Molecular compounds present in biochar carbon structure are studied from biochar produced from forest, food, and agricultural wastes and sewage sludge using pyrolysis gas chromatography mass spectrometry (Py-GC/MS). The results show that with increasing biochar production temperature (PT), the total pyrolysis yield decreases, and the macromolecular structure becomes more condensed with the aromatic linkages becoming less alkylated, hence indicating a stable carbon structure. These highly stable biochar samples consist predominantly of inertinite and have the entire random reflectance (R) distributions above the inertinite benchmark (IBR2%). The results are aligned with high carbon stability of high-temperature biochar. In contrast, biochar samples that were insufficiently carbonized and comprised of mainly semi-inertinitic biochar contain alkane traces, volatile compounds, and higher degrees of alkylation with aromatic linkages in their molecular structure. This indicates the more proneness to oxidative and microbial breakdown, and therefore a less condensed and less stable carbon structure. Additionally, occurrence of these compounds in inertinitic biochar indicate retention of free hydrocarbons within the biochar carbon structure. Complimenting microscopic and bulk geochemical data, Py-GC/MS data is additionally advantageous to assess the stability conditions of the biochar samples.

中文翻译：

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生物炭的分子表征及其与碳永久性的关系


使用热解气相色谱质谱法 (Py-GC/MS) 对森林、食品、农业废物和污水污泥中产生的生物炭研究生物炭碳结构中存在的分子化合物。结果表明，随着生物炭生产温度（PT）的升高，总热解产率降低，大分子结构变得更加稠密，芳香键烷基化程度降低，从而表明碳结构稳定。这些高度稳定的生物炭样品主要由惰性体组成，并且整个随机反射率 (R) 分布高于惰性体基准 (IBR2%)。结果与高温生物炭的高碳稳定性一致。相比之下，碳化不充分且主要由半惰性生物炭组成的生物炭样品含有痕量烷烃、挥发性化合物以及分子结构中带有芳香键的较高程度的烷基化。这表明更容易氧化和微生物分解，因此碳结构的凝聚度和稳定性较差。此外，惰性生物炭中这些化合物的出现表明生物炭碳结构内保留有游离烃。 Py-GC/MS 数据补充了微观和大量地球化学数据，另外还有利于评估生物炭样品的稳定性条件。