Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

In situ measurement of liquid-liquid equilibria by medium field nuclear magnetic resonance

Friebel, A.[Anne], Froscher, A.[Agnes], Munnemann, K.[Kerstin], Harbou, E. v.[Erik von], Hasse, H.[Hans]
Fluid Phase Equilib. 2017, 438, 44-52
ABSTRACT
A new method for non-invasive measurement of liquid-liquid equilibria (LLE) using a compact medium field nuclear magnetic resonance (NMR) spectrometer is presented. Mixing of all components, phase separation, and analysis of the composition of the coexisting phases is performed in situ in an NMR glass tube. Thus, the experimental effort is reduced and errors caused by sampling are eliminated. Furthermore, calibration of the analysis method is not necessary as quantitative information is obtained directly from the NMR spectra. The proposed method for studying LLE in situ can be swiftly conducted in standard chemical laboratories as medium field NMR spectrometer do not require dedicated laboratory infrastructure but enable convenient handling and fast analysis of the samples. In the present work, four non-reactive ternary solvent systems with closed miscibility gap (toluene + acetone + water, diethyl ether + acetone + water, diethyl ether + methanol + water, and acetonitrile + ethanol + cyclohexane) and one reactive ternary system (water + acetic acid + acetic anhydride) were investigated at a temperature of 22.0 degC using 1H medium field NMR spectroscopic measurements. For comparison, the composition of the coexisting phases is also examined for one non-reactive system (acetonitrile + ethanol + cyclohexane) using 13C medium field NMR spectroscopy as well as spatially resolved spectroscopy in a conventional high field NMR spectrometer. The comparison of the results of the present work to literature data shows that the new proposed method enables swift and reliable investigations of LLE.
Compounds
# Formula Name
1 C6H12 cyclohexane
2 C4H10O diethyl ether
3 C2H3N acetonitrile
4 CH4O methanol
5 C2H6O ethanol
6 C7H8 toluene
7 C3H6O acetone
8 H2O water
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 2
  • 4
  • 8
  • Mole fraction - 2 ; Liquid mixture 1
  • Mole fraction - 2 ; Liquid mixture 2
  • Mole fraction - 4 ; Liquid mixture 2
  • Mole fraction - 4; Liquid mixture 1
  • Temperature, K; Liquid mixture 2
  • Pressure, kPa; Liquid mixture 2
  • Liquid mixture 1
  • Liquid mixture 2
  • OTHER
  • OTHER
  • OTHER
  • 4
  • POMD
  • 7
  • 6
  • 8
  • Mole fraction - 6 ; Liquid mixture 1
  • Mole fraction - 6 ; Liquid mixture 2
  • Mole fraction - 7 ; Liquid mixture 2
  • Mole fraction - 7; Liquid mixture 1
  • Temperature, K; Liquid mixture 2
  • Pressure, kPa; Liquid mixture 2
  • Liquid mixture 1
  • Liquid mixture 2
  • OTHER
  • OTHER
  • OTHER
  • 10
  • POMD
  • 5
  • 3
  • 1
  • Mole fraction - 5 ; Liquid mixture 2
  • Mole fraction - 3 ; Liquid mixture 1
  • Mole fraction - 5 ; Liquid mixture 1
  • Mole fraction - 3; Liquid mixture 2
  • Temperature, K; Liquid mixture 2
  • Pressure, kPa; Liquid mixture 2
  • Liquid mixture 2
  • Liquid mixture 1
  • OTHER
  • OTHER
  • OTHER
  • 4
  • POMD
  • 5
  • 3
  • 1
  • Mole fraction - 5 ; Liquid mixture 2
  • Mole fraction - 3 ; Liquid mixture 1
  • Mole fraction - 5 ; Liquid mixture 1
  • Mole fraction - 3; Liquid mixture 2
  • Temperature, K; Liquid mixture 2
  • Pressure, kPa; Liquid mixture 2
  • Liquid mixture 2
  • Liquid mixture 1
  • OTHER
  • OTHER
  • OTHER
  • 3
  • POMD
  • 5
  • 3
  • 1
  • Mole fraction - 3 ; Liquid mixture 1
  • Mole fraction - 5 ; Liquid mixture 2
  • Mole fraction - 3 ; Liquid mixture 2
  • Mole fraction - 5; Liquid mixture 1
  • Temperature, K; Liquid mixture 2
  • Pressure, kPa; Liquid mixture 2
  • Liquid mixture 1
  • Liquid mixture 2
  • OTHER
  • OTHER
  • OTHER
  • 7
  • POMD
  • 2
  • 7
  • 8
  • Mole fraction - 7 ; Liquid mixture 1
  • Mole fraction - 2 ; Liquid mixture 2
  • Mole fraction - 7 ; Liquid mixture 2
  • Mole fraction - 2; Liquid mixture 1
  • Temperature, K; Liquid mixture 2
  • Pressure, kPa; Liquid mixture 2
  • Liquid mixture 1
  • Liquid mixture 2
  • OTHER
  • OTHER
  • OTHER
  • 5