater than 98% of the acidity value. The latter, also described as excess chloride (ExCl-), is shown mostly to be derived from postdepositional diffusion of chloride with little net gain or loss from the snowpack. A strong inverse linear relationship between nitrate concentration and inverse accumulation rate provides evidence of spatially homogenous fresh snow concentrations and reemission rates of nitrate from the snowpack across the study area. A decline in acidity during the Little Ice Age (LIA, 1500-1900 Common Era) is observed and is linked to declines in HNO3 and ExCl- during that time. The nitrate decline is found to correlate well with published methane isotope data from Antarctica (δ13CH4), indicating that it is caused by a decline in biomass burning. The decrease in ExCl- concentration during the LIA is well correlated to published sea surface temperature reconstructions in the Atlantic Ocean, which suggests increased sea salt aerosol production associated with greater sea ice extent.

  18. Electrical resistance response of polyaniline films to water, ethanol, and nitric acid solution

    NASA Astrophysics Data System (ADS)

    Yin, Hong-Xing; Li, Meng-Meng; Yang, H.; Long, Yun-Ze; Sun, Xin

    2010-08-01

    This paper reports on electrical resistance vs. aging time for the response of polyaniline films under exposure to water, ethanol and nitric acid (HNO3) solution. Camphor sulfonic acid-doped polyaniline films were prepared by a “doping-dedoping-redoping" method, the morphology and microstructures of the films were characterized by a scanning electron microscope and an x-ray diffractometer, the electrical resistance was measured by a four-probe method. It was found that a lower amount of water molecules infiltrating the film can decrease the film's resistance possibly due to an enhancement of charge carrier transfer between polyaniline chains, whereas excessive water molecules can swell inter-chain distances and result in a quick increase of resistance. The resistance of the film under exposure to ethanol increases and becomes much larger than the original value. However, HNO3 solution can decrease the film's resistance sharply possibly owing to doping effect of protonic acid. These results can help to understand the conduction mechanism in polyaniline films, and also indicate that the films have potential application in chemical sensors.

  19. Localized corrosion effects and modifications of acidic and alkaline slurries on copper chemical mechanical polishing

    NASA Astrophysics Data System (ADS)

    Tsai, Tzu-Hsuan; Yen, Shi-Chern

    2003-04-01

    This study demonstrates the CMP performance can be enhanced by modifying the corrosion effects of acidic and alkaline slurries on copper. A corrosion test-cell with a polishing platform is connected with the potentiostat to investigate the corrosion behaviors of copper CMP in various alumina slurries. Experiments show that the slurry needs to be maintained in acidic pH<4.56 or alkaline pH>9.05 surroundings and thus better dispersion of alumina particles and less residual contaminant on copper surface can be obtained. The surface defects after copper CMP using acidic and alkaline slurries are described by pitting corrosion mechanisms, and these mechanisms can be regarded as a basis to modify their corrosion effects. Experimental results indicate that it is necessary to modify the dissolution of HNO 3 and oxidization of NH 4OH for copper CMP slurries. Consequently, the slurries of 5 wt.% HNO 3 by adding 0.1 wt.% BTA or 5 wt.% KNO 3 by adding 1 wt.% NH 4OH achieve good CMP performance for copper with higher CMP efficiency factor (CMPEF), 1460 and 486, and lower surface roughness ( Rq), 4.019 and 3.971 nm, respectively. It is found that AFM micrographs can support the effectiveness of corrosion modifications for copper CMP in various slurry chemistries.

  20. The formic acid-nitric acid complex: microwave spectrum, structure, and proton transfer.

    PubMed

    Mackenzie, Rebecca B; Dewberry, Christopher T; Leopold, Kenneth R

    2014-09-11

    Rotational spectra are reported for seven isotopologues of the complex HCOOH-HNO3 in a supersonic jet. The system is planar and bound by a pair of hydrogen bonds, much like the more widely studied carboxylic acid dimers. Double proton exchange interconverts the system between a pair of equivalent structures, as revealed by a splitting of the a-type spectrum that disappears when one of the hydrogen bonding protons is replaced by deuterium. The observation of relative intensities that are consistent with nuclear spin statistics in a symmetric and antisymmetric pair of tunneling states provides additional evidence for such a motion. The observed splittings in the pure rotational spectrum are 1-2 orders of magnitude smaller than those recently reported in the pure rotational spectra of several related carboxylic acid dimers. This is a curious difference, although we note that because the observed spectra do not cross the tunneling doublet, the splittings are a measure of the difference in effective rotational constants for the two states, not the tunneling frequency itself. The observed rotational constants have been used to determine an accurate vibrationally averaged structure for the complex. The two hydrogen bond lengths, 1.686(17) Å and 1.813(10) Å for the hydrogen bonds involving the HNO3 and HCOOH protons, respectively, differ by 0.127(27) Å. Likewise, the associated oxygen-oxygen distances determined for the parent species, 2.631 and 2.794 Å, differ by 0.163 Å. These results suggest that the double proton transfer is necessarily accompanied by substantial motion of the heavy atom frame, and thus this system, in principle, provides an excellent prototype for multidimensional tunneling processes. Ab initio calculations of the binding energy and the barrier height are presented. Excellent agreement between the calculated equilibrium structure and the experimental, vibrationally averaged structure suggests that the vibrational wave function is not highly

  1. Ambient concentrations of atmospheric ammonia, nitrogen dioxide and nitric acid in an intensive agricultural region

    NASA Astrophysics Data System (ADS)

    Zbieranowski, Antoni L.; Aherne, Julian

    2013-05-01

    The spatial and temporal distribution of ambient atmospheric gaseous reactive nitrogen (Nr) species concentrations (ammonia [NH3], nitrogen dioxide [NO2] and nitric acid [HNO3]) were measured at the field scale in an intensive agricultural region in southern Ontario, Canada. Atmospheric concentrations were measured with the Willems badge diffusive passive sampler (18 sites for NH3, 9 sites for NO2 and HNO3) for one year (April 2010-March 2011; under a two week measurement frequency) within a 15 km × 15 km area. Dry deposition was calculated using the inferential method and estimated across the entire study area. The spatial distribution of emission sources associated with agricultural activity resulted in high spatial variability in annual average ambient NH3 concentrations (<3->8 μg m-3 within a 2 km distance, coefficient of variation ˜50%) and estimated dry deposition (4-13 kg N ha-1 yr-1) between sample sites. In contrast, ambient concentrations and deposition of both NO2 (˜5.2->6.5 μg m-3; 1.0-1.5 kg N ha-1 yr-1) and HNO3 (0.6-0.7 μg m-3; 0.5-1 kg N ha-1 yr-1) had low variability (coefficient of variation <10%). The observed NH3 concentrations accounted for ˜70% of gaseous Nr dry deposition. High NH3 concentrations suggest that reduced nitrogen species (NHx) will continue to make up an increasing fraction of Nr deposition within intensive agricultural regions in southern Ontario under legislated nitrogen oxide emission reductions. Further, estimated total inorganic Nr deposition (15-28 kg N ha-1 yr-1) may lead to potential changes in soil processes, nutrient imbalance and altered composition of mycorrhiza and ground vegetation within adjacent semi-natural ecosystems (estimated at ˜10% of the study area).

  2. Carbonic acid: an important intermediate in the surface chemistry of calcium carbonate.

    PubMed

    Al-Hosney, Hashim A; Grassian, Vicki H

    2004-07-01

    Calcium carbonate is an important and ubiquitous component of biological and geochemical systems. In this study, the surface chemistry of calcium carbonate with several trace atmospheric gases including HNO3, SO2, HCOOH, and CH3COOH is investigated with infrared spectroscopy. Adsorbed carbonic acid, H2CO3, is found to be an intermediate in these reactions. In the absence of adsorbed water, carbonic acid is stable on the surface at room temperature. However, upon water adsorption, carbonic acid dissociates as indicated by the evolution of gaseous CO2 and the disappearance of infrared absorption bands associated with adsorbed carbonic acid. Thus, it is postulated that under ambient conditions, carbonic acid may be an important albeit short-lived intermediate in the surface chemistry of calcium carbonate. PMID:15225019

  3. Proton transfer reactions between nitric acid and acetone, hydroxyacetone, acetaldehyde and benzaldehyde in the solid phase.

    PubMed

    Lasne, Jérôme; Laffon, Carine; Parent, Philippe

    2012-12-01

    The heterogeneous and homogeneous reactions of acetone, hydroxyacetone, acetaldehyde and benzaldehyde with solid nitric acid (HNO(3)) films have been studied with Reflection-Absorption Infrared Spectroscopy (RAIRS) under Ultra-High Vacuum (UHV) conditions in the 90-170 K temperature range. In the bulk or at the surface of the films, nitric acid transfers its proton to the carbonyl function of the organic molecules, producing protonated acetone-H(+), hydroxyacetone-H(+), acetaldehyde-H(+) and benzaldehyde-H(+), and nitrate anions NO(3)(-), a reaction not observed when nitric acid is previously hydrated [J. Lasne, C. Laffon and Ph. Parent, Phys. Chem. Chem. Phys., 2012, 14, 697]. This provides a molecular-scale description of the carbonyl protonation reaction in an acid medium, the first step of the acid-catalyzed condensation of carbonyl compounds, fuelling the growth of secondary organic aerosols (SOA) in the atmosphere.

  4. Chemical vapor deposition growth

    NASA Technical Reports Server (NTRS)

    Ruth, R. P.; Manasevit, H. M.; Kenty, J. L.; Moudy, L. A.; Simpson, W. I.; Yang, J. J.

    1976-01-01

    A chemical vapor deposition (CVD) reactor system with a vertical deposition chamber was used for the growth of Si films on glass, glass-ceramic, and polycrystalline ceramic substrates. Silicon vapor was produced by pyrolysis of SiH4 in a H2 or He carrier gas. Preliminary deposition experiments with two of the available glasses were not encouraging. Moderately encouraging results, however, were obtained with fired polycrystalline alumina substrates, which were used for Si deposition at temperatures above 1,000 C. The surfaces of both the substrates and the films were characterized by X-ray diffraction, reflection electron diffraction, scanning electron microscopy optical microscopy, and surface profilometric techniques. Several experiments were conducted to establish baseline performance data for the reactor system, including temperature distributions on the sample pedestal, effects of carrier gas flow rate on temperature and film thickness, and Si film growth rate as a function of temperature.

  5. Filter vapor trap

    DOEpatents

    Guon, Jerold

    1976-04-13

    A sintered filter trap is adapted for insertion in a gas stream of sodium vapor to condense and deposit sodium thereon. The filter is heated and operated above the melting temperature of sodium, resulting in a more efficient means to remove sodium particulates from the effluent inert gas emanating from the surface of a liquid sodium pool. Preferably the filter leaves are precoated with a natrophobic coating such as tetracosane.

  6. Water vaporization on Ceres

    NASA Technical Reports Server (NTRS)

    A'Hearn, Michael F.; Feldman, Paul D.

    1992-01-01

    A search is presently conducted for OH generated by the photodissociation of atmospheric water vapor in long-exposure IUE spectra of the region around Ceres. A statistically significant detection of OH is noted in an exposure off the northern limb of Ceres after perihelion. The amount of OH is consistent with a polar cap that might be replenished during winter by subsurface percolation, but which dissipates in summer.

  7. The vapor pressures of explosives

    SciTech Connect

    Ewing, Robert G.; Waltman, Melanie J.; Atkinson, David A.; Grate, Jay W.; Hotchkiss, Peter

    2013-01-05

    The vapor pressures of many explosive compounds are extremely low and thus determining accurate values proves difficult. Many researchers, using a variety of methods, have measured and reported the vapor pressures of explosives compounds at single temperatures, or as a function of temperature using vapor pressure equations. There are large variations in reported vapor pressures for many of these compounds, and some errors exist within individual papers. This article provides a review of explosive vapor pressures and describes the methods used to determine them. We have compiled primary vapor pressure relationships traceable to the original citations and include the temperature ranges for which they have been determined. Corrected values are reported as needed and described in the text. In addition, after critically examining the available data, we calculate and tabulate vapor pressures at 25 °C.

  8. Determination of mercury in biological samples by cold vapor atomic absorption spectrometry following cloud point extraction with salt-induced phase separation.

    PubMed

    Dittert, Ingrid M; Maranhão, Tatiane A; Borges, Daniel L G; Vieira, Mariana A; Welz, Bernhard; Curtius, Adilson J

    2007-07-31

    Method development for the pre-concentration of mercury in human hair, dogfish liver and dogfish muscle samples using cloud-point extraction and cold vapor atomic absorption spectrometry is demonstrated. Before the extraction, the samples were submitted to microwave-assisted digestion in a mixture of H(2)O(2) and HNO(3). Cloud point extraction was carried out using 0.5% (m/v) ammonium O,O-diethyldithiophosphate (DDTP) as the chelating agent and 0.3% (m/v) Triton X-114 as the non-ionic surfactant. Phase separation was induced after the addition of Na(2)SO(4) to a final concentration of 0.2 mol L(-1). Aliquots of the final extract were transferred to PTFE tubes and NaBH(4) and HCl were added. The mercury vapor was driven to a non-heated quartz tube for measuring the absorbance. The results obtained with salt-induced phase separation were in good agreement with the certified values at a 95% confidence level. An enrichment factor of 10 allowed a detection limit of 0.4 ng g(-1) to be obtained, which demonstrates the high sensitivity of the proposed procedure for the determination of mercury at trace levels.

  9. Determination of Hg(II) in waters by on-line preconcentration using Cyanex 923 as a sorbent — Cold vapor atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Duan, Taicheng; Song, Xuejie; Xu, Jingwei; Guo, Pengran; Chen, Hangting; Li, Hongfei

    2006-09-01

    Using a solid phase extraction mini-column home-made from a neutral extractant Cyanex 923, inorganic Hg could be on-line preconcentrated and simultaneously separated from methyl mercury. The preconcentrated Hg (II) was then eluted with 10% HNO 3 and subsequently reduced by NaBH 4 to form Hg vapor before determination by cold vapor atomic absorption spectrometry (CVAAS). Optimal conditions for and interferences on the Hg preconcentration and measurement were at 1% HCl, for a 25 mL sample uptake volume and a 10 mL min - 1 sample loading rate. The detection limit was 0.2 ng L - 1 and much lower than that of conventional method (around 15.8 ng L - 1 ). The relative standard deviation (RSD) is 1.8% for measurements of 40 ng L - 1 of Hg and the linear working curve is from 20 to 2000 ng L - 1 (with a correlation coefficient of 0.9996). The method was applied in determination of inorganic Hg in city lake and deep well water (from Changchun, Jilin, China), and recovery test results for both samples were satisfactory.

  10. Role of Co-Vapors in Vapor Deposition Polymerization

    NASA Astrophysics Data System (ADS)

    Lee, Ji Eun; Lee, Younghee; Ahn, Ki-Jin; Huh, Jinyoung; Shim, Hyeon Woo; Sampath, Gayathri; Im, Won Bin; Huh, Yang–Il; Yoon, Hyeonseok

    2015-02-01

    Polypyrrole (PPy)/cellulose (PPCL) composite papers were fabricated by vapor phase polymerization. Importantly, the vapor-phase deposition of PPy onto cellulose was assisted by employing different co-vapors namely methanol, ethanol, benzene, water, toluene and hexane, in addition to pyrrole. The resulting PPCL papers possessed high mechanical flexibility, large surface-to-volume ratio, and good redox properties. Their main properties were highly influenced by the nature of the co-vaporized solvent. The morphology and oxidation level of deposited PPy were tuned by employing co-vapors during the polymerization, which in turn led to change in the electrochemical properties of the PPCL papers. When methanol and ethanol were used as co-vapors, the conductivities of PPCL papers were found to have improved five times, which was likely due to the enhanced orientation of PPy chain by the polar co-vapors with high dipole moment. The specific capacitance of PPCL papers obtained using benzene, toluene, water and hexane co-vapors was higher than those of the others, which is attributed to the enlarged effective surface area of the electrode material. The results indicate that the judicious choice and combination of co-vapors in vapor-deposition polymerization (VDP) offers the possibility of tuning the morphological, electrical, and electrochemical properties of deposited conducting polymers.

  11. VAPOR PRESSURES AND HEATS OF VAPORIZATION OF PRIMARY COAL TARS

    SciTech Connect

    Eric M. Suuberg; Vahur Oja

    1997-07-01

    This project had as its main focus the determination of vapor pressures of coal pyrolysis tars. It involved performing measurements of these vapor pressures and from them, developing vapor pressure correlations suitable for use in advanced pyrolysis models (those models which explicitly account for mass transport limitations). This report is divided into five main chapters. Each chapter is a relatively stand-alone section. Chapter A reviews the general nature of coal tars and gives a summary of existing vapor pressure correlations for coal tars and model compounds. Chapter B summarizes the main experimental approaches for coal tar preparation and characterization which have been used throughout the project. Chapter C is concerned with the selection of the model compounds for coal pyrolysis tars and reviews the data available to us on the vapor pressures of high boiling point aromatic compounds. This chapter also deals with the question of identifying factors that govern the vapor pressures of coal tar model materials and their mixtures. Chapter D covers the vapor pressures and heats of vaporization of primary cellulose tars. Chapter E discusses the results of the main focus of this study. In summary, this work provides improved understanding of the volatility of coal and cellulose pyrolysis tars. It has resulted in new experimentally verified vapor pressure correlations for use in pyrolysis models. Further research on this topic should aim at developing general vapor pressure correlations for all coal tars, based on their molecular weight together with certain specific chemical characteristics i.e. hydroxyl group content.

  12. Mercury determination in non- and biodegradable materials by cold vapor capacitively coupled plasma microtorch atomic emission spectrometry.

    PubMed

    Frentiu, Tiberiu; Mihaltan, Alin I; Ponta, Michaela; Darvasi, Eugen; Frentiu, Maria; Cordos, Emil

    2011-10-15

    A new analytical system consisting of a low power capacitively coupled plasma microtorch (20 W, 13.56 MHz, 150 ml min(-1) Ar) and a microspectrometer was investigated for the Hg determination in non- and biodegradable materials by cold-vapor generation, using SnCl(2) reductant, and atomic emission spectrometry. The investigated miniaturized system was used for Hg determination in recyclable plastics from electronic equipments and biodegradable materials (shopping bags of 98% biodegradable polyethylene and corn starch) with the advantages of easy operation and low analysis costs. Samples were mineralized in HNO(3)-H(2)SO(4) mixture in a high-pressure microwave system. The detection limits of 0.05 ng ml(-1) or 0.08 μg g(-1) in solid sample were compared with those reported for other analytical systems. The method precision was 1.5-9.4% for Hg levels of 1.37-13.9 mg kg(-1), while recovery in two polyethylene certified reference materials in the range 98.7 ± 4.5% (95% confidence level).

