The procedure for processing activated carbon typically consists of
a carbonization followed by an activation of carbonaceous material
from vegetable origin.
Carbonization is a heat treatment at 400-800°C which converts raw
materials to carbon by minimizing the content of volatile matter
and increasing the carbon content of the material. This increases
the materials strength and creates an initial porous structure
which is necessary if the carbon is to be activated.
Adjusting the conditions of carbonization can affect the final
product significantly. An increased carbonization temperature
increases reactivity, but at the same time decreases the volume of
pores present. This decreased volume of pores is due to an increase
in the condensation of the material at higher temperatures of
carbonization which yields an increase in mechanical strength.
Therefore, it becomes important to choose the correct process
temperature based on the desired product of carbonization.
Carbonization
The carbonization process involves heating the selected raw
material in the absence of oxgen. This step drives of volatile
components, such as water and parlaying behind carbon-rich char.
The carbonization process can take place in rotary kilns, retorts,
or other specialized equipment.
Activation
The activation process is crucial for creating the porous structure
of activated carbon. There are two main methods of activation,
a. Physical Activation: ln physical activation. the carbonized char is heated to high
temperatures (800-1000 degrees Celsius and treated with gases like
steam or carbon dioxide. This process creates pores by causing the
char to shrink and develop cracks.
b. Chemical Activation: in chemical activation, the carbonized char is impregnated with a
chemical activating agent, typically an alkali metal hydroxide or
phosphoric acid. The impregnated char is then heated to moderate
temperatures 500-800 degrees Celsius, resulting in the development
of porous structure.
Washing and Drying
The activated carbon is washed thoroughly with water to remove any
residual impurities or chemical residues.The washing process may
involve multiple stage sand filtrations. After washing, the
activated carbon is dried to remove excess moisture.
Sizing and Packaging
The dried activated carbon is crushed, miled, or ground to achieve
the desired particle size distribution. the activated carbon may
undergo additional Drocessine steps, such as silevine or
peletizine. to optain specic palice sizes or shapes, finally the
activated carbon is packaged and prepared for distribution.
