| Title: | Pyrolysis characteristics of soil humic substances using TG-FTIR-MS combined with kinetic models |
| Author(s): | Li T; Song F; Zhang J; Liu S; Xing B; Bai Y; |
| Address: | "State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 10012, China. State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 10012, China; College of Water Sciences, Beijing Normal University, Beijing 100875, China. State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 10012, China; School of Environmental and Safety Engineering, Changzhou University, Jiangsu 213164, China. Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA. State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 10012, China. Electronic address: baiyc@craes.org.cn" |
| DOI: | 10.1016/j.scitotenv.2019.134237 |
| ISSN/ISBN: | 1879-1026 (Electronic) 0048-9697 (Linking) |
| Abstract: | "The incorporation and cycling of pyrogenic organic matter in soil is a potential carbon sink, while the pyrolysis behaviors of soil organic matter are still lacking. Pyrolysis characteristics of soil fulvic acid (FA) and humic acid (HA) were investigated using thermogravimetry combined with Fourier transform infrared spectrometer-mass spectrometer (TG-FTIR-MS) and kinetic models. Four reaction stages corresponding to four pseudo-components were distinguished for both FA and HA. FA exhibited greater transformation contributions of hemicellulose-like and cellulose-like pseudo-components, while HA exhibited greater transformation contributions of lignin-like pseudo-components. Compared to HA, higher levels of heat-resistant aromatic compounds, phenolic groups, and carboxylic groups were recognized in FA. Values of both activation energy (Ea, 246.13-661.40?ª+kJ.mol(-1)) and pre-exponential factor (lnA, 53.49-107.16?ª+min(-1)) of FA were greater than corresponding Ea (241.74-466.70?ª+kJ.mol(-1)) and lnA (51.99-74.36?ª+min(-1)) values of HA determined by Flynn-Wall-Ozawa method and Distributed Activation Energy Model. The main pyrolysis reaction mechanisms of both FA and HA closely matched with the order-based model corresponding to 2nd and 3rd order random nucleation on an individual particle. The evolved gas species of H(2), CH(4), H(2)O, and CO(2) were dominant for FA and HA pyrolysis. Generally, the total H(2)/CO(2) and CH(4)/H(2)O releases were relatively larger for FA and HA pyrolysis, respectively. TG-FTIR-MS is shown to be an effective method to provide valuable and qualitative analysis of the gaseous volatile species evolved during HS pyrolysis. Findings from this systematic study of soil organic matter responding to pyrolysis will be critical for predicting the changes of soil systems or carbon cycle affected by future climate and fire regimes" |
| Keywords: | Heat-resistance Humic substances Thermal degradation Volatile species; |
| Notes: | "PubMed-not-MEDLINELi, Tingting Song, Fanhao Zhang, Jin Liu, Shasha Xing, Baoshan Bai, Yingchen eng Netherlands 2019/09/09 Sci Total Environ. 2020 Jan 1; 698:134237. doi: 10.1016/j.scitotenv.2019.134237. Epub 2019 Sep 2" |
