LiAl-layered Double Hydroxides Research Articles

Reconstruction of MgAl-layered double hydroxides to LiAl-layered double hydroxides for scalable lithium extraction from salt lake brine

MgAl-layered double hydroxides (MgAl-LDHs) attract interest for lithium extraction due to their wide availability, high stability, and environmental friendliness. LiAl-layered double hydroxides (LiAl-LDHs) can be obtained by lithiation of MgAl-LDHs, yielding the facile preparation of adsorbents with high selectivity. Herein we synthesized porous MgAl-LDHs by a sol-gel method. MgAl-LDHs can be converted into LiAl-LDHs via dissolution and recrystallization process in LiOH solution. The structure of MgAl-LDHs dissolves, and Mg2+ exchange with Li+ in the solution to generate LiAl-LDHs. Mg2+ enter the solution. MgAl-LDHs and LiAl-LDHs were characterized using X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), N2 adsorption-desorption isotherms and X-ray photoelectron spectroscopy (XPS). The granulation of MgAl-LDHs and LiAl-LDHs was facilitated by chemical/physical cross-linking of sodium alginate using CaCl2 solutions. The performance of lithium extraction was investigated using synthetic brines, and real salt lake brines. The results showed that MgAl-LDHs and LiAl-LDHs adsorbents registered an adsorption capacity of 9.7 and 6.4 mg/g, respectively, at pH = 6 in 300 mg/L of Li+ solutions. The kinetic analysis revealed that granulated MgAl-LDHs and LiAl-LDHs exhibited pseudo-second-order adsorption behavior attributed to the redox behavior. In the brine of East Taigener Salt Lake, the granulated MgAl-LDHs and LiAl-LDHs achieved an adsorption capacity of 15.5 and 9.1 mg/g, respectively. The granulated LiAl-LDHs and MgAl-LDHs are promising for scalable lithium extraction from salt-lake brines.

Influence of Li+/Al3+ on the corrosion behavior of Li-Al layered double hydroxides (LDHs) film on LA51 magnesium alloys

A hierarchical superhydrophobic Al-Li layered double hydroxide (LDH) films with different Li + /Al 3+ molar ratios of 1:1, 1:2, 2:1, pH value of 11.5 and reaction temperature of 125 °C, have been fabricated on the surface of Mg-5Li-1Al (LA51) alloys by hydrothermal method following the characteristics of controllable cation structure and exchangeable anion between layers. The properties of the films were investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). XRD and SEM results indicate that the Al-Li LDH films are successfully prepared on LA51 alloys. The contact angle (CA) was measured to be about 100.7°, indicating that the surface wettability of the film converted from hydrophilic to hydrophobic by surface modification. The corrosion resistance of Al-Li LDH films was evaluated by Tafel polarization curve and electrochemical impedance spectroscopy (EIS). Surprisingly, Tafel polarization curve and EIS test reveal that the Al-Li LDH films prepared at the molar ratio of Li + /Al 3+ 1:2, pH 11.5 and temperature 125 °C have better corrosion resistance in 0.1 M NaCl neutral solution. In addition, the formation mechanism and corrosion mechanism of the films on the surface of LA51 alloy are also proposed. It provides innovative synthetic materials and novel design ideas for the preparation of high-efficiency anti-corrosion coatings on LA51 alloys, whose application can be extended in industrial fields.

Lithium adsorption properties of porous LiAl-layered double hydroxides synthesized using surfactants

Porous LiAl-layered double hydroxides (LiAl-LDHs) of [Li2Al4(OH)12](CO3)·4H2O were hydrothermally synthesized in one-pot by mixing LiCl, AlCl3, urea, and one surfactant each (sodium dodecyl sulfate (SDS), octadecyl amine (OA), and sodium lauryl sulfonate (SLS)) as soft templates. The LiAl-LDHs were granulated by crosslinked sodium alginate. The LiAl-LDHs were characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and porosity. Special attention was focused on the rise of Li+ adsorption capacity based on the porous morphology in synthetic and real salt lake brine. The adsorption capacity of granulated LiAl-LDHs-SLS reaches 8.48 mg/g in a solution containing 300 mg/L of Li+ at pH = 7 and 11.8 mg/g from Da Qaidam brine with 1.0 g/L of Li+. Lithium adsorption followed the Langmuir isotherm and pseudo-second-order kinetics. Temperature, solution pH, and other electrolytes had a minor effect on the adsorption performance of porous LiAl-LDHs. The structure of surfactants had a significant influence on the porosity of synthesized LiAl-LDHs, and thus on the adsorption capacity.

