The rational design of high-performance adsorbents for lithium recovery from aqueous resources depends critically on understanding how metal doping modulates the structure and properties of metal-organic frameworks (MOFs). In this work, we systematically investigate the effects of Fe doping on the lithium adsorption and isotope separation performance of Al-MOFs through controlled synthesis of bimetallic Al/Fe-MOFs with varying metal ratios (1:4 to 4:1). The materials were characterized by XRD, XPS, TGA, and adsorption experiments, complemented by density functional theory calculations. Results show that optimal Fe incorporation (Al/Fe = 2:1) significantly improves Li+ adsorption capacity (24.07 mg g(-1)) and isotopic selectivity (alpha = 1.033) compared to the undoped MOFs (Q = 12.97 mg g(-1), alpha = 1.027). Structural analyses reveal Al/Fe-MOFs contraction (Delta d (002) = 0.36 angstrom) and surface charge modification (pH (ZPC) shift from 10.26 to 8.73), while electronic structure studies demonstrate Fe3+/Fe2+ redox activity promotes electron transfer. DFT calculations identify greatly increased adsorption energetics (-3.96 eV) through synergistic Al-O/Fe-O interactions, where the rigid Al-O framework ensures structural stability and flexible Fe-O sites support dynamic adsorption. The material exhibits excellent cycling stability (92 % capacity retention) due to dual stabilization mechanisms. These findings confirm that balanced bimetallic coordination in MOFs can enhance adsorption capacity and selectivity through geometric and electronic effects, providing valuable insights for designing advanced adsorbents for lithium recovery.

Lithium isotope separation is a crucial technology with applications in nuclear energy and advanced material science. This study explores the lithium adsorption and isotope separation capabilities of aluminum-based metal-organic frameworks (Al-MOFs), notably MIL-53, DUT-4, DUT-5, MIL-120, and MIL-122, synthesized by altering organic ligands. Among them, MIL-120 demonstrated the highest lithium adsorption capacity, with a maximum uptake of 141.4 mg & sdot;g- 1 at 25 degrees C, driven by physisorption mechanisms. At the same time, DUT-5 excelled in lithium isotope separation, achieving a single-stage separation factor (alpha) of 1.026 and a delta (7Li) value of -18.03. Adsorption thermodynamics indicated that the process for MIL-120 and MIL-122 was endothermic with Delta H theta = 58.96 kJ & sdot;mol- 1, while MIL-53, DUT-4, and DUT-5 followed a chemisorption pathway (Delta H theta = 184.68 kJ & sdot;mol- 1). Structural and thermogravimetric analyses revealed distinct dehydration and binding behaviors, with MIL-120 facilitating surface adsorption of Li(H2O)+ 4 complexes and DUT-5 promoting chemisorption through Li-O interactions. Density functional theory (DFT) calculations confirmed that electrostatic interactions with oxygen sites facilitate lithium adsorption of MIL-120, whereas DUT-5 forms stronger Al-O-Li bonds via partial dehydration. The materials exhibited excellent stability, retaining over 90 % of adsorption capacity after five regeneration cycles. These findings highlight the potential of Al-MOFs in the field of lithium isotope separation and recovery technologies.

The separation of lithium isotopes is of great importance to the development of the nuclear indus-try.The effect of factors such as electric field,crown ether,time on lithium isotope separation effect was in-vestigated systematically based on"aqueous solution|organic solution|aqueous solution"electromigration system.It was found that the introduction and enhancement of electric field improved the migration ability of lithium ions in organic solution.The anode solution and organic solution tended to enrich 7Li,while the cathode solution tended to enrich 6Li.The introduction of crown ether significantly enhanced the enrichment of lithium isotope in each section of the system.The anode solutions and organic solutions tended to enrich 7Li,and the cathode solutions tended to enrich 6Li.There is a synergic effect of electromigration,chelation and diffusion in the electromigration process of lithium isotope separation.The two chemical forms of lithium ions complexed with crown ether and not complexed with crown ether in organic solution have dif-ferent response to high-pressure electric field(≥10 V).The lithium isotope enrichment in each section of the system depended on the combined action of above factors.

