The evolution of the pore structure of coconut shells during the preparation of coconut shell-based activated carbons

The pore structure of coconut shells from two sections at different stages during the preparation of coconut shell-based activated carbons were examined under scanning electron microscope (SEM). Raw coconut shells, dried shells, carbonized coconut shells and activated carbons from the same batch of coconut shells were examined. Micrographs of transverse sections of the shells showed that the pore structure of the raw material has a direct bearing on the pore structure of corresponding sections of activated carbons. The modification of the pore structure of the coconut shell was observed to begin at the drying stage and continued to the activation stage. The transverse sections of the coconut shells presented pore structures significantly different from those seen from sections of the outer surface of the same shell. This is the first time the transformations undergone by the pores of activated carbons during their preparation have been shown in micrographs. The results of this work provide insights into designing activated carbons for specialized applications in separation, purification and other operations. It is suggested, based on the observations of this work, that efforts at controlling the pore structure of coconut shell-based activated carbons should start right from the moment the raw material is harvested. (C) 2007 Elsevier Inc. All rights reserved.