The coconut shell charcoal is fed into the rotary kilns normally activated by steam at a igh tempreature abouve 900° C - 1100° C resulting and expanding the internal surface area of the pores creating more sites for adsorption.
The resultant big particle are then crushed and sieved to get the desired particle with sizes ranging from 0.2 to 5mm.
Three main forms of activated carbon are,
Granular Activated Carbon - Irregular shaped particles with sizes ranging from 0.2 to 5 mm.
Powder Activated Carbon - Carbon with a size predominantly less than 0.21mm (70 US mesh)
Pelleted Activated Carbon - Extruded and cylindrical shaped with diameters from 0.8 to 5 mm.
Three groups of pores can be distinguished in Activated carbon
• Micro pores having radius less than 1nm
• Meso pores having radius 1 - 25nm
• Macro pores having radius greater than 25nm