Occurrence of Polycyclic Aromatic Hydrocarbons (PAHs) in Pyrochar and Hydrochar during Thermal and Hydrothermal Processes
Hwang-Ju Jeon,
Donghyeon Kim,
Fabiano B. Scheufele,
Kyoung S. Ro,
Judy A. Libra,
Nader Marzban,
Huan Chen,
Caroline Ribeiro,
Changyoon Jeong
Affiliations
Hwang-Ju Jeon
Red River Research Station, Louisiana State University Agricultural Center, 262 Research Station Dr., Bossier City, LA 71112, USA
Donghyeon Kim
Department of Integrative Biology, Kyungpook National University, Daegu 41566, Republic of Korea
Fabiano B. Scheufele
Leibniz Institute for Agricultural Engineering and Bio-Economy e.V. (ATB), Max-Eyth-Allee 100, 14469 Potsdam, Germany
Kyoung S. Ro
Coastal Plains Soil, Water & Plant Research Center, United States Department of Agriculture (USDA) Agricultural Research Service (ARS), 2611 W. Lucas St., Florence, SC 29501, USA
Judy A. Libra
Leibniz Institute for Agricultural Engineering and Bio-Economy e.V. (ATB), Max-Eyth-Allee 100, 14469 Potsdam, Germany
Nader Marzban
Leibniz Institute for Agricultural Engineering and Bio-Economy e.V. (ATB), Max-Eyth-Allee 100, 14469 Potsdam, Germany
Huan Chen
Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC 29634, USA
Caroline Ribeiro
Leibniz Institute for Agricultural Engineering and Bio-Economy e.V. (ATB), Max-Eyth-Allee 100, 14469 Potsdam, Germany
Changyoon Jeong
Red River Research Station, Louisiana State University Agricultural Center, 262 Research Station Dr., Bossier City, LA 71112, USA
Pyrochar (Biochar) produced from the thermochemical conversion of biomass has been widely used as a soil amendment to improve agricultural soil quality. Since polycyclic aromatic hydrocarbons (PAHs) can be produced in such processes, the occurrence of PAHs in pyrochars has been extensively studied, and standards such as the European Biochar Certificate (EBC) and International Biochar Initiative (IBI) contain limit values for biochars applied to soils. However, studies on PAH levels in hydrochars from hydrothermal processes, which can be an alternative to wet biomass are scarce. This study focuses on comparing the occurrence of 16 PAHs regulated by the US EPA in 22 char samples (including pyrochars from pyrolysis, hydrochars from hydrothermal carbonization, and, for the first time, hydrothermal humification) using an ultrasonic extraction method. Results showed that the sum of the 16 EPA PAHs in all samples was well below the requirements of the two standards, except for pyrochar produced at the farm scale. They ranged from 131 to 9358 µg·kg−1 in the seven pyrochars and from not detected to 333 µg·kg−1 for the fourteen hydrochars. Our findings indicate that hydrochar produced via hydrothermal methods exhibits much lower concentrations and is a safe option for soil amendment and environmental applications.
