Carbon filters work on the principle of carbon filtering, which is the process that uses a bed of activated carbon to eliminate impurities and contaminants, through chemical absorption. Every particle or the granule of carbon gives a big pore structure or a large surface area, enabling contaminants the highest possible exposure to the active spots in the filter media. One pound of activated carbon has a surface area of around 100 acres.
Activated carbon in the carbon filter works through the process named adsorption, whereby the pollutant molecules present in the liquid to be treated are inside the carbon substrate’s pore structure. Carbon filter is generally used for the water purification, industrial gas processes and air purifiers. The industrial application includes the elimination of hydrogen sulfide and siloxanes from biogas. It is also utilized in a number of other kinds of applications like respirator masks, purification of sugarcane and in the recovery of valuable metals, in particular gold. It is also seen in a cigarette filters.
As far as the kinds of carbon filters are concerned, there are two major types that are generally seen in the filtration industry. The one is powdered block filters and another is granular activated filters. Generally, the carbon V-Bank filters are more efficient for eliminating a higher number of impurities or contaminants, based on the higher surface area of carbon. A number of carbon filters also use any secondary medium like silver for example, so as to prevent any bacterial growth inside the filter. As an alternative, the activated carbon itself might be coated with metals like silver to provide it this bacteria resistance property. Hence, the need of secondary medium is eliminated. Carbon filters are considered the oldest filters being used since thousands of years, and they were previously used just for water purification.