TY - CONF A1 - Tuma, Dirk T1 - Thermophysical properties of hydrogen-containing mixtures for the extension of equation-of-state models for natural gas N2 - The decarbonization of the energy sector is driving the interest in hydrogen as an energy-storage medium. A practical alternative to transport and distribute H2 is using the existing infrastructure for natural gas. The GERG-2008 equation of state currently serves as the ISO standard (ISO 20765-2) for the calculation of thermodynamic properties of natural gas, but H2 appears only as a secondary component. The availability of consolidated data for mixtures with H2 available at the time of its constitution was very limited. The experimental characterization of the thermodynamic behavior of mixtures of H2 with the main components of natural gas is thus of great relevance to validate and improve the GERG-2008 equation of state for its use with H2-enriched natural gas. T2 - Thermodynamik-Kolloquium 2021 CY - Online meeting DA - 27.09.2021 KW - Hydrogen-containing mixtures KW - Density measurements KW - Equations of state PY - 2021 AN - OPUS4-53991 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhou, Z. A1 - Han, Q. A1 - Wang, D. A1 - Macé, T. A1 - Kipphardt, Heinrich A1 - Maiwald, Michael A1 - Tuma, Dirk A1 - Uehara, S. A1 - Akima, D. A1 - Shimosaka, T. A1 - Jung, J. A1 - Oh, S.-H. A1 - van der Veen, A. A1 - van Wijk, J.I.T. A1 - Ziel, P. R. A1 - Konopelko, L. A1 - Valkova, M. A1 - Mogale, D.M. A1 - Botha, A. A1 - Brewer, P. A1 - Murugan, A. A1 - Minnaro, M.D. A1 - Miller, M. A1 - Guenther, F. A1 - Kelly, M.E. T1 - CCQM K101 Final report international comparison CCQM-K101:Oxygen in nitrogen-a track B comparison and that the matrix contains argon N2 - This key comparison aims to assess the capabilities of the participants to determine the amount-of-substance fraction oxygen in nitrogen. The GAWG has classified this as a track B comparison, due to the unexpected 50 μmol/mol argon mole fraction content of the transfer standards, which effects the achievable performance of some measurement techniques such a GC-TCD. The separation of oxygen and argon is challenging, and not all systems in use are equally well designed for it. As this analytical challenge due to a substantial fraction of argon in the transfer standards became a reality, the Gas Analysis Working Group (GAWG) decided to qualify this key comparison as a regular key comparison and not as a core comparison, which may be used to support calibration and measurement capabilities (CMCs) for oxygen in nitrogen, or for oxygen in nitrogen mixtures containing argon only (see also the section on support to CMCs). KW - CCQM-K101 KW - Gas analysis PY - 2016 UR - http://iopscience.iop.org/article/10.1088/0026-1394/53/1A/08013 SN - 1681-7575 SN - 0026-1394 VL - 53 IS - Techn Suppl SP - 08013, 1 EP - 71 PB - IOP publishing AN - OPUS4-40013 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Culleton, L.P. A1 - Brown, A. A1 - Murugan, A. A1 - Van der Veen, A. A1 - Van Osselen, D. A1 - Ziel, P. R. A1 - Li, J. A1 - Tuma, Dirk A1 - Schulz, Gert A1 - Näther, Stephanie A1 - Arrhenius, K. A1 - Kühnemuth, D. A1 - Beránek, J. A1 - Fuko, J. A1 - Val'ková, M. T1 - Results of an international comparison on the analysis of real nonconventional energy gases N2 - The requirement for a metrological infrastructure to ensure the interchangability of 'nonconventional’ energy gases within existing European infrastructure1 was the driving force behind the work undertaken in the three-year EMRP Characterisation of energy gases project EMRP ENG01 (June 2010 - May 2013). As part of work package one of the project, Standards and methods were used to perform composition and impurity measurements on samples of real energy gases collected from around Europe. The aim of this study was to compare the results obtained from different labs, and thereby provide an evaluation of the labs’ capabilities and provide insight into the feasibility of different analytical methodologies for use with future measurements. KW - Energy gases KW - Real samples KW - Sampling KW - Analysis PY - 2013 SN - 1754-2928 IS - July SP - 1 EP - 28 PB - Queen's Printer and Controller of HMSO CY - Teddington, Middlesex, UK AN - OPUS4-29449 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tuma, Dirk T1 - Kalorimetrische Bestimmung des Brennwerts nicht-konventioneller Brenngase und Vergleich mit analytischer Methodik T2 - VDI-Expertenforum Thermodynamik-Kolloquium 2013 CY - Hamburg, Germany DA - 2013-10-07 PY - 2013 AN - OPUS4-29274 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tuma, Dirk T1 - Gaslöslichkeiten und Hochdruckphasengleichgewichte in ternären Systemen mit Beteiligung ionischer Flüssigkeiten T2 - Thermodynamik-Kolloquium der DECHEMA e.V. CY - Frankfurt am Main, Germany DA - 2011-10-04 PY - 2011 AN - OPUS4-29340 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tuma, Dirk T1 - Standards and methods for the analysis of coal mine methane, a "non-conventional" energy gas T2 - GAS 2013 CY - Rotterdam, Netherlands DA - 2013-06-05 PY - 2013 AN - OPUS4-29338 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hernández-Gómez, R. A1 - Tuma, Dirk A1 - Villamanan, M.A. A1 - Mondéjar, M.E. A1 - Chamorro, C.R. T1 - Accurate thermodynamic characterization of a synthetic coal mine methane mixture N2 - In the last few years, coal mine methane (CMM) has gained significance as a potential non-conventional gas fuel. The progressive depletion of common fossil fuels reserves and, on the other hand, the positive estimates of CMM resources as a by-product of mining promote this fuel gas as a promising alternative fuel. The increasing importance of its exploitation makes it necessary to check the capability of the present-day models and equations of state for natural gas to predict the thermophysical properties of gases with a considerably different composition, like CMM. In this work, accurate density measurements of a synthetic CMM mixture are reported in the temperature range from (250 to 400) K and pressures up to 15 MPa, as part of the research project EMRP ENG01 of the European Metrology Research Program for the characterization of non-conventional energy gases. Experimental data were compared with the densities calculated with the GERG-2008 equation of state. Relative deviations between experimental and estimated densities were within a 0.2% band at temperatures above 275 K, while data at 250 K as well as at 275 K and pressures above 10 MPa showed higher deviations. KW - Coal mine methane KW - Density measurements KW - Single sinker densimeter KW - GERG-2008 equation of state PY - 2014 DO - https://doi.org/10.1016/j.jct.2013.09.023 SN - 0021-9614 VL - 68 SP - 253 EP - 259 PB - Academic Press CY - London [u.a.] AN - OPUS4-29450 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lamiel, C. A1 - Lee, Y. R. A1 - Cho, M. H. A1 - Tuma, Dirk A1 - Shim, J.-J. T1 - Enhanced electrochemical performance of nickel-cobalt-oxide@reduced graphene oxide//activated carbon asymmetric supercapacitors by the addition of a redox-active electrolyte N2 - Supercapacitors are an emerging energy-storage system with a wide range of potential applications. In this study, highly porous nickel-cobalt-oxide@reduced graphene oxide (Ni-Co-O@RGO-s) nanosheets were synthesized as an active material for supercapacitors using a surfactant-assisted microwave irradiation technique. The RGO-modified nanocomposite showed a larger specific area, better conductivity, and lower resistivity than the unmodified nanocomposite because the RGO facilitated faster ion diffusion/transport for improved redox activity. The synergistic effect of Ni-Co-O@RGO-s resulted in a high capacitance of 1903 F/g (at 0.8 A/g) in a mixed KOH/redox active K3Fe(CN)6 electrolyte. The asymmetric Ni-Co-O@RGO-s//AC supercapacitor device yielded a high energy density and power density of 39 Wh/kg and 7500 W/kg, respectively. The porous structure and combination of redox couples from both the electrode and electrolyte provided a highly synergistic effect, which improved the performance of the supercapacitor device. KW - Ni-Co oxide KW - Reduced graphene oxide KW - Nanocomposite KW - Supercapacitor PY - 2017 DO - https://doi.org/10.1016/j.jcis.2017.08.003 SN - 0021-9797 SN - 1095-7103 VL - 507 SP - 300 EP - 309 PB - Elsevier Inc. CY - Amsterdam AN - OPUS4-41284 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mady, A. H. A1 - Baynosa, M. L. A1 - Tuma, Dirk A1 - Shim, J.