While designing an adsorption system, the density of activated carbon is an important parameter as it affects the mass and volume of carbon required for a particular application. The density of activated carbon can be divided into two types.
Bulk density (also known as apparent density).
This is the mass of activated carbon per unit volume, including the voids between the particles. Bulk density depends on factors such as particle size, particle shape and degree of compaction. Granular activated carbon (GAC) typically has a bulk density of between 0.4 and 0.6 g/cm³, while powdered activated carbon (PAC) may have a slightly lower bulk density of around 0.38g-0.45g/cm3 and columnar activated carbon of 0.45g-0.65g/cm3 and granular activated carbon have essentially the same density.
True density (also known as skeletal density or solid density).
This is the mass per unit volume of activated carbon, excluding the voids between particles and the pores within the particles. True density is determined by the raw material and the activation process. The true density of activated carbon generally ranges from 2.0 to 2.2 g/cm³ (125 to 137 lb/ft³).
| Bulk density | True density |
| The mass of activated carbon per unit volume, including the voids between particles. | Mass per unit volume of activated carbon, excluding the voids between particles and the pores within the particles. |
| GAC 0.4 and 0.6 g/cm³ PAC 0.38g-0.45g/cm3 | Ranges from 2.0 to 2.2 g/cm³ |
| For estimating the mass and volume of activated carbon required | Used to determine the porosity and adsorption capacity of the carbon |