Methods and systems for selective extraction of lithium from brines using thermoresponsive solvents

Abstract

Thermoresponsive, switchable-hydrophilicity amine solvents such as diisopropylamine (DIPA), N,N-dimethylcyclohexylamine (DMCHA), dipropylamine (DPA), N-ethylcyclohexylamine (ECHA), triethylamine (TEA), and tert-octylamine (TOA) are used to extract lithium from hypersaline brines. The solvent is mixed with hypersaline brines containing lithium and other alkali metal cations at an extraction temperature. The result is a multi-phase mixture including a light, organic extract phase above a heavy, aqueous raffinate phase. Water and salt partitions from the aqueous phase into the organic phase, and lithium is preferentially partitioned over other alkali metal cations, enabling ion-specific separation. The extract is separated from the raffinate and warmed to a disengagement temperature. At higher temperatures, phase disengagement occurs as the substantially all previously extracted ions and water demix from the organic phase, yielding an aqueous product water stream containing the extracted cations and enriched with lithium. The regenerated solvent can be recycled for use in treatment of additional feed brine.

Description

METHODS AND SYSTEMS FOR SELECTIVE EXTRACTION OF LITHIUM FROM BRINES USING THERMORESPONSIVE SOLVENTSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application Nos. 63 / 650,525, filed May 22, 2024, 63 / 804,277, filed May 12, 2025, and 63 / 810,185, filed May 22, 2025, which are incorporated by reference as if disclosed herein in their entireties.BACKGROUND

[0002] Lithium is utilized for energy storage and is beneficial for the clean energy transition. Global lithium demand is projected to reach 1.2-1.7 million tons by 2050, a 7-10 times increase from 2023. Bridging this supply gap will include scaling production from conventional sources, unlocking technologically inaccessible lithium assets, leveraging secondary stocks through recycling and reuse, etc. With more than 60% of global lithium reserves, continental brines, e.g., the Lithium Triangle salars of Chile, Argentina, and Bolivia, are poised to play an increasing role in lithium production over pegmatite hard rock deposits and hydrothermally-altered clay, especially as ore grades rapidly decline and concerns grow over the environmental toll of hard rock mining. At the same time, lithium extraction from unutilized sources, such as geothermal and oilfield brines, is gaining attention. Tapping into these alternative resources offers opportunities to build capacity and mitigate supply risks by expanding the geographic diversity of lithium.

[0003] However, technical barriers currently hinder access to lithium in these unconventional brines: primarily, the low Li+concentrations and the high levels of competing cations. Natural evaporation, the prevailing practice in conventional lithium production operations, is not viable for concentrating unconventional brines as Li+levels are well below 500 mg / L. These conventional methods are also time-consuming, water-intensive, and restricted to arid regions with abundant, inexpensive land. The presence of other cations at greater abundance in the brine can lead to co-precipitation during lithium carbonate processing, compromising product purity and necessitating extensive posttreatment. Similar problems also affect aqueous-phase lithium recycling approaches.

[0004] Developing technologies to overcome the aforementioned technical barriers can unlock dormant lithium assets. A suite of emerging techniques, collectively designated direct lithium extraction (DLE) technologies, seeks to do so by selectively separating lithium fromother ionic species and solutes, e.g., without evaporation. The current status, prospects, and challenges of DLE have been evaluated. Leading examples include sorption, solvent extraction, membrane filtration, and electrochemical processes. Each DLE method holds advantages and promise while also having specific drawbacks and limitations. Further, separating lithium from other monovalent cations remains a hurdle for many existing DLE technologies.

