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.