-J. T1 - Facile microwave-assisted green synthesis of Ag-ZnFe2O4@rGO nanocomposites for efficient removal of organic dyes under UV- and visible-light irradiation N2 - Nanocomposites of Ag-ZnFe2O4@reduced graphene oxide (rGO) were synthesized using a one-pot microwave-assisted self-assembly method. The morphology and structure of the Ag-ZnFe2O4@rGO nanocomposites were characterized. The nanocomposites formed with 15.2 wt% rGO showed excellent adsorption properties and high photocatalytic activity for the degradation of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO). The synergistic interactions between Ag, ZnFe2O4, and rGO decreased the aggregation of the nanoparticles (NPs) and increased the surface area, resulting in better absorption in both UV and visible light. Such a structure was helpful for separating the photoexcited electron-hole pairs and accelerating electron transfer. Electrochemical impedance spectroscopy (EIS) revealed a smaller resistance in the solid-state interface layer and charge transfer on the composite surface than that of the bare ZnFe2O4 NPs and ZnFe2O4@rGO nanocomposite. The Ag-ZnFe2O4@rGO nanocomposite could be recovered easily by a magnet and reused five times with no significant decrease in photocatalytic activity. The as-prepared Ag-ZnFe2O4@rGO nanocomposite catalyst could be applied to the removal of hard-to-degrade waste materials owing to its high efficiency in both UV and visible light and its excellent reusability. KW - nanoparticles KW - microwave synthesis KW - photocatalysis PY - 2017 DO - https://doi.org/10.1016/j.apcatb.2016.10.033 SN - 0926-3373 SN - 1873-3883 VL - 203 SP - 416 EP - 427 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-37962 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tuma, Dirk A1 - Safarov, J. A1 - Sperlich, C. A1 - Namazova, A. A1 - Aliyev, A. A1 - Shahverdiyev, A. A1 - Hassel, E. T1 - Carbon dioxide solubility in 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium tetrachloroferrate over an extended range of temperature and pressure N2 - Solubility data of carbon dioxide (CO2) in the two ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4] and 1-butyl-3-methylimidazolium tetrachloroferrate [BMIM][FeCl4] at T = (273.15-413.15) K and pressures up to p = 4.5 MPa are presented. In Addition to the experiments, a literature review was done to compare the new results with published solubility data. The measurements were carried out using an isochoric method which operates in decrements of deltaT = 20 K within the investigated temperature range and at selected four different pressure steps ranging from a pressure p of around 4.5 MPa to around 0.5 MPa. The solubility of CO2 decreases in both ionic liquids with increasing temperatures. Within the p,T-range investigated, CO2 displayed a solubility in [BMIM][BF4] from a mole fraction x = 0.0117 and a corresponding molality m = 0.0526 mol/kg at T = 413.15 K and p = 0.417 MPa up to x = 0.4876 and m = 4.2094 mol/kg at T = 293.15 K and p = 4.349 MPa. The corresponding values for the solubility in [BMIM][FeCl4] start at a mole fraction x = 0.0268 and a corresponding molality m = 0.0818 mol/kg at T = 413.15 K and p = 0.443 MPa and end at x = 0.5126 and m = 3.1216 mol/kg at T = 293.15 K and p = 4.478 MPa. At a constant temperature, CO2 is better soluble in [BMIM][FeCl4] than in [BMIM][BF4] and the mean value of the solubility difference related to mole fraction x over the pressure range investigated amounts to about 4 % at T = 273.15 K and monotonously increases to about 92 % at T = 413.15 K. Henry's law constant as well as derived thermodynamic properties, such as the Gibbs energy of solvation, the enthalpy of solvation, the entropy of solvation, and the heat capacity of solvation, were calculated and discussed regarding the solute-solvent molecular interactions. KW - Ionic liquid KW - Gas solubility KW - Henry's law constant KW - Solvation properties PY - 2018 DO - https://doi.org/10.1016/j.fluid.2018.03.019 SN - 0378-3812 SN - 1879-0224 VL - 467 SP - 45 EP - 60 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-44892 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tuma, Dirk A1 - Hernández-Gomez, R. A1 - Pérez, E. A1 - Chamorro, C. R. T1 - Accurate experimental (p, ρ, and T) data for the introduction of hydrogen into the natural gas grid (II): Thermodynamic characterization of the methane−hydrogen binary system from 240 to 350 K and pressures up to 20 MPa N2 - Most of the experimental density data of the methane−hydrogen binary system available at the time of the development of the equation of state for natural gases and related mixtures, GERG-2008, at temperatures above 270 K were limited to hydrogen contents higher than 0.20 (amount-of-substance fraction). On the contrary, for mixtures with hydrogen contents lower than 0.20, experimental data were limited to temperatures below 270 K. This work intends to close the gap and provides accurate experimental (p, ρ, and T) data for three binary mixtures of methane and hydrogen, (0.95 CH4 + 0.05 H2), (0.90 CH4 + 0.10 H2), and (0.50 CH4 + 0.50 H2), at temperatures of 240, 250, 260, 275, 300, 325, and 350 K, thus extending the range of available experimental data to higher temperatures for mixtures with hydrogen contents lower than 0.20 and, accordingly, to lower temperatures for mixtures with hydrogen contents higher than 0.20. 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 to the corresponding densities calculated from the GERG-2008 and the AGA8-DC92 equations of state, respectively. The experimental data are within the uncertainty of both equations of state, except at the lower temperatures of 240 and 250 K and pressures over 14 MPa for the mixtures with a hydrogen content of 0.05 and 0.10, respectively. The virial coefficients B(T, x) and C(T, x), as well as the second interaction virial coefficient B12(T) for the methane−hydrogen binary system, were also calculated from the experimental data set at temperatures from 240 to 350 K using the virial equation of state. KW - Volumetric data KW - GERG-2008 equation of state KW - Hydrogen-containing mixture KW - Single-sinker densimeter PY - 2018 DO - https://doi.org/10.1021/acs.jced.7b01125 SN - 0021-9568 VL - 63 IS - 5 SP - 1613 EP - 1630 PB - ACS Publications CY - Washington DC AN - OPUS4-44890 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Flores, E. A1 - Idrees, F. A1 - Moussay, P. A1 - Viallon, J. A1 - Wielgosz, R. A1 - Fernández, T. A1 - Ramírez, S. A1 - Rojo, A. A1 - Shinji, U. A1 - Waldén, J. A1 - Sega, M. A1 - Sang-Hyub, O. A1 - Macé, T. A1 - Couret, C. A1 - Qiao, H. A1 - Smeulders, D. A1 - Guenther, F.R. A1 - Thorn, W.J. III A1 - Tshilongo, J. A1 - Ntsasa, N.G. A1 - Stovcík, V. A1 - Valková, M. A1 - Konopelko, L. A1 - Gromova, E. A1 - Nieuwenkamp, G. A1 - Wessel, R. M. A1 - Milton, M. A1 - Harling, A. A1 - Vargha, G. A1 - Tuma, Dirk A1 - Kohl, Anka A1 - Schulz, Gert T1 - Final report on international comparison CCQM-K74: Nitrogen dioxide, 10 µmol/mol N2 - There is a high international priority attached to activities which reduce NOx in the atmosphere. The current level of permitted emissions is typically between 50 µmol/mol and 100 µmol/mol, but lower values are expected in the future. Currently, ambient air quality monitoring regulations also require the measurement of NOx mole fractions as low as 0.2 µmol/mol. The production of accurate standards at these levels of mole fractions requires either dilution of a stable higher concentration gas standard or production by a dynamic technique, for example one based on permeation tubes. The CCQM-K74 key comparison was designed to evaluate the level of comparability of National Metrology Institutes' measurement capabilities and standards for nitrogen dioxide (NO2) at a nominal mole fraction of 10 µmol/mol. The measurements of this key comparison took place from June 2009 to May 2010. Seventeen laboratories took part in this comparison coordinated by the BIPM and VSL. The key comparison reference value was based on BIPM measurement results, and the standard measurement uncertainty of the reference value was 0.042 µmol/mol. This key comparison demonstrated that the results of the majority of the participants agreed within limits of ±3% relative to the reference value. The results of only one laboratory lay significantly outside these limits. Likewise this comparison made clear that a full interpretation of the results of the comparison needed to take into account the presence of nitric acid (in the range 100 nmol/mol to 350 nmol/mol) in the cylinders circulated as part of the comparison, as well as the possible presence of nitric acid in the primary standards used by participating laboratories. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA). DatesIssue 1A (Technical Supplement 2012) KW - Ringversuch KW - NO2 KW - Spurenverunreinigungen KW - Meßverfahren PY - 2012 DO - https://doi.org/10.1088/0026-1394/49/1A/08005 SN - 0026-1394 SN - 1681-7575 VL - 49 IS - 08005 SP - 1 EP - 117 PB - Inst. of Physics Publ. CY - Bristol AN - OPUS4-25927 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nieuwenkamp, G. A1 - Wessel, R. M. A1 - van der Veen, A.M.H. A1 - Ziel, P. R. A1 - Han, Q. A1 - Tuma, Dirk A1 - Woo, J.