[0005] What is desired, therefore, are effective systems and processes for the selective recovery of lithium from brines containing elevated concentrations of alkali metals such as sodium and potassium.SUMMARY

[0006] Aspects of the present disclosure are directed to selectively extracting lithium from brine streams containing sodium and potassium. In some embodiments, a solvent with a thermoresponsive affinity for salt and water is combined with a brine containing lithium and other alkali metal cations at an extraction temperature. During the subsequent extraction, ions along with water can partition into the switchable solvent. Although the solvent is present in its more hydrophilic state at the extraction temperature, it is only partially miscible with water, so the result is a multi-phase mixture including aqueous and organic phases. Lithium is preferentially extracted over other alkali metal cations, enabling ion-specific separation. Upon gravitational settling at the extraction temperature, two distinct liquid layers form, with the light, organic phase above the heavy, aqueous phase, i.e., extract and raffinate, respectively. The extract can then be physically separated from the raffinate and warmed to a disengagement temperature. At higher temperatures, the thermoresponsive solvent is switched to become more hydrophobic, thereby lowering the solubility limit for salt and water. Consequently, phase disengagement occurs as the previously extracted ions and water demix from the organic phase, yielding an aqueous product stream and a regenerated solvent stream. The product stream contains the extracted ions and is enriched in lithium. The regenerated solvent can be cooled and cycled back into the process for reuse, e.g., contacted with additional feed brine. Effectively, all cations extracted into the organic phase at the extraction temperature are released into the aqueous product at the disengagement temperature, i.e., the extract is a valid proxy for selectivity because cation concentrations are practically identical in the extract and product streams.

[0007] Aspects of the present disclosure are directed to a method of recovering a lithium product from brines. In some embodiments, the method includes mixing one or more brines with one or more switchable-hydrophilicity solvents to form a multi-phase mixture, the brines including a concentration of lithium cations (Li+) and a concentration of non-Li cations;equilibrating the multi-phase mixture at a first temperature including an organic-rich phase and an aqueous phase; separating at least a portion of the organic-rich phase from the multi-phase mixture at the first temperature to form a separated portion; heating the separated portion to a second temperature to form a solvent product and a product water, wherein the product water has an elevated concentration of Li+relative to the solvent product, and recovering at least a portion of the product water. In some embodiments, the method includes collecting at least a portion of the aqueous phase to form a raffinate portion and contacting the raffinate portion with at least a portion of the solvent product to form an additional multi-phase mixture. In some embodiments, heating the separated portion to a second temperature to form a solvent product and a product water includes heating the separated portion to an intermediate temperature prior to heating the separated portion to the second temperature, and recovering an intermediate product water from the separated portion at the intermediate temperature, wherein the intermediate temperature is between the first temperature and the second temperature.

[0008] In some embodiments, the total cation concentration in one or more brines is above about 3.5 mol / L. In some embodiments, the ratio of concentration of Li+to the concentration of non-Li cations ([Li+] / [M+]) in the one or more brines is below about 1 : 1. In some embodiments, the [Li+] / [M+] in the one or more brines is below about 1 : 100. In some embodiments, the first temperature is below about 40°C. In some embodiments, the second temperature is above about 60°C. In some embodiments, the brine includes geothermal brines, oilfield brines, salt-lake brines, LiCl, NaCl, KC1, or combinations thereof. In some embodiments, the switchable-hydrophilicity solvent includes diisopropylamine (DIP A), N,N- dimethylcyclohexylamine (DMCHA), dipropylamine (DPA), N-ethylcyclohexylamine (ECHA), triethylamine (TEA), tert-octylamine (TOA), diethylamine, ethylpropylamine, N,N- di ethylmethylamine, methylbutylamine, 1- methylbutylamine, 1 -ethylpropylamine, diallylamine, cyclohexylamine, N-ethylmethylallylamine, hexamethyleneimine, 1 -methylpiperidine, 2- m ethylpiperidine, 3 -methylpiperidine, 4-methylpiperidine, butyldimethylamine, tertbutyldimethylamine, ethylbutylamine, tert-butylethylamine, hexylamine, 2,6-dimethylpiperidine, 3,3-dimethylpiperidine, 3,5-dimethylpiperidine, N-methylcyclohexylamine, 2- methylcyclohexylamine, heptylamine, N-methyl-l,3-dimethylbutylamine; 1 -methylhexylamine, 1 -ethylpiperidine, 2-ethylpiperidine, dibutylamine, diisobutylamine, di-sec-butylamine, N,N- diisopropylethylamine, 1,5-dimethylhexylamine, 2-ethylhexylamine, octylamine, 1- propylpiperidine, triallylamine, N-isopropylcyclohexylamine, 3,3,5-trimethylcyclohexylamine, 1 -methyloctylamine, tripropylamine, tert-butylcyclohexylamine, di ethylcyclohexylamine, decylamine, dimethyloctylamine, dipentyl amine, dibutylethylenediamine, N,N,N',N'-tetramethyl-l,6-hexanediamine, 1 -methyldecylamine, dihexylamine, dodecylamine, tributylamine, triisobutylamine, C4H11N, C5H13N, CeHnN, CeHoN, CeHisN, C7H15N, C7H17N, C7H19N, QH17N, C8HI9N, C8H2IN, C9H15N, C9H19N, C9H21N, C10H21N, C10H23N, C10H24N2, C11H25N, C11H26N2, C12H27N, or combinations thereof. In some embodiments, the multi-phase mixture further comprises one or more anionic components, wherein the anionic components include iodine anions (I’), bromine anions (Br ), or combinations thereof. In some embodiments, the concentration of some anionic components is less than the concentration of Li+. In some embodiments, the ratio of some anionic components to chloride is varied between pure chloride, [X'] / [C1‘] = about 1 :3, [X'] / [C1‘] = about 1 : 1, [X'] / [C1‘] = about 3: 1, and pure anionic component. In some embodiments, the intermediate temperature is between about 20°C and about 55°C. In some embodiments, the product water has a concentration of Li+above about 25 g / L.

