TY - JOUR A1 - van der Hout, J. W. A1 - van der Veen, A. M. H. A1 - Ziel, P. R. A1 - Kipphardt, Heinrich A1 - Tuma, Dirk A1 - Maiwald, Michael A1 - Fernández, T. E. A1 - Gómez, C. A1 - Cieciora, D. A1 - Ochman, G. A1 - Dias, F. A1 - Silvino, V. A1 - Macé, T. A1 - Sutour, C. A1 - Marioni, F. A1 - Ackermann, A. A1 - Niederhauser, B. A1 - Fükő, J. A1 - Büki, T. A1 - Szilágyi, Z. N. A1 - Tarhan, T. A1 - Engin, E. T1 - International Comparison Euramet.QM-K111 – Propane in Nitrogen N2 - This key comparison aims to assess the core capabilities of the participants in gas analysis. Such competences include, among others, the capabilities to prepare Primary Standard gas Mixtures (PSMs), perform the necessary purity analysis on the materials used in the gas mixture preparation, the verification of the composition of newly prepared PSMs against existing ones, and the capability of calibrating the composition of a gas mixture. According to the Strategy for Key Comparisons of the Gas Analysis Working Group, this key comparison is classified as an RMO track A key comparison. The artefacts were binary mixtures of propane in nitrogen at a nominal amount-of-substance fraction level of 1000 μmol/mol. The values and uncertainties from the gravimetric gas mixture preparation were used as key comparison reference values (KCRVs). Each transfer standard had its own KCRV. The results are generally good. All results are within ± 1 % of the KCRV. KW - EURAMET.QM-K111 KW - Propane in nitrogen PY - 2017 DO - https://doi.org/10.1088/0026-1394/54/1A/08020 SN - 0026-1394 VL - 54 IS - Technical Supplement SP - 08020, 1 EP - 34 PB - IOP Science AN - OPUS4-44471 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kumelan, J. A1 - Tuma, Dirk A1 - Maurer, G. ED - Renon, H. T1 - Simultaneous solubility of carbon dioxide and hydrogen in the ionic liquid [hmim][Tf2N]: experimental results and correlation N2 - The solubility of a single gas as well as the simultaneous solubility of several gases in an ionic liquid is of great interest in many areas of chemical engineering, particularly in heterogeneous catalysis. One of the most interesting features involved in the study of the simultaneous solubility of several gases in a pure ionic liquid is the difference between experimental data and predictions for the simultaneous solubility (based on experimental data for the solubility of the single gases). The well soluble gas might act as a cosolvent or as an antisolvent for a sparsely soluble second gas. New experimental results and a correlation are presented for the simultaneous solubility of hydrogen (i.e., a sparsely soluble gas) and carbon dioxide (a well soluble gas) in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([hmim][Tf2N]) at temperatures between 293 K and 373 K and pressures up to about 9.2 MPa. The experimental results reveal that carbon dioxide acts as a cosolvent for hydrogen in that particular ionic liquid. A correlation shows that the cosolvency effect can be modeled by considering interaction parameters between hydrogen and carbon dioxide in liquid [hmim][Tf2N]. The correlation can also be used to quantify that cosolvency effect: one mole of carbon dioxide in 1000 g of [hmim][Tf2N] increases the solubility of (small amounts of) hydrogen by about 20%. KW - Simultaneous solubility of gases KW - Carbon dioxide KW - Hydrogen KW - Ionic liquids KW - [hmim][Tf2N] KW - 1-Hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide PY - 2011 DO - https://doi.org/10.1016/j.fluid.2011.08.013 SN - 0378-3812 VL - 311 SP - 9 EP - 16 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-24559 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pham, Q.L. A1 - Haldorai, Y. A1 - Nguyen, V.H. A1 - Tuma, Dirk A1 - Shim, J.