Biochar and bio-oil fuel properties from nickel nanoparticles assisted pyrolysis of cassava peel

Direct biomass usage as a renewable fuel source and substitute for fossil fuels is discouraging due to high moisture, low energy density and low bulk density. Herein, thermogravimetric analysis (TGA) was conducted at various heating rates to determine peak decomposition temperatures for the dried cassava peels (DCP). The influence of pyrolysis temperature (300, 400, 500 and 600 degrees C) and heating rates (10, 20 and 30 degrees C/min) on the nickel nanoparticles catalyzed decomposition of DCP to produce biochar, bio-oil and biogas was investigated and characterized. The results revealed higher biochar (CBC) yield of 68.59 wt%, 62.55 wt% and 56.92 wt% at lower pyrolysis temperature of 300 degrees C for the different heating rates of 10, 20 and 30 degrees C/min. The higher carbon content of 52.39, 53.30 and 55.44 wt% was obtained at elevated temperature of 600 degrees C and heating rates of 10, 20 and 30 degrees C/min, respectively. At the pyrolysis temperature of 600 degrees C and heating rates of 10, 20 and 30 degrees C/min, the optimum yield of bio-oil (24.35, 17.69 and 18.16 wt%) and biogas (31.35, 42.03 and 46.12 wt%) were attained. A high heating value (HHV) of 28.70 MJ/kg was obtained for the biochar at 600 degrees C. Through the TGA, FTIR and HRSEM results, the thermal stability, hydrophobicity and structural changes of DCP and CBC samples were established. Similarly, the thermal stability of CBC samples increased with increasing pyrolysis temperature. Biochar with optimum fuel properties was produced at 600 degrees C due to the highest carbon content and high heating value (HHV). Improved kinematic viscosity (3.87 mm(2)/s) and density (0.850 g/cm(3)) were reported at the temperature of 300 degrees C and heating rate of 30 degrees C/min, while a higher pH (4.96), HHV (42.68 MJ/kg) and flash point (53.85 min) were presented by the bio-oil at the temperature of 600 degrees C and heating rate of 30 degrees C/min. Hence, DCP produced value-added biochar and bio-oil as renewable energy.