-C. A1 - Fuko, J.T. A1 - Szilágyi, N. A1 - Büki, T. A1 - Konopelko, L. A1 - Kustikov, Y.A. A1 - Popova, T.A. A1 - Pankratov, V.V. A1 - Pir, M.N. A1 - Nazarov, E.V. A1 - Ehvalov, L.V. A1 - Timofeev, A.U. A1 - Kuzmina, T.A. A1 - Meshkov, A.V. A1 - Valková, M. A1 - Pätoprsty, V. A1 - Downey, M. A1 - Vargha, G. A1 - Brown, A. A1 - Milton, M. T1 - International comparison CCQM-K77: Refinery gas N2 - Refinery gas is a complex mixture of hydrocarbons and non-combustible gases (e.g., carbon monoxide, carbon dioxide, nitrogen, helium). It is obtained as part of the refining and conversion of crude oil. This key comparison aims to evaluate the measurement capabilities for these types of mixtures. The results of the key comparison indicate that the analysis of a refinery-type gas mixture is for some laboratories a challenge. Overall, four laboratories (VSL, NIM, NPL and VNIIM) have satisfactory results. The results of some participants highlight some non-trivial issues, such as appropriate separation between saturated and unsaturated hydrocarbons, and issues with the measurement of nitrogen, hydrogen and helium. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA). DatesIssue 1A (Technical Supplement 2012) KW - Ringversuch KW - Raffineriegas KW - Chromatographische Analyse PY - 2012 DO - https://doi.org/10.1088/0026-1394/49/1A/08003 SN - 0026-1394 SN - 1681-7575 VL - 49 IS - 08003 SP - 1 EP - 71 PB - Inst. of Physics Publ. CY - Bristol AN - OPUS4-25931 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Flores, E. A1 - Idrees, F. A1 - Moussay, P. A1 - Viallon, J. A1 - Wielgosz, R. A1 - Fernández, T. A1 - Rojo, A. A1 - Ramírez, S. A1 - Aoki, N. A1 - Kato, K. A1 - Jeongsoon, L. A1 - Moon, D. A1 - Kim, J.-S. A1 - Harling, A. A1 - Milton, M. A1 - Smeulders, D. A1 - Guenther, F.R. A1 - Gameson, L. A1 - Botha, A. A1 - Tshilongo, J. A1 - Ntsasa, N.G. A1 - Valková, M. A1 - Konopelko, L. A1 - Kustikov, Y.A. A1 - Ballandovich, V. S. A1 - Gromova, E.V. A1 - Tuma, Dirk A1 - Kohl, Anka A1 - Schulz, Gert T1 - Final report of the pilot study CCQM-P110-B1: A comparison of nitrogen dioxide (NO2) in nitrogen standards at 10 µmol/mol by Fourier transform infrared spectroscopy (FT-IR) N2 - This pilot study compares the performance of participants in analyzing gas mixtures of nitrogen dioxide in nitrogen by comparison with in-house gravimetric standards using Fourier transformed infrared spectroscopy (FT-IR). In this study the same gas mixtures were used as in the key comparison CCQM-K74, which was designed to evaluate the level of comparability of National Metrology Institutes' measurement capabilities for nitrogen dioxide (NO2) at a nominal mole fraction of 10 µmol/mol. In the comparison CCQM-K74 most of the participants used chemiluminescence, with a small number using UV absorption or FT-IR spectroscopy, and thus it is of interest to improve understanding of the comparative performance of these techniques because they do not exhibit any cross-sensitivity to nitric acid (HNO3), which was known to be present in the mixtures used for the comparison. The results of this pilot study indicate good consistency and a level of agreement similar to that reported in the comparison CCQM-K74, demonstrating that FT-IR can be operated as a comparison method when calibrated with appropriate gas standards and can achieve similar measurement uncertainties to chemiluminescence and UV absorption techniques. An additional pilot study, CCQM-P110-B2, was conducted on the same gas mixtures in parallel with this pilot study. The second study addressed FT-IR spectroscopy when used to measure the gas mixtures with respect to reference spectra. The results of this second study will be reported elsewhere. Main text. To reach the main text of this paper, click on Final Report. The final report has been peer-reviewed and approved for publication by the CCQM-GAWG. DatesIssue 1A (Technical Supplement 2012) KW - Ringversuch KW - NO2 KW - Spurenverunreinigungen KW - FT-IR-Spektroskopie PY - 2012 DO - https://doi.org/10.1088/0026-1394/49/1A/08006 SN - 0026-1394 SN - 1681-7575 VL - 49 IS - 08006 SP - 1 EP - 76 PB - Inst. of Physics Publ. CY - Bristol AN - OPUS4-25928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tuma, Dirk A1 - Ulanova, T. A1 - Chobanov, K. A1 - Maurer, G. T1 - Neue Untersuchungen zum Phänomen Aussalzen mit einem nahekritischen Gas N2 - Untersuchungen zur gasinduzierten Phasentrennung bzw. zum Aussalzen mit nahekritischen Gasen wurden an verschiedenen wässrigen Lösungen (auch mit ionischem Fluid) durchgeführt. Ziel war der Nachweis und die Charakterisierung von Hochdruckmehrphasengleichgewichten, die sich für eine technische Anwendung eignen. Kriterien hierfür sind Auftreten des Flüssig/flüssig-Phasenzerfalls bei relativ niedrigem Druck, seine Existenz über einen weiten Druck- und Zusammensetzungsbereich und damit verbunden eine druckinduzierte Änderung der Zusammensetzung der koexistierenden Flüssigphasen. Die eingesetzten ionischen Fluide zeigen zwar das gewünschte Phasenverhalten, erfüllen die Kriterien aber nur teilweise. Im Vorgriff auf eine mögliche Anwendung wurde die Verteilung eines hochmolekularen, amphiprotischen Naturstoffs auf die koexistierenden Flüssigphasen untersucht und durch Einstellung des pH-Werts gezielt verändert. ------------------------------------------------------------------------------------------------------------------------------------- Investigations on gas-induced phase split, i.e., salting out by a nearcritical gas, were carried out for several aqueous solutions (including an ionic liquid). The research aimed to verify and characterize high-pressure multiphase equilibria that might be suitable for technical applications. The respective criteria are occurrence at relatively low pressures and the existence of the phase equilibrium phenomenon over a significant region of both composition and pressure, which is related to a pressure-induced significant alteration of the compositions of the coexisting liquid phases. The employed ionic liquids revealed the expected phase behavior but without full compliance of all criteria. In anticipation of an application, the partitioning of an amphiprotic, high-molecular biomolecule to the coexisting liquid phases was successfully administered via a pH variation. KW - Dampf/flüssig/flüssig-Gleichgewicht KW - Dissoziationsgleichgewicht KW - Ionische Fluide KW - Nahekritisches Gas KW - Dissociation equilibrium KW - Ionic liquids KW - Nearcritical gas KW - Ternary systems KW - Vapor-liquid-liquid equilibrium PY - 2012 DO - https://doi.org/10.1002/cite.201100180 SN - 0009-286X SN - 1522-2640 VL - 84 IS - 4 SP - 456 EP - 464 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-25930 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ziel, Ruben P. A1 - Zalewska, Ewelina A1 - van der Veen, Adriaan M. H. A1 - Kipphardt, Heinrich A1 - Tuma, Dirk A1 - Esteban, Andres Rojo A1 - Fernandez Vicente, Teresa Esperanza A1 - Mace, Tatiana A1 - Sutour, Christophe A1 - Marioni, Fabrice A1 - Fükö, Judit A1 - Szücs, László A1 - Büki, Tamás A1 - Szilágyi Nagyné, Zsófia A1 - Cieciora, Dariusz A1 - Ochman, Grzegorz A1 - Romanowski, Przemysław A1 - Lis, Anna A1 - Garnuszek, Magdalena A1 - Valkova, Miroslava A1 - Ackermann, Andreas A1 - Pascale, Celine A1 - Niederhauser, Bernhard A1 - Tarhan, Tanil A1 - Boztepe, Aylin A1 - Beránek, Jan A1 - Bárta, Miroslav T1 - International comparison EURAMET.QM-K3.2019 - Automotive exhaust gases N2 - EURAMET.QM-K3.2019 was a repeat of the key comparison EURAMET.QM-K3 on the composition of automotive exhaust gases. New in EURAMET.QM-K3.2019 was the addition of the amount fraction oxygen to the programme. The key comparison reference values were obtained independently, using static gravimetry and appropriate corrections from purity analysis and are linked to those of CCQM-K3.2019. The key comparison results show equivalence between the measurement standards maintained by the participating national metrology institutes. The demonstrated equivalence can be used to underpin services related to automotive exhaust gases as well as generically through the flexible scheme ("track A"). KW - CCQM KW - Automotive gases PY - 2023 DO - https://doi.org/10.1088/0026-1394/60/1A/08030 SN - 1681-7575 VL - 60 IS - 1A SP - 1 EP - 63 PB - IOP Publishing CY - Bristol AN - OPUS4-58904 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lozano-Martín, D. A1 - Tuma, Dirk A1 - Kipphardt, Heinrich A1 - Khanipour, Peyman A1 - Chamorro, C. R. T1 - Thermodynamic characterization of the (H2 + C3H8) system significant for the