Basic Approaches to Separation. Analysis and Classification of Methods According to Underlying Transport Characteristics

Abstract

We note the loss of opportunities in the historical fragmentation of separation science, and give arguments for an increased unification of approaches in the future. The complexities of classifying separation methods are discussed, and it is suggested that the science of taxonomy must be invoked to make comprehensive advances toward realistic polythetic classifications. Some basic elements of a classificatory system are described in terms of the type of displacement leading to separation and the profile of the driving force leading to relative displacement. The driving forces may be continuous (c) or discontinuous (d), arising in external fields and interfacial interactions, respectively. Flow may be integral to the separation (F) by its occurrence parallel (F(=)) or perpendicular (F(+)) to the force, or the system may be effectively static (S). These considerations lead to six fundamental categories for most separations: Sc, Sd, F(=)c, (F(=)d, F(+)c, and F(+)d. Examples are given for each category. Finally, the above classificatory system is justified by fundamental considerations of transport in separation systems.