Material that absorbs odors from the air or impurities from liquids. Because activated carbon fiber provides an extremely high absorption/desorption speed compared with powdered or granular activated carbon, activated carbon fiber is extensively used in the field of air and water purification, such as harmful gas removal or the recovery of Freon. Recently, new types that efficiently remove acetaldehyde and formaldehyde have been added to the product lineup, leading to even greater demand.