Corrosion Resistance of Li-Al LDHs Film Modified by Methionine for 6063 Al Alloy in 3.5 wt.% NaCl Solution

Methionine (Met) was introduced to modify the Li-Al layered double hydroxides (LDHs) film prepared on 6063 aluminum alloy by in situ method for the first time. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Scanning electron microscopy, and X-ray diffraction confirmed the successful insertion of Met into LDHs film and revealed that the introduction of Met could make the LDHs film much denser. Electrochemical tests illustrated that the corrosion rate of the Met modified LDHs film was reduced by more than an order of magnitude compared with the bare Al alloy. Moreover, the corrosion rate of the modified LDHs film after immersion in 3.5 wt.% NaCl solution for 21 days was almost the same as that without immersion, which indicates that the modified film has good corrosion durability. The corrosion resistance of the scratched modified film could recover to the level without a scratch on the 14th day based on the scratch test results, meaning the modified film has a good self-healing property. Finally, the anti-corrosion mechanism of the Met was proved by molecular dynamic simulations and found that the enhanced corrosion resistance may be attributed to the addition of Met that slowed the diffusion of the corrosive medium Cl− and water molecules.

Synthesis and Lithium Adsorption of Flower-Like Lial-Layered Double Hydroxides Adsorbents

Synthesis and Lithium Adsorption of Flower-Like Lial-Layered Double Hydroxides Adsorbents

A Genetic Algorithmic Approach to Determine the Structure of Li-Al Layered Double Hydroxides.

Layered double hydroxides (LDH) demonstrate significant potential across a range of applications, including as catalysts, delivery vehicles for pharmaceuticals, environmental remediation, and supercapacitors. Explaining the mechanism of LDH action at the atomic scale in these and other applications is challenging, however, due to the difficulty in precisely defining the bulk and surface structure and chemical compositions. Here, we focus on the determination of the structure of lithium-aluminum (Li-Al) LDH, which has shown promise in the catalytic depolymerization of lignin, both directly as the catalyst and as a support for gold nanoparticles. While the relative positions of the Li and Al metals are generally well resolved by X-ray crystallography, it is the structures of the anionic layers, consisting of water and carbonate, that are less well established. Combinatorial analyses of all possible positions and rotations of the water and carbonate in the three-layered Li-AL LDH polytope reveals that the phase space is much too large to examine in any reasonable time frame in a one-by-one structure exploration. To overcome this limitation, we develop and deploy a genetic algorithm (GA) wherein fitness is determined by matching a calculated X-ray diffraction (XRD) pattern for a given structure to the known experimental XRD pattern. The GA approach results in structures of high fitness that portend the bulk Li-Al LDH structure. Importantly, the GA approach offers the potential to determine the structures of other LDH, and more generally layered materials, which are generally difficult to describe given the large chemical and structural space to be explored.

Properties of calcium sulfoaluminate cement-based grouting materials with LiAl-layered double hydroxides slurries

In this study, LiAl-layered double hydroxides Lithium aluminum hydrotalcite (LiAl-LDH) with different specific surface area were prepared by the separate nucleation and aging steps (SNAS) method and then were employed to prepare calcium sulfoaluminate cement-based grouting material (CBGM) paste. The influence of LiAl-LDH slurries on fresh and hardened properties of the CBGM paste was investigated in terms of fluidity, stability, setting time, and compressive strength. Additionally, the hydration process and hydration products of the CBGM paste were characterized by hydration heat, X-ray diffraction, differential thermal analysis–thermogravimetry, and Fourier transform infrared analyses. The acquired results illustrated that LiAl-LDH with larger specific surface area led to a faster hydration rate at early age, a lower fluidity, a shorter setting time, and a higher stability. Furthermore, due to the crystal nucleation effect, the addition of LiAl-LDH slurries did not cause a new phase to form but changed the morphology and increased the amount of hydration products, yielding higher compressive strength.

