ABSTRACT
Adsorption is the term used to describe the state of a system, composed of two phases in contact, in which the concentration of a certain substance is enriched or depleted at the interface where the phases meet, e.g., air-water, liquid-liquid, solid-liquid, or solid-solid interfaces. So far as our life is concerned, liquid interfaces are much more important than other interfaces. First, the sum of the areas of various liquid interfaces relevant to us would definitely be much larger than that of other types of interfaces, as can be envisaged by thinking of various membranes in biological cells. Second, liquid interfaces, in particular, liquid-liquid interfaces are replenishable and adaptive to their environment down to the nanometer scale. This flexibility is indispensable in developing biological functions as well as in homeostasis. Furthermore, the fact that the facile mass transfer is possible on both sides of the liquid-liquid interface between the two solution phases of different solvation characters allows intricate designing of chemical reactions unique to biological systems.