  13. Acid neutralization of precipitation in Northern China.

    PubMed

    Wang, Yuesi; Yu, Wenpeng; Pan, Yuepeng; Wu, Dan

    2012-02-01

    There is an increasing concern over the impact of human-related emissions on the acid precipitation in China. However, few measurements have been conducted so far to clarify the acid-neutralization of precipitation on a regional scale. Under a network of 10 sites across Northern China operated during a 3-year period from December 2007 to November 2010, a total of 1118 rain and snow samples were collected. Of this total, 28% was acid precipitation with pH < 5.6. Out of these acid samples, 53% were found heavily acidic with pH value below 5.0, indicating significantly high levels of acidification of precipitation. Most of the acidity of precipitation was caused by H2SO4 and HNO3, their relative contribution being 72% and 28%, respectively. However; the contribution of HNO3 to precipitation acidity will be enhanced due to the increasing NO(x) and stable SO2 emissions in future. Neutralization factors for K+, NH4+, Ca2+, Na+, and Mg2+ were estimated as 0.06, 0.71, 0.72, 0.15, and 0.13, respectively. The application of multiple regression analysis further quantified higher NH4+ and Ca2+ contribution to the neutralization process, but the dominant neutralizing agent varied from site to site. The neutralization was less pronounced in the rural than urban areas, probably due to different levels of alkaline species, which strongly buffered the acidity. Presence of high concentrations of basic ions was mainly responsible for high pH of precipitation with annual volume-weighted mean (VWM) values larger than 5.6 at several sites. It was estimated that in the absence of buffering ions, for the given concentration of SO4(2-) and NO3-, the annual VWM pH of precipitation would have been recorded around 3.5 across Northern China. This feature suggested that emissions of particles and gaseous NH3 played very important role in controlling the spatial variations of pH of precipitation in the target areas.

  14. Effects of acid on the microstructures and properties of three-dimensional TiO2 hierarchical structures by solvothermal method

    NASA Astrophysics Data System (ADS)

    Zhou, Jing; Song, Bin; Zhao, Gaoling; Han, Gaorong

    2012-04-01

    Three-dimensional (3D) TiO2 hierarchical structures with various microstructures have been successfully synthesized via a surfactant-free and single-step solvothermal route, in which hydrochloric acid (HCl), nitric acid (HNO3), and acetic acid (HAc) are employed as the acid medium, respectively. The effects of acid medium on the microstructures and properties of 3D TiO2 hierarchical structure have been studied. The results indicate that 3D dandelion-like microspheres assembled of radial rutile nanorods are obtained in the sample prepared with HCl. Both the fraction of rutile and the diameter of nanorod enhance with the increasing HCl concentration. For the products derived from either HNO3 or HAc, 3D spheres composed of anatase nanoparticles are present. The 3D dandelion-like TiO2 hierarchical structures show low reflectance and efficient light harvesting since this ordered rod geometry offers a light-transfer path for incident light as well as multiple reflective and scattering effects. Moreover, 3D TiO2 with this unique topology shows superior photocatalytic activity despite low surface area, which can be ascribed to the enhanced light harvesting, fast electron transport, and low electron/hole recombination loss.

  15. Effects of acid on the microstructures and properties of three-dimensional TiO2 hierarchical structures by solvothermal method

    PubMed Central

    2012-01-01

    Three-dimensional (3D) TiO2 hierarchical structures with various microstructures have been successfully synthesized via a surfactant-free and single-step solvothermal route, in which hydrochloric acid (HCl), nitric acid (HNO3), and acetic acid (HAc) are employed as the acid medium, respectively. The effects of acid medium on the microstructures and properties of 3D TiO2 hierarchical structure have been studied. The results indicate that 3D dandelion-like microspheres assembled of radial rutile nanorods are obtained in the sample prepared with HCl. Both the fraction of rutile and the diameter of nanorod enhance with the increasing HCl concentration. For the products derived from either HNO3 or HAc, 3D spheres composed of anatase nanoparticles are present. The 3D dandelion-like TiO2 hierarchical structures show low reflectance and efficient light harvesting since this ordered rod geometry offers a light-transfer path for incident light as well as multiple reflective and scattering effects. Moreover, 3D TiO2 with this unique topology shows superior photocatalytic activity despite low surface area, which can be ascribed to the enhanced light harvesting, fast electron transport, and low electron/hole recombination loss. PMID:22500985

  16. Study of the effect of the acid-base surface properties of ZnO, Fe{sub 2}O{sub 3} and ZnFe{sub 2}O{sub 4} oxides on their gas sensitivity to ethanol vapor

    SciTech Connect

    Karpova, S. S. Moshnikov, V. A.; Maksimov, A. I.; Mjakin, S. V.; Kazantseva, N. E.

    2013-08-15

    Binary (ZnO, Fe{sub 2}O{sub 3}) and ternary (ZnFe{sub 2}O{sub 4}) gas-sensitive oxide materials are synthesized, and the correlation between their sensitivity to ethanol vapor and the functional chemical composition of the surface is studied by X-ray photoelectron spectroscopy and by the technique of the adsorption of acid-base indicators. It is found that the sensitivity to ethanol increases with increasing content of Broensted acid sites with the acidity index pK{sub a} Almost-Equal-To 2.5 and with increasing percentage of surface oxygen involved in OH/CO{sub 3}/C-O groups. This interrelation is attributed to the specific features of interaction between ethanol molecules and hydroxyl groups on the surface of the oxides.

  17. The effects of acidic irrigation on soil microorganisms at Kevo, Northern Finland.

    PubMed

    Kytöviita, M M; Fritze, H; Neuvonen, S

    1990-01-01

    Effects of simulated acid rain (a mixture of H(2)SO(4) and HNO(3); pH(3)) on soil microbiology were studied in a field experiment in northern Finland. Irrigated control plots received the same amount of spring water (pH 6) as the acid treated plots. Fungal lengths and total bacterial numbers were studied after the treatments had continued for three growing seasons. The numbers of bacteria in five physiological groups (those utilizing starch, protein, pectin, xylan, or cellulose) were measured by MPN (most probable number) techniques. The lengths of total and FDA active fungal hyphae were not significantly different between the acid treated and the control plots. The counts of total bacteria were not significantly different between treatments, but the MPNs of all five physiological groups of bacteria were approximately 60% lower in the acid treated plots than in the controls.

  18. [Determination of Sb and Bi in 24 international geological reference materials by using pressurized acid digestion-ICP-MS].

    PubMed

    Hu, Zhao-chu; Gao, Shan; Liu, Xiao-ming; Yuan, Hong-lin; Liu, Ye; Diwu, Chun-rong

    2007-12-01

    The authors studied in detail the memory effect of Bi, Sb, As and Te in ICP-MS. The produced memory effects of these element were in the order of Bi>Sb>Te>As. Bi was seriously adsorbed by the polypropylene sample storing bottle and the sample introduction system in the low nitric acid medium (0.01%-1% HNO3). The washout effect of 0.1% HF was found to be better than those of 6% HNO3 and 0.1% HClO4. Under the given experiment conditions, the instrumental limit of detection was 0.001 and 0.0001 ng x mL(-1) for Sb and Bi, respectively. The authors report the determination of Sb and Bi in 24 international geological reference materials by using pressurized acid digestion-ICP-MS (including AGV-2, BHVO-2, BCR-2, etc.). Most of the results were found to be in reasonable agreement with the reported values in the literature. The authors' determined values of Sb for GSR-1 (granite; 0.30 microg x g(-1)) and JP-1 (peridotite; 0.045 microg x g(-1)) are obviously higher than those reported values. This is attributed to the efficient pressurized acid digestion, which is generally much more efficient than conventional wet digestions for insoluble minerals. PMID:18330312

  19. [Determination of Sb and Bi in 24 international geological reference materials by using pressurized acid digestion-ICP-MS].

    PubMed

    Hu, Zhao-chu; Gao, Shan; Liu, Xiao-ming; Yuan, Hong-lin; Liu, Ye; Diwu, Chun-rong

    2007-12-01

    The authors studied in detail the memory effect of Bi, Sb, As and Te in ICP-MS. The produced memory effects of these element were in the order of Bi>Sb>Te>As. Bi was seriously adsorbed by the polypropylene sample storing bottle and the sample introduction system in the low nitric acid medium (0.01%-1% HNO3). The washout effect of 0.1% HF was found to be better than those of 6% HNO3 and 0.1% HClO4. Under the given experiment conditions, the instrumental limit of detection was 0.001 and 0.0001 ng x mL(-1) for Sb and Bi, respectively. The authors report the determination of Sb and Bi in 24 international geological reference materials by using pressurized acid digestion-ICP-MS (including AGV-2, BHVO-2, BCR-2, etc.). Most of the results were found to be in reasonable agreement with the reported values in the literature. The authors' determined values of Sb for GSR-1 (granite; 0.30 microg x g(-1)) and JP-1 (peridotite; 0.045 microg x g(-1)) are obviously higher than those reported values. This is attributed to the efficient pressurized acid digestion, which is generally much more efficient than conventional wet digestions for insoluble minerals.

  20. Vapor Diffusion Apparatus

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Vapor Diffusion Apparatus (VDA and VDA-2) was developed by the University of Alabama in Birmingham for NASA's Marshall Space Flight Center. In the original VDA, a protein solution and a precipitant are extruded by two plungers onto the tip of a small syringe and allowed to evaporate, raising the concentration and prompting protein molecules to crystallize. In the VDA-2 version, a third plunger was added to mix the two solutions before returning the mix to the syringe tip. The principal investigator is Dr. Larry Delucas of the University of Alabama in Birmingham

  1. Vapor Diffusion Apparatus

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Vapor Diffusion Apparatus (VDA-2) was developed by the University of Alabama in Birmingham for NASA's Marshall Space Flight Center. In the original VDA, a protein solution and a precipitant are extruded by two plungers onto the tip of a small syringe and allowed to evaporate, raising the concentration and prompting protein molecules to crystallize. In the VDA-2 version, a third plunger was added to mix the two solutions before returning the mix to the syringe tip. The principal investigator is Dr. Larry Delucas of the University of Alabama in Birmingham.

  2. Uptake measurements of ethanol on ice surfaces and on supercooled aqueous solutions doped with nitric acid between 213 and 243 K.

    PubMed

    Kerbrat, M; Le Calvé, S; Mirabel, Ph

    2007-02-01

    Uptake of ethanol either on pure frozen ice surfaces or supercooled solutions doped with HNO3 (0.63 and 2.49 wt %) has been investigated using a coated wall flow tube coupled to a mass spectrometric detection. The experiments were conducted over the temperature range of 213-243 K. Uptake of ethanol on these surfaces was always found to be totally reversible whatever were the experimental conditions. The number of ethanol molecules adsorbed per surface unit was conventionally plotted as a function of ethanol concentration in the gas phase and subsequently analyzed using Langmuir's model. The amount of ethanol molecules taken up on nitric acid doped-ice surfaces was found to increase largely with increasing nitric acid concentrations. For example at 223 K, and for an ethanol gas-phase concentration of 1x10(13) molecules cm3, the number of adsorbed molecules are (in units of molecules cm-2): approximately 1.3x10(14) on pure ice; approximately 1.4x10(15) on ice doped with HNO3 0.63 wt %; approximately 7.5x10(15) on ice doped with HNO3, 2.49 wt %, i.e. 60 times larger than on pure ice. Since, according to the shape of the isotherms, the adsorption did not proceed beyond monolayer coverage, the enormous increase of ethanol uptake was explained by considering its dissolution in either a supercooled liquid layer (T<230 K) or a liquid solution (T>230 K). The formation of both was indeed favored by the presence of the HNO3. Our experimental results suggest that the amount of ethanol dissolved in such supercooled solutions follows Henry's law and that the Henry's law constants at low temperatures, i.e., 223-243 K, can be estimated by extrapolation from higher temperatures. Such supercooled solutions which exist in the troposphere either in deep convective clouds or in mixed clouds for temperature above 233 K, might be responsible for the scavenging of large amounts of soluble species, such as nitric and sulfuric acids, oxygenated VOCs including alcohols, carboxylic acids, and

  3. Electron beam targets vapor-phase contaminants

    SciTech Connect

    1995-07-01

    Electron-beam bombardment has long been known to break down complex molecules. Zapit Technology, Inc. (Santa Clara, California) is in the process of commercializing a treatment system, tested in conjunction with the Lawrence Livermore National Laboratory, which uses electron beams to destroy vapor-phase toxic wastes. Drawing relatively low-power beams, the system is said to offer a low-cost way to oxidize chlorinated and non-chlorinated organic compounds. The unit has been developed to treat vapor-phase organic wastes at temperatures less than 400 F, and at ambient pressures. Candidates streams include process of gases, and organics collected during soil-vapor extraction or stripped from wastewater and groundwater streams. Inside the Zapit treatment unit, a continuous stream of ionizing electrons is generated by a cathode and is accelerated to nearly the speed of light through a metal grid. As the pollutant stream passes through the reaction chamber, it is bombarded by this electron beam. In the process, complex organic molecules are broken down into water, carbon dioxide, and, if chlorinated compounds are present, hydrochloric acid. During groundwater treatment, an air stripper converts dissolved organics in a vapor phase, which is passed through the electron-beam unit. The offgases from the Zapit unit are passed through an acid scrubber (using sodium hydroxide) to neutralize any byproduct HCl and through a carbon-adsorption unit for final polishing. Industrial offgases can be fed directly into the Zapit treatment unit, without the intermediate air stripper. Electrical power requirements are relatively low.

  4. Effects of acid pre-treatment on bio-hydrogen production and microbial communities during dark fermentation.

    PubMed

    Lee, Myoung-Joo; Song, Ji-Hyeon; Hwang, Sun-Jin

    2009-02-01

    Optimal conditions for acid pre-treatment were investigated for the enrichment of hydrogen-producing bacteria (HPB) in a mixed culture using three strong acids: HCl, HNO(3), and H2SO4 x HCl was selected as a suitable acid for the enrichment of HPB in the fermentation process. The volume of bio-hydrogen produced when the mixed culture was pre-treated using HCl at pH 2 was 3.2 times higher than that obtained without acid pre-treatment. Changes in the microbial community during acid pre-treatment were monitored using images obtained by the fluorescent in situ hybridization (FISH) method and the Live/Dead cell viability test. The tests clearly indicated that the Clostridium species of cluster I were the predominant strains involved in bio-H(2) fermentation, and could be selectively enriched by HCl pre-treatment.

  5. Effect of simulated acid rain on quantity of epiphytic microfungi on Scots pine (Pinus sylvestris L.) needles.

    PubMed

    Ranta, H M

    1990-01-01

    The effects of simulated acid rain on the phyllosphere microflora of pine (Pinus sylvestris L.) were studied experimentally in northern Finland during the summer of 1988. Trees were irrigated with artificial acid rain of pH4 and pH3 (H(2)SO(4) and HNO(3), weight ratio of S:N=2.86:1). Untreated trees and trees irrigated with spring water (pH6) were used as controls. Two sampling heights (0.5m and 2m) were used. The needles were colonized exclusively by epiphytic fungi, mainly Aureobasidium pullulans (de Bary) Arnaud. The lower branches had significantly more epiphytic fungi than the upper branches. Compared to the control trees, the numbers of epiphytic fungi were significantly decreased on the needles of trees irrigated with acid rain. Acid rain affected the number of epiphytic fungi equally at both sampling heights. The species composition of the epiphytic fungi was not affected by the acid treatments.

  6. Vapor spill pipe monitor

    NASA Astrophysics Data System (ADS)

    Bianchini, G. M.; McRae, T. G.

    1983-06-01

    The invention is a method and apparatus for continually monitoring the composition of liquefied natural gas flowing from a spill pipe during a spill test by continually removing a sample of the LNG by means of a probe, gasifying the LNG in the probe, and sending the vaporized LNG to a remote IR gas detector for analysis. The probe comprises three spaced concentric tubes surrounded by a water jacket which communicates with a flow channel defined between the inner and middle, and middle and outer tubes. The inner tube is connected to a pump for providing suction, and the probe is positioned in the LNG flow below the spill pipe with the tip oriented partly downward so that LNG is continuously drawn into the inner tube through a small orifice. The probe is made of a high thermal conductivity metal. Hot water is flowed through the water jacket and through the flow channel between the three tubes to provide the necessary heat transfer to flash vaporize the LNG passing through the inner channel of the probe. The gasified LNG is transported through a connected hose or tubing extending from the probe to a remote IR sensor which measures the gas composition.

  7. Vapor spill pipe monitor

    DOEpatents

    Bianchini, G.M.; McRae, T.G.

    1983-06-23

    The invention is a method and apparatus for continually monitoring the composition of liquefied natural gas flowing from a spill pipe during a spill test by continually removing a sample of the LNG by means of a probe, gasifying the LNG in the probe, and sending the vaporized LNG to a remote ir gas detector for analysis. The probe comprises three spaced concentric tubes surrounded by a water jacket which communicates with a flow channel defined between the inner and middle, and middle and outer tubes. The inner tube is connected to a pump for providing suction, and the probe is positioned in the LNG flow below the spill pipe with the tip oriented partly downward so that LNG is continuously drawn into the inner tube through a small orifice. The probe is made of a high thermal conductivity metal. Hot water is flowed through the water jacket and through the flow channel between the three tubes to provide the necessary heat transfer to flash vaporize the LNG passing through the inner channel of the probe. The gasified LNG is transported through a connected hose or tubing extending from the probe to a remote ir sensor which measures the gas composition.

  8. Two-dimensional correlation analysis to study variation of near-infrared water absorption bands in the presence of inorganic acids

    NASA Astrophysics Data System (ADS)

    Chang, Kyeol; Jung, Young Mee; Chung, Hoeil

    2014-07-01

    Two-dimensional (2D) correlation analysis has been utilized to investigate NIR water bands perturbed by the presence of four different inorganic acids individually: HCl, H2SO4, H3PO4, and HNO3. The observed spectral variation in the 9000-7700 cm-1 range was mainly due to interaction of dissociated H3O+ and corresponding anions with the vibration of water in a hydrogen bonding network. 2D correlation analysis of NIR spectra acquired from sample solutions (concentration range: 0.2-1.0 M) showed that individual acids differently influenced water vibration. In addition, unforeseen spectral variations under the water band that were difficult to identify with corresponding raw NIR spectra were clearly observed. Based on the asynchronous correlation analysis, three underlying individual variations occurred for HCl under the 8718 cm-1 band. Only two asynchronous correlations were observed for H2SO4 and H3PO4. The 2D correlation features of HNO3 were distinctly different from those of the other three acids due to an additional spectral feature caused by direct absorption by NO3-. The dissimilar influence of the selected acids on water vibration was confirmed by NIR spectroscopy combined with 2D correlation analysis. Partial least squares (PLS) loadings from each case were compared to examine the difference in weights that were constructed to follow the corresponding concentration changes.

