Aqueous Solutions Of LiCl Research Articles

Structural modelling of the LiCl aqueous solution by the hybrid reverse Monte Carlo (HRMC) simulation

The reverse Monte Carlo (RMC) simulation is applied in the study of an aqueous electrolyte LiCl6H2O. On the basis of the available experimental neutron scattering data, RMC computes pair radial distribution functions in order to explore the structural features of the system. The obtained results include some unrealistic features. To overcome this problem, we use the hybrid reverse Monte Carlo (HRMC), incorporating an additional energy constraint in addition to the usual constraints of the pair correlation functions and average coordination. Our results show a good agreement between experimental and computed partial distribution functions (PDFs) as well as a significant improvement in pair partial distribution curves. This kind of study can be considered as a useful test for a defined interaction model for conventional simulation techniques

An extended formula of site-site Smoluchowski-Vlasov equation for electrolyte solution and infinitely dilute solution

Solvation dynamics is one of the central subjects in solution chemistry. Site-site Smoluchowski-Vlasov (SSSV) equation is a diffusion equation for molecular liquid to analytically calculate the van Hove time correlation function. However, the application has been limited to simple solvent system such as liquid water because of the difficulty in solving the equation. In this study, an extended treatment of SSSV equation is proposed, which is applicable to a wide range of solution systems including mixed solution, electrolyte solution, and infinitely dilute solution. The present treatment realizes computation of the dynamics in LiCl aqueous solution, NaCl aqueous solution, and infinitely dilute aqueous solution of Li(+) and Cs(+) at the molecular level.

Well‐Crystallized CO32–‐Type LiAl–LDH from Urea Hydrolysis of an Aqueous Chloride Solution

AbstractAn LiAl–layered double hydroxide (LiAl–LDH) was synthesized by autoclaving an aqueous solution of LiCl and AlCl3 with urea at 100–160 °C. Chemical and structural analyses show the resulting powder to be pure and well‐crystallized LiAl2(OH)6(CO3)0.5·yH2O (1 < y < 2). X‐ray powder diffraction reveals an apparent monoclinic C2/m symmetry and the presence of disorder in the arrangement of the layers. A detailed study of the reaction is also proposed, demonstrating that the LiAl–LDH does not form by homogeneous precipitation, but is the result of a one‐pot imbibition of the Al(OH)3 gel precursor by Li2CO3, favored by an increase in the pH.

No fragile-to-strong crossover in LiCl-H2O solution

Dynamics of water, especially in the temperature range of the "no man's land", remain a mystery. We present detailed study of dynamics in aqueous LiCl solution that is often considered as a model for bulk water. We employ broadband dielectric and light scattering spectroscopy in a broad frequency and temperature range. Our analysis reveals no sign of the fragile-to-strong crossover (FSC) neither in structural relaxation nor in translational motions. Our experimental results combined with a large selection of literature data lead to the clear conclusion-there is no FSC in dynamics of aqueous solutions at T ∼ 200-230 K. Instead, our analysis reveals appearance of the so-called excess wing at the high frequency tail of the structural relaxation peak. We discuss the localized nature of the relaxation process that contributes to the excess wing.

An Experimental Study of Simultaneous Heat and Mass Transfer in Falling Film and Bubble Mode Absorbers

In this study we investigated the lithium chloride–water vapor absorption process for falling film and bubble column absorbers under the same operating conditions. The results obtained were used to analyze the transfer process during the absorption of water vapor in an aqueous solution of LiCL. The performance of both absorbers was investigated for various solution flow rates and various gas flow rates. The results showed that bubble absorber is superior to the falling film mode for mass and heat transfer. Increasing the solution flow rates rarely affected the mass transfer but improved the heat transfer. As the gas flow rate increased, channels were formed in the film, which decreased the mass transfer in the falling film. But in the bubble column, increasing the gas flow rate influenced the boundary layer and therefore enhanced mass transfer. To evaluate the performance of mass and heat transfer, experimental results obtained were plotted as Nusselt and Sherwood numbers versus operating conditions for falling film and bubble modes, respectively, and the following empirical correlations were proposed: • For falling film mode: • For bubble mode:

