Ratio Brine Research Articles

A Nano‐Heterogeneous Membrane for Efficient Separation of Lithium from High Magnesium/Lithium Ratio Brine

AbstractLithium extraction from salt lake brines is highly demanded to circumvent the lithium supply shortage. However, polymer nanofiltration membranes suffer from low lithium permeability while nanofluidic devices are hindered by complicated preparation and miniaturized scales despite high permeability. Here, the authors report a facile strategy to prepare positively charged nanofiltration membranes for ultrapermeable and selective separation of lithium ions from concentrated magnesium/lithium mixtures. A new electrolyte monomer (diaminoethimidazole bromide, DAIB) containing bidentate amine groups is designed to modify pristine polyamide composite membranes. Structure characterizations and simulations show that the DAIB modification brings about nano‐heterogeneity that not only improves surface hydrophilicity, but also reduces water transport resistance through the ≈100 nm thick separation layer. Water permeance of the modified membrane improves fivefold and is coupled with good stability in 200‐h continuous nanofiltration. It exhibits high lithium flux (0.7 mol m−2 h−1) for brines (Mg2+/Li+ ratio 20) at 6 bar operation pressure.

Efficient Extraction of Lithium Ions from High Mg/Li Ratio Brine through the Synergy of TBP and Hydroxyl Functional Ionic Liquids

Summary of main observation and conclusionThe extraction of Li+ from the high Mg/Li ratio brine was performed using hydroxyl functional ionic liquids (ILs) as the coextractant and tributyl phosphate (TBP) as the extractant. Firstly, the extractive system, 1‐(2‐hydroxyethyl)‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([HOEmim][NTf2]) + TBP was proved to exhibit the highest extraction efficiency of Li+ (88.15%) from LiCl aqueous solutions among the extractants composed of different ILs, TBP, and ILs + TBP. Effects of various extraction parameters on the extraction efficiencies of Li+ and Mg2+ were then investigated. 95.01% of Li+ was extracted and the Li/Mg separation factor reached 405.76 in a single‐stage at 278.15 K and O/A of 2 : 1. The extraction complexes were determined by the slope analysis method and ESI‐MS analysis, and the metal complexes in the organic phase were indicated to be mainly [Li·2TBP][NTf2]. The striping study showed that 92.86% of Li+ was stripped with 1.0 mol·L–1 HCl. 98% extraction capacity of the synergy extractants was remained after 5 regeneration cycles. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°), together with the mechanism of the Li+ extraction were further demonstrated finally. According to the results, [HOEmim][NTf2] + TBP extraction system showed promising performance in extracting lithium from salt lake brine with high Mg/Li ratio.

Positively charged zwitterion-carbon nitride functionalized nanofiltration membranes with excellent separation performance of Mg2+/Li+ and good antifouling properties

A nanofiltration (NF) membrane with positive charges capable of separating Mg2+ and Li+ from high Mg/Li ratio brine was prepared by interfacial polymerization of 1, 4-bis (3-aminopropyl) piperazine (BAPP)/trimesoyl chloride monomers, and then nano graphitic carbon nitride (g-C3N4) functionalized with zwitterion (BHC-CN) was introduced into the active layer of the fabricated membrane. Salt permeation and selectivity were improved with the increase of BHC-CN content to 0.02% in BAPP solution. The morphology and surface chemical composition of BHC-CN were detected. The surface Zeta potential test indicates that the membrane fabricated with BHC-CN is positively charged at pH < 7.33. The presence of small aggregates on the surface of the membrane may increase the effective filtering area of the membrane and thus improve the permeability. It also exhibits long-time stability and excellent separation of Mg2+ and Li+, and the Mg/Li ratio is decreased from 73 in the feed to 1.85 in the permeation. Moreover, the resulted membrane shows good fouling resistance. In conclusion, the membrane has potential advantages in water softening and recovering Li+ from brine with high Mg/Li ratio.

