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Title: Multiphase behavior of ternary mixtures consisting of carbon dioxide, water, and a model nonionic surfactant at elevated pressures

Miscellaneous ·
OSTI ID:6130774

The equilibrium multiphase behavior for ternary mixtures consisting of carbon dioxide and water with 2-butoxyethanol (C{sub 4}E{sub 1}) and with n-octyl tri(oxyethylene glycol) monoether (C{sub 8}E{sub 3}) was studied at temperatures and pressures near the critical point of carbon dioxide. Four-phase, liquid-liquid-liquid-gas equilibrium and multiple regions of three-phase, liquid-liquid-gas and liquid-liquid-liquid equilibria were observed for both ternary mixtures. The complex multiphase behavior exhibited by these mixtures is important in industrial processes such as supercritical fluid extractions and the modelling of tertiary oil recovery processes involving miscible gas displacement. Phase compositions, molar volumes, and mass densities were measured for three-phase and four-phase equilibria for ternary carbon dioxide-water-C{sub 4}E{sub 1} and carbon dioxide-water-C{sub 8}E{sub 3} mixtures at temperatures ranging from 30{degree}C to 50{degree}C and pressures ranging from 915 psia to 1,415 psia. Critical endpoint temperatures and pressures which bound the multiphase equilibria were also measured. A new experimental apparatus was developed and used with a stoichiometric technique that allows phase compositions and densities to be determined from phase volume measurements obtained by visual observation. Sampling of the individual phases which can disturb equilibrium is therefore not required. The complex equilibrium multiphase behavior for these ternary mixtures was described using geometrical representations of the experimental measurements along with knowledge of the topological constraints imposed on phase diagrams by the Gibbs phase rule. Dye solubilization and dynamic light scattering experiments were used to indicate the existence of microstructures in the equilibrium phases of the ternary mixtures.

Research Organization:
Delaware Univ., Newark, DE (USA)
OSTI ID:
6130774
Resource Relation:
Other Information: Thesis (Ph.D)
Country of Publication:
United States
Language:
English