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  • 更新日期:2020-01-26
  • Experimental densities and derived thermodynamic properties of pure p-cymene, α-pinene, limonene and citral under high pressure conditions
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-24
    JovanaIlić Pajić; Gorica Ivaniš; Ivona Radović; Aleksandar Grujić; Jasna Stajić-Trošić; Mirko Stijepović; Mirjana Kijevčanin

    In order to reduce negative influence of fossil fuels on environment, use of various renewable resources is highly promoted. Terpenes, naturally occurring in plants, can be added to petroleum fuel as its substitute up to a certain share. Thermodynamic properties of a fuel under high pressure and moderate temperature conditions are of significant importance for engine efficiency. This work reports density measurements of pure p-cymene, α-pinene, limonene and citral at temperatures (293.15-413.15) K and pressures (0.1-60) MPa, applying an Anton Paar DMA HP measuring cell. Density data were fitted by modified Tammann-Tait equation where the absolute average percentage deviation between measured and calculated densities was about 0.010%. The obtained parameters were used to estimate the isothermal compressibility, the isobaric thermal expansion coefficient, the internal pressure, and the difference between specific heat capacity at constant pressure and at constant volume. For examined compounds, all thermodynamic properties, except the internal pressure, decrease with pressure rise along an isotherm and increase as temperature increases at a constant pressure. The intersection point of isotherms for the isobaric thermal expansion coefficient for pure citral was registered at pressure 47 MPa, while for other analyzed terpenes the intersection point is above 60MPa, outside the measurements pressure range.

    更新日期:2020-01-24
  • 更新日期:2020-01-24
  • 更新日期:2020-01-24
  • Measurement and modelling of water activities of the {CuSO4 + poly(ethylene glycol) + H2O} system in the temperature range from 303.15 to 333.15 K
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-23
    Yecid P. Jimenez; Francisca J. Justel

    In this work, thermodynamic properties of unsaturated solutions of (CuSO4 + PEG 2000 + H2O) system at (303.15, 313.15, 323.15 and 333.15) K were studied. The concentration range of the solutions was from 0.01 to 0.05 mass fraction of CuSO4 and from 0.15 to 0.3 mass fraction of poly(ethylene glycol) with an average molar mass of 2000 g/mol. Water activities were correlated with the modified Pitzer model, obtaining a good agreement between the experimental and correlated data. In addition, water activities predictions for the (CuSO4 + PEG 4000 + H2O) and (CuSO4 + PEG 2000 + H2O) systems were performed with the modified Pitzer and extended UNIQUAC models, respectively, showing that both thermodynamic models operate independently of the molar mass of the polymer used. The effect of the cations on the water activities of different (Salt + PEG 4000) systems was evaluated, showing a close relation with the Molar Gibbs Energies of Hydration of the respective cations. The salting effect and Gibbs Energy change (ΔG) of different ternary systems showed that a salting-out effect occurs in all the studied systems.

    更新日期:2020-01-23
  • 3-Methyl-6-nitroindazole in some aqueous co-solvent mixtures: Solubility determination, preferential solvation and solvent effect analysis
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-23
    Wanxin Li; Ali Farajtabar; Rong Xing; Yiting Zhu; Hongkun Zhao; Rongguan Lv
    更新日期:2020-01-23
  • 更新日期:2020-01-23
  • Enthalpy measurements and thermodynamic properties of M2TeO6(s) (M = Eu,Dy)
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-22
    R. Kandan; Ashish Jain; P. Venkatesh; B. Prabhakara Reddy

    Heat content or enthalpy measurements were conducted on Eu2TeO6(s) and Dy2TeO6(s) by employing the method of inverse drop calorimetry using a high temperature differential calorimeter between about 670 and 1270 K. The measured enthalpy increments with temperature are given as: HT0-H2980 /J mol-1 < Eu2TeO6 ˃ =229.494T+1.199x10-2T2+18.197x105T-1-75592(670 ≤ T (K) ≤ 1270) and HT0-H2980 / J mol-1 < Dy2TeO6 ˃ = 217.942T +1.103x10-2T 2 +14.896 x105T-1 -70957(672 ≤ T (K) ≤ 1268) .Using the standard Gibb’s energies of formation of M2TeO6(s) (M = Eu, Dy) obtained from vapour pressure measurement as reported by us in previous work (Asish Jain et.al. in J Therm Anal Caloim (2015) 119:689-693) and Gibb’s energy functions computed from the enthalpy measurement of M2TeO6(s) (M = Eu,Dy) of the present study, the mean value of ΔfH298o has been deduced. The mean value of ΔfH298o < Eu2TeO6 ˃ and < Dy2TeO6 ˃ were found to be - 2260 ± 0.2 and - 2474 ± 0.17 kJ mol-1 respectively. The high temperature enthalpy increments on Eu2TeO6(s) and Dy2TeO6(s) are being reported for the first time.

    更新日期:2020-01-22
  • Phase behavior of tetramethylurea + MCl (M = Na, K, Rb, Cs) + H2O systems at 288.2, 298.2 and 308.2 K
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-21
    Xiaoyue Cao; Yahui Chang; Shuni Li; Quanguo Zhai; Yucheng Jiang; Mancheng Hu
    更新日期:2020-01-22
  • Thermodynamic investigation of the Ruddlesden-Popper phase Sr3Fe2O7
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-20
    A.V. Knyazev; Yu.V. Alekseeva; N.N. Smirnova; O.V. Krasheninnikova; A.V. Markin; E.V. Syrov; E.V. Elipasheva; L.V. Smirnova
    更新日期:2020-01-21
  • Thermochemistry of di-substituted benzenes: nitro- and dimethylamino benzaldehydes
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-19
    Riko Siewert; Aizat A. Samatov; Ruslan N. Nagrimanov; Sergey P. Verevkin

    Standard molar enthalpies of vaporization/sublimation (check for euro journal) of nitro and amino-substituted benzaldehydes were obtained from the temperature dependence of vapour pressure measured by the transpiration method. Enthalpies of fusion of these compounds were measured by using DSC. Solution enthalpies of nitro and amino-substituted benzaldehydes were measured by using a solution calorimeter. Available from literature primary experimental results on temperature dependences of vapour pressures have been collected and they have been treated uniformly in order to derive vaporization/sublimation enthalpies at the reference temperature 298.15 K. Standard molar enthalpies of formation of crystalline isomers of nitro-benzaldehydes were measured by using combustion calorimetry. Gas phase molar enthalpies of formation of substituted benzaldehydes were calculated by the high-level quantum-chemical G4 method and they were used for evaluation of available experimental results. A set of thermodynamic properties of substituted benzaldehydes was recommended as reliable reference properties for thermochemical calculations. Simple group-additivity procedures were developed for estimation of vaporization enthalpies, gas-phase, and liquid-phase enthalpies of formation of substituted benzenes.