Lithium recovery from ultrahigh Mg2+/Li+ ratio brine using a novel granulated Li/Al-LDHs adsorbent

A novel granulation method with high hydrophilia and considerable mechanical strength was developed for the lithium aluminum double hydroxides (Li/Al-LDHs) to recover lithium from old brines with ultrahigh Mg2+/Li+ ratios. The granulated Li/Al-LDHs (GLDH) displayed a great structure stability and Li+ adsorption capacity could reach up to 4.92 mg/g without weakening on the encapsulated Li/Al-LDHs at 303 K. The pore volume diffusion model (PVDM) based on adsorption isotherms was conducted to confirm that the Li+ adsorption process was controlled by the pore volume diffusion in GLDH. Besides, GLDH showed a great selectivity to Li+ with an ion selective sequence of Li+ > Na+ > K+≫Mg2+ > Ca2+, especially αMgLi could reach to 156.1. The column experiments declared that the adsorbed Li+ could be easily eluted by neutral Li+-containing solution and the Mg2+/Li+ ratio could decrease significantly from 301.58 in old brine to 0.99 in the strip solution. The working Li+ adsorption capacity of packed GLDH column exceeded 2.6 mg/g when Qarhan old brine was fed at a flow rate of 15 mL/min. Moreover, it was found that the strip solution with Li+ concentration less than 150 mg/L would cause the structure collapse of Li/Al-LDHs.

High-selective cyclic adsorption and magnetic recovery performance of magnetic lithium-aluminum layered double hydroxides (MLDHs) in extracting Li+ from ultrahigh Mg/Li ratio brines

The lithium-aluminum layered double hydroxides (Li/Al-LDHs) have been proved to be feasible to efficient lithium extraction from low-grade brines with ultrahigh Mg/Li ratios as Li+ adsorbents without elution damages. In this study, considering a sharp decline on the adsorption capacity resulting from the granulation in industrial applications, novel adsorbents, magnetic Li/Al layered double hydroxides (MLDHs), were synthesized via a simple staged coprecipitation method. The characterization and adsorption results proved doped Fe3O4 nanoparticles as magnetic cores were not harmful to the crystal phase and stability of the effective adsorption component Li/Al-LDHs in MLDHs. MLDHs exhibited favorable selective and preferential adsorption for Li+ in the Qarhan Salt Lake old brine with Mg/Li mass ratio of 284, whose adsorption capacity reached up to about 6.0 mg/g and Mg/Li ratios in desorption solution less than 0.4 with recovered Mg/Li ratios less than 6.0. By virtue of the superparamagnetism of Fe3O4 nanoparticles, a rapid recovery of MLDHs from brines after adsorption could be achieved easily using an external magnetic field. Furthermore, after 8 adsorption-desorption cycles, both the adsorption capacity and crystal structure of MLDHs had no significant change, indicating the great potential in the industrial lithium extraction from brines involving long-term recycling for adsorbents.

Separation of magnesium from high Mg/Li ratio brine by extraction with an organic system containing ionic liquid

The extraction of Mg2+ by di-(2-ethylhexyl) phosphoric acid (P204) was carried out to separate lithium and magnesium. To facilitate the direct electrodeposition of metallic magnesium from the magnesium-rich organic phase, different diluents and ionic liquids were investigated. It was found that tributylhexylphosphonium bis (trifluoromethyl sulfonyl) imide ionic liquid ([P4446][NTf2]) can serve as an excellent supporting electrolyte to solve the electroconductibility of the weak polarity organic phase. The electroconductivity was further increased by more than 1500 times by the use of methyl isobutyl ketone (MIBK) as a diluent. The single-stage extraction rate of Mg2+ at a concentration up to 76.87 g/L reached 68.4% using 40% P204 + 55% MIBK + 5% [P4446][NTf2] at R(O/A) = 6:1, and the electroconductivity of organic phase was 254.5 μS·cm−1 after extraction. The extraction mechanism and thermokinetics indicated that both [P4446][NTf2] and MIBK do not participate in the extraction process, and the extraction is an obvious endothermic process.

