Liquid−Liquid Equilibria of Aqueous Two-Phase Systems Containing Poly(ethylene glycols) of Different Molecular Weight and Sodium Citrate

• Published in: Journal of chemical and engineering data Vol. 51; no. 1; pp. 209 - 212
• Main Authors: Tubío, Gisela, Pellegrini, Luciana, Nerli, Bibiana B, Picó, Guillermo A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.01.2006
• Subjects: Applied sciences; Chemistry; Exact sciences and technology; General and physical chemistry; Liquid-liquid equilibria; Organic polymers; Phase equilibria; Physicochemistry of polymers; Properties and characterization; Thermal and thermodynamic properties; Ethylene oxide polymer; Biphasic system; Phase diagram; Aqueous medium; Phase equilibrium; Molecular mass; Liquid liquid equilibrium
• ISSN: 0021-9568; 1520-5134
• DOI: 10.1021/je050332p

The phase diagrams corresponding to systems of sodium citrate and poly(ethylene glycol) of different molecular weights (600, 1000, 1450, 3350, and 8000) were determined at (22, 37 and 50) °C. Moreover, the medium pH (5.2, 8.2, and 9.2) effect was also studied. The binodal curves were described using a four-parameter sigmoidal equation, and the tie-lines were satisfactorily described using the Othmer−Tobias and Bancroft equations. An increase in temperature and pH caused the expansion of the two-phase area. The binodal curves became more asymmetric and close to the origin with an increase in poly(ethylene glycol) molecular weight.