Investigating the relative solubilities of three coal ranks in an organic solvent

Our study investigates the solubility of three coal ranks in an n-octane solvent. The types examined were lignite, bituminous, and anthracite. The solubilities of the three ground coal rank samples were determined using the ultraviolet-visible spectroscopy technique. This technique exposed the coal solution to ultraviolet light, enabling the evaluation of peak energy absorbance. The approach taken in this study involved the preparation of coal samples, followed by size reduction and solubility assessments conducted in line with the design of experiment (DOE) methodology. Ultimately, the outcomes for peak absorbance and the corresponding wavelength were acquired through statistical analysis and graphical interpolation methods. The findings indicated a direct proportional correlation between coal grindability and the inherent strength, hardness, or toughness of the coal to fracture. Results indicated that lignite coal demonstrated the highest total reflectance absorbance (4.20 × 10 a.u.) at a wavelength of 355.951 nm, while bituminous coal followed with an absorbance of 2.50 × 10 a.u. at a wavelength of 207.5119 nm, and anthracite showed the lowest absorbance of 1.70 × 10 a.u. at a wavelength of 207.5119 nm. The spectrum findings indicated that the relative solubility levels of lignite, bituminous, and anthracite coals were notably distinct.