Aerodynamic Properties of Biochar Particles: Effect of Grinding and Implications

Abstract

This study reports the aerodynamic properties of ground biochar particles produced from the slow pyrolysis of mallee biomass at 400 °C, considering grinding times from 10 s to 16 min. The data show that extensive grinding (e.g., ≥ 1 min) substantially increases the amounts of particulate matter with an aerodynamic diameter of <10 µm (PM10) and <2.5 µm (PM2.5) in the ground biochars. Whereas the aerodynamic particle size distribution (PSD) of PM10 in biochar after grinding for 10 s shows no obvious peak, a bimodal PSD is observed for PM10 in the biochars after grinding for 1-16 min. The results suggest that care must be taken during biochar grinding to minimize the PM10 and PM2.5 produced. PM10 and PM2.5 in a biochar should also be quantified to assess environmental risks during biochar transport and applications.