p-Toluenesulfonic Acid-Based Deep-Eutectic Solvents for Solubilizing Metal Oxides

Abstract

Combinations of p-toluenesulfonic acid monohydrate with different hydrogen-bond acceptors (i.e., choline chloride, tetraethylammonium chloride, tetrabutylammonium chloride, betaine hydrochloride, β-alanine, tetrabutylphosphonium chloride, ethylammonium chloride, methyltriphenylphosphonium bromide, and benzyltriphenylphosphonium chloride) were tested for deep-eutectic solvent (DES) formation. Only p-toluenesulfonic acid monohydrate:choline chloride, p-toluenesulfonic acid monohydrate:tetrabutylammonium chloride, and p-toluenesulfonic acid monohydrate:tetrabutylphosphonium chloride at a 1:1 molar ratio remained liquid at room temperature. The obtained deep-eutectic solvents were characterized by determining their density and viscosity as function of temperature, and their thermal operational window (i.e., decomposition temperature and melting point/glass transition temperature). Moreover, IR spectroscopy was used to elucidate the formation of hydrogen bonds. The solubility of different metal oxides in the DES p-toluenesulfonic acid monohydrate:choline chloride was experimentally determined. The effect of the hydrogen-bond donor:hydrogen-bond acceptor molar ratio (2:1, 1:1, and 1:2) on the metal oxide solubility was explored. A comparison was made with metal oxide solubilities in other choline chloride-based DESs and in acidic aqueous solutions.

Performance of p-Toluenesulfonic Acid–Based Deep Eutectic Solvent in Denitrogenation: Computational Screening and Experimental Validation

“…The TBPBr:PTSA 1:1 DES had denser properties compared to the TBPCl:PTSA 1:1 DES because of the denser anion type used. This result is in agreement with the literature, indicating that the salt type affects the DES's volumetric properties [23,24]. Higher HBD concentration in the DES increases the free molar volume, and therefore, the density increases.…”

“…The electrostatic interactions of the anion get weaker as the salt concentration decreases. Therefore, viscosity decreases [23].…”

Elucidating the Role of Hydrogen Bond Donor and Acceptor on Solvation in Deep Eutectic Solvents Formed by Ammonium/Phosphonium Salts and Carboxylic Acids

“…4 The majority of HBAs are quaternary ammonium or phosphonium salts, [5][6] while HBDs are typically comprised of metal halides, carbohydrates, amides, alcohols, or carboxylic acids. 3,7 DESs have been applied in a number of applications such as solvents in the extraction of metals, [8][9] bio-catalysis, [10][11][12][13] carbon dioxide capture, [14][15] biodiesel production, [16][17][18] extraction of natural compounds, [19][20][21] and desulfurization of fuels. [22][23][24] They have garnered considerable attention over the last decade and a half as potential alternatives to ionic liquids (ILs).…”

Review on Hydrometallurgical Recovery of Metals with Deep Eutectic Solvents

“…Thus, the use of acidic DES ( [57]) is favorable in view of metal leaching. As demonstrated by Rodriguez Rodriguez et al [44], the use of toluene sulfonic acid-based DES could be interesting, since the solubility of some metal oxides in the DES is higher than 120 g⋅L −1 , which is sometimes higher than a 3 mol⋅L −1 HCl solution. The effect of the DES structure was investigated in this study.…”