Inherent organic compounds in biochar-Their content, composition and potential toxic effects

Wolfram Buss, Ondřej Mašek*, Margaret Graham, Dominik Wüst

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

143 Citations (Scopus)


Pyrolysis liquids consist of thermal degradation products of biomass in various stages of its decomposition. Therefore, if biochar gets affected by re-condensed pyrolysis liquids it is likely to contain a huge variety of organic compounds. In this study the chemical composition of such compounds associated with two contaminated, high-volatile organic compound (VOC) biochars were investigated and compared with those for a low-VOC biochar. The water-soluble organic compounds with the highest concentrations in the two high-VOC biochars were acetic, formic, butyric and propionic acids; methanol, phenol, o-, m- and p-cresol, and 2,4-dimethylphenol, all with concentrations over 100μgg-1. The concentrations of 16 US EPA PAHs determined by 36h toluene extractions were 6.09μgg-1 for the low-VOC biochar. For high-VOC biochar the total concentrations were 53.42μgg-1 and 27.89μgg-1, while concentrations of water-soluble PAHs ranged from 1.5 to 2μgg-1. Despite the concentrations of PAHs exceeding biochar guideline values, it was concluded that, for these particular biochars, the biggest concern for application to soil would be the co-occurrence of VOCs such as low molecular weight (LMW) organic acids and phenols, as these can be highly mobile and have a high potential to cause phytotoxic effects. Therefore, based on results of this study we strongly suggest for VOCs to be included among criteria for assessment of biochar quality.

Original languageEnglish
Pages (from-to)150-157
Number of pages8
JournalJournal of Environmental Management
Publication statusPublished - 1 Jun 2015
Externally publishedYes


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