LiOH Solution Research Articles

Electrolytical properties of solutions of lithium hydroxide at high temperatures and pressures

This paper presents experimental and calculated data on dissociation constants and specific and molar (limiting) electric conductivity of aqueous and vapor solutions of LiOH at concentrations ranging from 7.24 × 10−7 to 3.34 × 10−1 mol/kg and temperatures ranging from 298.15 to 646.65 K on the saturation line. To extend the capabilities of estimating the physico-chemical processes at lithium water chemistry under conditions of high temperatures, the graphical dependence of the specific conductivity of aqueous solutions of LiOH on concentration and temperature is given, which shows the advisability of determining concentration from a specific conductivity in the region of a maximum of curves describing the dependence of the specific conductivity on temperature. The values of pH and pOH of solutions of LiOH within the indicated range of concentrations and temperatures have been calculated. It is shown that on dosing LiOH solutions into the boiler water at concentrations from 7.24 × 10−7 to 8.7 × 10−6 mol/kg the values of pH for LiOH and H2O are virtually the same at the temperature of 553 K, which scarcely affects the formation of protective lithium-ferrite film. Five relationships for calculating pH at different values of concentration and specific conductivity of LiOH solutions on isotherms ranging from 373.15 to 616.35 K have been worked out.

Chemical Speciation of Neptunium(VI) under Strongly Alkaline Conditions. Structure, Composition, and Oxo Ligand Exchange

Hexavalent neptunium can be solubilized in 0.5-3.5 M aqueous MOH (M = Li(+), Na(+), NMe4(+) = TMA(+)) solutions. Single crystals were obtained from cooling of a dilute solution of Co(NH3)6Cl3 and NpO2(2+) in 3.5 M [N(Me)4]OH to 5 °C. A single-crystal X-ray diffraction study revealed the molecular formula of [Co(NH3)6]2[NpO2(OH)4]3·H2O, isostructural with the uranium analogue. The asymmetric unit contains three distinct NpO2(OH)4(2-) ions, each with pseudooctahedral coordination geometry with trans-oxo ligands. The average Np═O and Np-OH distances were determined to be 1.80(1) and 2.24(1) Å, respectively. EXAFS data and fits at the Np L(III)-edge on solid [Co(NH3)6]2[NpO2(OH)4]3·H2O and aqueous solutions of NpO2(2+) in 2.5 and 3.5 M (TMA)OH revealed bond lengths nearly identical with those determined by X-ray diffraction but with an increase in the number of equatorial ligands with increasing (TMA)OH concentration. Raman spectra of single crystals of [Co(NH3)6]2[NpO2(OH)4]3·H2O reveal a ν1(O═Np═O) symmetric stretch at 741 cm(-1). Raman spectra of NpO2(2+) recorded in a 0.6-2.2 M LiOH solution reveal a single ν1 frequency of 769 cm(-1). Facile exchange of the neptunyl oxo ligands with the water solvent was also observed with Raman spectroscopy performed with (16)O- and (18)O-enriched water solvent. The combination of EXAFS and Raman data suggests that NpO2(OH)4(2-) is the dominant solution species under the conditions of study and that a small amount of a second species, NpO2(OH)5(3-), may also be present at higher alkalinity. Crystal data for [Co(NH3)6]2[NpO2(OH)4]3·H2O: monoclinic, space group C2/c, a = 17.344(4) Å, b = 12.177(3) Å, c = 15.273 Å, β = 120.17(2)°, Z = 4, R1 = 0.0359, wR2 = 0.0729.

ChemInform Abstract: Shape‐Controlled Synthesis of LiMnPO4 Porous Nanowires.

AbstractLiMnPO4 porous nanowires are prepared from solutions of MnSO4, H3PO4, and LiOH in a mixture of glycol and water (autoclave, 140 °C, 10 h).

High-performance LiMn2O4 with enwrapped segmented carbon nanotubes as cathode material for energy storage

This paper reports a spinel-type LiMn2O4/carbon nanotube (CNT) composite cathode material with high electrochemical performance for energy storage applications. The composite material is prepared by hydrothermal reaction between birnessite MnO2/multiwalled carbon nanotube (MWCNT) composite and LiOH solution, followed by heat treatment at 700 °C in air atmosphere, where the MnO2/MWCNT precursor is obtained by in situ redox reaction between KMnO4 solution and MWCNTs. The heat treated LiMn2O4/CNT composite material consists of well-crystallized spinel LiMn2O4 with small amount of enwrapped segmented carbon nanotubes, which is confirmed by X-ray diffraction and transmission electron microscopy. Electrochemical experimental results demonstrate that the LiMn2O4/CNT composite material heat treated for 8 h exhibits high specific capacity and excellent high-rate capability in 5 M LiNO3 aqueous electrolyte. The (LiMn2O4/CNT)/5 M LiNO3/activated carbon hybrid supercapacitor with this LiMn2O4-based composite material as the cathode presents excellent high-power capability and good charge/discharge cyclability.

