Sustainable technologies applied to energy-related applications should develop a pivotal role in the next decades. In particular, carbon dioxide capture from flue gases emitted by fossil-fueled power plants should play a pivotal role in controlling and reducing the greenhouse effect. Therefore, the development of new materials for carbon capture purposes has merged as central research line, for which many alternatives have been proposed. Ionic liquids (ILs) have emerged as one of the most promising choices for carbon capture, but in spite of their promising properties, some serious drawbacks have also appeared. Deep eutectic solvents (DESs) have recently been considered as alternatives to ILs that maintain most of their relevant properties, such as task-specific character, and at the same time avoid some of their problems, mainly from economic and environmental viewpoints. DES production from low-cost and natural sources, together with their almost null toxicity and total biodegradability, makes these sol...

Deep Eutectic Solvents: Physicochemical Properties and Gas Separation Applications

VLE predictions with the Peng–Robinson equation of state and temperature dependent kij calculated through a group contribution method

In the present work the oxidation of ferrocene, Fe(C5H5)2, to the ferrocenium cation, Fe(C2H5)2
 +, was examined in the solvents acetonitrile (ACN), acetone (ACE), N-methylformamide (NMF), N,N-dimethylformamide (DMF), N,N-dimethylacetanide (DMA), 3-pentanone (PEN), dimethyl sulfoxide (DMSO) and dichloromethane (DCM) over the temperature range from 248.15 to 298.15 K using the technique of cyclic voltammetry. The anodic (E
 pa) and the cathodic (E
 pc) peak potentials, as well as the corresponding anodic (i
 pa) and cathodic (i
 pc) peak currents, were obtained at different scan rates (0.02, 0.05, 0.08 and 0.10 V ·s–1). The half-wave potentials (E
 1/2) of the Fe(C2H5)2
 +/Fe(C5H5)2 couple in the investigated solvent media have been evaluated. The diffusion coefficients (D) have been calculated using the Randles-Sevcik equation. The effects of changing the scan rate, the temperature and properties of the solvent medium such as viscosity and donor number on the electrochemical behavior of ferrocene have been examined.

Cyclic Voltammetric Studies of Ferrocene in Nonaqueous Solvents in the Temperature Range from 248.15 to 298.15 K

Pyridinium N-phenolate betaine dyes.

In this work, we present a study on the physical and electrochemical properties of three new Deep Eutectic Solvents (DESs) based on N-methylacetamide (MAc) and a lithium salt (LiX, with X = bis[(trifluoromethyl)sulfonyl]imide, TFSI; hexafluorophosphate, PF6; or nitrate, NO3). Based on DSC measurements, it appears that these systems are liquid at room temperature for a lithium salt mole fraction ranging from 0.10 to 0.35. The temperature dependences of the ionic conductivity and the viscosity of these DESs are correctly described by using the Vogel–Tammann–Fulcher (VTF) type fitting equation, due to the strong interactions between Li+, X− and MAc in solution. Furthermore, these electrolytes possess quite large electrochemical stability windows up to 4.7–5 V on Pt, and demonstrate also a passivating behavior toward the aluminum collector at room temperature. Based on these interesting electrochemical properties, these selected DESs can be classified as potential and promising electrolytes for lithium-ion batteries (LIBs). For this purpose, a test cell was then constructed and tested at 25 °C, 60 °C and 80 °C by using each selected DES as an electrolyte and LiFePO4 (LFP) material as a cathode. The results show a good compatibility between each DES and LFP electrode material. A capacity of up to 160 mA h g−1 with a good efficiency (99%) is observed in the DES based on the LiNO3 salt at 60 °C despite the presence of residual water in the electrolyte. Finally preliminary tests using a LFP/DES/LTO (lithium titanate) full cell at room temperature clearly show that LiTFSI-based DES can be successfully introduced into LIBs. Considering the beneficial properties, especially, the cost of these electrolytes, such introduction could represent an important contribution for the realization of safer and environmentally friendly LIBs.

Deep eutectic solvents based on N-methylacetamide and a lithium salt as suitable electrolytes for lithium-ion batteries.

Using the Kirkwood–Buff theory of solutions, the preferential solvation of the N-methylacetamide molecule has been investigated in the binary and ternary mixtures containing N-methylacetamide (NMA), aliphatic alcohol and water. The results are compared with those obtained previously for N-methylformamide (NMF) and N,N-dimethylformamide (DMF). The thermodynamic investigations, based on the Kirkwood–Buff theory of solutions, lead to the unexpected conclusion that both NMA and DMF are solvated in the investigated binary and ternary mixtures in a very similar manner, but solvation of NMF differs from other amides. For all the
 investigated amides, the local mole fractions differ only slightly from the bulk ones—the deviations are only a few per cent or less. Moreover, for the {amide+methanol} binary mixtures, where
 amide=NMF, DMF and NMA, molecular dynamics calculations at xamide=0.518 were performed. From the obtained molecule–molecule radial distribution functions (rdf) and atom–atom rdf, it was possible to estimate the local mole fractions around the amide molecule, the orientation effects of molecules within the solvation shell, and a possibility of the formation of complexes. The general picture obtained from analysis of the molecular dynamics results is consistent with the deductions derived from thermodynamic data.

Preferential solvation of N-methylformamide, N,N-dimethylformamide and N-methylacetamide by water and alcohols in the binary and ternary mixtures

Excess volumes VE measured in a dilution dilatometer and total vapor pressures at the temperature 303.15 K are reported for (N-methylformamide + water), (N-methylformamide + methanol), and (N-methylformamide + ethanol) over the entire composition range. The total vapor pressure measurements were made by a modified static method. The excess molar volumes are negative for all the mixtures over the entire composition range; the vapor pressure measurements show only small negative deviations from ideality for these systems.

Jan Zielkiewicz

Papers

Preferential solvation of N-methylformamide, N,N-dimethylformamide and N-methylacetamide by water and alcohols in the binary and ternary mixtures

Excess Molar Volumes and Excess Gibbs Energies in N-Methylformamide + Water, or + Methanol, or + Ethanol at the Temperature 303.15 K

Excess volumes of (N,N-dimethylformamide+ethanol+water) at the temperature 313.15 K

(vapour + liquid) equilibria in (propan-1-ol + n-hexane + n-heptane) at the temperature 313.15 k

(vapour + liquid) equilibria of (n,n-dimethylformamide + water + propan-1-ol) at the temperature 313.15 k