Physico-Chemical Characteristics of Carbonized Biomass Prepared by Different Methods.

Twelve black carbon samples prepared from various source materials by fast pyrolysis, slow pyrolysis, and hydrothermal conversion methods and three samples isolated from coal or wood fly ashes were characterized for their cation and anion exchange capacities, pH, moisture holding capacity, specific surface, free-radical content, C functional groups, resistance to oxidation, crystallinity, and microscopic morphologies. A wide range in properties was observed, and were largely correlated with method of preparation rather than source material.   These results indicate that careful consideration needs to be given to the specific properties of each black carbon before using it as a soil amendment.  In general, black carbon produced by slow pyrolysis and hydrothermal conversion was suitable for soil amendment.  For black carbon produced by most fast pyrolysis methods, additional processing to increase cation exchange capacity, lower pH, and increase moisture-holding capacity is recommended before application to soil.