[0009] Aspects of the present disclosure are directed to a method of recovering a lithium product from brines preparing a multi-phase mixture, the multi-phase mixture including one or more brines including a concentration of Li+and a concentration of non-Li cations; and one or more switchable-hydrophilicity solvents; equilibrating the multi-phase mixture at a first temperature including an organic-rich phase and an aqueous phase; separating at least a portion of the organic-rich phase from the multi-phase mixture at the first temperature to form a separated portion; heating the separated portion to an intermediate temperature; recovering an intermediate product water from the separated portion at the intermediate temperature; heating the separated portion to a second temperature to form a solvent product and a product water, wherein the product water has an elevated concentration of Li+relative to the solvent product and the intermediate temperature is between the first temperature and the second temperature, recovering at least a portion of the product water, collecting at least a portion of the aqueous phase to form a raffinate portion, and contacting the raffinate portion with at least a portion of the solvent product to form an additional multi-phase mixture.

[0010] Aspects of the present disclosure are directed to a method of treating brines includes preparing a multi-phase mixture, the multi-phase mixture including one or more brines including a concentration of Li+and a concentration of non-Li cations, one or more switchable- hydrophilicity solvents, and one or more anionic components; equilibrating the multi-phase mixture at a first temperature including an organic-rich phase and an aqueous phase; separating at least a portion of the organic-rich phase from the multi-phase mixture at the first temperature to form a separated portion; heating the separated portion to a second temperature to form a solvent product and a product water, wherein the product water has an elevated concentrationof Li+relative to the solvent product; recovering at least a portion of the product water, and recycling at least a portion of the solvent product to the multi-phase mixture.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings show embodiments of the disclosed subject matter for the purpose of illustrating the invention. However, it should be understood that the present application is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:

[0012] FIG. l is a chart of a method of recovering a lithium product from brines according to some embodiments of the present disclosure;

[0013] FIG. 2 is a chart of a method of treating brines according to some embodiments of the present disclosure;

[0014] FIG. 3 A is a graph showing mole balance data for lithium and sodium ions (filled and empty columns, respectively) in process streams of systems and methods of recovering a lithium product from brines according to some embodiments of the present disclosure, using tertoctylamine (TOA) as a switchable amine solvent;

[0015] FIG. 3B is a graph showing the selectivity for lithium over sodium in the product stream relative to the feed brine and extraction capacity for six switchable amine solvents according to some embodiments of the present disclosure;

