Low temperature production of biochars from different biomasses: Effect of static and rotary lab reactors and application as soil conditioners

Abstract

Abundant renewable resources, such as biomass, can acquire added value when applied in industrial processes, such as slow pyrolysis to produce biochar. The type of biomass and the pyrolysis conditions are factors that determine the characteristics of the resulting biochars, influencing their potential applications. In this work, biochars were produced at 350 °C from sugarcane bagasse (SB), exhausted black wattle bark (EH), and elephant grass (EG). The materials were characterized considering the effects of different pyrolysis methods: (1) tube (laboratory scale), (2) rotary, and (3) muffle furnace (industrial scale). Despite using the same temperature, the formation of structures with condensed aromatic rings, the order of the processes that tended to form this type of structure was (3) ≥ (2) > (1). Pyrolysis method (3) tended to carbonize the constituents of biomass, than the other processes, which was promising for the production of biochar on an industrial scale. Besides, an investigation was made of the effects of applying BEG3 and BEH3 biochars as soil conditioners to mitigate emissions of N2O (a major greenhouse gas) and improve productivity in the cultivation of black oats. The BEG3 reduced the release of N2O from the soil, mainly affecting its peak emission, in addition to increasing the productivity of black oats by a factor of 1.22, compared to the control, being statistically significant results. It could be concluded that elephant grass biochar produced on an industrial scale is suitable for application to soils.