Li Simeng, Chen Gang
Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310, USA.
Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310, USA.
Waste Manag. 2018 Aug;78:198-207. doi: 10.1016/j.wasman.2018.05.048. Epub 2018 Jun 7.
Biochar is a promising biomass product for soil amendment, remediation, and carbon sequestration. In this study, the effect of pyrolysis temperature and feedstock type on biochar physiochemical properties including stability, recalcitrance, and surface functionality were investigated through thermogravimetric, thermochemical, and infrared spectral analyses. It is concluded in this research that pyrolysis temperature was the dominating factor determining the inherent characteristics of the derived biochar. High-temperature pyrolysis (≥600 °C) derived the biochar with a high pH, stability, recalcitrance, and higher heating value (HHV). On the other hand, the biochar produced from low-temperature pyrolysis (≤400 °C) had a larger mass yield, energy recovery, more volatile content, and diverse surface functional groups. The different biochar characteristics will lead to different agricultural and environmental applications. Also in this research, a carbon-based recalcitrance index (R) based on a novel multi-element scanning thermal analysis (MESTA) was proposed to improve the current recalcitrance index (R) based on the conventional thermogravimetric analysis (TGA) for the evaluation of biochar's carbon sequestration potential. The direct comparison of the two indexes, as well as the results from the infrared spectral analysis and ultimate analysis, indicated that R was better at characterizing biochar's recalcitrance, especially when the mineral content of the feedstock was high. In addition, the cost breakdown indicated that the pretreatment of feedstock was the costliest process during biochar production.
生物炭是一种很有前景的生物质产品，可用于土壤改良、修复和碳固存。在本研究中，通过热重分析、热化学分析和红外光谱分析，研究了热解温度和原料类型对生物炭物理化学性质（包括稳定性、难降解性和表面官能团）的影响。本研究得出结论，热解温度是决定衍生生物炭固有特性的主要因素。高温热解（≥600 °C）得到的生物炭具有高pH值、稳定性、难降解性和较高的热值（HHV）。另一方面，低温热解（≤400 °C）产生的生物炭具有更高的质量产率、能量回收率、更多的挥发性成分和多样的表面官能团。不同的生物炭特性将导致不同的农业和环境应用。同样在本研究中，基于新型多元素扫描热分析（MESTA）提出了一种基于碳的难降解指数（R），以改进基于传统热重分析（TGA）的当前难降解指数（R），用于评估生物炭的碳固存潜力。两种指数的直接比较以及红外光谱分析和元素分析的结果表明，R在表征生物炭的难降解性方面表现更好，尤其是当原料的矿物质含量较高时。此外，成本分析表明，原料预处理是生物炭生产过程中成本最高的环节。
