Enthalpies of Absorption and Solubility of Carbon Dioxide in Aqueous Polyamine Solutions

The enthalpies of absorption and solubility at T=298.15 K of carbon dioxide in aqueous solutions of bis-(3-dimethylaminopropyl)amine (CAS RN: [6711-48-4]) are reported in this paper. It was observed that the saturation loading of the CO₂ is α=2.9 mol CO₂/mol TMBPA, which is close to the theoretical value, α⁰=3 mol CO₂/mol TMBPA. The molar heat of absorption of CO₂ is independent of the polyamine concentration of the solutions and the amount of CO₂ absorbed and was calculated to be Δ_abs H _m=–44 (±2) kJ mol^–1 CO₂. This revised version was published online in July 2006 with corrections to the Cover Date.     

(Vapour + liquid) equilibria (VLE) of CO2 in aqueous solutions of 2-amino-2-methyl-1-propanol: New data and modelling using eNRTL-equation

This work presents new experimental results for carbon dioxide (CO₂) solubility in aqueous 2-amino-2-methyl-1-propanol (AMP) over the temperature range of (298 to 328) K and CO₂ partial pressure of about (0.4 to 1500) kPa. The concentrations of the aqueous AMP lie within the range of (2.2 to 4.9) mol · dm^?3. A thermodynamic model based on electrolyte non-random two-liquid (eNRTL) theory has been developed to correlate and predict the (vapour + liquid) equilibrium (VLE) of CO₂ in aqueous AMP. The model predictions have been in good agreement with the experimental data of CO₂ solubility in aqueous blends of this work as well as those reported in the literature. The current model can also predict speciation, heat of absorption, enthalpy of CO₂ loaded aqueous AMP, pH of the loaded solution, and AMP volatility.     

Beitrag zur Synthese des Hydroxylammoniumfluorids

Summary Hydroxylammonium fluoride was prepared in aqueous solution by the reaction of hydroxylamine with aqueous hydrogen fluoride. The solubility in water (148.7 g/100 g) and ethanol (0.146 g/100 g), the density (1.621±0.005 g/cm³) and the metling point (97.8±2 °C) of the compound have been determined. [NH₃OH]F crystallizes orthorombic, P_abc,a=6.490(1) Å,b=9.799(1) Å,c=13.519(2) Å.

     

Np(V) carbonates in solid state and aqueous solution

The solubility of NaNpO₂CO₃(s) in 0.1M perchlorate solution at 25°C in equilibrium with 1.0% CO₂/N₂ atmosphere has been investigated as a function of pH/lg [CO₃ ^2-]. The solid phase was found hexagonal with a=1008.1±0.3 pm and c=991.1±0.2 pm. A solubility product of lg Ksp(NaNpO₂CO₃)=–10.22±0.02 and a formation constant of the first Np(V) carbonato species of lg ß₀₁ = 4.52±0.02 was evaluated. For the dicarbonato species an upper limit of lg lg ß₀₂ < 6.6 was derived. Comparison of the present data with solubility values of Np(V) in equilibrium with 0.03% CO₂ partial pressure gave evidence that carbonato species are prevailing in solutions at both 1% and 0.03% CO₂ partial pressures.     

Effect of compressed CO2 on crystallization and melting behavior of isotactic polypropylene