    更新日期:2020-01-21
  • Molecular mechanism of the clathrate cage formation in structure-Ⅱ cyclopentane hydrate: an ab initio study
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-18
    Jing Wen; Yongsheng Zhang; Wanru Zhou; Yuanyuan Fu; Weilong Zhao; Wei Sheng
    更新日期:2020-01-21
  • Thermodynamic characteristics of Li2MoO4, Li2W0.85Mo0.15O4 single crystals and stability direction for alkali molybdates
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-14
    N.I. Matskevich; V.N. Shlegel; A.L. Sednev; A.N. Semerikova; V.P. Zaitsev; V.A. Kuznetsov; A.Yu. Novikov; A.Yu. Zuev

    Single crystals of Li2MoO4 and Li2W0.85Mo0.15O4, as perspective materials to search for neutrino-less double beta decay, have been grown by low-temperature-gradient Czochralski technique (LTG CZ). The standard formation enthalpies for single crystals of Li2MoO4 and Li2W0.85Mo0.15O4 have been determined by two methods: (i) solution calorimetry in KOH (ΔfH0 (Li2MoO4, s, 298.15K) = −(1521.9 ± 1.9) kJ mol-1) and (ii) high-temperature reaction calorimetry in sodium molybdate melt (3Na2O · 4MoO3) (ΔfH0 (Li2MoO4, s, 298.15K) = −(1529.1 ± 7.3) kJ mol-1; ΔfH0 (Li2W0.85Mo0.15O4, s, 298.15K) = −(1597.8 ± 4.3) kJ mol-1). The measured solution enthalpies of Li2CO3, MoO3, WO3, Li2MoO4, Li2W0.85Mo0.15O4 in 3Na2O · 4MoO3 melt and solution enthalpies of Li2CO3, MoO3, Li2MoO4 in KOH have been used to calculateΔfH0. The thermodynamic stability of A2MoO4 (A = Li, Na, K, Rb, Cs) with respect to simple oxides mixture has been determined. It has been found that the relative thermodynamic stability is increased from Li2MoO4 up to Cs2MoO4. This fact seems to be important from practical point of view. The lattice enthalpies for A2MoO4 compounds have been calculated using the Born-Haber cycle. The dependences of lattice enthalpies for A2MoO4 on structural parameters have been constructed, which allow one to predict the thermodynamics for compounds not investigated.

    更新日期:2020-01-14
  • Liquid organic hydrogen carriers: hydrogen storage by di-phenyl ether derivatives: an experimental and theoretical study
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-13
    Sergey P. Verevkin; Andrey A. Pimerzin; Li-Xian Sun

    The liquid organic hydrogen carriers (LOHCs) are promising materials for hydrogen storage. The standard molar enthalpies of formation, ΔfHmo(liq/cr) of diphenyl ether substituted with amino substituents were measured by the high-precision combustion calorimetry. Enthalpies of vaporisation/sublimation Δl,crgHmo(298.15 K) of these compounds were obtained by the transpiration method. Enthalpies of fusion were measured by DSC. Gas-phase enthalpies of formation ΔfHmo(g, 298.15 K) of substituted diphenyl ethers calculated by the G4 method were in an excellent agreement with the experimental results. Enthalpies of the hydrogenation/dehydrogenation reactions of diphenyl ether derivatives were estimated and compared with the data available for other potential LOHC. A set of thermodynamic properties of diphenyl ether derivatives of benchmark quality was recommended for thermochemical calculations. Equilibrium temperatures of hydrogenation/dehydrogenation processes were calculated and compared with those of benzene derivatives. Due to the high hydrogen storage capacity, as well as very low volatility, these compounds could be considered as seminal candidates for LOHC.

    更新日期:2020-01-13
  • Thermophysical properties of switchable-hydrophilicity solvent systems: N,N-Dipropyl-1-propanamine, water and carbon dioxide
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-11
    Jian Wang; Xin Yuan; Hongkun Zhao; Yaqiong Wang; Xuedong Zhu; Xuhong Guo; Jean-Noël Jaubert

    Measurements of density, viscosity, refractive index and conductivity of a switchable hydrophilicity solvent (SHS) system (N,N-dipropyl-1-propanamine (TPA), water, and carbon dioxide) have been carried at (283.15-308.15) K and 0.1 MPa. The derived parameters, such as apparent molar volume of solute, limiting apparent molar volume of solute, Masson’s coefficient SV, molar refraction and limiting molar conductivity, were obtained using the density, refractive index and conductivity results. Viscosity results are used to calculate the Jones-Dole viscosity B-coefficient, free energy of activation of the solute and solvent, activation enthalpy, and activation entropy. A detailed insight into the physicochemical interactions occurring among solute and solvent molecules along with the structure-making/structure-breaking tendency has been retrieved through the perusal of these calculated parameters.

    更新日期:2020-01-13
  • Measurement and correlation of the (p, ρ, T) behaviour of liquid ethylene glycol at temperatures from (283.3 to 393.1) K and pressures up to 100.1 MPa
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-11
    Xiaoxian Yang; Catherine C. Sampson; Ophelia Frotscher; Markus Richter

    The (p, ρ, T) behaviour of ethylene glycol was investigated over the temperature range from T = (283.3 to 393.1) K at pressures from p = (4.8 to 100.1) MPa utilizing a high-pressure vibrating-tube densimeter. This work extends the current data situation for the density of ethylene glycol with respect to temperature and pressure ranges. Four mathematical models for the vibrating-tube densimeter were used to calculate density from the measured oscillation period, and the influence of the model on the resulting density was investigated. The combined expanded uncertainty (k = 2) of the experimental densities was estimated to be 1.57 kg∙m–3. The new experimental data were regressed to a Schilling-type correlation equation with its exponent parameters being the same as those for propylene glycol that we studied previously; in a second step, the correlation equation was optimized using an “artificial intelligence powered” modeling tool. With this optimization, the number of the parameters was reduced, while the goodness of the fitting was slightly improved. The combined expanded uncertainties (k = 2) of the correlation equations were estimated to be 1.59 kg∙m–3 in the investigated (p,T) range. Carefully selected experimental data from literature generally agree with the correlation equations within the uncertainty of the equation.

