Acetic acid is to be extracted from a dilute aqueous solution with isopropyl ether at 25oC in a countercurrent cascade of mixer-settler units. In one of the units, the following conditions apply:

Interfacial tension =13.5 dyne/cm. If the raffinate is the dispersed phase and the mixer residence time is 2.5 minutes, estimate for the mixer:

(a) The dimensions of a closed, baffled vessel,

(b) The diameter of a flat-bladed impeller,

(c) The minimum rate of rotation in revolutions per minute of the impeller for complete and uniform dispersion, and

(d) The power requirement of the agitator at the minimum rate of rotation.

Extract Raffinate Flow rate, lb/h Density, Ib/ft3 Viscosity, cP 21,000 63.5 52,000 45.3 3.0 1.0