From unit operations to separation processes

The Arthur D. Little concept of unit operations embodied a number of differ ent methods of separating mixtures and represented a major advance in chemi cal engineering. Over time, those and subsequent concepts have evolved into a unified field of separation processes. The ways in which this happened a re traced. The more unified view of separations enables more coherent and p owerful approaches for process selection and design, reducing energy requir ements, for selecting separating agents, understanding the complex interact ions of mass transfer and phase equilibria, and identifying new methods for separating complex mixtures. As such, separation processes provide one of the most effective vehicles for teaching and understanding the engineering of chemical processes.