    更新日期:2020-01-13
  • Heat capacity and thermodynamic properties of alkali and alkali-earth borohydrides
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-10
    Erika M. Dematteis; Steffen R. Jensen; Torben R. Jensen; Marcello Baricco

    In this work, the above room temperature heat capacity for different polymorphs of alkali and alkali-earth (i.e. Na, K, Rb, Cs, Mg, Ca) borohydrides has been measured by DSC as a function of temperature. The above room temperature measured Cp values have been compared with available extrapolated literature data, and they have been modelled as a function of temperature according to the Calphad method. The variations of Cp values for different polymorphs were studied in details and they have been related to the corresponding crystal structures, considering the mobility of the BH4- group. From the whole set of assessed thermodynamic data, possible correlations with dynamics and structural properties have been estimated.

    更新日期:2020-01-11
  • 更新日期:2020-01-11
  • 更新日期:2020-01-09
  • Excess molar volumes of cyclohexanone with n-, sec-, or tert-butylbenzene: Application of the PFP theory and Graph-theoretical approach
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-08
    Dongwei Wei; Mengying Li; Jing Ma; Baohe Wang

    Excess molar volumes, VE, for the binary mixtures of cyclohexanone with n-, sec-, or tert-butylbenzene were measured over the entire composition range at (298.15, 303.15, 308.15 and 313.15) K and 0.1 MPa, by means of a vibrating-tube densimeter. VE data are sigmoid shape for the studied mixtures of cyclohexanone + n-butylbenzene (with negative VE values at lower mole fractions of cyclohexanone) and negative for the mixtures of cyclohexanone + sec-butylbenzene, and cyclohexanone + tert-butylbenzene over the whole composition range. The absolute values of excess equimolar volumes vary in the order: tert-butylbenzene > sec-butylbenzene > n-butylbenzene. The VE in the studied systems increase as the rising temperature. The Redlich-Kister equation was applied to fit the experimental data. Using the coefficients of the Redlich–Kister equation, excess partial molar volumes at infinite dilution, V¯iE,∞ were calculated for the three binary systems. Molecular non-bond energy, E for binary mixtures at the mole fraction of 0.5 and temperature of 298.15 K also were calculated by the MD simulations. The Prigogine–Flory–Patterson theory and Graph-theoretical approach were examined for the suitability by correlating experimental VE data with compositions.

    更新日期:2020-01-09
  • Heat capacity and thermodynamic functions of TiO2(H)
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-08
    Tao Feng; Liping Li; Quan Shi; Yuelan Zhang; Guangshe Li
    更新日期:2020-01-08
  • Expanding thermodynamic databases using the thermodynamic difference rule (TDR). Exemplified by an application to retrieve new thermodynamic data for thorium compounds
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-07
    H. Donald Brooke Jenkins

    This paper explores the thermochemistry of thorium compounds, in particular their hydrates MpXq.nH2O and their corresponding parents, MpXq. By taking currently available thermochemical data from the literature, we use the Thermodynamic Difference Rule (TDR) to illustrate how we can retrieve new (previously missing) data without necessitating calorimetric investigation. Moreover the results obtained are likely to have a level of accuracy and precision equal to that obtained using traditional calorimetric methods yet avoiding the attendant radiochemical procedures required for safe handling of these materials. In this way, commencing with an incomplete table containing only 42 entries out of a possible 84 (i.e. 50 %), as many as 22 (i.e. 26 %) new items of data can be deduced just by using the TDR so making the Table now 76 % complete. By this purely computational route (which requires use of a simple EXCEL spreadsheet or even just a hand calculator) which can be used by non-experts quickly and easily, the new data can be estimated and the database so expanded. The TDR Rule can also be used to validate already available, existing data. This approach represents a new and improved method of investigation of standard thermochemical data and can be used in all branches of science, not necessarily areas involving the handling of radioactive materials, moisture or air sensitive but any material – a truly universal rule

    更新日期:2020-01-07
  • Determination and correlation of ternary isobaric vapour-liquid equilibrium data of (dimethyl succinate+ dimethyl glutarate+ dimethyl adipate) at 2, 5and 8kPa
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2020-01-03
    Chunli Zhi; Yang Tang; Jinru Wan; Xingming Liu; Honglin Chen; Xunqiu Wang

    Isobaric vapour-liquid equilibrium data of {dimethyl succinate (DMS) + dimethyl glutarate (DMG) + dimethyl adipate (DMA)} ternary system was measured at 2 kPa, 5 kPa and 8 kPa with a dynamic recirculating apparatus and the temperature ranged from 364.46 to 403.55K. The experimental data was correlated with NRTL, Wilson and Uniquac models. The results showed that the maximum value of the root mean square deviation of the vapour phase mole fraction of the ternary system correlated by the three models is 0.0083, 0.0076 and 0.0084, respectively. The vapour-liquid equilibrium data of the ternary system was predicted by the interaction parameters of NRTL, Wilson and the Uniquac models in the literature. The results showed that the maximum value of the root mean square deviation of the vapour phase mole fraction of the ternary system predicted by the three models is 0.0547, 0.0471, and 0.0498, respectively. The deviation between the experimental value and the regression value or the predicted value was small, and both met the needs of design calculation of the engineering separation. The results obtained from the regression of experimental values are significantly better.

    更新日期:2020-01-04
  • 更新日期:2020-01-02
  • 更新日期:2020-01-02
  • 更新日期:2019-12-31
  • Surface tension of binary mixtures composed of N, N-dimethylcyclohexylamine and alcohols at different temperatures
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-12-31
    Dan Zhao; Yun Zhuang; Chunshan Fan; Fang Yang; Yuhuan Chen; Xihui Zhang

    Surface tension (γ) for five binary mixtures containing N, N-dimethylcyclohexylamine (DMCA) and alcohol, ethanol, n-propanol, iso-propanol, n-butanol or iso-butanol were measured over the whole range of composition at 0.1 MPa and different temperatures ranging from (288.15 to 308.15) K. From the experimental data, the surface tension deviations (δγ) for the binary mixtures were calculated. The δγ values are positive for all the studied systems and increase with the decreasing of alky chain length of alcohol. For the mixture containing the branched alkyl alcohol, the increase is significant compared with the equivalent molecules with straight chains. According to temperature dependence of surface tension, the thermodynamic parameters, surface enthalpy (Hγ) and surface entropy (Sγ) were also estimated and further discussed.

