Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The liquid-liquid extraction of a nitrogen-containing aromatic "pyridine" and nitrogen/sulfur- containing aromatic "benzothiazole" from n-hexane and n-heptane using deep eutectic solvents (DESs) was studied in this work. A DES composed of methyltriphenylphosphonium bromide as hydrogen bond acceptor and ethylene glycol as hydrogen bond donor was selected for this separation. The main objective of this work was to assess whether the same DES can be applied for the denitrogenation "pyridine" and desulfurization "benzothiazole" of fuels. Moreover, the influence of n-alkane chain length on the extraction performance was studied. First, the solubility of the pyridine, benzothiazole, n-hexane and n-heptane in the DES was determined at 298.2 K and atmospheric pressure. Thereafter, the pseudo-ternary liquid-liquid equilibrium (LLE) data for the four systems: {n-hexane + pyridine + DES}, {n-heptane + pyridine + DES}, {n-hexane + benzothiazole + DES} and {n-heptane + benzothiazole + DES} were determined at atmospheric pressure and a temperature of 298.2 K. The assumption of a pseudo-ternary system was validated showing that none of the DES' constituents appears in the raffinate phase. From the LLE data the distribution ratios and selectivites of pyridine and benzothiazole were calculated. Both pyridine and benzothiazole were successfully extracted from their mixtures with n-hexane and n-heptane, with pyridine showing higher selectivity than benzothiazole and almost similar distribution ratios. Finally, The LLE data were correlated with the NRTL model using ASPEN Plus. The modeled results showed a strong correlation with the experimental results (RMSD (%) = 0.04 - 0.36).