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  • 11
    Digitale Medien
    Digitale Medien
    Study of metal aerosol systems as a sink for atmospheric SO2 (1986)
    Springer
    Journal of atmospheric chemistry 4 (1986), S. 311-334 
    Details
    ISSN: 1573-0662
    Schlagwort(e): Sulfur dioxide ; removal ; aerosol ; transition metal ; hydrogen peroxide ; flow reactor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract The chemical removal of SO2 in the presence of different aerosol systems has been investigated in laboratory experiments using a dynamic flow reactor. The aerosols consisted of wetted particles containing one of the following substances: MnCl2, Mn(NO3)2, MnSO4, CuCl2, Cu(NO3)2, CuSO4, FeCl3, NaCl. The SO2 removal rate R was measured as a function of the SO2 gas phase concentration (SO2)g, the spatial metal concentration CMe, and the relative humidity rH in the reactor. A first-order dependence with regard to (SO2)g was observed for each type of aerosol. For the Mn(II) and Cu(II) aerosols R was found to be a non-linear function of CMe except for MnSO4 and Cu(NO3)2 particles. The removal rate showed a significant increase with the relative humidity particularly when rH was close to the deliquescence point of the wetted particles. Among the Mn(II) and Cu(II) aerosols investigated Mn(NO3)2 was found to be most efficient for the chemical removal of SO2 at atmospheric background conditions, especially in haze and fog droplets. The results further indicate that the catalytic oxidation of S(IV) in such aerosol systems may be as efficient as its oxidation by H2O2 in cloud water.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00053807
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  • 12
    Digitale Medien
    Digitale Medien
    A comparison of the enzyme fluorometric and the peroxyoxalate chemiluminescence methods for measuring H2O2 (1987)
    Springer
    Journal of atmospheric chemistry 5 (1987), S. 311-322 
    Details
    ISSN: 1573-0662
    Schlagwort(e): Enzyme fluorometry ; peroxyoxalate chemiluminescence ; hydrogen peroxide analysis ; comparative study
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract During September 25 to October 28, 1985, the enzyme fluorometric (Lazrus et al., 1985) and the peroxyoxalate chemiluminescence (Klockow and Jacob, 1986; Jaeschke, 1986) techniques for analyzing H2O2 were compared in laboratory studies at the National Center for Atmospheric Research in Boulder, Colorado, U.S.A. and under field conditions at the Whiteface Mt. field station of the Atmospheric Sciences Research Center, Albany, New York, U.S.A. Both methods showed excellent agreement, with a maximum deviation of ±5%. Only at unusually high concentrations of some potential atmospheric species could slight interferences be observed. During the experiments the detection limits were 1.3×10-8 mol/l (0.44 ppbm) of H2O2 for the fluorometric instrument and 4×10-8 mol/l (1.36 ppbm) of H2O2 for the chemiluminescence instrument. For the chemiluminescence technique, the response to methylhydroperoxide was approximately 80-fold less than that to an equivalent concentration of H2O2.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00114109
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  • 13
    Digitale Medien
    Digitale Medien
    Measurements of Trace Substances in the Arctic Troposphere as Potential Precursors and Constituents of Arctic Haze (1999)
    Springer
    Journal of atmospheric chemistry 34 (1999), S. 291-319 
    Details
    ISSN: 1573-0662
    Schlagwort(e): arctic air pollution ; precursor substances ; vertical profiles ; ozone ; PAN ; SO2 ; gaseous HNO3 ; particulate nitrate ; sulfate ; ammonium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract During two measuring campaigns in early spring 1994 and 1995 (March/April) and one campaign in summer 1994, measurements of ozone, PAN, sulfur dioxide, nitric acid, and particulate nitrate, sulfate, and ammonium (only 1995) were recorded in the Arctic. Observations were made by aircraft at various sites in the eastern and western Arctic. Ozone concentrations showed a steady increase with altitude both in spring and summer. During five flights in springtime, low ozone events (LOEs) could be observed near the surface and up to altitudes of 2000 m. SO2 background concentrations, ranging from detection limit (0.5 nmol/m3) to 5 nmol/m3, were observed during both spring and summer. Distinct maxima up to 55 nmol/m3 in lower altitudes were only obtained in springtime. Concentrations of the organic nitrate PAN were within a similar range as those of the inorganic nitrate HNO3 during spring campaigns. In contrast, concentrations of particulate nitrate were one half an order of magnitude lower. HNO3 concentrations increased significantly with altitude. Evidently, HNO3 was intruded from the stratosphere into the troposphere. Sulfate concentrations ranged between 5 and 30 nmol/m3; ammonium concentrations were obtained within a range from 10 to 50 nmol/m3.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006277230042
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  • 14
    Digitale Medien
    Digitale Medien
    A comparison between natural and anthropogenic emissions of the reduced sulfur compounds H2S, COS, and CS2 in a tropical industrialized region (1996)
    Springer
    Journal of atmospheric chemistry 25 (1996), S. 251-270 
    Details
    ISSN: 1573-0662
    Schlagwort(e): reduced sulfur compounds ; ambient concentrations ; gas exchange ; anthropogenic emissions ; natural emissions ; local budget ; Brazil
