Water pollution has become a common concern for countries around the world. People have applied various materials to water treatment research to seek more effective methods to improve water quality and drainage, and reduce pollution. However, in recent years, with the increasing number of pollutants and the complexity of pollutant components, conventional water treatment methods can no longer meet the requirements, and deep treatment is necessary. Some single-function materials and methods are no longer applicable. Therefore, activated carbon (AC), which is widely available, easy to regenerate, and can be repeatedly used, has gained widespread application. Its strong adsorption capacity and good mechanical strength make it not only suitable for direct use as an excellent adsorbent in water treatment, but also suitable for use in combination with other materials as a catalyst and catalyst carrier.
Activated carbon is an amorphous carbon with many layered microcrystalline structures that are irregularly assembled, with crystal defects. These internal structures make activated carbon not only adsorbent but also catalytic in water treatment. Activated carbon has countless microscopic pores that are interconnected, with pore diameters ranging from 1×10-10 to 1×10-6 meters, with particularly many pores in the range of 1×10-10 to 1×10-9 meters. This gives activated carbon a huge specific surface area (up to 1000 m2/g). These physical properties are also one of the reasons why activated carbon has a strong adsorption capacity. [1] The size of activated carbon's adsorption capacity is not only related to its own properties but also to the molecular structure, solubility, and ionization degree of the adsorbed substance.
Activated carbon is divided into powder activated carbon (PAC) and granular activated carbon (GAC) according to its shape. At present, the liquid phase adsorption such as purifying decolorization and water treatment is mostly carried out by powdered activated carbon in intermittent contact mode. Granular activated carbon is also often used in water treatment, and in liquid phase adsorption, granular activated carbon is mainly used for fixed bed, moving bed and flowing bed treatment.
In the purification of water supply, activated carbon not only has a good effect on color and smell removal, but also has a high adsorption capacity for synthetic detergent. The use of activated carbon to remove most organic matter in water is one of its important applications. In addition, activated carbon can effectively remove carbamate pesticides and COD, Mn and so on, which can hardly be decomposed. Because activated carbon can effectively remove free chlorine and some heavy metals (such as mercury, antimony, tin, chromium, etc.) from water, and is not easy to produce secondary pollution, it is also often used in the purification process of household water and drinking water.
In the treatment of industrial wastewater, activated carbon is mainly used as the final advanced treatment. For petrochemical and printing and dyeing wastewater with high COD and BOD content, activated carbon can also be used for secondary treatment combined system. Due to the wide variety of drugs and the complexity of wastewater components, the corresponding wastewater treatment methods are also very different. In most cases, several treatment processes need to be combined, and activated carbon is often used in the final advanced treatment in the combined process. Activated carbon can be combined with different materials to form a new process technology to achieve better treatment results. For example, ozone-biological activated carbon (O3-BAC) wastewater reuse technology.
