Nanjing Institute of Environmental Science, Ministry of Ecology and Environment of the People's Republic of China, Nanjing, 210042, PR China.
Nanjing Institute of Environmental Science, Ministry of Ecology and Environment of the People's Republic of China, Nanjing, 210042, PR China; Co-Innovation Center for the Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, PR China; College of Environment, Hohai University, Nanjing, 210098, PR China.
Chemosphere. 2023 Apr;321:138138. doi: 10.1016/j.chemosphere.2023.138138. Epub 2023 Feb 13.
Much research has been done on the preparation and application of hydrochars, but research on the release characteristics of hydrochar-derived dissolved organic matter (HDOM) is very limited; clarifying the release characteristics of HDOM is important for understanding and adjusting the environmental behaviour of hydrochar. Herein, the potential release of HDOM from rice straw-derived hydrochars prepared at different hydrothermal temperatures was investigated under various potential environmental conditions for the first time. The total release quantity and humification degree of HDOM decreased with increasing hydrothermal temperature. The critical dividing line for various hydrothermal reactions, decomposition and polymerization, was in the range of 240 °C-260 °C. Alkaline condition increased the HDOM release amount (up to 299 mg g), molecular weight (as high as 423 Da) and molecular diversity (8857 compounds) from rice straw-derived hydrochars. The unique substances of HDOM released under alkaline condition were mainly distributed in lipids-like substances, CRAM/lignins-like substances, aromatic structures, and tannins-like substances, while few unique substances were found under acidic condition. Additionally, CRAM/lignins-like substances were the most abundant in all HDOM samples, reaching 82%, which were relatively stable and could achieve carbon sequestration in different environments. The findings provided a new insight on understanding the potential environment behaviors of hydrochar.
已经有很多关于水热炭的制备和应用的研究，但对于水热炭衍生溶解有机物（HDOM）的释放特性的研究却非常有限；阐明 HDOM 的释放特性对于理解和调节水热炭的环境行为非常重要。在此，首次研究了不同水热温度下制备的水稻秸秆水热炭在各种潜在环境条件下 HDOM 的潜在释放情况。HDOM 的总释放量和腐殖化程度随水热温度的升高而降低。各种水热反应、分解和聚合的临界分界线在 240°C-260°C 范围内。碱性条件增加了水稻秸秆水热炭中 HDOM 的释放量（高达 299mg/g）、分子量（高达 423Da）和分子多样性（8857 种化合物）。碱性条件下释放的 HDOM 的特有物质主要分布在类脂物质、CRAM/木质素类物质、芳香结构和鞣质类物质中，而在酸性条件下几乎没有发现特有物质。此外，在所有 HDOM 样品中，CRAM/木质素类物质含量最高，达到 82%，它们相对稳定，可以在不同环境中实现碳封存。这些发现为理解水热炭的潜在环境行为提供了新的见解。
