Lithium Ion Sieve Research Articles

Synergistic effect of Fe/Zr dual doping endows hydrophilic spinel-structured H4Ti5O12 ion sieves for efficient lithium extraction from liquid resources

The practical application of spinel-structured H4Ti5O12(HTO) lithium-ion sieves (LISs) is hampered by their poor adsorption properties and recyclability. Within this research, the surface properties and internal structure of lithium-ion sieve (LIS) materials were modulated by co-doping Fe and Zr metal ions to enhance their adsorption properties. The results show that Fe and Zr have been successfully introduced to the LIS lattice, increasing Li-O bond length of position 8a and O2− content. The synthesized H4Ti4.77Fe0.2Zr0.03O12 (HTFZO-II) LIS was made up of evenly distributed nanosheets layered on top of one another to create an open laminar structure, which possesses a hydrophilic surface (contact angle: 17.8°), a high surface area (95.89 m2/g), and hierarchical porous structure. Compared with the undoped HTO, the HTFZO-II LISs enjoy a high capacity for Li+ adsorption (28.72 mg/g), a strong cycling stability (Ti4+ dissolving loss: 0.12 %), and a fast reaching of the equilibrium in adsorption (adsorption equilibrium: 4 h). Theoretical calculation of DFT shows that Li(H2O)4+ on HTFZO-II and HTO dehydration were partially dehydrated into Li(H2O)+. The energy required for the dehydration of Li(H2O)4+ on HTFZO-II is lower than that on undoped HTO, indicating that metal ion doping modification was beneficial for the dehydration of hydrated lithium ions on the adsorbent surface, thereby accelerating the exchange reaction between H+ and dehydrated Li+ ions. This study reveals the key role of the synergistic effect of multi-element co-doping in enhancing the adsorption performance and structural stability of LISs.

Fabrication of N,C-H2TiO3 Ion Sieves for Rapid Adsorption of Lithium Using Rheological Phase Methods

Modifying β-H2TiO3 by elemental doping improves its adsorption capacity and shortens the equilibrium adsorption time, which is of positive significance for its industrial application.Herein, a novel N, C co-doped Li2TiO3 lithium ion sieve precursor N,C-Li2TiO3-3 (noted as N,C-LTO-3) was successfully prepared via the rheological phase method using urea as a vital raw material. Crystal structure of N,C-LTO-3 was characterized via XRD, XPS, FT-IR, and Raman. The morphology of N,C-LTO-3 was analysed by SEM and HR-TEM. The N,C-LTO-3 was pickled and obtained to N,C-H2TiO3-3, namely N,C-HTO-3. The equilibrium adsorption capacity (Qe) of N,C-HTO-3 was as high as 40.6mg⋅g-1 in LiOH solution of 100mg·L-1 at 293K. Ti4+ dissolution loss rate is below 0.5% in the fifth cycle. Adsorption isothermal curve, kinetics, and thermodynamic behaviour were fitted with the according equations. The exchange energy of N,C-HTO-3 for Li+ was calculated by density functional theory (DFT) to assess the feasibility of lithium absorption. Furthermore, N,C-HTO-3 exhibited high regeneration and selectivity for Li+ in lithium-containing brine, making N,C-HTO-3 an ideal candidate for Li+ extraction.

PVA-enhanced green synthesis of CMC-based lithium adsorption films

The titanium-based lithium ion sieve (HTO), renowned for its exceptional adsorption performance and cyclic stability, was utilized in addressing the global shortage of lithium resources. However, the recovery and reuse efficiency of HTO in powder form is relatively low, which limits its application in industrial fields. To address this issue, this study utilized carboxymethyl cellulose (CMC) as the principal matrix material, while polyvinyl alcohol (PVA) played a dual function as both matrix and crosslinker, negating the necessity for supplementary crosslinking materials. Employing water as the only solvent, HTO was embedded into the CMC-PVA blended film matrix. It was observed that augmenting the CMC content substantially elevates the adsorptive capability of the film. However, this enhancement comes at the cost of reduced mechanical robustness and diminished stability in solution. Consequently, by balancing the influence of adsorptive capacity and stability through fine-tuning the CMC-to-PVA ratio. Even when HTO powder is encapsulated within the film, the adsorption film retains the excellent adsorption properties of HTO, achieving an adsorption capacity for lithium of 29.21 mg g−1 within 12 h. This study provides an innovative pathway and ideas for the large-scale, low-cost production of sustainable lithium-ion adsorption materials.

