Lithium Halide Solutions Research Articles

Sorbent Properties of Halide-Free Ionic Liquids for Water and CO2 Perfusion

Aqueous solutions of lithium halides are state-of-the-art sorbents in sorption-based heat pump and heat storage devices, with the drawbacks of high corrosivity and limited natural resources of lithium. Halide-free ILs could be well-suited alternative sorbents and have been explored with isothermal titration calorimetry showing superior thermochemical performance. Here, we have explored the performance of selected halide-free ILs in perfusion measurements monitoring the uptake of water vapor and CO2 from an air stream with well-defined flow and humidity as a model for open sorption processes. We have determined the saturation vapor pressure of water in the corresponding water–IL mixtures and moreover determined the diffusion coefficients of molecular species in binary [EMIM][Ac]–water mixtures via pulsed-field-gradient nuclear magnetic resonance (PFG NMR) measurements. These, together with variation of the absorption rates with calorimetric monitoring, indicate that diffusion is approximately 3 orders of m...

Solvation structure around ruthenium(II) tris(bipyridine) in lithium halide solutions.

The solvation of the ruthenium(II) tris(bipyridine) ion ([Ru(bpy)3]2+) is investigated with molecular dynamics simulations of lithium halide solutions in polar solvents. The anion distribution around the [Ru(bpy)3]2+ complex exhibits a strong solvent dependence. In aqueous solution, the iodide ion forms a solvent shared complex with [Ru(bpy)3]2+, but not in the other solvents. Between Cl– and [Ru(bpy)3]2+, the strong hydration of the chloride ion results in a solvent separated complex where more than one solvent molecule separates the anion from the metal center. Hence, tailored solvation properties in electrolytes is a route to influence ion-ion interactions and related electron transfer processes.

Interaction of water with LiCl, LiBr, and LiI in the deeply supercooled region

The hydration mechanism of lithium halides was studied using time-of-flight secondary ion mass spectrometry as a function of temperature. The lithium halides embedded in thin films of amorphous solid water segregate to the surface at temperatures higher than 135-140 K, with efficiency increasing in the order of LiCl, LiBr, and LiI. A monolayer of LiCl and LiI adsorbed on the surface of amorphous solid water tends to diffuse into the bulk at 160 K. The infrared absorption band revealed that the aqueous lithium-halide solutions and crystals are formed simultaneously at 160 K; these phenomena are explicable as a consequence of the evolution of supercooled liquid water. The strong surfactant effect is inferred to arise from hydration of a contact ion pair having hydrophilic (lithium) and hydrophobic (halide) moieties. Furthermore, bulk diffusion of lithium halides might result from the formation of a solvent-separated ion pair in supercooled liquid water. The presence of two liquid phases of water with different local structures is probably responsible for the formation of these two hydrates, consistent with the calculated result reported by Jungwirth and Tobias[J. Phys. Chem. B 106, 6361 (2002)].

Solubility of Lithium Nitrate in Solutions of Lithium Halides

Solubility isotherms in LiNO3 – LiX – H2O (X = Cl, Br, I) systems at 298.15 K were measured for the first time with special regard to the retrograde solubility of lithium nitrate trihydrate. The compositions of solutions used as media in absorption refrigerators and heat pumps were compared with the results and subsequently discussed.

Experimental and theoretical studies of thermodynamics of lithium halide solutions – ethanol mixtures

The vapor pressures of lithium halide solutions in ethanol have been determined in the range of concentration from (0.01 to 2.0) mol · kg −1 at 298.15 K. The activity of solvent was obtained directly and the osmotic coefficients of solutions were then calculated. An accurate reference osmotic coefficient ( φ 0) was obtained in a more diluted solution at a reference molality, m 0 (=10 −3 kg · mol −1). The ionic activity coefficient, the excess, and the change in partial molal free energy of solutions were calculated by using Gibbs–Duhem equation. The values of osmotic coefficient that obtained in this work were fitted to MSA-NRTL and Pitzer’s models and the values of characteristic adjustable parameters were calculated. It is shown that the goodness and the overall quality of the fit for both models are excellent.

A mass spectrometric study of solvated clusters of ions and ion pairs generated from lithium halide solutions in polar solvents: Acetonitrile compared to methanol

Mass spectrometric study on cluster structure of solutions of lithium halides (LiX = LiBr and LiI) in acetonitrile is reported. Solvated ions Li +(CH 3CN) n, X −(CH 3CN) n, and salt clusters Li +(LiX) m(CH 3CN) n and X −(LiX) m(CH 3CN) n, were observed in the spectra. The mechanism of cluster formation is discussed in terms of a competition between solvation interactions and electrostatic interactions. This helps to explain the differences between clustering in methanol and acetonitrile, since the latter one has much larger dipole moment than the former one. Therefore appearance of solvated clusters, including the solvated salt clusters, is more favourable in methanol solutions' spectra.

Structure formation features of water and concentrated aqueous lithium halide solutions at low temperatures from the data of integral equation method

The structure of water and the influence of halide ions on the structure formation of concentrated LiX : H2O (1 : 5; X = Cl, Br, I) solutions at low temperatures were studied by the method of integral equations. Based on the results obtained, supercooling of pure water is expected to significantly enhance the tetrahedral ordering of its molecules, strengthen hydrogen bonding in the system, and decrease the number of the nearest-neighbor water molecules. The effects for the solutions on lowering the temperature include a partial restoration of the tetrahedral network of H-bonds of the solvent molecules, insignificant increase in the number of the nearest-neighbor water molecules, enhancement of the coordination ability of Li+ cation, strengthening of hydrogen bonding between anions and water molecules in the first hydration shell, increase in the number of solvent-separated ion pairs, and weakening of the temperature effect on these structural parameters in the following order of solutions: LiCl > LiBr > LiI. The probability of contact ion pair formation in the systems studied should appreciably decrease. The temperature should to a greater extent influence the associative ability of larger anions.

