Estimation of liquid‐liquid equilibrium of type 2 systems (water + valeric acid + monobasic ester or dibasic ester or alcohol) using SERLAS, SERLAS‐modified, and SERLAS‐integrated

Abstract

This paper studies liquid‐liquid equilibrium (LLE) of the type 2 systems (water + valeric acid + dibasic ester or monobasic ester or alcohol) at T = (298.2 ± 0.1) K and p = (101.3 ± 0.7) kPa. Equilibrium distribution of valeric acid onto (water + solvent) two‐phase system is better for more structured diethyl sebacate and ethyl caprylate as compared to less structured diethyl succinate, diethyl malonate, ethyl valerate, and isoamyl alcohol. The two‐phase envelope size and the tie line slope on the phase diagrams are varying as follows: ethyl caprylate > diethyl sebacate > ethyl valerate > diethyl succinate ≈ diethyl malonate > isoamyl alcohol. The SERLAS‐integrated (solvation energy relation for liquid associated systems‐integrated) molecular model with nine physical descriptors, originated from LSER (linear solvation energy relation) principles in conjunction with group‐contribution method, is proposed and applied to the prediction of type 2 LLE properties. By combining SERLAS with UNIFAC‐Dortmund, we are able to get along with a simultaneous impact of both methods for satisfactorily simulating type 2 phase behaviour so long as solvent effects are concerned. SERLAS, SERLAS‐modified, SERLAS‐integrated, and UNIFAC‐original models have been stringently tested for consistency in reproducing phase equilibrium properties with average deviations inferior to 28.8 %, 44.3 %, 21.3 %, and 30.4 %, respectively.