Is the particle size of GAC and PAC classified based on the type of activated carbon that it have been made from, or is there any standard particle size that have been regulated for all types of activated carbon generally? Is there any reference you can recommend?
Granular means particles a few mm big, typically, whereas powder means particle sizes of tens to hundreds microns. I am not aware than a classification exists based on size. I feel that granular AC is as-produced from the raw material (e.g. pieces of wood), whereas powder suggests that an additional grinding step has been used.
Alain
Generally granular activated carbon has a relatively larger particle size compared to powdered activated carbon and consequently, presents a smaller external surface. Diffusion of the adsorbate is thus an important factor. These carbons are suitable for adsorption of gases and vapors, because they diffuse rapidly. Granulated carbon are used for water treatment, deodorization and separation of components of flow system and is also used in rapid mix basins. GAC can be either in granular or extruded form. GAC is designated by sizes such as 8×20, 20×40, or 8×30 for liquid phase applications and 4×6, 4×8 or 4×10 for vapor phase applications. A 20×40 carbon is made of particles that will pass through a U.S. Standard Mesh Size No. 20 sieve (0.84 mm) (generally specified as 85% passing) but be retained on a U.S. Standard Mesh Size No. 40 sieve (0.42 mm) (generally specified as 95% retained). AWWA (1992) B604 uses the 50-mesh sieve (0.297 mm) as the minimum GAC size. The most popular aqueous phase carbons are the 12×40 and 8×30 sizes because they have a good balance of size, surface area, and head loss characteristics.
Hi Nad, both Shameran and Dr Celzard have given clear explanations.
The particle size of GAC and PAC is not classified based on the type of activated carbon that it comes from. The sizes depends on the manufacturer and the end user.
Typical sizes have been mentioned by Shameran.
You may want to read up from Activated Carbon from producers such as
Calgon, Norit, Green Activated Carbon Sisters Group, Chemviron Carbon, Continental Carbon Group, CARBOCHEM INC. etc
In process industrial use, often granular AC is preferred due to better flow characteristics for granular AC as compared to PAC.
The main important character in PAC or GAC is the surface area which gives high efficiency in adsorption mechanisms . you can refer to my paper titled removal of phenol and mcresol from petroleum wastewater using AS and PAC.
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