Room-temperature ionic liquids phase states

Molten salt electrolyte systems comprise salts in the liquid state (molten), which form ionic phases and are highly ionically conductive, thus reaching specific conductivities comparable to those of room temperature concentrated aqueous solutions (0.1 < X < 10 Q -cur1) [160], These systems can be divided into two classes ... 

In the metals, the same type of interatomic force acts between atom of different metals that acts between atoms of a single element. We have already stated that for this reason liquid solutions of many metals with each other exist in wide ranges of composition. There, are many other cases in which two substances ordinarily solid at room temperature are soluble in each other when liquefied. Thus, a great variety of molten ionic crystals are soluble in each other. And among the silicates and other substances held by valence bonds, the liquid phase permits a wide range of compositions. This is familiar from the glasses, which can have a continuous variability of composition and which can then supercool to essentially solid form, still with quite arbitrary compositions, and yet perfectly homogeneous structure. 

AU equilibrium extractions were carried out at room temperature with 1 1 ionic liquid to aqueous phase ratio. The ionic hquid in its pure state absorbs a small amount of water depending on the initial nitric acid concentration that can vary from 17000 to 25000 ppm for 0.01 to 3 M nitric acid concentration, respectively. In the experiments a solution of 30 % (v/v) TBP in ionic liquids was prepared and equilibrated with the nitric acid solution at the required concentration by mechanical shaking at various time lengths. Saturation was confirmed by measuring the viscosity for both pure and saturated ionic liquid with a digital Rheometer DV-III Ultra (Brookfield). It was found that the ionic liquid was saturated after about 45 min shaking. Then, the two phases were separated and the pre-equihbrated... 

Room-temperature molten salts, namely ionic liquids, have proved to be a new class of promising solvents because of their good electroconductivity, nonflammability, thermal stability, nonvolatility, and reusability [1-3]. They consist of cations and anions without any solvent, and they are in a liquid state around room temperature. Typical examples of ionic liquids and their abbreviation are shown in Fig. 1. Ionic liquids are classified into hydrophilic and hydrophobic ones. Ionic liquids with BF4 or CFsSOs (TfO ) are hydrophilic. On the other hand, those with PFs or (CF3S02)N (Tf2N ) are hydrophobic. Hydrophobic ionic liquids do not dissolve into either water or organic solvents like ether and hexane. Therefore, they form three liquid phases. Hence, products can be separated by liquid-liquid extraction. This is one of big advantages of ionic liquids. Furthermore, if a combination of cation and anion is appropriately made, aprotic media having a wide electrochemical window... 

The ionic conductivity of the PEO electrolytes, therefore, strictly depends on both crystaflinity degree and Tg of the amorphous phase [70]. In particular, it is very low at room temperature (<10 O cm ) where the crystalline fraction of the polymer is predominant, but it abruptly increases around the melting temperature reaching 1 O cm above 80-90 °C, where the entire polymer is in a viscous liquid state. The research on SPEs ever pointed towards the enlargement of the amorphous fraction by means of several approaches. One of the most followed strategies was the choice of suitable Li salts and the identification of proper salt... 

Li M, Wang T, Pham PJ et al (2008) Liquid phase extraction and separation of noble organometallic catalysts by functionalized ionic liquids. Sep Sci Technol 43 828-841 Donato RK, Migliorini MV, Benvegnu MA et al (2007) The electrochemical properties of a platinum electrode in functionalized room temperature imidazoUum ionic liquids. J Solid State Electrochem 11 1481-1487... 

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