Synthesis of doped titanium-based lithium adsorbents with excellent stability and adsorption performance by solid state reactions

Titanium-based lithium-ion sieves (LTO) are often employed for lithium recovery from solutions due to their high adsorption uptake. To further reduce the Ti dissolution loss rate and enhance the adsorption performance of LTO, metal-doping was conducted using solid-state reactions in this work, and the effects of incorporated metal elements and doping amounts were investigated. The results indicated that, the doping of 5 % tungsten (W), zirconium (Zr) or cerium (Ce) significantly reduces the titanium dissolution rate from 1.52 % (without doping) to 0.77 %, 1.1 %, and 1.17 % respectively, while the doping of iron (Fe) and molybdenum (Mo) increases the Ti dissolution rate. Simultaneously, the dissolution rates of W, Zr, and Ce (0.15 %, 0.27 %, and 0.66 %) are also significantly lower than those of Fe and Mo (14 % and 24 %). In addition to the record-breaking reduction in the titanium dissolution rate, W doping also substantially enhances the saturated adsorption capacity of lithium to 48 mg g−1 (at 30 °C), 1.37 times that of the undoped LTO (35 mg g−1), demonstrating great potential for lithium recovery.

A Hollow Hemispherical Mixed Matrix Lithium Adsorbent with High Interfacial Interaction for Lithium Recovery from Brine

Mixed matrix lithium adsorbents have attracted much interest for lithium recovery from brine. However, the absence of an interfacial interaction between the inorganic lithium-ion sieves (LISs) and the organic polymer matrix resulted in the poor structural stability and attenuated lithium adsorption efficiency. Here, a novel hollow hemispherical mixed matrix lithium adsorbent (H-LIS) with high interfacial compatibility was constructed based on mussel-bioinspired surface chemistry using a solvent evaporation induced phase transition method. The effects of types of functional modifiers, LIS loading amount, adsorption temperature and pH on their structural stability and lithium adsorption performance were systematically investigated. The optimized H-LIS adsorbent with the LIS loading amount of 50 wt.% possessed the structural merit that the LIS functionally modified by dopamine exposed on both the inner and outer surfaces of the hollow hemispheres. At the best adsorption pH of 12.0, it showed a comparable lithium adsorption capacity of 25.68 mg·g−1 to the powdery LIS within 4 h, favorable adsorption selectivity of Mg/Li and good reusability that could maintain over 90% of lithium adsorption capacity after the LiCl adsorption—0.25 M HCl pickling-DI water cleaning cycling processes for three times. The interfacial interaction mechanism of H-LIS for lithium adsorption was innovatively explored via advanced microcalorimetry technology. It suggested the nature of the Li+ adsorption process was exothermic and dopamine modification could reduce the activation energy for lithium adsorption from 15.68 kJ·mol−1 to 13.83 kJ·mol−1 and trigger a faster response to Li+ by strengthening the Li+-H+ exchange rate, which established the thermodynamic relationship between the structure and Li+ adsorption performance of H-LIS. This work will provide a technical support for the structural regulation of functional materials for lithium extraction from brine.

