Separations analysis fundamentals - Principles of Chemical Separations with Environmental Applications - page 61

Table 3.3 Equilibrium data (wt%).

Furfural Glycol Water

94.8 0.0 5.2

84.4 11.4 4.1

63.1 29.7 7.2

49.4 41.6 9.0

40.6 47.5 11.9

33.8 50.1 16.1

23.2 52.9 23.9

20.1 50.6 29.4

10.2 32.2 57.6

9.2 28.1 62.2

7.9 0.0 92.1

Table 3.4 Mutual equilibrium (tie-line) data
(wt%) for furfural-ethylene glycol-water.

Glycol in water layer Glycol in solvent layer

7.7 28.9

6.1 21.9

4.8 14.3

2.3 7.3

11.5 41.8

32.1 48.8

Example 3. : single equilibrium-limited stage (reproduced with permission of
publisher, copyright c 1998, J. Wiley and Sons, Inc.)

Problem:
Ethylene glycol is mixed with water as anti-freeze in car engines. Rather than dispose
of this mixture, removal of the ethylene glycol and recycle are preferred. Furfural
(F) is suggested as a solvent for removing ethylene glycol (G) from water (W) in
an extraction process. The equilibrium solubility and tie-line data for 25 ◦ C are
given in Tables 3.3 and 3.4 [10]. Using these data, construct an equilibrium phase
diagram and:
(a) calculate the composition of the equilibrium phases produced when a 45 wt%
glycol-in-water solution is contacted with its own weight in furfural. Show the
process on the diagram.
(b) show the composition of the water-glycol mixture obtained if all the furfural is
removed from the extract obtained in (a).