Interaction of ammonium bicarbonate with lithium chloride solutions

The possibility of lithium carbonate precipitation in the interaction of a lithium chloride solution with ammonium bicarbonate is studied. It is shown that the theoretically possible degree of Li₂CO₃ precipitation cannot exceed approximately 80% and is determined by the solubility of the forming lithium carbonate in the NH₄Cl solution. In a real system, the degree of Li₂CO₃ precipitation is virtually temperature-independent within the range 20–90°C and does not exceed 70%. A closed process for mother liquor recovery at a significantly higher degree of Li₂CO₃ precipitation from the mother liquor is proposed.     

Influence of precursors of Li2O and MgO on surface and catalytic properties of Li‐promoted MgO in oxidative coupling of methane

The influence of the catalyst precursors (for Li₂O and MgO) used in the preparation of Li‐doped MgO (Li/Mg = 0.1) on its surface properties (viz basicity, CO₂ content and surface area) and activity/selectivity in the oxidative coupling of methane (OCM) process at 650–750 °C (CH₄/O₂ feed ratio = 3.0–8.0 and space velocity = 5140–20550 cm³ g⁻¹ h⁻¹) has been investigated. The surface and catalytic properties are found to be strongly affected by the precursor for Li₂O (viz lithium nitrate, lithium ethanoate and lithium carbonate) and MgO (viz magnesium nitrate, magnesium hydroxide prepared by different methods, magnesium carbonate, magnesium oxide and magnesium ethanoate). Among the Li–MgO (Li/MgO = 0.1) catalysts, the Li–MgO catalyst prepared using lithium carbonate and magnesium hydroxide (prepared by the precipitation from magnesium sulfate by ammonia solution) and lithium ethanoate and magnesium acetate shows high surface area and basicity, respectively. The catalysts prepared using lithium ethanoate and magnesium ethanoate, and lithium nitrate and magnesium nitrate have very high and almost no CO₂ contents, respectively. The catalysts prepared using lithium ethanoate or carbonate as precursor for Li₂O, and magnesium carbonate or ethanoate, as precursor for MgO, showed a good and comparable performance in the OCM process. The performance of the other catalysts was inferior. No direct relationship between the basicity of Li‐doped MgO or surface area and its catalytic activity/selectivity in the OCM process was, however, observed. © 2000 Society of Chemical Industry     

One-step conversion of sulfate lithium into high-purity lithium hydroxide crystals via bipolar membrane crystallization

To date, bipolar membrane electrodialysis (BMED) is being developed as a competitive technology for waste lithium-ion battery recovery. However, the purity and concentration of lithium hydroxide generated from a BMED plant could not meet the product criteria for ternary lithium batteries, thus requiring additional condensation, purification, evaporation, and crystallization procedures. Herein, bipolar membrane crystallization (BMC) was proposed for the one-step conversion of sulfate lithium into high-purity lithium hydroxide monohydrate crystals. By mediating a continuous saturated feedstock in the salt compartment, it is possible to convert Li₂SO₄ into 5+ mol/L LiOH at a current density higher than 500 A/m². Therefore, this unique design allows the production of 99.9% LiOH∙H₂O by taking the principle of water dissociation in the bipolar membrane and the simultaneous crystallization procedure. This proof-of-concept study proves the feasibility and competitiveness of the BMC for waste lithium recovery by abandoning the condensation and evaporation procedures.     

Lithium recovery from pretreated α-spodumene residue through acid leaching at ambient temperature

