Abstract
Attachment of particles and droplets to bubbles—the latter being of various fine sizes and created by different techniques (as described in detail)—forms the basis of flotation, a process which indeed was originated from mineral processing. Nevertheless, chemistry often plays a significant role in this area, in order for separation to be effective, as stressed. This (brief) review particularly discusses wastewater treatment applications and the effect of bubble size (from nano- to micro-) on the flotation process.