Gas solubility and rheological behavior study of betaine and alanine based natural deep eutectic solvents (NADES)

Abstract

Natural deep eutectic solvent (NADES) produced herein this work by mixing betaine and alanine with lactic acid and malic acid with 1:1 molar mixing ratios. Thermophysical properties including water content, thermal stability, density and gas solubility of CO 2 and N 2 were experimented at different isotherms for wide pressures range up to 50 bars. Moreover, detailed rheological experiments were conducted on the studied materials to obtain viscosity and deduce the dynamic flow behavior. A pressure driven physisorption mechanism was observed for the studied systems. Betaine based NADES materials showed superior carbon dioxide and nitrogen solubility when they are mixed with lactic acid. On the other hand, the rheological experimental results show shear-thinning effect in which the η is decreasing with shear rate at all temperatures. Low viscosity profiles NADES assure the less mass transfer resistance for lactic acid based NADES systems and it also confirmed that the high CO 2 and N 2 solubility for lactic acid based NADES samples.

The Entropy of Deep Eutectic Solvent Formation

“…For organic components that are solid at 298 K, the standard molar entropy is, according to Glasser and Jenkins [ 5 ], S 298° /J K −1 mol −1 = (774 ± 21)( v m /nm 3 ) + (57 ± 6) whereas for liquid components the values are [ 5 ] S 298° /J K −1 mol −1 = (1133 ± 7)( v m /nm 3 ) + (44 ± 2) Hence, for the components before forming the eutectic solvent the sum of the entropies is Σ A+D S 298° /J K −1 mol −1 = x A S 198°A /J K −1 mol −1 + x D S 198°D /J K −1 mol −1 The crucial quantity for the calculation of the entropy of a component of the DES is its density ρ , from which its molecular volume v m is derived in the manner of Equation (2). The densities and temperatures of fusion of some of the components of the DESs, not available in the Handbook [ 10 ], are from [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. The crystal structures of some of the components, from which the molecular volumes are calculated as v m = v uc / Z , where v uc is the unit cell volume and Z the number of formula units per unit cell, are from [ 18 , 19 , 20 , 21 , 22 , 23 , 24 ].…”

Kinetic study on the reaction of lauric acid with ethanol catalyzed by deep eutectic solvent based on cetyl trimethyl ammonium bromide

“…To alleviate these disadvantages, many scientists have proposed different kinds of ecofriendly and efficient catalysts (zeolites, ion exchange resins, solid acids, ionic liquids, and deep eutectic solvents (DESs)) . In the past decades, DESs have received a lot of attention both in academic fields and industrial applications due to the merits of nonflammability, easy separation, excellent solubility, and reusability .…”

“…DESs are generally obtained by mixing a hydrogen bond acceptor (HBA) (quaternary ammonium or phosphonium salt) and a hydrogen bond donor (HBD) (zinc chloride, benzoic acid, etc.) . Up to now, DESs have been exploited as solvents or catalysts in acid‐catalyzed reactions including esterification .…”

Kinetics of the reaction of ethanol and lauric acid catalyzed by deep eutectic solvent based on benzyltrimethylammonium chloride

“…Deep eutectic solvents (DESs) are proposed as a novel generation of ILs, or their alternatives, and they are of growing interest both in academic fields and industrial applications . DESs possess merits such as non‐flammability, easy separation, excellent solubility, reusability, etc.…”

“…A DES is usually made up of a hydrogen bond acceptor (HBA) (quaternary ammonium or phosphonium salt) and a hydrogen bond donor (HBD) (zinc chloride, benzoic acid, etc.) . To date, many kinds of DESs have been successfully exploited as catalysts and solvents for esterification reactions .…”