The paper reports the three-phase (gas + aqueous liquid + hydrate) equilibrium pressure (p) versus temperature (T) data for a (O 3 + O 2 + CO 2 + H 2O) system and, for comparison, corresponding data for a (O 2 + CO 2 + H 2O) system for the first time. These data cover the temperature range from (272 to 279) K, corresponding to pressures up to 4 MPa, for each of the three different (O 3 + O 2)-to-CO 2 or O 2-to-CO 2 mole ratios in the gas phase, which are approximately 1:9, 2:8, and 3:7, respectively. The mole fraction of ozone in the gas phase of the (O 3 + O 2 + CO 2 + H 2O) system was from ∼0.004 to ∼0.02. The modified pressure-search method, developed in our previous study [S. Muromachi, T. Nakajima, R. Ohmura, Y.H. Mori, Fluid Phase Equilib. 305 (2011) 145-151] for p-T measurements in the presence of chemically unstable ozone, was applied, having been further modified for dealing with highly water-soluble CO 2, for the (O 3 + O 2 + CO 2 + H 2O) system, while the conventional temperature-search method was used for the (O 2 + CO 2 + H 2O) system. The measurement uncertainties (with 95% coverage) were ±0.11 K for T, ±6.0 kPa for p, and ±0.0015 for the mole fraction of each species in the gas phase. It was confirmed that, at a given CO 2 fraction in the gas phase, p for the (O 3 + O 2 + CO 2 + H 2O) system was consistently lower than that for the (O 2 + CO 2 + H 2O) system over the entire T range of the present measurements, indicating a preference of O 3 to O 2 in the uptake of guest-gas molecules into the cages of a structure I hydrate.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Materials Science(all)
- Physical and Theoretical Chemistry