What is the principle behind activated carbon filters?

What is the principle behind activated carbon filters?

The carbon filter housing is designed with a long-diameter configuration based on hydraulic simulation, and it employs high-efficiency activated carbon with an optimal particle size and a specific surface area exceeding 1,000 m²/g. This design not only provides specialized filtration at the upper layer but also delivers highly efficient adsorption at the lower layer, significantly enhancing both the purity of the treated water and the service life of the carbon media. The filter excels in removing taste and odor compounds, organic matter, colloids, iron, residual chlorine, and other contaminants in water. It also effectively reduces turbidity and color, improves water quality, and minimizes fouling of downstream systems. So, what is the operating principle of an activated carbon filter?

What is the principle behind activated carbon filters?

1. Activated carbon filters play a crucial role in dechlorination, deodorization, and the adsorption of pollutants from water.

2. Activated carbon is an amorphous form of carbon composed of numerous graphite-like layered microcrystals arranged in a disordered manner. It features crystalline defects, an exceptionally large specific surface area, and a porous structure. Based on the raw material used, activated carbon can be classified as coal-based, wood-based, shell-based, or bone-based; according to its physical form, it can be further categorized as columnar carbon, crushed carbon, powdered carbon, and fibrous activated carbon. The primary raw materials for activated carbon are carbon-rich organic substances, such as coal, wood, and fruit shells. Through activation, a complex pore structure with strong adsorption capacity is formed. Pores larger than 20,000 nanometers are classified as macropores; those between 150 and 20,000 nanometers are mesopores; and those smaller than 150 nanometers are micropores. The adsorption process in activated carbon primarily occurs within these pores and on the pore surfaces; the large number of molecules residing on the pore walls generate strong intermolecular forces that attract impurities from water and air into the pores.

3. The adsorption properties of activated carbon can be classified as physical adsorption and chemical adsorption. Physical adsorption primarily occurs in the micropores of activated carbon and is used to remove impurities from water and air. The molecular diameter of these impurities must be smaller than the pore size of the activated carbon. Different raw materials and manufacturing processes result in variations in the microporous structure, specific surface area, and pore size of activated carbon, making it suitable for different applications. In addition to carbon, the surface of activated carbon also contains functional groups that can undergo chemical reactions with the adsorbed substances, often at the interface between the activated carbon and the adsorbate. The greater the adsorption capacity of activated carbon, the better its adsorption performance.

What is the function of the carbon bed in an activated carbon filter?

The operation of an activated carbon filter is accomplished by the carbon bed. The activated carbon granules that make up the bed possess numerous micropores and a very large specific surface area, giving them strong physical adsorption capacity. As water passes through the carbon bed, organic contaminants are effectively adsorbed by the activated carbon. In addition, the amorphous regions on the surface of the activated carbon contain various oxygen-containing functional groups, which further enhance the adsorption of organic pollutants in the water passing through the bed. Activated carbon filters are widely used water-treatment equipment. When employed as pretreatment for desalination systems, they can effectively extend the service life of downstream equipment, improve effluent water quality, and prevent fouling—particularly free residual oxygen–induced poisoning of downstream reverse osmosis membranes and ion-exchange resins.