Scanning Electron Microscopy as a Potential Tool for Distinguishing Charcoal from Dark, Oxidized, Biomass

Authors

• João Vitor dos Santos, Old Dominion UniversityFollow
• Aleksandar I. Goranov, Old Dominion UniversityFollow
• Lais Gomes Fregolente, Brazilian Center for Research in Energy and Materials
• Joao Marcos de Lima-Faria, Brazilian Center for Research in Energy and Materials
• Diego Stefani Teodoro Martinez, Brazilian Center for Research in Energy and Materials
• Patrick G. Hatcher, Old Dominion UniversityFollow

Document Type

Article

Publication Date

2026

DOI

10.1021/acs.estlett.6c00241

Publication Title

Environmental Science & Technology Letters

Volume

13

Issue

8

Pages

1092-1100

Abstract

Condensed aromatic carbon (ConAC) is widely used as a proxy for organic materials derived from biomass burning. However, recent evidence shows that ConAC can be also formed through nonpyrogenic oxidative processes. This study presents a proof-of-concept investigation using scanning electron microscopy (SEM) to distinguish charcoal from dark, ConAC-rich materials produced by ambient oxidation of biomass. Pine wood exposed to long-term iron-mediated oxidation was compared with unaltered wood and a controlled laboratory-generated charcoal reference. Conventional geochemical analytical methods, including benzenepoly(carboxylic acid) (BPCA) analysis, Fourier transform–ion cyclotron resonance–mass spectrometry (FT-ICR-MS), solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis, confirmed substantial nonpyrogenic formation of ConAC in the oxidized wood. SEM imaging revealed that the oxidized biomass retained the native wood cellular features, including secondary wall layering and compound middle lamella, closely resembling unaltered wood. In contrast, the charcoal reference exhibited collapsed and homogenized cellular microstructures. These clear morphological differences between the different formation pathways suggest that microstructural preservation may serve as a useful diagnostic indicator for differentiating pyrogenic and nonpyrogenic charcoal-like materials. Thus, incorporating SEM-based screening alongside geochemical analyses can potentially improve source attribution of ConAC and refine interpretations of fire history and refractory carbon cycling in environmental systems.

Rights

© 2026 The Authors.

This article is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) License.

Original Publication Citation

dos Santos, J. o. V., Goranov, A. I., Fregolente, L. G., Lima-Faria, J. o. M. d., Martinez, D. S. f. T., & Hatcher, P. G. (2026). Scanning electron microscopy as a potential tool for distinguishing charcoal from dark, oxidized biomass. Environmental Science & Technology Letters, 13(8), 1092-1100. https://doi.org/10.1021/acs.estlett.6c00241

ORCID

0000-0002-6954-4810 (dos Santos), 0000-0002-5103-0838 (Goranov), 0000-0002-1606-1305 (Hatcher)

Repository Citation

dos Santos, João Vitor; Goranov, Aleksandar I.; Fregolente, Lais Gomes; Lima-Faria, Joao Marcos de; Martinez, Diego Stefani Teodoro; and Hatcher, Patrick G., "Scanning Electron Microscopy as a Potential Tool for Distinguishing Charcoal from Dark, Oxidized, Biomass" (2026). Chemistry & Biochemistry Faculty Publications. 395.
https://digitalcommons.odu.edu/chemistry_fac_pubs/395