Compressed gases such as CO₂ above their critical temperatures provide a highly tunable technique that has been shown to induce changes in phase behavior, crystallization kinetics and morphology of the polymers. Gas induced plasticization of the polymer matrix has been studied in a large number of polymers such as polystyrene, and poly(ethylene terephathalate). The knowledge of polymer–gas interactions is fundamental to the study of phenomena such as solubility and diffusivity of gases in polymers, dilation of polymers and in the development of applications such as foams and barrier materials.In this paper, we describe the interactions of compressed CO₂ with isotactic polypropylene (PP). Crystallization of various PPs in presence of compressed CO₂ was evaluated using a high pressure differential scanning calorimeter (HPDSC). CO₂ plasticized the polymer matrix and decreased the crystallization temperature, T_c by ∼8 °C for PP at a pressure of 650 psi CO₂. The decrease as a function of pressure was −0.173 °C/bar and did not change with the molecular architecture of PP. Both crystallization kinetics and melting behavior are evaluated.Since solubility and diffusivity are important thermodynamic parameters that establish the intrinsic gas transport characteristics in a polymer, solubility of CO₂ in PP was measured using a high-pressure electrobalance and compared with cross-linked polyethylene. At 50 °C, solubility followed Henry’s law and at a pressure of 200 psi about 1% CO₂ dissolved in PP. Similar solubility was achieved in PE at a pressure of 160 psi. Higher solubility of CO₂ in PE is attributed to its lower crystallinity and lower T_g, than PP. Diffusion coefficients were calculated from the sorption kinetics using a Fickian transport model. Diffusivity was independent of pressure and PE showed higher diffusivity than PP. Preliminary foaming studies carried out using a batch process indicate that both PP and PE can be foamed from the solid state to form microcellular foams. Cell size and cell density were ∼10 μm and 10⁸ cells/cm³, respectively in PE. Differences in morphology between the foams for these polymers are attributed to the differences in diffusivity.     

Electrochemical reduction of CO2 with high current density in a CO2 + methanol medium II. CO formation promoted by tetrabutylammonium cation

The cation of the supporting electrolyte was found to play an important role in the electrochemical reduction of highly concentrated CO₂ in a CO₂ + methanol medium. Electroreduction of CO₂ with tetrabutylammonium (TBA) salts yielded CO as the main product, while methyl formate was predominantly formed when lithium salts were used as supporting electrolytes. The latter supporting electrolytes showed a higher overvoltage than the former. When TBA salt was used, the reduction of CO₂ was catalysed by TBA ion to yield CO^−.₂. This intermediate may be stabilized by forming an ion pair, {TBA⁺---CO^−.₂}, or by being adsorbed on the electrode surface as CO^−._2ad. Then CO^−.₂ reacts with CO₂ to produce CO. The hydrophobic atmosphere at the electrode provided by TBA ion may be adequate for CO production. Lithium ion, on the other hand, suppressed the reduction of CO₂.     

Conversion of yttrium-aluminum garnet to soluble forms as a result of mechanochemical treatment

Summary The changes in the solubility and in the phase composition of yttrium-aluminum garnet (YAG) as a result of its mechanochemical treatment for 2 h in a planetary ball mill together with H₃BO₃ and Na₂CO₃ (mole ratio H₂BO₃/Na₂CO₃=4) in ratios (H₃BO₃+Na₂CO₃)/YAG=2,4, and 9 are studied. At a ratio of 9, the yield of yttrium in the water solution obtained upon treatment of the activated mixture at 90 °C (50 cm³ water/g sample) reaches 85%. Its content in the same solution is above 93% relatively to the sum Y+Al.

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Umwandlung von Yttrium-Aluminium-Granat in lösliche Formen durch mechanochemische Behandlung

Zusammenfassung Die Änderungen bezüglich Löslichkeit und Phasenzusammensetzung von Yttrium-Aluminium-Granat (YAG) als Ergebnis einer zweistündigen mechanochemischen Behandlung in einer Kugelmühle zusammen mit H₃BO₃ und Na₂CO₃ (Molverhältnis H₃BO₃/Na₂CO₃=4) bei (H₃BO₃+Na₂CO₃)/YAG-Verhältnissen von 2, 4 und 9 wurden untersucht. Bei einem Verhältnis von 9 erreicht die Ausbeute an Yttrium in der wäßrigen Lösung nach Behandlung der aktivierten Mischung bei 90 °C (50 cm³ H₂O pro Gramm) 85%. Relativ zur Summe Y+Al beträgt der Yttriumgehalt 93%.

