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Trialkyl-monoacetic acid derivatives of p–t-octylcalix[4]arene and calix[4]arene were prepared to investigate the effect of the alkyl branches attached to the phenoxy oxygen atoms and the p-position on the selective extraction of Li+ over Na+. Alkyl branches on the phenoxy oxygen atoms remarkably affected the Li+ selectivity, whereas those at the p-position had less effect. The former can contribute to excluding Na+ extraction while enabling Li+ extraction. Optimal selection of the alkyl branch improves the Li+ selectivity of calix[4]arene. However, sterically-hindered p–t-octylcalix[4]arene with three 2-ethylbutyl branches exhibited opposite selectivity. [ABSTRACT FROM AUTHOR]

Biological ion channels use the synergistic effects of various strategies to realize highly selective ion sieving. For example, potassium channels use functional groups and angstrom‐sized pores to discriminate rival ions and enrich target ions. Inspired by this, we constructed a layered crystal pillared by crown ether that incorporates these strategies to realize high Li+ selectivity. The pillared channels and crown ether have an angstrom‐scale size. The crown ether specifically allows the low‐barrier transport of Li+. The channels attract and enrich Li+ ions by up to orders of magnitude. As a result, our material sieves Li+ out of various common ions such as Na+, K+, Ca2+, Mg2+ and Al3+. Moreover, by spontaneously enriching Li+ ions, it realizes an effective Li+/Na+ selectivity of 1422 in artificial seawater where the Li+ concentration is merely 25 μM. We expect this work to spark technologies for the extraction of lithium and other dilute metal ions. [ABSTRACT FROM AUTHOR]

Lithium recovery is imperative to accommodate the increase in lithium demand. Salt lake brine contains a large amount of lithium and is one of the most important sources of lithium metal. In this study, Li2CO3, MnO2, and TiO2 particles were mixed, and the precursor of a manganese–titanium mixed ion sieve (M-T-LIS) was prepared by a high-temperature solid-phase method. M-T-LISs were obtained by DL-malic acid pickling. The adsorption experiment results noted single-layer chemical adsorption and maximum lithium adsorption of 32.32 mg/g. From the Brunauer–Emmett–Teller and scanning electron microscopy results, the M-T-LIS provided adsorption sites after DL-malic acid pickling. In addition, X-ray photoelectron spectroscopy and Fourier transform infrared results showed the ion exchange mechanism of the M-T-LIS adsorption. From the results of the Li+ desorption experiment and recoverability experiment, DL-malic acid was used to desorb Li+ from the M-T-LIS with a desorption rate of more than 90%. During the fifth cycle, the Li+ adsorption capacity of the M-T-LIS was more than 20 mg/g (25.90 mg/g), and the recovery efficiency was higher than 80% (81.42%). According to the selectivity experiment, the M-T-LIS had good selectivity for Li+ (adsorption capacity of 25.85 mg/g in the artificial salt lake brine), which indicates its good application potential. [ABSTRACT FROM AUTHOR]

Lithium recovery is imperative to accommodate the increase in lithium demand. Salt lake brine contains a large amount of lithium and is one of the most important sources of lithium metal. In this study, Li2CO3, MnO2, and TiO2 particles were mixed, and the precursor of a manganese–titanium mixed ion sieve (M-T-LIS) was prepared by a high-temperature solid-phase method. M-T-LISs were obtained by DL-malic acid pickling. The adsorption experiment results noted single-layer chemical adsorption and maximum lithium adsorption of 32.32 mg/g. From the Brunauer–Emmett–Teller and scanning electron microscopy results, the M-T-LIS provided adsorption sites after DL-malic acid pickling. In addition, X-ray photoelectron spectroscopy and Fourier transform infrared results showed the ion exchange mechanism of the M-T-LIS adsorption. From the results of the Li+ desorption experiment and recoverability experiment, DL-malic acid was used to desorb Li+ from the M-T-LIS with a desorption rate of more than 90%. During the fifth cycle, the Li+ adsorption capacity of the M-T-LIS was more than 20 mg/g (25.90 mg/g), and the recovery efficiency was higher than 80% (81.42%). According to the selectivity experiment, the M-T-LIS had good selectivity for Li+ (adsorption capacity of 25.85 mg/g in the artificial salt lake brine), which indicates its good application potential.

