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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.

There is increasing focus on the replacement of commonly used solvents in the liquid−liquid extraction of aromatics with solvents that result in improved process economics as well as reduced risk in terms of health, safety, and environment. In this work, a selection of organic chemicals are proposed for further study as replacement solvents that meet the technological requirements for the process of aromatics extraction from alkanes and have not been conventionally considered previously for this application. There were 52,654 organic chemicals screened with the use of a search algorithm based on the process requirements in terms of physical properties, capacity, selectivity, and performance index. Nine organic chemicals were identified (not being previously considered) that met all the criteria imposed by the search algorithm. A risk assessment further screened the identified chemicals, filtering out the potential solvents with adverse impacts on health, safety, and environment. Process designs were developed with the use of ASPEN plus in order to ascertain the effects of solvent choice on process economics via the use of total annual costs. The screening process in this work produced significant insights due to its holistic approach. The incorporation of factors such as solvent price, solvent loss, utilities, capital costs, health, and environmental impact showed that several of the solvents identified may be sustainable and cost-effective alternatives to conventionally used solvents. This highlights the need for a robust and broad perspective in considering the impact of solvent choice.

Ternary liquid–liquid equilibrium (LLE) data were measured and correlated for the water + acetonitrile + (butan-1-ol or 2-methylpropan-1-ol) systems at (303.2, 323.2, and 343.2) K and 1 atm. A double-walled glass cell with the direct analytical method was used to measure the liquid–liquid equilibrium data. The phase equilibrium samples were analyzed and quantified using gas chromatography. The nonrandom two-liquid activity coefficient model was used to fit the experimental tie-lines using nonlinear least-squares regression of the data. Relative selectivity values for solvent separation efficiency were calculated from the tie-line data. The plait point for each temperature was estimated with the graphical Coolidge method.

Liquid−liquid equilibrium data were measured and correlated for the ternary systems acetonitrile + water + heptanoic acid and acetonitrile + water + nonanol at 323.15 K and 1 atm. The liquid−liquid equilibrium data were measured using the direct analytical method in a double-walled glass cell. The binodal curve was correlated using a modified Hlavatý equation, a β function, and a log γ equation. The experimental tie lines were correlated using the NRTL and UNIQUAC activity coefficient models. Fitting of both activity coefficient models was undertaken by nonlinear least-squares regression of the data. The tie-line data were used to derive the selectivity values for solvent separation efficiency.