The so-called regeneration is to recover the function of activated carbon which has lost or some of its adsorption ability, so as to be used in the process of adsorption operation from scratch. The choice of regeneration method depends on the type of activated carbon and the nature of adsorbent. That is to say, the types of adsorbents of activated carbon are different, the amount of adsorbents is different, and the regeneration methods of activated carbon are also very different. Together, considering from the aspects of economy and environmental protection, the focus of attention is to select appropriate regeneration methods for users with large usage, because regeneration is related to reducing costs, saving capital and protecting the environment.
Regeneration methods can be divided into two categories: heating regeneration and non-heating regeneration.
Heating regeneration
1. Hot air regeneration - using air as desorption carrier, for example, to recover halogen solvents.
2. Water vapor regeneration - low boiling point solvent uses general vapor, high boiling point solvent uses superheated vapor.
3. Recycling of inert gas. Activated carbon adsorbed is usually purged with nitrogen to desorb it.
4. Calcination and regeneration - Organic matter is oxidized to carbon dioxide under high heat.
5. Microwave regeneration - Activated carbon is a strong absorbent microwave material. Microwave irradiation rapidly warms up and makes organic matter transpire.
6 light regeneration - combining semiconductor photocatalytic technology with activated carbon regeneration, using photocatalytic degradation of adsorbate to rehabilitate the adsorption function of activated carbon, achieving green, pollution-free in-situ regeneration of activated carbon. Northeast Forestry University of China has carried out research work in this field and obtained certain role.
In addition, there are flue gas regeneration, Infrared Regeneration and sand regeneration as heat transfer medium.
Heating regeneration is a common method of regeneration, especially for carbon used in water treatment. Its regeneration technology is as follows:
The process is as follows:
Dry - heat to 100 - 150 C to transpire water in activated carbon and some low boiling point organic matter;
Carbonization - When heated to 300 - 700 C, some organic matter is transpired or differentiated, and some organic matter is carbonized and left in activated carbon.
Activation --- heating to over 700 C, so that carbon and activated gas remaining in activated carbon react, escaping the generated gaseous products, from the original pore formation; cooling --- quenching after activation to prevent oxidation.