  9. Vapor pressures of a homologous series of polyethylene glycols as a reference data set for validating vapor pressure measurement techniques.

    NASA Astrophysics Data System (ADS)

    Krieger, Ulrich; Marcolli, Claudia; Siegrist, Franziska

    2015-04-01

    The production of secondary organic aerosol (SOA) by gas-to-particle partitioning is generally represented by an equilibrium partitioning model. A key physical parameter which governs gas-particle partitioning is the pure component vapor pressure, which is difficult to measure for low- and semivolatile compounds. For typical atmospheric compounds like e.g. citric acid or tartaric acid, vapor pressures have been reported in the literature which differ by up to six orders of magnitude [Huisman et al., 2013]. Here, we report vapor pressures of a homologous series of polyethylene glycols (triethylene glycol to octaethylene glycol) determined by measuring the evaporation rate of single, levitated aerosol particles in an electrodynamic balance. We propose to use those as a reference data set for validating different vapor pressure measurement techniques. With each addition of a (O-CH2-CH2)-group the vapor pressure is lowered by about one order of magnitude which makes it easy to detect the lower limit of vapor pressures accessible with a particular technique down to a pressure of 10-8 Pa at room temperature. Reference: Huisman, A. J., Krieger, U. K., Zuend, A., Marcolli, C., and Peter, T., Atmos. Chem. Phys., 13, 6647-6662, 2013.

  10. Field comparison of methods for the measurement of gaseous and particulate contributors to acidic dry deposition

    SciTech Connect

    Sickles, J.E.; Hodson, L.L.; McClenny, W.A.; Paur, R.J.; Ellestad, T.G.

    1990-01-01

    A field study was conducted to compare methods for sampling and analysis of atmospheric constituents that are important contributors to acidic dry deposition. Three multicomponent samplers were used: the Canadian filter pack (FP), the annular denuder system (ADS), and the transition flow reactor (TFR). A tunable diode laser absorption spectrometer (TDLAS) provided continuous reference measurements of NO2 and HNO3. Nitrogen dioxide was also monitored with continuous luminol-based chemiluminescence monitors and with passive sampling devices (PSDs). The study was designed to provide a database for statistical comparison of the various methods with emphasis on the multicomponent samplers under consideration for use in a national dry deposition network. The study was conducted at the EPA dry deposition station in Research Triangle Park, NC between 29 September and 12 October, 1986. Daily averaging and/or sampling times were employed for the 13-day study; weekly samples were also collected, but results from these samples are not compared in the paper. Different measurements of ambient concentrations of the following constituents are compared: total particulate and gaseous NO3(-), HNO3, NO2, total particulate NH4(-), NH3, total particulate SO4(-), and SO2.

  11. Adsorption study of acetone on acid-doped ice surfaces between 203 and 233 K.

    PubMed

    Journet, E; Le Calvé, S; Mirabel, Ph

    2005-07-28

    Adsorption studies of acetone on pure ice surfaces obtained by water freezing or deposition or on frozen ice surfaces doped either with HNO3 or H2SO4 have been performed using a coated wall flow tube coupled to a mass spectrometric detection. The experiments were conducted over the temperature range 203-233 K and freezing solutions containing either H2SO4 (0.2 N) or HNO3 (0.2-3 N). Adsorption of acetone on these ice surfaces was always found to be totally reversible whatever were the experimental conditions. The number of acetone molecules adsorbed per ice surface unit N was conventionally plotted as a function of acetone concentration in the gas phase. For the same conditions, the amount of acetone molecules adsorbed on pure ice obtained by deposition are about 3-4 times higher than those measured on frozen ice films, H2SO4-doped ice surfaces lead to results comparable to those obtained on pure ice. On the contrary, N increases largely with increasing concentrations of nitric acid in ice surfaces, up to about 300 times under our experimental conditions and for temperatures ranging between 213 and 233 K. Finally, the results are discussed and used to reestimate the partitioning of acetone between the ice and gas phases in clouds of the upper troposphere.

  12. Iron bromide vapor laser

    NASA Astrophysics Data System (ADS)

    Sukhanov, V. B.; Shiyanov, D. V.; Trigub, M. V.; Dimaki, V. A.; Evtushenko, G. S.

    2016-03-01

    We have studied the characteristics of a pulsed gas-discharge laser on iron bromide vapor generating radiation with a wavelength of 452.9 nm at a pulse repetition frequency (PRF) of 5-30 kHz. The maximum output power amounted to 10 mW at a PRF within 5-15 kHz for a voltage of 20-25 kV applied to electrodes of the discharge tube. Addition of HBr to the medium produced leveling of the radial profile of emission. Initial weak lasing at a wavelength of 868.9 nm was observed for the first time, which ceased with buildup of the main 452.9-nm line.

  13. Chemical vapor deposition growth

    NASA Technical Reports Server (NTRS)

    Ruth, R. P.; Manasevit, H. M.; Kenty, J. L.; Moudy, L. A.; Simpson, W. I.; Yang, J. J.

    1976-01-01

    The chemical vapor deposition (CVD) method for the growth of Si sheet on inexpensive substrate materials is investigated. The objective is to develop CVD techniques for producing large areas of Si sheet on inexpensive substrate materials, with sheet properties suitable for fabricating solar cells meeting the technical goals of the Low Cost Silicon Solar Array Project. Specific areas covered include: (1) modification and test of existing CVD reactor system; (2) identification and/or development of suitable inexpensive substrate materials; (3) experimental investigation of CVD process parameters using various candidate substrate materials; (4) preparation of Si sheet samples for various special studies, including solar cell fabrication; (5) evaluation of the properties of the Si sheet material produced by the CVD process; and (6) fabrication and evaluation of experimental solar cell structures, using standard and near-standard processing techniques.

  14. Vapor compression distillation module

    NASA Technical Reports Server (NTRS)

    Nuccio, P. P.

    1975-01-01

    A Vapor Compression Distillation (VCD) module was developed and evaluated as part of a Space Station Prototype (SSP) environmental control and life support system. The VCD module includes the waste tankage, pumps, post-treatment cells, automatic controls and fault detection instrumentation. Development problems were encountered with two components: the liquid pumps, and the waste tank and quantity gauge. Peristaltic pumps were selected instead of gear pumps, and a sub-program of materials and design optimization was undertaken leading to a projected life greater than 10,000 hours of continuous operation. A bladder tank was designed and built to contain the waste liquids and deliver it to the processor. A detrimental pressure pattern imposed upon the bladder by a force-operated quantity gauge was corrected by rearranging the force application, and design goals were achieved. System testing has demonstrated that all performance goals have been fulfilled.

  15. THERMALLY OPERATED VAPOR VALVE

    DOEpatents

    Dorward, J.G. Jr.

    1959-02-10

    A valve is presented for use in a calutron to supply and control the vapor to be ionized. The invention provides a means readily operable from the exterior of the vacuum tank of the apparatuss without mechanical transmission of forces for the quick and accurate control of the ionizing arc by a corresponding control of gas flow theretos thereby producing an effective way of carefully regulating the operation of the calutron. The invention consists essentially of a tube member extending into the charge bottle of a calutron devices having a poppet type valve closing the lower end of the tube. An electrical heating means is provided in the valve stem to thermally vary the length of the stem to regulate the valve opening to control the flow of material from the charge bottle.

  16. Progress, prospects, and research needs on the health effects of acid aerosols.

    PubMed

    Lippmann, M

    1989-02-01

    Research on human exposure to acidic aerosols and the health effects of such exposures has substantially strengthened the hypothesis that such aerosols are a causal factor for excesses in human mortality and morbidity that have been previously associated with crude exposure indices such as British Smoke, total suspended particulate matter, and sulfur dioxide. Research reported at this symposium also showed that combined exposures to acid aerosols and other ubiquitous air pollutants such as O3, NO2, HNO3, and SO2 produce greater effects in both humans and animals than exposures to each agent separately. The responses reported ranged from physiological functions to lung structure. Furthermore, some of the effects were cumulative with increasing duration of daily exposure and number of repetitive exposures. Critical areas for further research include better definition of the critical temporal parameters affecting exposure and response, effects of mixed pollutant exposures, and pathogenetic mechanisms for acid aerosol-induced chronic lung damage.

  17. Detection of explosives, narcotics, and taggant vapors by an ion mobility spectrometry particle detector

    NASA Astrophysics Data System (ADS)

    Ritchie, Robert K.; Thomson, Paul C.; DeBono, Reno F.; Danylewich-May, Lucy L.; Kim, Lena

    1994-03-01

    Methods of analyzing vapors in an IMS explosives/narcotics detector that is primarily designed for particle collection were investigated, with emphasis on nitroglycerin explosive, and acetic and benzoic acid contaminants in narcotics. A preconcentration step is required because expected vapor concentrations are low. NG adsorption and retention behavior on coated teflon filters that are compatible with the IMS sample desorption system is reported, including the effects of adsorbent, and sampling flow rate, time and volume. Similar investigations were carried out for acetic and benzoic acid vapors, and a gold-plated nickel mesh was selected as the most appropriate IMS-compatible filter for these materials. Vapor sampling flow rates and volumes are much lower than those used in particle sampling. Examples of NG and benzoic acid vapor detection in real and simulated applications are discussed.

  18. Constrained Vapor Bubble

    NASA Technical Reports Server (NTRS)

    Huang, J.; Karthikeyan, M.; Plawsky, J.; Wayner, P. C., Jr.

    1999-01-01

    The nonisothermal Constrained Vapor Bubble, CVB, is being studied to enhance the understanding of passive systems controlled by interfacial phenomena. The study is multifaceted: 1) it is a basic scientific study in interfacial phenomena, fluid physics and thermodynamics; 2) it is a basic study in thermal transport; and 3) it is a study of a heat exchanger. The research is synergistic in that CVB research requires a microgravity environment and the space program needs thermal control systems like the CVB. Ground based studies are being done as a precursor to flight experiment. The results demonstrate that experimental techniques for the direct measurement of the fundamental operating parameters (temperature, pressure, and interfacial curvature fields) have been developed. Fluid flow and change-of-phase heat transfer are a function of the temperature field and the vapor bubble shape, which can be measured using an Image Analyzing Interferometer. The CVB for a microgravity environment, has various thin film regions that are of both basic and applied interest. Generically, a CVB is formed by underfilling an evacuated enclosure with a liquid. Classification depends on shape and Bond number. The specific CVB discussed herein was formed in a fused silica cell with inside dimensions of 3x3x40 mm and, therefore, can be viewed as a large version of a micro heat pipe. Since the dimensions are relatively large for a passive system, most of the liquid flow occurs under a small capillary pressure difference. Therefore, we can classify the discussed system as a low capillary pressure system. The studies discussed herein were done in a 1-g environment (Bond Number = 3.6) to obtain experience to design a microgravity experiment for a future NASA flight where low capillary pressure systems should prove more useful. The flight experiment is tentatively scheduled for the year 2000. The SCR was passed on September 16, 1997. The RDR is tentatively scheduled for October, 1998.

  19. Kinetics of the reaction of hydroxyl radicals with nitric acid

    NASA Technical Reports Server (NTRS)

    Margitan, J. J.; Watson, R. T.

    1982-01-01

    An extensive study was made of the reaction of hydroxyl radicals with nitric acid in a laser photolysis-resonance fluorescence system. A 266 nm laser was used to photolyze HNO3 in the temperature range 225-415 K at pressures of 20-300 torr. A temperature dependence was detected below room temperature, with a leveling off at 298 K and a wide spread in the rate constants. A pressure dependence was observed over the entire range and was more pronounced at lower temperatures. The results are noted to be in agreement with those of previous investigations. However, the wide range of rate constants are suggested to be a problem for stratospheric HO(x) modeling for anthropogenic effects. No explanation could be given of the varying results obtained by other investigators regarding the kinetics of the reactions.

  20. Student Exposure to Mercury Vapors.

    ERIC Educational Resources Information Center

    Weber, Joyce

    1986-01-01

    Discusses the problem of mercury vapors caused by spills in high school and college laboratories. Describes a study which compared the mercury vapor levels of laboratories in both an older and a newer building. Concludes that the mercurial contamination of chemistry laboratories presents minimal risks to the students. (TW)

  1. Vapor pressure measured with inflatable plastic bag

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Deflated plastic bag in a vacuum chamber measures initial low vapor pressures of materials. The bag captures the test sample vapors and visual observation of the vapor-inflated bag under increasing external pressures yields pertinent data.

  2. Tested Demonstrations. Gasoline Vapor: An Invisible Pollutant

    ERIC Educational Resources Information Center

    Stephens, Edgar R.

    1977-01-01

    Describes a demonstration concerning the air pollution aspects of gasoline vapor which provides an estimation of the vapor pressure of test fuel, the molecular weight of the vapor, and illustrates a method of controlling the pollution. (SL)

  3. Biofiltration of solvent vapors from air

    SciTech Connect

    Oh, Young-sook.

    1993-01-01

    For various industrial solvent vapors, biofiltration promises to offer a cost-effective emission control technology. Exploiting the full potential of this technology will help attain the goals of the Clean Air Act Amendments of 1990. Concentrating on large volumes of volatile industrial solvents, stable multicomponent microbial enrichments capable of growing a mineral medium with solvent vapors as their only source of carbon and energy were obtained from soil and sewage sludge. These consortia were immobilized on an optimized porous solid support (ground peat moss and perlite). The biofilter material was packed in glass columns connected to an array of pumps and flow meters that allowed the independent variation of superficial velocity and solvent vapor concentrations. In various experiments, single solvents, such as methanol, butanol, acetonitrile, hexane and nitrobenzene, and solvent mixtures, such as benzene-toluene-xylene (BTX) and chlorobenzene-o-dichlorobenzene (CB/DCB) were biofiltered with rates ranging from 15 to334 g solvent removed per m[sup 3] filter volume /h. Pressure drops were low to moderate (0-10 mmHg/m) and with periodic replacement of moisture, the biofiltration activity could be maintained for a period of several months. The experimental data on methanol biofiltration were subjected to mathematical analysis and modeling by the group of Dr. Baltzis at NJIT for a better understanding and a possible scale up of solvent vapor biofilters. In the case of chlorobenzenes and nitrobenzene, the biofilter columns had to be operated with water recirculation in a trickling filter mode. To prevent inactivation of the trickling filter by acidity during CB/DCB removal, pH control was necessary, and the removal rate of CB/DCB was strongly influenced by the flow rate of the recyling water. Nitrobenzene removal in a trickling filter did not require pH control, since the nitro group was reduced and volatilized as ammonia.

  4. Dilute nitric or nitrous acid solution containing halide ions as effective media for pure gold dissolution.

    PubMed

    Hojo, Masashi; Yamamoto, Masahiko; Okamura, Kei

    2015-08-14

    The greatly enhanced oxidation ability of dilute aqueous nitric acid (0.10-2.0 mol L(-1)) containing bromide and iodide salts as well as chloride salts has been examined based on the dissolution kinetics of pure gold at 30-60 °C. It has been found that bromide salts are more effective than chloride salts in gaining the ability of dissolving gold in dilute aqueous nitric acid solution. At 60 °C, a piece of gold-wire (ca. 20 mg) is dissolved in 20 mL of as low as 0.10 mol L(-1) HNO3 solution containing 1.0-5.0 mol L(-1) NaBr and the dissolution rate constant, log(k/s(-1)), increases linearly (from -5.78 to -4.52) with the increasing NaBr concentration. The addition of organic solvents, such as acetonitrile and acetic acid, causes acceleration of gold dissolution in LiBr and NaBr solutions. With increasing MeCN contents, for instance, the log(k/s(-1)) value of 0.10 mol L(-1) HNO3 solution containing 2.0 mol L(-1) NaBr increases linearly from -5.30 to -4.61 at 30% (v/v) MeCN. The bromide salts affect the gold dissolution rate constant in the order of KBr < NaBr < LiBr < CaBr2. With increasing NaI concentration (0.20-3.0 mol L(-1)), some acceleration in log(k/s(-1)) of 0.50 or 1.0 mol L(-1) HNO3 solution has been observed; however, the slope of acceleration as the function of NaI concentration is much smaller than that of NaCl or NaBr. The gold dissolution ability has been examined also for nitrous acid containing chloride and bromide ions at 35 °C. The NaNO2 solution containing twice or more amounts of HX (X = Cl, Br) gives the maximum efficiency for gold dissolution, according to the log(k/s(-1)) values of the mixed solutions of NaNO2 (0.10-2.0 mol L(-1)) and HX of various concentrations. The influence of oxidation by dilute nitric and nitrous acids on the gold dissolution is discussed from the standpoint of the redox potentials in "modified" aqueous solutions and not of the changes in the activity coefficients of ions.

  5. Vapor Pressure, Vapor Composition and Fractional Vaporization of High Temperature Lavas on Io

    NASA Technical Reports Server (NTRS)

    Fegley, B., Jr.; Schaefer, L.; Kargel, J. S.

    2003-01-01

    Observations show that Io's atmosphere is dominated by SO2 and other sulfur and sulfur oxide species, with minor amounts of Na, K, and Cl gases. Theoretical modeling and recent observations show that NaCl, which is produced volcanically, is a constituent of the atmosphere. Recent Galileo, HST and ground-based observations show that some volcanic hot spots on Io have extremely high temperatures, in the range 1400-1900 K. At similar temperatures in laboratory experiments, molten silicates and oxides have significant vapor pressures of Na, K, SiO, Fe, Mg, and other gases. Thus vaporization of these species from high temperature lavas on Io seems likely. We therefore modeled the vaporization of silicate and oxide lavas suggested for Io. Our results for vapor chemistry are reported here. The effects of fractional vaporization on lava chemistry are given in a companion abstract by Kargel et al.

  6. CORRECTION FACTORS FOR COVARIANCE BETWEEN CONCENTRATION AND DEPOSITION VELOCITY ON CASTNET HNO3 DEPOSITION ESTIMATES

    EPA Science Inventory

    The covariance between hourly concentration (C) and deposition velocity (V) for various atmospheric; species may act to bias the, deposition (D) computed from the product of the weekly average C and 'V. This is a potential problem for the CASTNet filter pack (FP) species, nitric...