In addressing challenges in Selective Catalytic Reduction (SCR) systems in vehicles, the development of novel SrCl2 composite materials with high ammonia adsorption and structural stability is crucial. In this context, we employed the porous magnesium oxychloride cement (PMOC) as a carrier material, successfully fabricating a mesoporous PMOC-SrCl2 material via solution impregnation technology. Simultaneously, we employed various characterization techniques such as XRD, full-pore analysis, TG, SEM, TEM, and EDS to examine the material. We conducted static adsorption assessments on numerous candidate materials at 0.1Mpa and 293.15 K. The synthesized C3 series material (Mass ratio of SrCl2 to PMOC = 10:3), solution impregnated for 1 h, exhibited exceptional ammonia adsorption capacity (up to 38.01 mmol center dot g(-1)). Through model fitting of experimental data, we discovered that the adsorption process of this material closely aligns with the pseudo-second-order kinetic model and the Langmuir model. Over an adsorption time span of 180 min, the adsorption rate of the composite material increased by 129 % compared to pure SrCl2. In the cycle performance testing phase, we observed that the material exhibited no significant degradation in performance after undergoing 10 cycles of adsorption/ desorption. This structurally stable, cost-effective, and readily accessible high-efficiency ammonia adsorption material undoubtedly possesses immense potential to solve the application challenges of ammonia adsorption materials within automotive selective catalytic reduction systems.

This study is based on the system of "anodic aqueous solution | crown ether-ionic liquid organic solution | cathodic aqueous solution", the influence of ionic liquid ratio in organic solution under different voltages on Li+ transport and lithium isotope separation was investigated. It is found that ionic liquids have multiple roles. In addition to improving the conductivity of organic solutions and enhancing Li+ transport capacity between aqueous solution and organic solution through ion exchange. Ionic liquids are even to realize the migration of lithium ions from aqueous solution to organic solution through solvation. There is an obvious synergistic enhancement between ionic liquid solvation and electric field. Based on this, three types of Li+ transport across the aqueous-organic interface are proposed. The influencing mechanism of ionic liquid ratio, voltage on Li+ migration ratio and lithium isotope separation is discussed in detail.

High abundance 6Li and 7Li are essential materials for the nuclear industry. In this article, the lithium isotope separation effect and lithium-ion transport of a "lithium salt aqueous solution (anolyte)|crown ethers-ionic liquid organic solution|ammonium chloride aqueous solution (catholyte)" electromigration system with B12C4, B15C5 and B18C6 as phase transfer catalysts were investigated systematically. The results show that separation factors can reach 1.028 (B12C4), 1.024 (B15C5) and 1.011 (B18C6), respectively, when LiCl solution is used as the anolyte. The separation effect mainly originated from interfaces between anolytes and organic solutions, and was less affected by an electric field. The separation effect between organic solution and catholytes was greatly affected by the electric field for B12C4 and B15C5 systems, which converted from 7Li-enrichment to 6Li-enrichment with increased voltage. For the B18C6 system it was less affected. Furthermore, lithium ion transport in B12C4, B15C5 and B18C6 systems was greatly promoted by the electric field, with the Li+ concentration in catholytes of B12C4, B15C5 and B18C6 systems increased from 0.088 mg L-1, 0.286 mg L-1 and 0.778 mg L-1 to 8.321 mg L-1, 7.422 mg L-1 and 4.631 mg L-1 respectively as the voltage increased from 2 V to 16 V. The B12C4 system has been confirmed as the optimal solution considering both the Li+ transport and isotope separation effect. In the aqueous-organic biphasic electromigration system, the larger cavity size of crown ethers, the weaker binding between crown ethers and Li+, and the lower dissociating voltage of complexes and initial voltage enriching 6Li in the catholyte.

A new system for enrichment of 7Li by solvent extraction method. In the present work, a new system for the extraction and enrichment of 7Li was constructed, and provides a new idea for the separation of 7Li by extraction method.

B12C4 systems achieve better 6Li enrichment in the organic phase and B15C5 systems achieve better 7Li enrichment in the aqueous phase.

