A simple approach for THE DETERMINATION AND CHARACTERIZATION OF TERNARY PHASE DIAGRAMS of aqueous two-phase systems composed of water, poly(ethylene) glycol and sodium carbonate

  • Emanuel V. Capela
  • João H.P.M. Santos
  • Isabel Boal-Palheiros
  • Pedro J. Carvalho
  • João A.P. Coutinho
  • Sónia P.M. Ventura
  • Mara G. Freire


In this work, an experimental protocol to determine liquid-liquid phase diagrams of aqueous two-phase systems (ATPS) in a chemical engineering course is described. Throughout this laboratory set of experiments, students will determine liquid-liquid ternary phase diagrams, comprising the solubility curves, tie-lines, tie-line lengths and critical points, for systems composed of poly(ethylene) glycol, sodium carbonate and water. Furthermore, students will apply the NRTL (Non-Random Two Liquid) model to fit the experimental tie-lines.