CHEMICAL CHARACTERIZATION OF BIOMASS-DERIVED AND TERRA PRETA CHARS WITH PYROLYSIS MASS SPECTROMETRY

Biomass is a complex polymeric material and its thermal decomposition via pyrolysis is a multistage process that forms solid, liquid, and gaseous products with yields, carbon content, and pore structure dependent on process conditions. Transforming biomass into charcoal causes a 60-70% weight loss, rearrangement of the original sugars to aromatics, and formation of a porous and reactive carbon surface. The resulting charcoal has a variety of chemical functionalities on its surface, which also depend on feedstock and process temperature. Charcoal-like terra preta deposits, which are characterized by enhanced microbial and fungal activity, and found in both temperate and tropical climates, have been definitively linked with increased soil productivity. FTIR analysis has shown the presence of alkyl aromatic units that contain hydroxyl, carboxyl, carbonyl, ether, and lactone structures on char surfaces. We are using pyrolysis molecular beam mass spectrometry, a technique that is useful for characterizing biomolecules, to chemically characterize both naturally occurring and produced chars. Analytical results will be discussed that compare similarities and differences between natural terra preta and engineered biochars.