Volumetric and Compressibility Studies of Salt Induced Hydrophobic Interactions in Pre–Micellar Region of Sodium Dodecyl Sulfate

Apparent molar volume, v and apparent molar adiabatic compressibility, of sodium dodecyl sulphate (SDS) in water and in 0.1 mol dm−3 aqueous solutions of LiCl and NaCl have been determined form density and speed of sound measurements. Both these parameters are found to be highly sensitive to the presence electrolyte, in the concentration range ∼0.001–0.01 mol kg−1, which corresponds to the pre—micellar region of SDS; it indicates extensive intermolecular hydrophobic interaction in the presence of electrolytes. From a comparison between the two electrolytes in affecting the v and values, NaCl is found to be more effective than LiCl. Above ∼0.01 mol kg−1, the data indicate that solution loses its hydrophobic hydration character due to the micellization of surfactant. The constancy in v and values further suggested that no structural—transition occurs under these experimental conditions. Classic structural hypothesis of hydrophobic hydration proposed by ‘Frank and Evans’ [1(a)] has been invoked to account for the negative v and values of SDS observed in aqueous solutions of LiCl and NaCl. All these observations are ultimately found to justify that salt induced hydrophobic interaction is much more effective than solvent induced, however, the contribution of hydration characteristic of the ions is also found to play its own role.

판형 열교환기식 제습기에서 LiCl 수용액의 열 및 물질전달 특성

Experimental investigations were carried out to examine the heat and mass transfer characteristics of LiCl aqueous solution for a plate heat exchanger type dehumidifier. Cooling dehumidification was adopted vertical type heat exchanger. Also non woven fabric is attached surface of the heat exchanger for spreadability of LiCl aqueous solution. Mass flow-rate of LiCl aqueous solution and concentration were selected as experimental conditions. Also, In this study, the effects of relative humidity of process air and velocity were investigated experimentally. As a result of heat transfer coefficient and mass transfer coefficient of were increased film reynolds number increased. heat transfer coefficient and mass transfer coefficient of LiCl aqueous solution were 0.14~0.24 kW/<TEX>$m2^{\circ}C$</TEX> and <TEX>$1.3{\times}10-63{\sim}6.2{\times}10-6$</TEX> m/s respectively.

Preparation and Electrochemical Properties of Li1+xAlxGe2-x(PO4)3 Synthesized by a Sol-Gel Method

NASICON-type Li1+xAlxGe2-x(PO4)3 solid state lithium ionic conductors were synthesized by a sol-gel method using citric acid and ethylene glycol. The obtained precursors were sintered at various temperatures and the NASICON-type single phase was observed in a range of x = 0–0.6. The highest electrical conductivity was obtained for Li1.4Al0.4Ge1.6(PO4)3 sintered at 900°C for 11 h in air. The total conductivity was 1.22×10−3 S cm−1 at 25°C, and the bulk and grain boundary conductivities were estimated by impedance profile analysis to be 1.70×10−3 and 4.30×10−3 S cm−1, respectively. Sintered pellets of Li1.4Al0.4Ge1.6(PO4)3 were immersed in distilled water, saturated LiCl aqueous solution, and a saturated LiCl and LiOH aqueous solution at 50°C for one week; X-ray diffraction patterns of these samples dried at 220°C under vacuum showed no significant change from that of the pristine sample. The electrical conductivity of Li1.4Al0.4Ge1.6(PO4)3 was decreased to 1.4×10−4 S cm−1 at 25°C by immersion in distilled water, while immersion in the saturated LiCl aqueous solution increased the conductivity to 4.95×10−3 S cm−1 at 25°C. Li1.4Al0.4Ge1.6(PO4)3 was stable in the saturated LiCl and LiOH aqueous solution. Li1.4Al0.4Ge1.6(PO4)3 was unstable in contact with Li metal and Li-In alloy, but was stable in contact with Li7Ti5O12.

