Preserving the environment has since many years been an important target for anyone concerned about the future of our planet. In this context, Claude Asseau, with his broad experience in the treatment of air and water by activated carbon, decided to start his own company some thirty years ago. A new company, named ASSEAU S.A., was born. Mr. Claude Asseau is currently one of the most experienced specialists in the world of activated carbon and recognized as such by business people active in this sector. He devotes all his knowledge to his customers and the rise of the company. Most of the problems related to activated carbon have no more secrets for him. The broad technological knowledge and the implementation of activated carbon in all application fields result in putting ASSEAU S.A. at the top of companies active in this sector.
- Activated carbon is an adsorbent product obtained starting from raw materials rich in carbon (wood, peat, coal, lignite, coconut shells, fruit stones, etc.…).
- Any organic raw material containing carbon basically can be used for activated carbon production, but only a few of them turn out to be economical.
- The choice of the raw material will mostly depend on the local resources in order to ensure competitive cost prices.
- Nevertheless, the kind of raw materials used will condition the final quality of the activated carbon.
- After selection of the raw materials, they are either physically or chemically activated in an activation furnace.
- With this activation we obtain, thanks to the reaction of gas and steam, a structure of carbon.
To find the origins of carbon, we need to make a 200 to 300 millions years jump back to the end of the so called “carboniferous” primary era. The Earth was then looking like a vast greenhouse: covered with marshes and luxuriant vegetation enveloped in a hot and wet climate.
Some soils collapsed, vegetable remaining accumulated, fermented and was buried under sediments. This process, repeated many times resulted in a superposition of deposits in an atmosphere charged with carbonic gas which in turn created solid and combustible substances with a high percentage of carbon in the following chronically order: carbon, lignite and peat. These layers formed like a cluster or, more often, like veins intercalated between other sedimentary formations. The discovery of carbon is relatively recent; it was still unknown three thousand years before Jesus-Christ, whereas men already exploited the rich resources of the subsoil. According to Théophraste, the Greek blacksmiths used it as from the fourth century before our era. But it is certain that coal was already known in our country at the time of the Roman conquest. But only the Gallic exploited coal at that time. Probably also the Chinese, who knew carbon well before our era.
- This stage is necessary when producing granular or pellet carbons to transform the raw material into carbonized carbon which is the first stage to make activated carbon.
- The carbon resulting from carbonaceous raw materials is very characteristic: it is a material which has an infinity of pores (a few Angstroms) blocked by organic material.
- To be transformed into activated carbon, this carbonaceous material has to be cleaned from all these organic materials. To do so, it has to be heated at high temperature (300° C) in a revolving or vertical kiln.
There are two activation methods:
Physical process by gas: the carbon is mixed with nitrogen and steam. The organic material is then destroyed and one obtains a carbonaceous skeleton which has particular properties. The whole is heated to 700 - 1000° C according to the equation:
Chemical process: the carbonaceous material is mixed with sulphuric acid, phosphoric acid or zinc chloride and the whole is heated to 400° C with 800° C. This kind of activation is applied for powdered activated carbon.