a. A separation is to be carried out in an N-stage cross-flow configuration using the same feed/solvent ratio in each stage. The total feed/solvent ratio is therefore ∧/N. Compute the minimum solvent required for a given separation factor s_N. (That is, find the limit as N→∞.)
b. Repeat the calculations in Problem 11.3a for this case and compare the minimum solvent requirements.

Problem 11.3a

a. What is the minimum solvent flow rate that can be used in countercurrent operation to remove 75 percent of the acetic acid in the process stream described in Problem 11.1?

Problem 11.1

It is necessary to process 100 kg/min of a water stream containing 15 percent acetic acid by weight. How much acid can be extracted in a single equilibrium stage with pure isopropyl ether using

(a) 100 kg/min of solvent?

(b) 50 kg/min? Assume negligible solute transfer between phases.