Separation of 1-methoxy-2-propanol and water by organic solvent extraction based on quantum chemistry calculation and liquid-liquid equilibrium experiment

Abstract

1-Methoxy-2-propanol (PM) is extensively utilized in various industries, including coatings and semiconductor applications, owing to its low toxicity and affordability. However, PM + water mixture was an azeotrope with lowest boiling point, which presents a challenge in separating azeotropic mixture for industrial production. In this study, selectivity coefficient (Scal) and extractant loss (SL) were calculated using the open-source COSMO-SAC model by evaluating its activity coefficients at infinite dilution. Then, four extractants, butyl propionate, butyl acetate, 4-methyl-2-pentanone (MIBK) and isobutyl alcohol, were selected and verified. The ternary liquid–liquid equilibrium (LLE) data measurement for water + PM + butyl propionate/ butyl acetate/MIBK/ isobutyl alcohol systems were achieved at 298.15 K and 101.3 kPa. In addition, distribution coefficient (D) and selectivity coefficient (S) were calculated by the achieved data and used as indexes to further judge the performance of the extractants. Meanwhile, the widely adopted NRTL activity coefficient model was applied to regress LLE data, the corresponding root mean square deviation (RMSD) was less than 0.008. Accuracy of the regressed binary interaction parameters were evaluated through the Gibbs energy topology analysis. Besides, the possible extraction ability was investigated and confirmed at the micro level, of which the electrostatic potential (ESP), H-bond length, complexes’ interaction energy were explored. Further, the radial distribution function (RDF) was achieved by molecular dynamics (MD) simulation to further explain its interactions. This study can provide new theoretical guidance for organic extractants selection,then used for the separation of PM from azeotropic mixtures.