LiOH Aqueous Solution Research Articles

Solid-phase nanoreactor based on calix[4]resorcinarene: Gel diffusion kinetics of ion exchange

A nanoreactor effect is found that consists in a considerable (two orders of magnitude) increase in the rate of ion exchange in sulfonated calixarene-containing polymers. The kinetics of ion exchange in network calixarene-containing polymers with sulfonic acid and phenolic ionogenic groups is studied. It is shown that the interaction of these polymers with aqueous solutions of LiCl, NaCl, AgNO3, LiOH, NaOH, and (CH3)4NOH is controlled by ion diffusion in the polymeric phase. An analytical dependence of the conversion on an interdiffusion coefficient and the time of ion exchange in bifunctional cation exchangers is derived using the spherical-layer model.

A facile method for the dechlorination of mono- and dichlorobiphenyls using Raney Ni–Al alloy in dilute aqueous solutions of alkali hydroxides or alkali metal carbonates

Raney Ni–Al alloy in a dilute aqueous alkaline solution of NaOH, KOH, CsOH, LiOH, or Ca(OH) 2 or of alkali metal carbonates such as Na 2CO 3, K 2CO 3 becomes a very powerful reducing agent and dechlorinates the polychlorobiphenyl(PCB) congeners mono- and dichlorobiphenyls effectively to afford biphenyl and/or phenylcyclohexane, respectively. The reactions are run under mild conditions without the use of organic solvents. The reductive dechlorination of dichlorobiphenyls with a Raney Ni–Al alloy under ultrasonication was investigated, also.

The kinetics of cation exchange in network calyxarene-containing polymers: the nanoreactor effect

The kinetics of cation exchange from aqueous solutions of electrolytes in network calyxarene-containing polymers with sulfo acid and phenol ionic groups was studied. It was shown that the interaction of the polymers with aqueous solutions of LiCl, NaCl, AgNO3, LiOH, NaOH, and (CH3)4NOH was controlled by ion diffusion in the polymer phase. The nanoreactor effect, that is, a significant increase in the ion exchange rate in sulfonated calyxarene-containing polymers, was observed. The spherical layer model was used to obtain an analytic dependence of conversion on the interdiffusion coefficient and ion exchange duration in bifunctional cationites.

Synthesis and Electrochemical Properties of Nanosized LixMnO2 as Cathode Materials for Lithium Batteries

Starting from and in LiOH aqueous solution, the nanosized nonstoichiometric with a rhombohedral structure were successfully synthesized via a low-temperature redox soft-chemistry route under the protection of liquid olefin at . Meanwhile, a partial doping by cations ( and ) or polyanions (, , and ) in nonstoichiometric was also performed. The microstructure and composition of the samples were characterized by X-ray diffraction, transmission electron microscopy, and inductively coupled plasma atom emission spectroscopy. It is shown that these samples with the rhombohedral structure have irregular shapes with a grain diameter between 20 and . The electrochemical performance of these samples as cathode materials was studied by galvanostatic method and electrochemical impedance spectroscopy. The large cation or polyanion doping in nanosized can improve the cycle stability and high-rate discharge capability.

Study on Influence of Tetragonal ZrO2 in Oxide Film on Corrosion Resistance of Zr-Sn-Nb Alloy

Abstract Zr-Sn-Nb alloy specimens treated in different ways were exposed to 0.01 mol/L LiOH aqueous solution at 350 °C, 16.8 MPa in autoclave. Spectroscopy Ellipsometry (S-E) was applied to investigate the effect of tetragonal ZrO2 (t-ZrO2) in oxide film on corrosion resistance of Zr-Sn-Nb alloy. It was found that the 580 °C/C. R/500 °C specimen corroded for 42 d and 190 d have more t-ZrO2 than other two specimens. But it is converse to the corrosion rate. It is suggested that the small amount of t-ZrO2 is a main factor to affect the corrosion resistance ability and the corrosion resistance is improved by the formation of t-ZrO2.

