Separation Processes

Shortcut multicomponent column design uses three correlations: Fenske gives the minimum stages at total reflux, Underwood gives the minimum reflux, and Gilliland links actual stages to actual reflux between those limits.

Liquid-liquid extraction transfers a solute from feed to an immiscible solvent according to a distribution coefficient; multistage design is done on a ternary equilibrium diagram using tie lines and the lever rule, with counter-current contacting giving the best recovery.

Leaching dissolves a soluble constituent out of a solid using a solvent; design tracks the solute through overflow (clear solution) and underflow (wet solids carrying entrained liquor), typically in a counter-current cascade to maximise recovery.

Membrane processes separate by selective permeation through a barrier; the flux is proportional to a driving force (pressure for RO, minus the osmotic-pressure penalty), and performance is measured by rejection and the stage cut.

Adsorption and ion exchange remove solutes onto a solid whose equilibrium capacity follows a Langmuir or Freundlich isotherm; fixed beds operate by passing feed until a moving mass-transfer zone reaches the outlet, causing breakthrough.