Aqueous Lithium-Air Rechargeable Batteries

This article summarizes our research on aqueous lithium-air rechargeable batteries. Lithium-air batteries have a far higher energy density and lower material cost than lithium-ion batteries, so that they are now attracting growing attention as possible power sources for electric vehicles. Presently, two types of rechargeable lithium-air batteries have been developed; non-aqueous and aqueous types. The aqueous type has a lower specific energy density than the non-aqueous system, but overcomes some severe problems that must still be addressed for the non-aqueous type, such as lithium metal corrosion by water from air and the high polarization of electrode reactions. The key component of the aqueous lithium-air battery is a water-stable lithium metal electrode (WSLE). The WSLE developed in our laboratory consists of lithium metal covered with a lithium conducting polymer electrolyte and a lithium conducting water-stable solid electrolyte, which was successfully operated in a saturated LiOH and LiCl aqueous solution.

A Water Stable High Lithium Ion Conducting Li1.4Ti1.6Al0.4(PO4)3-Epoxy Resin Hybrid Sheet

A water stable and water penetration free high lithium ion conducting solid electrolyte sheet of Li1.4Ti1.6Al0.4(PO4)3 (LTAP) was prepared by hybridization with an epoxy resin. The LTAP fine powder was synthesized using a sol-gel method. A LTAP thin sheet (about 200 μm) was prepared via a tape casting method using a slurry of the mixture of the fine LTAP powder and a TiO2 fine powder (3 weight%). The tape-cast green sheet was sintered at 1060°C for 2 h. 2,2-bis(4-glycidyloxyphneyl)propane and 1,3-phenylenediamine in tetrahydrofuran was poured into the sintered LTAP sheet and was polymerized by heating at 150°C for 24 h. The obtained LTAP-epoxy hybrid sheet was water-penetration free, and the electrical conductivity was 4×10−4 Scm−1 at 25°C. This conductivity value is comparable to that of the sintered pellets reported previously. The lithium metal electrode protected with a lithium conducting polymer electrolyte, and the LTAP-epoxy hybrid electrolyte sheet showed no resistance change for 20 days in a saturated LiOH and LiCl aqueous solution. The water stable lithium metal electrode has a potential application for aqueous lithium air rechargeable batteries.

A Super High Lithium Ion Conducting Solid Electrolyte of Grain Boundary Modified Li1.4Ti1.6 Al0.4(PO4)3

A single phase NASICON-type lithium conducting solid electrolyte, Li1.4Ti1.6 Al0.4(PO4)3 (LTAP), was synthesized from the precursor prepared by a sol-gel method with citric acid. The bulk and grain boundary conductivity in open air (relative humidity; ca. 60%) of the LTAP sintered at 950°C was estimated to be 1.8 × 10−3 S cm−1 and 1.3 × 10−3 S cm−1 at 25°C, respectively, from the impedance profile analysis. The grain boundary resistance almost vanished following immersion in a saturated LiCl aqueous solution at 50°C for one week, and the total conductivity at 25°C increased from 7.5 × 10−4 S cm−1 to 9.2 × 10−3 S cm−1 in open air. The high conductivity has not changed for a long period in open air. The total conductivity of the immersed LTAP was dependent on the humidity in the atmosphere and was comparable to that of the pristine LTAP at as low humidity as in a glove box (dew point of ca. −80°C). The conductivity enhancement was explained by the formation of a low resistance LiCl-xH2O phase trapped in the grain boundaries of LTAP nanoparticles.

