Physicochemical characteristics of biochars can be beneficially manipulated using post-pyrolyzed particle size modification

This work aimed to study the changes in the physicochemical properties of biochars induced by post-pyrolyzed particle size processing. Twelve distinct physicochemical attributes of four different particle sized biochars, derived from three different feedstocks, including rice husk, tea wastes and woodchips; were investigated. Amongst all of the investigated characteristics water repellency (eta(2)=0.99) and mean pore diameter (eta(2)=0.95) were the characteristics most affected by feedstock type and particle size, respectively. The interaction effect between biochar type and particle size was extremely significant (P < 0.001) for surface area and mean pore diameter. While feedstock mainly controlled biochar characteristics, most characteristics were also particle size dependent, where size dependency was more influential on physical than chemical properties. For most properties a significant interaction effect between biochar type and particle size was also detected.