hydrogen economy: Experimental (p, rho, T) determination and equation-of-state modelling N2 - For the gradual introduction of hydrogen in the energy market, the study of the properties of mixtures of hydrogen with typical components of natural gas (NG) and liquefied petroleum gas (LPG) is of great importance. This work aims to provide accurate experimental (p, rho, T) data for three hydrogen-propane mixtures with nominal compositions (amount of substance, mol/mol) of (0.95 H2 + 0.05 C3H8), (0.90 H2 + 0.10 C3H8), and (0.83 H2 + 0.17 C3H8), at temperatures of 250, 275, 300, 325, 350, and 375 K, and pressures up to 20 MPa. A single-sinker densimeter was used to determine the density of the mixtures. Experimental density data were compared to the densities calculated from two reference equations of state: the GERG-2008 and the AGA8-DC92. Relative deviations from the GERG-2008 EoS are systematically larger than those from the AGA8-DC92. They are within the ±0.5% band for the mixture with 5% of propane, but deviations are higher than 0.5% for the mixtures with 10% and 17% of propane, especially at low temperatures and high pressures. Finally, the sets of new experimental data have been processed by the application of two different statistical equations of state: the virial equation of state, through the second and third virial coefficients, B(T, x) and C(T, x), and the PC-SAFT equation of state. KW - Hydrogen-containing gas mixture KW - Density data KW - Equation of state KW - Virial coefficients PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570056 DO - https://doi.org/10.1016/j.ijhydene.2022.11.170 SN - 0360-3199 VL - 48 IS - 23 SP - 8645 EP - 8667 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-57005 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lozano-Martín, Daniel A1 - Kipphardt, Heinrich A1 - Khanipour, Peyman A1 - Tuma, Dirk A1 - Horrillo, Alfonso A1 - Chamorro, César R. T1 - Impact of hydrogen addition, up to 20 % (mol/mol), on the thermodynamic (p, ρ, T) properties of a reference high-calorific natural gas mixture with significant ethane and propane content N2 - Injecting hydrogen into the natural gas grid supports gradual decarbonization. To check the accuracy of equations of state for hydrogen-enriched natural gas mixtures, precise density data from well-characterized reference mixtures are essential. In a prior study, we provided experimental measurements for a natural gas constituted mainly of methane and for two derived hydrogen-enriched mixtures. In the present study, being the second and final part of our investigation, density measurements for a high-calorific natural gas with significant ethane and propane content, along with two hydrogen-enriched variants (10 and 20 mol-% hydrogen) are provided. The mixtures are gravimetrically prepared following ISO 6142-1. Density measurements, conducted with a single-sinker densimeter at temperatures from (260–350) K and pressures up to 20 MPa, are compared with three equations of state: AGA8-DC92, GERG-2008, and an improved GERG-2008. Results indicate that all models perform better for methane-dominant mixtures than for those containing heavier hydrocarbons. KW - Hydrogen-enriched natural gas KW - High-pressure density KW - Reference equation of state PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-633371 DO - https://doi.org/10.1016/j.ijhydene.2025.05.173 SN - 0360-3199 VL - 140 SP - 256 EP - 271 PB - Elsevier BV CY - Amsterdam AN - OPUS4-63337 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lozano-Martín, D. A1 - Pazoki, F. A1 - Kipphardt, Heinrich A1 - Khanipour, P. A1 - Tuma, Dirk A1 - Horillo, A. A1 - Chamorro, C. R. T1 - Thermodynamic (p, ρ, T) characterization of a reference high-calorific natural gas mixture when hydrogen is added up to 20 % (mol/mol) N2 - The injection of hydrogen into the natural-gas grid is an alternative during the process of a gradual decarbonization of the heat and power supply. When dealing with hydrogen-enriched natural gas mixtures, the performance of the reference equations of state habitually used for natural gas should be validated by using high-precision experimental thermophysical data from multicomponent reference mixtures prepared with the lowest possible uncertainty in composition. In this work, we present experimental density data for an 11-compound high-calorific (hydrogen-free) natural gas mixture and for two derived hydrogen-enriched natural gas mixtures prepared by adding (10 and 20) mol-% of hydrogen to the original standard natural gas mixture. The three mixtures were prepared gravimetrically according to ISO 6142–1 for maximum precision in their composition and thus qualify for reference materials. A single-sinker densimeter was used to determine the density of the mixtures from (250–350) K and up to 20 MPa. The experimental density results of this work have been compared to the densities calculated by three different reference equations of state for natural gas related mixtures: the AGA8-DC92 EoS, the GERG-2008 EoS, and an improved version of the GERG-2008 EoS. While relative deviations of the experimental density data for the hydrogen-free natural gas mixture are always within the claimed uncertainty of the three considered equations of state, larger deviations can be observed for the hydrogen-enriched natural gas mixtures from any of the three equations of state, especially for the lowest temperature and the highest pressures. KW - Hydrogen-enriched natural gas KW - Single-sinker densimeter KW - High-pressure density KW - Equations of state PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604742 DO - https://doi.org/10.1016/j.ijhydene.2024.05.028 SN - 0360-3199 VL - 70 SP - 118 EP - 135 PB - Elsevier BV CY - Amsterdam AN - OPUS4-60474 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Golub, Tino Petar A1 - Meyer, Klas A1 - Paul, Andrea A1 - Kipphardt, Heinrich A1 - Tuma, Dirk T1 - Exploring the potential of a setup for combined quantification of hydrogen in natural gas – Raman and NMR spectroscopy N2 - An accurate measurement of the amount fraction of hydrogen in gas mixtures is mandatory for practical applications, requiring methods that are fast, continuous, robust, and cost-effective. This study compares the performance of Raman and benchtop NMR process spectroscopy for determining the hydrogen amount fraction in gas mixtures. A setup was designed to integrate both techniques, enabling measurements of the same sample. Tests were conducted with gravimetrically prepared gas mixtures of reference quality ranging from 1.20 cmol/mol to 85.83 cmol/mol of hydrogen. The results demonstrate that Raman spectroscopy provides superior performance, with a minimal root mean square error (RMSE) of 0.22 cmol/mol and excellent linearity. In contrast, benchtop NMR spectroscopy faced challenges, such as overlapping peaks and longer measurement times, resulting in a higher RMSE of 0.71 cmol/mol. Raman spectroscopy proves to be particularly well-suited for practical applications due to its high accuracy and linearity. Meanwhile, benchtop NMR spectroscopy holds potential for future enhancements through ongoing technological advances, such as higher magnetic field strengths. In summary, the results from our study indicate that Raman spectroscopy is already a serviceable method for precise hydrogen quantification, whereas benchtop NMR spectroscopy can be attributed potential for future applications. KW - Hydrogen amount fraction KW - Raman spectroscopy KW - NMR spectroscopy KW - Field applicability PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-610093 DO - https://doi.org/10.1016/j.saa.2024.125087 SN - 1386-1425 VL - 325 SP - 1 EP - 9 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-61009 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Segovia, J. J. A1 - Tuma, Dirk A1 - Lozano-Martín, D. A1 - Moreau, A. A1 - Martín, M. C. A1 - Vega-Maza, D. T1 - Speed of sound data and acoustic virial coefficients of two binary (N2 + H2) mixtures at temperatures between (260 and 350) K and at pressures between (0.5 and 20) MPa N2 - This work aims to address the technical concerns related to the thermodynamic characterization of gas mixtures blended with hydrogen for the implementation of hydrogen as a new energy vector. For this purpose, new experimental speed of sound measurements have been done in gaseous and supercritical phases of two binary mixtures of nitrogen and hydrogen using the most accurate technique available, i.e., the spherical acoustic resonator, yielding an experimental expanded (k = 2) uncertainty of only 220 parts in 106 (0.022%). The measurements cover the pressure range between (0.5 and 20) MPa, the temperature range between (260 and 350) K, and the composition range with a nominal mole