The main principle on which the filtration of gas molecules is based is the concept of adsorption.granular activated carbon price Two main processes by which adsorption takes place are physical adsorption and chemisorption.
- Physical adsorption is non-specific and adsorption of the gas molecule is by diffusion (Brownian Movement) or adsorption/condensation using Van Der Waals’ forces.
- The gas molecules move into an empty area and diffuse into the pore.
- Attracted and captured in the space by the Van Der Waals’ force, the molecules penetrate into the pores, impact the walls and are trapped.
- The number of pores present in the carbon is vast and therefore the total surface area is extremely large.
- The specific surface is a measure of the surface area per unit of weight, which is m2/g.
- Depending on the carbon is use and the type of filter, aggregate surface area is in the range if 2000m2/g.This represents a surface area roughly equivalent to about 4 football playing fields.dxdcarbon.com
- The physical process of adsorption is followed by chemical adsorption (chemisorption).
- This is a chemical reaction in which the two substances react together and the resultant chemical is trapped on the filter material.
- The impregnation of filter media can greatly extend the range of gases that can be removed from the air stream.