Liquid-liquid extraction, COSMO-SAC predictions and process flow sheeting of 1-butanol enhancement using mesitylene and oleyl alcohol

The current work reports the extraction of 1-butanol from aqueous streams using low density solvents namely, mesitylene (ρ = 0.864 g/cm3) and oleyl alcohol (ρ = 0.849 g/cm3). The ternary Liquid-Liquid Equilibrium (LLE) studies for mesitylene (1) + 1-butanol (2) + water (3) and oleyl alcohol (1) + 1-butanol (2) + water (3) were conducted to explain the effectiveness of the two solvents. A type-I phase behavior with a large immiscible region was observed at T = 298.15 K and p = 0.1 MPa. High values of selectivity ranging from 400 to 2500 for mesitylene and 750-6500 oleyl alcohol were observed. Distribution coefficient values higher than unity indicated an easier diffusion of 1-butanol from aqueous phase to extract phase. It also confirmed a lower solvent to feed ratio for separation of 1-butanol from water. 1H NMR spectra indicated an aqueous rich phase free of solvent and while the contrary was observed in the solvent rich phase. Non-random two liquid (NRTL) and UNIversal QUAsichemical (UNIQUAC) models gave root mean square deviation (RMSD) in the range of 0.1-0.5% for both the systems. Further the predictions of the tie lines were also confirmed though the quantum chemical based COnductor like Screening MOdel Segment Activity Coefficients (COSMO-SAC) which gave RMSD in the range of 5%. Based on the selectivity values of 1-butanol at lower concentration, mesitylene was chosen as the recommended solvent for extraction. Thereafter a hybrid extraction process using Aspen Plus V8.8® was designed to carry out an optimized flowsheet concerning the recovery and recycle of butanol and mesitylene respectively.