What Is Granular Activated Carbon?

Of the various commonly-available forms of activated carbon, granular activated carbons is perhaps the most widely used and versatile.

What is Granular Activated Carbon?

Granular activated carbon, often abbreviated to GAC, is high purity form of carbon characterised by its vast surface area and is used in many purification applications in both the liquid and gas phase.  Particle sizes of the granules typically range from around 0.2mm up to 5mm, the choice of ‘mesh size’ depending on the desired end-use for the material.  Particles smaller than 0.2mm are generally classified as powder activated carbon (or PAC).  The other main physical form of activated carbon is the extruded pellet, which offers a uniform cylinder of carbon, normally 3 or 4mm in diameter.

Granular activated carbon is typically manufactured from bituminous coal, coconut shells or certain types of wood.  Each raw material results in a granular activated carbon with slightly different physical properties, in terms of purification performance, so the choice is again driven by the end-user the customer has in mind.

How does Granular Activated Carbon Work?

The surface of granular activated carbon is made up of microscopic holes and channels, known as pores, only visible under a suitably powerful microscope.  It is these pores that result in its huge surface area – the statistic often quoted is that a teaspoon of granular activated carbon has the same surface area as a football pitch!

When a contaminated fluid passes through a filtration device containing granular activated carbon, the impurities are trapped within these pores in a process called adsorption, allowing the purified fluid to pass through. Typical applications for granular activated carbon include the removal of taste, odour and colour from drinking water, as well as traces of other dissolved contaminants such as pesticides and herbicides.

One of the key advantages with using granular activated carbon for fluid purification, rather than powder activated carbon, is that granular activated carbon can be recycled for reuse via a process called thermal reactivation.  Carbon that is spent, ie the pores are filled with contaminants so that the treatment objective is no longer being achieved, can be passed through a high temperature kiln.  The contaminant molecules are forced out of the pores and destroyed, leaving a reactivated granular activated carbon ready to be used again and again in the customer’s process.

For more information about activated carbon, please contact email: support@drccarbon.com