Advancing Lithium Extraction: A Comprehensive Review of Titanium-Based Lithium-Ion Sieve Utilization in Geothermal Brine

Advancing Lithium Extraction: A Comprehensive Review of Titanium-Based Lithium-Ion Sieve Utilization in Geothermal Brine

Eliminating the effect of pH: Dual-matrix modulation adsorbent enables efficient lithium extraction from concentrated seawater

Lithium ion sieve adsorbents frequently extract liquid lithium resources due to their adsorption effect and cost advantages. However, the adsorption effect is significantly influenced by the ambient pH. The pH effects on the adsorption process can be categorized into two main areas: the competition adsorption of impurity ions and the difference in surface zeta potential. A dual-matrix modulation adsorbent was prepared, comprising a carrier matrix modified with zwitterionic quaternary ammonium bases and an adsorption matrix modified with carboxylation. The zwitterionic quaternary ammonium base groups were employed to mitigate the competitive adsorption of impurity ions by acid-base neutralization. Furthermore, the negative charge of carboxyl groups was employed to diminish the discrepancy in surface zeta potential. The adsorption effect of the ion sieve adsorbent under natural conditions appeared to be significantly enhanced by the dual-matrix modulation, with the saturated adsorption capacity (28 mg/g) and adsorption selectivity (α(Li+/Mg2+)=24.23) being 6.3 and 7.8 times higher than that of the manganese-based adsorbent (HMO) under the same conditions, respectively. Moreover, the adsorption effect was found to be consistent with HMO under alkaline conditions. The results demonstrate that by optimizing the adsorption conditions of the adsorbent, the detrimental impact of pH on the adsorption process of lithium ion sieves can be eliminated.

Preparation, Characterization, and Adsorption Performance of H2TiO3 Lithium Ion Sieves with Homogeneous Nanoparticles: Kinetics, Thermodynamics, and Mechanism Analysis

AbstractLi2TiO3 precursor with layered structure is successfully prepared by template‐free method using anatase TiO2 and Li2CO3, followed by the treatment of dilute hydrochloric acid, which leads to obtaining H2TiO3 lithium ion sieve nanoparticles with uniform dispersion and small size. The adsorption performance and mechanism of the H2TiO3 are being studied. The experimental results show that the H2TiO3 lithium ion sieve has a large BET specific surface area (19.10 m2 g−1) and good thermal stability. At the same time, it also has a high adsorption rate and adsorption capacity (55.13 mg g−1) towards Li+ in solution due to its high dispersibility and uniformity of particle size, which can expose more adsorption sites in LiCl solution. The adsorption capacity of the H2TiO3 lithium ion sieve can reach 46.63 mg g−1, which achieves 84.58% of the equilibrium adsorption capacity. The equilibrium adsorption parameters follow the Langmuir model perfectly, demonstrating that Li+ undergoes monolayer adsorption. The results of thermodynamic and kinetic analysis show that the adsorption behavior of H2TiO3 is spontaneous and conforms to the pseudo‐second‐order kinetic model, indicating the adsorption process is controlled by chemosorption. In addition, after five adsorption/desorption cycles, the H2TiO3 lithium ion sieve still shows a high adsorption capacity of 46.15 mg g−1, and the dissolution loss of titanium is only 0.14%, which shows that the cycle stability is excellent. XPS and zeta potential analyses illustrate that the adsorption mechanism of Li+ on the H2TiO3 is an ion exchange reaction between Li+ and H+, combined with the electrostatic attraction of the adsorbent surface. Additionally, the adsorption performance of H2TiO3 lithium ion sieve in West Taijinaier Salt Lake brine was tested, and the adsorbent material proves itself is a perspective candidate for lithium extraction from aqueous lithium resources.

Predicting the performance of lithium adsorption and recovery from unconventional water sources with machine learning

Selective lithium (Li) recovery from unconventional water sources (UWS) (e.g., shale gas waters, geothermal brines, and rejected seawater desalination brines) using inorganic lithium-ion sieve (LIS) materials can address Li supply shortages and distribution issues. However, the development of high-performance LIS materials and the optimization of recovery-related operating parameters are hampered by the variety of production methods, intricate procedures, and experimental expenses. Machine learning (ML) techniques offer potential solutions for enhancing LIS material development. We collected literature data on Li adsorption, categorizing 16 parameters into adsorbent parameters, operating parameters, and solution components. Three tree-based algorithms—Random Forest (RF), Gradient Boosting Decision Trees (GBDT), and Extreme Gradient Boosting (XGBoost)—were used to evaluate the impact of these parameters on lithium adsorption. The grouped random splitting method limited data leakage and mitigated overfitting. XGBoost demonstrated the best performance, with an R² of 0.98 and a root-mean-squared error (RMSE) of 1.72. The SHAP values highlighted that operating parameters were the most influential, followed by adsorbent parameters and coexisting ion concentrations. Therefore, focusing on optimizing operating parameters or making targeted improvements on LIS based on operating conditions will enhance LIS performances in UWS. These insights are crucial for optimizing Li adsorption processes and designing effective inorganic LIS materials.