percentage of hydrogen of (5 and 10) mol%, respectively. From the speed of sound data sets, thermophysical properties that are relevant for the characterization of the mixture, namely the second βa and third γa acoustic virial coefficients, are derived. These results are thoroughly compared and discussed with the established reference mixture models valid for mixtures of nitrogen and hydrogen, such as the AGA8-DC92 EoS, the GERG-2008 EoS, and the recently developed adaptation of the GERG-2008 EoS, here denoted GERG-H2_improved EoS. Special attention has been given to the effect of hydrogen concentration on those properties, showing that only the GERG-H2_improved EoS is consistent with the data sets within the experimental uncertainty in most measuring conditions. KW - Speed of sound KW - Acoustic resonance KW - Binary gas mixture PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-551482 DO - https://doi.org/10.1016/j.jct.2022.106791 SN - 0021-9614 VL - 171 SP - 1 EP - 13 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-55148 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lozano-Martín, D. A1 - Tuma, Dirk A1 - Vega-Maza, D. A1 - Martín, M. C. A1 - Chamorro, C. R. T1 - Thermodynamic characterization of the (CO2+ O2) binary system for the development of models for CCS processes: Accurate experimental (p, rho, T) data and virial coefficients N2 - Continuing our study on (CO2 + O2) mixtures, this work reports new experimental (p, rho, T) data for two oxygen-rich mixtures with mole fractions x(O2) = (0.50 and 0.75) mol·mol−1, in the temperature range T = (250–375) K and pressure range p = (0.5–20) MPa, using a single-sinker densimeter. Experimental density data were compared to two well-established equation-of-state models: EOS-CG and GERG-2008. In the p, T-range investigated, the EOS-CG gave a better reproduction for the equimolar mixture (x(O2) = 0.5), whereas the GERG-2008 performed significantly better for the oxygen-rich mixture (x(O2) = 0.75). The EOS-CG generally overestimates the density, while the GERG-2008 underestimates it. This complete set of new experimental data, together with previous measurements, is used to calculate the virial coefficients B(T, x) and C(T, x), as well as the second interaction virial coefficient B12(T) for the (CO2+ O2) system. KW - Binary mixtures CO2 + O2 KW - Density measurements KW - Equations of state KW - Virial coefficients PY - 2021 DO - https://doi.org/10.1016/j.supflu.2020.105074 SN - 0896-8446 VL - 169 SP - 5074 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-51670 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baynosa, M. L. A1 - Mady, A. H. A1 - Nguyen, V. Q. A1 - Kumar, D. R. A1 - Sayed, M. S. A1 - Tuma, Dirk A1 - Shim, J.-J. T1 - Eco-friendly synthesis of recyclable mesoporous zinc ferrite@reduced graphene oxide nanocomposite for efficient photocatalytic dye degradation under solar radiation N2 - Zinc ferrite and graphene composites have attracted considerable attention in wastewater treatment. In this work, a magnetically separable mesoporous composite of ZnFe2O4 nanoparticles (NPs) and reduced graphene oxide (rGO) was prepared through a simple and eco-friendly method with pure water as solvent and without the need for subsequent thermal treatment. Uniformly dispersed ZnFe2O4 NPs on the surface of rGO sheets exhibited good crystallinity and a large BET specific surface area. These factors contributed to good photocatalytic performance of the composite for the degradation of methylene blue (MB) under simulated solar-light radiation, increased adsorptivity, increased separation efficiency of the photo-excited charges on the surface of the catalyst, and broadened light-absorption range of the composite. Efficient interfacial interaction between the ZnFe2O4 NPs and rGO sheets resulted in synergistic effects. The magnetically separable ZnFe2O4@rGO nanocomposite proved an efficient and stable catalyst in three consecutive photodegradation cycles for MB dye in aqueous solution under solar radiation. In addition, the synthesis method proposed in this study could be scaled-up easily due to the simplicity of the process, the lack of a toxic reagent, and the use of low temperatures. KW - Zinc ferrite KW - Reduced graphene oxide KW - Nanocomposite KW - Wastewater PY - 2020 DO - https://doi.org/10.1016/j.jcis.2019.11.018 SN - 0021-9797 VL - 561 SP - 459 EP - 469 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-50211 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dahmen, N. A1 - Deiters, U. K. A1 - Tuma, Dirk T1 - In Memoriam - Professor Dr. rer. nat. Gerhard Manfred Schneider (May 7, 1932 - October 16, 2020) - Professor and Chair of Physical Chemistry, Ruhr-University, Bochum, Germany (1969-1997) N2 - Professor Gerhard Schneider, a truly dedicated researcher, teacher, and pioneer in the field of high-pressure science, passed away on October 16th, 2020. It is with deep gratitude that we remember him here. KW - Obituary KW - Physical Chemistry KW - Phase Equilibria PY - 2021 DO - https://doi.org/10.1016/j.supflu.2021.105219 SN - 0896-8446 VL - 174 SP - 1 EP - 2 PB - Elsevier CY - Amsterdam AN - OPUS4-52457 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Shiflett, M. B. A1 - Magee, J. W. A1 - Tuma, Dirk ED - Shiflett, M. B. T1 - Important Developments in the History of Ionic Liquids from Academic Curiosity to Commercial Processes and Products N2 - Twenty years ago, research involving ionic liquids was a minor field of interest, and only a few chemists and even fewer engineers were interested in salts with melting points near room temperature. In April 2000, the first NATO advanced research workshop on ionic liquids was held in Heraklion, Crete. The conference was the first international meeting devoted to ionic liquids and attracted most of the active researchers at that time. Following that meeting, activity in the field began to flourish and the first books and international conferences devoted to ionic liquids began to appear. By the end of 2018, more than 80,000 scientific papers had been published, and 17,000 patents were applied for in the field of ionic liquids! This book provides an overview of the current and emerging industrial applications of ionic liquids covering the core processes and products, the practical implementation and technical challenges involved, and the potential future directions for Research and development. The individual chapters were written by leading scientists in the field from industry and academia to address specific processes and products that are or will be soon commercialized. Examples include the use of a chloroaluminate ionic liquid as a next-generation alkylation catalyst to a new class of capillary gas chromatography (GC) columns with stationary phases based on ionic liquids. Over the past twenty years, there has been a growing realization that ionic liquids have moved from being mere academic curiosities to having genuine applications in fields as wide-ranging as advanced materials, biotechnology, catalysis, pharmaceuticals, renewable fuels, and sustainable energy. There are many optimistic indications that ionic liquids are on their way to becoming a commercial success story. This first book on “Commercial Applications of Ionic Liquids” provides over 50 applications that are either at the pilot scale or have been commercialized, which indicates that an exciting new chapter in the field of ionic liquids is about to begin! KW - Ionic Liquids KW - Historical Developments KW - Advanced Materials PY - 2020 SN - 978-3-030-35245-5 DO - https://doi.org/10.1007/978-3-030-35245-5_1 SN - 2196-6990 SP - 3 EP - 29 PB - Springer CY - Cham AN - OPUS4-50453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Iqbal, S. A1 - Mady, A. H. A1 - Kim, Y.-I. A1 - Javed, U. A1 - Shafi, P. M. A1 - Nguyen, V. Q. A1 - Hussain, I. A1 - Tuma, Dirk A1 - Shim, J.