    更新日期:2019-12-31
  • Thermophysical and volumetric properties of mixtures {carvacrol + ethanol} at several temperatures and atmospheric pressure
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-12-31
    José F. Martínez-López; Juan I. Pardo; José S. Urieta; Ana M. Mainar
    更新日期:2019-12-31
  • Experimental Thermochemical Data of CWA Simulants: Triethyl Phosphate, Diethyl Methylphosphonate, Malathion and Methyl Salicylate
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-12-31
    Greta Bikelytė; Martin A.C. Härtel; Thomas M. Klapötke; Burkhard Krumm; Audrius Sadaunykas

    This work focuses on the determination of important thermochemical properties of several chemical warfare agent (CWA) simulants: diethyl methylphosphonate (DEMP, CAS 683-08-9, 1), triethyl phosphate (TEP, CAS 78-40-0, 2), malathion (CAS 121-75-5, 3) and methyl salicylate (MS, 119-36-8, 4). Enthalpies of vaporization ΔlgHmo. (298.15 K) (1: 56.8±0.8 kJ mol-1; 2: 63.9±0.9 kJ mol-1; 3: 101.4±1.8 kJ mol-1; 4: 59.3±0.8 kJ mol-1) and vapor pressures psat (298.15 K) (1: 43.9 Pa; 2: 12.5 Pa; 3: 1.4 mPa; 4: 14.5 Pa) were determined by the transpiration method in the ambient temperature range. The results were compared with existing literature values and critically evaluated. Data of DEMP 1, TEP 2 and MS 4 show agreement with most literature vaes, while results of malathion 3 show a significant disagreement with the scarce available literature p-T data.

    更新日期:2019-12-31
  • 更新日期:2019-12-23
  • 更新日期:2019-12-20
  • A comparative study of liquid–liquid equilibria for aqueous mixtures of straight chain and branched chain carboxylic acids with methyl isobutyl carbinol
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-12-10
    A. Ghanadzadeh Gilani, F. Amouzadeh, B. Ghalami-Choobar

    Liquid-liquid equilibrium (LLE) data of the (water + butyric or 3-methylbutyric acids + methyl isobutyl carbinol) ternary systems were experimentally obtained at T = (298.2, 303.2, and 308.2) K and P = 0.1 MPa for the first time. Using solubility and tie-line measurements, the triangle phase diagrams were obtained and influence of the chemical structure of the acids on the LLE behaviour was studied. The first ternary aqueous system containing butyric acid and the alcohol displays type-1 LLE behaviour, while the second one including 3-methylbutyric acid exhibits type-2 phase diagram. The reliability of the experimental data was checked using the Othmer-Tobias and Hand correlation equations. The UNIQUAC and NRTL thermodynamic models were used to fit the experimental tie line data and values of the corresponding binary interaction parameters were determined. The binary model parameters were optimized by the MATLAB fminsearch function. According to the experimental tie-line data, distribution coefficients and separation factors were determined for the studied systems.

    更新日期:2019-12-11
  • Phase equilibria of tetra-iso-amyl ammonium bromide (TiAAB) semiclathrates with CO2, N2, or CO2 + N2
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-12-07
    Soyoung Kim, Gyeol Ko, Ki-Sub Kim, Yongwon Seo

    This study examined the thermodynamic stability and guest gas inclusion of tetra-iso-amyl ammonium bromide (TiAAB) semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%), with a primary focus on semiclathrate phase equilibria and Raman spectra. The three-phase (H-LW-V) equilibria of TiAAB semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%) were measured at a stoichiometric concentration (TiAAB 3.7 mol%) using both a conventional isochoric method and a stepwise differential scanning calorimeter (DSC) method. The phase equilibria demonstrated that TiAAB (3.7 mol%) semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%) were significantly stabilized compared with the corresponding CO2, N2, or CO2 (20%) + N2 (80%) gas hydrates. The enclathration of CO2 and N2 molecules in the cages of TiAAB semiclathrates was clearly confirmed via Raman spectroscopy. The experimental results indicate that TiAAB semiclathrates can incorporate CO2 and N2 into the cage lattices at elevated temperatures and lowered pressures and are potential materials for CO2 capture.

    更新日期:2019-12-07
  • 更新日期:2019-12-07
  • 更新日期:2019-12-06
  • A physicochemical and conformational study of co-solvent effect on the molecular interactions between similarly charged protein surfactant (BSA-SDBS) system
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-12-05
    Vivek Sharma, Osvaldo Yañez, Melissa Alegría-Arcos, Ashish Kumar, Ramesh C. Thakur, Plinio Cantero-López
    更新日期:2019-12-05
  • Experimental and simulation study of CO2 and H2S solubility in propylene carbonate, imidazolium-based ionic liquids and their mixtures
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-12-04
    Zhijun Zhao, Ying Huang, Zhaohuan Zhang, Weiyang Fei, Mingsheng Luo, Yongsheng Zhao

    Currently, solvent-based absorption is known as an effective technology to capture acid gases, e.g., CO2 or H2S. In this work, the constant-volume method is used to determine CO2 and H2S solubility in propylene carbonate (PC), imidazolium-based ionic liquids (ILs): 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4], 1-hexyl-3-methylimidazolium tetrafluoroborate [Hmim][BF4], and 1-octyl-3-methylimidazolium tetrafluoroborate [Omim][BF4], and their mixtures at temperature from 303.15 to 333.15 K under pressures up to about 1 MPa. Besides, the quantum chemistry-based COSMO-RS models are used to predict the vapor pressure and the solubility in these solvents. The experimental results illustrate that adding [Omim][BF4] into PC can improve the CO2 and H2S solubility and the H2S/CO2 selectivity compared with the pure PC, which increases with the increasing [Omim][BF4] mass fraction in the mixtures. The simulation with COSMO-RS shows the vapor pressures of PC in the mixtures decreases with the increasing [Omim][BF4] mass fraction. Moreover, the prediction results show that COSMO-RS-Lei model is in much better agreement than COSMO-RS (ADF 2005) for predicting both CO2 and H2S solubility and the prediction accuracy of CO2 is better than that of H2S. Finally, the mixtures of PC and [Omim][BF4] may be used as promising physical solvents to capture CO2 and H2S selectively with high partial pressures because they connect the advantages of organic solvents and ILs.

