Introduction of activated carbon | What is Activated Carbon?Specifically-adjusted activated carbon
Activated carbon has micropores, which are classified as follows.
When measurement method of pore distribution differs, the classification can be confusing.
Classification specified by IUPAC (International Union of Pure and Applied Chemistry) is as shown below.
| microporous | Related to adsorption of pores of diameter 20Å or less |
|---|---|
| mesoporous | Related to adsorption of pores of diameter 20 – 500Å |
| microporous | Related to adsorption speed of pores of diameter 500Å or more |
Kuraray adjusts micropore diameter and pore volume when producing activated carbon to apply special functions to produce high added value activated carbon, which is a special technique of Kuraray.
Carbon Molecular Sieves (CMS)
Generally, CMS are used in gas phase. Several types of mixed molecules are passed through the activated carbon layer for separation.
CMS separate air by narrowing the entrances of the pores and using differences in adsorption speed of oxygen molecules (3.9 × 2.8Å) and nitrogen molecules (4.0 × 3.0Å).
There are a few manufacturers worldwide, and Kuraray is one of the top makers.
Activated carbon for vehicle canisters
Activated carbon for vehicle canisters is used for the following systems. Gasoline vapor exhaust from vehicles or gasoline stations is collected with activated carbon and desorbed with clean air taken in during driving of the vehicle and combusted.
As adsorption and desorption are repeated for activated carbon in this use, it has a special pore distribution.
Kuraray entered this field in the early days in Japan. Kuraray’s history of engineering and development is the longest and its quality and quantity are top in Japan.
Activated carbon for solvent recovery
Similar to the above-mentioned activated carbon, this type of activated carbon is also used for processed with repeated adsorption and desorption. Therefore, it has a special pore distribution for each solvent to facilitate high adsorption and reduced energy for desorption.
Care is taken to avoid changes in the nature of the solvent due to the catalytic action of the activated carbon.
Activated carbon for water treatment
As various materials must be adsorbed, the pore distribution is adjusted according to the target material. Activated carbon with small pores is used for deodorizing and dechlorination of waterworks, while that with large pores is used for effluent treatment.
Activated carbon for decoloring of recyclable chemicals
Activated carbon for decoloring in liquid phase must have large pores.
Kuraray produces activated carbon with thin (low concentration) pores (KURARAY COAL™ GLC) for recyclable chemicals (after desorption with rare sodium hydroxide solution, and neutralizing with dilute hydrochloric acid).
Impregnated activated carbon
Impregnated activated carbon has special characteristics by impregnation with specific chemicals or metals.
Examples of impregnated materials are as follows:
| Chemicals | Adsorption of acid, basic or aldehyde gas, and others |
|---|---|
| Metals | Antibacterial action in water, removal of ethylene, oxidation of organic matter, and deodorization |
| Mixture with ceramics | Prevention of ignition of the activated carbon |
| Others |