Absorbents

Many types of filter media remove unwanted chemicals from the fluid streams being filtered. For example, in home refrigerator applications, filters are required to remove odor and taste from water before it is dispensed for drinking. Absorbents are typically used to remove these types of impurities.

Absorbents are materials that target specific unwanted chemicals for removal from a fluid stream. They are usually high surface area materials that have chemical attraction for specific chemicals. Examples of absorbents are activated carbon, zeolites, and aerogels. These materials all have extremely high surface areas (in some cases, over 1000 sqm/gram), specific selectivity for certain chemicals, and the ability to remove and hold large amounts of the selected chemicals in the filter. Many absorbents are specially treated to be highly selective for the chemicals they remove and leave in the fluid to be filtered. In fact, their high surface area also supports their use as catalyst substrates.

Absorbents are used in both air and liquid applications. Because absorbents usually are used to remove odor and taste, they are used in filters that affect what we drink and breath. Typical applications for absorbents in filter media include home water filters and home HVAC filters. They are also used in automotive filters to remove unburned hydrocarbons from engines to meet government emissions regulations.

Activated Carbon Photo courtesy of Norit Americas, Inc.

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