12.8. Dilute Multisolute Absorbers and Strippers

Up to this point we have been restricted to cases where there is a single solute to recover. Both the stage-by-stage McCabe-Thiele procedures and the Kremser equation can be used for multisolute absorption and stripping if certain assumptions are valid. The single-solute analysis by both procedures required systems that 1) are isothermal, 2) are isobaric, 3) have a negligible heat of absorption, and 4) have constant flow rates. These assumptions are again required.

To see what other assumptions are required consider the Gibbs phase rule for a system with three solutes plus a solvent and a carrier gas. The phase rule is