Synthesis of Li/Al LDH using aluminum and LiOH

The synthesis of Li/Al layered double hydroxide (LDH) within the ternary system of LiOH–Al–H2O was investigated to determine the feasibility of a one-step synthetic process and the optimal yield composition for the process. The dissolution of Al metal in LiOH solutions was spontaneous and resulted in the generation of H2 gas and heat. Pure Li/Al LDH precipitate was obtained when the Al/Li molar ratio was between 0.1 and 2 and was independent of the LiOH concentration. The yield of Li/Al LDH was correlated with the initial amounts of LiOH and Al in the system and inversely correlated to the quantity of water. However, the Al metal could not be completely dissolved if there was not enough water content due to its consumption in the reaction. The optimal yield of Li/Al LDH, as defined by the efficient conversion from Al and LiOH to Li/Al LDH, was obtained with a LiOH concentration=3molkg−1 and an Al/Li molar ratio=2. The reaction mechanism involves the dissolution of the Al metal in LiOH and the formation of aluminate ions in solution. The aluminate ion and the hydrated Li+ ion subsequently form an ion pair, and the polarizing effect of the Li+ on the water in its hydration shell leads to the acid hydrolysis of the aluminate ion and the formation of Li/Al LDH. This study demonstrated a synthetic process for Li/Al LDH with a high anion exchange capacity. This synthetic process will have additional economical and environmental benefits if recycled Al metal can be used in the synthesis and the evolved hydrogen gas and heat from the process can be further utilized.

Superadsorption of LiOH solution on chitosan as a new type of solvent for chitosan by freezing/blasting

The adsorption behavior and mechanism of chitosan in aqueous LiOH solution was studied systemically. The results showed that the adsorption of chitosan was mainly due to the breakage of its hydrogen bonds, which were destroyed by the reaction of LiOH with the acetyl and the hydroxyl groups of chitosan. Low temperature also played a crucial role in the adsorption of chitosan. The adsorption of chitosan decreased with increased DD. The adsorption ratio of LiOH to chitosan (nLiOH/nCS) increased linearly while the adsorption ratio of water to chitosan (nH2O/nCS) decreased with the increased DD. All chitosans reached their maximal swelling degree when the concentration of LiOH was 4.8wt%. Chitosan was stable in LiOH aqueous solution. The LiOH solution may be a potential favorable solvent for chitosan.

Stability of Nb-Doped Cubic Li7La3Zr2O12 with Lithium Metal

The garnet-type Nb-doped cubic lithium ion-conducting solid Li6.75-xLa3Zr1.75Nb0.25O12–0.5x (LLZ-Nb) was prepared with 0.46 wt% Al2O3 using a sol-gel precursor. LLZ-Nb sintered at 1,150°C for 36 h exhibited a bulk conductivity of 6.13 × 10−4 S cm−1 and a grain boundary conductivity of 7.76 × 10−3 S cm−1 at 25°C. The cell resistance of Li/LLZ-Nb/Li was gradually increased with storage time over 5 months. The increase in cell resistance was attributed to both the grain boundary and interfacial resistance between LLZ-Nb and the lithium electrode. The Li/LLZ-Nb/Li cell showed a short-circuit for 280 s polarization at 0.5 mA cm−2 and no short-circuit for 41 h polarization at 0.1 mA cm−2. LLZ-Nb was stable in saturated LiOH and LiCl aqueous solution.