Neutron and X-ray diffraction measurements on highly concentrated aqueous LiCl solutions

New neutron and X-ray diffraction experiments have been performed on concentrated aqueous lithium chloride (LiCl) solutions under ambient conditions, as a function of the salt concentration. The concentration range covers a wide region, between ion-pair:water ratios of about 1:3 (which is about the solubility limit) and 1:15 (which is still rather high a concentration value). Data have been interpreted by means of the Reverse Monte Carlo structural modelling method. It has been established that meaningful ion–water and water–water partial radial distribution functions may be derived even from such limited amount of diffraction data, provided that the diffraction measurements and the method of interpreting them are chosen sensibly. The new data and their analyses suggest the presence of Li + cations with only 3 (or less) coordinated water molecules around them. At the highest concentration, one counter-ion has been found to penetrate into the first hydration sphere of the ions.

Stability and coagulation of natural diamond sols in LiCl solutions

The aggregate stability of natural diamond sols in LiCl aqueous solutions in the acidic region of pH values has been investigated using flow ultramicroscopy. The range of variations in parameters of structural forces for natural diamond in these solutions has been determined. The possibility of applying the Smoluchowski theory and the Muller theory of reversible coagulation to the description of the kinetics of coagulation and the equilibrium aggregate state of polydisperse diamond sols has been discussed.

Melting of the Precipitated Ice IV in LiCl Aqueous Solution and Polyamorphism of Water

Melting of the precipitated ice IV in supercooled LiCl-H(2)O solution was studied in the range of 0-0.6 MPa and 160-270 K. Emulsified solution was used to detect this metastable transition. Ice IV was precipitated from the aqueous solution of 2.0 mol % LiCl (or 4.8 mol % LiCl) in each emulsion particle at low-temperature and high-pressure conditions, and the emulsion was decompressed at different temperatures. The melting of ice IV was detected from the temperature change of the emulsified sample during the decompression. There was an apparently sudden change in the slope of the ice IV melting curve (liquidus) in the pressure-temperature diagram. At the high-pressure and high-temperature side of the change, the solute-induced freezing point depression was observed. At the low-pressure and low-temperature side, ice IV transformed into ice Ih on the decompression, and the transition was almost unrelated to the concentration of LiCl. These experimental results were roughly explained by the presumed existence of two kinds of liquid water (low-density liquid water and high-density liquid water), or polyamorphism in water, and by the simple assumption that LiCl dissolved maily in high-density liquid water.

Polarized Raman spectroscopic study on the solvent state of glassy LiCl aqueous solutions and the state of relaxed high-density amorphous ices

We measure polarized OH-stretching Raman spectra of the glassy lithium chloride aqueous solutions (LiClaq solutions) and the relaxed high-density amorphous ices (HDA). The totally OH symmetric vibrational mode around 3100 cm(-1) (g(1) mode) for the glassy LiClaq solutions of 14.3 mol% and the g(1) mode for the glassy LiClaq solution of 10.0 mol% seem to be similar to the g(1) mode for HDA at high pressure and the g(1) mode for HDA at 1 atm, respectively. This indicates that the solvent state of glassy LiClaq solution relates to the state of HDA and that the attenuation of the salt effect on water is equivalent to the attenuation of the pressure effect on water. This suggests a possibility that the hydration in electrolyte aqueous solution may relate to high-density liquid water.

Electrosurface properties and aggregation kinetics of natural diamond sol in LiCl solutions

Electrosurface properties and aggregation stability of natural diamond sol in aqueous LiCl solutions at pH 6.0 and 9.0 are studied. It is shown that the aggregation of particles occurs according to the barrierless mechanism in the potential minimum, the depth of which is determined by the radius of structural forces. The ranges of the parameters of the structural forces of natural diamond in these solutions are determined. It is revealed that the extension of the water boundary layers on natural diamond decreases with an increase LiCl concentration and pH.

