Production process

The majority of the world’s coconut shell activated carbon is produced in Sri Lanka, including raw materials sourcing and activation process. Coconut activated carbon can reach very high degrees of purity. Production includes a superheating process called pyrolysis where shells are transformed into char followed by a fluidization processes in a FBR (fluidized bed reactor) where the carbon is steam activated. The FBR consists of a rotary kiln, 20 meters long and 2.4 m in diameter in which carbon is activated at temperatures in excess of 1000 degrees Celsius (1800 F).

Various types, sizes and performance characteristics can be targeted by carefully selected raw material, activation temperature, activation time and by varying the concentration of the oxidation gases. Following steam activation, the carbon can be sorted into different granular sizes using different mesh sizes.

Production of carbon can also generate valuable bi-products such as syngas and bio-oil.

Coconut activated carbon performance

Filtration capacity and performance depends on multiple factors and carbon characteristics. Specifically, coconut shell activated carbon is known for its high levels of hardness, purity and low ash content. The production quality of the carbon is often tested against the CTS (Carbon Tetrachloride, CCl4) activity according to ASTM D3467 to ensure the proper pore volume of the the final product. Recently it has been replaced by Butane activity = CCl4 activity / 2.55.

In conjunction with CTC values, the Iodine number can be used to test the adsorption capacity in mg of adsorbed iodine per g of carbon (mg/g) and is normally the deciding performance factor in evaluating the required filtration capacity, in combination with granule mesh size, ash content and hardness.