Selective separation of lithium from high Mg/Li ratio brine using single-stage and multi-stage selective electrodialysis processes

Lithium is an essential material in the energy and electronics industry. As abundant lithium resources, lake brines are exploited largely to extract lithium. Selective electrodialysis (S-ED) is a booming technology to recover and separate lithium from brines with high Mg/Li mass ratio. The effects of current, temperature and total dissolved solids (TDS) concentration of brine on the recovery rate of lithium, selective migration ratio, current efficiency and energy consumption were investigated by single-stage S-ED processes. The results confirm that a high current below limiting current density (LCD) could increase both the recovery rate of lithium and separation performance. Under a high temperature, the ion separation of lithium and magnesium decreases obviously but the recovery rate of lithium changes barely. Reducing TDS concentration has almost no effect on ion migration but increases energy consumption. Then according to the determination of LCD, a four-stage S-ED process with stepwise adjustment of current was conducted. The recovery rate of lithium could be obtained 90% with a decrease of Mg/Li mass ratio from 9.85 to 0.57.

Quantitative effects of Fe3O4 nanoparticle content on Li+ adsorption and magnetic recovery performances of magnetic lithium-aluminum layered double hydroxides in ultrahigh Mg/Li ratio brines

The quantitative effects of magnetic Fe3O4 nanoparticle content on Li+ adsorption and magnetic recovery performances of magnetic lithium-aluminum layered double hydroxides (MLDHs) were investigated systematically. MLDHs with different Fe3O4 nanoparticle contents were synthesized by a staged chemical coprecipitation method. The property disparities of these MLDHs were analyzed by various characterizations and results proved the existence of magnetic nanoparticles had no impairment on MLDHs crystal structure stability while the mesopores were lessened with the increasing Fe3O4 contents. In adsorption experiments using Qarhan Salt Lake brine with Mg/Li mass ratio of 284, the Li+ adsorption capacity of MLDHs presented a downtrend with the increasing Fe3O4, while the increased magnetic components had positive influence on the Li+ separation with Mg2+ on account of the steric effect. MLDHs presented excellent Li+ selectivity that the Mg/Li mass ratio of desorption solution was significantly decreased below 7.0. Relying on the superparamagnetism, MLDHs recovery all exceeded 97 % in the external magnetic field for only 10 min, and the magnetic recovery performance was promoted with more Fe3O4 nanoparticles. Furthermore, on the basis of experimental data, precise models were built and described well the correlations of Fe3O4 contents of MLDHs with Li+ adsorption capacity and magnetic recovery rate, respectively.

Negatively charged organic–inorganic hybrid silica nanofiltration membranes for lithium extraction

Abstract Effective extraction of lithium from high Mg2+/Li+ ratio brine lakes is of great challenge. In this work, organic–inorganic hybrid silica nanofiltration (NF) membranes were prepared by dip-coating a 1,2-bis(triethoxysilyl)ethane (BTESE)-derived separation layer on tubular TiO2 support, for efficient separation of LiCl and MgCl2 salt solutions. We found that the membrane calcinated at 400 °C (M1–400) could exhibit a narrow pore size distribution (0.63–1.66 nm) owing to the dehydroxylation and the thermal degradation of the organic bridge groups. All as-prepared membranes exhibited higher rejections to LiCl than to MgCl2, which was attributed to the negative charge of the membrane surfaces. The rejection for LiCl and MgCl2 followed the order: LiCl > MgCl2, revealing that Donnan exclusion effect dominated the salt rejection mechanism. In addition, the triple-coated membrane calcined at 400 °C (M3–400) exhibited a permeability of about 9.5 L ∙ m−2 ∙ h−1 ∙ bar−1 for LiCl or MgCl2 solutions, with rejections of 74.7% and 20.3% to LiCl and MgCl2, respectively, under the transmembrane pressure at 6 bar. Compared with the previous reported performance of NF membranes for Mg2+/Li+ separation, the overall performance of M3–400 is highly competitive. Therefore, this work may provide new insight into designing robust silica-based ceramic NF membranes with negative charge for efficient lithium extraction from salt lakes.

