Insight into biomass feedstock on formation of biochar-bound environmentally persistent free radicals under different pyrolysis temperatures
Yu Wang, Xinfeng Gu, Yue Huang, Zhuhong Ding, Yijun Chen, Xin Hu
Abstract
factors ranged from 2.0025 to 2.0042 and line width was in the range of 2.15-11.3 for EPFRs in the resulting biochars. Spin concentrations of biochar-bound EPFRs increased with the increasing pyrolysis temperatures from 200 to 500 °C, and then decreased rapidly from 500 to 700 °C and oxygen-centered radicals shifted to carbon-centered radicals with the increasing pyrolysis temperatures from 200 to 700 °C for all the studied biomass feedstock. 300-500 °C was the appropriate pyrolysis temperature range for higher levels of spin concentrations of biochar-bound EPFRs. Moreover, EPFRs' concentrations had significantly positive correlation with C contents and weak or none correlation with contents of transition metals. Overall, different types of biomass feedstock have significant impact on the formation of EPFRs in the resulting biochars.