Stability of NaSICON-type Li1.3Al0.3Ti1.7P3O12 in aqueous solutions

The chemical and electrochemical stability of high-purity lithium aluminum titanium phosphate (LATP) as a solid state electrolyte and physical separator in aqueous electrochemical cells was evaluated using LiOH, LiCl, LiNO3, and LiCOOCH3 salts as the Li source. LATP, with formula Li1.3Al0.3Ti1.7P3O12, was found to be most stable between pH 8–9, with the longest cell operating continuously at 25 mA cm−2 for 625 h at 40 °C in LiCOOCH3. Biaxial strength was 191 ± 11 MPa when tested in mineral oil, 144 ± 13 MPa as measured in air, and 26 ± 7 MPa after exposure to deionized water, suggesting that LATP undergoes stress-corrosion cracking. After exposure to LiOH, the strength was 76 ± 19 MPa. The decrease in strength was observed despite there being no measurable change in a.c. impedance spectra, x-ray diffraction, or sample mass, suggesting phosphate glasses at grain boundaries. At pH values outside of the 7–10 range, eventual membrane degradation was observed in all aqueous systems under electrochemical conditions. While LATP was surprisingly resistant to static corrosion in a hot, aqueous LiOH solution, electrochemical degradation was observed at the cathode due to subsurface pitting. Strength measurements were more instructive than impedance measurements in detecting this degradation.

Synthesis and Optical Properties of ZnO Nanoparticles in Submicron PS Hollow Reactors

ZnO nanoparticles were first encapsulated in submicron PS hollow microspheres through two-step swelling process of core-shell structured PMMA/PS (PMMA: polymethyl methaorylate) microspheres in acid-alkali solution, and the ZnO precursors, i.e. the ethanol solutions of (CH3COO)2Zn and LiOH. The transmission electron microscope, X-ray diffraction, and thermogravimetric analysis results show that the feeding order of ethanol solutions of (CH3COO)2Zn and LiOH in the second swelling step has great influence on the loading efficiency and the size of ZnO nanoparticles, but little on their crystal form. The photoluminescence and UV-Vis absorption behavior of ZnO/PS microspheres show that the PS shell can effectively avoid the fluorescence quenching effect.

A rechargeable lithium–air battery using a lithium ion-conducting lanthanum lithium titanate ceramics as an electrolyte separator

We successfully prepared the perovskite-type lanthanum lithium titanate (LLTO) ceramics electrolytes with high total lithium ion conductivity of 3–5 × 10−4 S cm−1 at 300 K. The high total conductivity is attributed to the elimination of resistive grain boundary by the grain growth. Using the electrolyte as a separator, a rechargeable aqueous-type lithium/air cell which composed of Li metal/Li organic electrolytes/LLTO ceramics tube/LiOH aq/O2 carbon electrodes was developed and the stable discharge/charge behaviors were confirmed. Owing to the low porosity and the stability to alkaline aqueous solution of LiOH as well as high ionic conductivity, the lithium ion-conducting lanthanum lithium titanate ceramics is suitable for an electrolyte separator for aqueous-type rechargeable lithium/air batteries.

ChemInform Abstract: Improving the Performance of High Capacity Li‐Ion Anode Materials by Lithium Titanate Surface Coating.

AbstractSnO2@Li4Ti5O12 core—shell composite particles are prepared by deposition of titania on hollow SnO2 nanoparticles followed by dispersion of the titania‐coated hollow tin oxide nanoparticles in aqueous LiOH solution (autoclave, 180 °C, 20 h).

Carbon electrode with perovskite-oxide catalyst for aqueous electrolyte lithium-air secondary batteries

Carbon electrodes with perovskite-type oxide catalysts were investigated as air electrodes for aqueous lithium-air secondary batteries. The system consisted of a water-stable lithium electrode, an aqueous solution of saturated LiOH with 10 M LiCl as electrolyte, and a carbon black air electrode with perovskite catalyst additive. The stability, oxygen reduction and oxygen evolution catalytic activity of the La0.6Ca0.4Co0.8Fe0.2O3, La0.8Sr0.2Fe0.8Mn0.2O3, and La0.6Sr0.4Co0.2Fe0.8O3 perovskite-type oxides were examined in the LiOH–LiCl electrolyte. The perovskite-type oxides were stable in this solution and the oxygen reduction and evolution overpotential on the carbon black substrate was decreased by addition of these perovskite-type oxides. No chlorine evolution was observed during the oxidation reaction on carbon black with the perovskite-type oxides in the LiOH–LiCl electrolyte. The results indicate that carbon black with perovskite-type oxide additives is a potential candidate for the air electrode in the aqueous electrolyte lithium-air rechargeable batteries.