-J. T1 - Facile synthesis of poly(p-phenylenediamine)/MWCNT nanocomposites and characterization for investigation of structural effects of carbon nanotubes N2 - Poly(p-phenylenediamine) (PpPD)/carboxylic acid-functionalized multiwalled carbon nanotubes (c-MWCNTs) nanocomposites were prepared by chemical oxidative polymerization using potassium persulfate (K2S2O8) as an oxidant. Field-emission scanning electron microscopy (FE–SEM) and field-emission Transmission electron microscopy (FE–TEM) showed that a tubular layer of PpPD was coated on the surface of carbon nanotubes with a thickness of 10–20 nm. FT–IR analysis provided an evidence for the formation of nanocomposites. The thermal stability of nanocomposites was improved by addition of c-MWCNTs as confirmed by thermogravimetric analysis (TGA). XRD spectra showed that the crystalline nature of PpPD was not affected much by the addition of c-MWCNTs. As the content of c-MWCNTs was increased, the electrical conductivity of the nanocomposites increased due to the interaction between polymer and nanotubes that enhances electron delocalization. KW - p-Phenylenediamine KW - Multi-walled carbon nanotube KW - Nanocomposite KW - Oxidative polymerization PY - 2011 SN - 0250-4707 SN - 0973-7669 VL - 34 IS - 1 SP - 37 EP - 43 PB - Indian Academy of Sciences CY - Bangalore AN - OPUS4-24339 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tuma, Dirk T1 - Towards a European Infrastructure for the Characterisation of Energy Gases T2 - 2nd IMEKO TC 11 International Symposium Metrological Infrastructure CY - Cavtat, Croatia DA - 2011-06-15 PY - 2011 AN - OPUS4-24304 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ulanova, T. A1 - Tuma, Dirk A1 - Maurer, G. T1 - Phase equilibria and partitioning of L-histidine and three pharmaceuticals to pH-adjusted high-pressure liquid phases of the ternary system (ethene + water + 2-propanol) N2 - Adding some salt to a homogeneous aqueous liquid solution of an organic solvent often results in a liquid–liquid phase split. However, such a phase split can also be achieved by charging such a liquid with a gas, in particular when the temperature is close to the critical temperature of that specific gas. This phenomenon is called 'salting out by a near-critical gas'. It might be applied in a high-pressure extraction process, for example, to separate and recover valuable biomolecules from aqueous phases. Using a neutral gas like, for example, ethene for pressurizing additionally allows to adjust the pH of the coexisting liquid phases and to influence the partitioning of biomolecules when they change their electric net charge with the pH of the solution. The design of such separation processes requires not only reliable information on the phase forming system, that is, the ternary system (near-critical gas + water + organic solvent), but also on the partitioning of typical solutes to the coexisting phases. The present publication reports data (from an experimental study with a static-analytical device) for the partitioning of four biomolecules, that is, L-histidine, Aspirin, cimetidine, and 4-dimethylaminoantipyrine (at nearly infinite dilution) to coexisting liquid phases of the high-pressure three-phase liquid–liquid–vapor (L1L2V) equilibrium of the ternary system (ethene + water + 2-propanol) at (293 and 333) K and pressures from about (5.5 to 17) MPa. The coexisting liquid phases are characterized by distinctly different compositions, the aqueous phase being more hydrophilic than the alkanol-rich phase. Moreover, electrolytes were additionally added to adjust the pH conditions in the liquid phases. The pH-dependent dissociation equilibrium and the related net charge of the biomolecules primarily determine the partitioning behavior: The pH effect is stronger than the impact of varying pressure or temperature. For example, a switch from basic to acidic conditions can invert the partitioning, if that switch at the same time effects a change in the net charge of the solute, for example, from an ionic to a neutral molecule (or vice versa). The ionic solute is more hydrophilic (and thus prefers the aqueous phase), whereas the neutral or zwitterionic solute is less hydrophilic (i.e., more lipophilic) and consequently prefers the propanol-rich liquid phase. KW - Wirkstoffe KW - Bioverfahrenstechnik KW - Extraktion KW - Mischphasenthermodynamik PY - 2011 DO - https://doi.org/10.1021/je2001914 SN - 0021-9568 VL - 56 IS - 12 SP - 4376 EP - 4391 PB - Soc. CY - Washington, DC, USA AN - OPUS4-25899 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kumelan, J. A1 - Kamps, A.P.