Highly selective lithium recovery from high Mg/Li ratio brines

Here, we report a new liquid-membrane electrodialysis capable of selectively recovering lithium from high Mg/Li ratio brines. The liquid membrane is composed of an ionic liquid system as the Li+ carrier that presents high selectivity toward Li+ and long-term sustainability, and 2 solid cation-exchange membranes to sandwich the carrier. Recognition and selective electromigration of Li+ can be achieved by the sandwiched liquid membrane assisted by an electric field. The Mg/Li decreases from 50:1 in the initial feeding brine to 0.5:1 in the receiving solution after electrodialysis at a current density of 4.375 A·m−2 for 12 h. Moreover, higher current efficiency (65%) and lower specific energy consumption (16 Wh·g−1 Li) are obtained compared to typical electrodialysis processes. From the perspective of practical application, the Mg/Li drops to 0.26:1 from 53:1 in the old brine from West Taijinair, and K+ and Ca2+ in the brine are almost completely blocked by the liquid membrane. This method displays a great perspective on the application for lithium recovery from high Mg/Li brines owing to its high selectivity, efficient energy utilization, and environmental friendliness.

A novel precipitant for separating lithium from magnesium in high Mg/Li ratio brine

In the current study, a novel precipitant, sodium metasilicate nonahydrate, was investigated as a new magnesium precipitant for separating lithium from magnesium in brine with a high Mg/Li mass ratio. Various parameters and relative mechanisms of the precipitation process such as reaction time, agitation rate, sodium metasilicate nonahydrate dosage, and aging time were systematically studied. Sodium metasilicate nonahydrate exhibited superior performance in terms of precipitating magnesium and separating lithium from magnesium in brines with large ranges of initial Li+ and Mg2+ concentrations. It is demonstrated that appropriate agitation rate and aging time were beneficial for magnesium precipitation and enhancing the filtration capacity of the precipitates. The Li+ recovery in solution, Mg2+ precipitation rate, and mass ratio of Mg/Li reached approximately 86.73%, 99.94%, and 0.022, respectively, starting from an initial Mg/Li mass ratio of 30. The encouraging results suggest that Li can be recovered to a substantial degree from brines of different compositions via a precipitation method employing sodium metasilicate nonahydrate as the precipitant for Mg.

Numerical simulation of continuous extraction of highly concentrated Li+ from high Mg2+/Li+ ratio brines in an ion concentration polarization-based microfluidic system

New technologies for efficient ion separation (e.g. extraction of lithium from salt lake brines) are highly desirable due to industrial and environmental concerns. A new ion concentration polarization (ICP)-based ion separation system, which is capable of extracting concentrated Li+ solutions continuously from high Mg2+/Li+ ratio brines is proposed. This system uses ICP-induced amplification of the electric field to concentrate Li+ ions and expel Mg2+, with external pressures applied to modulate the feeding flow of the brine in the microchannel and the bifurcated flow of concentrated Li+ through the branch. Through numerical simulations using a simplified two-dimensional model, effects of key operational parameters as well as same structural parameters are elaborated. It is demonstrated that the proposed system is able to continuously extract ∼38% of Li+ from the raw brine at a fluid flow velocity of ∼1 mm/s. The concentration of Li+ in the product solution is about ∼13 times of the raw brine, with a Li+/Mg2+ mass ratio of ∼10 (∼600 times of the raw brine). This work provides clear fundamental mechanism underlying the new method, offers important guidance for the design of relevant experiments, and paves the way for the potential industrialization of high efficiency Li+ extraction technologies.

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.

Effect of coexisting ions on recovering lithium from high Mg2+/Li+ ratio brines by selective-electrodialysis

