Technology for the preparation of activated carbon

Activated carbon is a specially treated charcoal in which organic raw materials are heated under air-isolated conditions to reduce the non-carbon components, which then react with gases and the surface is eroded to produce a microporous developed structure. Activated carbon has a wide range of applications and it is, therefore, important to understand some of the techniques used to prepare activated carbon.

Here is the content list:

l Preparation of activated carbon by chemical activation

l Activated carbon preparation by physical activation

Preparation of activated carbon by chemical activation

The chemical activation method is to prepare activated carbon by mixing various raw materials containing carbon with chemicals evenly and then, at a certain temperature, going through the process of carbonization, activation, recovery of chemicals, rinsing, and drying. Phosphoric acid, zinc chloride, potassium hydroxide, sodium hydroxide, sulphuric acid, potassium carbonate, polyphosphate, and phosphate esters can be used as activation reagents. Although the chemical reactions occur differently, with some having an erosive, hydrolytic, or dehydrating effect on the raw material, and some acting as oxidizers, these chemicals can all have a beneficial effect on the activation of the raw material, with the most commonly used activators being phosphoric acid, zinc chloride, and potassium hydroxide. Chemical activators can inhibit the formation of tar by-products and prevent tar from blocking the fine pores generated during pyrolysis, which can improve the yield of activated carbon.

Activated carbon preparation by physical activation

The physical activation method, also known as gas activation, involves contacting the charred raw material with an activating gas such as water vapor, flue gas, CO, or air at a temperature of 800-1000°C. The basic process is mainly based on the use of a gas activator. The basic process of the physical activation method consists of carbonization, activation, decontamination, crushing, and refining, with a clean preparation process and little liquid phase contamination.

During the preparation process, the disordered carbon atoms and miscellaneous atoms of the high-temperature activation gas with oxidation properties first react to open the originally closed pores, and then the basic microcrystalline surface is exposed. Then the activation gas continues to react with the carbon atoms on the basic microcrystalline surface with oxidation, which causes the pores to expand continuously. Some unstable carbon is gasified to produce CO, CO2, H2, and other carbon compound gases, thus creating new pores, while tar and uncharred compounds are also removed, resulting in an activated carbon product. The well-developed specific surface area of the activated carbon is then derived from the increased pore capacity of the mesopores and macropores, and the interconnected penetration of the formed macropores, mesopores, and micropores. As the physical process is relatively simple, the waste gas produced is mainly CO2 and water vapor, which is less polluting to the environment, and the final activated carbon product has a high specific surface area, a well-developed pore structure and a wide range of applications, over 70% of activated carbon manufacturers worldwide use the physical process to produce activated carbon. The carbon activation process generates a large amount of waste heat, which can be used for drying raw materials, making high-temperature steam in waste heat boilers, washing and drying products, etc.

There are more activated carbon preparation technologies waiting to be discovered, if you want to know more about activated carbon, you can pay attention to Jiangsu PURESTAR Environmental Protection Technology Co., Ltd.