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract Extensive ambient concentration and flux measurements have been performed in the heavily polluted region of Cubatão/Brazil. Substantial contribution of anthropogenic sources to the local reduced sulfur burden has been observed. As a result of this atmospheric sulfur burden average gas exchange between vegetated soils and the atmosphere shows net deposition. Based mainly on own field measurements a local budget for H2S, COS, and CS2 has been made up in order to calculate anthropogenic emissions. All major sources and sinks in the chosen atmospheric reservoir (24×20×1 km) have been taken into account. Due to the small reservoir size fluxes across its boundaries are dominant sources and sinks. The differences between outflux and influx therefore account for the unknown anthropogenic emissions which have been determined to be 80±10 (H2S), 66±15 (COS), and 29±6 Mmol year-1 (CS2). Other sources and sinks like natural emissions, chemical conversion, and dry deposition turned out to be of minor importance on a local scale. In fact, inside the investigated reservoir natural emissions were below 0.5% of anthropogenic emissions. Anthropogenic emissions of H2S, COS, and CS2 quantified in this work have been compared with global emission estimates for these compounds made by other authors. We conclude that global anthropogenic emissions of reduced sulfur compounds especially of COS and CS2 are currently under-estimated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00053795
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  • 15
    Digitale Medien
    Digitale Medien
    GERG round-robin test of Z-meters, a Burnett apparatus, and an interferometric device for pVT measurements (1990)
    Springer
    International journal of thermophysics 11 (1990), S. 157-168 
    Details
    ISSN: 1572-9567
    Schlagwort(e): Burnett apparatus ; compressibility factor ; density ; ethane ; methane ; mixtures ; nitrogen ; refractive index ; Z-meter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The European Gas Research Group (GERG; Groupe Européen de Recherches Gazières) initiated a round-robin test of six Z-meters manufactured by Desgranges et Huot, a Burnett apparatus, and an interferometric device to back up the pVT data of the Z-meters. Two gas mixtures were measured. One mixture contained 49.7 mol% of methane and 50.3 mol% of nitrogen; the second mixture 81.3 mol% of methane, 16.4 mol% of ethane, and 2.3 mol% of propane. The test temperatures were mainly 280 and 300 K for the first mixture and 290 and 320 K for the second mixture. The maximum pressures were 8 MPa for Z-meters and 12 MPa for the Burnett apparatus and the grating interferometer. The experimental compressibility factors Z of the six Z-meters are generally in agreement within ±0.05%. The agreement with the reference data from the Burnett apparatus and the refractive index measurements is also within ± 0.05%. Only two isotherms of the binary mixtures differ by about 0.1% from the other data. Recent natural gas measurements show substantially the same results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00503867
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  • 16
    Digitale Medien
    Digitale Medien
    Calculation of the compressibility factor of natural gases based on the calorific value and the specific gravity (1990)
    Springer
    International journal of thermophysics 11 (1990), S. 145-156 
    Details
    ISSN: 1572-9567
    Schlagwort(e): calorific value ; compressibility factor ; equation of state ; natural gas ; mixtures ; specific gravity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The measurement of large volume flows of natural gas in transmission lines requires an accurate equation of state for pressures up to about 12 MPa and in the temperature range from 265 to 335 K. If a detailed analysis of the gas mixture is available, one of the possibilities is to use the virial equation of state. However, such a gas analysis is time-consuming and expensive and, therefore, not always practical. We have developed a new equation which is based on the virial equation but requires limited input data. In general, for any given natural gas, the gross calorific value, the specific gravity, and the mole fractions of nitrogen and carbon dioxide are known. It will be shown that a knowledge of three of these four quantities is sufficient for an accurate prediction of the compressibility factor of the natural gas.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00503866
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  • 17
    Digitale Medien
    Digitale Medien
    Ideal-gas thermodynamic properties for natural-gas applications (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1381-1392 
    Details
    ISSN: 1572-9567
    Schlagwort(e): caloric properties ; equation of state ; ideal gas ; isobaric heat capacity ; natural gas ; speed of sound
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Calculating caloric properties from a thermal equation of state requires information such as isobaric heat capacities in the ideal-gas state as a function of temperature. In this work, values for the parameters of thec p 0 correlation proposed by Aly and Lee were newly determined for 21 pure gases which are compounds of natural gas mixtures. The values of the parameters were adjusted to selectedc p 0 data calculated from spectroscopic data for temperatures ranging from 10 to 1000 K. The data sources used are discussed and compared with literature data deduced from theoretic models and caloric measurements. The parameters presented will be applied in a current GERG project for evaluating equations of state (e.g., the AGA 8 equation) for their suitability for calculating caloric properties.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02083547
