Effect of pyrolysis temperature on the physiochemical properties of biochars produced from raw and fermented rice husks

This study investigated the slow pyrolysis behavior of raw rice husk (RRH) and fermented rice husk (FRH) in a fixed-bed reactor at temperatures in the range of 200–600 °C. The effects of pyrolysis temperature on the biochar yield, composition, and physiochemical properties were examined to evaluate the energy potential of biochars produced from RRH and FRH. The FRH-derived biochar produced at 600 °C was found to be more suitable than the RRH-derived biochar because of its higher carbon content (68.9% vs 42.1%), GCV (31.6 vs 24.1 MJ kg −1 ), and true density (1.94 vs 1.54 g cm −3 ). The slow pyrolysis in the high-temperature regime facilitated the formation of lignin-rich and aromatically condensed biochar, making it particularly useful for producing carbon-rich materials. Thus, slow pyrolysis can be a technically viable approach for producing high-energy-density solid fuels that can replace medium-ranking coals in co-firing.