  7. Quantifying vapor drift of dicamba herbicides applied to soybean.

    PubMed

    Egan, J Franklin; Mortensen, David A

    2012-05-01

    Recent advances in biotechnology have produced cultivars of corn, soybean, and cotton resistant to the synthetic-auxin herbicide dicamba. This technology will allow dicamba herbicides to be applied in new crops, at new periods in the growing season, and over greatly expanded areas, including postemergence applications in soybean. From past and current use in corn and small grains, dicamba vapor drift and subsequent crop injury to sensitive broadleaf crops has been a frequent problem. In the present study, the authors measured dicamba vapor drift in the field from postemergence applications to soybean using greenhouse-grown soybean as a bioassay system. They found that when the volatile dimethylamine formulation is applied, vapor drift could be detected at mean concentrations of 0.56 g acid equivalent dicamba/ha (0.1% of the applied rate) at 21 m away from a treated 18.3 × 18.3 m plot. Applying the diglycolamine formulation of dicamba reduced vapor drift by 94.0%. With the dimethylamine formulation, the extent and severity of vapor drift was significantly correlated with air temperature, indicating elevated risks if dimethylamine dicamba is applied early to midsummer in many growing regions. Additional research is needed to more fully understand the effects of vapor drift exposures to nontarget crops and wild plants. PMID:22362509

  8. The lithium vapor box divertor

    NASA Astrophysics Data System (ADS)

    Goldston, R. J.; Myers, R.; Schwartz, J.

    2016-02-01

    It has long been recognized that volumetric dissipation of the plasma heat flux from a fusion power system is preferable to its localized impingement on a material surface. Volumetric dissipation mitigates both the anticipated very high heat flux and intense particle-induced damage due to sputtering. Recent projections to a tokamak demonstration power plant suggest an immense upstream parallel heat flux, of order 20 GW m-2, implying that fully detached operation may be a requirement for the success of fusion power. Building on pioneering work on the use of lithium by Nagayama et al and by Ono et al as well as earlier work on the gas box divertor by Watkins and Rebut, we present here a concept for a lithium vapor box divertor, in which lithium vapor extracts momentum and energy from a fusion-power-plant divertor plasma, using fully volumetric processes. At the high powers and pressures that are projected this requires a high density of lithium vapor, which must be isolated from the main plasma in order to avoid lithium build-up on the chamber walls or in the plasma. Isolation is achieved through a powerful multi-box differential pumping scheme available only for condensable vapors. The preliminary box-wise calculations are encouraging, but much more work is required to demonstrate the practical viability of this scheme, taking into account at least 2D plasma and vapor flows within and between the vapor boxes and out of the vapor boxes to the main plasma.

  9. The chemistry of gaseous acids in medieval churches in Cyprus

    NASA Astrophysics Data System (ADS)

    Loupa, G.; Charpantidou, E.; Karageorgos, E.; Rapsomanikis, S.

    Indoor and outdoor concentrations of HCl, HNO 3, HCOOH and CH 3COOH were determined in two medieval churches in Cyprus, during July 2003 and March 2004. The high air exchange rate through the open windows and doors led to lower indoor, compared to outdoor, acid concentrations in July 2003. Indoor pollutant emissions and a low air exchange rate resulted in higher indoor compared to outdoors acid concentrations in both churches during March 2004. Indoor to outdoor inorganic acid ratios were higher than the corresponding indoor to outdoor organic acid ratios during July 2003, whilst the opposite trend was observed during March 2004. Direct acid emission from candle burning appears to play a major role in the observed indoor acid concentrations. Emissions of volatile organic compounds from other sources, like humans, cleaning products and incense, led also to formation or depletion of the gaseous acids via homogeneous photochemical, heterogeneous and dark reaction sequences. Chemical reaction pathways were extensively investigated and appear to explain the observed results. The apparent indoor acid deposition velocities ranged between 0.05 and 0.15 cm s -1.

  10. Supercritical microgravity droplet vaporization

    NASA Technical Reports Server (NTRS)

    Hartfield, J.; Curtis, E.; Farrell, P.

    1990-01-01

    Supercritical droplet vaporization is an important issue in many combustion systems, such as liquid fueled rockets and compression-ignition (diesel) engines. In order to study the details of droplet behavior at these conditions, an experiment was designed to provide a gas phase environment which is above the critical pressure and critical temperature of a single liquid droplet. In general, the droplet begins as a cold droplet in the hot, high pressure environment. In order to eliminate disruptions to the droplet by convective motion in the gas, forced and natural convection gas motion are required to be small. Implementation of this requirement for forced convection is straightforward, while reduction of natural convection is achieved by reduction in the g-level for the experiment. The resulting experiment consists of a rig which can stably position a droplet without restraint in a high-pressure, high temperature gas field in microgravity. The microgravity field is currently achieved by dropping the device in the NASA Lewis 2.2 second drop tower. The performance of the experimental device and results to date are presented.

  11. Chemical vapor deposition growth

    NASA Technical Reports Server (NTRS)

    Ruth, R. P.; Manasevit, H. M.; Campbell, A. G.; Johnson, R. E.; Kenty, J. L.; Moudy, L. A.; Shaw, G. L.; Simpson, W. I.; Yang, J. J.

    1978-01-01

    The objective was to investigate and develop chemical vapor deposition (CVD) techniques for the growth of large areas of Si sheet on inexpensive substrate materials, with resulting sheet properties suitable for fabricating solar cells that would meet the technical goals of the Low Cost Silicon Solar Array Project. The program involved six main technical tasks: (1) modification and test of an existing vertical-chamber CVD reactor system; (2) identification and/or development of suitable inexpensive substrate materials; (3) experimental investigation of CVD process parameters using various candidate substrate materials; (4) preparation of Si sheet samples for various special studies, including solar cell fabrication; (5) evaluation of the properties of the Si sheet material produced by the CVD process; and (6) fabrication and evaluation of experimental solar cell structures, using impurity diffusion and other standard and near-standard processing techniques supplemented late in the program by the in situ CVD growth of n(+)/p/p(+) sheet structures subsequently processed into experimental cells.

  12. Multiwavelength Strontium Vapor Lasers

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Yudin, N. A.

    2016-08-01

    Based on an analysis of experimental and theoretical works, modern notion on conditions of forming of population density inversion on self-terminating IR transitions of alkali-earth metals is given. It is demonstrated that there is a significant difference in the inversion formation in lasers on self-terminating transitions in the visible and near-IR ranges and lasers on self-terminating transitions of alkali-earth metals lasing IR lines in the mid-IR range. It is shown that in the discharge circuit of lasers on self-terminating metal atom transitions (LSMT) there are processes strengthening the influence of the known mechanism limiting the frequency and energy characteristics (FEC) of radiation caused by the presence of prepulse electron concentration. The mechanism of influence of these processes on FEC of the LSMT and technical methods of their neutralization are considered. The possibility of obtaining average lasing power of ~200 W from one liter volume of the active medium of the strontium vapor laser is demonstrated under conditions of neutralization of these processes.

  13. VAPOR SHIELD FOR INDUCTION FURNACE

    DOEpatents

    Reese, S.L.; Samoriga, S.A.

    1958-03-11

    This patent relates to a water-cooled vapor shield for an inductlon furnace that will condense metallic vapors arising from the crucible and thus prevent their condensation on or near the induction coils, thereby eliminating possible corrosion or shorting out of the coils. This is accomplished by placing, about the top, of the crucible a disk, apron, and cooling jacket that separates the area of the coils from the interior of the cruclbIe and provides a cooled surface upon whlch the vapors may condense.

  14. Precision ozone vapor pressure measurements

    NASA Technical Reports Server (NTRS)

    Hanson, D.; Mauersberger, K.

    1985-01-01

    The vapor pressure above liquid ozone has been measured with a high accuracy over a temperature range of 85 to 95 K. At the boiling point of liquid argon (87.3 K) an ozone vapor pressure of 0.0403 Torr was obtained with an accuracy of + or - 0.7 percent. A least square fit of the data provided the Clausius-Clapeyron equation for liquid ozone; a latent heat of 82.7 cal/g was calculated. High-precision vapor pressure data are expected to aid research in atmospheric ozone measurements and in many laboratory ozone studies such as measurements of cross sections and reaction rates.

  15. Influence of crustal dust and sea spray supermicron particle concentrations and acidity on inorganic NO3- aerosol during the 2013 Southern Oxidant and Aerosol Study

    SciTech Connect

    Allen, Hannah M.; Draper, Danielle C.; Ayres, Benjamin R.; Ault, Andrew P.; Bondy, Amy L.; Takahama, S.; Modini, Robert; Baumann, K.; Edgerton, Eric S.; Knote, Christoph; Laskin, Alexander; Wang, Bingbing; Fry, Juliane L.

    2015-09-25

    The inorganic aerosol composition was measured in the southeastern United States, a region that exhibits high aerosol mass loading during the summer, as part of the 1 June to 15 July 2013 Southern Oxidant and Aerosol Study (SOAS) campaign. Measurements using a Monitor for AeRosols and GAses (MARGA), an ion chromatograph coupled with a wet rotating denuder and a steam-jet aerosol collector for monitoring of ambient inorganic gas and aerosol species, revealed two periods of high aerosol nitrate (NO3 ) concentrations during the campaign. These periods of high nitrate were correlated with increased concentrations of coarse mode mineral or sea spray aerosol species, particularly Na+ and Ca2+, and with a shift towards aerosol with larger (1 to 2.5 um) diameters. We suggest this nitrate aerosol forms by multiphase reactions of HNO3 and particles, reactions that are facilitated by transport of mineral dust and sea spray aerosol from a source within the United States. The observed high aerosol acidity prevents the formation of NH4NO3, the inorganic nitrogen species often dominant in fine-mode aerosol at higher pH. Calculation of the rate of the heterogeneous uptake of HNO3 on mineral aerosol supports the conclusion that aerosol NO3 is produced primarily by this process, and is likely limited by the availability of mineral dust surface area. Modeling of NO3 and HNO3 by thermodynamic equilibrium models (ISORROPIA II and E-AIM) reveals the importance of including mineral cations in the southeastern United States to accurately balance ion species and predict gas/aerosol phase partitioning.

  16. Heterogeneous reactions of gaseous hydrogen peroxide on pristine and acidic gas-processed calcium carbonate particles: Effects of relative humidity and surface coverage of coating

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Chen, Zhongming; Shen, Xiaoli; Huang, Dao

    2013-03-01

    Atmospheric aging appears to alter physical and chemical properties of mineral dust aerosol and thus its role as reactive surface in the troposphere. Yet, previous studies in the atmosphere have mainly focused on the pristine surfaces of mineral dust aerosol, and the reactivity of aged mineral dust toward atmospheric trace gases is poorly recognized. This work presents the first laboratory investigation of heterogeneous reactions of gaseous hydrogen peroxide (H2O2), an important atmospheric oxidant, on the surfaces of HNO3 and SO2-processed calcium carbonate particles as surrogates of atmospheric mineral dust aged by acidic trace gases. It is found that the processing of the calcium carbonate particles with HNO3 and SO2 has a strong impact on their reactivity toward H2O2. On HNO3-processed particles, the presence of nitrate acts to either decrease or increase H2O2 uptake, greatly depending on RH and surface coverage of nitrate. On SO2-processed particles, the presence of surface sulfite appears to enhance the intrinsic reactivity of the mineral particles due to its affinity for H2O2, and the uptake of H2O2 increases significantly relative to the pristine particles, in particular at high RH. The mechanisms for heterogeneous reactions of H2O2 with these processed particles are discussed, as well as their potential implications on tropospheric chemistry. The results of our study suggest that the reactivity of mineral dust aerosol toward H2O2 and maybe other trace gases is markedly dependent on the chemical composition and coverage of the coatings as well as ambient RH, and thus will vary considerably in different polluted air masses.

  17. Chemical Vapor Deposition of Polybenzoxazole Precursors

    NASA Astrophysics Data System (ADS)

    Anthamatten, Mitchell

    2005-03-01

    Polybenzoxazoles are well known for their outstanding thermal and mechanical properties. We will describe a new solventless, chemical vapor deposition approach to fabricating films of high strength polybenzoxazoles. Advantages of such an approach are: 1) control of film thickness, 2) conformal coating onto substrates, and 3) potential improvement of in-plane mechanical properties. Our process involves the vacuum evaporation of two monomers: a hydroxyl-functionalized diamine (DHB) and a dianhydride (PMDA). The resulting films appear uniform and contain poly(amic acid) linkages. FTIR experiments show that the poly(amic acid) converts to a polyimide material upon curing at 150 to 200 degrees C. At higher temperatures there is evidence that benzoxazole linkages form, though, interestingly, we also observe a concomitant decrease in the film's mass. Our current studies aim at understanding these high-temperature processes and how they impact the polymer's crystallinity and mechanical properties.

  18. Liquid-phase and vapor-phase dehydration of organic/water solutions

    DOEpatents

    Huang, Yu; Ly, Jennifer; Aldajani, Tiem; Baker, Richard W.

    2011-08-23

    Processes for dehydrating an organic/water solution by pervaporation or vapor separation using fluorinated membranes. The processes are particularly useful for treating mixtures containing light organic components, such as ethanol, isopropanol or acetic acid.

  19. Medicinal Cannabis: In Vitro Validation of Vaporizers for the Smoke-Free Inhalation of Cannabis.

    PubMed

    Lanz, Christian; Mattsson, Johan; Soydaner, Umut; Brenneisen, Rudolf

    2016-01-01

    Inhalation by vaporization is a promising application mode for cannabis in medicine. An in vitro validation of 5 commercial vaporizers was performed with THC-type and CBD-type cannabis. Gas chromatography/mass spectrometry was used to determine recoveries of total THC (THCtot) and total CBD (CBDtot) in the vapor. High-performance liquid chromatography with photodiode array detection was used for the quantitation of acidic cannabinoids in the residue and to calculate decarboxylation efficiencies. Recoveries of THCtot and CBDtot in the vapor of 4 electrically-driven vaporizers were 58.4 and 51.4%, 66.8 and 56.1%, 82.7 and 70.0% and 54.6 and 56.7% for Volcano Medic®, Plenty Vaporizer®, Arizer Solo® and DaVinci Vaporizer®, respectively. Decarboxylation efficiency was excellent for THC (≥ 97.3%) and CBD (≥ 94.6%). The gas-powered Vape-or-Smoke™ showed recoveries of THCtot and CBDtot in the vapor of 55.9 and 45.9%, respectively, and a decarboxylation efficiency of ≥ 87.7 for both cannabinoids. However, combustion of cannabis was observed with this device. Temperature-controlled, electrically-driven vaporizers efficiently decarboxylate inactive acidic cannabinoids and reliably release their corresponding neutral, active cannabinoids. Thus, they offer a promising application mode for the safe and efficient administration of medicinal cannabis. PMID:26784441

  20. Medicinal Cannabis: In Vitro Validation of Vaporizers for the Smoke-Free Inhalation of Cannabis

    PubMed Central

    Lanz, Christian; Mattsson, Johan; Soydaner, Umut; Brenneisen, Rudolf

    2016-01-01

    Inhalation by vaporization is a promising application mode for cannabis in medicine. An in vitro validation of 5 commercial vaporizers was performed with THC-type and CBD-type cannabis. Gas chromatography/mass spectrometry was used to determine recoveries of total THC (THCtot) and total CBD (CBDtot) in the vapor. High-performance liquid chromatography with photodiode array detection was used for the quantitation of acidic cannabinoids in the residue and to calculate decarboxylation efficiencies. Recoveries of THCtot and CBDtot in the vapor of 4 electrically-driven vaporizers were 58.4 and 51.4%, 66.8 and 56.1%, 82.7 and 70.0% and 54.6 and 56.7% for Volcano Medic®, Plenty Vaporizer®, Arizer Solo® and DaVinci Vaporizer®, respectively. Decarboxylation efficiency was excellent for THC (≥ 97.3%) and CBD (≥ 94.6%). The gas-powered Vape-or-Smoke™ showed recoveries of THCtot and CBDtot in the vapor of 55.9 and 45.9%, respectively, and a decarboxylation efficiency of ≥ 87.7 for both cannabinoids. However, combustion of cannabis was observed with this device. Temperature-controlled, electrically-driven vaporizers efficiently decarboxylate inactive acidic cannabinoids and reliably release their corresponding neutral, active cannabinoids. Thus, they offer a promising application mode for the safe and efficient administration of medicinal cannabis. PMID:26784441

  1. The nature of nitrate at the ice surface studied by XPS and NEXAFS.

    PubMed

    Krepelová, Adéla; Newberg, John; Huthwelker, Thomas; Bluhm, Hendrik; Ammann, Markus

    2010-08-21

    Trace contaminants such as strong acids have been suggested to affect the thickness of the quasi-liquid layer at the ice/air interface, which is at the heart of heterogeneous chemical reactions between snowpacks or cirrus clouds and the surrounding air. We used X-ray photoelectron spectroscopy (XPS) and electron yield near edge X-ray absorption fine structure (NEXAFS) spectroscopy at the Advanced Light Source (ALS) to probe the ice surface in the presence of HNO(3) formed from the heterogeneous hydrolysis of NO(2) at 230 K. We studied the nature of the adsorbed species at the ice/vapor interfaces as well as the effect of HNO(3) on the hydrogen bonding environment at the ice surface. The NEXAFS spectrum of ice with adsorbed HNO(3) can be represented as linear combination of the clean ice and nitrate solution spectrum, thus indicating that in the presence of HNO(3) the ice surface consists of a mixture of clean ice and nitrate ions that are coordinated as in a concentrated solution at the same temperature but higher HNO(3) pressures. PMID:20532376

  2. The nature of nitrate at the ice surface studied by XPS and NEXAFS.

    PubMed

    Krepelová, Adéla; Newberg, John; Huthwelker, Thomas; Bluhm, Hendrik; Ammann, Markus

    2010-08-21

    Trace contaminants such as strong acids have been suggested to affect the thickness of the quasi-liquid layer at the ice/air interface, which is at the heart of heterogeneous chemical reactions between snowpacks or cirrus clouds and the surrounding air. We used X-ray photoelectron spectroscopy (XPS) and electron yield near edge X-ray absorption fine structure (NEXAFS) spectroscopy at the Advanced Light Source (ALS) to probe the ice surface in the presence of HNO(3) formed from the heterogeneous hydrolysis of NO(2) at 230 K. We studied the nature of the adsorbed species at the ice/vapor interfaces as well as the effect of HNO(3) on the hydrogen bonding environment at the ice surface. The NEXAFS spectrum of ice with adsorbed HNO(3) can be represented as linear combination of the clean ice and nitrate solution spectrum, thus indicating that in the presence of HNO(3) the ice surface consists of a mixture of clean ice and nitrate ions that are coordinated as in a concentrated solution at the same temperature but higher HNO(3) pressures.

  3. Understanding Latent Heat of Vaporization.

    ERIC Educational Resources Information Center

    Linz, Ed

    1995-01-01

    Presents a simple exercise for students to do in the kitchen at home to determine the latent heat of vaporization of water using typical household materials. Designed to stress understanding by sacrificing precision for simplicity. (JRH)

  4. Portable vapor diffusion coefficient meter

    DOEpatents

    Ho, Clifford K.

