Jiangxi Provincial Key Laboratory of Genesis and Remediation of Groundwater Pollution, East China University of Technology, Nanchang, 330013, China.
School of Water Resources and Environmental Engineering, East China University of Technology, Nanchang, 330013, China.
Sci Rep. 2024 Nov 25;14(1):29192. doi: 10.1038/s41598-024-79032-8.
Biomass pyrolysis greatly impacts climates, ecosystem dynamics, air quality, human health, global carbon and nitrogen cycle. The emissions of nitrogen-containing compounds from biomass pyrolysis highly depend on the protein nitrogen existing in biomass. However, the quantitative kinetic information, including the rate constant and apparent activation energy of individual amino acid induced by pyrolysis are still yet to be well-constrained. Towards this, we performed a series of controlled pyrolysis experiments where 18 equimolar free amino acids standard mixtures were pyrolyzed under ambient oxygen at temperatures between 160 and 240 °C. Additionally, straw samples were pyrolyzed to understand the mechanism of combined amino acids in protein liberation to free amino acids during pyrolytic processes. Our observations indicated that an increase in heating duration and temperature promote the degradation of free amino acids. Further, the heating stability of the 18 examined amino acids varied, which could be related to the length and functional groups present in their side chains. Our result shows that the degradation processes of all examined 18 amino acids followed irreversible first-order reaction kinetics in air within the given temperature range, with their activation energy ranging from 88.5 to 137.44 kJ mol. The distinct distribution patterns of both combined and free amino acids in aerosol samples from straw pyrolytic processes were obtained. The kinetic information of amino acids garnered herein helps to elucidate the transformation mechanisms of nitrogenous compounds during biomass burning.
生物质热解对气候、生态系统动态、空气质量、人类健康以及全球碳氮循环都有重大影响。生物质热解过程中含氮化合物的排放高度依赖于生物质中存在的蛋白质氮。然而，目前对于热解过程中个别氨基酸的定量动力学信息，包括速率常数和表观活化能，仍然缺乏很好的约束。为此，我们进行了一系列控制热解实验，将 18 种等摩尔的游离氨基酸标准混合物在环境氧气中于 160-240°C 之间的温度下进行热解。此外，我们还对秸秆样品进行了热解，以了解在热解过程中蛋白质中结合氨基酸向游离氨基酸释放的机制。我们的观察结果表明，加热时间和温度的增加会促进游离氨基酸的降解。此外，18 种被检测氨基酸的加热稳定性不同，这可能与其侧链的长度和官能团有关。我们的结果表明，在所研究的温度范围内，所有 18 种氨基酸的降解过程均遵循空气环境中的不可逆一级反应动力学，其活化能范围为 88.5-137.44kJ/mol。我们还获得了秸秆热解过程中气溶胶样品中结合态和游离态氨基酸的不同分布模式。本文获得的氨基酸动力学信息有助于阐明生物质燃烧过程中含氮化合物的转化机制。
