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Thermal stability and oxidation resistance of biochars derived from corn stalk and wheat stalk
Received:September 13, 2018  Revised:November 19, 2018
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KeyWord:biochar;crop straw;thermal stability;oxidation resistance
Author NameAffiliationE-mail
ZHAO Jin-feng Faculty of Environmental Science and Engineering, Kunming University of Science & Technology, Kunming 650500, China  
CHEN Jing-wen Faculty of Environmental Science and Engineering, Kunming University of Science & Technology, Kunming 650500, China  
ZHANG Di Faculty of Environmental Science and Engineering, Kunming University of Science & Technology, Kunming 650500, China
Yunnan Key Laboratory of Carbon Sequestration and Pollution Controlling, Kunming 650500, China 
zhangdi2002113@sina.com 
Ghosh Saikat Faculty of Environmental Science and Engineering, Kunming University of Science & Technology, Kunming 650500, China  
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Abstract:
      The objective of this study is to explore the chemical properties and thermal stability of biochars prepared from corn and wheat stalks, which are agricultural wastes. The biochars were prepared at 200℃ and 500℃. Physical and chemical properties and thermal stability of the biochars were investigated by elemental analysis, fourier transformed infrared spectroscopy (FTIR), and thermo-gravimetric (TGA-DTA)analysis. The results showed that the relative heat stability of corn stalk biochar was higher than that of wheat stalk biochar prepared at the same temperature, which was attributed to the higher lignin content of the former. In addition, biochars prepared from the same raw materials at a higher temperature showed better thermal stability due to rise in aromaticity. Oxidation of the biochars by NaClO, H2O2, and KMnO4 was minimal. In addition to a high lignin content, mineral protection in stalk biochars prevented oxidation. Particularly, in the KMnO4 system, the wheat stalk biochar, despite lower lignin content, showed stronger chemical stability due to the high ash content, hence, showing a different mode of thermal stability. Besides, the biochars prepared at higher temperatures exhibited a rise in the antioxidant capacity and carbon sequestration potential. This study provides valuable insights regarding the practical application and stability of straw biochars.