Lithium Metal Recovery from Sea Water by a Flexible and Scalable Membrane with Lithium-Ion Exclusive Channels.

Sea water is abundant in lithium reserves, and extracting lithium metal from it holds the potential to not only mitigate the shortage of lithium in light of the fast-growing electric vehicle industry, but also serve as an anode electrode to provide electricity. The task, however, is challenging due to the harsh reactions and low lithium concentration in sea water. Here, we present a single-channel strategy based on a flexible and scalable lithium ion-sieve membrane for efficient lithium extraction. Our composite membrane exhibits high separation factor βLi/Na of more than 2.87 × 107 with an ionic conductivity of 6.2×10-5 S cm-1. Lithium metal was electrolytically extracted from sea water through a hybrid-electrolyte system, which yielded a high Coulombic efficiency of 98.04% and a low energy consumption of 17.4 kWh kgLi-1 at an optimized extracting current of 200 μA cm-2. The extracted lithium metal can be directly integrated into a lithium-sulfur battery, delivering an energy output of 395 Wh kg-1. To demonstrate its industrial viability, we also fabricate a pouch cell with Li metal anode extracted by an amplified extraction prototype. This study has the potential to dispel concerns of lithium depletion and facilitate the sustainable development of lithium-based energy storage systems.

Uncovering fantastic synergistic lithium adsorption with manganese-titanium based composite nanospheres: Mild synthesis and molecular dynamics simulation insights

In light of the burgeoning energy technology sector and the ever-growing demand for lithium across diverse industrial domains, conventional lithium extraction methods have been proven inadequate due to their limited production capacity and high operational costs. This work introduces a novel approach to the manganese-titanium based composite HMTO (Mn:Ti=1:4) lithium ion-sieve (LIS) nanospheres, employing lithium acetate dihydrate, manganese carbonate and titanium dioxide P25 as the primary materials. These nanospheres exhibit relatively uniform spherical morphology, narrow size distribution, small average particle size (ca. 55 nm), large specific surface area (43.58 m2 g−1) and high surface O2− content (59.01%). When utilized as the adsorbents for Li+ ions, the HMTO (Mn:Ti=1:4) LIS demonstrates a fast adsorption rate, approaching equilibrium within 6.0 h with an equilibrium adsorption capacity (qe) of 79.5 mg g−1 and a maximum adsorption capacity (qm) of 87.26 mg g−1 (initial concentration C0: 1.8 g L−1). In addition, the HMTO (Mn:Ti=1:4) also delivers a high lithium extraction from the simulated high magnesium-lithium molar ratio salt lake brine (Mg:Li=103), achieving a qe of 33.85 mg g−1 along with a remarkable selectivity (αMgLi=2192.76). Particularly, the HMTO (Mn:Ti=1:4) LIS showcases a satisfactory recycling adsorption performance. The adsorption capacity remains at a high level, even that determined after the 5th cycle (55.45 mg g−1) surpasses that of the most recently reported adsorbents. Ultimately, the fantastic synergistic lithium adsorption mechanism is deliberately uncovered by leveraging the ion exchange principles and molecular dynamics (MD) simulations.