-S. A1 - Tuma, Dirk A1 - Maurer, G. T1 - Solubility of carbon dioxide in liquid mixtures of water + [bmim][CH3SO4] N2 - Experimental results are reported for the solubility of carbon dioxide in liquid mixtures of water and the ionic liquid 1-n-butyl-3-methylimidazolium methylsulfate ([bmim][CH3SO4]). Three (gas-free) solvent compositions were considered with mass fractions of [bmim][CH3SO4] of w' ≈ 0.15, 0.50, and 0.87 (mole fractions x' ≈ 0.013, 0.066, and 0.33). In the isothermal experimental series, the temperature was about (293, 333, and 373) K. The total pressure ranged up to about 10 MPa. The molality of carbon dioxide in the solvent mixture of (water + [bmim][CH3SO4]) (the mole fraction of carbon dioxide in the liquid) ranged up to approximately 1.64 mol·kg–1 (about 0.0332). The experimental results are used to determine Henry's constant of carbon dioxide in the liquid mixtures of (water + [bmim][CH3SO4]) as well as the partial molar volume of that gas at infinite dilution in those solvent mixtures. The phase equilibrium is described by applying an extension (to solvent mixtures) of Pitzer's molality scale-based equation for the Gibbs excess energy. KW - Gaslöslichkeit KW - Ionische Flüssigkeit KW - Mischphasenthermodynamik PY - 2011 DO - https://doi.org/10.1021/je200477s SN - 0021-9568 VL - 56 IS - 12 SP - 4505 EP - 4515 PB - Soc. CY - Washington, DC, USA AN - OPUS4-25898 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tuma, Dirk T1 - Neue Untersuchungen zum Phänomen "Aussalzen mit einem nahekritischen Gas" T2 - Jahrestreffen des Fachausschusses Hochdruckverfahrenstechnik der DECHEMA e. V. CY - Maribor, Slovenia DA - 2011-03-10 PY - 2011 AN - OPUS4-26706 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tuma, Dirk T1 - Gas solubility in ionic liquids T2 - 243rd American Chemical Society National Meeting & Exposition CY - San Diego, CA, USA DA - 2012-03-25 PY - 2012 AN - OPUS4-26704 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bremser, Wolfgang A1 - Tuma, Dirk T1 - International reference values for calibration of process gas chromatographs (PGCs) and related uncertainties N2 - In a mutual framework agreement, the two German national institutes BAM (Federal Institute of Materials Research and Testing) and PTB (Physikalisch-Technische Bundesanstalt) agreed upon the development, provision, and dissemination of national measurement standards for chemical analysis via primary reference measuring systems. Traceability to national standards and international comparability is of key importance for the acceptance of measurement results in metrology. T2 - 6th International Gas Analysis Symposium & Exhibition -- GAS 2011 CY - Rotterdam, The Netherlands DA - 09.02.2011 KW - Metrology KW - Gas standards KW - Certification PY - 2011 AN - OPUS4-35943 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tuma, Dirk A1 - Hernández-Gómez, R. A1 - Gómez-Hernández, A. A1 - Chamorro, C. R. T1 - Accurate experimental (p, rho, T) data for the introduction of hydrogen into the natural gas grid: Thermodynamic characterization of the nitrogen−hydrogen binary system from 240 to 350 K and pressures up to 20 MPa N2 - The experimental density data of the binary System nitrogen−hydrogen available at the time of the development of the equation of state for natural gases and related mixtures, GERG-2008, were limited to hydrogen contents higher than 0.15 (amount-of-substance fraction) and temperatures above 270 K. This work provides accurate experimental (p, ρ, T) data for three binary mixtures of nitrogen and hydrogen: (0.95 N2 + 0.05 H2), (0.90 N2 + 0.10 H2), and (0.50 N2 + 0.50 H2) at temperatures of 240, 250, 260, 275, 300, 325, and 350 K, thus extending the range of available experimental data to low hydrogen contents and low temperatures. The density measurements were performed by using a single-sinker densimeter with magnetic suspension coupling at pressures up to 20 MPa. Experimental data were compared with the corresponding densities calculated from the GERG-2008 and the AGA8-DC92 equations of state. The relative deviations of the experimental data from both equations of state were within the estimated uncertainty value of the equations. Therefore, the experimental data agree very well with the values estimated from the equations. The virial coefficients B(T,x), C(T,x), and D(T,x) as well as the second interaction virial coefficient B12(T) for the