Millimeter-sized spherical ion-sieve foams with hierarchical pore structure for recovery of lithium from seawater

Millimeter-sized spherical ion-sieve foams (SIFs) were prepared from spinel lithium manganese oxide (LMO) via a combined process of foaming, drop-in-oil, and agar gelation to recover the lithium from natural seawater. The spinel structure of the fabricated SIFs was induced by H+–Li+ ion exchange after acid treatment, and the SIFs were found to exhibit hierarchical trimodal pore structure. Small and large bimodal mesopores were formed from the acid treatment-induced agar removal, and macropores from the bubble-template. Increasing agar content during the fabrication process led to an increase in the specific surface area and mesopore volume of the SIFs, but a decrease in the macropore volume. The amount of lithium adsorption in the LiOH solution was significantly decreased with increasing agar content during the fabrication process, probably because the SIFs fabricated with lower agar content possessed more open pores, which in turn increased the contact probability with the hierarchical structure developed in the inner parts of the SIFs. The SIFs with the lowest agar content exhibited greatest lithium adsorption capacity in natural seawater of 3.4mgg−1, and the adsorption and desorption efficiency were almost unaffected even after five adsorption–desorption cycles.

Corrosion of zirconium alloys in concentrated lithium hydroxide solutions

The accelerated corrosion of two alloys used as fuel cladding material, such as Zircaloy-4 and Zr–1%Nb has been studied in concentrated lithium hydroxide (LiOH) solutions at high temperature and pressure. Zr–2.5%Nb pressure tube material (PT) was also tested in order to analyze the influence of the amount of β-Zr phase on the accelerated corrosion of the Zr–Nb alloys. The microstructure of Zircaloy-4 consisted of α-Zr equiaxed grains whereas that of Zr–2.5%Nb (PT) and Zr-1%Nb alloys showed a two phase (α-Zr+β-Zr) microstructure.Autoclaving tests were performed in LiOH solutions with concentrations ranging from 0.1M to 1M for 16h at 343°C, and also in steam at 400°C. The extent of corrosion was evaluated through the weight gain and visual appearance of the oxide. Measurements included hydrogen uptake and oxide thickness. Optical microscopy observations of the hydride distribution were also made on the specimens.Results showed that Zircaloy-4 suffered accelerated corrosion at 0.7M and 1MLiOH concentrations with high hydrogen uptakes (∼50%). For these LiOH concentrations, although the Zr–2.5%Nb (PT) and Zr–1%Nb alloys showed weight gains higher than the threshold value established for the “transition”, their hydrogen uptakes were low (∼1%). This behavior indicates that at the early stages of the corrosion process in these solutions, an oxide barrier layer may be present at the metal/oxide interface of these Zr–Nb alloys. The lower amount of β-Zr phase in Zr–1%Nb improves the characteristics of the oxide layer in relation to that formed on Zr–2.5%Nb and does not affect the hydrogen uptake.

Rapid determinations of saccharides in high-energy drinks by short-capillary electrophoresis with contactless conductivity detection

The methodology for separations of saccharides in standard electrophoretic systems has been transferred to the short-capillary electrophoresis format. The laboratory-designed apparatus used employs a quartz capillary with an internal diameter of 10 μm, a total length of 10 cm, and an effective length of 4 cm, in combination with contactless conductivity detection. It has been applied to separations of neutral mono- and disaccharides. The saccharides are separated in the anionic form, in solutions of alkali hydroxides, namely, KOH, NaOH, and LiOH. The separation of a model mixture of five saccharides (sucrose, lactose, glucose, fructose, and ribose) takes less than 1 min, the LOD equaling 15, 35, 19, 17, and 24 mg L(-1) and the LOQ equaling 52, 117, 63, 53, and 79 mg L(-1) for sucrose, lactose, glucose, fructose, and ribose, respectively. The technique developed has been used to determine sucrose, glucose and fructose in high-energy drinks. The separation is finished within less than 50 s; the saccharide contents determined are identical with the declared values within the reliability interval in most cases, the RSD value being mostly less than 2%. In general, the separation system developed is very convenient for rapid analyses of large sets of similar samples, e.g., in product quality control or environmental monitoring.

Effect of alkali species on synthesis of K-F zeolitic materials from paper sludge ash for soil amendment

Zeolitic material including zeolite K-F (KAlSiO4·1.5H2O) with soil amendment properties was synthesized at 90°C from paper sludge ash in KOH–NaOH and KOH–LiOH mixtures. The total alkali concentration in each solution was maintained at 4mol/L and the relative amounts of the cationic species (K+/Na+ and K+/Li+) were varied. Zeolite K-F crystal could be obtained in KOH–NaOH solutions with Na/(Na+K) ratios lower than 0.5 or KOH–LiOH solutions with Li/(Li+K) molar ratios lower than 0.25, while hydroxysodalite (Na6Al6Si6O24·8H2O) and katoite (Ca3Al2(SiO4)(OH)8) were formed at other cation molar ratios in each mixture. The observed concentrations of Si and Al in the solution during the reaction explain the synthesis of reaction products with soil amendment properties. The properties of a product intended for K+ release depend on formation of an amorphous gel and zeolite K-F, while that for Ca2+ release depends on formation of an amorphous gel and calcium hydrate minerals, such as katoite. The formation of zeolite K-F in a KOH–LiOH solution with Li/(Li+K) ratio=0.25 is faster than that in KOH alone and the product with good properties, high cation exchange capacity and high released amount of Ca2+, for soil amendment could be obtained.