    更新日期:2019-12-04
  • Thermodynamic study of selected monoterpenes IV
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-12-03
    Vojtěch Štejfa, Michal Fulem, Květoslav Růžička

    An extensive thermodynamic study of three monoterpenes, (−)-menthone, (+)-pulegone, and (−)-isopulegol, is presented in this work. Phase behaviour was investigated by a heat-flux differential scanning calorimetry (DSC) from 183 K resulting in detection of polymorphic behaviour of (−)-isopulegol and a noticeably slow crystallization of (+)-pulegone. Two static apparatus were employed for the vapour pressure measurements over a wide temperature range including environmentally important ambient temperatures. Heat capacities of liquid phase were measured by Tian-Calvet calorimetry at temperatures between 266 K and 353 K. Conformational space of the compounds was examined using the density functional theory (DFT) calculations and the ideal-gas thermodynamic properties were subsequently calculated using statistical thermodynamics. A consistent thermodynamic description was developed using the method of simultaneous correlation, where the experimental data for phase behaviour, vapour pressures, and condensed phase heat capacities and calculated ideal-gas heat capacities are treated together.

    更新日期:2019-12-04
  • Phase behaviour and heat capacities of selected 1-ethyl-3-methylimidazolium-based ionic liquids
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-30
    Vojtěch Štejfa, Jan Rohlíček, Ctirad Červinka

    Ionic liquids start to leave the position of novel and astonishing compounds and become commercially available in a relatively high purity. Consequently, their thermodynamic properties should be described in a more thorough way than in the times of first pioneering studies revealing the importance of the water content. Available thermodynamic data, however, contradict this assumption keeping large discrepancies even among the data published in the most recent papers. Eight common ionic liquids based on the 1-ethyl-3-methylimidazolium cation, [C1C2Im], which are coupled with simple organic or inorganic anions are selected in this work and their phase behaviour, heat capacities, and crystal structures are studied. Special attention is paid to drying of the samples and evaluation of the effect of water content on the melting temperature. Resulting melting temperatures, fusion enthalpies, and heat capacities are compared to the available literature data. For the compounds, which melt above the room temperature, crystal structures were determined using the X-ray powder diffraction experiments to identify the studied crystalline phases. The thermodynamic and crystallographic data were used simultaneously to interpret the polymorphism of the investigated ionic liquids, where it occurred. Moreover, a crystal structure for the dimethyl phosphate salt [C1C2Im][Me2PO4] is reported for the first time.

    更新日期:2019-12-02
  • Volumetric, acoustic and viscometric investigation of some choline amino acid ionic liquids in aqueous solutions of polypropylene glycol 400 and polyethylene glycol 400
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-29
    Mohammed Taghi Zafarani-Moattar, Hemayat Shekaari, Parisa Jafari

    Present study reports density (ρ), ultrasonic velocity (u), and viscosity (η) for some choline amino acid ionic liquids, [Ch][AA]-ILs, including choline glycine, choline L-valine and choline L-proline in aqueous solutions of two water soluble polymers, i.e. polypropylene glycol 400 (PPG400) and polyethylene glycol 400 (PEG400) with different mass fractions of polymer, w/w = (0.025, 0.050 and 0.075), at 298.15 K under atmospheric pressure (≈ 85 kPa). The experimental densities and sound speeds were used for calculation the apparent molar volume (Vφ), limiting apparent molar volume (Vφ0), apparent molar isentropic compressibility (κφ), limiting apparent molar isentropic compressibility (κφ0), and also the transfer molar volume (ΔtranVφ0) and isentropic compressibility (Δtranκφ0) of [Ch][AA] from water to aqueous polymer solutions. Moreover, the viscosity B-coefficient, hydration number (nH), transfer viscosity B-coefficient (ΔtranB), free energies of activation per mole of solvent (Δμ10≠) and solute (Δμ20≠) have been computed by the help of experimental viscosities measured for the studied solutions. These quantities are useful for evaluation the ILs solvation behaviour, their structure-making or breaking abilities in the presence of polymer in water medium and also the solute-solute or solute-solvent interactions exists in aqueous ([Ch][AA] + polymer) solutions. The results indicated that the IL-water interactions are more favourable in the presence of PPG400 and follow the order: [Ch][Gly] > [Ch][L-Pro] > [Ch][L-Val]. Inversely, the IL-water interactions become weaker by ILs transferring from water to aqueous PEG400 solutions.

    更新日期:2019-11-29
  • 更新日期:2019-11-27
  • Solid-Liquid stable phase equilibria of the quaternary system Na+ //Cl−, SO42-, CO32−-H2O and its subsystems Na+ //Cl−, CO32−-H2O and Na+ //SO42-, CO32−-H2O at 353.15 K
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-26
    Shao-Ying Ge, Li Zhu, Yu-Long Ma, Er Liu, Kang-he Zhao

    The solid-liquid phase equilibria of the solution in the quaternary system Na+ //Cl−, SO42−, CO32--H2O and its subsystems Na+ //Cl−, CO32--H2O and Na+ //SO42−, CO32--H2O at 353.15 K were measured by isothermal solution saturation method. The equilibrium solids were determined by the Schreinemaker's method of wet residues and X-ray diffraction (XRD). Based on the experimental data, the phase diagrams were plotted and analysed. There is one monohydrate in the ternary system Na+ //CO32−, Cl−-H2O at T=353.15 K, and the phase diagram contains one invariant point, two univariant curves and four crystallization regions. The ternary system Na+ //SO42−, CO32−−H2O at T=353.15 K is more complex than the previous system since one monohydrate and one anhydrous double salt are found; the phase diagram contains two invariant points, three univariant curves and six crystallization regions. The phase diagram of the quaternary system Na+ //Cl−, SO42−, CO32--H2O at 353.15 K includes two invariant points, five univariant curves, and four crystallization fields of single salts corresponding to NaCl, Na2SO4, Na2CO2·H2O and 2Na2SO4·Na2CO2. The results obtained in this study can help identify the solutions from which fractional crystallization of Na2SO4 and NaCl will be more effective.

