Recovery of Lithium Using Tributyl Phosphate in Methyl Isobutyl Ketone and FeCl3

Solvent extraction of lithium from brines with high magnesium/lithium ratios: investigation on parameter interactions

Solvent extraction of lithium from brine with a high Mg/Li ratio was investigated. Tributyl phosphate (TBP), ferric chloride (FeCl3), and kerosene were used as the extractant, co-extractant, and diluent, respectively. The mechanism of the extraction process was studied by LC-MS, UV-VIS, and FT-IR analyses. Effects of organic to aqueous phase volume ratio (O/A) on the extraction efficiency and separation factor were optimized. The effects of major parameters including Fe/Li molar ratio, hydrochloric acid concentration, and TBP volume percent as well as their interactions on the lithium extraction efficiency were evaluated using central composite design. These major parameters represent interactions within their selected ranges. While the lithium extraction efficiency as the response value in the experimental design showed the most sensitivity to the acid concentration, the separation factors were more affected by alteration in the TBP volume percent with the fixed optimum values of the other major parameters. The highest one-stage extraction efficiency of 76.3% and Li/Mg separation factor of 304 were obtained at the optimum conditions of Fe/Li = 2.99, HCl = 0.01 M, and TBP = 55%. The Mg/Li mass ratio could be significantly reduced from 192 in the feed to 1.5 in the stripping solution. Based on the findings, a schematic diagram of the process including extraction, stripping, and saponification steps was proposed.

Novel Fluorine-Pillared Metal-Organic Framework for Highly Effective Lithium Enrichment from Brine

The continuously developing lithium battery market makes seeking a reliable lithium supply a top priority for technology companies. Although metal-organic frameworks have been extensively researched as adsorbents owing to their exceptional properties, lithium adsorption has been scarcely investigated. Herein, we prepared a novel cuboid rod-shaped three-dimensional framework termed TJU-21 composed of fluorine-pillared coordination layers of Fe-O inorganic chains and benzene-1,3,5-tricarboxylate (BTC) linkages. Besides thermal and chemical robustness, a remarkably high lithium uptake of about 41 mg·g^-1 was observed on TJU-21 as a fast-spontaneous endothermic process. Single-crystal X-ray diffraction demonstrated that the adsorbed lithium was located in the cavity symmetrically assembled by iron sites and organic ligands between adjacent layers, while another kind of cavity in the framework circled by Fe-O-Fe-O-Fe-O-Fe chains and shared BTC linkages was occupied by hydrogen-bonded water molecules. Lithium adsorption resulted in decreased curviness of the coordination layers, and the binding energy change at O 1s as well as the increased Fe 2p peak, suggested potential interaction with iron sites. The practicability of TJU-21 as a lithium adsorbent was further proved by the considerable capacity and selectivity in simulated salt brines with excellent reusability.

Opposite selectivities of tri-n-butyl phosphate and Cyanex 923 in solvent extraction of lithium and magnesium

The synergic solvent extraction system of tri-n-butyl phosphate (TBP) and FeCl3 (or ionic liquids, ILs) has been extensively studied for selective extraction of Li from Mg-containing brines. However, Cyanex 923 (C923), which extracts many metals stronger than TBP, has not yet been examined for Li/Mg separation. Here, we report on the unexpected observation that the C923/FeCl3 system has opposite Li/Mg selectivity compared to the TBP/FeCl3 system. Detailed investigations show that the opposite selectivity of the C923/FeCl3 (or IL) system is due to three factors: (1) the strong extraction of Fe by C923 leads to a low concentration of [FeCl4]- in the system, which is essential for Li extraction; (2) C923 in combination with an IL extracts Mg strongly by an ion-pair mechanism; (3) most importantly, C923 extracts Mg by solvation, resulting in an insufficient concentration of C923 for Li extraction. The unexpected poor Li/Mg selectivity of C923 highlights the irreplaceable role of TBP in the selective recovery of Li.

Lithium recovery from salt-lake brine: Impact of competing cations, pretreatment and preconcentration

The global demand of lithium is rising steadily, and many industrially advanced countries may find it hard to secure an uninterrupted supply of lithium for meeting their manufacturing demands. Thus, innovative processes for lithium recovery from a wide range of natural reserves should be explored for meeting the future demands. In this study, a novel integrated approach was investigated by combining nanofiltration (NF), membrane distillation (MD) and precipitation processes for lithium recovery from salt-lake brines. Initially, the brine was filtered with an NF membrane for the separation of lithium ions (Li⁺) from competing ions such as Na⁺, K⁺, Ca²⁺ and Mg²⁺. The extent of permeation of metal ions by the NF membrane was governed by their hydrated ionic radii. Rejection by NF membrane was 42% for Li, 48% for Na and 61% for K, while both the divalent cations were effectively rejected (above 90%). Importantly, in the NF-permeate, Mg²⁺/Li⁺ mass ratio reduced to less than 6 (suggested for lithium recovery). The result showed that MD can enrich lithium with a concentration of 2.5 for raw brine and 5 for NF-treated brine. Following the enrichment of NF-permeate by the MD membrane, a two-stage precipitation method was used for the recovery of lithium. X-ray diffraction confirmed the precipitation of lithium as well as the formation of lithium carbonate crystals.

