which a contaminant in water or air is adsorbed onto a solid material. Adsorption is used for off-gas control , groundwater remediation, landfill leachate treatment, industrial wastewater treatment, and water treatment for drinking or industrial purposes. The most commonly used adsorbent is granular activated carbon (GAC). GAC has a tremendous amount of surface area per mass, on the order of one thousand square meters per gram. Its surface attracts many organic compounds; thus, a small amount of GAC can adsorb a significant amount of organic material. GAC may be regenerated, during which contaminants are destroyed.

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