Abstract Selective-electrodialysis (S-ED) is a booming technology for recovering lithium from salt lake brine and (concentrated) seawater, especially from high Mg2+/Li+ ratio brines. The coexisting ions in the solutions containing lithium can make some impact on the ion fractionation of lithium and magnesium in high Mg2+/Li+ brines. The effect of the concentration of coexisting cations (Na+, K+) and anions (SO42−, HCO3−) on the separation coefficient of magnesium and lithium (FMg-Li), recovery ratio of Li+ (RLi), current efficiency (η) and specific energy consumption (ESEC) was evaluated. The results show that an applied voltage of 6 V is more preferable for lithium ions recovery from high Mg2+/Li+ brines by S-ED. The separation of Mg2+/Li+ tends to unsatisfactory with increasing cation concentration (Na+, K+), and FMg-Li drops from 8.73 to 1.83 with the increase of Na+/Li+ from 1 to 5 and from 8.33 to 2.13 with the rise of K+/Li+ from 1 to 5. The strength of influence on the separation of Mg2+/Li+ is K+ > Na+, correlating with the order of their hydrated ion radiuses. However, FMg-Li rises from 7.99 to 14.66 with the increase of SO42−, reversing with the influence of cations concentration. As for HCO3−, the variation tendency of FMg-Li is opposite to RLi, probably ascribing to the appearance of MgHCO3+. These observations showed that S-ED has a wide adaptability for the ion fractionation of magnesium and lithium from brines.

Direct numerical simulation of continuous lithium extraction from high Mg2+/Li+ ratio brines using microfluidic channels with ion concentration polarization

A novel ion concentration polarization-based microfluidic device is proposed for continuous extraction of Li+ from high Mg2+/Li+ ratio brines. With simultaneous application of the cross-channel voltage that drives electroosmotic flow and the cross-membrane voltage that induces ion depletion, Li+ is concentrated much more significantly than other cations in front of the membrane in the microchannel. The application of external pressure produces a fluid flow that drags a portion of Li+ (and Na+) to flow through the microchannel, while keeping most of Mg2+ (and K+) blocked, thus implementing continuous Li+ extraction. Two-dimensional numerical simulation using a microchannel of 120 µm length and 4 µm height and a model, highly concentrated brine, shows that the system may produce a continuous flow rate of 1.72 mm/s, extracting 25.6% of Li+, with a Li+/Mg2+ flux ratio of 2.81 × 103, at an external pressure of 100 Pa and cross-membrane voltage of 100 times of thermal voltages (25.8 mV). Fundamental mechanisms of the system are elaborated and effects of the cross-membrane voltage and the external pressure are analyzed. These results and findings provide clear guidance for the understanding and designing of microfluidic devices not only for Li+ extraction, but also for other ionic or molecular separations.

New Insights into the Application of Lithium-Ion Battery Materials: Selective Extraction of Lithium from Brines via a Rocking-Chair Lithium-Ion Battery System.

Lithium extraction from high Mg/Li ratio brine is a key technical problem in the world. Based on the principle of rocking‐chair lithium‐ion batteries, cathode material LiFePO4 is applied to extract lithium from brine, and a novel lithium‐ion battery system of LiFePO4 | NaCl solution | anion‐exchange membrane | brine | FePO4 is constructed. In this method, Li+ is selectively absorbed from the brine by FePO4 (Li+ + e + FePO4 = LiFePO4); meanwhile, Li+ is desorbed from LiFePO4 (LiFePO4 − e = Li+ + FePO4) and enriched efficiently. To treat a raw brine solution, the Mg/Li ratio decreases from the initial 134.4 in the brine to 1.2 in the obtained anolyte and 83% lithium is extracted. For the treatment of an old brine solution, the Mg/Li ratio decreases from the initial 48.4 in the brine to 0.5 and the concentration of lithium in the anolyte is accumulated about six times (from the initial 0.51 g L−1 in the brine to 3.2 g L−1 in the anolyte), with the absorption capacity of about 25 mg (Li) g (LiFePO4)−1. Additionally, it displays a great perspective on the application in light of its high selectively, good cycling performance, effective lithium enrichment, environmental friendliness, low cost, and avoidance of poisonous organic reagents and harmful acid or oxidant.

Separating lithium and magnesium in brine by aluminum-based materials

Separating lithium and magnesium from high Mg/Li mass ratio brine is an internationally recognized concern. The following study used the reaction between the aluminum-based material with the brine in order to investigate the reaction process of the lithium precipitation as well as the influences on the lithium precipitation rate and Mg/Li mass ratio in precipitation. The results showed that the direct reaction process of the aluminum-based material with the brine helped to eliminate the product coating on the surface of the raw material while enhancing the lithium precipitation rate. Aluminum-based materials exhibit the excellent performance of precipitating lithium and separating lithium and magnesium. The lithium precipitation rate reached 78.3%. The Mg/Li mass ratio in the precipitate was only 0.02, under the optimal conditions. The results were informative for the separation of lithium and magnesium in a salt lake brine.