Hydrophilic surface-modified titanium-based lithium ion sieve adsorbents for efficient lithium extraction

Titanium-based lithium ion sieve adsorbents (HTOs) are considered among the most promising materials for lithium extraction from aqueous sources. In this study, four surfactants—sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), hydroxypropyl cellulose (HPC), and tannic acid (TA)—were used to surface-etch HTOs, preparing adsorbents with enhanced hydrophilicity at the nanoscale. Correlation studies between the hydrophilicity of the HTO-X and their adsorption performance revealed that all HTO-X had lower contact angles than the unetched counterparts, indicating improved adsorption capacities. Notably, TA plays a synergistic role of “killing two birds with one stone”. The TA-etched HTO-T adsorbent exhibited the lowest contact angle (8.8°) and the highest specific surface area (62.10 m2/g). In a LiCl solution, HTO-T’s adsorption capacity for Li+ reached 33.61 mg/g, a 26 % increase over the unetched HTO adsorbent (26.56 mg/g). Simultaneously, HTO-T significantly reduces the adsorption time and enhances the adsorption efficiency during the surface diffusion phase. Additionally, HTO-T demonstrated remarkable selectivity for lithium ions, with separation factors α(Li/Na), α(Li/K), α(Li/Mg), and α(Li/Ca) of 397.13, 181.55, 1288.47, and 1345.19, respectively, showcasing an excellent separation effect. The adsorption mechanism indicates that Li+ adsorption by HTO-T primarily occurs through the disruption of O–H bonds and the formation of new O-Li bonds. This research presents an efficient strategy for the development of HTOs, demonstrating HTO-T as a potential adsorbent for lithium recovery from brine sources.

Preparation of zirconium oxide surface-modified magnetic lithium-ion sieves and selectivity mechanism analysis for lithium extraction from salt-lake brine based on the first principle

The increasing need for lithium (Li) resources requires the creation of effective extraction methods. Lithium-ion sieves have shown promise as adsorption materials; however, their ultrafine powder properties and poor cycle performance limit their industrial application. In this study, a new lithium-ion sieve named ZrO2@HMFO, which consists of zirconium oxide-coated magnetic manganese (Mn), was investigated. The absorption and desorption of Li by ZrO2@HMFO in a LiCl solution were studied. The adsorption capacity of ZrO2@HMFO was 35.8 mg/g, and it led to a decrease in the dissolution of manganese (Mn) and iron (Fe) to 1.11 % and 0.49 %, respectively. The combination of metal cation doping and coating significantly reduces the dissolution loss of Mn. Density functional theory (DFT) was employed to analyze the mechanism of selective Li+ extraction. Analysis of hydration energy, migration energy barrier, and adsorption energy revealed that Li ions were the most selectively adsorbed. Additionally, the increase in selectivity was confirmed by calculating that Fe doping increases the energy required for other metal cations to replace Hydrogen ions (H+) or Lithium ions (Li+). Thus, ZrO2@HMFO allows for easy separation and stable circulation, making it a promising material for efficient Li+ separation in salt-lake brine. The study of the selectivity mechanism also provides theoretical guidance for improving the selectivity of lithium-ion sieves in future research.

Mxene-based lithium-ion sieve polymer membrane for sustainable lithium adsorption

Lithium, an emerging mineral of critical global significance, is recognized as a strategic resource by major economies worldwide, leading to an increased demand for this essential element. The extraction of lithium from rich sources, such as seawater and brine, has become commonplace. Among various liquid lithium extraction techniques, the lithium-ion sieve (LIS) adsorption method has attracted substantial attention owing to its simplicity, high recovery rate, and relatively low energy consumption. Despite significant advancements in LIS technology, the powdery nature of these materials poses challenges to handling and recycling, leading to inevitable adsorbent loss and limited practical applications. LISs are typically recycled through powder shaping, but the commonly employed shaping methods may result in a reduction in the adsorbent’s adsorption capacity. Therefore, it is urgent to develop a technology that can not only realize the recycling of LISs but also avoid the loss of the adsorbent’s adsorption capacity. We synthesized a titanium-based LIS (HTO) hybrid membrane by incorporating 2D MXene, known for its excellent properties across various applications. The incorporation of MXene into the membrane significantly increased the pore structure, enhancing adsorption site exposure and facilitating Li+ migration. The HTO/MXene@PVC hybrid film demonstrated favorable adsorption properties, with an Li+ adsorption capacity of 25.4 mg·g−1 within 24 h. Additionally, the film exhibited notable selectivity capacity and maintained its adsorption capacity above 90 % even after eight adsorption–desorption cycles, indicating excellent cycling performance. This study introduces a novel design concept for adsorbents, specifically for extracting Li+ from liquid lithium sources, offering new insights for the development of Li+ adsorbents aimed at enhancing lithium recovery.

