Activated Carbon is a black, solid (powdered, granular or palletized) material resembling charcoal. It is an extremely porous material with a large internal surface area which accounts for its power to hold impurities, contaminants or colour bodies by a process known as adsorption. Interestingly, one kg of Activated Carbon can have a surface area of as much as 500 Acres. It is not hard to imagine enormous accumulation of impurities on such a vast area in such a small volume.

Pores in Activated Carbon have numerous sizes & shapes. Pore sizes have been classified into three types: Micropores (pore dia less than 20 nm), Mesopores (pore dia 20-200 nm) & Macropores (200 nm & above). While Micropore contribute maximum to the surface area, the meso & micropres serve as ‘roads’ & ‘streets’ leading to micropres. Since Activated Carbon is absolutely opaque and can neither be melted nor dissolved and it is not possible to subject it to various analytical techniques. We give below picture conceiving its structure:

The process of Adsorption depends on several factors like pH temperature, solvent-salute interactions, pore-size distribution etc. Performance of an activated carbon will depend on several factors like its raw material, method of activation, temperatures of carbonisation & activation etc. It is said that Activated Carbon has a ‘memory’ or ‘inheritance’.

It is, therefore, imperative that a user must try several carbons before settling for a grade. It must be kept in mind that there is no such carbon which is universally good regardless of its price. It is also equally important that the user weighs the performance of activated carbon from the angle of effect received per unit of money spent rather that per kg of carbon used.

As for regeneration of spent carbon while powdered carbons cannot be conveniently regenerated, Granular Carbons can be regenerated at temperatures above 600-700° C in specially designed furnaces. Where substantial tonnage is used, manufactures should be asked to help.

Use of Activated Carbon, particularly the powdered variety is somewhat messy but there seems to be no substitute carbon for at least in the foreseeable future.

It is very important to note that a single use of Activated Carbon may not fully exhaust its entire capacity almost one third capacity may remain unutilized. Therefore a judicious use of carbon may result in substantial savings. Details can be sent on request.