     

Experimental study on equilibrium solubility (at low partial pressures), density, viscosity and corrosion rate of carbon dioxide in aqueous solutions of ascorbic acid

In this paper, ascorbic acid as a new carbon dioxide (CO₂) absorbent was investigated. The equilibrium solubility of CO₂ into 0.5, 1 and 1.5 mol dm⁻³ (M) aqueous ascorbic acid solutions were measured experimentally with a stirred batch reactor at total atmospheric pressure over the CO₂ partial pressure ranging from 0 to 45 kPa and temperatures between 298 and 313 K. The results of the gas solubility are presented as loading capacity (mol CO₂/mol ascorbic acid) as function of partial pressure of CO₂ for all experimental runs. Experimental results showed that solubility of CO₂ increases with increase in molar concentration of ascorbic acid solution at a given temperature and decreases with increase in temperature at a given concentration. The densities and viscosities of the ascorbic acid solutions were measured at the same conditions of the solubility measurement. Some corrosion rate tests were also performed on carbon steel at temperature of 308 K. It was observed that viscosity and corrosion rate increase when the molar concentration of ascorbic acid solution increases.     

Negative ion chemical ionization mass spectrometry of some nitroso compounds with CO2 as reagent gas

Summary Mass spectra of seven N-nitrosamines and five alkyl nitrites, the O-nitroso compounds, have been obtained by low pressure negative chemical ionization with CO₂ as reagent gas. Intense anions were observed at m/z M–32 for N-nitrosamines and at m/z M–30 for alkyl nitrites. Addition products were found at m/z M+12 and M+43 for N-nitrosamines and at m/z M+14 for alkyl nitrites. By using isotopically labeled CO₂, it could be shown that the anions at m/z M+12, M+14 and M+43 correspond to [M - H₂NO + CO₂ ^–, [M – NO + CO₂]^–, and [M – H + CO₂]^–, respectively.

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Negativionen-CI-Massenspektrometrie einiger Nitrosoverbindungen mit CO₂ als Reagensgas

Zusammenfassung Die Massenspektren von sieben N-Nitrosaminen und fünf Alkylnitriten (O-Nitrosoverbindungen) wurden durch negative chemische Ionisation bei niederem Druck mit CO₂ als Reagensgas erhalten. Intensive Anionen wurden bei m/z M–32 für N-Nitrosamine und bei m/z M–30 für Alkylnitrite beobachtet. Additionsprodukte fanden sich bei m/z M+12 und M+43 für N-Nitrosamine sowie bei m/z M+14 für Alkylnitrite. Mit Hilfe von Isotopen-markiertem CO₂ konnte gezeigt werden, daß die Anionen bei m/z M+12, M+14 und M+43, [M – H₂NO + CO₂]^–, [M – NO + CO₂]^– bzw. [M – H + CO₂]^– entsprechen.

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A full account of this work including the negative chemical ionization mass spectra obtained with other reagent gases will be submitted to the Journal of Mass Spectrometry.     

Thermodynamic Investigation of Phase Equilibria in Metal Carbonate–Water–Carbon Dioxide Systems

 Solubility measurements as a function of temperature have been shown to be a powerful tool for the determination of thermodynamic properties of sparingly-soluble transition metal carbonates. In contrast to calorimetric methods, such as solution calorimetry or drop calorimetry, the evaluation of solubility data avoids many systematic errors, yielding the enthalpy of solution at 298.15 K with an estimated uncertainty of ±3 kJ · mol⁻¹. A comprehensive set of thermodynamic data for otavite (CdCO₃), smithsonite (ZnCO₃), hydrozincite (Zn₅(OH)₆(CO₃)₂), malachite (Cu₂(OH)₂CO₃), azurite (Cu₃(OH)₂(CO₃)₂), and siderite (FeCO₃) was derived. Literature values for the standard enthalpy of formation of malachite and azurite were disproved by these solubility experiments, and revised values are recommended. In the case of siderite, data for the standard enthalpy of formation given by various data bases deviate from each other by more than 10 kJ · mol⁻¹ which can be attributed to a discrepancy in the auxiliary data for the Fe²⁺ ion. A critical evaluation of solubility data from various literature sources results in an optimized value for the standard enthalpy of formation for siderite. The Davies approximation, the specific ion-interaction theory, and the Pitzer concept are used for the extrapolation of the solubility constants to zero ionic strength in order to obtain standard thermodynamic properties valid at infinite dilution, T = 298.15 K, and p = 10⁵ Pa. The application of these electrolyte models to both homogeneous and heterogeneous (solid-solute) equilibria in aqueous solution is reviewed.     