[0016] FIG. 4 is a graph showing the mass fraction of lithium recovered in product water relative to the mass fraction of lithium in feed brine using systems and methods according to some embodiments of the present disclosure;

[0017] FIG. 5A is a graph showing selectivity for cations in an organic phase relative to binary salt mixture feed brines using systems and methods according to some embodiments of the present disclosure;

[0018] FIG. 5B is a graph showing selectivity for cations in an organic phase relative to a simulated Salton Sea post-flash geothermal brine using systems and methods according to some embodiments of the present disclosure;

[0019] FIG. 6A is a graph showing lithium yields and selectivity for semi-batch embodiments for extracting lithium from brines using TOA;

[0020] FIG. 6B is a graph showing lithium yields and selectivity for semi-batch embodiments for extracting lithium from brines using dipropylamine (DPA);

[0021] FIG. 7A is a graph showing the relationship between feed brine concentration and lithium selectivity using various solvents according to some embodiments of the present disclosure;

[0022] FIG. 7B is a graph showing the relationship between feed brine concentration and lithium selectivity at various temperatures using solvents according to some embodiments of the present disclosure;

[0023] FIG. 7C is a graph showing the relationship between lithiunrwater selectivity and lithium: sodium selectivity at various temperatures using TOA according to some embodiments of the present disclosure;

[0024] FIGs. 8A-8B are graphs demonstrating lithium selectivity and lithium extraction capacity in the presence of anionic components such as bromine using DPA according to some embodiments of the present disclosure;

[0025] FIG. 8C is a graph demonstrating lithium yield and selectivity in the presence of anionic components such as iodine using TOA according to some embodiments of the present disclosure; and

[0026] FIG. 9 is a schematic representation of a system of recovering a lithium product from a feedstream according to some embodiments of the present disclosure.DETAILED DESCRIPTION

[0027] Referring now to FIG. 1, some embodiments of the present disclosure are directed to a method 100 of recovering a lithium product from brines. In some embodiments, at 102, one or more brines are mixed with one or more switchability-hydrophilicity solvents. In some embodiments, the brines include a concentration of lithium cations (Li+). In some embodiments, the brines include a concentration of Li+and a concentration of non-Li+cations. In some embodiments, the brines include a concentration of Li+and a concentration of non-Li+alkali metal cations. In some embodiments, the brines include a concentration of Li+and a concentration of sodium cations (Na+), potassium cation (K+), or combinations thereof. In some embodiments, the brines include geothermal brines, oilfield brines, salt-lake brines, LiCl, NaCl, KC1, or combinations thereof. In some embodiments, the total cation concentration in one ormore brines is above about 0.5, 1, 1.5, 2, 2.5, 3, etc. mol / L. In some embodiments, the total cation concentration in the one or more brines is above about 3.5 mol / L, enabling recovery of product water from the brines with increased Li+concentration relative to the brines themselves, as will be discussed in greater detail below. In some embodiments, the ratio of concentration of Li+to the concentration of non-Li cations ([Li+] / [M+]) in the one or more brines is below about 100: 1. In some embodiments, the [Li+] / [M+] in the one or more brines is below about 10:1. In some embodiments, the [Li+] / [M+] in the one or more brines is below about 1 : 1. In some embodiments, the [Li+] / [M+] in the one or more brines is below about 1 :10. In some embodiments, the [Li+] / [M+] in the one or more brines is below about 1 : 100. In some embodiments, the [Li+] / [M+] in the one or more brines is about 1 : 1000.