-J. T1 - Self-templated hollow nanospheres of B-site engineered non-stoichiometric perovskite for supercapacitive energy storage via anion-intercalation mechanism N2 - The continual increase in energy demand and inconsistent supply have attracted attention towards sustainable energy storage/conversion devices, such as electrochemical capacitors with high energy densities and power densities. Perovskite oxides have received significant attention as anion-intercalation electrode materials for electrochemical capacitors. In this study, hollow nanospheres of nonstoichiometric cubic perovskite fluorides, KNi1-xCoxF3-delta (x = 0.2; delta = 0.33) (KNCF-0.2) have been synthesized using a localized Ostwald ripening. The electrochemical performance of the non-stoichiometric perovskite has been studied in an aqueous 3 M KOH electrolyte to categorically investigate the fluorine-vacancy-mediated charge storage capabilities. High capacities up to 198.55 mA h g-1 or 714.8 C g-1 (equivalent to 1435 F g-1) have been obtained through oxygen anion-intercalation mechanism (peroxide pathway, O-). The results have been validated using ICP (inductively coupled Plasma mass spectrometry) analysis and cyclic voltammetry. An asymmetric supercapacitor device has been fabricated by coupling KNCF-0.2 with activated carbon to deliver a high energy density of 40 W h kg-1 as well as excellent cycling stability of 98 % for 10,000 cycles. The special attributes of hollow-spherical, non-stoichiometric perovskite (KNCF-0.2) have exhibited immense promise for their usability as anion-intercalation type electrodes in supercapacitors. KW - Nanospheres KW - Perovskite KW - Supercapacitor PY - 2021 DO - https://doi.org/10.1016/j.jcis.2021.03.147 SN - 0021-9797 VL - 600 SP - 729 EP - 739 PB - Elsevier Inc. CY - Amsterdam AN - OPUS4-52873 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tuma, Dirk T1 - Comparison of multi-parameter Helmholtz and molecular-based EoS for the description of the density of a gravimetrically prepared LNG-type mixture N2 - The composition of liquefied natural gas (LNG) depends on the original gas composition and on the process of liquefaction and regasification. Regasified LNG typically has a lower percentage content of N2 and CH4 and a slightly higher percentage of higher alkanes than the original natural gas. The densities of this mixture, at four different temperatures, from 250 to 350 K and pressures up to 20 MPa, were determined using a high-accuracy single-sinker magnetic suspension densimeter at the UVa. The experimental densities were compared to those calculated by different multi-parameter equation of state (EoS) in terms of the reduced Helmholtz energy (AGA8-DC92, GERG-2008 and EoS-LNG), by a truncated virial EoS (SGERG-88), and by other EoS based on the perturbed-chain statistical associating fluid theory (PC-SAFT) and CP-PC-SAFT. T2 - 17th PPEPPD International Conference on Properties and Phase Equilibria for Product and Process Design CY - Bad Gögging, Germany DA - 11.05.2025 KW - LNG KW - High-pressure density KW - Reference equation of state PY - 2025 AN - OPUS4-63524 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tuma, Dirk A1 - Moreau, A. A1 - Polishuk, I. A1 - Segovia, J. J. A1 - Vega-Maza, D. A1 - Martín, M. C. T1 - Measurements and predictions of densities and viscosities in CO2 + hydrocarbon mixtures at high pressures and temperatures: CO2 + n-pentane and CO2 + n-hexane blends N2 - This work reports new experimental data on densities and viscosities of (CO2 + n-pentane) and (CO2 + n-hexane) mixtures at high pressures and temperatures. The densities were measured by a vibrating-tube densimeter with an expanded uncertainty (k = 2) smaller than 1.8 kg/m3 at six isotherms (from 273.15 K to 373.15 K), twelve pressures starting at 5 MPa up to 100 MPa, and at six CO2 molar compositions (from 0 to 0.6). The viscosities were measured by a vibrating-wire viscometer with the corresponding relative expanded uncertainty (k = 2) smaller than 0.016 at five isotherms (from 273.15 K to 373.15 K), twelve pressures (from 5 MPa up to 100 MPa), and at two CO2 molar compositions (0.1 and 0.3). The densities were fitted by the semiempirical Tammann-Tait equation for density data and the Vogel-Fulcher-Tammann (VFT) equation for viscosity data, respectively. The Groupe Européen de Recherches Gazières (GERG-2008) equation of state was also applied for modelling the densities. Over-all robustness and reliability of the Perturbed-Chain Statistical Association Fluid Theory (PC-SAFT) and its critical point-based modification (CP-PC-SAFT) were examined. Accuracies of the Modified Yarranton-Satyro (MYS) coupled with CP-PC-SAFT and the NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP 10) in predicting the viscosities were evaluated. KW - CO2 + n-alkanes KW - thermophysical properties KW - Perturbed-Chain Statistical Association Fluid Theory PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-555728 DO - https://doi.org/10.1016/j.molliq.2022.119518 SN - 0167-7322 VL - 360 SP - 1 EP - 15 PB - Elsevier CY - Amsterdam AN - OPUS4-55572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Safarov, J. A1 - Tuma, Dirk A1 - Müller, K. T1 - Thermophysical properties of the paramagnetic ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate over an extended range of temperature and pressure N2 - The paramagnetic ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate [BMIM][FeCl4] was subject to multiple high-precision thermophysical property measurements under both ambient and high pressure. Density rho(p0,T) / kg m-3 and speed of sound u(p0,T) / m s-1 data at ambient pressure were recorded at temperatures T = (278.15 to 343.16) K using a DSA 5000 M combined vibrating tube densimeter and speed of sound analyser with a standard uncertainty of delta rho(p0,T) = ±0.001 kg m-3 and delta u(p0,T) = ±0.1 m s-1, respectively. High-pressure volumetric (p,rho,T) data were measured on an Anton Paar DMA HPM vibrating tube densimeter at T = (273.16 to 413.15) K and at pressures up to p = 140 MPa with an estimated experimental relative combined average percentage deviation (APD) of delta rho(p,T) / rho(p,T) = ±(0.01 to 0.08) %. The specific isobaric heat capacity cp(p0,T) / J kg-1 K-1, a caloric property, was determined at T = (273.15 to 413.15) K with an uncertainty delta cp / cp = ±0.5 % using a Perkin Elmer Pyris 1 DSC differential scanning calorimeter. To gain knowledge of transport properties, the dynamic viscosity eta(p0,T) / mPa s at ambient pressure was recorded at T = (275.03 to 413.18) K by an Anton Paar SVM 3000 Stabinger viscometer and additionally an Anton Paar rheometer MCR 302 device with uncertainties of delta eta / eta = ±0.35 % and delta eta / eta = ±1 %, respectively. The obtained data were first correlated by empirical polynomial equations of state and further processed by the application of classic thermodynamic potentials to determine isothermal compressibility kappa T(p,T) / MPa-1, isobaric thermal expansivity alpha p(p,T) / K-1, thermal pressure coefficient gamma(p,T) / MPa K-1, internal pressure pint(p,T) / MPa, specific heat capacity at constant pressure cp(p,T) / J kg-1 K-1 and at constant volume cv(p,T) / J kg-1 K-1, the difference of isobaric and isochoric heat capacity (cp–cv)(p,T) / J kg-1 K-1, speed of sound u(p,T) / m s-1 and ultimately isentropic exponent kappa s(p,T). This work extends knowledge about the thermophysical properties of [BMIM][FeCl4] particularly to high temperatures and pressures. KW - Ionic liquid KW - Volumetric properties KW - Transport properties KW - Caloric properties PY - 2022 DO - https://doi.org/10.1016/j.molliq.2021.117939 SN - 0167-7322 VL - 346 SP - 1 EP - 16 PB - Elsevier CY - Amsterdam AN - OPUS4-54228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - von Preetzmann, N. A1 - Eckmann, P. A1 - Tuma, Dirk A1 - Richter, M. T1 - Thermodynamics of LNG N2 - Densities of eight gravimetrically prepared ternary and quaternary gas mixtures consisting of methane, ethane, propane, and partially nitrogen were investigated along the four isotherms of –250, –230, –210, and –190 °F at pressures of 350, 500, 650, and 1000 psig using a cryogenic single-sinker densimeter. The experimental densities were compared to densities calculated by various models, namely the EOS-LNG fundamental Helmholtz equation of state, the COSTALD correlation, the Lee-Kessler-Plöcker equation of state, and the Peng-Robinson equation of state. The best performance was shown by the EOS-LNG equation of state which is capable of predicting the liquid densities within the specified uncertainty of the model of 0.05 %. The other models, however, showed significant differences that disqualify for calculation within the p,T-region investigated of the gas mixtures. KW - Density measurement KW - Liquefied natural gas-like mixtures KW - Cryogenic state KW - Single-sinker densimeter KW - Equations of state PY - 2020 SP - 1 EP - 55 AN - OPUS4-50741 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tuma, Dirk A1 - Shafi, P. M. A1 - Mohapatra, D. A1 - Reddy, V. P. A1 - Dhakal, G. A1 - Kumar, D. R. A1 - Brousse, T. A1 - Shim, J.