assorption

Assorption is a term encountered in some scientific writings to denote a process that combines elements of adsorption and absorption. In standard terminology, adsorption refers to the adhesion or concentration of molecules on a surface, while absorption describes penetration or uptake of molecules into the bulk of a material. Because assorption is not widely recognized as a distinct mechanism, its usage varies and it is often a misnomer for either adsorption, absorption, or a concurrent occurrence of both.

Definition and scope: In informal usage, assorption refers to uptake that involves both surface association and interior diffusion. It is often applied to porous solids or gels where solutes accumulate on external surfaces and later migrate into pores or the matrix. In such cases the uptake cannot be described by a single mechanism or isotherm.

Mechanisms: A typical assorption scenario consists of rapid surface adsorption followed by diffusion into the interior. Depending on material and solute, these steps may occur in parallel. Rate and extent depend on pore structure, solubility, temperature, and competing species.

Measurement and interpretation: Distinguishing surface and bulk contributions requires experiments such as separate isotherms, desorption studies, diffusion measurements, or spectroscopic probes. Misinterpretation is common when assorption is treated as a single mechanism.

Applications and terminology: When used, assorption should be clearly defined with explicit separation of surface and bulk processes. Otherwise, researchers should use adsorption, absorption, or sorption to avoid confusion. The concept is most relevant in porous materials, gels, and composite systems.

See also: adsorption; absorption; sorption.