Activated carbon is a kind of material with porous structure and large internal specific surface area. Because of its large specific surface area, microporous structure, high adsorption capacity and high surface activity, it has become a unique multifunctional adsorbent, which is cheap and easy to obtain and can be partially regenerated and activated. At the same time, it can effectively remove most organic matter and some inorganic matter in wastewater and waste gas, so it is widely used in environmental protection and resource recovery fields such as wastewater and waste gas treatment, air purification, rare metal and solvent recovery.
Activated carbon, like diamond and graphite, is an allotrope of carbon. As the existing form of carbon, it has a honeycomb structure and many small crystals, and its mechanism of action is adsorption. Because of its large specific surface area, many voids and pores, and strong adsorption capacity, it can adsorb pigments, toxic gases and toxic substances, and can be used for decolorization and purification of water and gas. Desorption can be achieved by heating.
Activated carbon is generally made of carbon-containing substances such as bamboo, wood and fruit, which are heated at high temperature without air, and steam is continuously introduced to remove decomposed organic substances such as water gas and wood tar.
Activated carbon is divided into granular activated carbon, powdered activated carbon and activated carbon fiber, but the utilization of powdered activated carbon is limited due to secondary pollution and cannot be regenerated and revitalized [2].
2 granular activated carbon (GAC)
85%~90% of GAC is used for water treatment and gas adsorption, and its particle size is 500 ~ 5000 μ m. Generally, the pore structure of GAC is three-dispersed, including macropores with a pore size greater than 50 nm, mesopores (transition pores) with a pore size of 2.0 ~ 50 nm and micropores with a pore size less than 2.0 nm (according to IUPAC classification).
Because of the porous structure of GAC, its adsorption speed is slow and its separation rate is not high, especially its physical form makes its application and operation inconvenient, which limits the application scope of GAC [4].
3. Application of activated carbon in daily life
Mainly use the adsorption capacity of activated carbon to purify air and water, such as masks, refrigerators, car cabs, adsorbents for water purifiers, etc. , and has a wide range of applications.