Recovery of both magnesium and lithium from high Mg/Li ratio brines using a novel process

In this study, an integrated process was developed to separate and simultaneously recover both magnesium and lithium from brines. This technology includes production of magnesium-aluminum-carbonate-layered double hydroxide materials (MgAlCO3-LDHs), removal of boron, CO32–, and SO42−, and precipitation of lithium carbonate. Factors such as water addition ratio, Mg2+/Al3+ mole ratio, and lithium loss rate were investigated during MgAlCO3-LDHs production. The effects of lithium concentration and CO32−/2Li+ mole ratio on lithium carbonate precipitation were also studied. It was found magnesium and lithium had been effectively separated after MgAlCO3-LDHs production. The magnesium content in brine displayed a notable decrease from 117g/L to less than 0.02g/L with a lithium yield more than 95.0%. To concentrate lithium and precipitate lithium carbonate, 96.46% of boron, 99.2% of the CO32−, and 99.56% of the SO42− impurities were removed from the brine by adsorption, acidification, and precipitation, respectively. The lithium yield was more than 91% when lithium concentration in brine approximated 27g/L and the CO32−/2Li+ mole ratio was 1.2. The purity of this product was 99.70%. Overall, this study provides an interesting vision for future integrated utilization of magnesium and lithium resources from salt lake brines with high Mg/Li ratio.

Lithium Enrichment of High Mg/Li Ratio Brine by Precipitation of Magnesium via Combined CO2 Mineralization and Solvent Extraction

A new method coupling CO2 mineralization and solvent extraction was proposed and investigated to precipitate magnesium from high Mg/Li ratio brine. Organic amine was employed to extract HCl formed during the CO2 mineralization process and to realize continuous conversion of MgCl2 to precipitated MgCO3, thereby removing the magnesium contained in the brine. The effects of brine concentration, extractant, diluents, extractant concentration, phase ratio, and reaction temperature were systematically investigated. A blend of trioctylamine and isoamyl alcohol was used as the extractant and diluent, and the reaction parameters were optimized. The mechanism was proposed, and a stripping process was designed. Under the optimal conditions, the conversion of magnesium was as high as 67.41%, and the Mg/Li ratio of the raffinate decreased from 20 to 5.4.

Preliminary study on recovering lithium from high Mg2+/Li+ ratio brines by electrodialysis

Abstract An electrodialysis (ED) system equipped with monovalent selective permeability ion exchange membrane was used to investigate the separation of magnesium and lithium in salt lake brines. Some objective functions including separation coefficient of magnesium and lithium (FMg Li), recovery ratio of lithium (RLi) and current efficiency (η), were applied to explore the effect of the applied voltage, the linear flow velocities, the Mg2+/Li+ ratio and pH on the process of extracting lithium. The results showed that the increase of applied voltage could improve the separation coefficient and the recovery ratio of lithium, but energy consumption would also rise; with the increase of feed linear velocity, the separation coefficient had a rising trend, but too large linear velocity would lead to increasing energy consumption and reducing current efficiency. When the Mg2+/Li+ ratio was in the range of 5–92, ED technology showed higher separation efficiency. Linear flow velocities of concentrating and desalting compartments (1.9–7.6 cm/s) showed positive correlation with the migration of the ions. According to the comprehensive analysis of the experimental results, the optimal operation conditions of the ED device are as follows: the applied voltage (5 V), concentration of electrolyte solution (5 wt% Na2SO4) and the linear velocities of desalting/concentrating/electrolyte (6.2, 6.2 and 3.8 cm/s). When the brine with Mg2+/Li+ ratio of 60 was treated by the ED for 2 h under this condition, the separation coefficient was 12.48. And the recovery ratio of Li+, current efficiency and the Mg2+/Li+ ratio of concentrate was 72.46 wt%, 8.68 wt% and 7, respectively. The concentrate, which could be considered as a bittern with lower Mg2+/Li+ ratio (