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 -