Nanofiltration (NF) membrane-based separation has gained significant attention as an efficient technology for recovering lithium (Li) from salt-lake brines. However, many previously developed NF membranes are not commercially feasible because they lack sufficient Li selectivity and require the use of new monomers/chemicals or complicated fabrication processes. Herein, we propose a commercially viable method to fabricate ultrahighly Li-selective polyamide (PA) membranes by carefully tailoring a conventional interfacial polymerization process using an established piperazine (PIP)/trimesoyl chloride monomer system. The use of excess PIP endowed the fabricated membrane with enhanced PA crosslinking density and a positive surface charge, reinforcing both its size and Donnan exclusion mechanisms. Furthermore, the addition of benzyltributylammonium chloride, a cationic surfactant, to the PIP solution effectively improved the water permeance of the membrane without impairing its magnesium ion (Mg2+) rejection by loosening its PA network while enhancing its positive surface charge. Consequently, our tailor-made PA membranes with the proper pore structures and strong positive surface charges exhibited ultrahigh Li+/Mg2+ selectivity of up to 150 (under single-salt conditions) and 887 (under mixed-salt conditions), significantly outperforming commercial and other reported laboratory-made NF membranes. Our strategy provides a facile and effective means to manufacture Li-selective membranes with high commercial viability. [Display omitted] • PA membranes are fabricated by tailoring PIP/TMC-based interfacial polymerization. • The use of excess PIP forms a tight PA structure with a positively charged surface. • Adding a cationic surfactant loosens PA while enhancing its positive surface charge. • Tailor-made PA membranes exhibit unprecedentedly high Li+/Mg2+ selectivity. • Tailor-made PA membranes outperform commercial and other lab-made NF membranes. [ABSTRACT FROM AUTHOR]

Extracting lithium selectively and efficiently from brine sources is crucial for addressing energy and environmental challenges. The electrochemical system employing LiMn 2 O 4 (LMO) electrodes has been recognized as an effective method for lithium recovery. However, the lithium selectivity and stability of LMO need further enhancement for its practical applications. Herein, the Al-doped LMO with reduced lattice constant is successfully fabricated through a facile one-step solid-state sintering method, leading to enhanced lithium selectivity. The reduced lattice constant in Al-doped LMO is proved through spectroscopic analyses and theoretic calculations. Compared to the original LMO, the Al-doped LMO (LiAl 0.05 Mn 1.95 O 4 , LMO-Al0.05) exhibits highercapacitance, lower resistance, and improved stability. Moreover, the LMO-Al0.05 with reduced lattice constant can offer higher Li + diffusion coefficient and lower intercalation energy revealed by cyclic voltammetry and multiscale simulations. When employed in hybrid capacitive deionization (CDI), the LMO-Al0.05 obtains a Li + intercalation capacity of 21.7 mg g -1 and low energy consumption of 2.6 Wh mol -1 Li + . Importantly, the LMO-Al0.05 achieves a high Li + extraction percentage (≈86%) with Li + /Na + and Li + /Mg 2+ selectivity of 1653.8 and 434.9, respectively, in synthetic brine. The results demonstrate that the Al-doped LMO with reduced lattice constant could be a sustainable solution for electrochemical lithium extraction., (© 2024 Wiley‐VCH GmbH.)

[Display omitted] • HMO@ZIF-AC electrode in CDI showed higher Li selectivity (2.19) over HMO-AC (0.18). • Zn in HMO@ZIF-AC enhanced Li uptake due to intercalation H+/Li+ exchange tunnel. • Small ZIF cavity size in HMO@ZIF-AC create pathway that enhances Li/Mg selectivity. • HMO@ZIF-AC showed remarkable Li/Na selectivity (1 1 4) at high Na: Li ratio of 96:1. • HMO@ZIF-AC electrode showed reusability, reflected by its repeated operative cycles. Presently, substantial research focus is being placed on alternative lithium (Li) extraction from natural water sources such as seawater and salt brine to meet the growing demand for Li, a crucial component for energy storage. Electrochemical capacitive deionization (CDI) shows promising capacity to rapidly extract Li from brine solutions with selective electrodes. This study fabricated activated carbon (AC)-based Li-selective electrodes with hydrogen manganese oxide (HMO) ion-exchange nanomaterial, HMO@AC, and zeolitic imidazolate frameworks encapsulated HMO (HMO@ZIF-AC) electrodes. The incorporation of HMO@ZIF-AC electrode into CDI resulted in rapid Li-ion adsorption and a notable reduction in Mg-ion uptake compared to HMO-AC electrode. In mixed solutions, HMO@ZIF-AC displayed promising Li selectivity over other ions (ρ Na + Li + = 13.14, ρ K + Li + = 6.60, ρ Mg 2 + Li + = 1.69). Also, HMO@ZIF-AC exhibited enhanced Li selectivity in highly saline conditions (Na: Li molar ratio of 96:1). The high performance of HMO@ZIF-AC compared to HMO-AC was attributed to its higher surface area that provided higher vacant sites and the presence of Zn. This was evident as a significantly higher Li uptake (46–48 %) was achieved with a Zn doped HMO electrode (Zn-HMO-AC) compared to HMO-AC and HMO@ZIF-AC electrodes. Meanwhile, compared to HMO-AC, the high Li to Mg selectivity of HMO@ZIF-AC was attributed to the small cavity size of the activated ZIF, creating specialized pathways for Li ions and impeding the ion conduction of Mg2+. [ABSTRACT FROM AUTHOR]