Structural study of low concentration LiCl aqueous solutions in the liquid, supercooled, and hyperquenched glassy states

Neutron diffraction experiments on a solution of LiCl in water (R = 40) at ambient conditions and in the supercooled and hyperquenched states are reported and analyzed within the empirical potential structure refinement framework. Evidence for the modifications of the microscopic structure of the solvent in the presence of such a small amount of salt is found at all investigated thermodynamic states. On the other hand, it is evident that the structure of the hyperquenched salty sample is similar to that of pure low density amorphous water, although all the peaks of the radial distribution functions are broader in the present case. Changes upon supercooling or hyperquenching of the ion's hydration shells and contacts are of limited size and evidence for segregation phenomena at these states does not clearly show up, although the presence of water separated contacts between ion of the same sign is intriguing.

A Low-Temperature Crossover in Water Dynamics in an Aqueous LiCl Solution: Diffusion Probed by Neutron Spin−Echo and Nuclear Magnetic Resonance

Aqueous solutions of lithium chloride are an excellent model system for studying the dynamics of water molecules down to low temperatures without freezing. The apparent dynamic crossover observed in an aqueous solution of LiCl at about 220 to 225 K [Mamontov, JPCB 2009, 113, 14073] is located practically at the same temperature as the crossover found for pure water confined in small hydrophilic pores. This finding suggests a strong similarity of water behavior in these two types of systems. At the same time, studies of solutions allow more effective explorations of the long-range diffusion dynamics, because the water molecules are not confined inside an impenetrable matrix. In contrast to the earlier incoherent quasielastic neutron scattering results obtained for the scattering momentum transfers of 0.3 Å(-1) ≤ Q ≤ 0.9 Å(-1), our present incoherent neutron spin-echo measurements at a lower Q of 0.1 Å(-1) exhibit no apparent crossover in the relaxation times down to 200 K. At the same time, our present nuclear magnetic resonance measurements of the diffusion coefficients clearly show a deviation at the lower temperatures from the non-Arrhenius law obtained at the higher temperatures. Our results are consistent with a scenario in which more than one relaxational component may exist below the temperature of the dynamic crossover in water.

On the hydration structure of LiCl aqueous solutions: A Reverse Monte Carlo based combination of diffraction data and Molecular Dynamics simulations

Reverse Monte Carlo (RMC) calculations have been carried out on aqueous LiCl solutions at several concentrations, comparing experimental X-ray and neutron diffraction data with partial radial distribution functions (prdf) from Molecular Dynamics (MD) simulations based on conventional ion–ion, ion–water, and water–water pair potentials. The RMC calculations indicate that the hydration shell of the Li + ions could be even more structured than computer simulations predict, containing at high concentrations unusually few water molecules, of the order of 2 to 3. Concerning the consistency between the structures based on potential models and diffraction data: the ion–water partial radial distribution functions (prdf) from MD are found to be consistent with the experimental data whereas the water–water and ion–ion partials are more problematic. The most serious deficiency is that at high salt concentrations the O–O prdf cannot be made consistent with the present X-ray diffraction data.

Enzymatic Resolution of Ethyl α-Hydroxyphosphinates in a Modified Reaction Environment

The enzymatic resolutions of two racemic ethyl hydroxyalkane(P-phenyl)phosphinates were performed by both esterification and hydrolysis approaches. The first reaction was performed in anhydrous diisopropyl ether with triethylamine or pyridine as additives by using lipases from three different sources (Candida cylindracea, Aspergillus niger, and Mucor javanicus). The increase in enantioselectivity was observed when NEt3 was applied. The second reaction—lipase-catalysed hydrolysis of ethyl butyryloxyalkane(P-phenyl)phosphinates—was carried out by Candida cylindracea lipase in diisopropyl ether saturated with water or in aqueous solutions containing MgCl2, LiCl, or Triton X-100. The usefulness of biphasic systems consisting of diisopropyl ether and water or aqueous solution of MgCl2, LiCl, or Triton X-100 also were tested. The use of biphasic system in the presence of Triton X-100 resulted in the higher conversion of the substrates.