Mesoporous activated carbon from agricultural byproducts

Several different activated carbons have been prepared, from olive stones, solvent-extracted olive pulp and peach stones. Both a two-step procedure, c arbonization followed by steam activation, and a single-step procedure, car bonization and activation in a single stage, have been applied at temperatu res from 770 to 850 degreesC. The effect of such variables as heating rate during carbonization and activation, final temperature, soaking time and st arting material, on the development of pore structure, have been investigat ed. Porosity and surface area have been evaluated by adsorption of nitrogen at 77 K. Mesoporosity and macroporosity were determined by mercury porosim etry. Scanning electron microscopy and X-ray diffraction analysis revealed useful information on the surface texture and structure respectively. Two-s tep physical activation of olive stones, with steam, yielded mesoporous str uctures. Extended time of activation favoured mesopore development. The par ent olive stones showed the most homogeneous surfaces. All the activated ca rbons prepared were amorphous. Their well-developed porosity and large surf ace area combined with their chemical composition render the activated carb ons from agricultural by-products an attractive product.