[0028] In some embodiments, the hydrophilicity of the solvents is thermoresponsive. In some embodiments, the solvent is basic. In some embodiments, the solvent includes one or more hydrophilic moieties in a mainly hydrophobic structure. In some embodiments, the solvent is an amine solvent, e.g., a primary, secondary, or tertiary amine solvent. In some embodiments, the solvent includes diisopropylamine (DIP A), N,N-dimethylcyclohexylamine (DMCHA), dipropylamine (DPA), N-ethylcyclohexylamine (ECHA), triethylamine (TEA), tert-octylamine (TO A), di ethylamine, ethylpropylamine, N,N-di ethylmethylamine, methylbutylamine, 1- m ethylbutylamine, 1 -ethylpropylamine, diallylamine, cyclohexylamine, N- ethylmethylallylamine, hexamethyleneimine, 1 -methylpiperidine, 2-m ethylpiperidine, 3- methylpiperidine, 4-methylpiperidine, butyldimethylamine, tert-butyldimethylamine, ethylbutylamine, tert-butylethylamine, hexylamine, 2,6-dimethylpiperidine, 3,3- dimethylpiperidine, 3,5-dimethylpiperidine, N-methylcyclohexylamine, 2- methylcyclohexylamine, heptylamine, N-methyl-l,3-dimethylbutylamine; 1 -methylhexylamine, 1 -ethylpiperidine, 2-ethylpiperidine, dibutylamine, diisobutylamine, di-sec-butylamine, N,N- diisopropylethylamine, 1,5-dimethylhexylamine, 2-ethylhexylamine, octylamine, 1- propylpiperidine, triallylamine, N-isopropylcyclohexylamine, 3,3,5-trimethylcyclohexylamine, 1 -methyloctylamine, tripropylamine, tert-butylcyclohexylamine, di ethylcyclohexylamine, decylamine, dimethyloctylamine, dipentyl amine, dibutylethylenediamine, N,N,N',N'- tetramethyl-l,6-hexanediamine, 1 -methyldecylamine, dihexylamine, dodecylamine, tributylamine, triisobutylamine, C4H11N, C5H13N, CeHnN, CeHoN, CeHisN, C7H15N, C7H17N, C7H19N, QH17N, C8HI9N, C8H2IN, C9H15N, C9H19N, C9H21N, C10H21N, C10H23N, C10H24N2, C11H25N, C11H26N2, C12H27N, or combinations thereof.

[0029] In some embodiments, mixing 102 the brine(s) with switchable-hydrophilicity solvent(s) forms a multi-phase mixture. In some embodiments, the multi-phase mixture isfurther mixed with one or more anionic components. In some embodiments, the concentration of the anionic components in the multi-phase mixture is less than the concentration of Lit In some embodiments, the anionic components include iodine anions (L), bromine anions (Br ), or combinations thereof. In some embodiments, the anionic components include Nal, NaBr, or combinations thereof.

[0030] Still referring to FIG. 1, in some embodiments, at 104, the multi-phase mixture is equilibrated at a first temperature (TL). In some embodiments, TL is below about 40°C. In some embodiments, TL is between about 5°C and about 40°C. In some embodiments, TL is about 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, or 40°C. In some embodiments, the equilibrated multi-phase mixture includes an organic-rich phase and an aqueous phase. In some embodiments, at temperature TL, at least some of the water in the aqueous phase, i.e., from the brines, partitions into the organic-rich phase. In some embodiments, cations present in the aqueous phase partition with the water into the organic rich phase. Advantageously, Li+is preferentially extracted into the organic-rich phase over other cations, even other alkali metal cations such as Na+and K+. Li+has a higher charge density and lower polarizability than other alkali metal cations, i.e., is a harder acid according to the Hard-Soft Acid-Base theory, and as such the intermolecular attraction forces around Li+, including between solvating species, are stronger. Salt ions are extracted into the low-dielectric organic-rich phase through association with H2O molecules. Li+outcompetes Na+, K+, and other cations in the brine for water partitioning due to its higher charge density, resulting in selective uptake into the organic-rich phase.

[0031] In some embodiments, at 106, at least a portion of the organic-rich phase is separated from the multi-phase mixture at the first temperature to form a separated portion. In some embodiments, substantially all of the organic-rich phase is separated 106 as the separated portion. At TL, this separated portion includes a concentration of water extracted from the aqueous phase, as well as a concentration of Li+. In some embodiments, at least a portion of the aqueous phase can be collected as well to form a raffinate portion, which includes a concentration of cations that were not partitioned into the organic-rich phase.