    更新日期:2019-11-27
  • Separation of azeotrope 2,2,3,3-tetrafluoro-1-propanol and water: Liquid-liquid equilibrium measurements and interaction exploration
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-25
    Liwen Zhao, Zhaojie Wang, Hui Yang, Dongmei Xu, Lianzheng Zhang, Jun Gao, Yinglong Wang

    Due to the existence of azeotropic point for the mixture 2,2,3,3-tetrafluoro-1-propanol (TFP) and water, liquid-liquid extraction was adopted to separate TFP from its aqueous mixture with cyclohexanone as extractant in this work. The liquid-liquid phase behaviour for the mixture (TFP + water + cyclohexanone) was investigated at T = (293.15, 303.15 and 313.15) K and p = 101.3 kPa. Both selectivity and partition ratio were used for evaluating the extraction performance of cyclohexanone. Also, the NRTL activity coefficient model was applied to fit the measured LLE data with the regressed the parameters. Meanwhile, the binary interaction parameters were validated to be coherent with the measured LLE data based on the mixing surface analysis of Gibbs energy topology. The calculated values of root-mean-square deviation are 0.024, 0.017 and 0.018 at three temperatures, respectively, which indicates the correlated results agree well with the experimental values. Furthermore, the interaction energies between the components were investigated using DMol3 module to explore the molecular interactions between the components in the mixture.

    更新日期:2019-11-26
  • 更新日期:2019-11-22
  • Extended temperature regions of multiferroicity in nanoscale CuO
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-19
    Jacob M. Schliesser, Rebecca E. Olsen, Brian F. Woodfield

    We have measured the magnetic susceptibility and heat capacity of CuO nanoparticles (16 nm) from 2 K to 400 K using a Quantum Design Physical Properties Measurement System (PPMS). The magnetization curves, acquired at various field strengths from 0 Oe to 50 kOe, are similar to literature data of bulk and nanoscale CuO showing a minimum at about 150 K, an upturn as temperature approaches 0 K, and a broad maximum at high temperatures extending beyond 400 K. The heat capacity data between 200 K and 400 K show several broad peaks. The number of these peaks and the temperatures at which they occur differ significantly from the magnetic transitions known to exist in bulk CuO. To further investigate these transitions in nanoscale CuO, we performed temperature dependent x-ray diffraction (XRD) at temperatures from 90 K to 700 K from which lattice parameters as a function of temperature were derived using a Rietveld refinement. Although no phase transitions were observed in these data, changes in the slopes of the lattice parameters are apparent at the transition temperatures observed in the heat capacity and susceptibility measurements. The various transitions in the heat capacity data are attributed to competing ferromagnetic and antiferromagnetic interactions caused by structural properties that are unique to nanophase CuO, and the temperature range of multiferroicity in nanoscale CuO is shown to extend to temperatures higher than those observed for bulk CuO. The heat capacity and temperature dependent XRD measurements are the first of their kind to be reported for CuO nanoparticles.

    更新日期:2019-11-19
  • 更新日期:2019-11-18
  • Speed of sound measurements in liquid methane (CH4) at cryogenic temperatures between (130 and 162) K and at pressures up to 10 MPa
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-14
    G. Cavuoto, S. Lago, P.A. Giuliano Albo, D. Serazio

    This paper reports speed of sound experimental measurements in liquid methane (CH4) along five isotherms, in the temperature range of (130 and 162) K, and for pressures up to 10 MPa. A dedicated experimental apparatus, custom-designed for accurate speed of sound measurement at cryogenic temperatures and high pressures, has been developed and the double pulse-echo technique has been adopted. In order to characterize this new apparatus and its performance, experimental results have been compared with speed of sound values of liquid methane available in literature. A further comparison has been made between the experimental measurements and the speed of sound values obtained using the reference equation of state of methane of Setzmann and Wagner, as well as the GERG-2008 model. The ultrasonic path-length has been calibrated using pure water as a reference fluid, with a relative uncertainty of 0.026 %. The temperature was measured with two platinum resistance thermometers with an absolute uncertainty of 0.02 K. Thermometers have been calibrated using the ITS-90 temperature scale between the triple point of argon and the triple point of water. Finally, the relative expanded uncertainty (k=2) associated to the obtained results is of 0.4 %, mainly influenced by the repeatability of the measurements.

    更新日期:2019-11-14
  • Temperature of maximum density of proteins in water: α-chymotrypsin and bovine serum albumin
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-13
    Jacobo Troncoso, Diego González-Salgado, Luis Romaní

    Density as a function of temperature is determined for a set of α-chymotrypsin and bovine serum albumin solutions in pure water both in the native and the degraded state, the latter achieved by heating them above the denaturation temperature. This allows the temperature of maximum density (TMD) to be obtained against composition. Partial molar volume at infinite dilution of the protein is also calculated. Thermodynamic consistency between composition dependence of TMD and temperature dependence of partial volume is checked, obtaining satisfactory results. TMD behaviour against mass fraction for both native proteins is very similar, but important differences between native and degraded states, and also between the degraded forms of both proteins are found. These results show, for the first time, the strong effects that protein degradation have over the TMD of aqueous solutions, and therefore, over the microscopic structure of water.

    更新日期:2019-11-13
  • Measurements of the thermal conductivity of three pure alcohols and their binary mixtures with methyl myristate component of biodiesel
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-13
    Jing Fan, Shuangshuo Liu, Fenhong Song, Xiaopo Wang

    New experimental thermal conductivity values of 1-propanol, 1-butanol and 1-pentanol in the liquid phase have been reported, and the thermal conductivity of three binary mixtures (1-propanol + methyl myristate, 1-butanol + methyl myristate and 1-pentanol + methyl myristate) have been measured at atmospheric pressure and with the temperature range 292-362 K for the first time. The total standard uncertainty of the experimental results was estimated to be less than 2 % (in the 0.68 confidence level) and the repeatability was better than ± 0.5 %. The liquid thermal conductivity results of three alcohols, 1-butanol/methyl myristate blends and 1-pentanol/methyl myristate blends were fitted as a polynomial function of temperature. In addition, three useful correlations have been optimized by the results of 1-propanol/methyl myristate blends.

    更新日期:2019-11-13
  • Dissolution of sulfur dioxide and nitrogen monoxide in water
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-12
    Fernando Hevia, Barbara Liborio, Karine Ballerat-Busserolles, Yohann Coulier, Jean-Yves Coxam

    Sulfur dioxide (SO2) and nitrogen monoxide (NO) are some of the gas impurities present in the carbon dioxide (CO2) separated from fume using post combustion capture process. Even in a small amount, these impurities may have an impact on storage process development. The dissolution of such gases in aqueous phase is part of the studies carried out to develop processes and analyse the risks in case of geological storage. The enthalpies of solution of SO2 and NO in water were here investigated by calorimetry, using a flow calorimetric technique. The enthalpies of solution were determined at 323.15 K and 373.15 K for sulfur dioxide, and at 323.15 K for nitrogen monoxide. The experimental enthalpy data were used together with available solubility data to test thermodynamic models representative of vapour-liquid equilibrium.

