Physicochemical Properties, Production Process and Applications of Activated Carbon

Physical Properties:

Activated carbon is a porous carbonaceous material with an abundant pore structure, exhibiting excellent adsorption properties. Its adsorption is achieved through physical and chemical adsorption forces, and its appearance is black.

Besides the main component, carbon, it also contains small amounts of hydrogen, nitrogen, and oxygen. Its structure resembles a hexagon, and this irregular hexagonal structure determines its large volume and high surface area; each gram of activated carbon has a specific surface area equivalent to over 1000 square meters.

Activated Carbon Materials:

Activated carbon is mainly made from materials with high carbon content, such as wood, coal, fruit shells, bones, and petroleum residues. Coconut shells are the most commonly used raw material. Under the same conditions, coconut shell activated carbon has the best activity quality and other special properties due to its largest specific surface area.

Production Process:

The production of activated carbon generally involves two processes. The first step is carbonization, where the raw material is dried at a temperature of 170 to 600 degrees Celsius, and 80% of its organic components are carbonized. The second step is activation. The carbonized material from the first step is fed into a reactor to react with an activating agent and steam, completing the activation process and producing the finished product. During the endothermic reaction, a combination of CO and H2 gases is mainly produced, which heat the carbonized material to a suitable temperature (800 to 1000 degrees Celsius), removing all decomposable substances and creating a rich pore structure and a large specific surface area, giving the activated carbon strong adsorption capacity. Activated carbon produced from different raw materials has different pore sizes. Coconut shell activated carbon has the smallest pore size, wood-based activated carbon generally has a larger pore size, and coal-based activated carbon has a pore size in between. Activated carbon pore sizes are generally divided into three categories: macropores: 1000-1000000 Å; transition pores: 20-1000 Å; micropores: 20 Å. Based on these characteristics, it can be seen that for different adsorption targets, appropriate activated carbon must be selected to achieve the best cost-effectiveness. Therefore, in liquid phase adsorption, activated carbon with a larger transition pore size and a larger average pore size should generally be selected.

Activated Carbon Applications

Based on its adsorption characteristics, activated carbon is mainly used to remove pollutants from water, decolorize, filter and purify liquids and gases. It is also used for air purification, waste gas recovery (such as the recovery of benzene gas in the chemical industry), and the recovery and refining of precious metals (such as the absorption of gold).

With the development of science, the uses of activated carbon are becoming increasingly widespread. As the country places greater emphasis on the ecological environment, activated carbon is playing an increasingly important role.