The demand for lithium (Li) will grow from about 500,000 metric tons of lithium carbonate equivalent in 2021 to 3–4 million metric tons in 2030. To meet the Li demand, the separation of Li-mixed monovalent and divalent cations is critical for Li extraction from an aqueous medium. Capacitive deionization (CDI) and membrane capacitive deionization (MCDI) have recently emerged as viable water treatment technologies, yet ion-specific selective recovery using CDI systems is still under-investigated. In this study, the electrode surface of each system was modified to improve Li+ selectivity. Metal-organic frameworks (MOF), particularly zeolitic imidazolate framework-8 (ZiF-8), have shown substantial promise due to their tunable pore size and pore channel chemistry. Through an aqueous medium-based surface modification, we offer a simple technique of synthesizing ZiF-8 on carbon electrodes and underneath the cation exchange membrane (CEM). The bare CDI and MCDI systems initially showed poor selectivity towards Li+ in the mono and divalent ion incorporated simulated solutions. The relative selectivity (ρ M Li ; (M = metal ions)) in the CDI system was estimated as 0.73, 0.43, 0.67, and 0.58 for Na+, K+, Mg2+, and Ca2+, respectively, which was 0.93, 0.97, 0.39, and 0.30 in the MCDI system. In the case of bare activated carbon (AC) electrodes, the difference of hydration enthalpy played a critical role in Li+ selectivity towards other monovalent ions. However, despite having high hydration enthalpy, the Mg2+ and Ca2+ showed low Li+ selectivity due to the superior charge density of divalent ions. On the other hand, after the modification of AC electrodes with in-situ growth of ZiF-8 on the surface, the Li+ selectivity for monovalent Na+ and K+ was estimated at 3.08 and 1.12, respectively, which is 4.2 and 2.6 times higher than the bare AC electrode, respectively. Besides, compared to Na+, the trade-off between the low dehydration energy of K+ and the rapid ion transit of dehydrated Li+ made separating challenging. Consequently, for divalent Mg2+ and Ca2+, coulombic attraction dominated both in the bare CDI and MCDI systems. This research sheds light on using the newly developed ZiF-8 coating for selective Li recovery. • A Li+ selectivity of 3.08 over Na+ was achieved in a CDI system. • A facile in-situ growth of ZiF-8 on the AC electrode was confirmed. • Successful incorporation of ZiF-8 and CEM on the cathode confirmed high Li+ removal. • The mechanism of Li+ removal from binary equimolar cation mixes was explained. [ABSTRACT FROM AUTHOR]

A series of cone conformational p-t-octylcalix[4]arene derivatives with propyl and/or acetic acid groups have been synthesized and investigated for alkali metal extraction in individual and competitive metal systems. All ion-exchangeable derivatives exhibited extraction ability. Tripropyl-monoacetic acid derivative exhibited lithium selectivity, whereas other derivatives with multiple acetic acid groups exhibited sodium selectivity over lithium in an individual metal system. The significant metal selectivity was observed in a competitive system, because only the preferential metal ion occupied the derivative. A coordinatively-inert lipophilic propyl group or a few introduced on the calix[4]arene contributed to the size-discriminating property not only for the first metal ion but also for the second ion. The metal selectivity is discussed based on structural change before and after metal loading by using H-NMR spectra and an effect of lipophilic propyl groups. [ABSTRACT FROM AUTHOR]

The lithium concentration in seawater is 0.17 mg/L, which is very low, but the overall quantity is approximately 2.5 × 10 14 kg. Therefore, seawater, which contains a vast amount of lithium, could be a major alternative source that might supply the rising demand for lithium. This research was undertaken to evaluate the feasibility of a manganese oxide (HMnO) adsorbent, which was produced after leaching lithium from lithium manganese oxide, for lithium collection from seawater. The HMnO was synthesized and deformed to a plastic after wet blending of manganese oxide and lithium hydroxide, and subsequently, the influence of pH, sorption isotherms, sorption rates, sorption energies, and effects of the co-ions were measured. Thermodynamic parameters such as Δ G ° , Δ H ° , and Δ S ° indicated that the nature of the lithium sorption was both spontaneous and endothermic. The used HMnO could be regenerated by washing it with an HCl solution. The results demonstrated that HMnO could be effectively used for the collection of lithium from seawater with good selectivity. [ABSTRACT FROM AUTHOR]

