All about activated carbon

Activated carbon is a porous material with multiple benefits that has been tested and approved over the centuries. Obtained by carbonising and then activating a vegetable organic material, activated carbon is an adsorbent. Adsorption (different from absorption) is a physical phenomenon where a porous surface attracts and then captures polluting molecules in its pores.

Activated charcoal was already known and used in ancient Egypt, Greek Antiquity and by the Maya in Latin America for water filtration and medicine. It has been used throughout the ages, including during the First and Second World Wars, when it was incorporated into gas masks to protect soldiers from toxic gases.
Today, technological innovations have made it possible to optimise the adsorption capacities of activated vegetable carbon to make it a high-performance filtration method, particularly in water and air filtration.

Produced in powder, granule or fibre form, activated carbon follows a precise manufacturing method:
Carbonization
In an oxygen-free environment, selected organic plant material (wood bark, bamboo, coconut shells, olive pits, etc.) is calcined at high temperatures. During this process, particles of carbonised material evaporate and create pores in the charcoal. The material has become porous.
Activation
Activation removes the tar still trapped in the pores of the material. This process increases the porosity of the activated carbon and thus increases its capacity to adsorb contaminants. Thanks to this step, the adsorption surface can be between 500 and 2500m²/g! There are two methods for this: one physical and one chemical.

• Physics: Again, the coal is carbonised at a very high temperature, while inducing a thermal shock with the help of an air stream or steam.
• Chemical: Immersed in a chemical agent (e.g. phosphoric acid), the activated carbon is heated to a lower temperature and then rinsed to remove product residues.

The difference between these two methods? Physical activation forms narrow pores while chemical activation generates larger pores.

Depending on the filtration objective, the activated carbon used in HIFI FILTER® filters can take different forms:

• To neutralise odours, activated carbon particles are embedded directly in a cellulose or synthetic media. This is an impregnated media. Another possibility is the multi-layer media. A layer of activated carbon is inserted between two layers of filter media.
• In order to block vapours, hazardous substances and toxic gases, a larger quantity of activated carbon is required. A specific treatment time is also essential to ensure its effectiveness. It is mainly found in granular form or in a more compact form in filter cells.

Today, activated carbon is a real ally in our daily lives, mainly in water and air filtration. What are its different uses?

Outside industry, conventional agriculture also uses activated carbon in its cabin filters. During spraying, plant protection products produce aerosols and gases that are toxic to farm operators. In combination with a HEPA absolute filter, activated carbon helps to capture these pollutants and protect the driver.
Note that in an air filter, activated carbon can also stop :

• Smells: tobacco, food, paint, etc.
• Allergenic pollutants: pollen, animal hair, etc.
• Bacteria: moulds, fungi, etc.

All the information presented above is generic and for information purposes only. For more information, please contact us.