Pyrolysis Atmospheres and Temperatures Co-Mediated Spectral Variations of Biochar-Derived Dissolved Organic Carbon: Quantitative Prediction and Self-Organizing Maps Analysis

• Published in: Molecules (Basel, Switzerland) Vol. 28; no. 5; p. 2247
• Main Authors: Zhang, Huiying, Ni, Jinzhi, Qian, Wei, Yu, Shuhan, Xiang, Yu, Yang, Liuming, Chen, Weifeng
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 28.02.2023; MDPI
• Subjects: Activated carbon; Atmosphere; Atmospheres; Atmospheric chemistry; biochar-derived dissolved organic carbon; Carbon; Carbon dioxide; Carbon Dioxide - analysis; Charcoal; Chemical properties; Chemical research; Climate change; Dissolved organic carbon; Dissolved Organic Matter; Environmental effects; Fluorescence; Humic Substances - analysis; Humification; Molecular weight; Polarity; Pollutants; Pyrolysis; pyrolysis atmospheres; Quantitative analysis; Self organizing maps; spectral characteristics; Temperature; Thermal properties; China; biochar-derived dissolved organic carbon; pyrolysis atmospheres; quantitative analysis; self-organizing maps; spectral characteristics
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules28052247

Biochar-derived dissolved organic carbon (BDOC), as a highly activated carbonaceous fraction of biochar, significantly affects the environmental effect of biochar. This study systematically investigated the differences in the properties of BDOC produced at 300-750 °C in three atmosphere types (including N and CO flows and air limitation) as well as their quantitative relationship with biochar properties. The results showed that BDOC in biochar pyrolyzed in air limitation (0.19-2.88 mg/g) was more than that pyrolyzed in N (0.06-1.63 mg/g) and CO flows (0.07-1.74 mg/g) at 450-750 °C. The aliphaticity, humification, molecular weight, and polarity of BDOC strongly depended on the atmosphere types as well as the pyrolysis temperatures. BDOC produced in air limitation contained more humic-like substances (0.65-0.89) and less fulvic-like substances (0.11-0.35) than that produced in N and CO flows. The multiple linear regression of the exponential form of biochar properties (H and O contents, H/C and (O+N)/C) could be used to quantitatively predict the bulk content and organic component contents of BDOC. Additionally, self-organizing maps could effectively visualize the categories of fluorescence intensity and components of BDOC from different pyrolysis atmospheres and temperatures. This study highlights that pyrolysis atmosphere types are a crucial factor controlling the BDOC properties, and some characteristics of BDOC can be quantitatively evaluated based on the properties of biochar.