Activated carbon for solvents removal
In the adsorption process the polluting substances contained in the air stream are transferred on to a solid granular material with a porous surface which creates a large surface area.
The material can typically be made of carbon manufactured from either coal or coconut material and steam activated to increase the surface area.
Chemical electrical forces (van der Val) mean that once trapped on the surface of the carbon, pollutants cannot be moved unless energy is added in the form of heat (regeneration).
The regeneration to be effective may be performed on site or at a service center. This will desorb the polluntants and purified carbon so that it can be used in a new absorption cycle.
Impregnated activated carbons for acid gases
The use of activated carbons is not as effective for small molecules, such as hydrogen sulphide (H2S).
To capture these compounds with carbon, it is possible to impregnate the carbon with a basic solution which will react chemically with the hydrogen sulphide increasing the removal efficiency.
This process is called dry chemical scrubbing.
Renewable (on site) activated carbon
One of the problems associated with the use of activated carbon for the acid gas treatment is the high cost of the impregnant that is used to make the treatment of small molecules effective.
To make this technology more sustainable activated carbon has been developed that can be regenerated simply by washing with water.
Normally you can reuse the regenerated carbon for four cycles of operation. The problem with this technique depends is that the carbon is only re- generable only for particular compounds (H2S) and other compounds will remain on the carbon reducing the regenerated media life.