Water Treatment Products

Activated carbon, also called activated charcoal, is a form of carbon that has been processed with steam to create a vast number of tiny pores between the carbon atoms. This increases the surface area of the substance to as much as 1500 square meters per gram. One kilogram of activated carbon has the surface area equivalent to many football fields. The increased surface area of activated carbon makes the material suitable for adsorption, a process by which impurities in substances such as fluids, vapors, or gas are removed.

Impure molecules are held within the carbon’s internal pore structure by electrostatic attraction or chemisorption. The adsorption process helps carbon reduce dangerous matter, activate chemical reactions, and act as a carrier of biomass and chemicals. Activated carbon is usually made from wood, peat, or coconut shells. There are over 150 grades of activated carbon, each with its own uses and applications. Commercially, there are three major product groups:

Powdered activated carbon; particle size 1-150 μm
Granular activated carbon, particle size 0.5-6 mm
Extruded activated carbon, particle size 0.8-6 mm

The pore size distribution is highly important for practical application. Ideally, the carbon material used should have a pore structure that is larger in size than the material it is trying to adsorb. The best fit depends on the compounds of interest, the matrix (gas or liquid), and treatment conditions. According to the International Union of Pure and Applied Chemistry, there are three distinct groups of pores:

Macropores (> 50 nm diameter)
Mesopores (2-50 nm diameter)
Micropores (< 2 nm diameter)

Micropores generally contribute to the major part of the internal surface area. Macro and Mesopores can generally be regarded as the highways into the carbon particle, and are crucial for kinetics. Macropores can be visualized using scanning electron microscopy.