    更新日期:2019-11-13
  • Thermal conductivity measurements for organic liquids at high pressure
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-11
    Francisco Yebra, Jacobo Troncoso, Luis Romaní

    A new instrument for determining the thermal conductivity as a function of temperature and pressure for liquids is described. The system is based on the transient hot wire technique. It is totally automatized: pressure and temperature are controlled and voltage drop through the wire is acquired using a digital system, which automatically performs all required actions. The instrument calibration can be made using only one reference liquid over the whole temperature and pressure ranges. Using rigorous metrological methodologies, it was found uncertainty in thermal conductivity to be around 4%. The thermal conductivity for methanol, ethanol, 1-propanol, heptane, octane, toluene, 1,3-dichloropropane, 1,2-dichloropropane, 1-nitropropane, propionitrile, propionic acid and 1-propylamine, was determined in the temperature and pressure ranges (283.15-313.15) K and (0.1-65) MPa. These data are compared with available literature values; good agreement was obtained for all liquids, which reveals the validity of the experimental procedure. Thermal conductivity data as well as their dependency against temperature and pressure are discussed in terms of the chemical nature of the studied compounds.

    更新日期:2019-11-11
  • Thermodynamic and crystallographic properties Depending on hydration numbers in tetra-n-butylammonium chloride semiclathrate hydrates
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-08
    Motoi Oshima, Yusuke Jin, Masato Kida, Jiro Nagao

    Tetra-n-butylammonium chloride (TBAC) semiclathrate hydrate crystals with hydration numbers n = (26.4 to 33.2) were prepared from TBAC aqueous solutions over the range of TBAC mole fractions (0.0060 to 0.0500). The thermodynamic and crystallographic properties of the TBAC hydrates were then investigated via ion chromatography, powder X-ray diffraction (PXRD), and differential scanning calorimetry. The crystal system of the TBAC hydrates with n = (26.4 to 33.2) was tetragonal, while the crystal structures (PXRD patterns) slightly varied with the hydration numbers. The dissociation enthalpies per guest mole (TBAC) gradually varied with the hydration numbers, from ∼149 kJ mol−1 at n = 26.4 to ∼187 kJ mol−1 at n = (33.1 to 33.2). These results suggest that the enthalpies per TBAC increased with greater hydrogen-bond formation in the TBAC hydrate crystals. The dissociation temperatures and dissociation enthalpies per H2O of the TBAC hydrates suggest that the hydrate crystals were most thermally stable at around n = 30 and slightly unstable with higher/lower hydration numbers.

    更新日期:2019-11-08
  • Adsorption of metformin from an aqueous solution by Fe-ZSM-5 nano-adsorbent: Isotherm, kinetic and thermodynamic studies
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-07
    Hadi Adel Niaei, Mohammad Rostamizadeh

    Metformin (MET) is one of the anti-diabetic drugs which is widely used in the world and found abundantly in pharmaceutical wastewater. The purpose of this study, the adsorption of MET from aqueous solution by Fe-ZSM-5 (Fe-Z) zeolite as an adsorbent. The zeolite characterization was analyzed using FTIR, FE-SEM, TEM, XRD, and N2 adsorption-desorption Techniques. The adsorption was performed in a batch system, and the effect of parameters such as solution pH, initial concentration of MET, adsorbent dose, temperature, and contact time was investigated to optimize the adsorption process. Adsorption isotherms were studied by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models. The Langmuir model with a high correlation coefficient (R2 = 0.999) and the maximum monolayer adsorption capacity (qmax = 14.992 mg g-1) at T = 25 °C showed the highest consistent with MET adsorption on the Fe-Z zeolite. The kinetic data were best represented by the pseudo-second-order model. Also, thermodynamic parameters such as enthalpy changes (ΔḢ), Gibbs energy changes (ΔĠ), and entropy changes (ΔṠ) were investigated. The highest adsorption efficiency was 95.7% at the optimum operating conditions: pH = 8.33, t= 25 °C, 1.1 g L-1 Fe-Z and C0 = 10 mg L-1. The developed nano-adsorbent had high reusability including only 4.4% drop in the removal efficiency. The results showed that the Fe-Z zeolite could be a promising adsorbent for the MET removal.

    更新日期:2019-11-07
  • Enthalpy of formation of aqueous hydrofluoric acid: revision needed?
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-11-07
    Eugene Paulechka, Andrei Kazakov

    Accurate enthalpies of formation of hydrofluoric acid in the gas and liquid states as well as in aqueous solutions are critical for reduction and interpretation of combustion calorimetry data for fluorinated compounds. Analysis of current recommendations reveals inconsistencies with the existing literature that can significantly affect experimental values derived using these recommendations. Through thorough and comprehensive analysis of available experimental data, including the sources not considered before, we provide recommendations that substantially improve consistency with these results. However, the scatter in the existing data also prevents further improvements and uncertainty reduction. New experimental data, particularly for aqueous HF solutions, are needed to advance.

    更新日期:2019-11-07
  • Evaluation of solute-solvent interaction and phase separation for aqueous polymers solutions containing choline chloride/D-sucrose natural deep eutectic solvent through vapor-liquid equilibria, volumetric and acoustic studies
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-09-19
    Mohammed Taghi Zafarani-Moattar, Hemayat Shekaari, Fariba Ghaffari

    In polymer-based aqueous biphasic systems (ABSs), the understanding the role of different types of polymers in phase separation is important in the selection of a suitable ABS used for separation of biomaterials. For this purpose, in this work, a systematic investigation of ternary aqueous solutions containing one deep eutectic solvent (NADES) obtained from mixtures of choline chloride as HBA and D-sucrose as HBD, and different water soluble polymers polyethylene glycol 400 (PEG400), polypropylene glycol 400 (PPG400), and polyethylene glycol dimethyl ether 250 (PEGDME250) at a molar ratio of 1:1 was made by the volumetric, ultrasonic, and vapor-liquid equilibria (VLE) studies at T = 298.15 K. The obtained water iso-activity lines showed that the system containing PPG400 and NADES has negative deviation from the semi-ideal solution and therefore solute-solvent interactions are unfavorable suggesting the occurrence of phase separation in this system. But in the case of PEG400 and PEGDME250 these deviations are positive and there are favorable interactions between the polymers and NADES which means that phase separation in these systems is unlikely. The obtained values from the density and acoustic studies were used for calculating the limiting values for apparent molar volume Vφ0, apparent molar isentropic compressibility kφ0, the transfer molar volume ΔtrVφ0, and also isentropic compressibility Δtrkφ0 of polymers from water to aqueous NADES solutions. These results are consistent with the results of water activity measurements in regard to the solute-solvent interactions and phase separation in the studied ternary systems.