Preparation and characterization of LiAl xCo yNi 1− x− yO 2 particles

Lithium-aluminum-cobalt-nickel oxide (LiAl x Co y Ni 1− x− y O 2) particles, generally used as cathode of lithium battery, were prepared by chemical coprecipitation from an aqueous solution of LiOH, Al(NO 3) 3, Co(NO 3) 2 and Ni(NO 3) 2 with NH 4OH. XRD, SEM and FTIR were used to examine the effect of nickel content on the product. FTIR patterns showed that increase in nickel content decreased the absorption strength of the peak of spinel structure of the product, attributed to the occupation by nickel in the aluminum sites. Particle size and electrical properties of the lithium-aluminum-cobalt-nickel oxide (abbreviated as LACNO) particles were also determined.

Effect of heat treatment on the Nb distribution and corrosion resistance of Zr-Sn-Nb-Fe zirconium alloy

After being treated in different ways, Zr-Sn-Nb-Fe alloy specimens are exposed in 0.01mol/L LiOH aqueous solution at 350°C under 16.8 MPa. The examination of microstructures and second phase particles (SPPs) of these specimens was carried out by high-resolution transmission electron microscopy (HR-TEM). The specimens treated at 800°C before the final cold rolling have a better corrosion resistance than those treated at 680°C, and the specimens treated at 500°C, after the final cold rolling, have a better corrosion resistance than those treated at 560°C. TEM examination shows that the SPPs existing in the 800°C/500°C specimen, which has the best corrosion resistance, contains a lot of Nb element, which results in the reduction of the niobium content in the α-Zr solid solution.

Insights into the electrochemistry of layered double hydroxide containing cobalt and aluminum elements in lithium hydroxide aqueous solution

The electrochemical capacitive behavior of layered double hydroxide containing cobalt and aluminum (Co–Al LDH), synthesized by a “memory effect” route, was in detail evaluated by cyclic voltammetry (CV) and chronopotentiometry in 1 M LiOH aqueous electrolyte. A specific capacitance of 187 F g −1 was obtained even after 1000 cycles at a current of 2 A g −1. Moreover, it was found that Co–Al LDH undergoes two independent electrode processes in LiOH aqueous solution, involving the simultaneous intercalation of an ion-pair, i.e. lithium cation and hydroxyl group, which is different from the mechanisms in NaOH and KOH aqueous solutions. The possible reason is thought to be the selective intercalation into Co–Al LDH for alkali metal ions due to their respective ionic radius. Only the cation with appropriate size is suited for inserting into [Co(OH) 6] or [Al(OH) 6] octahedral vacancies.

Electrochemical Properties of Lithium Titanate Synthesized by Reassembly of Nanosheets

The electrochemical properties of titanate nanosheets and layer-structured lithium titanate obtained by restacking of titanate nanosheets were investigated in comparison with those of layer-structured lithium titanate obtained by ion-exchange. Restacked lithium titanate was synthesized by reassembling titanate nanosheets with LiOH aqueous solution. The nanosheets were 50-200 nm wide and 1.7 nm thick. The crystal structure inside the nanosheets was the same as that the of parent material. The oxidation current peaks observed in cyclic voltammograms of titanate nanosheets and restacked material were 1.6 V (Li/Li+), which was lower than that of ion-exchanged material by 0.3 V. The discharge capacity of restacked material was 96 mAh g-1, indicating that 32% of the titanium ions were reduced.

Novel High-Rate Lithium Intercalation Electrode Materials Prepared by LiOH Solution Treatment of TiO<sub>2</sub>/Carbon Composites

Anatase-type TiO2-based oxide gel /carbon composites were treated chemically with LiOH aqueous solution at 60 °C. The crystalline phase of treated powder was examined by powder x-ray diffraction using CuKα radiation. The main diffraction peaks may be detected as belonging to cubic LiTiO2. High-rate lithium intercalation properties of the samples were estimated in nonaqueous electrolyte including lithium ions. The composite electrodes exhibited high coulombic efficiency over 90% at first cycle and high capacities over 200 mAh g-1 after 200 cycle at large charge-discharge current density of 5.0 mA cm-2 (3.7 A g-1). The composite materials are one of the promising candidates as electrode materials for energy storage devices, such as hybrid capacitor, that require high-power operations.

