Biochar production, yield and quality characterization from different feedstocks and kilns

Pyrolysis conditions and feedstock have been highlighted as key indicators for biochar (BC) utility in various fields. Consequently, this study investigated the effect of feedstock type [corn cob (CC), coconut husk (CCH), and empty fruit bunch (EFB)] and kiln type (Elsa barrel and a top-lit updraft (TLUD) kiln) on BC pyrolysis conditions, yield, and characterisation produced under slow pyrolysis. Key parameters such as pH, electrical conductivity (EC), total nitrogen (TN), organic carbon (OC), and fixed carbon (FC) were determined. SEM-EDX, XRD, and FTIR were used to characterise BC quality. Results showed a respective 4 % and 30 % increment in pyrolysis temperature of CC-BC compared to EFB-BC when Elsa barrel and TLUD kilns were employed. Consequently, BC yield was, respectively, 71 % and 49 % higher for EFB on Elsa barrel and the TLUD kiln when compared with CC. Utilising the Elsa barrel, EFB-BC recorded an 11 % higher burn rate than with CC-BC feedstock, whereas a 70 % higher burn rate was observed for EFB-BC relative to CC-BC when the pyrolysis was done with the TLUD kiln. A similar trend was observed for the residence time. CC-BC in the Elsa barrel recorded 1.7 % higher pH, 4.8 % increase in EC, 16.8 % increase in TN, and 4.2 % higher FC compared to CC-BC in the TLUD kiln. SEM analysis indicated that BC from the Elsa barrel had more uniform and porous structures. The findings provide valuable insights into optimising BC production processes for sustainable agricultural and environmental applications.