Surface functionality and porosity of activated carbons obtained from chemical activation of wood

Mixtures of wood with either phosphoric acid or diammonium hydrogen phosphate [(NH4)(2)HPO4] were heated under nitrogen or steam/nitrogen flows at temperatures between 300 and 500 degrees C. As a result of these processes, activated carbons with various pore size distribution and surface properties were obtained. The samples were characterised using potentiometric titration and sorption of nitrogen at its boiling point, The results showed the significant influence of the nature of the activating agent and the atmosphere on the final properties of the materials. It was demonstrated that steam inhibits the incorporation of heteroatoms into the carbon matrix. Activation of wood in the presence of phosphoric acid together with steam gives carbon of high surface area (similar to 1800 m(2)/g) with well-developed mesoporosity and an almost neutral surface. (C) 2000 Elsevier Science Ltd. All rights reserved.