Separation Using Foaming Techniques

Separation of various chemical components from each otheJO is often the most difficult step in analytical procedures. The problems attached to separation become further magnified when the species concentations are extremely low. A group of techniques that has proven useful especially in dilute solutions for separating and concentrating metallic as well as nonmetallic ions and complexes, proteins, microorganisms, particulates, etc. is the adsorptive bubble separation techniques. Minerals have indeed been treated using some of these techniques for decades. The success of these processes is primarily dependent upon differences in the natural surface activity of various species or particulates in the system or in their tendency to associate with surfactants. The efficiency of the process is determined by such variables as solution pH, ionic strength, concentration of various activating and depressing agents, and temperature. A proper control of variables offers an opportunity to separate a variety of metallic and nonmetallic species and particulates. In this paper the principles governing various foam separation techniques. particularly froth ftotation, are presented along with the recent results on the role of variables that can be controlled to achieve complete removal of species and particulates for analytical purposes.