adsorbers

An adsorber is a vessel or unit in which an adsorbent material traps contaminants from a gas or liquid by adsorption, the adhesion of molecules to the surface of the solid. Unlike absorption, where material is taken into the bulk, adsorption concentrates contaminants on the surface or within pore networks of the solid surface. Adsorbers are used to purify streams, recover solvents, remove odors, or separate components in gas streams.

Common adsorbents include activated carbon, which has a high surface area and broad affinity for organics; zeolites and other molecular sieves that provide defined pore sizes useful for size- or shape-selective separations; silica gel and alumina for drying and conditioning; and other tailored materials for specific species. Adsorption can be physical (physisorption) or chemical (chemisorption); most adsorptions in typical industrial adsorbers are physical, favored for reversibility and process cycling.

Most industrial adsorbers are fixed-bed columns packed with the selected adsorbent. To regenerate a spent adsorbent, desorption is used, typically by reducing pressure (pressure swing adsorption), increasing temperature (temperature swing adsorption), or applying vacuum (vacuum swing adsorption). The choice depends on the target contaminant, required purity, and energy considerations. Breakthrough curves describe how contaminant concentration in the effluent rises over time as the bed becomes saturated.

Applications include gas purification (carbon dioxide or sulfur compounds removal, hydrocarbon recovery), air purification (VOC removal, humidity control), and certain liquid separations. Advantages of adsorbers include high selectivity and regenerability; limitations involve adsorbent capacity, sensitivity to moisture and temperature, and the need for energy or regeneration fluids to restore performance.