According to the different forces acting between activated carbon molecules and pollutant molecules during the adsorption process, adsorption can be divided into two categories; Physical adsorption and chemical adsorption (also known as active adsorption). During the adsorption process, when the force between activated carbon molecules and pollutant molecules is van der Waals force (or electrostatic attraction), it is called physical adsorption; When the interaction between activated carbon molecules and pollutant molecules is a chemical bond, it is called chemical adsorption. The adsorption strength of physical adsorption is mainly related to the physical properties of activated carbon, and is basically independent of the chemical properties of activated carbon. Due to the weak van der Waals force, it has little effect on the structure of pollutant molecules. This force is similar to intermolecular cohesion, so physical adsorption can be likened to condensation phenomenon. The chemical properties of pollutants remain unchanged during physical adsorption.
Due to the strong chemical bonds, which have a significant impact on the structure of pollutant molecules, chemical adsorption can be regarded as a chemical reaction, which is the result of the chemical interaction between pollutants and activated carbon. Chemical adsorption generally involves electron pair sharing or electron transfer, rather than simple perturbation or weak polarization, and is an irreversible chemical reaction process. The fundamental difference between physical adsorption and chemical adsorption lies in the forces that generate adsorption bonds.
The adsorption process is the process in which pollutant molecules are adsorbed onto a solid surface, and the free energy of the molecules decreases. Therefore, the adsorption process is an exothermic process, and the heat released is called the adsorption heat of the pollutant on this solid surface. Due to the different forces of physical adsorption and chemical adsorption, they exhibit certain differences in adsorption heat, adsorption rate, adsorption activation energy, adsorption temperature, selectivity, number of adsorption layers, and adsorption spectra.
Activated carbon is a widely used industrial adsorbent that uses charcoal, various fruit shells, and high-quality coal as raw materials. It is processed and manufactured through a series of processes such as crushing, sieving, catalyst activation, rinsing, drying, and screening through physical and chemical methods. Since its introduction in 1900, activated carbon has undergone two major events in its application process. Firstly, it was used to manufacture gas masks during World War I in the 1920s; Secondly, in the 1940s, hundreds of waterworks used activated carbon for deodorization. The adsorption capacity of activated carbon comes from its unique molecular structure. There are many pores inside the activated carbon, and the internal pores per gram of activated carbon can reach 500-1700 square meters if spread out. It is this unique internal structure that makes activated carbon have excellent adsorption capacity, and the application of activated carbon is very extensive,
Activated carbon, after high-temperature activation and special pore size adjustment technology, has a wide specific surface area and a rich pore structure that matches the molecular size of indoor harmful gases. It is specifically designed to adsorb dozens of harmful substances such as formaldehyde, benzene series, ammonia, radon, TVOC, and all harmful gases to the human body, as well as planktonic bacteria in the air. It has comprehensive functions such as odor absorption, detoxification, deodorization, dehumidification, mold prevention, sterilization, and purification. While adsorbing harmful gases, it kills pathogenic bacteria such as mold, Escherichia coli, Staphylococcus aureus, and pus, inhibits the spread of epidemic pathogens, and thoroughly eliminates indoor environmental pollution.