This paper reported a novel chelating agent and a green precipitation-extraction separation strategy for lithium isotope enrichment. 1-Hydroxy-4-(p-toluidino) anthraquinone and anisole were used as chelating agent and diluent, respectively. Three phases including organic phase, aqueous phase and precipitation could be preparated. The experiment indicated that excess sodium hydroxide was helpful to promote the single-stage precipitation rate and equilibrium time. The isotope result indicated that 6Li was concentrated in the aqueous phase and 7Li was concentrated in precipitation phase. The maximum single-stage lithium isotope speration factor reached to 1.013 +/- 0.001. By doing thermodynamic analysis of the reaction, the free energy change (Delta G), enthalpy change (Delta H) and entropy change(Delta S) of the separation process were -8.97 J mol- 1, -21.37 J mol-1 and -0.0438 J mol-1 K-1 at 283 K. The results of DFT simulation and wave function analysis indicated that a lithium ion combined with a chelating agent anion formed a stable six-member ring between two oxygen, which was more stable than sodium ions combined with chelating agent anions (the Gibbs free energy of the lithium ions reaction was more negative). As interaction analysis result showed, the Li-O bond in complex interaction was significantly stronger than the Li-O bond interaction in aqueous phase, which was the theroy that led to the enrichment of 7Li in organic phase. In the activated carbon treatment experiment, it was found that part of lithium chelator solved in aqueous phase, which resulted in that the lithium abundance of aqueous phase hardly changed. In order to increase the abundance of 6Li in aqueous phase, it is necessary to add adjuvant to reduce the water solubility of lithium chelate. Overall, an economical and environmental-friendly precipitation method with a certain application prospect for lithium isotope separation was proposed, and the direction of improving the separation performance was pointed out in this paper.

Both lithium-6 and lithium-7 with high abundance are indispensable materials in nuclear industry. Here, an aqueous solution│organic solution│aqueous solution system was fabricated to separate lithium isotopes. The effects of species and concentration of electrolytes in the electrode solutions on the lithium ions migration and lithium isotope separation with different voltages and migration time was studied. It was found that lithium-7 was enriched in aqueous solutions on both sides at 0 V and 2 V, while lithium-7 was enriched in anode solution and lithium-6 was enriched in cathode solution at 16 V. The weakening stability of the chelate consisted of crown ether and lithium ion with increasing voltage was believed to the possible reason. Meanwhile, the variation of electrolyte in electrode solution led to notable changes in migration ratio of lithium ions and lithium isotope separation effect, which can be attributed to the different degree of both ionization and hydrolysis for various electrolytes in aqueous solutions and the different ability of H+ and NH4 + to replace Li+ of chelate in organic solutions. This work is of great significance for the selection of electrode solutions in electromigration separation of lithium isotopes and even other electrochemical systems.

Li-6 and Li-7, two natural isotopes of lithium, play an important role in the nuclear industry. Here, a system of ionic liquid-crown ether was fabricated for lithium isotope separation and the Li-6 isotope separation coefficient can reach 1.406 that showing a good prospect for lithium isotope separation by this method of electromigration. Interestingly, the single crystal containing crown ether and lithium, in which Li-7 was enriched, was obtained from the experiments. It is contrary to popular wisdom and can be attributed to the steric hindrance effect. This provides a new route to separate lithium isotopes, that is electromigration coupling with crystallization.@ 2022 Elsevier B.V. All rights reserved.

Flotation complexation extraction can effectively extract and separate lithium isotopes. The effects of nitrogen flow rate, bubble size, gas holdup, reaction flow pattern, aeration time, and temperature on the separation process were studied. In addition, the complex relationship and separation mechanism of lithium with 10-hydroxyquinoline were discussed. Results show that nitrogen flow rate and bubble size significantly affected the flotation complexation extraction process. With an appropriate flow rate, we obtained a homogeneous regime pattern containing small and evenly distributed bubbles to achieve better separation efficiency and ensure a smooth extraction process. According to the slope method, lithium and 10-hydroxybenzoquinoline were complexed and extracted at a ratio of 1: 2. Compared with the traditional oscillating extraction, the bubble mass transfer mode in the flotation complexation extraction strengthened the complex extraction process and achieved higher extraction rate and separation efficiency.