A novel alkaline hydrothermal approach for low-temperature conversion of α-spodumene into Li₂SiO₃ residue was proposed, providing a promising method for extracting lithium from α-spodumene as a pretreatment process. This work proposed a systematic investigation for extracting lithium from the residue by acid leaching and preparing lithium carbonate. The reaction feasibility between Li₂SiO₃ and acids (HCl and H₂SO₄) was first evaluated through thermodynamic calculation. Compared with the leaching effects of hydrochloric acid and sulphuric acid, sulphuric acid is the preferred leaching agent due to its higher extraction efficiency for lithium and lower acid consumption. Lithium extraction efficiency from the residue achieved up to 87.48% under the following optimized conditions: 0.75 mol/L H₂SO₄, 0.4 times the theoretical amount of acid, 10 min, 30°C, and 100 rpm. Based on the optimized conditions, the lithium-containing solution was concentrated through three consecutive cycles of leaching, which obtained a concentration of 17.78 g/L for lithium. The leaching solution was purified by CaO-Na₂CO₃, resulting in the removal rates of SiO₃²⁻, Mg²⁺, and Ca²⁺ of 84.22%, 95.51%, and 90.55%, respectively. Finally, the solution was precipitated with sodium carbonate to prepare Li₂CO₃. This paper facilitates the development of an economical process for efficient lithium extraction from spodumene at low temperatures.     

Direct preparation of battery-grade lithium carbonate via a nucleation–crystallization isolating process intensified by a micro-liquid film reactor

With the lithium-ion battery industry booming, the demand for battery-grade lithium carbonate is sharply increasing. However, it is difficult to simultaneously meet the requirements for the particle size and the purity of battery-grade lithium carbonate. Herein, the nucleation–crystallization isolating process (NCIP) is applied to prepare battery-grade lithium carbonate without any post-treatment procedure. The nucleation process is intensified by a micro-liquid film reactor (MLFR), where the feedstock solution is subject to intensive shear force and centrifugal force. The feedstock solutions are mixed rapidly and a large number of nuclei form instantly in the MLFR. After nucleation, the crystallization process is achieved in another reactor. A few new nuclei form in the crystallization process. The nucleation intensification in the MLFR is verified by computational fluid dynamics (CFD) simulations and experimental results. The particle size distribution is narrower and the impurity residue in the products is far lower than that prepared by a traditional precipitation method. The effects of nucleation and crystallization on the particle size distribution and purity were investigated. In the optimized operation parameters, the particle size distribution of the Li₂CO₃ product is D₁₀ = 2.856 μm, D₅₀ = 5.976 μm, and D₉₀ = 11.197 μm, and the purity is 99.73%, both of which meet the requirements of battery-grade Li₂CO₃. Moreover, the lithium recovery rate is increased to 88.21% compared to that prepared by a traditional precipitation method (79.0%). This work provides an alternative way for the preparation of high-purity chemicals by process intensification.     

Kinetics, energy characteristics, and intensification of crystallization processes in chemical precipitation of hardness ions

An analysis of the literature data on the solubility and kinetics of the chemical (reagent) precipitation of calcium carbonate and magnesium hydroxide is performed. The possible causes of the significant discrepancy in the available data are considered. The kinetics of the homogeneous and heterogeneous crystallization of calcium carbonate and magnesium hydroxide in reagent precipitation is studied using different methods. It is shown that the use of heterogeneous crystallization on seed particles pretreated in an ultrasonic field raises the rate of crystallization by an order of magnitude. The kinetics of nucleation is studied; the effect of supersaturation and temperature on the induction period in the homogeneous and heterogeneous nucleation of CaCO₃ and Mg(OH)₂ crystals is investigated. The energy characteristics of nucleation, namely, the interfacial tension (surface energy) and activation energy, are determined. The use of fine-dispersed particles activated by ultrasound makes it possible to considerably reduce the energy barrier for nucleation.     

Biomineralization of calcium carbonate by adding aspartic acid and lysozyme

Calcium carbonate is one of the most abundant materials present in nature. Crystal structures of CaCO₃ become three polymorphic modifications, namely calcite, aragonite and vaterite. Polymorphic modifications are mediated by adding aspartic acid (Asp) and lysozyme. Lysozyme, which is a major component of egg white proteins, has influenced the calcification of avian eggshells. The influence of Asp and lysozyme on the crystallization of CaCO₃ was investigated by adding these additives and calcium chloride solution into sodium carbonate solution in a crystallization vessel. CaCO₃ crystals were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectrometry (FT-IR). XRD was used to select the intensities and crystal structure of specific calcium carbonate. SEM was employed for the analysis of the morphology of the precipitation and particle size. Two kinds of crystals were identified by FT-IR spectrum. Hexagonal crystals of vaterite were affected by the Asp in the crystallization solution. However, rhombohedral crystals of calcite by lysozyme were formed without any sign of vaterite.     

