Sustainable Utilization of King Coconut Husk as a Feedstock in Biochar Production with the Highest Conversion Efficiency and Desirable Properties

Abstract

Abstract King coconut husk biochar is a soil amendment that can potentially increase soil fertility in degraded soils under perennial coconut plantations. This experiment was conducted in a laboratory to investigate the properties of biochar produced with different cut sizes of king coconut husk under different pyrolysis conditions. Full husk, 1/2nd cuts, 1/4th cuts, 1/8th cuts, and chips of king coconut husk were pyrolyzed at 300°C and 500°C temperatures for 20, 30, 40, 60, 90, and 180 minutes of residence times, respectively. Even though partial pyrolysis was observed at 300°C under a few residence times, complete pyrolysis was observed at 500°C under all six residence times. Increasing the residence time caused a statistically significant (P<0.05) reduction in biochar yield at 500°C due to the removal of chemical compounds and gases by thermal decomposition under prolonged high-temperature conditions, resulting in low biochar output. The fixed carbon, volatile matter, ash, and pH levels have not improved substantially due to prolonged residence time. The highest level of fixed carbon was detected after 60 minutes of residence time with the least amount of ash and volatile components. Using biochar made from king coconut husk with a 1/4th cut size as a soil amendment with minimal processing and drying activity will be economically viable to increase carbon sequestration.