We showed the stability (dissociation potential) of CO2 hydrate by measuring its phase equilibrium under different marine geochemical conditions (temperature: 275 � 280 K and pressure: 2.0 � 3.0 MPa). The phase equilibrium of CO2 hydrate in aqueous solution with 3.5% NaCl and 0.1M NaHCO3 was observed in high pressure region, compared to that in pure aqueous solution (control). Glycine, highly soluble protein-like compound, added to aqueous solution also increased equilibrium pressure, while humic substance mixture barely changed equilibrium conditions (temperature and pressure) compared to the control. In soil mineral (illite and pyrite) suspensions, the equilibrium conditions were hardly changed even at different suspensions pHs. The phase equilibrium of Ulleung basin (UB; East Sea of Korea) sediment suspension was very similar to that of the control. However, in the absence of organic fractions in UB sediment by baking the sediment, the equilibrium pressure in the sediment suspension was observed to increase. The results suggest that different interactions among water and CO2 molecules, soil minerals, and organic compounds can significantly affect the stability of CO2 hydrate phase equilibrium.

Effect of marine geochemical conditions on the phase equilibrium of carbon dioxide hydrate

242nd National Meeting (2011)

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