Lithium Diffusion in Lithium Niobate Crystals with Different Initial Li2O Content at High Temperature

Lithium diffusion in lithium niobate crystals with different initial Li₂O content (C_initial) was investigated under Li‐rich environment at 1100°C. Lithium niobate crystals with widely varying diffusion‐limited Li₂O content profiles were prepared through the vapor transport equilibration (VTE) technique using congruent lithium niobate crystals with different C_initial, and the profiles were measured through Curie temperature by a thermal analyzer. A Boltzmann‐Matano analysis was employed to those profiles to estimate the Li⁺ diffusivity as a function of Li₂O content in lithium niobate crystals. A trigonometric function method was applied to those profiles to correlate diffusion time and Li₂O content. The results show that at the same composition of lithium niobate crystals after diffusing treatment, the less the C_initial, the larger the Li⁺ diffusivity. The relation between diffusion time and Li₂O content of the samples which have different C_initial and thickness was derived. Based upon the Boltzmann‐Matano result, diffusion time can be estimated easily from the relation. It is concluded that increasing C_initial contributes to shorten the diffusion time for preparing near‐stoichiometric lithium niobate crystals through the VTE technique, especially for thick crystal wafers.     

CaCO<Subscript>3</Subscript> crystallization with feeding of aspartic acid

Aspartic acid (Asp) was employed as the organic template in inducing the nucleation and growth of calcium carbonate. Crystallization experiments were carried out by the addition of Asp into the solution of sodium carbonate and calcium chloride. The effects of reaction time, dropping velocity of Asp and Na₂CO₃ solution were tested. The CaCO₃ crystals were analyzed by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and Fourier transform infrared spectrometry (FT-IR). Two kinds of crystals were identified by FT-IR spectrum. In the presence of Asp, formation of vaterite is induced in crystallization solution. Also, under the initial condition of an excess amount of Asp, vaterite morphology is the major one. Various morphologies of CaCO₃ are made by changing dropping velocity of added Asp and Na₂CO₃.     

Effect of liquid circulation in the draft-tube reactor on precipitation of calcium carbonate via carbonation

Precipitation of calcium carbonate was carried out in a draft-tube reactor by mechanical agitation of calcium hydroxide solution with carbon dioxide. The circulation of a reactive mixture was created by gas flow and a stirrer. It was observed that a higher circulation decreased the precipitation time and improved CO₂ consumption. A higher circulation velocity of liquid contributed to smaller calcium carbonate particles at the end of precipitation.     

Low Temperature Liquid State Synthesis of Lithium Zirconate and its Characteristics as a CO2 Sorbent

Abstract

In this study, a new preparation method providing greatly improved CO₂ sorption is introduced. Li₂ZrO₃ sorbent was prepared by low temperature co‐precipitation and compared in CO₂ sorption performance with a sorbent prepared by the conventional high temperature solid‐state reaction method. The two sorbents were characterized using scanning electron microscopy, X‐ray diffraction and thermo‐gravimetric analysis. The Li₂ZrO₃ powder prepared by the relatively simple co‐precipitation method showed significantly better performance than the one prepared by solid‐state reaction with respect to both kinetics and CO₂ sorption capacity. Extensive study of the powder prepared by co‐precipitation has been performed at various conditions.     

Recovery of Lithium from Seawater by Manganese Oxide Adsorbent

Abstract

Ion-sieve (microporous) type manganese oxide (HMnO) was prepared by acid treatment of lithium-introduced manganese oxide which was obtained from γ-type manganese oxide and lithium hydroxide. The HMnO showed high selectivity for lithium ions in seawater. The maximum lithium uptake by the HMnO from seawater reached 7.8 mg/g which corresponded to a lithium content of 1.7% as Li₂O. The adsorbed lithium could be easily eluted with 0.01 or 0.05 M hydrochloric acid solution. The adsorptive capacity for lithium ion scarcely changed during five repetitions of the adsorption-elution cycle. The column test was carried out by using granulated HMnO which was prepared with polyacrylic hydrazide as a binder.     