Effects of excessive lithium deintercalation on Li+ adsorption performance and structural stability of lithium/aluminum layered double hydroxides

Lithium/aluminum layered double hydroxides (Li/Al-LDHs) have been industrially proven to be recyclable lithium adsorbents that do not dissolve upon elution, although they are hypersensitive to lithium deintercalation. In this study, the Li⁺ adsorption performances and structural stabilities of Li/Al-LDHs samples with different lithium deintercalation intensities are comprehensively investigated and compared to expose the influence of excessive lithium deintercalation. The characterization results demonstrate that Li/Al-LDHs are inclined to transform to gibbsite under excessive lithium deintercalation. Moreover, this transformation is enhanced by a long deintercalation time at 80 °C in deionized water because the layered structure of Li/Al-LDHs collapses upon reduction of the lithium content. The Li⁺ adsorption kinetics and isotherms reveal that excessive lithium deintercalation has no effect on the adsorption pathway and rate, while the adsorption capacity fluctuates with increased lithium loss on account of the conflict between the generation of Li⁺ active sites and structural damage. Adsorption experiments at different pH values show that a neutral pH is more favorable because an acidic or alkaline condition leads to the undesirable formation of a gibbsite or amorphous phase in Li/Al-LDHs during adsorption. In addition, the presence of Mg²⁺ has a significant effect on the lithium adsorption capacity of Li/Al-LDHs. The adsorption capacities of Li/Al-LDHs samples with different lithium deintercalation intensities are all dramatically enhanced by a high Mg²⁺ concentration, reflecting the promising potential application of Li/Al-LDHs in Li⁺ extraction from low-grade brines with high Mg/Li ratios.

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.

Efficient Adsorption Performance of Lithium Ion onto Cellulose Microspheres with Sulfonic Acid Groups

The separation of Li+ from an aqueous solution has received much attention in recent years because of its wide application in batteries and nuclear energy. A cellulose microsphere adsorbent with sulfonic acid groups (named as CGS) was successfully prepared by the pre-irradiation-induced emulsion graft polymerization of glycidyl methacrylate onto cellulose microspheres through subsequent sulfonation and protonation. The adsorption performance of Li+ onto the CGS adsorbent is investigated in detail. The as-prepared CGS adsorbent exhibited fast adsorption kinetics and a high adsorption capacity of Li+ (16.0 mg/g) in a wide pH range from 4 to 10. The existence of K+ and Na+ was found to have the ability to affect the adsorption capacity of Li+ due to the cation-exchange adsorption mechanism, which was further confirmed by X-ray photoelectron spectroscopy (XPS). The column adsorption experiment indicated that the adsorption capacity of CGS agreed well with the batch adsorption, and a fast desorption could be obtained in 10 min. It is expected that CGS has potential usage in the adsorption separation of Li+ from an aqueous solution.

Effect of nickel ion doping in MnO2/reduced graphene oxide nanocomposites for lithium adsorption and recovery from aqueous media

Novel and effective reduced graphene oxide–nickel (Ni) doped manganese oxide (RGO/Ni-MnO₂) adsorbents were fabricated via a hydrothermal approach. The reduction of graphite to graphene oxide (GO), formation of α-MnO₂, and decoration of Ni-MnO₂ onto the surface of reduced graphene oxide (RGO) were independently carried out by a hydrothermal technique. The physical and morphological properties of the as-synthesized adsorbents were analyzed. Batch adsorption experiments were performed to identify the lithium uptake capacities of adsorbents. The optimized parameters for Li⁺ adsorption investigated were pH = 12, dose loading = 0.1 g, Li⁺ initial concentration = 50 mg L⁻¹, in 10 h at 25 °C. It is noticeable that the highest adsorption of Li⁺ at optimized parameters are in the following order: RGO/Ni3-MnO₂ (63 mg g⁻¹) > RGO/Ni2-MnO₂ (56 mg g⁻¹) > RGO/Ni1-MnO₂ (52 mg g⁻¹). A Kinetic study revealed that the experimental data were best designated pseudo-second order for each adsorbent. Li⁺ desorption experiments were performed using HCl as an extracting agent. Furthermore, all adsorbents exhibit efficient regeneration ability and to some extent satisfying selectivity for Li⁺ recovery. Briefly, it can be concluded that among the fabricated adsorbents, the RGO/Ni3-MnO₂ exhibited the greatest potential for Li⁺ uptake from aqueous solutions as compared to others.

Novel and effective reduced graphene oxide–nickel (Ni) doped manganese oxide (RGO/Ni-MnO₂) adsorbents were fabricated via a hydrothermal approach for lithium adsorption and recovery from aqueous media.

Lithium adsorption performance of a three-dimensional porous H2TiO3-type lithium ion-sieve in strong alkaline Bayer liquor

A three-dimensional porous H₂TiO₃-type lithium ion-sieve prepared by polystyrene colloidal microspheres template was applied to selectively adsorb Li⁺ ions from the strong alkaline Bayer liquor.