Phase equilibrium condition measurements in carbon dioxide hydrate forming system coexisting with seawater

Three phase equilibrium conditions of synthetic standard (seawater + carbon dioxide hydrate + carbon dioxide gas) were experimentally determined based on the batch, isochoric procedure. The total mass fraction of the electrolytes in the synthetic standard seawater, w_ss, was 0.0351, 0.0700, or 0.1036 that was composed of pure water and seven salts. The equilibrium pressure–temperature conditions were as follows: 271.95 K < T < 279.05 K and 1.298 MPa < p < 3.144 MPa in the system having w_ss = 0.0351, 272.25 K < T < 278.15 K and 1.530 MPa < p < 3.361 MPa in the w_ss = 0.0700 system and 271.15 K < T < 275.65 K and 1.643 MPa < p < 2.909 MPa in the w_ss = 0.1036 system. The quantitative evaluation of the changes in the equilibrium temperature at a fixed pressure was performed by applying the equilibrium conditions to the Clausius–Clapeyron equation. The results are essential to design the thermodynamic conditions for the clathrate hydrate-based seawater desalination technology.