Developing a molecular-level understanding of biochar materials using public characterization data

Biochars are black carbonaceous solids produced through biomass pyrolysis under conditions of little or no oxygen. While their properties and applications are well studied, the underlying molecular structures are poorly defined. Consequently, there has been limited computational study of biochars, despite the advantages of such techniques. In part one of this two-part study, we review the experimental techniques to characterize biochar and biochar-like materials and discuss the ambiguities, errors, and uncertainties inherent to each technique. We focus on techniques that provide chemical information and molecular-level insights, thereby adding to our understanding of the molecular structures comprising biochars. We also collect publicly available characterization data for woody biochars across a range of the highest treatment temperatures of pyrolysis. These collected data provide a quantitative description of the changes in biochar properties with increasing pyrolysis temperature. The collected data, shared as an open database, support the further development of biochar molecular models, reported in part two of this work.