nitrogen−hydrogen binary system were also calculated from the experimental data set at temperatures from 240 to 350 K. The resulting values agree with those from literature. KW - Binary mixtures KW - Density measurements KW - GERG-2008 equation of state PY - 2017 DO - https://doi.org/10.1021/acs.jced.7b00694 SN - 0021-9568 VL - 62 IS - 12 SP - 4310 EP - 4326 PB - American Chemical Society CY - Washington DC AN - OPUS4-43832 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tuma, Dirk T1 - High-pressure gas solubility and associated phase equilibria in systems with ionic liquids 14. - 19.03.2010, T2 - EUCHEM Conference on MOlten Salts and Ionic Liquids 2010 CY - Bamberg, Germany DA - 2010-03-14 PY - 2010 AN - OPUS4-21583 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chobanov, K. A1 - Tuma, Dirk A1 - Maurer, G. ED - Renon, H. T1 - High-pressure phase behavior of ternary systems (carbon dioxide + alkanol + hydrophobic ionic liquid) N2 - Some homogeneous liquid mixtures of an ionic liquid and a lower alkanol (e.g., methanol) can be forced to undergo a liquid–liquid phase split (resulting in a three-phase liquid–liquid–vapor (L1L2V) equilibrium) by pressurization with a gas. Such systems exhibit the phenomenon of "salting out by a nearcritical gas". That phenomenon is often observed at temperatures around the critical temperature of the gas in liquid mixtures where at least one of the liquid components is a good solvent for that gas. New experimental results for both the L1L2V equilibrium and the corresponding critical endpoint lines of the two ternary systems (carbon dioxide + methanol + 1-n-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6]) and (carbon dioxide + 1-butanol + 1-n-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide [hmim][Tf2N]) at temperatures between 293 and 333 K are reported. The experiments were performed with an "analytical method". The liquid–liquid phase split exists only at pressures between a lower critical endpoint line (where both liquid phases become critical and coexist with a vapor phase) and an upper critical endpoint line (where one of the phases becomes critical with the vapor phase while the critical phases coexist with another liquid phase). The compositions of the coexisting three phases L1, L2, and V differ considerably; a high-density, ionic liquid-rich liquid phase (L1) coexists with an alkanol-rich liquid phase (L2) of lower density and a vapor phase (V) that is virtually ionic liquid-free. For both systems, it was observed that, at constant temperature, increasing pressure shifts the L1 phase towards higher contents of ionic liquid and gas and less alkanol, whereas in the L2 phase the mole fractions of ionic liquid and alkanol decrease. Higher temperatures result in a smaller difference between the pressures of both critical endpoint lines. Experimental results for both critical endpoint lines and for the compositions of the coexisting liquid phases are reported. KW - Room-temperature ionic lilquids KW - [bmim][PF6] and [hmim][Tf2N] KW - Alkanol KW - Carbon dioxide KW - High-pressure phase equilibria KW - Salting-out behavior KW - Critical endpoints PY - 2010 DO - https://doi.org/10.1016/j.fluid.2010.02.015 SN - 0378-3812 VL - 294 IS - 1-2 SP - 54 EP - 66 PB - Elsevier CY - Amsterdam AN - OPUS4-22060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kalies, G. A1 - Rockmann, R. A1 - Tuma, Dirk A1 - Gapke, J. T1 - Ordered mesoporous solids as model substances for liquid adsorption N2 - Two different ordered mesoporous solids, a hexagonal SBA-15 silica sample and its inverse CMK-3 carbon structure were applied in liquid-phase adsorption. By means of the analysis of experimental data of a binary liquid model mixture with one polar and one non-polar component, the general way is outlined how to obtain essential and trustworthy solid information from liquid-phase adsorption. KW - Adsorption excess isotherm KW - Ordered mesoporous solid KW - Binary liquid mixture KW - Thermodynamics KW - Solid heterogeneity PY - 2010 DO - https://doi.org/10.1016/j.apsusc.2009.12.091 SN - 0169-4332 SN - 1873-5584 VL - 256 IS - 17 SP - 5395 EP - 5398 PB - North-Holland CY - Amsterdam AN - OPUS4-22064 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -