What is the process called when a contaminant adheres to the surface of materials like silica or activated carbon?

The process where a contaminant adheres to the surface of materials such as silica or activated carbon is known as adsorption. In this process, molecules from a gas or liquid adhere to the surface of a solid or liquid, resulting in a film of the adsorbate on the adsorbent's surface. This is particularly significant in environmental and hazardous materials management, as it plays a crucial role in methods for removing contaminants from air or water by utilizing materials that have a high surface area, allowing for enhanced interaction with the pollutants.

Absorption, on the other hand, refers to a different mechanism where a substance penetrates into the bulk of another material, becoming part of its structure. Desorption is the reverse process of adsorption, where the adsorbed substance is released from the surface back into the environment. Filtration involves physically separating particles from fluids or gases using a barrier but does not specifically focus on the surface interaction that defines adsorption. Thus, the clear distinction in the mechanisms highlights why adsorption is the appropriate term for the process described.