Effects and mechanism of pyrolysis temperature on physicochemical properties of corn stalk pellet biochar based on combined characterization approach of microcomputed tomography and chemical analysis

To further explain effects of pyrolysis temperature on physicochemical properties of corn stalk pellet biochar from a new perspective, various lab physicochemical analysis methods combining microcomputed tomography were used to characterize biochar in this study. The results showed that at pyrolysis temperatures from 300 degrees C to 800 degrees C, yield of biochar decreased logarithmically with increasing pyrolysis temperature (T); changes of proximate and elemental compositions all showed significant differences, but the change rules were not consistent; high temperature pyrolysis biochar had high stability, high hardness and was convenient for storage and transportation; the proportions of hydroxyl group and amino group were highest in BC800 and BC600, respectively, contributing to the adsorption and removal of pollutants; BC400 had the best combustion performance; X-ray mean attenuation coefficient (XMAC) showed the following correlations, namely, XMAC = 0.003*ln(T-285.329) + 0.011 (R-2 = 0.904) and XMAC = -0.031*(VM/100) + 0.021*(Ash/100) + 0.027 (R-2 = 0.915). Above results provide important basic data support for development of corn stalk pellet biochar.

Automated summary

Through various lab physicochemical analysis methods and microCT, it was found that high temperature pyrolysis biochar exhibited high stability and hardness, making it suitable for storage and transportation; BC800 and BC600 had the highest proportions of hydroxyl and amino groups, contributing to pollutant adsorption and removal; BC400 showed the best combustion performance.