Properties of sulfoaluminate cement-based grouting materials modified with LiAl-layered double hydroxides in the presence of PCE superplasticizer

Sulfoaluminate (CSA) cement-based grouting materials (CBGM), due to their fast hydration rate and high early strength, can be used in repair and reinforcement projects. To obtain a high workability, CBGM has often been modified by a polycarboxylate ether (PCE) superplasticizer with a high water to binder ratio (>0.5), which results in a poor compressive strength. Nano LiAl-LDH has been reported to have excellent properties for improving the mechanical behavior of sulfoaluminate (CSA) cement clinkers. In addition to the physicochemical characteristics of the nanomaterials, the admixtures used in CBGM paste can also affect the properties of the nanomaterials. In this paper, the effect of the PCE superplasticizer concentration on the properties of CBGM modified with LiAl-LDH was investigated, and a possible reason is provided. The results show that low PCE superplasticizer concentrations (0.9 wt% and 1.15 wt%) increased and high PCE superplasticizer concentrations (1.38 wt%, 1.76 wt% and 2.13 wt%) decreased the compressive strength of a CBGM paste modified with LiAl-LDH in comparison with that of the control paste. The PCE superplasticizer did not intercalate into the interlayers of the LiAl-LDH, and the interaction between the PCE superplasticizer and LiAl-LDH was limited to surface adsorption. A small quantity of lithium ions was released from the precipitation-dissolution equilibrium of LiAl-LDH in the slurry. Lithium atoms can enter the vacant octahedral sites of montmorillonite, which is one component of the CBGM, via isomorphous substitution, and the interaction decreased the adsorption quantity of the PCE superplasticizer on the bentonite surface, resulting in the high fluidity of the CBGM paste in the presence of a high PCE superplasticizer concentration.

Effect of LiAl-layered double hydroxides on hydration of calcium sulfoaluminate cement at low temperature

To reveal the effect of LiAl-layered double hydroxides (LiAl-LDHs) on hydration of calcium sulfoaluminate cement at low temperature, pastes with and without it were prepared and cured at temperature −10 °C. Setting times and compressive strength of pastes were measured. Mercury intrusion porosimetry (MIP) was used to reveal the evolution of pastes microstructure. X-ray diffraction (XRD), Thermogravimetric analysis (TG) and 27Al nuclear magnetic resonance (NMR) were adopted to qualify and quantify the hydration productions. The results show that, LiAl-LDHs is an effective hydration accelerator of CSA cement at low temperature. Initial and final setting times are reduced linearly with the increase of LiAl-LDHs content. However, peak of compressive strength emerges at the content of 1.0%. At this content, modified paste achieves 5.5 times compressive strength of plain one at 1 day and 1.4 times at 28 days. In presence of LiAl-LDHs, more ettringite crystallizes in modified pastes up to 28 days. Denser pastes obtained thereby.

Determination of boundary conditions for highly efficient separation of magnesium and lithium from salt lake brine by reaction-coupled separation technology

The high Mg/Li ratio in salt lake brine in China remains a challenge for the efficient separation of Mg and Li and the Li extraction. A reaction-coupled separation technology we proposed has been successfully applied to the highly efficient separation of Mg and Li from the brine. In this work, we conducted intensive investigations both experimentally and theoretically on the boundary conditions of Mg/Li separation from the brine in association with the initial Mg/Al ratio and Mg/Li ratio. We analyzed the relationship between the composition and the formation of precipitates by changing the Mg/Al molar ratio and the Mg/Li mass ratio in feedstock solution to determine the boundary conditions. The experimental results show that the Mg/Al molar ratio in the initial solution has a great influence on the separation of magnesium and lithium. It is evident that lithium enters the solid as a LiAl-layered double hydroxides (LiAl-LDHs) phase when the Mg/Al molar ratio is less than 2. It has also been found that the precipitate is independent of the Mg/Li mass ratio. From the theoretical results, it has been determined that an increase in the number of Li+ clusters results in a decrease of the binding energy in the same system. Al3+ prefers to combine with Mg2+ to form MgAl-LDH clusters. However, when the Mg/Al ratio is lower than 2:1, Li+ can form a cluster of LiAl-LDH layer. It can also be seen that different Li+ numbers do not change the formation of clusters. Good agreement was found between the theoretical simulation results and the experimental data. This work provides a key criterion for the efficient separation of magnesium and lithium from the brine by a reaction-coupled separation technology.