    2007-06-12

    An apparatus for measuring the effective vapor diffusion coefficient of a test vapor diffusing through a sample of porous media contained within a test chamber. A chemical sensor measures the time-varying concentration of vapor that has diffused a known distance through the porous media. A data processor contained within the apparatus compares the measured sensor data with analytical predictions of the response curve based on the transient diffusion equation using Fick's Law, iterating on the choice of an effective vapor diffusion coefficient until the difference between the predicted and measured curves is minimized. Optionally, a purge fluid can forced through the porous media, permitting the apparatus to also measure a gas-phase permeability. The apparatus can be made lightweight, self-powered, and portable for use in the field.

  5. A stratospheric water vapor feedback

    NASA Astrophysics Data System (ADS)

    Dessler, A. E.; Schoeberl, M. R.; Wang, T.; Davis, S. M.; Rosenlof, K. H.

    2013-12-01

    Variations in stratospheric water vapor play a role in the evolution of our climate. We show here that variations in water vapor since 2004 can be traced to tropical tropopause layer (TTL) temperature perturbations from at least three processes: the quasi-biennial oscillation, the strength of the Brewer-Dobson circulation, and the temperature of the troposphere. The connection between stratospheric water vapor and the temperature of the troposphere implies the existence of a stratospheric water vapor feedback. We estimate the feedback in a chemistry-climate model to have a magnitude of +0.3 W/m2/K, which could be a significant contributor to the overall climate sensitivity. About two-thirds of the feedback comes from the extratropical stratosphere below ~16 km (the lowermost stratosphere), with the rest coming from the stratosphere above ~16 km (the overworld).

  6. Chemical vapor deposition sciences

    SciTech Connect

    1992-12-31

    Chemical vapor deposition (CVD) is a widely used method for depositing thin films of a variety of materials. Applications of CVD range from the fabrication of microelectronic devices to the deposition of protective coatings. New CVD processes are increasingly complex, with stringent requirements that make it more difficult to commercialize them in a timely fashion. However, a clear understanding of the fundamental science underlying a CVD process, as expressed through computer models, can substantially shorten the time required for reactor and process development. Research scientists at Sandia use a wide range of experimental and theoretical techniques for investigating the science of CVD. Experimental tools include optical probes for gas-phase and surface processes, a range of surface analytic techniques, molecular beam methods for gas/surface kinetics, flow visualization techniques and state-of-the-art crystal growth reactors. The theoretical strategy uses a structured approach to describe the coupled gas-phase and gas-surface chemistry, fluid dynamics, heat and mass transfer of a CVD process. The software used to describe chemical reaction mechanisms is easily adapted to codes that model a variety of reactor geometries. Carefully chosen experiments provide critical information on the chemical species, gas temperatures and flows that are necessary for model development and validation. This brochure provides basic information on Sandia`s capabilities in the physical and chemical sciences of CVD and related materials processing technologies. It contains a brief description of the major scientific and technical capabilities of the CVD staff and facilities, and a brief discussion of the approach that the staff uses to advance the scientific understanding of CVD processes.

  7. Vapor deposition of hardened niobium

    DOEpatents

    Blocher, Jr., John M.; Veigel, Neil D.; Landrigan, Richard B.

    1983-04-19

    A method of coating ceramic nuclear fuel particles containing a major amount of an actinide ceramic in which the particles are placed in a fluidized bed maintained at ca. 800.degree. to ca. 900.degree. C., and niobium pentachloride vapor and carbon tetrachloride vapor are led into the bed, whereby niobium metal is deposited on the particles and carbon is deposited interstitially within the niobium. Coating apparatus used in the method is also disclosed.

  8. Acidity and hydrogen exchange dynamics of iron(II)-bound nitroxyl in aqueous solution.

    PubMed

    Gao, Yin; Toubaei, Abouzar; Kong, Xianqi; Wu, Gang

    2014-10-20

    Nitroxyl-iron(II) (HNO-Fe(II)) complexes are often unstable in aqueous solution, thus making them very difficult to study. Consequently, many fundamental chemical properties of Fe(II)-bound HNO have remained unknown. Using a comprehensive multinuclear ((1)H, (15)N, (17)O) NMR approach, the acidity of the Fe(II)-bound HNO in [Fe(CN)5(HNO)](3-) was investigated and its pK(a) value was determined to be greater than 11. Additionally, HNO undergoes rapid hydrogen exchange with water in aqueous solution and this exchange process is catalyzed by both acid and base. The hydrogen exchange dynamics for the Fe(II)-bound HNO have been characterized and the obtained benchmark values, when combined with the literature data on proteins, reveal that the rate of hydrogen exchange for the Fe(II)-bound HNO in the interior of globin proteins is reduced by a factor of 10(6). PMID:25205463

  9. Finding organic vapors - a Monte Carlo approach

    NASA Astrophysics Data System (ADS)

    Vuollekoski, Henri; Boy, Michael; Kerminen, Veli-Matti; Kulmala, Markku

    2010-05-01

    Aerosols have an important role in regulating the climate both directly by absorbing and scattering solar radiation, as well as indirectly by acting as cloud condensation nuclei. While it is known that their net effect on radiative forcing is negative, several key aspects remain mysterious. There exist plenty of known primary sources of particles due to both natural and man-made origin - for example desert dust, volcanic activity and tire debris. On the other hand, it has been shown that the formation of secondary particles, by nucleation from precursor vapors, is a frequent, global phenomenon. However, the very earliest steps in new particle formation - nucleation and early growth by condensation - have many big question marks on them. While several studies have indicated the importance of a sufficient concentration of sulphuric acid vapor for the process, it has also been noted that this is usually not enough. Heads have therefore turned to organic vapors, which in their multitude could explain various observed characteristics of new particle formation. But alas, the vast number of organic compounds, their complex chemistry and properties that make them difficult to measure, have complicated the quantifying task. Nevertheless, evidence of organic contribution in particles of all size classes has been found. In particular, a significant organic constituent in the very finest particles suggests the presence of a high concentration of very low-volatile organic vapors. In this study, new particle formation in the boreal forest environment of Hyytiälä, Finland, is investigated in a process model. Our goal is to quantify the concentration, to find the diurnal profile and to get hints of the identity of some organic vapors taking part in new particle formation. Previous studies on the subject have relied on data analysis of the growth rate of the observed particles. However, due to the coarse nature of the methods used to calculate growth rates, this approach has its

  10. Use of Ni/NixB Nanoparticles as a Novel Adsorbent for the Preconcentration of Mercury Species prior to Cold Vapor-Atomic Fluorescence Spectrometric Determination.

    PubMed

    Yayayürük, Onur; Henden, Emür

    2016-01-01

    A selective matrix separation/enrichment method, utilizing a simple batch procedure with nickel/nickel boride (Ni/NixB) nanoparticles was proposed for the determination of inorganic mercury(II), Hg(2+) and methyl mercury(I), CH3Hg(+) in waters prior to cold vapor-atomic fluorescence spectrometry (CV-AFS). The Ni/NixB nanoparticles, were synthesized by the chemical reduction of Ni(II) to Ni/NixB. The novel adsorbent was selective to Hg(2+) and CH3Hg(+) species between pH values of 4 - 10. Both of the mercury species were recovered from the adsorbent using 1.0 mol L(-1) hot HNO3 with high efficiency. It was observed that the adsorbent selectively removed Hg(2+) and CH3Hg(+) from the bulk solution in the presence of several competitor ions (As(3+), Sb(3+), Pb(2+), Zn(2+), Cu(2+), Cd(2+) and Fe(3+)) with ≥96% adsorption. The limit of detection (3σ above blank) was found to be 1.8 ng L(-1) with a preconcentration factor of 20. The validation of the method was tested through spike recovery experiments with several water samples (tap and seawater) at μg L(-1) concentration levels, and all recovery values were found to vary between 95 and 105%. PMID:27506713

  11. Vapor passage fuel blockage removal

    SciTech Connect

    Faeth, W.P.

    1993-08-31

    In a method of making a system for dispensing gasoline fuel into a vehicle fuel tank, said system is described comprising a dispenser pump, a nozzle, a fuel hose connecting said dispenser pump to said nozzle for dispensing said fuel from said pump to said tank, a vapor recovery hose surrounding said fuel hose for conducting fuel vapors from the fuel tank to a storage reservoir, said fuel hose and vapor recovery hose adapted to form at least one looped low portion during dispensing of fuel into a fuel tank whereat condensed fuel vapors tend to collect in said vapor recovery passage, and a venturi means having inlet means disposed in said vapor recovery passage so as to be at said one looped low portion during said dispensing of fuel, said venturi means being so arranged that said fuel being dispensed from said pump to said tank will flow through said venturi means and create a suction at said inlet means, the improvement comprising the step of forming said inlet means to comprise a plurality of separate inlets disposed in a spaced apart relation.

  12. Corrosion investigations on zircaloy-4 and titanium dissolver materials for MOX fuel dissolution in concentrated nitric acid containing fluoride ions

    NASA Astrophysics Data System (ADS)

    Jayaraj, J.; Krishnaveni, P.; Krishna, D. Nanda Gopala; Mallika, C.; Mudali, U. Kamachi

    2016-05-01

    Aqueous reprocessing of plutonium-rich mixed oxide fuels require fluoride as a dissolution catalyst in boiling nitric acid for an effective dissolution of the spent fuel. High corrosion rates were obtained for the candidate dissolver materials zircaloy-4 (Zr-4) and commercial pure titanium (CP-Ti grade 2) in boiling 11.5 M HNO3 + 0.05 M NaF. Complexing the fluoride ions either with Al(NO3)3 or ZrO(NO3)2 aided in decreasing the corrosion rates of Zr-4 and CP-Ti. From the obtained corrosion rates it is concluded that CP-Ti is a better dissolver material than Zr-4 for extended service life in boiling 11.5 M HNO3 + 0.05 M NaF, when complexed with 0.15 M ZrO(NO3)2. XPS analysis confirmed the presence of TiO2 and absence of fluoride on the surface of CP-Ti samples, indicating that effective complexation had occurred in solution leading to passivation of the metal and imparting high corrosion resistance.

  13. A new facile route for synthesizing of graphene oxide using mixture of sulfuric-nitric-phosphoric acids as intercalating agent

    NASA Astrophysics Data System (ADS)

    Panwar, Vinay; Chattree, Ananya; Pal, Kaushik

    2015-09-01

    In this work, graphene oxide (GO) has been prepared through three different processes namely, eco-friendly Hummers method, modification in improved Hummers method and a new approach. This new approach has been designed by changing some processing parameters and intercalating agent for significant reduction in processing time and to improve the quantity of GO in comparison to the other two methods. This has been achieved through better oxidization of graphite using nitric-sulfuric acid (HNO3-H2SO4) as intercalating agent. X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, Atomic Force Microscopy (AFM), X-ray photoelectron spectroscopy (XPS), UV-visible spectroscopy, and Thermogravimetric analysis (TGA) are used to characterize the GO prepared through different processes. These characterizations have confirmed an improved exfoliation of graphite, using addition of HNO3 in intercalating agent, in a short processing time and bring on higher yield of GO via this new process.

  14. Review of heterogeneous photochemical reactions of NOy on aerosol - A possible daytime source of nitrous acid (HONO) in the atmosphere.

    PubMed

    Ma, Jinzhu; Liu, Yongchun; Han, Chong; Ma, Qingxin; Liu, Chang; He, Hong

    2013-02-01

    As an important precursor of hydroxyl radical, nitrous acid (HONO) plays a key role in the chemistry of the lower atmosphere. Recent atmospheric measurements and model calculations show strong enhancement for HONO formation during daytime, while they are inconsistent with the known sources in the atmosphere, suggesting that current models are lacking important sources for HONO. In this article, heterogeneous photochemical reactions of nitric acid/nitrate anion and nitrogen oxide on various aerosols were reviewed and their potential contribution to HONO formation was also discussed. It is demonstrated that HONO can be formed by photochemical reaction on surfaces with deposited HNO3, by photocatalytic reaction of NO2 on TiO2 or TiO2-containing materials, and by photochemical reaction of NO2 on soot, humic acids or other photosensitized organic surfaces. Although significant uncertainties still exist in the exact mechanisms and the yield of HONO, these additional sources might explain daytime observations in the atmosphere.

  15. Dissociation of nitric acid at an aqueous surface: Large amplitude motions in the contact ion pair to solvent-separated ion pair conversion.

    PubMed

    Wang, Shuzhi; Bianco, Roberto; Hynes, James T

    2010-08-01

    Beyond its fundamental interest, the acid dissociation of nitric acid (HNO(3)) at an aqueous interface is of importance in a wide variety of atmospheric contexts. Here we present a Car-Parrinello molecular dynamics (CPMD) study of the second step of this process, the formation, via proton transfer (PT), of a solvent-separated ion pair (SSIP) from a contact ion pair (CIP) of the hydronium (H(3)O(+)) and the nitrate (NO) ions. This reaction represents an extension of our earlier CPMD study of the first PT step to produce the CIP from molecular HNO(3) at various locations at and below the aqueous surface (S. Wang, R. Bianco and J. T. Hynes, J. Phys. Chem. A, 2009, 113, 1295); it is important in establishing the ionic distribution in the aqueous interfacial region, with potential consequences for heterogeneous reactions occurring in that region. We focus on the large amplitude, microscopic level motions-such as the hydrogen-bonding coordination number changes around the proton-donating and -accepting species-which are key for the CIP --> SSIP PT conversion. PMID:20498901

  16. 21 CFR 868.5880 - Anesthetic vaporizer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Anesthetic vaporizer. 868.5880 Section 868.5880...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5880 Anesthetic vaporizer. (a) Identification. An anesthetic vaporizer is a device used to vaporize liquid anesthetic and deliver a...

  17. 21 CFR 868.5880 - Anesthetic vaporizer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Anesthetic vaporizer. 868.5880 Section 868.5880...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5880 Anesthetic vaporizer. (a) Identification. An anesthetic vaporizer is a device used to vaporize liquid anesthetic and deliver a...

  18. 21 CFR 868.5880 - Anesthetic vaporizer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Anesthetic vaporizer. 868.5880 Section 868.5880...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5880 Anesthetic vaporizer. (a) Identification. An anesthetic vaporizer is a device used to vaporize liquid anesthetic and deliver a...

  19. 21 CFR 868.5880 - Anesthetic vaporizer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Anesthetic vaporizer. 868.5880 Section 868.5880...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5880 Anesthetic vaporizer. (a) Identification. An anesthetic vaporizer is a device used to vaporize liquid anesthetic and deliver a...

  20. 21 CFR 868.5880 - Anesthetic vaporizer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Anesthetic vaporizer. 868.5880 Section 868.5880...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5880 Anesthetic vaporizer. (a) Identification. An anesthetic vaporizer is a device used to vaporize liquid anesthetic and deliver a...

  1. Dispensing fuel with aspiration of condensed vapors

    SciTech Connect

    Butkovich, M.S.; Strock, D.J.

    1993-08-10

    A vapor recovery process is described, comprising the steps of: fueling a motor vehicle with gasoline by discharging gasoline into a fill opening or filler pipe of a tank of said vehicle through a fuel outlet conduit of a nozzle; emitting gasoline vapors from said tank during said fueling; substantially collecting said vapors during said fueling with a vapor return conduit of said nozzle and passing said vapors through said vapor return conduit in counter current flow relationship to said discharging gasoline in said fuel conduit; conveying said vapors from said vapor return conduit to a vapor return hose; at least some of said vapors condensing to form condensate in said vapor return hose; substantially removing said condensate from said vapor return hose during said fueling with a condensate pickup tube from said nozzle by passing said condensate through said condensate pickup tube in counter current flow relationship to said conveying vapors in said vapor return hose; sensing the presence of gasoline with a liquid sensing tube in said vapor return conduit of said nozzle between inner and outer spouts of said nozzle to detect when said tank of said vehicle is filled with said fuel conduit being within the inner spout of said nozzle; and automatically shutting off said fueling and condensate removing when said liquid sensing tube detects when said tank of said vehicle is filled and fuel enters said vapor return conduit.

  2. The Lithium Vapor Box Divertor

    NASA Astrophysics Data System (ADS)

    Goldston, Robert; Hakim, Ammar; Hammett, Gregory; Jaworski, Michael; Myers, Rachel; Schwartz, Jacob

    2015-11-01

    Projections of scrape-off layer width to a demonstration power plant suggest an immense parallel heat flux, of order 12 GW/m2, which will necessitate nearly fully detached operation. Building on earlier work by Nagayama et al. and by Ono et al., we propose to use a series of differentially pumped boxes filled with lithium vapor to isolate the buffering vapor from the main plasma chamber, allowing stable detachment. This powerful differential pumping is only available for condensable vapors, not conventional gases. We demonstrate the properties of such a system through conservation laws for vapor mass and enthalpy, and then include plasma entrainment and ultimately an estimate of radiated power. We find that full detachment should be achievable with little leakage of lithium to the main plasma chamber. We also present progress towards solving the Navier-Stokes equation numerically for the chain of vapor boxes, including self-consistent wall boundary conditions and fully-developed shocks, as well as concepts for an initial experimental demonstration-of-concept. This work supported by DOE Contract No. DE-AC02-09CH11466.

  3. Summer-time distribution of air pollutants in Sequoia National Park, California.

    PubMed

    Bytnerowicz, Andrzej; Tausz, Michael; Alonso, Rocio; Jones, David; Johnson, Ronald; Grulke, Nancy

    2002-01-01

    Concentrations of air pollutants were monitored during the May November 1999 period on a network of forested sites in Sequoia National Park, California. Measurements were conducted with: (1) active monitors for nitric oxide (NO), nitrogen dioxide (NO2) and ozone (O3); (2) honeycomb denuder/filter pack systems for nitric acid vapor (HNO3), nitrous acid vapor (HNO2), ammonia (NH3), sulfur dioxide (SO2), particulate nitrate (NO3-), ammonium (NH4+), and sulfate (SO4(2-)); and (3) passive samplers for O3, HNO3 and NO2. Elevated concentrations of O3 (seasonal means 41-71 ppb), HNO3 (seasonal means 0.4-2.9 microg/m3), NH3 (seasonal means 1.6-4.5 microg/m3), NO3 (1.1-2.0 microg/m3) and NH4+ (1.0-1.9 microg/m3) were determined. Concentrations of other pollutants were low. With increasing elevation and distance from the pollution source area of O3, NH3 and HNO3 concentrations decreased. Ammonia and NH4+ were dominant N pollutants indicating strong influence of agricultural emissions on forests and other ecosystems of the Sequoia National Park. PMID:11939282

  4. A-train CALIOP and MLS observations of early winter antarctic polar stratospheric clouds and nitric acid in 2008

    NASA Astrophysics Data System (ADS)

    Lambert, A.; Santee, M. L.; Wu, D. L.; Chae, J. H.