A superior corrosion behavior of Zircaloy-4 in lithiated water at 360 °C/18.6 MPa by β-quenching

To further understand the mechanism on the heat-treatment effect on corrosion behavior of Zircaloy-4, β-quenched and recrystallized specimens are corroded in an autoclave with 0.01 M LiOH aqueous solution at 360 °C/18.6 MPa. Results show that the β-quenched specimen possesses excellent corrosion resistance, the weight gain of which is consistently comparable to that of ZIRLO and N18 alloys during 529 days exposure, while the recrystallized specimen exhibits accelerated corrosion rate after 100 days exposure. The increase of the supersaturated solid solution contents of Fe and Cr in α-Zr matrix is responsible for the improvement of corrosion resistance by β-quenching treatment. The fracture surface and inner surface morphology of oxide films indicates that β-quenching treatment significantly slow down the development of pores to cracks in oxide films and reduces the uneven growing tendency of the oxide, which is related to the corrosion behavior.

Splitting tendency of cellulosic fibers. Part 3: splitting tendency of viscose and modal fibers

The splitting tendency of viscose and modal fibers in aqueous alkali solutions of LiOH, NaOH, KOH and TMAH was investigated. The viscose fibers splitted up to 5–7 fibrils, whereas modal fibers splitted up to 2–4 fibrils depending on alkali type and concentration. The fibrillar structure of lyocell enables it to split more (15–20 fibrils) than viscose and modal fibers. Splitting occurs where internal stress of fiber is high due to different alkali or void distribution inside fiber. The splitting test couldn’t be achieved for viscose and modal fibers between 1 and 5 M concentration of NaOH and TMAH solutions due to breakage of fibers during test. Above 5 M concentration, no split can be observed due to even distribution of alkali inside fiber.

Probing water dynamics with OH −

Isotropic Raman spectra of aqueous solutions of LiOH, NaOH and KOH at concentrations ranging from high dilution to saturation have been measured and the frequency and width of the OH − stretching band have been analyzed. The dependence of the bandwidth on solute concentration suggests that the OH − vibration undergoes a transition from fast to slow modulation regimes as the solvent concentration decreases below the value of ∼20 water molecules per solute molecule. A correlation between this finding and structural modifications of the H-bond network of the solvent at similar concentrations is envisaged.

In-Situ Grafting of Hyperbranched Poly(ether ketone)s onto Multiwalled Carbon Nanotubes via the A3 + B2 Approach

Trimesic acid and phenyl ether were in-situ polymerized as A3 and B2 monomers, respectively, in the presence of a fixed amount (10 wt %) of multiwalled carbon nanotube (MWNT) to afford hyperbranched poly(ether ketone)s (PEK's)/MWNT nanocomposites. The feed ratios of A3 and B2 monomers vary from 3:2 to 1:2 in the A3 + B2 polycondensations. The polymerization was carried out in a mildly acidic medium, i.e., poly(phosphoric acid) or PPA, with an optimized amount of phosphorus pentoxide (P2O5) added. The overall evidence based on the data of elemental analysis (EA), thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) implicates that hyperbranched PEK's were attached to the surface of MWNT to form hyperbranched PEK-g-MWNT nanocomposites. Furthermore, MWNT remained structurally intact under the polymerization and workup conditions. Evidently driven by the molecular architecture of globular hyperbranched polymers, the morphology of the nanocomposites resembles “mushroom-like clusters on MWNT stalks”. The hyperbranched PEK-g-MWNT nanocomposites were soluble in polar aprotic solvents stemming from numerous carboxylic acids on their surfaces. When some of samples were dispersed in 1 M LiOH aqueous solutions, they formed very stable suspensions. The resulting lithiated nanocomposites are being investigated in the applications such as ion conductivity and energy capacitance.

A study of lithium insertion into MnO2 containing TiS2 additive a battery material in aqueous LiOH solution

The electrochemical behavior and surface characterization of manganese dioxide (MnO2) containing titanium disulphide (TiS2) as a cathode in aqueous lithium hydroxide (LiOH) electrolyte battery have been investigated. The electrode reaction of MnO2 in this electrolyte is shown to be lithium insertion rather than the usual protonation. MnO2 shows acceptable rechargeability as the battery cathode. The influence of TiS2 (1, 3 and 5 wt%) additive on the performance of MnO2 as a cathode has been determined. The products formed on reduction of the cathode material have been characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), fourier transform infrared spectroscopy (IR) and transmission electron microscopy (TEM). It is found that the presence of TiS2 to ≤3 wt% improves the discharge capacity of MnO2. However, increasing the additive content above this amount causes a decrease in its discharge capacity.