Highly Efficient Lithium Recovery from Pre-Synthesized Chlorine-Ion-Intercalated LiAl-Layered Double Hydroxides via a Mild Solution Chemistry Process.

Lithium extraction from salt lake brine is critical for satisfying the increasing demand of a variety of lithium products. We report lithium recovery from pre-synthesized LiAl-layered double hydroxides (LDHs) via a mild solution reaction. Lithium ions were released from solid LiAl-LDHs to obtain a lithium-bearing solution. The LiAl-LDHs phase was gradually transformed into a predominantly Al(OH)3 phase with lithium recovery to the aqueous solution. The lithium recovery percentage and the concentration of the lithium-bearing solution were dependent on the crystallinity of LiAl-LDHs, the initial concentration of the LiAl-LDHs-1 slurry, the reaction temperature, and the reaction time. Under optimized conditions, the lithium recovery reached 86.2% and the Li+ concentration in the filtrate is 141.6 mg/L. Interestingly, no aluminum ions were detected in the filtrate after solid–liquid separation with high crystallinity LiAl-LDHs, which indicated the complete separation of lithium and aluminum in the liquid and solid phases, respectively. The 27Al NMR spectra of the solid products indicate that lithium recovery from the lattice vacancies of LiAl-LDHs affects the AlO6 coordination in an octahedral configuration of the ordered Al(OH)3 phase. The XPS O 1s spectra show that the Oad peak intensity increased and the OL peak intensity decreased with the increasing lithium recovery, which indicated that the Al-OH bond was gradually formed and the metal–oxygen–metal bond was broken.

Enhanced corrosion protection property of Li-Al layered double hydroxides (LDHs) film modified by 2-guanidinosuccinic acid with excellent self-repairing and self-antibacterial properties

The long-lasting chrome-free, corrosion-resistant surface treatment of aluminum is of crucial importance. In our work, we prepared an intrinsic self-repairing and self-antibacterial film of single step in-situ grown inorganic lithium (Li), aluminum (Al)-containing layered double hydroxides film modified by 2-guanidinosuccinic acid (denoted as GLDHs) on the surface of 6 N01-T5 Al alloy by a facile method with enhanced corrosion protection performance. A series of electrochemical tests and neutral salt tests (NSS) showed that the corrosion resistance performance of GLDHs was significantly improved as compared with blank LiAl-LDH film. Interestingly, an artificial defect in the GLDHs film exhibited remarkable performances of self-repairing. After immersion in 3.5 wt% NaCl solution for certain time, new LiAl-LDH film at the Al alloy surface were formed, which was characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), inductive coupled plasma emission spectrometer (ICP), elemental analyzer, polarization curves, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). A self-repairing mechanism was proposed and discussed. Furthermore, GLDHs also exhibited excellent self-antibacterial activity toward Escherichia coli and Bacillus subtilis. The high self-antibacterial performance of GLDHs film could attribute to the modified 2-guanidinosuccinic acid. Our full demonstration of the multifunctional GLDHs film is considerably beneficial to the researchers to further understand its potential for the practical application in the field of corrosion protection of aluminum and aluminum alloy.