Preparation of tungsten-doped Ti-based lithium ion sieves with excellent adsorption performance by hydrothermal method

Ti-based Li-ion sieve (H2TiO3, HTO), is attractive for adsorbing lithium from salt lakes. Nevertheless, the titanium dissolution and limited adsorption capacity affect the cycling stability and adsorption performance. In this work, an atom engineering technique was employed by doping tungsten (W) into layered HTO via a hydrothermal method. Through experiments and theoretical simulation, it was demonstrated that the doped W in HTO results in expanded interplanar spacing, increased surface adsorption energy, and excellent adsorption performance. The optimized HTO-W exhibits an Ti dissolution rate of 0.73 % (in 2 mol L−1 HCl for 12 h, 5.6 % that of pristine HTO) and adsorption capacity of 43.01 mg g−1 (in 425 mg L−1 LiCl solution at 30 °C, 1.4 times that of undoped HTO). Furthermore, the HTO-W reaches adsorption equilibrium in about 3 h with exceptional selectivity and stability. This work demonstrates an effective enhancement of lithium adsorption by W doping, providing new avenues for developing lithium adsorbents with high performance.

DFT calculation and experiments for Li+/H+ ion-exchange on titanium-based lithium ion-sieves

Titanium-based lithium ion-sieves (H2TiO3) with the layered structure is an excellent adsorbent for lithium recovery from brines, since it has a high theoretical Li+ ions adsorption amount (∼142 mg/g) and a stable structure under acid regeneration. However, the formation of the strong H–O bonds in H2TiO3 leads to a greater energy barrier for re-adsorption of lithium ions, so it would be difficult to reach the theoretical lithium adsorption capacity in practical application. Moreover, the influence of H+ content in brine (pH value) on the Li+ ion adsorption amount is obvious, that limits the lithium recovery efficiency from brines. In this work, Li+/H+ ion-exchange mechanism of layered H2TiO3 (HTO) ion-sieve is investigated through DFT calculation, where the Li+ ion adsorption energies for three kinds of Li+/H+ ion-exchange pathways are calculated, and the order of priority for Li+/H+ ion-exchange is deduced and validated based on the experimental data of Li+ ions adsorption on the prepared nanometer HTO ion-sieve. Then, a quantitative relationship between Li+ ion adsorption amounts on HTO ion-sieve and pH values in Li+-containing solution is developed on the basis of the experimental data. When the nanometer HTO ion-sieve powders are formed into the millimeter PVB-HTO ion-sieve granules for industrial application, it is found that the formation of an acidic micro-environment inside of this PVB-HTO granule obviously reduces the Li+ ions adsorption rate, especially in the initial stage of Li+/H+ ion-exchange process. Finally, an improved strategy of Li+/H+ ion-exchange rate on PVB-HTO granules from a carbonate-type brine is experimentally demonstrated utilizing a batch and a fixed-bed adsorber, respectively.

The role of CQDs in lithium ion sieve to recovery Li + from neutral salt lake brine

The demand for lithium and its compounds is increasing by years, but separating lithium ions from brines are challenging. A novel material of Peach gum Carbon Quantum dots (PG-CQDs) lithium ion sieve was prepared by using a simple precipitation method and heat treatment. The molecular formula of the adsorbent compound was H2.05Mn1.86C0.43O4 and the maximum adsorption capacity reached 34.6 mg/g, approximately twice that of the unmodified adsorbent, with a separation factor of 293.2–11434 in brine with a high Mg/Li ratio. Experimental and theoretical analyses indicated that he presence of Mn-O-C bonds in the adsorbent and that CQDs increase the pore structure of the lithium ion sieve and that the crystallisation of the original material changes, leading to an increase in BET surface area, proton number and adsorption capacity. The outstanding material can be massively used in lithium ions extraction in complex water system and carbon quantum dots doping Li+ sieve have potential application value for extracting lithium ions.

