Abstract Important parameters that influence biochar properties include charring temperature and biomass type. We characterized the molecular properties of biochars from five agricultural residues with pyrolysis gas chromatography mass/spectrometry (pyrolysis-GC/MS) in comparison with atomic H/C and N/C ratios. Feedstocks included chicken manure, eucalyptus sawdust, coffee husk, sugarcane bagasse and pine bark. Biochars produced at three different temperatures (T char ) were analyzed, including 350, 450 and 750 °C, as well as the uncharred materials. The optimum temperature during analysis with pyrolysis-GC/MS (T py ) was examined. T py 600 °C gave the best results for all T char by showing a larger diversity of pyrolysis products compared to T py 700 °C and 800 °C; T py 600 °C was therefore used for qualitative and quantitative comparison of the samples. Charring temperature was the dominant factor that determined the chemical composition of the biochar pyrolysates. Uncharred feedstocks had the largest contribution from carbohydrates, lignin phenols and long chain n -alkanes, all of which rapidly decreased with charring; biochars produced at T char 350 and 450 °C showed the largest contribution from phenols, mid-chain n -alkanes, benzofurans, indenes, biphenyls and PAHs, from which the benzofurans, indenes, biphenyls and PAHs were particular abundant in samples produced at T char 450 °C; pyrolysates of biochars produced at T char 750 °C were characterized by branched aliphatics, short chain n -alkanes/ n -alkenes and low molecular weight (LMW) benzenes. Factor analysis showed that the variation of products differed largely within some chemical groups. For the N-containing compounds, caffeine, C 16 alkylnitrile and diketopiperazines were associated with uncharred materials, benzonitriles and quinolines were associated with T char 350–450 °C. Another part of the variation of N-containing compounds was associated with chicken manure, and to a lesser extend also coffee husk, independently of T char . For all five agricultural residues, the highest chemical diversity was found for biochar produced at T char 350 °C. As the charring temperature increased, the diversity of pyrolysis products diminished.

中文翻译：

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在不同炭化温度下获得的五种巴西农业残留物的生物炭的分子表征

摘要 影响生物炭特性的重要参数包括炭化温度和生物质类型。与原子 H/C 和 N/C 比率相比，我们使用热解气相色谱质谱/质谱（热解-GC/MS）表征了来自五种农业残留物的生物炭的分子特性。原料包括鸡粪、桉树锯末、咖啡壳、甘蔗渣和松树皮。分析了在三种不同温度 (T char ) 下生产的生物炭，包括 350、450 和 750 °C，以及未烧焦的材料。检查了热解-GC/MS (T py ) 分析过程中的最佳温度。与 T py 700 °C 和 800 °C 相比，T py 600 °C 显示出更大的热解产物多样性，从而为所有 T char 提供了最佳结果；因此，T py 600 °C 用于样品的定性和定量比较。炭化温度是决定生物炭热解产物化学成分的主要因素。未烧焦的原料中碳水化合物、木质素酚和长链正构烷烃的贡献最大，所有这些都随着炭化而迅速减少；在 T char 350 和 450 °C 下生产的生物炭显示苯酚、中链正构烷烃、苯并呋喃、茚、联苯和 PAH 的贡献最大，其中苯并呋喃、茚、联苯和 PAH 在 T 生产的样品中特别丰富炭450℃；在 T char 750 °C 下生产的生物炭热解产物的特征是支链脂肪族、短链正构烷烃/正构烯烃和低分子量 (LMW) 苯。因子分析表明，产品的变异在某些化学组内差异很大。对于含氮化合物，咖啡因、C 16 烷基腈和二酮哌嗪与未烧焦的材料相关，苯甲腈和喹啉与 T char 350–450 °C 相关。含氮化合物的另一部分变异与鸡粪有关，在较小程度上也与咖啡壳有关，与 T char 无关。对于所有五种农业残留物，在 T char 350 °C 下生产的生物炭的化学多样性最高。随着炭化温度的升高，热解产物的多样性减少。苯甲腈和喹啉与 T char 350–450 °C 相关。含氮化合物的另一部分变异与鸡粪有关，在较小程度上也与咖啡壳有关，与 T char 无关。对于所有五种农业残留物，在 T char 350 °C 下生产的生物炭的化学多样性最高。随着炭化温度的升高，热解产物的多样性减少。苯甲腈和喹啉与 T char 350–450 °C 相关。含氮化合物的另一部分变异与鸡粪有关，在较小程度上也与咖啡壳有关，与 T char 无关。对于所有五种农业残留物，在 T char 350 °C 下生产的生物炭的化学多样性最高。随着炭化温度的升高，热解产物的多样性减少。