Acetonitrile Dehydration via Extractive Distillation Using Low Transition Temperature Mixtures as Entrainers

Abstract

Low transition temperature mixtures (LTTMs) are versatile alternatives to ILs. They share many properties with ILs, so they become a suitable choice for entrainers in extractive distillation processes. In this study, glycolic acid and choline chloride in a 3:1 molar ratio (GC3:1) were synthesized and explored as entrainers for separation of acetonitrile + water azeotropic mixtures. Isobaric vapor−liquid equilibrium data for the pseudobinary mixtures of ACN + GC3:1 and water + GC3:1 were measured at atmospheric pressure (101.32 kPa). For the pseudoternary system ACN + water + GC3:1, also VLE data were measured at different GC3:1 mole fractions of 0.05, 0.1, and 0.15. The thermodynamic modeling of these systems was performed using the nonrandom two-liquid (NRTL) model. Furthermore, a study was conducted for synthesized GC3:1 recoverability. A good agreement were found between experimental data and predicted values for these systems. Results showed that LTTM (GC3:1) eliminated the acetonitrile + water azeotrope by manipulating the relative volatility of the acetonitrile + water mixture. Therefore, LTTM (GC3:1) can be concluded as an efficient entrainer for the separation of an acetonitrile + water azeotropic mixture by extractive distillation.

Natural Deep Eutectic Solvent-Mediated Extractive Distillation for Separation of Acetonitrile + Water Azeotropic Mixture

“…The performance of MC1:1 was compared with the two previously used glycolic acid-based DESs GC3:1 and GTM3:1 (glycolic acid + choline chloride in 3:1 molar ratio and glycolic acid + tertamethylammonium chloride in 3:1 molar ratio). , Although all the three DESs are capable of breaking the ACN + water azeotrope, out of all these, GTM3:1 presents the highest displacement from diagonal as shown in Figure . Nonetheless, the additional features of MC1:1 NADES adds value to be used as an entrainer.…”

“…Experimental VLE data for the ACN (1) + water (2) + DES (3) pseudo-ternary system at 101.3 kPa for 5 mol % DES concentration. For MC1:1 (■), for GTM3:1 (▲), for GC3:1 (●), and --- without DES.…”

“…Deep eutectic solvents were first used as an entrainer by Rodríguez et al , for separation of ethanol + water mixture. Later, Sharma et al used different deep eutectic solvents for the dehydration of aqueous ACN. , …”

“…Later, Sharma et al used different deep eutectic solvents for the dehydration of aqueous ACN. 20,21 In this study, NADES is prepared using two naturally occurring and biodegradable compounds, DL-malic acid and choline chloride. Malic acid and choline chloride metabolitebased NADES is an interesting eutectic system where the dicarboxylic acid facilitates dual-site hydrogen bond donor (HBD) interactions with choline chloride, 22 as a result of eutectic composition shifts to 1:1 unlike 2:1 in reline (urea/ choline chloride).…”

“…The performance of MC1:1 was compared with the two previously used glycolic acid-based DESs GC3:1 and GTM3:1 (glycolic acid + choline chloride in 3:1 molar ratio and glycolic acid + tertamethylammonium chloride in 3:1 molar ratio). 20,21 x 1 ′ vs T (red ○) and y 1 vs T (red •), MC1:1 = 10 mol %, x 1 ′ vs T (blue △) and y 1 vs T (blue ▲), MC1:1 = 15 mol %, x 1 ′ vs T (green ◇ ) and y 1 vs T (green ◆ ), and ---MC1:1 = 0%. Although all the three DESs are capable of breaking the ACN + water azeotrope, out of all these, GTM3:1 presents the highest displacement from diagonal as shown in Figure 8.…”