    2011-10-01

    A-train Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Microwave Limb Sounder (MLS) observations are used to investigate the development of polar stratospheric clouds (PSCs) and the gas phase nitric acid distribution in the early 2008 Antarctic winter. Observational evidence of gravity-wave activity is provided by Atmospheric Infrared Sounder (AIRS) radiances and infrared spectroscopic detection of nitric acid trihydrate (NAT) in PSCs is obtained from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Goddard Earth Observing System Data Assimilation System (GEOS-5 DAS) analyses are used to derive Lagrangian trajectories and to determine temperature-time histories of air parcels. We use CALIOP backscatter and depolarization measurements to classify PSCs and the MLS measurements to determine the corresponding gas phase HNO3 as a function of temperature. For liquid PSCs the uptake of HNO3 follows the theoretical equilibrium curve for supercooled ternary solutions (STS), but at temperatures about 1 K lower as determined from GEOS-5. In the presence of solid phase PSCs, above the ice frost-point, the HNO3 depletion occurs over a wider range of temperatures (+2 to -7 K) distributed about the NAT equilibrium curve. Rapid gas phase HNO3 depletion is first seen by MLS from from 23-25 May 2008, consisting of a decrease in the volume mixing ratio (parts per billion by volume) from 14 ppbv to 7 ppbv on the 46-32 hPa (hectopascal) pressure levels and accompanied by a 2-3 ppbv increase by renitrification at the 68 hPa pressure level. Temperature-time histories of air parcels demonstrate that the depleted HNO3 region is more clearly correlated with prior low temperature exposure of a few kelvin above the frost-point than with either the region bounded by the NAT existence temperature threshold or the region of minimum temperatures. From the combined data we infer the presence of large-size NAT particles with effective radii >5-7 μm and low NAT

  5. A-train CALIOP and MLS observations of early winter Antarctic polar stratospheric clouds and nitric acid in 2008

    NASA Astrophysics Data System (ADS)

    Lambert, A.; Santee, M. L.; Wu, D. L.; Chae, J. H.

    2012-03-01

    A-train Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Microwave Limb Sounder (MLS) observations are used to investigate the development of polar stratospheric clouds (PSCs) and the gas-phase nitric acid distribution in the early 2008 Antarctic winter. Observational evidence of gravity-wave activity is provided by Atmospheric Infrared Sounder (AIRS) radiances and infrared spectroscopic detection of nitric acid trihydrate (NAT) in PSCs is obtained from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Goddard Earth Observing System Data Assimilation System (GEOS-5 DAS) analyses are used to derive Lagrangian trajectories and to determine temperature-time histories of air parcels. We use CALIOP backscatter and depolarization measurements to classify PSCs and the MLS measurements to determine the corresponding gas-phase HNO3 as a function of temperature. For liquid PSCs the uptake of HNO3 follows the theoretical equilibrium curve for supercooled ternary solutions (STS), but at temperatures about 1 K lower as determined from GEOS-5. In the presence of solid phase PSCs, above the ice frost-point, the HNO3 depletion occurs over a wider range of temperatures (+2 to -7 K) distributed about the NAT equilibrium curve. Rapid gas-phase HNO3 depletion is first seen by MLS from from 23-25 May 2008, consisting of a decrease in the volume mixing ratio from 14 ppbv (parts per billion by volume) to 7 ppbv on the 46-32 hPa (hectopascal) pressure levels and accompanied by a 2-3 ppbv increase by renitrification at the 68 hPa pressure level. The observed region of depleted HNO3 is substantially smaller than the region bounded by the NAT existence temperature threshold. Temperature-time histories of air parcels demonstrate that the depletion is more clearly correlated with prior exposure to temperatures a few kelvin above the frost-point. From the combined data we infer the presence of large-size NAT particles with effective radii >5-7 μm and low NAT

  6. Electrical Breakdown in Water Vapor

    SciTech Connect

    Skoro, N.; Maric, D.; Malovic, G.; Petrovic, Z. Lj.; Graham, W. G.

    2011-11-15

    In this paper investigations of the voltage required to break down water vapor are reported for the region around the Paschen minimum and to the left of it. In spite of numerous applications of discharges in biomedicine, and recent studies of discharges in water and vapor bubbles and discharges with liquid water electrodes, studies of the basic parameters of breakdown are lacking. Paschen curves have been measured by recording voltages and currents in the low-current Townsend regime and extrapolating them to zero current. The minimum electrical breakdown voltage for water vapor was found to be 480 V at a pressure times electrode distance (pd) value of around 0.6 Torr cm ({approx}0.8 Pa m). The present measurements are also interpreted using (and add additional insight into) the developing understanding of relevant atomic and particularly surface processes associated with electrical breakdown.

  7. Marine loading vapor control systems

    SciTech Connect

    Babet, F.H.

    1996-09-01

    The EPA and State air quality control boards have mandated the collection and destruction or recovery of vapors generated by the loading of some hydrocarbons and chemicals into marine vessels. This is a brief overview of the main US Coast Guard requirements for marine vapor control systems. As with most regulations, they are open to interpretation. In an attempt to more clearly define the intent of the regulations, the US Coast Guard has issued guidelines to assist the certifying entities in ensuring compliance with intended regulations. If a company is contemplating the installation of a marine loading vapor control system, the authors strongly recommend that one engage the services of a certifying entity, either as the designer, or an advisor and ultimately the certifier of the system. This should be done well up front in the design of the system to avoid costly mistakes which can occur as a result of lack of knowledge or misinterpretation of the regulations and guidelines.

  8. Potentiometric detection of chemical vapors using molecularly imprinted polymers as receptors

    NASA Astrophysics Data System (ADS)

    Liang, Rongning; Chen, Lusi; Qin, Wei

    2015-07-01

    Ion-selective electrode (ISE) based potentiometric gas sensors have shown to be promising analytical tools for detection of chemical vapors. However, such sensors are only capable of detecting those vapors which can be converted into ionic species in solution. This paper describes for the first time a polymer membrane ISE based potentiometric sensing system for sensitive and selective determination of neutral vapors in the gas phase. A molecularly imprinted polymer (MIP) is incorporated into the ISE membrane and used as the receptor for selective adsorption of the analyte vapor from the gas phase into the sensing membrane phase. An indicator ion with a structure similar to that of the vapor molecule is employed to indicate the change in the MIP binding sites in the membrane induced by the molecular recognition of the vapor. The toluene vapor is used as a model and benzoic acid is chosen as its indicator. Coupled to an apparatus manifold for preparation of vapor samples, the proposed ISE can be utilized to determine volatile toluene in the gas phase and allows potentiometric detection down to parts per million levels. This work demonstrates the possibility of developing a general sensing principle for detection of neutral vapors using ISEs.

  9. Potentiometric detection of chemical vapors using molecularly imprinted polymers as receptors

    PubMed Central

    Liang, Rongning; Chen, Lusi; Qin, Wei

    2015-01-01

    Ion-selective electrode (ISE) based potentiometric gas sensors have shown to be promising analytical tools for detection of chemical vapors. However, such sensors are only capable of detecting those vapors which can be converted into ionic species in solution. This paper describes for the first time a polymer membrane ISE based potentiometric sensing system for sensitive and selective determination of neutral vapors in the gas phase. A molecularly imprinted polymer (MIP) is incorporated into the ISE membrane and used as the receptor for selective adsorption of the analyte vapor from the gas phase into the sensing membrane phase. An indicator ion with a structure similar to that of the vapor molecule is employed to indicate the change in the MIP binding sites in the membrane induced by the molecular recognition of the vapor. The toluene vapor is used as a model and benzoic acid is chosen as its indicator. Coupled to an apparatus manifold for preparation of vapor samples, the proposed ISE can be utilized to determine volatile toluene in the gas phase and allows potentiometric detection down to parts per million levels. This work demonstrates the possibility of developing a general sensing principle for detection of neutral vapors using ISEs. PMID:26215887

  10. Vapor deposition of thin films

    DOEpatents

    Smith, David C.; Pattillo, Stevan G.; Laia, Jr., Joseph R.; Sattelberger, Alfred P.

    1992-01-01

    A highly pure thin metal film having a nanocrystalline structure and a process of preparing such highly pure thin metal films of, e.g., rhodium, iridium, molybdenum, tungsten, rhenium, platinum, or palladium by plasma assisted chemical vapor deposition of, e.g., rhodium(allyl).sub.3, iridium(allyl).sub.3, molybdenum(allyl).sub.4, tungsten(allyl).sub.4, rhenium(allyl).sub.4, platinum(allyl).sub.2, or palladium(allyl).sub.2 are disclosed. Additionally, a general process of reducing the carbon content of a metallic film prepared from one or more organometallic precursor compounds by plasma assisted chemical vapor deposition is disclosed.

  11. Nitric Acid Uptake on Subtropical Cirrus Cloud Particles

    NASA Technical Reports Server (NTRS)

    Popp, P. J.; Gao, R. S.; Marcy, T. P.; Fahey, D. W.; Hudson, P. K.; Thompson, T. L.; Kaercher, B.; Ridley, B. A.; Weinheimer, A. J.; Knapp, D. J.; Montzka, D. D.; Baumgardner, D.; Garrett, T. J.; Weinstock, E. M.; Smith, J. B.; Sayres, D. S.; Pittman, J. V.; Dhaniyala, S.; Bui, T. P.; Mahoney, M. J.

    2004-01-01

    The redistribution of HNO3 via uptake and sedimentation by cirrus cloud particles is considered an important term in the upper tropospheric budget of reactive nitrogen. Numerous cirrus cloud encounters by the NASA WB-57F high-altitude research aircraft during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) were accompanied by the observation of condensed-phase HNO3 with the NOAA chemical ionization mass spectrometer. The instrument measures HNO3 with two independent channels of detection connected to separate forward and downward facing inlets that allow a determination of the amount of HNO3 condensed on ice particles. Subtropical cirrus clouds, as indicated by the presence of ice particles, were observed coincident with condensed-phase HNO3 at temperatures of 197-224 K and pressures of 122-224 hPa. Maximum levels of condensed-phase HNO3 approached the gas-phase equivalent of 0.8 ppbv. Ice particle surface coverages as high as 1.4 # 10(exp 14) molecules/ square cm were observed. A dissociative Langmuir adsorption model, when using an empirically derived HNO3 adsorption enthalpy of -11.0 kcal/mol, effectively describes the observed molecular coverages to within a factor of 5. The percentage of total HNO3 in the condensed phase ranged from near zero to 100% in the observed cirrus clouds. With volume-weighted mean particle diameters up to 700 ?m and particle fall velocities up to 10 m/s, some observed clouds have significant potential to redistribute HNO3 in the upper troposphere.

  12. Nitric Acid Uptake on Subtropical Cirrus Cloud Particles

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The redistribution of HNO3 via uptake and sedimentation by cirrus cloud particles is considered an important term in the upper tropospheric budget of reactive nitrogen. Numerous cirrus cloud encounters by the NASA WB-57F high-altitude research aircraft during CRYSTAL-FACE were accompanied by the observation of condensed-phase HNO3 with the NOAA chemical ionization mass spectrometer. The instrument measures HNO3 with two independent channels of detection connected to separate forward- and downward-facing inlets that allow a determination of the amount of HNO3 condensed on ice particles. Subtropical cirrus clouds, as indicated by the presence of ice particles, were observed coincident with condensed-phase HNO3 at temperatures of 197 K - 224 K and pressures of 122 hPa - 224 hPa. Maximum levels of condensed-phase HNO3 approached the gas-phase equivalent of 0.8 ppbv. Ice particle surface coverages as high as 1.4- 10(exp 14) molecules/sq cm were observed. A dissociative Langmuir adsorption model, when using an empirically derived HNO3 adsorption enthalpy of -11.0 kcal/mol, effectively describes the observed molecular coverages to within a factor of 5. The percentage of total HNO3 in the condensed phase ranged from near zero to 100% in the observed cirrus clouds. With volume-weighted mean particle diameters up to 700 pm and particle fall velocities up to 10 m/s, some observed clouds have significant potential to redistribute HNO3 in the upper troposphere.

  13. Transition metal cation separations with a resorcinarene-based amino acid stationary phase.

    PubMed

    Li, Na; Allen, Lee J; Harrison, Roger G; Lamb, John D

    2013-03-01

    A resorcinarene-based macrocyclic ligand functionalized with alanine and undecyl groups (AUA) was synthesized and applied to ion chromatographic separations. The selectivity and separation of transition metal ions on a column packed with AUA adsorbed onto 55% cross-linked styrene-divinylbenzene resin are presented. The upper and lower rims of the resorcinarene were modified with amino acids and -C(11)H(23) alkyl chains, respectively. The four carboxylic acid groups on the upper rim act as cation-exchangers while the four -C(11)H(23) alkyl chains serve to anchor the ligand to the resin surface by the hydrophobic effect. A systematic study of the effect of different eluent components including non-metal-chelating (HNO(3)) and chelating acids (oxalic acid, succinic acid, dipicolinic acid, and citric acid) on the retention of transition metal ions was investigated. Six metal ions (Mn(2+), Co(2+), Ni(2+), Cd(2+), Cu(2+), and Zn(2+)) were separated on the AUA column within a reasonable time with a single eluent gradient using oxalic acid. The separation is compared to that obtained using a commercial column containing carboxylic acid functional groups. The AUA column containing four preorganized carboxylic acid groups showed selectivity for Cu(2+) when no chelating eluent was present, a selectivity which was not observed with the comparison column.

  14. Low level vapor verification of monomethyl hydrazine

    NASA Technical Reports Server (NTRS)

    Mehta, Narinder

    1990-01-01

    The vapor scrubbing system and the coulometric test procedure for the low level vapor verification of monomethyl hydrazine (MMH) are evaluated. Experimental data on precision, efficiency of the scrubbing liquid, instrument response, detection and reliable quantitation limits, stability of the vapor scrubbed solution, and interference were obtained to assess the applicability of the method for the low ppb level detection of the analyte vapor in air. The results indicated that the analyte vapor scrubbing system and the coulometric test procedure can be utilized for the quantitative detection of low ppb level vapor of MMH in air.

  15. Catalytic Ethanol Dehydration over Different Acid-activated Montmorillonite Clays.

    PubMed

    Krutpijit, Chadaporn; Jongsomjit, Bunjerd

    2016-01-01

    In the present study, the catalytic dehydration of ethanol to obtain ethylene over montmorillonite clays (MMT) with mineral acid activation including H2SO4 (SA-MMT), HCl (HA-MMT) and HNO3 (NA-MMT) was investigated at temperature range of 200 to 400°C. It revealed that HA-MMT exhibited the highest catalytic activity. Ethanol conversion and ethylene selectivity were found to increase with increased reaction temperature. At 400°C, the HA-MMT yielded 82% of ethanol conversion having 78% of ethylene yield. At lower temperature (i.e. 200 to 300°C), diethyl ether (DEE) was a major product. The highest activity obtained from HA-MMT can be attributed to an increase of weak acid sites and acid density by the activation of MMT with HCl. It can be also proven by various characterization techniques that in most case, the main structure of MMT did not alter by acid activation (excepted for NA-MMT). Upon the stability test for 72 h during the reaction, the MMT and HA-MMT showed only slight deactivation due to carbon deposition. Hence, the acid activation of MMT by HCl is promising to enhance the catalytic dehydration of ethanol. PMID:27041515

  16. The effects of acid leaching on 40Ar/39Ar age dating results using samples from the Walvis Ridge hotspot trail

    NASA Astrophysics Data System (ADS)

    Klath, J. F.; Koppers, A. A.; Heaton, D. E.; Schnur, S.

    2013-12-01

    In this study we systematically explore how acid leaching can be used to reduce the negative effects of seawater alteration on the 40Ar/39Ar age dating of submarine basalts. Koppers et al (2000) showed that acid leaching of groundmass samples generated more consistent ages as well as ages more concordant with phenocrystic mineral phases, compared to samples that were left untreated. By studying the effects of progressively increasing the strength and length of acid treatment, we will show how acid leaching of groundmass separates reduces alteration while leaving the initial eruption signature intact. Samples were chosen from the Walvis ridge hotspot trail in the southeast Atlantic. Three samples were selected based on degree and style of alteration. Two samples (basalt and basaltic andesite) appear highly altered in thin section. The basalt contains diffuse iddingsite alteration that is pervasive throughout the groundmass. The basaltic andesite displays focused secondary mineral phases within and around abundant vesicles. The third sample, a trachyte, shows relatively minor degrees of alteration in thin section. These groundmass separates were divided into four splits and treated with a progressively stronger acid and for longer duration. One split from each rock was left untreated to act as a baseline. Of the other three splits from each sample, one was treated with a mild leach (1N HCl and 1N HNO3), one a strong leach (1N HCl, 1N HNO3, 6N HCl, and 3N HNO3), and lastly the strong leach performed twice. The samples were then handpicked to remove any remaining visible alteration. The untreated samples were picked as well, removing the most distinctly altered grains. All splits were analyzed by electron microprobe, x-ray fluorescence (XRF) and the incremental heating 40Ar/39Ar dating method. We will report on the results of an image analysis of microprobe backscatter images and elemental maps taken of individual groundmass grains. This analysis will show the location

  17. Measurements of Acidic Gases and Aerosol Species Aboard the NASA DC-8 Aircraft During the Pacific Exploratory Mission in the Tropics (PEM-Tropics A)

    NASA Technical Reports Server (NTRS)

    Talbot, Robert W.; Dibb, Jack E.

    1999-01-01

    We received funding to provide measurements of nitric acid (HNO3), formic acid (HCOOH), acetic acid (CH3COOH), and the chemical composition of aerosols aboard the NASA Ames DC-8 research aircraft during the PEM-Tropics A mission. These measurements were successfully completed and the final data resides in the electronic archive (ftp-gte.larc.nasa.gov) at NASA Langley Research Center. For the PEM-Tropics A mission the University of New Hampshire group was first author of four different manuscripts. Three of these have now appeared in the Journal of Geophysical Research-Atmospheres, included in the two section sections on PEM-Tropics A. The fourth manuscript has just recently been submitted to this same journal as a stand alone paper. All four of these papers are included in this report. The first paper (Influence of biomass combustion emissions on the distribution of acidic trace gases over the Southern Pacific basin during austral springtime) describes the large-scale distributions of HNO3, HCOOH, and CH3COOH. Arguments were presented to show, particularly in the middle tropospheric region, that biomass burning emissions from South America and Africa were a major source of acidic gases over the South Pacific basin. The second paper (Aerosol chemical composition and distribution during the Pacific Exploratory Mission (PEM) Tropics) covers the aerosol aspects of our measurement package. Compared to acidic gases, O3, and selected hydrocarbons, the aerosol chemistry showed little influence from biomass burning emissions. The data collected in the marine boundary layer showed a possible marine source of NH3 to the troposphere in equatorial areas. This source had been speculated on previously, but our data was the first collected from an airborne platform to show its large-scale features. The third paper (Constraints on the age and dilution of Pacific Exploratory Mission-Tropics biomass burning plumes from the natural radionuclide tracer Pb-210) utilized the unexpectedly

  18. Effects of inorganic acids and divalent hydrated metal cations (Mg(2+), Ca(2+), Co(2+), Ni(2+)) on γ-AlOOH sol-gel process.