Highly efficient extraction of lithium from salt lake brine by LiAl-layered double hydroxides as lithium-ion-selective capturing material

Abstract The extraction of lithium from salt lake brine in the Chinese Qaidam Basin is challenging due to its high Mg/Li and Na/Li ratios. Herein, we utilized a reaction-coupled separation technology to separate sodium and lithium ions from a high Na/Li ratio brine (Na/Li = 48.7, w/w) and extracted lithium with LiAl-layered double hydroxides (LiAl-LDHs). The LiAl-LDHs act as lithium-ion-selective capturing materials from multi-cation brines. That is, the lithium ions selectively enter the solid phase to form LiAl-LDHs, and the sodium ions are still retained in the liquid phase. This is because the lithium ions can be incorporated into the structural vacancies of LiAl-LDHs, whereas the sodium ions cannot. The effects of reaction conditions on lithium loss and separation efficiency were investigated at both the nucleation and the crystallization stage, e.g., the nucleation rotating speed, the Li/Al molar ratio, the crystallization temperature and time, and co-existing cations. The lithium loss is as low as 3.93% under optimal separation conditions. The sodium ions remained in the solution. Consequently, an excellent Na/Li separation efficiency was achieved by this reaction-coupled separation technology. These findings confirm that LiAl-LDHs play a critical function in selectively capturing lithium ions from brines with a high Na/Li ratio, which is useful for the extraction of lithium ions from the abundant salt lake brine resources in China.

Enhanced Defluoridation Using Novel Millisphere Nanocomposite of La-Doped Li-Al Layered Double Hydroxides Supported by Polymeric Anion Exchanger

A novel nanocomposite bead LaLiAl-LDH@201 was fabricated by doping a small amount of La into nanocrystalline Li/Al layered double hydroxides (LDHs) pre-confined inside polystyrene anion exchanger D201 (LiAl-LDH@201). A systematic characterisation of the resultant LaLiAl-LDH@201 (XRD, SEM-EDS, TEM-EDS, and XPS) evidenced the successful incorporation of La into the Li/Al LDHs, with their interlayer distance expanded to allow more exchangeable sites for fluoride uptake. The resultant LaLiAl-LDH@201 showed high and stable defluoridation performance over a wide range of pH from 4 to 9. The superior uptake capacity and affinity for fluoride of LaLiAl-LDH@201 over LiAl-LDH@201 were driven by both the increased anion exchange capacity of the embedded LDHs and the specific La-F interaction evidenced via XPS and TEM-EDS characterisation. Fixed-bed column test confirmed that the working capacity of LaLiAl-LDH@201 for defluoridation of authentic fluoride-rich groundwater was nearly twice that of LiAl-LDH@201. The fluoride-loaded LaLiAl-LDH@201 could be conveniently regenerated in situ by using NaOH + NaCl binary solution, achieving desorption efficiency above 98%. Moreover, negligible capacity loss, La leaching, or structure alteration was observed after five adsorption-regeneration cycles, indicating the high stability of LaLiAl-LDH@201. Therefore, the novel millisphere nanocomposite LaLiAl-LDH@201 was promising for efficient defluoridation from water and wastewater.

Mechanochemically synthesized LiAlOx catalyst for aqueous aldol condensation of furfural with acetone

AbstractIn the present study, the mechanochemical method is proposed for synthesis of LiAl-layered double hydroxides (LDHs). This method is eco-friendly and allows obtaining LiAl-LDH under relatively mild conditions (centripetal acceleration of milling bodies 300 m s-2) and in a short period of time (15 minutes). The structures of as-prepared LiAl-LDH, LiAl-mixed oxide (calcined LDH) and “activated” LiAl-LDH obtained after rehydration of the corresponding mixed oxide were confirmed by X-ray diffraction. The basicity of LiAlOx was measured by temperature-programmed desorption of CO2 and double isotherm technique. According to data obtained, LiAl-mixed oxide has a significant higher carbon dioxide adsorption capacity compared to MgAlmixed oxides prepared by conventional co-precipitation method. This indicates a large amount of basic surface sites with different strength (strong, medium and weak) for Li-containing systems. The formation of “activated” LiAl-LDH having Bronsted basic sites (OH groups in the interlayer space) provides an increased catalytic activity of LiAlOx in the reaction of aqueous-phase aldol condensation between furfural and acetone.

