(749a) Environmental and Agronomic Utilization of Solid Pyrolysis Co-Products: Roles of Aromatic Carbon and Ionizable Functional Groups

In the past several years, environmental and agronomic utilization of solid pyrolysis co-product (charcoal, popularly called biochar soil amendment) has received considerable attention worldwide.  Ultimate goal of the land application is to reduce carbon footprint by storing char as the recalcitrant form of organic carbon in soil.  Additional claimed benefits include soil fertilization, water restoration, waste management, as well as the on-site remediation and bioenergy production.  Carboxylate functional groups of char govern its charge properties (zeta potential, point of zero charge), cation exchange capacity, hydrophilicity, and pH buffering ability.  These properties of char in turn control its interactions with the transition metals and nutrient elements as well as the formation of strong hydrogen bonds in aqueous media.  In addition, carboxyl plays critical roles in storing additional, more labile, organic carbon in soils via sorption, co-precipitation, and aggregation mechanisms.  This presentation will focus on the reaction chemistry during pyrolysis and activation of waste biomass that will result in the formation of aromatic carbon and carboxyl functionality in the solid char(coal) co-product.  Interaction mechanisms between char and soil constituents (nutrient elements, DOC, and contaminants) will be described to provide broader insights into the carbon cycles in amended soils.