Measurement and Thermodynamic Modeling of Liquid-Liquid Equilibrium Data for Ternary Systems (Water plus Formaldehyde plus Methyl Isobutyl Ketone/Cyclohexanone) at Different Temperatures

To explore the separation of formaldehyde from its aqueous solution, the liquid-liquid equilibrium data for the systems (water + formaldehyde + methyl isobutyl ketone/cyclohexanone) were measured at 303.15, 313.15, and 323.15 K in 101.3 kPa. The separation effect was judged by the separation factor and the partition coefficient. The S values of methyl isobutyl ketone and cyclohexanone are greater than unity, and the S and D values of cyclohexanone are greater than methyl isobutyl ketone, indicating that cyclohexanone is a suitable extractant compared with methyl isobutyl ketone. The reliability of the measured data is evaluated by Hand and Othmer-Tobias equations, and the R-2 values of the two equations are close to unity. The universal quasi-chemical theory and nonrandom two-liquid theory models were applied to fit the tie-line data of the investigated mixtures with a root mean square deviation lower than 0.01. Moreover, the binary interaction parameters were validated using a topology of Gibbs energy of mixing surface analysis.

Automated summary

In this study, the separation of formaldehyde from its aqueous solution was investigated. The separation effect was evaluated using the separation factor and partition coefficient. It was found that cyclohexanone is a suitable extractant compared to methyl isobutyl ketone. The experimental data was fitted using the quasi-chemical theory and nonrandom two-liquid theory models, with good agreement. The binary interaction parameters were validated using a topology of Gibbs energy analysis.