Exploring Activated Carbon: Characteristics, Preparation, and Wide Applications

In today’s environmental protection, industrial, and daily life fields, activated carbon is playing an increasingly important role. So, what exactly is activated carbon? Let’s delve deeper into this amazing material.

Activated carbon is a porous carbon – containing material that has undergone special treatment. It is usually made from carbon – containing raw materials such as wood, coal, and fruit shells through a series of complex processes including carbonization and activation. Its most prominent feature is its extremely developed pore structure and large specific surface area. The specific surface area of each gram of activated carbon can reach several hundred or even thousands of square meters. It is like a huge “molecular building” with countless tiny rooms, providing a large amount of adsorption space for various molecules.

Microscopically, the pores of activated carbon are mainly divided into micropores, mesopores, and macropores. The pore size of micropores is generally less than 2 nanometers, and it is the main place for activated carbon to adsorb small – molecule substances. The pore size of mesopores ranges from 2 to 50 nanometers, which plays an important role in the adsorption of some larger molecules and the transport of substances. The pore size of macropores is greater than 50 nanometers. Although its specific surface area is relatively small, it serves as the channel for substances to enter the internal pores of activated carbon. This multi – level pore structure enables activated carbon to effectively adsorb molecules of different sizes.

The adsorption of activated carbon is mainly based on two mechanisms: physical adsorption and chemical adsorption. Physical adsorption is caused by the van der Waals force between molecules. There is an attractive force between the pore surface of activated carbon and the adsorbed molecules, allowing the molecules to attach to the pore surface. This adsorption is usually reversible. When external conditions (such as temperature and pressure) change, the adsorbed molecules may desorb from the activated carbon surface.

Chemical adsorption is achieved through the formation of chemical bonds. On the surface of activated carbon, there may be some chemically reactive functional groups, such as carboxyl and hydroxyl groups. These functional groups can react chemically with certain specific molecules, thereby fixing the molecules on the activated carbon surface. Chemical adsorption usually has high selectivity and irreversibility.

In the physical activation method, the carbon – containing raw material is first carbonized in an inert atmosphere to obtain a carbonized material. Then, the carbonized material is activated at a high temperature with an oxidizing gas (such as steam or carbon dioxide). During the activation process, the oxidizing gas reacts with the carbon atoms in the carbonized material to form a pore structure. The activated carbon prepared by this method has a high specific surface area and a well – developed microporous structure, which is suitable for the adsorption of small – molecule substances.

The chemical activation method involves mixing the carbon – containing raw material with a chemical activating agent (such as phosphoric acid, zinc chloride, or potassium hydroxide), and then carbonizing and activating it at a certain temperature. The chemical activating agent can react with the carbon – containing raw material at a relatively low temperature, promoting the formation and development of pores. The activated carbon prepared by the chemical activation method has a more diverse pore structure, with a relatively high proportion of mesopores and macropores, which is suitable for the adsorption of large – molecule substances.

In water treatment, activated carbon is a commonly used adsorbent. It can remove organic substances, heavy metal ions, residual chlorine, and other harmful substances in water, improving the taste and odor of water quality. For example, in the tap water purification process, activated carbon filters can effectively remove odors and colors from water. In sewage treatment, activated carbon can be used as a means of advanced treatment to further reduce the concentration of pollutants in water, making the treated water meet the discharge standards.

Activated carbon also performs excellently in air purification. It can adsorb harmful gases in the air, such as volatile organic compounds (VOCs) like formaldehyde, benzene, toluene, and xylene, as well as harmful gases such as sulfur dioxide and nitrogen oxides, improving indoor and outdoor air quality. At home, activated carbon can be placed in newly renovated rooms, wardrobes, shoe cabinets, etc., to adsorb harmful gases like formaldehyde and protect people’s health. In industrial waste gas treatment, activated carbon adsorption devices can effectively remove pollutants from waste gas, reducing environmental pollution.

In the food industry, activated carbon can be used for the decolorization, deodorization, and refining of sugar solutions, oils, beverages, etc. It can remove impurities and odors from food, improving the quality and safety of food. In the pharmaceutical field, activated carbon can be used as an antidote to adsorb toxic substances in the body. In cases of drug poisoning or food poisoning, activated carbon can quickly adsorb toxins, reducing toxin absorption and buying time for treatment.

Activated carbon also has a wide range of applications in many other fields. In chemical production, it can be used as a catalyst carrier to improve the activity and selectivity of the catalyst. In the electronics industry, it can be used for electrode materials to improve battery performance. In the military field, it can be used in protective equipment such as gas masks to adsorb toxic gases and protect personnel safety.

In conclusion, as a powerful adsorption material, activated carbon plays an indispensable role in many fields with its unique structural characteristics and excellent adsorption performance. With the continuous progress of technology and people’s increasing emphasis on environmental protection and healthy living, the application prospects of activated carbon will be even broader. It is believed that in the future, activated carbon will bring more surprises to our lives and social development.