Synthese und Strukturuntersuchung von Zn3Ta2O8

Zn₃Ta₂O₈ was prepared by high temperature solid state reaction (CO₂-Lasertechnique). X-ray investigations of single crystals yield monoclinic symmetry (a=9.499;b=8.411;c=8.881 Å; =116.03°, space group C _2h ⁶ —C2/c). There is no relationship between Zn₃Ta₂O₈ and Zn₃Nb₂O₈. Zn₃Ta₂O₈ shows a characteristic structure type with octahedral coordination of Ta⁵⁺ and tetrahedral coordination of Zn²⁺.

     

The solubility of CO2 and N2O in olive oil

The solubility of CO₂ and N₂O in olive oil has been measured at temperatures of about 298, 310, and 323 K with a gravimetric microbalance under pressures up to 2 MPa. The molecular weight of olive oil has been analyzed and found to be about 882 g mol⁻¹ as a mixed oil compound. The observed solubility data have been correlated with a cubic equation of state (EOS) model. N₂O has a larger solubility than CO₂ in olive oil based on either the mole or mass fraction. The present results clarify some ambiguities from the previous N₂O solubility data in the literature.     

Activation energy of thermal decomposition of SmC2O4Cl to SmOCl,CO and CO2

An activation energy of E_a=213.73 kJ mol^–1 has been determined for the thermal decomposition of SmC₂O₄Cl to SmOCl, CO and CO₂. The result is predictable on the basis of the Kahwa-Mulokozi expression + for the activation energy and its extended interpretation.

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Zusammenfassung Für den thermischen Zerfall von SmC₂O₄Cl in SmOCl, CO und CO₂ wurde eine Aktivierungsenergie vonE _a=213.73 kJ.mol^–1 ermittelt. Dieses Ergebnis kann auf der Basis der Kahwa-Mulokozi-Beziehung für die Aktivierungsenergie und ihrer erweiterten Interpretation vorhergesagt werden.

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On study leave from the university of sokoto, Nigeria.     

Study of the solubility of CO2, H2S and their mixture in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate: Experimental and modelling

New experimental results are presented for the solubility of carbon dioxide, hydrogen sulfide in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate ([C₈mim][PF₆]) at temperatures range from (303.15 to 353.15) K and pressures up to about 2 MPa. The solubility of the mixture of CO₂/H₂S in [C₈mim][PF₆] under various feed compositions were also measured at temperatures of (303.15, 323.15 and 343.15) K and the pressure up to 1 MPa. The solubility of carbon dioxide and hydrogen sulfide increased with increasing pressure and decreased with increasing temperature and the solubility of H₂S is about three times that of CO₂ in the particular ionic liquid studied. The measured data were correlated using extended Henry’s law included Pitzer’s virial expansion for the excess Gibbs energy, and the generic Redlich–Kwong cubic equation of state proposed for gas/ionic liquid systems. The correlations from the two models show quite good consistency with the experimental data for CO₂/IL and H₂S/IL binary mixtures within experimental uncertainties. For CO₂/H₂S/IL ternary mixtures, the RK model shows better correlation with the experimental values. We also studied the effect of cation alkyl chain length on the CO₂ and H₂S solubility by comparison of the experimental data of this study with those of previous reports. As the cation alkyl chain length became longer, the solubility of CO₂ and H₂S increased in the ionic liquid. Additionally, the influence of the anion on the solubility is studied by comparing the solubility of CO₂ and H₂S in [C₈mim][PF₆] with those in [C₈mim][Tf₂N]. As a result, CO₂ and H₂S have higher solubility in the IL with [Tf₂N]⁻ as the anion.     