-J. T1 - Sr- and Fe-substituted LaMnO3 Perovskite: Fundamental insight and possible use in asymmetric hybrid supercapacitor N2 - The symmetry or structural stability of ABO3-type perovskite oxides depends largely on the size of ‘A’ and ‘B’ cations, which determines the material properties. The partial substitution of these cations may be used to tune these properties. The ionic sizes and valence states of the cations play an important role in improving the prop- erties of perovskite. In this study, the substitution of La3+ with Sr2+ with a larger ionic radius and Mn3+ with Fe3+ with a similar ionic radius favored both the crystal symmetry and the mixed ionic–electronic conductivity of the perovskite. Electrodes based on La0.7Sr0.3Mn0.5Fe0.5O3 (LSMFO55) exhibited a faradaic behavior with a specific capacity of 330 C g−1 (92 mAh g−1 ) at 12C rate, while this electrode maintained a capacity of 259 C g−1 at 240C (charge or discharge in 15 s). Additionally, exohedral carbon nano-onions (CNO) were introduced as a negative electrode to design an asymmetric hybrid supercapacitor (AHS) with a widened cell voltage. The use of CNO as a negative electrode in the AHS improved the rate capability drastically compared to the use of rGO. This device maintained a good energy density even at an extra-high charging rate (600C) owing to its outstanding rate capability. The high-rate performance of the LSMFO55//CNO AHS can be elucidated by successful fabrication with a mixed ionic–electronic conductive positive electrode and a CNO negative electrode. Tuning the electronic and ionic conductivities by cationic substitution and adopting an appropriate carbon-derived negative electrode (such as CNO) can provide a practical high-rate hybrid device using various perovskites. KW - Perovskite KW - Carbon nano-onion KW - Supercapacitor PY - 2022 DO - https://doi.org/10.1016/j.ensm.2021.11.028 SN - 2405-8297 VL - 45 SP - 119 EP - 129 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-54882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eshetie Kidie, A. A1 - Dhakal, G. A1 - Sahoo, S. A1 - Tuma, Dirk A1 - Shim, J.-J. T1 - Interlayer spacing-controlled carnation flower-like microstructure of nickel-manganese layered double hydroxide for enhancing hybrid supercapacitor performance N2 - Energy harvested from intermittent sources can be stored in supercapacitors for high-power delivery with long cycling stability. Binary layered double hydroxide (LDH) materials have great potential for hybrid supercapacitor applications owing to their mixed and tunable charges and layered structure. This study presents carnation flower-like, 3D micro-structured NiMn-LDH prepared by a facile single-step hydrothermal synthesis using hexamethylenetetramine to produce hydroxides. The 3D structure was assembled from ultrathin 2D NiMn-LDH nanosheets, and the largest interlayer spacing was obtained by optimizing synthesis parameters, such as Ni:Mn molar ratio and reaction temperature, ensuring a fast diffusion and thus the best energy storage performance. The optimized NiMn-LDH electrode delivered a high specific capacity of 612 C/g with an excellent rate capability of 67% at 20 A/g in a three-electrode test. An asymmetric device assembled using NiMn-LDH and reduced graphene oxide as positive and negative electrodes provided a high energy density of 60.0 Wh/kg and power density of 17.7 kW/kg with 90.4% capacity retention after 10,000 charge–discharge cycles. This superior result highlights the potential industrial applications, such as portable electronics and trams. KW - Supercapacitor KW - Hydrothermal synthesis KW - Interlayer spacing PY - 2024 DO - https://doi.org/10.1016/j.jiec.2023.12.032 SN - 1226-086X VL - 133 SP - 550 EP - 560 PB - Elsevier BV CY - Amsterdam AN - OPUS4-60472 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Soba, L. A1 - Tuma, Dirk T1 - Messung der Schallgeschwindigkeit in Neopentan bei Temperaturen von (263 bis 373) K und Drücken bis 20 MPa N2 - Alkan-Isomere haben signifikanten Einfluss als Spurenstoffe auf thermodynamische Eigenschaften von Erdgasgemischen. In Erdgas sind bis zu 0.35 mol-% Neopentan enthalten. Gemischmodelle basieren auf Reinstoffzustandsgleichungen der beteiligten Komponenten. Die hier untersuchte Schallgeschwindigkeit ist von besonderer Bedeutung für die Entwicklung hochgenauer Gleichungen. T2 - Thermodynamik-Kolloquium 2025 CY - Hamburg, Germany DA - 22.09.2025 KW - Neopentan KW - Schallgeschwindigkeit KW - Zustandsgleichung PY - 2025 AN - OPUS4-64226 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bulakhe, R. N. A1 - Nguyen, V. Q. A1 - Lee, Y. R. A1 - Zhang, H. A1 - Zhang, S. A1 - Shim, J.-J. A1 - Tuma, Dirk T1 - Chemically grown 3D copper hydroxide electrodes with different morphologies for high-performance asymmetric supercapacitors N2 - The present study investigated decoration of Cu(OH)₂ with different morphologies by copper precursors on 3D nickel foam. The Cu(OH)₂-A (nano flower)electrode showed an excellent capacitance of 1332 Fg⁻¹ at current density of 2 Ag⁻¹ compared to the Cu(OH)₂-C (nano ribbon, 1100 Fg⁻¹) and Cu(OH)₂-S (nano Long leaf, 1013 Fg⁻¹) electrodes. An asymmetric supercapacitor (ASC) was fabricated and showed a Maximum capacitance of 165 Fg⁻¹ at current density of 2 Ag⁻¹ with high energy density of 66.7 Wh kg⁻¹ and power density of 5698 W kg⁻¹ with excellent stability of 80 % after 10,000 cycles. KW - Copper hydroxide KW - Nickel foam KW - Supercapacitor PY - 2018 DO - https://doi.org/10.1016/j.jiec.2018.05.043 SN - 1226-086X SN - 1876-794X VL - 66 SP - 288 EP - 297 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-45930 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Safarov, J. A1 - Abdullayeva, G. A1 - Bashirov, M. A1 - Tuma, Dirk A1 - Bashirov, R. T1 - The ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate revisited: Solubility of carbon dioxide over an extended range of temperature and pressure N2 - Solubility data of carbon dioxide (CO2) in the ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate [EMIM][CH3SO3] at T= (273.15 to 413.15) K and pressures up to p= 5.0 MPa are reported. The solubility measurements were carried out using an isochoric method which operates in decrements of ΔT = 20 K within the investigated temperature range and at selected four different pressure steps ranging froma pressure p of around 5.0 MPa down to around 0.4 MPa. The solubility of CO2 in the ionic liquid monotonously decreases with increasing temperatures at a constant pressure. Within the p,T-range investigated, CO2 displayed a solubility in [EMIM] [CH3SO3] from a mole fraction x= 0.0160 mol·mol−1 and a corresponding molality m = 0.0791 mol·kg−1 at T = 413.15 K and p =0.432 MPa up to x = 0.4049 mol·mol−1 and m = 3.2982 mol·kg−1 at T = 293.15 K and p = 4.577 MPa. Henry's law constant was calculated from the solubility data reported here, and literature data were reviewed for comparison. Additionally, thermodynamic state properties that can be derived from Henry's law constant, such as the Gibbs energy of solvation ΔsolG, the enthalpy of solvation ΔsolH, the entropy of solvation ΔsolS, and the heat capacity of solvation ΔsolCp, were calculated. KW - Hydrophilic ionic liquid KW - Carbon dioxide KW - High-pressure solubility PY - 2021 DO - https://doi.org/10.1016/j.molliq.2021.115920 SN - 0167-7322 VL - 333 SP - 115920 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-52436 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tuma, Dirk A1 - Kharismadevi, D. A1 - Haldorai, Y. A1 - Nguyen, V. H. A1 - Shim, J.-J. T1 - Synthesis of graphene oxide-poly(2-hydroxyethylmethacrylate) composite by dispersion polymerization in supercritical CO2: adsorption behavior for the removal of organic dye N2 - The use of a biocompatible and thermoresponsive polymer, poly (2-hydroxyethyl methacrylate) (PHEMA) grafted onto the surface of graphene oxide (GO) as an adsorbent for the removal of a cationic dye (methylene blue [MB]) from an aqueous solution is examined in this work. GO–PHEMA forms a hydrogel in water thus overcoming the problem faced by carbon-based adsorbent materials during post-treatment (i.e., separation of adsorbent from the aqueous phase). The GO–PHEMA composite was synthesized using a green approach through dispersion polymerization in supercritical CO2. The successful preparation of this composite was confirmed by a series of characterization techniques. The adsorption behavior of the composite toward MB, such as the effect of the adsorbent dosage, pH, contact time, dye concentration, and recyclability was observed. In addition, the adsorption isotherm, kinetics and thermodynamics were investigated. According to the experimental data, the adsorption parameters were found to fit well into the Freundlich adsorption isotherm with a correlation coefficient of 0.975 and a maximum predicted adsorption capacity of 39.41 mg g−1 at 25 °C. The adsorption kinetics studies showed that the adsorption behavior followed a pseudo-second-order reaction. On the other hand, the thermodynamics studies showed that the adsorption of MB on GO–PHEMA composite followed spontaneous and endothermic adsorption process with an efficient adsorption temperature at 45 °C. The experimental results also showed that the