Mn-smectites: Hydrothermal synthesis and characterization

Three varieties of Mn-smectites (hectorite, stevensite and saponite) were hydrothermally synthesized for the first time using silicic acid, MnCO 3 and Al(NO 3) 3·9H 2O mixed with aqueous solutions of NaOH or LiOH. The staring materials were treated in the temperature range of 125–200 °C for 72–168 h and the best synthesis temperature was found to be 175 °C. A lower Mn/Si molar composition than stoichiometric ideal composition was found to be most effective for the formation of almost pure and crystalline phases, apparently high Si is needed for their stability. Powder X-ray diffraction (XRD) and thermal properties of the Mn-hectorite product have been investigated and compared to those of Zn-hectorite, which was previously synthesized by us. Manganese hectorite showed slightly larger expandability upon glycerol treatment and lower dehydroxylation temperature in the range of 300–450 °C by DTA and TG as compared to Zn-hectorite.

Microwave assisted hydrothermal conversion of Ba-exchanged zeolite A into metastable paracelsian

A microwave assisted crystallization of paracelsian, a metastable phase for which no synthetic occurrence is at present reported, was obtained. A sample of thoroughly Ba-exchanged zeolite A was prepared and reacted in alkaline media and hydrothermal conditions under the action of microwaves (frequency 2.45 GHz, irradiation power 1000 W). The alkaline environment was created by using aqueous solutions of LiOH and tetraethylammonium hydroxide. Treatment temperature, reaction time and weight solid/liquid ratio ranged between 150 and 230 °C, 40 and 120 min, 1/5 and 1/40, respectively. The pressure was autogeneous. The action of microwaves appears to strongly enhance the ability of hydrothermal systems to produce highly metastable phases, an important observation.

Hydrothermal phase formation of orthorhombic LiMnO 2 and its derivatives as lithium intercalation compounds

Different from a conventional solid state reaction, a hydrothermal reaction mechanism is very difficult to illuminate and sometimes it remains undisclosed. Making an attempt to understand the hydrothermal phase formation process of o-LiMnO 2 obtained between the reaction of spinel type Mn 3O 4 precursor and LiOH aqueous solution, the possible reaction route was postulated and experimentally testified. Firstly, the selective dissolution of Mn 2+ from the tetrahedral site of [Mn II] tet 4 a [Mn III 2] oct 8 d O 4, which is considered as to be an ionic exchange reaction with Li +, and an additional Li + intercalation into the host structure of precursor would give rise to the formation of meta-stable Li 2Mn 2O 4 ([Li I] tet 4 a [Li I] oct 8 c [Mn III 2] oct 8 d O 4). Secondly, the phase would be simultaneously transformed to thermodynamically stable o-LiMnO 2 phase under hydrothermal state during hydrothermal reaction. Through the above reaction process, the solid solution range of o-LiCo x Mn 1− x O 2 was as large as x ≤ 0.14, and that of o-LiFe x Mn 1− x O 2 was x ≤ 0.05. Co doped o-LiMnO 2 has higher capacity and good cyclability upon cycling, being substantially more stable to cycle than the unsubstituted and Fe doped materials.

ZnO single crystals: Synthesis and characterization

Zinc oxide crystals grown in a single basic mineralizer in hydrothermal autoclaves are of poor quality. The crystals are transparent, pale green or pale yellow in color depending on different technical growth conditions. The quality of crystals under different conditions was observed by X-ray rocking curves measurement. The use of ultra-pure nutrient improves their perfection and purity. Zinc oxide bulks that were grown by the hydrothermal method in a mixture of KOH and LiOH aqueous solutions are of good quality.

Effect of heat treatment on the microstructure and corrosion resistance of a Zr–Sn–Nb–Fe–Cr alloy

Zr–Sn–Nb–Fe–Cr zirconium alloy specimens treated in different ways were exposed to 0.01M LiOH aqueous solution at 350°C, 16.8MPa. The microstructures of these specimens were investigated by transmission electron microscopy (TEM). It is found that the specimen treated by 800°C/500°C had best corrosion resistance among all the specimens. TEM analysis of this specimen showed that, in addition to Zr(Fe,Cr)2, there existed Zr–Nb–Fe type precipitates containing much more Nb element, which reduced niobium content in αZr solid solution and, therefore, resulted in an improvement in the corrosion resistance of Zr–Sn–Nb–Fe–Cr zirconium alloy.