Thermodynamic properties of aqueous electrolyte solutions. 1. Vapor pressure of aqueous solutions of lithium chloride, lithium bromide, and lithium iodide

The vapor pressures of aqueous solutions of lithium halides were measured at different concentrations and temperatures from 303.15 to 343.15 K with use of a differential static method. Osmotic and activity coefficients were calculated and compared

Raman spectral studies of ion–molecular interactions of lithium bromide and lithium iodide with dimethyl sulphoxide

AbstractRaman spectra in the CH and SO stretching and SO bending regions are reported for solutions of lithium halides and tetrabutylammonium bromide (TBAB) in dimethyl sulphoxide (DMSO) and DMSO‐d6. The CD stretching band of DMSO‐d6 shows two components in solutions of TBAB with DMSO‐d6, whereas the CH stretching band of DMSO for solutions of LiX (X = Br and I) in DMSO show some broadening and asymmetry in the low‐frequency region. The SO stretching bands show changes in band shapes and band contours in solutions of electrolytes in DMSO. Fourier deconvolution of CH and SO stretching bands were carried out to gain more information regarding number of components present under the broad structured bands. All the solutions show a significant decrease in the intensity of the SO bending bands when compared with the neighbouring CS bending band. The results are discussed in terms of anion‐ and cation–molecular interactions with DMSO.

A novel isopiestic measurement of water activity in concentrated and supersaturated lithium halide solutions

Dans cette methode des gouttes microscopiques de solution aqueuse de LiBr et LiI a temperature ordinaire sont limitees electrodynamiquement dans une chambre close. La temperature de l'eau varie entre −74 et +21°C

Effect of temperature on the polarography and absorption spectra of cobalt(II) and nickel(II) in lithium halide solutions

Effect of temperature on the polarography and absorption spectra of cobalt(II) and nickel(II) in lithium halide solutions

The reduction of zinc(II) in concentrated lithium halide solutions

The reduction of zinc(11) in lithium halide solutions has been studied using a.c. and d.c. polarography over an electrolyte concentration range of 1-20m for lithium chloride and lithium bromide solutions, and 1-12m for lithium iodide solutions. The degree of reversibility for the reduction increased with increase in electrolyte concentration in the order LiI > LiBr > LiCl. Faradaic impedance techniques were utilized to evaluate the rates of the electron-transfer processes.

The polarography of cobalt(II) in aqueous solutions of lithium halides

The polarographic reduction of cobalt(II) in aqueous solutions of lithium halides is described. Lithium chloride and lithium bromide systems were studied over on electrolyte concentration range of 1–20 molal. It appears that the changes in E 1 2 and in the degree of polarographic reversibility accompanying changes in lithium halide concentration are more dependent upon the nature of the reducible species in solution, both with respect to charge and to structure than upon the nature of the particular halide present. The studies provide information on the possible state of aquation of the lithium ion.

Extraction of anions by a liquid cation-exchanger

The distribution ratio has been measured for the extraction of tracer quantities of a number of metals from aqueous solutions of HX or LiX (X = Cl, Br) by the liquid cation-exchangers 0·1 M dinonyl naphthalene sulphonic acid and 0·1 M lithium dinonyl naphthalene sulphonate in n-heptane. In several cases at high halide concentrations the partition behaviour shows marked deviation from that to be expected from the cation exchange process. The effect arises in instances where the metal is very strongly taken up by anion exchangers and anomalous extraction is always greater from lithium halide solution than from the corresponding aqueous halogen hydracid. The dinonyl naphthalene sulphonates occur in the organic layers in micellar form and the composition of such aggregates containing invaded supporting electrolyte and water has been ascertained. Spectrophotometric and stoichiometric measurements on lithium dinonyl naphthalene sulphonate in n-heptane extracts of macro-quantities of metals M(III) or M(II) from concentrated lithium halide solutions have demonstrated the presence of anionic metal halide complexes in organic phases. Slope-analysis of partition data obtained with the metals present at trace concentration gives results in agreement with these conclusions, and the anomalous extraction behaviour can be formulated as involving equivalent exchange of a complex metal-halide anion with invaded halide associated with micelles in the organic medium.

The vibrational spectra of the halides and complex halides of the Group IIBelements. Part II. A Raman spectroscopic study of the systems HgX2–LiX (X = Cl, Br) in aqueous and tri-n-butyl phosphate solutions

The Raman spectra of aqueous solutions containing varying proportions of mercuric halide and lithium halide, and of the tri-n-butyl phosphate (TBP) extracts of these aqueous solutions are reported. Although the HgX3– anion is not observed in aqueous solution, it seems to be the most stable species in the tri-n-butyl phosphate extracts. The extraction of mercury(II) from aqueous lithium halide solutions into tri-n-butyl phosphate thus differs from the previously reported extraction from concentrated halogen acids. Expressions are derived for the distribution ratio of mercury(II) for the individual extraction of HgX42– and HgX3–, and the dependence of the distribution ratios on the lithium ion, halide ion, and tri-n-butyl phosphate concentrations is verified experimentally.