Characterization of activated carbons derived from short rotation hardwood pyrolysis char

Chars from fast and flash pyrolysis of different short rotation hardwoods are activated by steam or KOH, resulting in a variety of activated carbons (ACs). Analysis of nitrogen adsorption isotherm shows that microporous ACs are obtained. Density functional theory calculation is applied to obtain information concerning the micropore size distribution. Additionally, methylene blue (MB) and iodine adsorption experiments are performed to evaluate the AC adsorptive properties. The textural and adsorptive properties are compared with a commercial AC (Norit). KOH activation yields ACs with very high surface area, micropore volume and adsorption capacity, while steam activation promotes formation of narrower micropores but yields less pore volume. The MB adsorption kinetics can be described by the pseudo-second-order model, and most ACs adsorb at least 70% of their maximum MB adsorption capacity within 15 min.

► Short rotation hardwoods are pyrolysed, and the obtained pyrolysis chars are activated. ► KOH activation promotes very large surface area development. ► Steam activation promotes narrower micropores than KOH. ► Nitrogen, methylene blue and iodine adsorption tests indicate practical applicability of ACs. ► Kinetic study indicates very fast adsorption process for most ACs.