Lithium is a critical element due to its use in lithium-ion batteries, required for electric vehicles and stationary energy storage devices. Various approaches have been applied to extract it from the available resources. One of the developed lithium-capturing methods is hybrid capacitive deionization (HCDI), where the cathode is made of spinel-type material. This paper presents our study on the most effective Li, Mn, and Ti spinel-type materials, for which we analysed their structure, efficiency for lithium capturing, and energy consumption in the HCDI system. We found spinel with Li:Mn:Ti ratio of 1:3:0.15 to be the best material for lithium recovery. The natural geothermal water was applied for testing lithium recovery by HCDI equipped with the investigated material. By applying the asymmetrical electric mode, the lithium capturing efficiency reached near 80% with 8 min. The separation factors for other cations such as sodium, potassium, calcium, magnesium, and strontium were over three-times smaller. • The optimal ratio of Li:Mn:Ti in spinel-type material is 1:3:0.15. • Advanced material analysis of investigated adsorbents • Selective removal lithium with separation factor Li/cation over 3 • Recovery rate of lithium is 36%. [ABSTRACT FROM AUTHOR]

Stilbenophanes 1c and 2c were synthesized in good yields. Among alkali ions, both isomers only formed 1:1 complexes with lithium selectively. An X-ray structure of 1c shows a statistical disorder which leads to two refined positions for the ethylene moiety. The existence of a weak intramolecular C-H⋯O hydrogen bond in its structure was confirmed by both X-ray analysis and theoretical calculation. [ABSTRACT FROM AUTHOR]

Solid-phase reactions were used for the synthetization of the spinel Li 1.6 Mn 1.6 O 4 powder and the lithium ion-sieve MnO 2 ·0.5H 2 O was subsequently obtained by the leaching of the lithium. The physical characterization showed that the polycrystalline precursor and the MnO 2 ·0.5H 2 O were nearly pure spinel, as well as that during the process of the adsorption-desorption, the structural stability was high. The Langmuir isotherm and pseudo second-order kinetics model showed consistency with the adsorption behavior, which indicated the presence of homogeneous adsorption sites for the lithium adsorption and that its process was chemisorption. Adsorbents were found to remain being characterized with a relatively high Li+ uptake (26.13 ​mg ​g−1) with low manganese extracted (1.71%) after the circulation experiment was performed up to 5 times, proving a significant repeatability and stability for the lithium ion-sieve. The concentration factors exhibited the highly selective adsorption capacity for absorbent from Qarhan raw brine with high concentrations of Na+, K+, Ca2+, Mg2+. The adsorbents could be efficiently used for Li+ recovery from Salt Lake brine as well as its excellent potential for further application. Due to the sieving effect (steric hindrance effect and hydration free energy effect), the lithium ion-sieve selectively adsorbed Li+ when the ion-sieve was immersed in brine, indicating that the ion-sieve MnO 2 ·0.5H 2 O was expected to recover Li+ from the solutions including Salt Lake brine, seawater, and wastewater. Image 1 • The precursor was prepared by practical two-stage solid-phase sintering technique. • The Li 1.6 Mn 1.6 O 4 exhibited excellent adsorption performance. • The materials showed the highly selective adsorption from Qarhan raw brine. [ABSTRACT FROM AUTHOR]

• Lithium-manganese-iron oxides preparation. • SEM, EDS, BET, XRD and surface energetics evaluations. • Constant current and constant voltage modes and their combinations. • Application multicomponent solutions to HCDI process. • Lithium selectively capturing from aqueous solutions. In this paper, studies on extraction of lithium using a new desalination technology are presented. We discovered novel spinel type material based on lithium-manganese and iron compounds that was prepared by high temperature sintering method. The structure and porosity of the adsorbents were investigated by SEM, EDS, XRD and BET analyses, while the pore size distribution was calculated according to the DFT model. The adsorbent with molar ratio of Li/Mn and Li/Fe of 1.5:1 exhibit the best structure performances. This material was used to build a negatively polarized electrode that allowed – 32 mg/g salt adsorption capacity for LiCl as well as 16 mg/g and 0 mg/g for NaCl and KCL, respectively. Additionally, developed system was applied to removal lithium ions from multicomponent solution. To do this, the different electric sequences were employed. By application modified electrical mode it could be possible release lithium ions from multicomponent solutions with over 76% efficiency and reduce the ratio Na:K:Li from 227:1.1:1 to 2.9:0:1 after one cycle of the separation process. [ABSTRACT FROM AUTHOR]