Activated carbon filter

The adsorptive property of activated carbon is due to its highly developed pore structure. X-ray diffraction analysis shows that the specific surface area of high-quality activated carbon can be up to 1,000-3,000m²/g, including micropores with a diameter of 0.8-2nm, mesopores with a diameter of 2-50nm, and macropores with a diameter of more than 50nm. This multi-stage pore structure can effectively retain organic matter, residual chlorine and some heavy metal ions with a molecular weight of 60-300 daltons through the co-operation of van der Waals force and chemical bonding. Especially in the treatment of volatile organic compounds (VOCs), the dynamic adsorption capacity for pollutants such as benzene and formaldehyde can reach 200-500mg/g.

Modern activated carbon filters are designed with a composite structure containing a pre-treatment layer (PP cotton), a main adsorption layer (granular/powdered activated carbon), and an after-treatment layer (antimicrobial membrane). Industrial-grade units often adopt radial flow design, so that the contact time of the media through the 0.5-2mm activated carbon bed is maintained at 5-15 seconds, and the pressure drop is controlled at 0.05-0.2 MPa. The chemical adsorption of specific pollutants (e.g., hydrogen sulphide, mercury vapour) can be enhanced by surface modification technology (e.g., impregnation of transition metal oxides), and the selective adsorption efficiency can be increased by more than 40%.