Mechanism of Np(VI) oxidation with ozone in alkaline solutions

Bubbling of an ozone-oxygen mixture containing 0.1–0.5 vol % O3 at a rate of 15–20 l h−1 through 13 ml of a 2 × 10−5−1 × 10−4 M solution of Np(VI) in 0.1 and 1 M LiOH leads to the formation of Np(VII). The initial rate increases approximately in proportion to [Np(VI)] and [O 3 gas ]0.5. Up to 80% of Np(VI) is oxidized at maximum. At the O3 concentration in the gas phase increased to 1–4 vol %, Np(VI) is oxidized completely. Under the same conditions, Np(VI) in a concentration of (1–5) × 10−3 M is oxidized to almost 100%. Analysis of published data and additional experiments on the reaction of O3 with Np(VI) ions in LiOH solutions allow a conclusion that the ozonation involves the reactions O3 + OH− = HO 2 − + O2, O3 + HO 2 − + OH− = O 3 − + O 2 − + H2O, and O3 + O 2 − = O 3 − + O2, followed by O 3 − + NpO2(OH) 4 2− = O2 + NpO4(OH) 2 3− + H2O. In addition, HO 2 − reduces Np(VII) and Np(VI) and reacts with O 3 − . Certain contribution is made by the reaction Np(VI) + O3 = Np(VII) + O 3 − . The dependence of the Np(VII) accumulation rate on [O 3 gas ]0.5 was interpreted in terms of the concept of a heterogeneous-catalytic process.

Elaboration and characterization of a free standing LiSICON membrane for aqueous lithium–air battery

In order to develop a LISICON separator for an aqueous lithium–air battery, a thin membrane was prepared by a tape-casting of a Li1.3Al0.3Ti1.7 (PO4)3–AlPO4 based slip followed by a sintering step. By optimizing the grain sizes, the slip composition and the sintering treatment, the mechanical properties were improved and the membrane was reduced to a thickness of down to 40 μm. As a result, the ionic resistance is relatively low, around 38 Ω for a 55 μm membrane of 1 cm2. One side of the membrane was coated with a lithium oxynitrured phosphorous (LiPON) thin film to prevent lithium metal attack. Lithium metal was electrochemically deposited on the LiPON surface from a saturated aqueous solution of LiOH. However, the ionic resistance of the LiPON film, around 67 Ω for a 1.2 μm film of 1 cm2, still causes an important ohmic loss contribution which limits the power performance of a lithium–air battery.

On the pH control at supercritical water-cooled reactor operating conditions

Abstract Application of LiOH (aq) for the pH control of the coolant at supercritical water-cooled reactor (SCWR) operating conditions is examined. The pH values of dilute aqueous LiOH solutions ( c = 10 −6 –10 −2 mol/kg) are calculated based on recently reported simulation data for the association constant of LiOH at supercritical water conditions [Plugatyr, A., Carvajal-Ortiz, R. A., Svishchev, I. M., 2011. Ion-pair association constant for LiOH in supercritical water. J. Chem. Eng. Data 56(9), 3637–3642]. The results indicate that at the operating pressure of the SCWR of 25 MPa, addition of LiOH to the coolant will provide adequate pH control for water densities above 0.17 g/cm 3 ( T 3 the pH control becomes progressively more difficult as water density decreases. The results also suggest that the pH control via LiOH (aq) addition at densities below 0.086 g/cm 3 ( T > 514 °C) is, arguably, impractical as it requires operation at high concentrations of LiOH (aq) .

ChemInform Abstract: Polyhedral Magnetite Nanocrystals with Multiple Facets: Facile Synthesis, Structural Modelling, Magnetic Properties and Application for High Capacity Lithium Storage.

AbstractPolyhedral Fe3O4 nanocrystals with multiple facets are hydrothermally synthesized from an aqueous solution of FeSO4, Fe(NO3)3, and LiOH (autoclave, 180 °C, 2 h).