GO–PHEMA composite could remove 99.8 % of the dye in 45 min. Therefore, GO–PHEMA composite is a favorable green adsorbent for environmental applications. KW - graphene oxide KW - poly (2-hydroxyethyl methacrylate) (PHEMA) KW - adsorption KW - composite materials PY - 2016 DO - https://doi.org/10.1080/09276440.2016.1169707 SN - 0927-6440 SN - 1568-5543 VL - 23 IS - 7 SP - 719 EP - 739 PB - Taylor & Francis CY - London, UK AN - OPUS4-36293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hernández-Gomez, R. A1 - Tuma, Dirk A1 - Segovia, J. J. A1 - Chamorro, C. R. T1 - Experimental determination of (p,rho,T) data for binary mixtures of methane and helium N2 - The basis for the development and evaluation of equations of state for mixtures is experimental data for several thermodynamic properties. The quality and the availability of experimental data limit the achievable accuracy of the equation. Referring to the fundamentals of GERG-2008 wide-range equation of state, no suitable data were available for many mixtures containing secondary natural gas components. This work provides accurate experimental (p,rho,T) data for two binary mixtures of methane with Helium (0.95 (amount-of-substance fraction) CH4 + 0.05 He and 0.90 CH4 + 0.10 He). Density measurements were performed at temperatures between (250 and 400) K and pressures up to 20 MPa by using a single-sinker densimeter with magnetic suspension coupling. Experimental data were compared with the corresponding densities calculated from the GERG-2008 and the AGA8-DC92 equations of state. Deviations from GERG-2008 were found within a 2% band for the (0.95 CH4 + 0.05 He) mixture but exceeded the 3% Limit for the (0.95 CH4 + 0.05 He) mixture. The highest deviations were observed at T = 250 K and pressures between (17 and 19) MPa. Values calculated from AGA8-DC92, however, deviated from the experimental data by only 0.1% at high pressures and exceeded the 0.2% limit only at temperatures of 300 K and above, for the (0.90 CH4 + 0.10 He) mixture. KW - Methane KW - Helium KW - Thermodynamic data KW - GERG-2008 equation of state PY - 2016 DO - https://doi.org/10.1016/j.jct.2015.12.006 SN - 0021-9614 VL - 96 SP - 1 EP - 11 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-35765 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Haloua, F. A1 - Foulon, E. A1 - El-Harti, E. A1 - Sarge, S. M. A1 - Rauch, J. A1 - Neagu, M. A1 - Brown, A. S. A1 - Tuma, Dirk T1 - Comparison of traceable methods for determining the calorific value of non-conventional fuel gases N2 - Energy-content measurements by direct methods (such as calorimetry) are used to validate the indirect method (from gas composition obtained by gas chromatography) which is generally adopted by grid operators for on-site gas control. A primary reference gas calorimeter and three field calorimeters were used for the first time to measure accurately the energy content of non-conventional gases (biogas and coal mine methane). The gas mixtures for this study were prepared by gravimetry and comprised three binary mixtures containing carbon dioxide and (up to 80 mol-%) methane, three ternary mixtures containing carbon dioxide, (up to 70 mol-%) methane and (up to 0.3 mol-%) hydrogen sulphide as well as a ten-component mixture with a methane content of approximately 64 mol-% which represents a typical coal mine methane. Associated uncertainty calculations were developed for each instrument and are presented here. Traceability of the measurements to the SI units is ensured in reference calorimetry, as calibration is accomplished by electrical simulation based on the Joule effect in order to obtain the heat capacity of the entire system. The results obtained with the four calorimeters are compared with each other and also with results calculated from the indirect method that is based on gas chromatography. Uncertainties (k = 2) between 0.07 and 0.49% for the reference gases were obtained with the reference calorimeter, while uncertainties for the field calorimeters range between 0.18 and 2.48% for the same mixtures. Compared to the usual standard deviation observed by gas chromatography for a multicomponent gas mixture of about 1%, it is demonstrated that the calorimetric method, although rarely used for non-conventional gases before, is appropriate for energy-content measurements of gases originating from renewable energy sources. KW - Non-conventional fuel gases KW - Gas calorimetry KW - Biogas KW - Calorific value PY - 2016 DO - https://doi.org/10.1016/j.ijthermalsci.2015.10.020 SN - 1290-0729 VL - 100 SP - 438 EP - 447 PB - Elsevier Masson SAS CY - Issy-les-Moulineaux AN - OPUS4-35766 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Tuma, Dirk A1 - Maurer, G. ED - Visser, A. E. ED - Bridges, N. J. ED - Rogers, R. D. T1 - Gas solubility in ionic liquids: Mixed gases in pure ionic liquids and single gases in binary liquid mixtures N2 - In the last two decades, the solubility of gases in ionic liquids has attracted a lot of attention. While at the beginning most publications dealt with the solubility of a single gas in a pure ionic liquid, recently the interest starts to shift to the – from an application-oriented point of view – more challenging area of the simultaneous solubility of several gases in an ionic liquid and/or the solubility of a single gas in solvent mixtures with ionic liquids. The current state of information on experimental data (and the phenomena encountered) in such systems is summarized and discussed. KW - Ionic liquids KW - Gas solubility KW - Phase equilibria PY - 2012 SN - 9780841227637 SN - 9780841227644 DO - https://doi.org/10.1021/bk-2012-1117.ch010 VL - 1117 SP - Chapter 10, 217 EP - 238 PB - American Chemical Society CY - Washington DC AN - OPUS4-35897 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oudwater, R. J. A1 - van Wijk, J. I. T. A1 - Persijn, S. A1 - Wessel, R. M. A1 - van der Veen, A. M. H. A1 - Mace, T. A1 - Sutour, C. A1 - Couette, J. A1 - Milton, M. A1 - Harling, A. A1 - Vargha, G. A1 - Uprichard, I. A1 - Haerri, H.-P. A1 - Niederhauser, B. A1 - Tuma, Dirk A1 - Maiwald, Michael A1 - Boissière, Claudia T1 - Final report on EURAMET QM-S8: Analysis of impurities in pure and balance gases used to prepare primary standard gas mixtures by the gravimetric method N2 - This project concerns the purity analysis of nitrogen as used in reference gas mixture preparation. This project was carried out without adding impurities to the gas used for this comparison, and is therefore more representative to evaluate the analysis of CO, CO2, CH4, O2, Ar and H2O impurities in high purity nitrogen. The analysis of the amount–of–substance fraction water was optional. Two 50 litre high purity nitrogen cylinders were purchased from a well-qualified supplier of specialty gases. The listed components were expected to be present in the pure nitrogen at the target levels as a result of the purification of the nitrogen. From the start of this comparison it was clear that the comparison may not lead to reference values for the constituents analysed. The results indicate that analyses of high purity gases are often limited by the limits of detection of analytical equipment used. The reports of the participating laboratories also indicate that there is no agreed method of determination of the uncertainty on a detection Limit value. The results provide useful information on the Performance of participants. For all analysed components there is reasonable agreement in results for LNE, VSL, Metas and NPL. For BAM only the Argon result is in agreement. KW - Gas analysis KW - Nitrogen KW - Purity analysis PY - 2013 DO - https://doi.org/10.1088/0026-1394/50/1A/08023 SN - 0026-1394 SN - 1681-7575 VL - 50 IS - 08023 SP - 1 EP - 58 PB - Institute of Physics Publishing CY - Bristol AN - OPUS4-35896 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tuma, Dirk T1 - Preparation and Analysis of Trace Compounds in Hydrogen in the ppm and Sub-ppm Region Relevant for Applications N2 - ISO 14687 defines threshold limits for expectable impurities in hydrogen that is assigned for use in polymer electrolyte membrane (PEM) fuel cells. This work describes the establishment of the traceability of some selected impurities by preparation and analysis of reference gases with the lowest possible uncertainty in composition. Primary reference gases were produced by the gravimetric method according to ISO 6142-1 and the analysis was carried out by operating measurement protocols according to ISO 12963 on two customized trace GC analysers. T2 - ANAKON 2023 CY - Vienna, Austria DA - 11.04.2023 KW - Hydrogen analysis KW - Gravimetric preparation KW - Gas chromatography PY - 2023 AN - OPUS4-57329 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 -