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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #411176
Research Project: Innovative Manure Treatment Technologies and Enhanced Soil Health for Agricultural Systems of the Southeastern Coastal Plain

Location: Coastal Plain Soil, Water and Plant Conservation Research

Title: Occurrence of polycyclic aromatic hydrocarbons (PAHs) in pyrochar and hydrochar during thermal and hydrothermal processes

Author
item JEON, HWANG-JU - Louisiana State University
item KIM, DONGHYUN - Kyungpook National University
item Ro, Kyoung
item LIBRA, JUDY - Leibniz Institute
item SCHEUFELE, FABIANO - Federal University Of Technology - Parana
item MARZBAN, NADER - Leibniz Institute
item CHEN, HUAN - Clemson University
item RIBEIRO, CAROLINE - Leibniz Institute
item JEONG, CHANGYOON - Louisiana State University

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2024
Publication Date: 9/6/2024
Citation: Jeon, H., Kim, D., Ro, K.S., Libra, J.A., Scheufele, F.B., Marzban, N., Chen, H., Ribeiro, C., Jeong, C. 2024. Occurrence of polycyclic aromatic hydrocarbons (PAHs) in pyrochar and hydrochar during thermal and hydrothermal processes. Agronomy. 14(9). https://doi.org/10.3390/agronomy14092040.
DOI: https://doi.org/10.3390/agronomy14092040

Interpretive Summary: In agricultural areas, biochar mad from the thermochemical conversion of biomass is one of the materials used for improving soil health. Two processes are often used to produce these carbonized solids, pyrolysis (pyrochar) and hydrothermal carbonization (hydrochar). One group of potentially toxic contaminants of concern is polycyclic aromatic hydrocarbons (PAHs). The PAHs are formed during biomass pyrolysis. We also assessed the risk of the chars by calculating the sum of the total equivalency quotient (TEQ) of the16 PAHs identified by the U.S. Environmental Protection Agency (EPA). The TEQ of hydrochars was lower than the level of pyrochar. The PAHs levels in the pyrochars and hydrochars did not exceed the limits recommended for soil amendments by both European Biochar Certificate and International Biochar initiative, except for one pyrochar.

Technical Abstract: In agricultural areas, biochar mad from the thermochemical conversion of biomass is one of the materials used for improving soil health. Two processes are often used to produce these carbonized solids, pyrolysis (pyrochar) and hydrothermal carbonization (hydrochar). One group of potential contaminants of concern is polycyclic aromatic hydrocarbons (PAHs). The range of determined PAHs were 130.74 – 9358.24, and 0-332.75 µg·kg-1 in pyrochars and hydrochars respectively. We established and assessed the risk of the chars via the sum of 16 US EPA PAHs using the toxicity equivalency factor (TEF) methodology. The calculated total equivalency quotient (TEQ) of hydrochars (0 - 21.87) is also lower than the level of pyrochar (0.13 - 61.42). Interestingly, hydrochar with the presence of excess potassium hydroxide (KOH) during the charring process has a high concentration of six-ring PAH, Indeno[1,2,3-cd]pyrene which leads to have high TEQ value. Further study is necessary to find any direct relationship between the formation of this six-ring PAH and charring parameters. Unlike previous reports, PAHs levels in the pyrochars and hydrochars did not exceed the guidelines for soil amendments by both European Biochar Certificate and International Biochar initiative, except for one farm-scale pyrochar.