PREPARATION OF ACTIVATED CARBON FROM COCONUT SHELL IN A SMALL SCALE COCURRENT FLOW ROTARY KILN

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Abstract
Activated carbons were prepared at 800°C in a small scale rotary kiln fed either with fresh or precarbonized coconut shell, employing a mixture of steam and air, flowing cocurrently. Typical product rates obtained were 0.2 and 0.6g/min for fresh and precarbonized shell respectively. Product surface area increased with increasing water input concentration from about 0.5 to 5 g H2O/g feed, resulting in values up to about l,400m2/g. The use of N2 instead of air during activation did not significantly change product surface area. It was demonstrated that both carbonization and activation of the coconut shell can be carried out together in a single heating step, resulting in a higher overall yield than if carried out with the usual two steps procedure. The morphology of the carbons produced consisted of micropores <10 Å width which afforded most surface area, and of macropores, some of them resembling the skeletal structure of the raw material.