Flow of deep eutectic solvent-simulated fuel in circular channels: Part II—Extraction of dibenzothiophene

Different fuel types are usually produced in refineries containing various sulfuric compounds, which have acute negative impact on the ecosystem and human beings in general. Extractive desulfurization (EDS) is a recently used technology in the treatment of these compounds. This research targets investigating experimentally the desulfurization of liquid fuel using deep eutectic solvent (DES) in continuous liquid–liquid microchannels at room conditions. This was done using a circular 1.22 mm ID glass channel. The working fluids were simulated fuel with 200 ppm dibenzothiophene (DBT) and a DES composed of tetra-n-butylammonium bromide (TBAB) and polyethylene glycol 200 with a molar ratio of 1:2 respectively. The DES density and viscosity at room temperature are 1094 kg/m³ and 0.2 Pa.s respectively, while those of simulated fuel are 739.4 kg/m³ and 8 × 10⁻⁴ Pa.s respectively. The effect of initial DBT concentration in the simulated fuel, mixture velocity, DES volume fraction and channel length on extraction of the DBT was investigated. The results indicated that the percentage extraction of the DBT is independent of the initial DBT concentration while it increased with the increase in DES volume fraction and channel length. The results also showed that the DBT extraction is fluctuating with respect to mixture velocity. The highest DBT extraction for the investigated conditions, which was 47%, was achieved at a DES volume fraction of 0.5, 50 cm channel length and a mixture velocity of 0.2 m/s. Finally, the overall volumetric mass transfer coefficient decreased with increasing the residence time (channel length) and increased with increasing the mixture velocity.