Comprehensive Characterization of Biochars Produced from Three Major Crop Straws of China

Biochars produced from rice straw, corn straw, and wheat straw under different pyrolysis temperatures were comprehensively characterized. The results indicated that the yields of the biochars decreased for all three biochar types with the increase in pyrolysis temperature from 250 °C to 600 °C. In addition, the carbon contents of the biochars increased, and the polar acidic functional groups decreased with the increase of the pyrolysis temperature. The hemicellulose and cellulose components likely decomposed at approximately 300 °C, and more condensed and ordered aromatic carbon structures were formed in the biochars with the increase in pyrolysis temperature. The results also indicated that these three types of biochars showed many similarities in elemental composition and structure. However, some differences were also observed. This work provides important baseline information for the production of biochars from crop residues with desired properties for environmental applications.