Electrochemical Recovery of Lithium Ions in the Aqueous Phase

Abstract

The electrochemical insertion of lithium ions into a Pt/λ-MnO₂ electrode was investigated in various metal chloride solutions. The Li⁺ insertion occurred effectively in LiCl solutions with higher concentration than 10 mmol/dm³, but it could hardly occur in a 0.1 mmol/dm³ LiCl solution. Alkaline earth metal ions showed a stronger inhibition effect against the Li⁺ insertion into the Pt/λ-MnO₂ electrode than alkali metal ions. However, since only Li⁺ ions were taken up from a mixed solution of lithium and alkaline earth metal chlorides, a high selectivity of the electrode for lithium ions was shown.

It was possible to recover lithium ions from geothermal water by this electrochemical method using the Pt/λ-MnO₂ electrode; the lithium uptake was 11 mg/g-MnO₂.     

Synthesis,kinetic study,and reaction mechanism of Li4SiO4 with CO2 in a slurry bubble column reactor

Abstract

This study was performed to investigate the synthesis, kinetic and reaction mechanism of Li₄SiO₄ with CO₂ in a slurry bubble column reactor. The Li₄SiO₄ powder sample was prepared via a solid-state reaction. The sample was characterized via X-ray diffraction (XRD) analysis and verified as a single phase. The median diameter of the sample was measured using the laser diffraction and scattering method as about 20?μm. The synthesized sample was suspended in binary molten carbonate of Li₂CO₃–K₂CO₃ having a molar ratio of 38:62. The experimental results show that Li₄SiO₄ in the slurry bubble column absorbed approximately a stoichiometric amount of CO₂. The kinetic study shows that the CO₂ reaction behavior on the Li₄SiO₄ surface was fitted to a double exponential model and the limiting step of the reaction was lithium diffusion. The mass transfer coefficient of CO₂ and rate constant of reaction with Li₄SiO₄ were studied to understand the overall absorption mechanism in the reactor. The resistance for the direct reaction of CO₂ on the Li₄SiO₄ was much smaller than the resistance for the mass transfer of CO₂ to the Li₄SiO₄. We can conclude that the direct contact of CO₂ with Li₄SiO₄ was the main path for the reaction.     

Effect of CO2 and melt decarbonation on the dimerization of methane in molten Li2CO3-Na2CO3-K2CO3 supported by LiAlO2 or Li2TiO3 at 750–850°C

The oxidative dimerization of methane was investigated at 750–850°C in Li₂CO₃-Na₂CO₃-K₂CO₃ immobilized within LiAlO₂ or Li₂TiO₃ supports. Catalytic performance was enhanced with moderate melt decarbonation (i.e. with molten phase/LiAlO₂ at 850°C: CH₄ conversion of 25% and C₂ yield of 12.5%), then dramatically fell with the precipitation of sodium and lithium oxide. The effect of the partial pressure of CO₂ was analyzed. As in the case of binary carbonate eutectics, catalytic activity of the ternary melt was correlated with the presence of peroxide species. This activity was more important when using LiA1O₂ support.     

Effects of sodium dodecyl benzenesulfonic acid (SDBS) on the morphology and the crystal phase of CaCO<Subscript>3</Subscript>

The effects of anionic surfactant on the morphology and crystallization of calcium carbonate precipitated from CaCl₂ and Na₂CO₃ were investigated. Although reaction temperature did not have an effect on the morphology of calcium carbonate, it did have an effect on the cluster size. The cluster size became bigger with high reaction temperature. With the addition of sodium dodecyl benzenesulfonic acid (SDBS), the morphology of precipitated calcium carbonate changed from cubic to porous spheres with over 98% of the crystal phase transformed from calcite to vaterite. The analysis of precipitates formed by the reaction of CaCl₂ solution (from limestone (CaO 50% content)) and Na₂CO₃ found that the morphology of precipitated calcium carbonate changed from cubic to spherical, and the crystal phase changed from calcite to over 94% vaterite with the addition of sodium dodecyl benzenesulfonic acid. These vaterite structures were solid spheres rather than hollow ones.     

