Effect of pyrolysis temperature on composition, carbon fraction and abiotic stability of straw biochars: correlation and quantitative analysis

Abstract

Biochar provides an important pathway for the global response to climate change. The abiotic stability of biochar is important for its application in carbon capture and sequestration. To systematically illustrate the effects of pyrolysis temperature on composition, carbon fraction and abiotic stability of straw biochar, four kinds of straw biochars were prepared at pyrolysis temperatures of 300 °C, 400 °C, 500 °C, and 600 °C, respectively. The ultimate and proximate compositions, different carbon fractions and abiotic stability of prepared biochar were characterized, and their qualitative and quantitative relationships were established by Kendall correlation analysis, factor analysis and different regression analysis methods. Results showed that pyrolysis temperature influenced compositions and carbon fractions directly, which affected the abiotic stability of biochar (p < 0.01). The higher the pyrolysis temperature (up to 500 °C), the higher the abiotic stability of biochar. The different abiotic stability indicators, including thermal stability (ratios of volatile matter and fixed carbon, hydrogen and organic carbon, oxygen and organic carbon, and thermal stability index R50), dissolution stability and chemical oxidation-resistant stability of biochar, all followed exponential functions with pyrolysis temperature. Unitary and binary linear regression equations among compositions, carbon fractions and the abiotic stability evaluation indicators were established. We hope that the results are scientifically valuable for a better understanding of the inherent properties of straw biochar, and thus help simplify the screening of appropriate indicators for evaluating the properties and abiotic stability of biochar.Graphical