sorbent

A sorbent is a material that can attract and hold another substance from a gas, liquid, or solution, a process collectively known as sorption. The substance being taken up is called the sorbate, while the material that does the taking up is the sorbent. Sorption can occur on surfaces (adsorption) or within the bulk of the material (absorption). Some processes involve both, and sorption may be physical (physisorption) or chemical (chemisorption), with the latter involving bond formation.

Sorbents are chosen for high surface area and porosity, chemical compatibility with the sorbate, mechanical strength, and selectivity. Common sorbents include activated carbon, silica gel, alumina, zeolites, clays, and polymeric resins. Physical sorbents rely mainly on van der Waals forces or capillary condensation, while chemical sorbents react with the sorbate to form new compounds. Pore structure is described as micro-, meso-, or macroporous, influencing capacity and diffusion.

Applications span environmental, industrial, and consumer uses. In environmental cleanup, sorbents remove organic pollutants, metals, and moisture from air and water, or recover solvents in batch or flow systems. In gas processing, zeolites and activated carbons provide drying and selective adsorption. Sorbents also serve as catalyst supports, detergents with desiccant properties, and humidity control in packaging. Regeneration by heating, pressure swing, or solvent washing allows reuse, while spent sorbents may require appropriate disposal as waste.