Liquid-liquid equilibria for separation of benzothiophene from model fuel oil: Solvent screening and thermodynamic modeling

The pollution of sulfur oxides to the environment is becoming more serious, so the separation of sulfides from fuel oil has great significance for environmental protection. In this paper, the separation of the sulfide benzothiophene from the model fuel oil was explored. The COSMO-SAC-UNIFAC model, σ-profile analysis, solvent power and selectivity were used to screen the suitable solvent. Sulfolane was selected as the suitable solvent to extract the benzothiophene from model fuel oil. The liquid–liquid equilibrium data for the system ( n -heptane + benzothiophene + sulfolane) was determined at 308.15, 318.15 and 328.15 K under 101.3 kPa. The extraction performance of the sulfolane was evaluated by separation factor and distribution coefficient. The NRTL and UNIQUAC models were adopted to correlate the LLE data with the calculated values of RMSD and ARD lower than 0.01. Furthermore, the binary interaction parameters were validated using a graphical user interface by MATLAB.