PYROLYSIS TEMPERATAURE EFFECTS ON PROPERTIES OF BIOCHAR DERIVED FROM ORGANIC SEED CAKES

Abstract

Biochar is a carbon-rich material created when biomass is pyrolyzed. Biochar made from organic seed cakes can be used by small-scale farmers as soil amendments, which also reduces the waste deposited at local extraction sites thereby reducing environmental pollution. The temperature at which biochar is pyrolyzed significantly impacts its properties and effectiveness. In this study, biochar was produced from various organic seed cakes (waste/residues produced after extraction of oil from seeds) using a furnace at three different pyrolysis temperatures (500˚C, 600˚C and 700˚C) for an hour. Type of organic seed cakes used for biochar production were neem seed cake (NSC), palm kernel cake (PKC) and shea seed cake (SSC). The produced biochars were analyzed for pH, electrical conductivity (EC), total nitrogen, total phosphorus and organic carbon. Other properties like calcium, magnesium, zinc, iron and potassium were also determined. The pH, EC, OC, C/N ratio, P, K, Ca, Mg, Zn and Fe increased with increasing pyrolysis temperature for all seed cakes. The rise in pH could be as a result of the breakdown of acidic functional groups such as carboxyl groups at elevated temperature. However, total N decreased as pyrolysis temperature increased. The decrease in N reveals that this element exists as nitrogen dioxide and may have become volatile after pyrolysis. Organic carbon, N and Zn of NSC and PKC biochar recorded lower C/N ratios and higher Zn contents compared to the SSC. The results show that biochar produced at 500C pyrolysis temperature could a more effective soil amendment due to its lower C/N ratio. The results also indicate that NSC and PKC are better soil amendment compared to SSC.