Effects of LiAl-layered double hydroxides on early hydration of calcium sulphoaluminate cement paste

As a 3D micro-nano material, layered double hydroxides have been widely used in many fields, especially for reinforced composite materials. In this paper, LiAl-LDHs was obtained by a hydrothermal method. In order to investigate the effects of LiAl-LDHs on the early hydration of calcium sulphoaluminate (CSA) cement paste, compressive strength, setting time and hydration heat were tested while X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scaning electron microscopy (SEM) and differential scanning calorimetry (DSC) analysis were employed. The results indicated that LiAl-LDHs could significantly improve the early compressive strength and shorten the setting time of calcium sulphoaluminate cement paste with 3wt% concentration. Besides, the hydration exothermic rate within 5 h was accelerated with increasing LiAl-LDHs content. Moreover, the addition of LiAl-LDHs did not result in the formation of a new phase, but increased the quantity of hydration products providing higher compressive strength, shorter setting time and denser microstructure.

Influence of LiAl-layered double hydroxides with 3D micro-nano structures on the properties of calcium sulphoaluminate cement clinker

The effect of LiAl-layered double hydroxides (LiAl-LDHs) with 3D micro-nano structures on the early properties and hydration process of calcium sulphoaluminate cement (CSAC) clinker was investigated. Three LiAl layered double hydroxides (LiAl-LDHs) with different particle size were prepared through a facile solvothermal method. CSAC clinker incorporating LiAl-LDHs with constant water to cement radio were made and tested. The results indicate that a higher content of LiAl-LDHs resulted in a faster hydration rate, a shorter setting time and a higher early compressive strength. Besides, with the decrease of the particle size of LiAl-LDHs, the hydration rate was accelerated with corresponding increase in compressive strength. However, the influence of particle size of LiAl-LDHs on the setting time of CSAC clinker is not significant. Moreover, the addition of LiAl-LDHs did not result in a new phase formed, but increased the quantity of hydration products providing higher compressive strength and shorter setting time.

Mechano‐Hydrothermal Synthesis of Tetraborate Pillared Li–Al Layered Double Hydroxides

Tetraborate pillared Li–Al layered double hydroxide was synthesized for the first time by a mechano‐hydrothermal process in which gibbsite (Al(OH)3) sample was first activated by a ball milling, followed by hydrothermal treatment with Li2B4O7 in water at 95°C. Activation of gibbsite Al(OH)3 induced by mechanochemical process was essential for the formation of thin disk‐like Li–Al LDH intercalated with borate anion. When in excess the activated Al(OH)3 was transformed into bayerite phase during the hydrothermal process.

Optimizing the Conditions of Mechanochemical Synthesis of LiAl Layered Hydroxides

LiAl layered double hydroxides (LDH) are the promising compounds for application in base catalysis and as precursors of the supports for platinum catalysts. In the work, such systems were synthesized by mechanochemical method. The effect of composition of the initial mixture (Al(OH)3, Al(NO3)3, LiOH, LiNO3), material of milling bodies (steel or ceramic), and activation conditions (centripetal acceleration and activation time) on the properties of LiAl-LDH were studied. It was found that each of the synthesized systems is a polyphase one and contains not only the LDH phase but also the side phase of aluminum trihydroxide. In addition, the samples obtained with the use of steel milling bodies have a substantial amount of iron. The use of ceramic milling bodies makes it possible to obtain the LiAl-LDH phase under relatively mild conditions (acceleration of 300 m/s2 and activation time of 15min).

Solvothermal synthesis of Li–Al layered double hydroxides and their electrochemical performance

In this paper, for the first time, Li/Al layered double hydroxides (LDHs) were synthesized by a facile and environment-friendly solvothermal approach. X-ray diffraction patterns show that the as-prepared products belong to the hexagonal phase. Well-defined LDHs particles with spiral-shape (1–2 μm), hexagonal (2–3 μm) and petal-like structures (10–15 μm) have been successfully fabricated by adjusting the content of water/ethanol in the synthesis process. A possible growth mechanism was proposed for the formation of these structures. Their electrochemical performances were investigated by cyclic voltammetry, galvanostatic charge/discharge test and electrochemical impedance spectroscopy. The hexagonal Li/Al LDHs calcined at 450 °C exhibit the specific capacitance of 848 F g−1 at a current density of 1.25 A g−1. The high specific capacitance and remarkable rate capacity of Li/Al LDHs are promising for applications in capacitors and low-cost aqueous lithium ion batteries.