The evolution of the nuclear industry is inextricably linked to lithium isotopes. With its distinct benefits, the solvent extraction approach is projected to achieve industrial separation of lithium isotopes. However, the lack of studies on the extraction process conditions and mechanisms has limited the devel-opment of multi-stage processes. In this paper, based on the 4-NO2-B15C5/[BMIm][NTf2] system, the pro-cess conditions and extraction mechanism of the system were investigated by thermodynamic and kinetic studies. The results indicate that lithium isotope separation is a spontaneous exothermic process controlled by diffusion. In addition, DFT calculations show that the binding sites of crown ether and Li+ are located in the coronary heart of crown ether, and electrostatic and van der Waals forces mainly exist between them. On this basis, a 10-stage cross-flow extraction experiment was carried out using crown ether as the extractant. The aqueous phase feed solution is fully utilized, and the 7Li abundance is increased to 93.29 %. In summary, this research provides a foundation for the development of synergistic multi-stage extraction techniques in the future. (C) 2022 Elsevier B.V. All rights reserved.

Lithium and lithium isotopes are important for clean energy development. By introducing ionic liquid, the extraction performance of crown ethers for lithium ions can be significantly improved. However, the enhancement mechanism of ionic liquids in the system is not clear, which directly limits the selection of suitable ionic liquids for various applications. In this work, the synergy mechanisms of different ionic liquids with crown ether during the extraction process were investigated by molecular dynamics simulations and verified by experimental results. There were two molecular mechanisms to capture lithium ions for ionic liquids in the crown ether system: co-extraction and assisted extraction. It was generally considered that the cation exchange mechanism was responsible for the extraction of lithium ions in the crown ether-ionic liquids system. Here, a novel perspective was revealed that one [Li·H2O]+ complexed with crown ether and then the chelate cation coordinated with the anion of the ionic liquid to form a neutral molecule based on the simulation of the whole extraction process with molecular dynamics that favored the transport of Li+ from aqueous solution to organic solution. In the system without ionic liquids, Li+-crown ether chelates were distributed only at the interface and did not enter the organic phase which is supported by very low extraction efficiency. It was attributed that charge equilibrium cannot be achieved when Li+-crown ether chelates enter into organic solution in the absence of ionic liquids. Overall, a new insight into the interfacial transport mechanisms of lithium ions was proposed, in which the anion of ionic liquids played a key role in capturing lithium ions at the interface of aqueous solution and organic solution.

Controlled fusion energy is considered to be one kind of sustainable energy source with clean and green properties. The fusion process requires a large number of lithium isotopes, but the naturally stable lithium isotopes 6Li and 7Li cannot be directly applied to the fusion process and must be further enriched. In this paper, a system for the separation of lithium isotopes by extraction was investigated, which mainly consists of bromobenzene-15-crown-5 and ionic liquids. The effects of ionic liquids, lithium salts, crown ether concentration, and temperature on the separation performance of lithium isotopes were explored. It was found that 6Li was enriched in the organic phase and the single-stage separation factor reached 1.032. It was proved by the temperature experiment that the exchange of lithium isotopes was a spontaneous and exothermic process. The complexation ratio of crown ether and lithium ions was 1:1. The optimized complexation model and the interaction of crown ether and lithium ions were calculated by DFT and Multiwfn. Lithium ions were weakly bonded to the crown ether and strongly bonded to the water molecule as demonstrated by the non-bonded interactions and Mayer bond order of Li-O. Meanwhile, the mechanism of lithium isotope separation with crown ether was clarified by mutual ver-ification of experiment and theoretical calculations.(c) 2022 Elsevier B.V. All rights reserved.

Effective separation of lithium isotopes (6Li and 7Li) is a significant challenge in developing clean nuclear energy. In this work, 7Li was separated and enriched by 10-hydroxybenzoquinoline using flotation complexation extraction under alkaline conditions. In addition, the thermodynamic process of lithium isotope separation was discussed and the separation mechanism was explained by theoretical calculation according to density functional theory. Finally, the conditions of the Li+ stripping process were investigated. The results showed that the single-stage separation factor was 1.023 ± 0.001, and the abundance of 7Li reached 92.72%. The stripping ratio of lithium reached 98% by stripping five times using pure water.