Phase transitions limit lithium adsorption in titanium-based ion sieves

Hydrogen titanium oxide (HTO) is a promising material in extracting lithium ions from dilute sources such as geothermal or oil/gas brines. However, experiments show limited Li adsorption in HTO compared to its theoretical maximum capacity, where all H atoms in HTO are replaced by Li that forms lithium titanium oxide (LTO). Here, ab initio molecular dynamics (AIMD) simulations show clear evidence of phase transitions at specific Li adsorption in pure or doped HTO/LTO, which directly predict their experimental maximum capacity. Analysis of thermodynamic properties as well as layered crystal structures show distinct Li-poor to Li-rich phase transitions in the pure, Mo-doped, and Fe-doped HTO/LTO. In addition, it is observed a second phase transition in the Fe-doped HTO/LTO in the Li-poor phases that further constrains Li adsorption. To the best of my knowledge, this is the first study that accurately predict the experimental capacities in ion sieves from first principle. More importantly, this study puts spotlights on phase transitions as an important consideration in molecular engineering developments of functional separation materials, such as the high-performance lithium-ion sieves presented herein.

Lithium recovery from Mexican geothermal brine via microwave-synthesized ion sieves

This paper investigates for the first time the feasibility of lithium recovery using lithium ion-sieves from a Mexican geothermal brine from a well of Cerro Prieto power plant. The materials were prepared following the microwave-assisted hydrothermal route to favor their sustainability. Also, the effect of the three manganese-based compounds as precursors was evaluated in which the vacancies were generated by acid treatment, by varying the acid concentration and the contact time. The structural characterizations showed that manganese sulfate was an efficient precursor for synthesizing LiMn2O4 spinel. The results of the uptake experiments, varying the pH of the Li solution showed that the highest sorption capacity is obtained at pH 12. The adsorption kinetics was better described by a pseudo second order equation (R2=0.9392). According to the Weber-Morris model, the process seems to be governed by film diffusion rather by intraparticle diffusion. The maximum adsorption capacity that was achieved was 9.64 mg/g and the thermodynamic equilibrium was best described by the Freundlich isotherm (R2=0.9769). Finally, the material was able to retain a competitive uptake capacity after five adsorption-desorption cycles.

Cu-doped titanium lithium-ion sieves with cell expansion and improved hydrophilicity for efficient extraction of lithium from aqueous resources

H2TiO3 (HTO) is one promising type of lithium-ion sieves (LISs) due to its theoretical adsorption capacity, stability and selectivity, but its actual adsorption ability is restricted. Since the larger radius of Cu ions than that of Ti4+, Cu doping was performed in this work for the purpose to improve adsorption performance by enlarging Li+ transport channels. The doping content of Cu as well its effect on structures, properties and adsorption performance of LISs were examined by various techniques. After trace doping of Cu, the hydrophilicity and specific surface area of HTO-Cu-0.04 (0.04 is the doping content) were improved, which can increase adsorption sites and accelerate Li+ diffusion process. And thus, HTO-Cu-0.04 owned enhanced adsorption capacity than HTO (35.58 vs 22.41 mg·g−1 at 298 K) and some other metal doped HTO in literature despite different adsorption conditions. The Li+ adsorption on HTO-Cu-0.04 is spontaneous and endothermic, following Langmuir isotherm model and pseudo-second-order kinetics model. The adsorption selectivity was examined in the simulated brine of Li+, Na+, K+, Ca2+, and Mg2+, which was analyzed by the distribution coefficient (Kd,Li) and separation factor (αMLi). After five adsorption–desorption cycles, the adsorption capacity of HTO-Cu-0.04 amounts to 95.8 % of the initial value, showing high stability. This work provides guidance for doping engineering to increase Li+ diffusion channels and hydrophilicity of LISs for improved Li+ recovery.