Quantum Calculations of VX Ammonolysis and Hydrolysis Pathways via Hydrated Lithium Nitride

Recently, lithium nitride (Li₃N) has been proposed as a chemical warfare agent (CWA) neutralization reagent for its ability to produce nucleophilic ammonia molecules and hydroxide ions in aqueous solution. Quantum chemical calculations can provide insight into the Li₃N neutralization process that has been studied experimentally. Here, we calculate reaction-free energies associated with the Li₃N-based neutralization of the CWA VX using quantum chemical density functional theory and ab initio methods. We find that alkaline hydrolysis is more favorable to either ammonolysis or neutral hydrolysis for initial P-S and P-O bond cleavages. Reaction-free energies of subsequent reactions are calculated to determine the full reaction pathway. Notably, products predicted from favorable reactions have been identified in previous experiments.     

卤水结晶除杂工艺技术研究

介绍利用结晶器进行卤水除杂的一种工艺。旧工艺碳酸钠和氢氧化钠直接加入卤水除杂,容易产生碳酸钙和氢氧化镁胶体沉淀,难以过滤。采用结晶除杂工艺,减小钙镁的反应浓度,同时减小除杂剂离子的浓度,使生成杂质晶体的过饱和度得到控制。该工艺很好地控制杂质沉淀结晶的粒径,较好地解决盐泥的固液分离。实验验证了影响杂质结晶生长的因素。实验结果对比了卤水结晶除杂与传统除杂的盐泥分离效果,得到的结晶除杂盐泥抽滤速度比传统盐泥抽滤快30倍。     

Biological sequestration of carbon dioxide in geological formations

This paper presents the results of experimental investigation and analysis of challenges for utilizing enzyme bovine carbonic anhydrase for sequestration of CO₂ in saline formations. Several sets of controlled bench-top experiments were conducted, and results are presented in this paper, where effects of various parameters including pH, concentration of enzyme, and temperature on enhancing hydration and subsequent precipitation of CO₂ in the form of calcium carbonate were tested. A mathematical model describing the extent and rate of precipitation was developed upon analyzing the results of these tests. Subsequently, core flood tests were conducted where effect of enzyme on precipitation of CO₂ in Berea cores, and its impact on porosity and permeability of the porous media were investigated. These tests indicated that the pressure drop across cores was increased about 2-4 times, which is an indication of precipitation of CO₂ in the form of calcium carbonate in porous media. In addition to above tests, effect of timing and scheme of the injection on extent of CO₂ precipitation in porous media was tested. It was observed that co-injection of CO₂ and enzyme solution leads to higher pressure drop across the cores in tests reported here. Finally, the learning of above tests has been used to outline a series of potential challenges and propose solutions for effective utilization of enzyme bovine carbonic anhydrase for safe sequestration of CO₂ in saline formations.     

Lithium selective adsorption on low-dimensional titania nanoribbons

Mesoporous titania nanoribbons were synthesized via an optimized soft hydrothermal process and the derived titania ion-sieves with lithium selective adsorption property were accordingly prepared via a simple solid-phase reaction between Li₂CO₃ and TiO₂ nanomaterials followed by the acid treatment process to extract lithium from the Li₂TiO₃ ternary oxide precursors. First, mesoporous titania nanoribbons were prepared and the formation mechanism was discussed; second, the physical chemistry structure and texture were characterized by powder X-ray diffraction (XRD), (high-resolution) transmission electron microscopy (TEM/HRTEM), selected-area electron diffraction (SAED) and N₂ adsorption–desorption analysis (BET); third, the lithium selective adsorption properties were tested by the adsorption isotherm, adsorption kinetics measurement and demonstrated with the distribution coefficient of a series of alkaline and alkaline–earth metal ions.