[0032] In some embodiments, at 108, the separated portion is heated to a second temperature (TH). In some embodiments, TH is above about 60°C. In some embodiments, TH is between about 60°C and about 80°C. In some embodiments, TH is about 60°C, 65°C, 70°C, 75°C, or 80°C. As temperature increases, the solvent is switched to become more hydrophobic, thus decreasing solvent polarity and corresponding ability to solvate water and partitionedcations. This thermoresponsive decrease in hydrophilicity drives phase separation in the separated portion, forming a solvent product and an aqueous product. Also advantageously, Li+follows the product water as it demixes from the organic-rich phase and the solvent product, such that the product water has an elevated concentration of Li+relative to the solvent product and is enriched in lithium relative to the other alkali cations, achieving selective separation. In some embodiments, the separated portion is heated to an intermediate temperature prior to heating the separated portion to the second temperature at 108. In these embodiments, an intermediate product water can be recovered from the separated portion at the intermediate temperature. The remaining separated portion can then be further heated, e.g., to additional intermediate temperatures, the TH, etc., to recover additional product waters. In some embodiments, the intermediate temperature is between the first temperature and the second temperature. In some embodiments, the intermediate temperature is between about 20°C and about 55°C.

[0033] In some embodiments, at 110, at least a portion of the product water is recovered. In some embodiments, the product water has a concentration of Li+above about 5 g / L. In some embodiments, the product water has a concentration of Li+above about 10 g / L. In some embodiments, the product water has a concentration of Li+above about 15 g / L. In some embodiments, the product water has a concentration of Li+above about 20 g / L. In some embodiments, the product water has a concentration of Li+above about 25 g / L. In some embodiments, at 112, a lithium product is recovered from the product water by any suitable means.

[0034] Referring now to FIG. 2, some embodiments of the present disclosure are directed to a method 200 of treating brines. In some embodiments, at 202, a multi-phase mixture is prepared. As discussed above, in some embodiments, the multi-phase mixture includes one or more brines including a concentration of Li+. In some embodiments, the brines include a concentration of Li+and a concentration of non-Li+cations. In some embodiments, the brines include a concentration of Li+and a concentration of non-Li+alkali metal cations. In some embodiments, the brines include a concentration of Li+and a concentration of Na+, K+, or combinations thereof. In some embodiments, the brines include geothermal brines, oilfield brines, salt-lake brines, LiCl, NaCl, KC1, or combinations thereof. In some embodiments, the total cation concentration in one or more brines is above about 0.5, 1, 1.5, 2, 2.5, 3, etc. mol / L. In some embodiments, the total cation concentration in one or more brines is above about 3.5 mol / L, enabling recovery of product water from the brines with increased Li+concentration relative to the brines themselves, as will be discussed in greater detail below. In someembodiments, the [Li+] / [M+] in the one or more brines is below about 100: 1. In some embodiments, the [Li+] / [M+] in the one or more brines is below about 10: 1. In some embodiments, the [Li+] / [M+] in the one or more brines is below about 1 : 1. In some embodiments, the [Li+] / [M+] in the one or more brines is below about 1 : 10. In some embodiments, the [Li+] / [M+] in the one or more brines is below about 1 : 100. In some embodiments, the [Li+] / [M+] in the one or more brines is about 1 : 1000.

