Activated Carbon – Production and Product Forms

The starting materials for the production of activated Carbon are:carbon-containing raw materials such as wood, peat, lignite, hard coal,fruit kernels such as olive pits, Coconut Shells, etc. The activation of these materials can be carried out using two different methods.

In gas activation, already carbonized material is used and exposed to the oxidizing influence of a gas stream, such as water vapor, carbon dioxide, air, or mixtures thereof. The activation temperature is approximately 700–1000°C, whereby the carbon is partially combusted after the water-gas reaction, thus creating a porous, highly active carbon skeleton.

In chemical activation, one usually first mixes uncarbonized, carbon-containing material with dehydrating and oxidizing chemicals. The resulting mixture is then heated to 400–800°C. The activating agents—which can include zinc chloride, phosphoric acid, sulfuric acid, and others—are subsequently washed out and recovered.

The activation itself is carried out in rotary kilns, multi-stage kilns, shaft kilns, fluidized bed kilns, or fluidized bed reactors.

The common product forms for Activated Carbon are:

shaped (mostly in the form of cylindrical pellets),

broken (granules or crushed activated carbon),

powdered in defined particle sizes.

Special manufacturing methods include:

spherical activated carbon,

activated carbon fibers or fiber mats,

so-called“honeycombs.”

The manufacturing and activation methods, as well as the underlying raw material, significantly influence the properties of the activated carbon with regard to its adsorption capacity during application. In particular, the size of the internal surface area and the pore structure are highly dependent on the activation process.