• [EMIM][FeCl4] ionic liquid exhibits high selectivity for separating tetralin from dodecane and decalin, with selectivity values up to 110 and 19.5, respectively.
• Density functional theory and energy decomposition analyses reveal that electrostatic and dispersion interactions dominate the extraction mechanism, with van der Waals forces playing a major role.
• The selectivity of the ionic liquid increases with decreasing alkyl chain length, offering a tunable parameter for process optimization.
• The regenerated [EMIM][FeCl4] can be reused multiple times, demonstrating good recyclability and potential for industrial application.