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This paper reports the experimental values of the interfacial tension between a gas mixture (CO2 + H2) and water measured with the pendant drop method. The measurements were conducted for temperatures from 271.2 K to 280.2 K and pressures up to 7.0 MPa, at increments of 1 MPa. These temperature-pressure ranges were nearly close to the (CO2 + H2) hydrate-stability-zone but each result is obtained without existence of any hydrate. The temperature dependency of the interfacial tension in this system could not be observed, but the interfacial tension decreased almost linearly with increasing pressure, indicating that the observed decrease was caused by an increase in adsorption of the gas phase onto the liquid water with pressure. The gradient of the interfacial tension, with respect to the pressure, was confirmed to be determined by the gas phase composition. The interaction between gases has a marginal influence on the interfacial tension between the (CO2 + H2) gas mixture and water.

This paper reports experimental values of the surface tension between CO2 gas and tetra-n-butylammonium bromide (TBAB) aqueous solution measured by the pendant drop method. The experimental conditions were pressures from 1.00 MPa to 4.00 MPa, temperatures from 288.15 K to 303.15 K and wTBAB from 0.10 to 0.40, where wTBAB denotes the mass fraction of TBAB in the aqueous solution. These pressure–temperature-composition conditions partially fall into the stability zone of (CO2 + TBAB) semiclathrate hydrate but all data were obtained without any hydrate in the system. Surface tension decreased with increasing wTBAB and pressure but temperature dependency was not observed. Compared to the air–TBAB aqueous solution system and CO2–water system, the values of the surface tension were smaller.

Accepted: 2010-02-07, 資料番号: SA1000813000

Densities (ρ) for binary systems of (1,2,4-trimethylbenzene, or 1,3,5-trimethylbenzene + propyl acetate, or butyl acetate) were determined at four temperatures (298.15, 303.15, 308.15, and 313.15) K over the full mole fraction range. The excess molar volumes (VE) calculated from the density data show that the deviations from ideal behaviour in the systems (all being positive, excepting 1,2,4-trimethylbenzene + butyl acetate system) become more positive with the temperature increasing. Surface tensions (σ) of these binary systems were measured at the same temperatures (298.15, 303.15, 308.15, and 313.15) K by the pendant drop method, the surface tension deviations (δσ) for all system are negative, and decrease with the temperature increasing. The VE and δσ are fitted to the Redlich–Kister polynomial equation. Surface tensions were also used to estimate surface entropy (Sσ) and surface enthalpy (Hσ).

Enthalpy increment Δ298.15 KTHmo measurements were made on Na2MoO4(s) and Na2Mo2O7(s) in the temperature range 335 K to 760 K by the drop method using a high-temperature Calvet calorimeter. The calorimeter was calibrated using an electrical method and synthetic sapphire SRM-720 (Al2O3). An on-line computer was used for acquiring and processing results from the calorimeter. The enthalpy increments for Na2MoO4(s) and Na2Mo2O7(s) were least-squares fitted to a polynomial with temperature and are given by: Na2MoO4(s): Δ T 298.15 K H ∘ /(J·mol −1 )±109=−38795+113.7(T/K)+0.0546(T/K) 2 , (335 to 520 K) Δ T 298.15 K H ∘ /(J·mol −1 )±111=−38598+142.8(T/K)+0.00458(T/K) 2 , (520 to 720 K) Δ T 298.15 K H ∘ /(J·mol −1 )±538=−105740+270.7(T/K) (720 to 760K) Na 2 Mo 2 O 7 (S): Δ T 298.15 K H ∘ /(J·mol −1 )±318=−62413105740+190.6(T/K)+0.0589(T/K) 2 , (335 to 760 K) The thermal properties of Na2MoO4 and Na2Mo2O7 were obtained using the above experimental values. These are the first experimental results on the thermal properties of these compounds.

The excess enthalpies HE and the limiting partial enthalpies of liquid mixtures of the (Na+ + K+ + F− + SO42−) molten-salt reciprocal system were measured with a high-temperature calorimeter by an improved drop method. From HE's measured for the two diagonals: (NaF + K2SO4) and (KF + Na2SO4), we obtained the enthalpy difference ΔHo associated with the characteristic exchange reaction: 1 2 Na 2 SO 4 ( l ) + KF(l) = NaF(l) + 1 2 K 2 SO 4 ( l ) . This value is in good agreement with that calculated from thermodynamic quantities for the four pure salts. We propose a theoretical approach to interpret the mixing mechanism in a (A+ + B+ + X− + Y2−) asymmetrical reciprocal system: it makes possible an estimate of the excess thermodynamic quantities from those for the four common-ion binary mixtures and from ΔHo. This model has been applied to (NaF + K2SO4) and (KF + Na2SO4) and the results obtained were compared with the experimental excess enthalpies.