    PubMed

    Zhang, Jian; Xia, Yuguo; Zhang, Li; Chen, Dairong; Jiao, Xiuling

    2015-11-01

    In-depth understanding of the sol-gel process plays an essential role in guiding the preparation of new materials. Herein, the effects of different inorganic acids (HCl, HNO3 and H2SO4) and divalent hydrated metal cations (Mg(2+), Ca(2+), Co(2+), Ni(2+)) on γ-AlOOH sol-gel process were studied based on experiments and density functional theory (DFT) calculations. In these experiments, the sol originating from the γ-AlOOH suspension was formed only with the addition of HCl and HNO3, but not with H2SO4. Furthermore, the DFT calculations showed that the strong adsorption of HSO4(-) on the surface of the γ-AlOOH particles, and the hydrogen in HSO4(-) pointing towards the solvent lead to an unstable configuration of electric double layer (EDL). In the experiment, the gelation time sequence of γ-AlOOH sol obtained by adding metal ions changed when the ionic strength was equal to or greater than 0.198 mol kg(-1). The DFT calculations demonstrated that the adsorption energy of hydrated metal ions on the γ-AlOOH surface can actually make a difference in the sol-gel process.

  19. Impact of stratospheric aircraft on calculations of nitric acid trihydrate cloud surface area densities using NMC temperatures and 2D model constituent distributions

    NASA Technical Reports Server (NTRS)

    Considine, David B.; Douglass, Anne R.

    1994-01-01

    A parameterization of NAT (nitric acid trihydrate) clouds is developed for use in 2D models of the stratosphere. The parameterization uses model distributions of HNO3 and H2O to determine critical temperatures for NAT formation as a function of latitude and pressure. National Meteorological Center temperature fields are then used to determine monthly temperature frequency distributions, also as a function of latitude and pressure. The fractions of these distributions which fall below the critical temperatures for NAT formation are then used to determine the NAT cloud surface area density for each location in the model grid. By specifying heterogeneous reaction rates as functions of the surface area density, it is then possible to assess the effects of the NAT clouds on model constituent distributions. We also consider the increase in the NAT cloud formation in the presence of a fleet of stratospheric aircraft. The stratospheric aircraft NO(x) and H2O perturbations result in increased HNO3 as well as H2O. This increases the probability of NAT formation substantially, especially if it is assumed that the aircraft perturbations are confined to a corridor region.

  20. Vapor generation methods for explosives detection research

    SciTech Connect

    Grate, Jay W.; Ewing, Robert G.; Atkinson, David A.

    2012-12-01

    The generation of calibrated vapor samples of explosives compounds remains a challenge due to the low vapor pressures of the explosives, adsorption of explosives on container and tubing walls, and the requirement to manage (typically) multiple temperature zones as the vapor is generated, diluted, and delivered. Methods that have been described to generate vapors can be classified as continuous or pulsed flow vapor generators. Vapor sources for continuous flow generators are typically explosives compounds supported on a solid support, or compounds contained in a permeation or diffusion device. Sources are held at elevated isothermal temperatures. Similar sources can be used for pulsed vapor generators; however, pulsed systems may also use injection of solutions onto heated surfaces with generation of both solvent and explosives vapors, transient peaks from a gas chromatograph, or vapors generated by s programmed thermal desorption. This article reviews vapor generator approaches with emphasis on the method of generating the vapors and on practical aspects of vapor dilution and handling. In addition, a gas chromatographic system with two ovens that is configurable with up to four heating ropes is proposed that could serve as a single integrated platform for explosives vapor generation and device testing. Issues related to standards, calibration, and safety are also discussed.

  1. Method and apparatus for vapor detection

    NASA Technical Reports Server (NTRS)

    Lerner, Melvin (Inventor); Hood, Lyal V. (Inventor); Rommel, Marjorie A. (Inventor); Pettitt, Bruce C. (Inventor); Erikson, Charles M. (Inventor)

    1980-01-01

    The method disclosed herein may be practiced by passing the vapors to be sampled along a path with halogen vapor, preferably chlorine vapor, heating the mixed vapors to halogenate those of the sampled vapors subject to halogenation, removing unreacted halogen vapor, and then sensing the vapors for organic halogenated compounds. The apparatus disclosed herein comprises means for flowing the vapors, both sample and halogen vapors, into a common path, means for heating the mixed vapors to effect the halogenation reaction, means for removing unreacted halogen vapor, and a sensing device for sensing halogenated compounds. By such a method and means, the vapors of low molecular weight hydrocarbons, ketones and alcohols, when present, such as methane, ethane, acetone, ethanol, and the like are converted, at least in part, to halogenated compounds, then the excess halogen removed or trapped, and the resultant vapors of the halogenated compounds sensed or detected. The system is highly sensitive. For example, acetone in a concentration of 30 parts per billion (volume) is readily detected.

  2. Hydrazine vapor inactivates Bacillus spores

    NASA Astrophysics Data System (ADS)

    Schubert, Wayne W.; Engler, Diane L.; Beaudet, Robert A.

    2016-05-01

    NASA policy restricts the total number of bacterial spores that can remain on a spacecraft traveling to any planetary body which might harbor life or have evidence of past life. Hydrazine, N2H4, is commonly used as a propellant on spacecraft. Hydrazine as a liquid is known to inactivate bacterial spores. We have now verified that hydrazine vapor also inactivates bacterial spores. After Bacillus atrophaeus ATCC 9372 spores deposited on stainless steel coupons were exposed to saturated hydrazine vapor in closed containers, the spores were recovered from the coupons, serially diluted, pour plated and the surviving bacterial colonies were counted. The exposure times required to reduce the spore population by a factor of ten, known as the D-value, were 4.70 ± 0.50 h at 25 °C and 2.85 ± 0.13 h at 35 °C. These inactivation rates are short enough to ensure that the bioburden of the surfaces and volumes would be negligible after prolonged exposure to hydrazine vapor. Thus, all the propellant tubing and internal tank surfaces exposed to hydrazine vapor do not contribute to the total spore count.

  3. Simple Chemical Vapor Deposition Experiment

    ERIC Educational Resources Information Center

    Pedersen, Henrik

    2014-01-01

    Chemical vapor deposition (CVD) is a process commonly used for the synthesis of thin films for several important technological applications, for example, microelectronics, hard coatings, and smart windows. Unfortunately, the complexity and prohibitive cost of CVD equipment makes it seldom available for undergraduate chemistry students. Here, a…

  4. Acoustic Behavior of Vapor Bubbles

    NASA Technical Reports Server (NTRS)

    Prosperetti, Andrea; Oguz, Hasan N.

    1996-01-01

    In a microgravity environment vapor bubbles generated at a boiling surface tend to remain near it for a long time. This affects the boiling heat transfer and in particular promotes an early transition to the highly inefficient film boiling regime. This paper describes the physical basis underlying attempts to remove the bubbles by means of pressure radiation forces.

  5. Vacuum vapor deposition gun assembly

    DOEpatents

    Zeren, Joseph D.

    1985-01-01

    A vapor deposition gun assembly includes a hollow body having a cylindrical outer surface and an end plate for holding an adjustable heat sink, a hot hollow cathode gun, two magnets for steering the plasma from the gun into a crucible on the heat sink, and a shutter for selectively covering and uncovering the crucible.

  6. Effects of combinations of simulated acid rain and cadmium or zinc on microbial activity in soil.

    PubMed

    Bewley, R J; Stotzky, G

    1983-08-01

    There was little effect on the rate of CO2 evolution from glucose-supplemented soil, adjusted to pH 3.2 with a 2:1 combination of H2SO4 and fuming HNO3, and concomitant additions of 100 or 1000 ppm Cd or of 1000 or 10,000 ppm Zn (as sulfates) were no more inhibitory than in soil untreated with acid. In soil adjusted to pH 2.8, the lag in CO2 evolution was increased by 1 day, and was extended further by the concomitant addition of 10,000 but not 1000 ppm Zn or of 1000 but not 100 ppm Cd. The growth of Aspergillus niger in soil acidified to pH levels of 3.6 to 4.2 was further reduced by the addition of either 100 or 250 ppm Cd or of 1000 ppm Zn.

  7. Evaluation of ionic pollutants of acid fog and rain using a factor analysis and back trajectories.

    PubMed

    Adzuhata, T; Inotsume, J; Okamura, T; Kikuchi, R; Ozeki, T; Kajikawa, M; Ogawa, N

    2001-01-01

    Fog and rain water samples were collected at the same time in the Akita Hachimantai mountain range in northern Japan from June to September in 1998 and 1999. The various ion concentrations in these samples were analyzed, and the fog droplet sizes were measured for each fog event. As the fog droplet size increased, the ion concentration decreased. The slope of log-log plots of the concentration versus the droplet size differed with the kind of ion. In order to characterize the air pollutant, moreover, these data were quantitatively analyzed by an oblique rotational factor analysis. We found that three factors were extracted as the air pollutant source: (NH4)2SO4, acids (HNO3 + H2SO4) and sea-salt. Combining the factor analysis with the 72 h back-trajectory at 850 hPa level, we found that the contribution of each factor varied with the transport pattern of air masses.

  8. Evaluation of ionic pollutants of acid fog and rain using a factor analysis and back trajectories.

    PubMed

    Adzuhata, T; Inotsume, J; Okamura, T; Kikuchi, R; Ozeki, T; Kajikawa, M; Ogawa, N

    2001-01-01

    Fog and rain water samples were collected at the same time in the Akita Hachimantai mountain range in northern Japan from June to September in 1998 and 1999. The various ion concentrations in these samples were analyzed, and the fog droplet sizes were measured for each fog event. As the fog droplet size increased, the ion concentration decreased. The slope of log-log plots of the concentration versus the droplet size differed with the kind of ion. In order to characterize the air pollutant, moreover, these data were quantitatively analyzed by an oblique rotational factor analysis. We found that three factors were extracted as the air pollutant source: (NH4)2SO4, acids (HNO3 + H2SO4) and sea-salt. Combining the factor analysis with the 72 h back-trajectory at 850 hPa level, we found that the contribution of each factor varied with the transport pattern of air masses. PMID:11993680

  9. Transport of Elements By Geothermal And Volcanic Vapor

    NASA Astrophysics Data System (ADS)

    Kaasalainen, H. S.; Stefánsson, A.; Prapaipong, P.; Giroud, N.; Arnórsson, S.; Shock, E.

    2009-12-01

    Volatile species provide information on physical and chemical origin and processes in volcanic geothermal systems. Volatile metals and metalloids may be transported by both liquid and vapor phases that are often present in these systems, and some elements (e.g. As, Hg, Pb) may even be enriched in the vapor phases. The speciation and transport mechanism, as well as the origin of the elements in vapor is often poorly understood. Our aim is to characterize elemental concentrations and transport mechanism in the vapor phase in active geothermal systems. Samples of geothermal and volcanic vapor were collected from two-phase well discharges from Iceland and high temperature fumaroles in Vulcano Island and Solfatara field in Italy. Vapor and liquid phases were analyzed for major components and trace elements. Single phase volcanic vapor discharges had temperatures between 144 and 407°C. Their composition was dominated by H2O, but contained significant amounts of CO2 and acid gases (SO2, HCl, HF) whereas also H2S, H2 and N2 were present. In geothermal steam, with discharge pressures up to 42 bars, acid gases were absent and the steam consisted of 99% H2O, the rest being CO2, H2S, N2, and H2. Volcanic vapor condensates were analyzed for over 50 trace elements. Precipitation of condensate samples upon sampling and storage is commonly encountered problem. Different sampling protocols and sample treatments were tested to avoid and study their effects on the measured concentrations. The measured concentrations of some elements (e.g. Mg, Al, Sb) were found to show significant differences depending on the treatment, where as others (e.g. B, Ni, Zn) were not affected. In volcanic vapor, metals and metalloids were found in concentrations from lower ppb level up to tens of ppm. B shows highest concentrations followed by e.g. As, Pb, Zn, Mn, Ni, and Cu. In two phase well discharges, however, metals and metalloids were observed to be depleted in vapor compared to the liquid phase

  10. Atomic vapor laser isotope separation process

    DOEpatents

    Wyeth, R.W.; Paisner, J.A.; Story, T.

    1990-08-21

    A laser spectroscopy system is utilized in an atomic vapor laser isotope separation process. The system determines spectral components of an atomic vapor utilizing a laser heterodyne technique. 23 figs.

  11. Vertical Water Vapor Distribution at Phoenix

    NASA Astrophysics Data System (ADS)

    Tamppari, L. K.; Lemmon, M. T.

    2016-09-01

    The Phoenix SSI camera data along with radiative transfer modeling are used to retrieve the vertical water vapor profile. Preliminary results indicate that water vapor is often confined near the surface.

  12. Boiler for generating high quality vapor

    NASA Technical Reports Server (NTRS)

    Gray, V. H.; Marto, P. J.; Joslyn, A. W.

    1972-01-01

    Boiler supplies vapor for use in turbines by imparting a high angular velocity to the liquid annulus in heated rotating drum. Drum boiler provides a sharp interface between boiling liquid and vapor, thereby, inhibiting the formation of unwanted liquid droplets.

  13. A colorimetric sensor array for detection of triacetone triperoxide vapor.

    PubMed

    Lin, Hengwei; Suslick, Kenneth S

    2010-11-10

    Triacetone triperoxide (TATP), one of the most dangerous primary explosives, has emerged as an explosive of choice for terrorists in recent years. Owing to the lack of UV absorbance, fluorescence, or facile ionization, TATP is extremely difficult to detect directly. Techniques that are able to detect generally require expensive instrumentation, need extensive sample preparation, or cannot detect TATP in the gas phase. Here we report a simple and highly sensitive colorimetric sensor for the detection of TATP vapor with semiquantitative analysis from 50 ppb to 10 ppm. By using a solid acid catalyst to pretreat a gas stream, we have discovered that a colorimetric sensor array of redox sensitive dyes can detect even very low levels of TATP vapor from its acid decomposition products (e.g., H(2)O(2)) with limits of detection (LOD) below 2 ppb (i.e., <0.02% of its saturation vapor pressure). Common potential interferences (e.g., humidity, personal hygiene products, perfume, laundry supplies, volatile organic compounds, etc.) do not generate an array response, and the array can also differentiate TATP from other chemical oxidants (e.g., hydrogen peroxide, bleach, tert-butylhydroperoxide, peracetic acid).

  14. A colorimetric sensor array for detection of triacetone triperoxide vapor.

    PubMed

    Lin, Hengwei; Suslick, Kenneth S

    2010-11-10

    Triacetone triperoxide (TATP), one of the most dangerous primary explosives, has emerged as an explosive of choice for terrorists in recent years. Owing to the lack of UV absorbance, fluorescence, or facile ionization, TATP is extremely difficult to detect directly. Techniques that are able to detect generally require expensive instrumentation, need extensive sample preparation, or cannot detect TATP in the gas phase. Here we report a simple and highly sensitive colorimetric sensor for the detection of TATP vapor with semiquantitative analysis from 50 ppb to 10 ppm. By using a solid acid catalyst to pretreat a gas stream, we have discovered that a colorimetric sensor array of redox sensitive dyes can detect even very low levels of TATP vapor from its acid decomposition products (e.g., H(2)O(2)) with limits of detection (LOD) below 2 ppb (i.e., <0.02% of its saturation vapor pressure). Common potential interferences (e.g., humidity, personal hygiene products, perfume, laundry supplies, volatile organic compounds, etc.) do not generate an array response, and the array can also differentiate TATP from other chemical oxidants (e.g., hydrogen peroxide, bleach, tert-butylhydroperoxide, peracetic acid). PMID:20949933

  15. Microwave-assisted fast vapor-phase transport synthesis of MnAPO-5 molecular sieves

    SciTech Connect

    Shao Hui; Yao Jianfeng; Ke Xuebin; Zhang Lixiong Xu Nanping

    2009-04-02

    MnAPO-5 was prepared by a microwave-assisted vapor-phase transport method at 180 deg. C in short times. The products were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectra, UV-vis spectroscopic measurement, NH{sub 3}-temperature-programmed desorption and esterification reaction. It was found that dry gels prepared with aluminum isopropoxide, phosphoric acid and manganese acetate could be transferred to MnAPO-5 in the vapors of triethylamine and water by the microwave-assisted vapor-phase transport method at 180 deg. C for less than 30 min. The crystallization time was greatly reduced by the microwave heating compared with the conventional heating. The resulting MnAPO-5 exhibited much smaller particle sizes, higher surface areas and slightly higher catalytic activity in the esterification of acetic acid and butyl alcohol than those prepared by the conventional vapor-phase transport method and hydrothermal synthesis.

  16. Evaporation rates and vapor pressures of individual aerosol species formed in the atmospheric oxidation of alpha- and beta-pinene.

    PubMed

    Bilde, M; Pandis, S N

    2001-08-15

    The semivolatile oxidation products (trans-norpinic acid, pinic acid, cis-pinonic acid, etc.) of the biogenic monoterpenes (alpha-pinene, beta-pinene, etc.) contribute to the atmospheric burden of particulate matter. Using the tandem differential mobility analysis (TDMA) technique evaporation rates of glutaric acid, trans-norpinic acid, and pinic acid particles were measured in a laminar flow reactor. The vapor pressure of glutaric acid was found to be log(p0 glutaric/Pa) = - 3,510 K/T + 8.647 over the temperature range 290-300 K in good agreement with the values previously reported by Tao and McMurry (1989). The measured vapor pressure of trans-norpinic acid over the temperature range 290-312 K is log(p0 norpinic/Pa) = - 2,196.9 K/T + 3.522, and the vapor pressure of pinic acid is log(p0 pinic/ Pa) = - 5,691.7 K/T + 14.73 over the temperature range 290-323 K. The uncertainty on the reported vapor pressures is estimated to be approximately +/- 50%. The vapor pressure of cis-pinonic acid is estimated to be of the order of 7 x 10(-5) Pa at 296 K.

  17. 40 CFR 796.1950 - Vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 32 2011-07-01 2011-07-01 false Vapor pressure. 796.1950 Section 796... (CONTINUED) CHEMICAL FATE TESTING GUIDELINES Physical and Chemical Properties § 796.1950 Vapor pressure. (a... the vapor pressure of chemical and on environmental conditions which influence diffusion from...

  18. 40 CFR 796.1950 - Vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 33 2013-07-01 2013-07-01 false Vapor pressure. 796.1950 Section 796... (CONTINUED) CHEMICAL FATE TESTING GUIDELINES Physical and Chemical Properties § 796.1950 Vapor pressure. (a... the vapor pressure of chemical and on environmental conditions which influence diffusion from...

