Using Diaminomethanal as an Entrainer for the Separation of Isopropanol + Water Mixture

Diaminomethanal (an organic compound), was examined as entrainer for dehydration of isopropanol−water system by extractive distillation. Isobaric vapor−liquid equilibrium (VLE) data were studied for isopropanol−water−diaminomethanal system at 101.3 kPa, employing modified Othmer type still. The VLE data studied for the system comprising diaminomethanal were quite different from that of diaminomethanal-free system. The diaminomethanal represented a significant increase in the relative volatility of the isopropanol−water solution and led to termination of the azeotrope at a specific concentration. It was observed that the relative volatility for isopropanol−water mixture increases continuously with the increase in diaminomethanal concentration till 15.7 mol%. Results demonstrate that diaminomethanal is a functional entrainer for the separation of isopropanol−water mixture and 13 mol% of diaminomethanal concentration is enough to terminate the azeotrope. Furthermore, the experimental VLE data for ternary system were correlated by nonrandom two-liquid (NRTL) model and predicted values correlated with the experimental data very well. Further, the experimental data was verified for thermodynamic consistency by Wisniak–Tamir’s modification of McDermott-Ellis and Wisniak’s L-W thermodynamic consistency test.