Activated Carbon is a term used to describe material (usually organic) that has been heated at temperatures above 600°F (315°C), or first impregnated with a strong acidic or base material and then heated at temperatures above 450°F (232°C). This treatment burns or "carbonizes" the material. Carbon has a natural affinity for organic materials which bind to its surface. The activation process creates microscopic pores that increase the surface area of each particle, giving rise to activated carbon's status as a highly reliable adsorbent.

Activated carbons are made from a wide array of organic materials, ranging from coal to peach pits. Activated carbon is available in powdered (PAC), granulated (GAC), and pellet forms. The type of activated carbon chosen will likely depend on its intended application. An activated carbon with large holes is best suited at picking up heavy organic chemicals, such as benzene, while smaller pores would catch the lighter, sometimes more gaseous pollutants.¹

Activated carbon has been historically used for removal of odor, color pigments and various catalytic functions. However, recent process advancements in the creation of activated carbon have led to more discoveries for its use. Activated carbon is now a key material in drinking water treatment, kidney filtering machine applications, cleaning waterborne industrial waste spills and in gold recovery.²

Characteristics and Challenges:

In powdered form, activated carbon is extremely fine, with an average particle size of only 20 microns and a bulk density of 21.5 lb/cu ft (34.4 kg/cu m). It is extremely aeratable, meaning the slightest air movement may cause the activated carbon powder to take flight and settle as dust. This dust fluidizes, or takes on the properties of a liquid. Activated carbon dust will coat nearly anything it lands on, including machinery, clothing and skin. In powder form, some activated carbons are capable of creating a dust explosion.

Another inherent difficulty with activated carbon is that it is insoluble with water and most solvents. Handlers must remain vigilant to prevent spills, and the intensive and costly dry-vacuuming cleanup that would follow.

Some grades of activated carbon can be degradable. If too severely damaged in the handling process, the material may lose its effectiveness as an adsorbent.

In activated-charcoal form, activated carbons typically carry an HMIS fire rating of 3, indicating high flammability in the presence of open flames, sparks, or heat. An activated charcoal blaze may reignite after the fire has been extinguished. Freshly prepared charcoal may heat spontaneously when exposed to air, and presence of water accelerates this.³