    更新日期:2019-11-04
  • Solid-liquid equilibrium and thermodynamic properties of dipyridamole form II in pure solvents and mixture of (N-methyl pyrrolidone + isopropanol)
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-10-25
    Rongrong Li, Liting Fu, Jieyu Zhang, Wei Wang, Xianlang Chen, Jia Zhao, Deman Han
    更新日期:2019-11-04
  • 更新日期:2019-11-04
  • Measurement of low-temperature heat capacity by relaxation technique: Calorimeter performance testing and heat capacity of benzo[b]fluoranthene, benzo[k]fluoranthene, and indeno[1,2,3-cd]pyrene
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-09-28
    Tomáš Mahnel, Václav Pokorný, Michal Fulem, David Sedmidubský, Květoslav Růžička

    Experimental heat capacities of three polycyclic aromatic hydrocarbons (PAHs), benzo[b]fluoranthene (CAS RN: 205-99-2), benzo[k]fluoranthene (CAS RN: 207-08-9), and indeno[1,2,3-cd]pyrene (CAS RN: 193-39-5) in the temperature range (2–300) K are reported (to our knowledge for the first time). Commercially available relaxation calorimeter was used for measurement. Performance of the apparatus was tested by measuring the heat capacity of copper and sapphire. However, PAHs are available in a form of powder and therefore cannot be directly placed on measuring platform as e.g. copper specimen; moreover, sample sublimation cannot be ruled out. Modified three-step method using powder sample or powder sample pressed into a pellet and inserted into aluminium DSC pans of different weights was tested by measurement of anthracene heat capacity, for which high quality data are available in the literature. Pellets of higher weight in a pan of higher mass yielded results in the best accordance with the literature data; this method was applied also for measurement of benzoic acid heat capacity. Finally, datasets on heat capacity of benzo[b]fluoranthene, benzo[k]fluoranthene, and indeno[1,2,3-cd]pyrene were recorded, smoothed and standard thermodynamic functions in the temperature range (0–300) K were calculated; standard entropy in crystalline state at 298.15 K is 270.1 ± 5.4 J·K−1·mol−1 for benzo[b]fluoranthene, 263.5 ± 5.3 J·K−1·mol−1 for benzo[k]fluoranthene, and 272.8 ± 5.4 J·K−1·mol−1 for indeno[1,2,3-cd]pyrene.

    更新日期:2019-11-04
  • Isopiestic determination of the osmotic and activity coefficients of {yK2HPO4 + (1 − y)KH2PO4}(aq) at T = 298.15 K
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-09-27
    Tijana Ivanović, Daniela Ž. Popović, Jelena Miladinović, Joseph A. Rard, Zoran P. Miladinović, Ferenc T. Pastor

    Isopiestic measurements have been made at 55 compositions of the {yK2HPO4 + (1 − y)KH2PO4}(aq) system at T = (298.15 ± 0.01) K, 11 for each of the limiting binary solutions and 33 for mixture compositions at K2HPO4 stoichiometric ionic strength fractions y = (0.23330, 0.47671, and 0.73177), using KCl(aq) as the reference standard. Model parameters for the binary subsystems were evaluated at this temperature for an extended form of Pitzer’s ion-interaction model and also for the Clegg, Pitzer and Brimblecombe model based on the mole-fraction-composition scale, using the present isopiestic results along with critically-assessed osmotic coefficients for both of these aqueous electrolytes as extracted from the published literature. The thermodynamic models for KH2PO4(aq) extend to slightly above the saturated solution molality at T = (298.15 ± 0.01) K, whereas those for K2HPO4(aq) extend to m = 9.7429 mol·kg−1, which is the molality of the saturated solution, also at T = (298.15 ± 0.01) K. These results yield the CODATA-compatible standard Gibbs energy of formation ΔfGmo(K2HPO4·3H2O,cr,298.15K)=-2367.70±1.60kJ·mol-1. The 33 osmotic coefficients for the ternary mixtures were likewise represented with these models, using both the usual Pitzer mixing terms and also Scatchard’s neutral-electrolyte model mixing terms for the extended ion-interaction model. Two mixing parameters are needed for each of the three models for {yK2HPO4 + (1 − y)KH2PO4}(aq), and both of these ion-interaction models give similar high-quality representations of the experimental results. However, the Clegg, Pitzer and Brimblecombe model had more difficulty in representing the osmotic coefficients of K2HPO4(aq), especially below 3 mol·kg−1, and consequently the corresponding mixture model with two mixing parameters is slightly less accurate for representing the osmotic coefficients. The maximum difference in calculated values of the mean molality-based activity coefficients for the two recommended extended Pitzer models with the different types of mixing terms are 0.0061 for the trace activity coefficient of K2HPO4(aq) in KH2PO4(aq) but with much better agreement at most mixture compositions.

    更新日期:2019-11-04
  • Thermodynamics of bis-dioxolene cobalt complex with imino-pyridine functionalized by TEMPO moiety
    J. Chem. Thermodyn. (IF 2.29) Pub Date : 2019-10-10
    A.V. Markin, N.N. Smirnova, V.M. Fomin, A.A. Zolotukhin, A.V. Arapova, M.P. Bubnov, V.K. Cherkasov

    Firstly in the present research, the heat capacity of bis-dioxolene cobalt complex with imino-pyridine functionalized by TEMPO moiety (TEMPO-Im-Py)Co(3,6-DBSQ)2 was measured over the range T = (6 and 347) K by the precise adiabatic vacuum calorimeter. In the temperature interval of T = (220 to 285) K, the phase transition in the crystalline state was observed, and its standard thermodynamic characteristics were determined. The standard thermodynamic functions (p° = 0.1 MPa) of (TEMPO-Im-Py)Co(3,6-DBSQ)2(cr), namely Cp,mo, Δ0THmo, Δ0TSmo and Δ0TGmo, were calculated using the obtained experimental data from T → 0 to 350 K. The low-temperature (T < 50 K) heat capacity dependence was analysed on the basis of the Debye heat capacity theory of solids and its multifractal model, so the characteristic temperature and the fractal dimension were determined, and chain-layered structure topology of the studied complex was established.

    更新日期:2019-11-04
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