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  • 18
    Digitale Medien
    Digitale Medien
    The determination of the second and third virial coefficients frompVT-X data of binary systems (1988)
    Springer
    International journal of thermophysics 9 (1988), S. 985-992 
    Details
    ISSN: 1572-9567
    Schlagwort(e): compressibility ; data analysis ; mixtures ; virial coefficients
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The compressibility factor of multicomponent systems can be obtained in terms of virial coefficients of the pure components and their binary mixtures. This paper concerns a method with which, for that purpose, the second and third virial coefficients for these binaries have been determined from experimental data. From useful data, second and third virial coefficients are obtained as a quadratic function of the temperature. The density domain for which these results are applicable is discussed. When ample data are available, results for a sample mixture can be obtained in a straightforward manner. Nevertheless, it is shown that under much less favorable conditions—sometimes even when pure-component data are lacking—fairly good results can still be obtained. In that case, the choice for an appropriate combining rule has to be considered carefully. Finally, the involvement of ternary mixture data, both obtained experimentally and predicted by the equation, is considered.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01133266
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  • 19
    Digitale Medien
    Digitale Medien
    Determination of the interaction second virial coefficients for the carbon dioxide-ethane system from refractive index measurements (1987)
    Springer
    International journal of thermophysics 8 (1987), S. 81-95 
    Details
    ISSN: 1572-9567
    Schlagwort(e): carbon dioxide ; ethane ; Lorentz-Lorenz law ; mixtures ; refraction virial coefficient ; interaction second virial coefficient ; compressibility factor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The compressibility behavior of the CO2-C2H6 system was investigated experimentally. In this work, the refractive indexes of the pure gases and the mixtures were measured using an optical apparatus. On the basis of these data, density and compressibility factors were computed using the Lorentz-Lorenz law. For the pure components, carbon dioxide and ethane, the data from the optical system were slightly adjusted by a fit to Burnett apparatus data measured separately. The experiments produced very accurate virial coefficients and refraction virial coefficients. This paper reports on the effect of temperature on the second and third virial coefficients. For the first refraction virial coefficient, no influence of temperature was found with the equipment used. The interaction second virial coefficient B 12 (as a function of temperature) was computed from experimental data for the CO2-C2H6 binary system. The data, for which an accuracy of ±1.5 cm3 · mol−1 was estimated, are in agreement with the data published by Holste et al.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00503226
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  • 20
    Digitale Medien
    Digitale Medien
    Direct determination of the second refractivity virial coefficient of methane, nitrogen, and five of their mixtures (1986)
    Springer
    International journal of thermophysics 7 (1986), S. 357-366 
    Details
    ISSN: 1572-9567
    Schlagwort(e): expansion technique ; Lorentz-Lorenz function ; mixed interaction ; refractive index ; refractivity virial coefficient
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The experimental technique for the direct determination of the second refractivity virial coefficient is described. The absolute measurement of the refractive index n combined with an expansion technique for obtaining the higher-order coefficients of the Lorentz-Lorenz expansion $${\text{LL = [(}}n^2 - 1)/(n^2 + 2)]{\text{ }}\rho ^{ - 1} {\text{ = }}A_n {\text{ }} + {\text{ }}B_n \rho {\text{ }} + {\text{ }}C_n \rho ^2 {\text{ + }} \cdot \cdot \cdot $$ leads to precise values of density ρ. A nis the ideal molar refractivity, which is readily determined from the absolute measurements of n in terms of pressure, whereas B n, C n,... are the higher-order molar refractivity virial coefficients, which are obtained from expansion experiments. The expansion method consists in measuring the sum of optical path lengths of two similar cells: one of them is filled with the gas at density ρ, and the other is evacuated. After the expansion the density is nearly halved and one measures again the optical path lengths. In order to cancel the small differences in volume and path lengths between the two cells, the process is reversed. Because the linear term in density remains the same before and after the expansion and only the quadratic and higher-order terms change, we can determine the refractivity virial coefficients B n, C n,... from the change in the optical path lengths. The measurements for the determination of B nand C nfor methane, nitrogen, and five mixtures were carried out at 323.15 K and pressures up to 450 bar. The mixed-interaction constant for methane and nitrogen derived from the experimental second refractivity virial coefficient is compared with those obtained from the geometric and linear mixing rule as well as Lorentz combination.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00500161
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