  19. 40 CFR 796.1950 - Vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 32 2014-07-01 2014-07-01 false Vapor pressure. 796.1950 Section 796... (CONTINUED) CHEMICAL FATE TESTING GUIDELINES Physical and Chemical Properties § 796.1950 Vapor pressure. (a... the vapor pressure of chemical and on environmental conditions which influence diffusion from...

  20. 40 CFR 796.1950 - Vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 33 2012-07-01 2012-07-01 false Vapor pressure. 796.1950 Section 796... (CONTINUED) CHEMICAL FATE TESTING GUIDELINES Physical and Chemical Properties § 796.1950 Vapor pressure. (a... the vapor pressure of chemical and on environmental conditions which influence diffusion from...

  1. Vapor-Resistant Heat-Pipe Artery

    NASA Technical Reports Server (NTRS)

    Dussinger, Peter M.; Shaubach, Robert M.; Buchko, Matt

    1991-01-01

    Vapor lock in heat pipe delayed or prevented. Modifications of wick prevent flow of vapor into, or formation of vapor in, liquid-return artery. Small pores of fine-grained sintered wick help to prevent formation of large bubbles. Slotted tube offers few nucleation sites for bubbles. Improves return of liquid in heat pipe.

  2. 40 CFR 796.1950 - Vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... adsorptivity onto solids, or high solubility in water are less likely to vaporize and become airborne than chemicals with high vapor pressures or with low water solubility or low adsorptivity to solids and sediments... 0 °C. (iv) “Vapor pressure” is the pressure at which a liquid or solid is in equilibrium with...

  3. Vapor Pressure Measurements in a Closed System

    ERIC Educational Resources Information Center

    Iannone, Mark

    2006-01-01

    An alternative method that uses a simple apparatus to measure vapor pressure versus temperature in a closed system, in which the total pressure is the vapor pressure of the liquid sample, is described. The use of this apparatus gives students a more direct picture of vapor pressure than the isoteniscope method and results have generally been quite…

  4. Stratospheric Sulfuric Acid and Black Carbon Aerosol Measured During POLARIS and its Role in Ozone Chemistry

    NASA Technical Reports Server (NTRS)

    Strawa, Anthony W.; Pueschel, R. F.; Drdla, K.; Verma, S.; Gore, Warren J. (Technical Monitor)

    1998-01-01

    Stratospheric aerosol can affect the environment in three ways. Sulfuric acid aerosol have been shown to act as sites for the reduction of reactive nitrogen and chlorine and as condensation sites to form Polar Stratospheric Clouds, under very cold conditions, which facilitate ozone depletion. Recently, modeling studies have suggested a link between BCA (Black Carbon Aerosol) and ozone chemistry. These studies suggest that HNO3, NO2, and O3 may be reduced heterogeneously on BCA particles. The ozone reaction converts ozone to oxygen molecules, while HNO3 and NO2 react to form NOx. Finally, a buildup of BCA could reduce the single-scatter albedo of aerosol below a value of 0.98, a critical value that has been postulated to change the effect of stratospheric aerosol from cooling to warming. Correlations between measured BCA amounts and aircraft usage have been reported. Attempts to link BCA to ozone chemistry and other stratospheric processes have been hindered by questions concerning the amount of BCA that exists in the stratosphere, the magnitude of reaction probabilities, and the scarcity of BCA measurements. The Ames Wire Impactors (AWI) participated in POLARIS as part of the complement of experiments on the NASA ER-2. One of our main objectives was to determine the amount of aerosol surface area, particularly BCA, available for reaction with stratospheric constituents and assess if possible, the importance of these reactions. The AWI collects aerosol and BCA particles on thin Palladium wires that are exposed to the ambient air in a controlled manner. The samples are returned to the laboratory for subsequent analysis. The product of the AWI analysis is the size, surface area, and volume distributions, morphology and elemental composition of aerosol and BCA. This paper presents results from our experiments during POLARIS and puts these measurements in the context of POLARIS and other missions in which we have participated. It describes modifications to the AWI data

  5. Functioning of antimony film electrode in acid media under cyclic and anodic stripping voltammetry conditions.

    PubMed

    Sebez, Bine; Ogorevc, Bozidar; Hocevar, Samo B; Veber, Marjan

    2013-06-27

    New insights into the functioning, i.e. electrochemical behaviour and analytical performance, of in situ prepared antimony film electrodes (SbFEs) under square-wave anodic stripping (SW-ASV) and cyclic (CV) voltammetry conditions are presented by studying several key operational parameters using Pb(II), Cd(II) and Zn(II) as model analyte ions. Five different carbon- and metal-based substrate transducer electrodes revealed a clear advantage of the former ones while the concentration of the precursor Sb(III) ion exhibited a distinct influence on the ASV functioning of the SbFE. Among six acids examined as potential supporting electrolytes the HNO3 was demonstrated to yield nearly identical results in conducting ASV experiments with SbFE as so far almost exclusively used HCl. This is extremely important as HNO3 is commonly employed acidifying agent in trace metal analysis, especially in elemental mass spectrometry measurements. By carrying out a systematic CV and ASV investigation using a medium exchange protocol, we confirmed the formation of poorly soluble oxidized Sb species at the substrate electrode surface at the end of each stripping step, i.e. at the potentials beyond the anodic dissolution of the antimony film. Hence, the significance of the cleaning and initializing the surface of a substrate electrode after accomplishing a stripping step was thoroughly studied in order to find conditions for a complete removal of the adhered Sb-oxides and thus to assure a memory-free functioning of the in situ prepared SbFE. Finally, the practical analytical application of the proposed ASV method was successfully tested and evaluated by measuring the three metal analytes in ground (tap) and surface (river) water samples acidified with HNO3. Our results approved the appropriateness of the SbFE and the proposed method for measuring low μg L(-1) levels of some toxic metals, particularly taking into account the possibility of on-field testing and the use of low cost

  6. Production of higher quality bio-oils by in-line esterification of pyrolysis vapor

    SciTech Connect

    Hilten, Roger Norris; Das, Keshav; Kastner, James R; Bibens, Brian P

    2014-12-02

    The disclosure encompasses in-line reactive condensation processes via vapor phase esterification of bio-oil to decease reactive species concentration and water content in the oily phase of a two-phase oil, thereby increasing storage stability and heating value. Esterification of the bio-oil vapor occurs via the vapor phase contact and subsequent reaction of organic acids with ethanol during condensation results in the production of water and esters. The pyrolysis oil product can have an increased ester content and an increased stability when compared to a condensed pyrolysis oil product not treated with an atomized alcohol.

  7. Vapor stabilizing surfaces for superhydrophobicity

    NASA Astrophysics Data System (ADS)

    Patankar, Neelesh

    2010-11-01

    The success of rough substrates designed for superhydrophobicity relies crucially on the presence of air pockets in the roughness grooves. This air is supplied by the surrounding environment. However, if the rough substrates are used in enclosed configurations, such as in fluidic networks, the air pockets may not be sustained in the roughness grooves. In this work a design approach based on sustaining a vapor phase of the liquid in the roughness grooves, instead of relying on the presence of air, is explored. The resulting surfaces, referred to as vapor stabilizing substrates, are deemed to be robust against wetting transition even if no air is present. Applications of this approach include low drag surfaces, nucleate boiling, and dropwise condensation heat transfer, among others.

  8. Active Hydrazine Vapor Sampler (AHVS)

    NASA Technical Reports Server (NTRS)

    Young, Rebecca C.; Mcbrearty, Charles F.; Curran, Daniel J.

    1993-01-01

    The Active Hydrazine Vapor Sampler (AHVS) was developed to detect vapors of hydrazine (HZ) and monomethylhydrazine (MMH) in air at parts-per-billion (ppb) concentration levels. The sampler consists of a commercial personal pump that draws ambient air through paper tape treated with vanillin (4-hydroxy-3-methoxybenzaldehyde). The paper tape is sandwiched in a thin cardboard housing inserted in one of the two specially designed holders to facilitate sampling. Contaminated air reacts with vanillin to develop a yellow color. The density of the color is proportional to the concentration of HZ or MMH. The AHVS can detect 10 ppb in less than 5 minutes. The sampler is easy to use, low cost, and intrinsically safe and contains no toxic material. It is most beneficial for use in locations with no laboratory capabilities for instrumentation calibration. This paper reviews the development, laboratory test, and field test of the device.

  9. Effect of acid concentration on closed-vessel microwave-assisted digestion of plant materials

    NASA Astrophysics Data System (ADS)

    Araújo, Geórgia C. L.; Gonzalez, Mário H.; Ferreira, Antônio G.; Nogueira, Ana Rita A.; Nóbrega, Joaquim A.

    2002-12-01

    The efficiency of microwave-assisted acid digestion of plants using different concentrations of nitric acid (2.0, 3.0, 5.0, 7.0 and 14 mol l -1) with hydrogen peroxide (30% v/v) was evaluated by measuring the residual carbon content (RCC) using inductively coupled plasma optical emission spectrometry (ICP-OES) with axial viewing. Certified reference materials were used for evaluating the accuracy attained when 2 mol l -1 HNO 3 was employed for digestion. Under all experimental conditions RCC values were always lower than 13% w/v, and even the highest concentration did not cause any interference with element recovery. It seems that the high pressure reached for closed-vessel operation improved the oxidative action of nitric acid due to consequent temperature increase, even when this reagent was not used at high concentrations. According to acid-base titration data, residual acid in the digestates varied from 1.2 to 4.0 mol l -1, depending on the acid concentration initially added. It can be concluded that for plant materials, microwave-assisted acid digestion can be carried out under mild conditions, which implies that digestates do not need extensive dilution before introduction by pneumatic nebulization to ICP-OES. An additional advantage is the lower amount of residue generated when working with less concentrated acid solutions.

  10. Vapor deposition of tantalum and tantalum compounds

    SciTech Connect

    Trkula, M.

    1996-04-01

    Tantalum, and many of its compounds, can be deposited as coatings with techniques ranging from pure, thermal chemical vapor deposition to pure physical vapor deposition. This review concentrates on chemical vapor deposition techniques. The paper takes a historical approach. The authors review classical, metal halide-based techniques and current techniques for tantalum chemical vapor deposition. The advantages and limitations of the techniques will be compared. The need for new lower temperature processes and hence new precursor chemicals will be examined and explained. In the last section, they add some speculation as to possible new, low-temperature precursors for tantalum chemical vapor deposition.

  11. What Good is Raman Water Vapor Lidar?

    NASA Technical Reports Server (NTRS)

    Whitman, David

    2011-01-01

    Raman lidar has been used to quantify water vapor in the atmosphere for various scientific studies including mesoscale meteorology and satellite validation. Now the international networks of NDACC and GRUAN have interest in using Raman water vapor lidar for detecting trends in atmospheric water vapor concentrations. What are the data needs for addressing these very different measurement challenges. We will review briefly the scientific needs for water vapor accuracy for each of these three applications and attempt to translate that into performance specifications for Raman lidar in an effort to address the question in the title of "What good is Raman water vapor Iidar."

  12. Vaporization Would Cool Primary Battery

    NASA Technical Reports Server (NTRS)

    Bhandari, Pradeep; Miyake, Robert N.

    1991-01-01

    Temperature of discharging high-power-density primary battery maintained below specified level by evaporation of suitable liquid from jacket surrounding battery, according to proposal. Pressure-relief valve regulates pressure and boiling temperature of liquid. Less material needed in cooling by vaporization than in cooling by melting. Technique used to cool batteries in situations in which engineering constraints on volume, mass, and location prevent attachment of cooling fins, heat pipes, or like.

  13. Evaporation by mechanical vapor recompression

    NASA Astrophysics Data System (ADS)

    Iverson, C. H.; Coury, G. E.

    1980-04-01

    Progress in the development of a study of the application of the technologies of mechanical vapor recompression and falling film evaporation as applied to the beet sugar industry is reported. Progress is reported in the following areas: technical literature search; report on visit to European factories using these technologies; energy balance studies of factories offered by the industry as candidates for the demonstration plants; and report on energy balance studies and the recommendations as to the site for the demonstration plant.

  14. Chemical vapor deposition of sialon

    DOEpatents

    Landingham, R.L.; Casey, A.W.

    A laminated composite and a method for forming the composite by chemical vapor deposition are described. The composite includes a layer of sialon and a material to which the layer is bonded. The method includes the steps of exposing a surface of the material to an ammonia containing atmosphere; heating the surface to at least about 1200/sup 0/C; and impinging a gas containing N/sub 2/, SiCl/sub 4/, and AlCl/sub 3/ on the surface.

  15. Studies on Vapor Adsorption Systems

    NASA Technical Reports Server (NTRS)

    Shamsundar, N.; Ramotowski, M.

    1998-01-01

    The project consisted of performing experiments on single and dual bed vapor adsorption systems, thermodynamic cycle optimization, and thermal modeling. The work was described in a technical paper that appeared in conference proceedings and a Master's thesis, which were previously submitted to NASA. The present report describes some additional thermal modeling work done subsequently, and includes listings of computer codes developed during the project. Recommendations for future work are provided.

  16. A novel chemically selective siloxane polymer for chemical vapor sensing

    NASA Astrophysics Data System (ADS)

    Huang, Jia; Jiang, Yadong; Du, Xiaosong; Bi, Juan

    2010-10-01

    A new hydrogen-bond acidic carbosiloxane polymer for quartz crystal microbalance sensors (QCMs) application was synthesized via O-alkylation, Claisen rearrange, hydrosilylation reaction and functionalized the polysiloxane with trifluoroacetone groups (TFA). The trifluoroisopropanol functionalized polysiloxane was characterized by FT-IR and 1HNMR. And this novel siloxane polymer was coated onto AT-cut 8 MHz QCM sensors to investigate its gas sensitive responses to the organophosphorus nerve agent stimulant dimethyl methylphosphonate (DMMP) vapor as well as other interfering organic vapors. The research work indicated that frequency shifts of the trifluoroisopropanol functionalized polysiloxane based QCM sensor to the DMMP vapor were completely linear, and with a regression coefficient of 0.9973 in the concentration range of 10-60 ppm. In addition, the sensitivity of the fabricated QCM sensors to DMMP was up to 10.64 Hz/ ppm, and much higher than the other interfering vapors, limits of detection (LODs) of the QCM sensors was 0.28 ppm, thus high selectivity to DMMP was demonstrated in this work.

  17. Critical points of metal vapors

    SciTech Connect

    Khomkin, A. L. Shumikhin, A. S.

    2015-09-15

    A new method is proposed for calculating the parameters of critical points and binodals for the vapor–liquid (insulator–metal) phase transition in vapors of metals with multielectron valence shells. The method is based on a model developed earlier for the vapors of alkali metals, atomic hydrogen, and exciton gas, proceeding from the assumption that the cohesion determining the basic characteristics of metals under normal conditions is also responsible for their properties in the vicinity of the critical point. It is proposed to calculate the cohesion of multielectron atoms using well-known scaling relations for the binding energy, which are constructed for most metals in the periodic table by processing the results of many numerical calculations. The adopted model allows the parameters of critical points and binodals for the vapor–liquid phase transition in metal vapors to be calculated using published data on the properties of metals under normal conditions. The parameters of critical points have been calculated for a large number of metals and show satisfactory agreement with experimental data for alkali metals and with available estimates for all other metals. Binodals of metals have been calculated for the first time.

  18. Water vapor diffusion membrane development

    NASA Technical Reports Server (NTRS)

    Tan, M. K.

    1977-01-01

    An application of the water vapor diffusion technique is examined whereby the permeated water vapor is vented to space vacuum to alleviate on-board waste storage and provide supplemental cooling. The work reported herein deals primarily with the vapor diffusion-heat rejection (VD-HR) as it applies to the Space Shuttle. A stack configuration was selected, designed and fabricated. An asymmetric cellulose acetate membrane, used in reverse osmosis application was selected and a special spacer was designed to enhance mixing and promote mass transfer. A skid-mount unit was assembled from components used in the bench unit although no attempt was made to render it flight-suitable. The operating conditions of the VD-HR were examined and defined and a 60-day continuous test was carried out. The membranes performed very well throughout the test; no membrane rupture and no unusual flux decay was observed. In addition, a tentative design for a flight-suitable VD-HR unit was made.

  19. Vapor pressure of water nanodroplets.

    PubMed

    Factorovich, Matías H; Molinero, Valeria; Scherlis, Damián A

    2014-03-26

    Classical thermodynamics is assumed to be valid up to a certain length-scale, below which the discontinuous nature of matter becomes manifest. In particular, this must be the case for the description of the vapor pressure based on the Kelvin equation. However, the legitimacy of this equation in the nanoscopic regime can not be simply established, because the determination of the vapor pressure of very small droplets poses a challenge both for experiments and simulations. In this article we make use of a grand canonical screening approach recently proposed to compute the vapor pressures of finite systems from molecular dynamics simulations. This scheme is applied to water droplets, to show that the applicability of the Kelvin equation extends to unexpectedly small lengths, of only 1 nm, where the inhomogeneities in the density of matter occur within spatial lengths of the same order of magnitude as the size of the object. While in principle this appears to violate the main assumptions underlying thermodynamics, the density profiles reveal, however, that structures of this size are still homogeneous in the nanosecond time-scale. Only when the inhomogeneity in the density persists through the temporal average, as it is the case for clusters of 40 particles or less, do the macroscopic thermodynamics and the molecular descriptions depart from each other.

  20. Desorption of 137Cs from Brachythecium mildeanum moss using acid solutions with pH 4.60-6.50

    NASA Astrophysics Data System (ADS)

    Čučulović, Ana; Veselinović, Dragan

    2015-12-01

    The desorption of 137Cs from the moss Brachythecium mildeanum (Schimp.) was performed using the following solutions: H2SO4 ( I), HNO3 ( II), H2SO4 + HNO3 ( III) with pH values of 4.60, 5.15, and 5.75, respectively, as well as distilled water (D) with pH 6.50. After five successive desorptions, each lasting 24 h, 20.5-37.6% 137Cs was desorbed from the moss using these solutions, while 30.7% of the starting content was desorbed using distilled water. The first desorption removed the highest percent of the original content of 137Cs in the moss (11.3-18.4%). This was determined by measuring 137Cs activity. If the current results are compared with those obtained earlier it may be concluded that 137Cs desorption from mosses is not species-dependent. The obtained results indicate the necessity of investigating the influence of acid rain, or rather, of H+ ions, on desorption of other ions from biological systems, i.e., the role of H+ ions in spreading other polluting compounds and thus producing secondary environmental pollution. From the results of this study it follows that acid rain will lead, through H+ ion action, to a similar increasing pollution of fallout waters with other ionic compounds which may not be present in the water before the contact with the plants and thus enable the pollution spreading. In the investigated system, the replacement of H+ ions from acid rains by more dangerous radioactive ions occured, increasing the concentration of the radioactive ions in the water, which demonstrates that the same process takes place in fallout water.