Ternary Liquid–Liquid Equilibrium Data for the n-Heptane + Toluene + (Butane-1,4-diol or Glycerol) Systems at 298.2, 313.2, and 333.2 K and 0.1 MPa

Abstract

Liquid−liquid equilibrium (LLE) phase compositions (tie-line data) were experimentally measured and thermodynamically modeled for the systems nheptane + toluene + (butane-1,4-diol or glycerol) at 298.2, 313.2, and 333.2 K and 0.1 MPa. The direct analytical method was used to obtain the LLE data using a doublewalled glass cell. The phase equilibrium samples were quantitatively analyzed using gas chromatography. The ternary systems were successfully correlated using the NRTL and UNIQUAC thermodynamic models. The effectiveness of using butane-1,4-diol or glycerol as an alternative solvent to extract toluene from alkanes was evaluated by determining selectivity and solvent capacity. All systems studied were found to demonstrate type II ternary LLE behavior. The selectivity for the solvents studied was found to be comparable or superior to conventional solvents, but solvent capacities were poor, suggesting that the use of a cosolvent might be required to reduce solvent-to-feed ratios.

Liquid–Liquid Extraction of Toluene from n-Heptane Using Butane-1,4-diol + 2-Methyl-pentane-2,4-diol Liquid Mixtures

“…Subsequently, ternary LLE data for the systems n-heptane + toluene + (1,4-butanediol or glycerol) systems at (298.2, 313.2, and 333.2) K and 0.1 MPa were published. 20 The published experimental data confirmed that both 1,4-butanediol and glycerol are suitable for use as alternative solvents, but that implementation would be limited by low solvent capacities (distribution coefficients). Thereafter, preliminary experimental results indicated that 2methyl-2,4-pentanediol is not suitable for use as a solvent on its own as UNIFAC (LL) was found to incorrectly predict immiscibility between 2-methyl-2,4-pentanediol and n-heptane/toluene across the entire composition range.…”

“…Distribution coefficient comparison for the n -heptane (1) + toluene (2) + 1,4-butanediol (3) + 2-methyl-2,4-pentanediol (4) system with respect to toluene content in the alkane-rich phase at (a) 298.2 K and 0.1 MPa, and (b) 313.2 K and 0.1 MPa; *, pure 1,4-butandiol, ○, 3:1 ratio (this work); □, 1:1 ratio (this work); △, 1:3 ratio (this work).…”

“…The authors here previously published 20 the binary endpoints for toluene and 1,4-butanediol with literature comparison. Deviations may be due to different experimental measurement methods, GC conditions, as well as chemical purity.…”

“…In the absence of experimental data, UNIFAC (LL) was used to evaluate if the selectivity of all the solvents considered in the database was greater than unity. Subsequently, ternary LLE data for the systems n -heptane + toluene + (1,4-butanediol or glycerol) systems at (298.2, 313.2, and 333.2) K and 0.1 MPa were published . The published experimental data confirmed that both 1,4-butanediol and glycerol are suitable for use as alternative solvents, but that implementation would be limited by low solvent capacities (distribution coefficients).…”

Ternary Liquid–Liquid Equilibrium Data for the n-Nonane + o-Xylene + (Butane-1,4-diol or Glycerol) Systems at (298.2, 313.2, 333.2) K and 0.1 MPa

“…The direct analytical method was used to determine the equilibrium compositions. The cell was successfully used in previous studies ,, and the experimental procedure followed is as suggested by Alders . The cell was initially filled with 50 cm 3 of the solvent (butane-1,4-diol or glycerol) and 30 cm 3 of o -xylene.…”