Characterization of bio-oil and bio-char obtained from black cumin seed by hydrothermal liquefaction: investigation of potential as an energy source

In this study, black cumin seed cake was converted to liquid and solid products with catalyst (Al2O3, Ca(OH)2, SnCl4.5H2O) and without catalyst at 300°C, 325°C, and 350°C by using the hydrothermal liquefaction method. The obtained products were analyzed by GC-MS, FT-IR, SEM, elemental analysis, and the 1H NMR method. The highest light bio-oil yield was determined as 3.18% at 350°C with the catalyst SnCl4.5H2O and the highest heavy bio-oil yield was found to be 37.37% at 300°C with the catalyst Al2O3. According to the results of the elemental analysis, the energy values of the liquid products (Light, Heavy bio-oil) varied between 21.87 and 31.78 Mjkg−1 and the energy values of the solid products ranged between 16.22 and 18.28 Mjkg−1. In the GC-MS analysis of the liquid products gained at 300°C and 350°C, a large number of different compounds, generally composed of monoaromatic, aliphatic, polyaromatic, and oxygenated compounds, were obtained.