https://doi.org/10.1016/j.ccst.2021.100018
“Compared to the N-containing functionalities, biomass derivatives as precursors are more sustainable and available (Zhao et al., 2010). Some biomass samples that have a high content of nitrogen have been concluded in Table 1 (Leng et al., 2020). Microalgae occupies the highest N-content with 13.94%, and its turning biochar is 6.57%–12.93%. Chitosan also performs well with the 9.4% N-content in biomass and 8.9-9.1% N-content in produced biochar. In addition, the porous carbon derived from Zein reaches up to 14.92%. Most nitrogenous groups in the biomass exit in the form of both inorganic N-functional groups (e.g. NH4–N, NO2–N, and NO3–N) (Liu et al., 2018) and organic N-functional groups (e.g. pyridinic-N, pyrrolic-N, quaternary-N, pyridinic-N-oxide, graphitic-N, amine-N, amide-N, nitrile-N, etc.) (Yuan et al., 2018). After pyrolysis, nitrogen-rich components may convert into pyridinic-N, pyrrolic-N, quaternary-N, and possibly pyridinic-N-oxide (Chen et al., 2017). Generally, the higher nitrogen content leads to the higher nitrogen content of porous carbon. However, the pyrolysis may also lead to the loss of nitrogen in the biomass as the nitrogen-containing groups may convert into nitrogen-containing gases (e.g. NH3). Among the nitrogen-containing biomass including cotton stalk, walnut shell, rice husk and london plane leaves have been used to produce biochar as CO2 adsorbents. However, these biomass are not outstanding nitrogen content of biomass, more possibilities can be further explored.”