Equilibrium solubility of carbon dioxide in the amine solvent system of (triethanolamine + piperazine + water)

In this study, a new set of data for the equilibrium solubility of carbon dioxide in the amine solvent system that consists of triethanolamine (TEA), piperazine (PZ), and water is presented. Equilibrium solubility values were obtained at T = (313.2, 333.2, and 353.2) K and pressures up to 153 kPa using the vapour-recirculation equilibrium cell. The TEA concentrations in the considered ternary (solvent) mixture were (2 and 3) kmol · m^?3 and those of PZ’s were (0.5, 1.0, and 1.5) kmol · m^?3. The solubility data (CO₂ loading in the amine solution) obtained were correlated as a function of CO₂ partial pressure, system temperature, and amine composition via the modified Kent–Eisenberg model. Results showed that the model applied is generally satisfactory in representing the CO₂ absorption into mixed aqueous solutions of TEA and PZ.     

The formation of formic acid upon low-temperature condensation of CO2−H2 and CO−H2O gas mixtures dissociated in electric discharge

The formation of formic acid in the low-temperature condensation of CO₂−H₂ and CO−H₂O gas mixtures dissociated in electric discharge was investigated. The gas-phase concentrations of H^., O^., OH^., and O₂ were measured downstream a microwave discharge in a CO₂−H₂ mixture. Low-temperature (77 K) condensates formed from CO₂−H₂ and CO−H₂O mixtures were studied by ESR. The formation of formic acid in the CO₂−H₂ and CO−H₂O systems was found to be due to the reactions of H^., CO, O^., and O₂ on the condensate surface. A single mechanism of the formation of formic acid in the CO₂−H₂ and CO−H₂O systems was proposed.     

Über den Weg der nicht-mitochondrialen,Jodacetat-aktivierten Oxydation des Glucose-C-6 in Ascites-Tumor-Zellen

Zusammenfassung Der zytoplasmatische, Mitochondrien-freie Überstand eines Homogenates von Ehrlich-Lettré-Ascites-Carcinom-Zellen vermag Glucose-C-6 in CO₂ überzuführen. Die Reaktion wird durch Jodacetat stark aktiviert. Die Jodacetat-aktivierte Oxydation von Glucose-C-6 zu CO₂ zeigt eine ähnliche Abhängigkeit von den CoenzymenNAD ⁺ undNADP ⁺ wie die Oxydation von Glucose-C-1 zu CO₂. Die Jodacetat-aktivierte Oxydation von Glucose-C-6 wird durch einige unmarkierte Metabolite des Glucuronsäure-Cyclus geringfügig, durch 6-Phosphogluconat, einen Metaboliten des Pentosephosphat-Cyclus, jedoch stark herabgesetzt.Die Resultate sprechen dafür, daß (in Anwesenheit von Jodacetat) C-6-der zugesetzten Glucose in die Position 1 des Glucose-6-P übergeführt, und dann weiter über den Pentosephosphat-Cyclus zu CO₂ oxydiert wird.

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The cytoplasmatic mitochondria-free supernatant of a homogenate of Ehrlich-Lettré-ascites-carcinoma cells is capable of converting glucose-C-6 to CO₂. The reaction is strongly activated by iodoacetate. The iodoacetate-activated oxidation of glucose-C-6 to CO₂ depends in a similar way on the coenzymesNAD ⁺ and NADP⁺ as does the oxidation of glucose-C-1 to CO₂. The iodoacetate-activated oxidation of glucose-C-6 is negligibly decreased by the addition of some inactive metabolites of the glucuronic acid cycle, but strongly decreased by 6-phosphogluconate, a metabolite of the pentose phosphate cycle.The results suggest that, in the presence of iodoacetate, C-6 of the added glucose is transferred to position 1 of the glucose-6-P and then further oxidized to CO₂ via the pentose phosphate cycle.

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Abkürzungen ATP Adenosin-5-triphosphat - EDTA Äthylen-diamintetraacetat - NAD nicotinamidadenindinukleotid - NADP Nicotinamidadenindinukleotidphosphat - UDP Uridin 5-diphosphat     

Thermodynamic Investigation of Phase Equilibria in Metal Carbonate–Water–Carbon Dioxide Systems