Lithium isotopes (Li-6 and Li-7) play an important role in the nuclear industry. The development of green and efficient separation methods is a top priority for the lithium isotope industry. In this work, an "aqueous solutionlionic liquid-crown ether organic solutionlaqueous solution" system was constructed and used for lithium isotope electromigration separation. The influence and synergy of Li+ diffusion, electromigration, and chelation of crown ether on Li+ migration and isotope separation were investigated, discussed, and verified carefully. The separating laws were summarized. The process and mechanisms of lithium isotope separation were explored preliminarily. The presence of crown ether in organic solution and the introduction of electric field can change the migration ratio and lithium isotope enrichment effect of different parts in the system. The synergy of Li+ diffusion, electromigration, and chelation of crown ether can change the behaviors of Li+ migration and isotope separation significantly. What's more important, the driving forces are not constant but dynamic. The diffusion increased with the increasing concentration gradient among different parts. The chelation decreased with the increasing Li+ concentration in organic solution. The electromigration also changed with the varied chemical speciation of Li+. The results helped in understanding the roles of driving forces more clearly and provided a foundation for developing green and efficient methods for lithium isotope separation.

The high-abundance lithium isotopes are key materials for the development of the nuclear industry. Lithium amalgamation is currently the only industrial method to produce lithium isotopes, but serious environmental pollution problems exist. Electromigration separation is one of the green and promising alternatives. Here, a “lithium salt aqueous solution │ organic solution │ aqueous solution” system was fabricated for lithium isotope separation. The effects of solute species and concentration in the catholyte with different voltages and migration time on the variation of pH in the electrolyte, lithium ions migration, and isotope separation were investigated. It was found that the pH of the catholyte will have an effect on the pH of the anolyte and the pH of the electrolyte changes dramatically in the process of electromigration. While the variation is unfavorable for the migration of lithium ions and isotope separation, competition experiments, and DFT simulation to further elucidate the influence mechanism. In addition, an extremely high 6 Li isotope separation coefficient (1.6) was obtained at a very low lithium ions migration ratio, which showed a good prospect for lithium isotope separation by this system. This work provides important guidance to understand the electromigration process of this system and select the better electrolyte.

Azacrown ethers contain multiple coordination sites, which show specific complexation to alkali metal ions. In this research, a neoteric liquid-liquid extraction system was investigated for the selective separation of lithium isotope using N-phenylaza-15-crown-5 (Ph-N15C5) as chelating agent and [BMIm][ NTf2] and anisole as extraction solvent. The effects of the counter anions of lithium salt, concentrations of crown ether, temperature, extraction equilibrium time and concentrations of lithium salt solution on the separation of lithium isotope with Ph-N15C5 were studied. The maximum extraction efficiency of lithium ions was 41.54% and the maximum single-stage separation factor (alpha) of Li-6/Li-7 obtained in the present study was 1.025, indicating that the lighter isotope Li-6 was enriched in organic phase while the heavier isotope Li-7 was concentrated in the aqueous phase. The complexation ratio of the lithium crown ether complex was determined as 1:1 by the slope analysis method. The lithium ions in the aqueous phase were extracted into the organic phase to form [Li(Ph-N15C5)](+) complex. The thermodynamic data obtained at different temperatures demonstrated that lithium isotope exchange was a spontaneous exothermic process, and lowering the temperature was beneficial to increase the separation factor. In addition, the system reached the extraction equilibrium after 60 min. This high efficiency and green liquid-liquid extraction system has potential application in lithium isotope separation. (C) 2021 Elsevier B.V. All rights reserved.

The ions electromigration of ionic liquids(ILs)/aqueous solution binary system have attracted increasingly attention in many fields.In this work,the effect of acidity-alkalinity,electrolyte concentra-tion of electrode solutions and ILs with LiN(CF3SO2)2 on the migration of[C6MIm]+ ions was investi-gated systematically by studying the concentration change of ions of ILs in the electrode solutions.Gener-ally,the concentration of[C6MIm]+ ions increased in cathode solution and decreased in anode solution with increasing current,while the concentration of N (CF3SO2) 2-ions increased in anode solution and decreased in cathode solution.When basic solution was used as electrode solution,the migration of[C6 MIm]+ ions was restrained markedly.LiN (CF3SO2) 2 solution was used as electrode solution and the dissolution of LiN(CF3SO2)2 in ILs could reduce the migration of[C6MIm]+ ions effectively.