Summary.  Solubility measurements as a function of temperature have been shown to be a powerful tool for the determination of thermodynamic properties of sparingly-soluble transition metal carbonates. In contrast to calorimetric methods, such as solution calorimetry or drop calorimetry, the evaluation of solubility data avoids many systematic errors, yielding the enthalpy of solution at 298.15 K with an estimated uncertainty of ±3 kJ · mol⁻¹. A comprehensive set of thermodynamic data for otavite (CdCO₃), smithsonite (ZnCO₃), hydrozincite (Zn₅(OH)₆(CO₃)₂), malachite (Cu₂(OH)₂CO₃), azurite (Cu₃(OH)₂(CO₃)₂), and siderite (FeCO₃) was derived. Literature values for the standard enthalpy of formation of malachite and azurite were disproved by these solubility experiments, and revised values are recommended. In the case of siderite, data for the standard enthalpy of formation given by various data bases deviate from each other by more than 10 kJ · mol⁻¹ which can be attributed to a discrepancy in the auxiliary data for the Fe²⁺ ion. A critical evaluation of solubility data from various literature sources results in an optimized value for the standard enthalpy of formation for siderite. The Davies approximation, the specific ion-interaction theory, and the Pitzer concept are used for the extrapolation of the solubility constants to zero ionic strength in order to obtain standard thermodynamic properties valid at infinite dilution, T = 298.15 K, and p = 10⁵ Pa. The application of these electrolyte models to both homogeneous and heterogeneous (solid-solute) equilibria in aqueous solution is reviewed. Received June 26, 2001. Accepted July 2, 2001     

Chromium(III) Hydroxide Solubility in the Aqueous K+-H+-OH?-CO2-HCO 3? -CO 32? -H2O System: A?Thermodynamic Model

Chromium(III)-carbonate reactions are expected to be important in managing high-level radioactive wastes. Extensive studies on the solubility of amorphous Cr(III) hydroxide solid in a wide range of pH (3–13) at two different fixed partial pressures of CO₂(g) (0.003 or 0.03 atm.), and as functions of K₂CO₃ concentrations (0.01 to 5.8 mol⋅kg⁻¹) in the presence of 0.01 mol⋅dm⁻³ KOH and KHCO₃ concentrations (0.001 to 0.826 mol⋅kg⁻¹) at room temperature (22±2 °C) were carried out to obtain reliable thermodynamic data for important Cr(III)-carbonate reactions. A combination of techniques (XRD, XANES, EXAFS, UV-Vis-NIR spectroscopy, thermodynamic analyses of solubility data, and quantum mechanical calculations) was used to characterize the solid and aqueous species. The Pitzer ion-interaction approach was used to interpret the solubility data. Only two aqueous species [Cr(OH)(CO₃)₂²⁻ and Cr(OH)₄CO₃³⁻] are required to explain Cr(III)-carbonate reactions in a wide range of pH, CO₂(g) partial pressures, and bicarbonate and carbonate concentrations. Calculations based on density functional theory support the existence of these species. The log ₁₀ K° values of reactions involving these species [{Cr(OH)₃(am) + 2CO₂(g)⇌Cr(OH)(CO₃)₂²⁻+2H⁺} and {Cr(OH)₃(am) + OH⁻+CO₃²⁻ ⇌Cr(OH)₄CO₃³⁻}] were found to be −(19.07±0.41) and −(4.19±0.19), respectively. No other data on any Cr(III)-carbonato complexes are available for comparisons.     

Solubility of Carbon Dioxide in Aqueous Mixtures of DIPA + MDEA and DIPA + PZ Solutions

The new data for solubility of carbon dioxide are reported in mixed solvents containing (2.00 to 2.50 kmol/m³) Diisopropanolamine (DIPA), (0.86 to 1.36) kmol/m³) Piperazine (PZ), (0.86 to 1.36) kmol/m³) N‐methyldiethanolamine (MDEA) and water, keeping the amine total concentration in the aqueous solution at 3.36 kmol/m³ for temperatures from (40 to 70) °C and CO₂ partial pressures in the range of (30 to 5000) kPa. Experimental solubility results were represented by the mole ratio of CO₂ per total amine in the liquid mixture. Results show that at a given partial pressure of CO₂ the solubility of CO₂ in the DIPA solutions is lower than solubility in MDEA or PZ solutions and the CO₂ loading increased with decreasing temperature and increasing CO₂ partial pressure.