[0035] In some embodiments, multi-phase mixture includes one or more switchable- hydrophilicity solvents. In some embodiments, the hydrophilicity of the solvents is thermoresponsive. In some embodiments, the solvent is basic. In some embodiments, the solvent includes one or more hydrophilic moieties in a mainly hydrophobic structure. In some embodiments, the solvent is an amine solvent, e.g., a primary, secondary, or tertiary amine solvent. In some embodiments, the solvent includes diisopropylamine (DIP A), N,N- dimethylcyclohexylamine (DMCHA), dipropylamine (DPA), N-ethylcyclohexylamine (ECHA), triethylamine (TEA), tert-octylamine (TOA), diethylamine, ethylpropylamine, N,N- di ethylmethylamine, methylbutylamine, 1- methylbutylamine, 1 -ethylpropylamine, diallylamine, cyclohexylamine, N-ethylmethylallylamine, hexamethyleneimine, 1 -methylpiperidine, 2- m ethylpiperidine, 3 -methylpiperidine, 4-methylpiperidine, butyldimethylamine, tertbutyldimethylamine, ethylbutylamine, tert-butylethylamine, hexylamine, 2,6-dimethylpiperidine, 3,3-dimethylpiperidine, 3,5-dimethylpiperidine, N-methylcyclohexylamine, 2- methylcyclohexylamine, heptylamine, N-methyl-l,3-dimethylbutylamine; 1 -methylhexylamine, 1 -ethylpiperidine, 2-ethylpiperidine, dibutylamine, diisobutylamine, di-sec-butylamine, N,N- diisopropylethylamine, 1,5-dimethylhexylamine, 2-ethylhexylamine, octylamine, 1- propylpiperidine, triallylamine, N-isopropylcyclohexylamine, 3,3,5-trimethylcyclohexylamine, 1 -methyloctylamine, tripropylamine, tert-butylcyclohexylamine, di ethylcyclohexylamine, decylamine, dimethyloctylamine, dipentyl amine, dibutylethylenediamine, N,N,N',N'- tetramethyl-l,6-hexanediamine, 1 -methyldecylamine, dihexylamine, dodecylamine, tributylamine, triisobutylamine, C4H11N, C5H13N, CeHnN, CeHoN, CeHisN, C7H15N, C7H17N, C7H19N, QH17N, C8HI9N, C8H2IN, C9H15N, C9H19N, C9H21N, C10H21N, C10H23N, C10H24N2, C11H25N, C11H26N2, C12H27N, or combinations thereof.

[0036] In some embodiments, the multi-phase mixture includes one or more anionic components. In some embodiments, the anionic components includes T, Br , or combinations thereof. In some embodiments, the anionic components include Nal, NaBr, or combinations thereof. In some embodiments, the concentration of the anionic components in the multi-phase mixture is less than the concentration of Li+.

[0037] In some embodiments, at 204, the multi-phase mixture is equilibrated at a first temperature, e.g., TL identified above. As also discussed above, in some embodiments, the multi-phase mixture includes an organic-rich phase and an aqueous phase. In some embodiments, TL is below about 40°C. In some embodiments, TL is between about 5°C and about 40°C. In some embodiments, TL is about 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, or 40°C. In some embodiments, at temperature TL, at least some of the water in the aqueous phase, i.e., from the brines, partitions into the organic-rich phase. In some embodiments, Li+is preferentially extracted into the organic-rich phase with the water.

[0038] Still referring to FIG. 2, in some embodiments, at 206, at least a portion of the organic-rich phase is separated from the multi-phase mixture at the first temperature as a separated portion. In some embodiments, at least a portion of the aqueous phase can be collected as well to form a raffinate portion, which includes a concentration of cations that were not partitioned into the organic-rich phase. In some embodiments, the raffinate portion can be recycled for treatment with additional switchable-hydrophilicity solvents, e.g., at preparation 202. In some embodiments, at 208, the separated portion is then heated to a second temperature, e.g., TH identified above. As also discussed above, in some embodiments, TH is above about 60°C. In some embodiments, TH is between about 60°C and about 80°C. In some embodiments, TH is about 60°C, 65°C, 70°C, 75°C, or 80°C. In some embodiments, TH is about 80°C. As temperature increases, the solvent is switched to become more hydrophobic, thus decreasing solvent polarity and corresponding ability to solvate water and partitioned cations. Li+follows the product water as it demixes from the organic-rich phase, such that the product water has an elevated concentration of Li+relative to the solvent product.

[0039] In some embodiments, at 208, at least a portion of the product water recovered. In some embodiments, at 210, at least a portion of the solvent product is recycled to the multiphase mixture. In some embodiments, at 212, at least a portion of the solvent product is recycled to contact the raffinate portion to form an additional multi-phase mixture and enable further extraction of Li+from the raffinate portion.

[0040] Referring now to FIGs. 3 A-3B, embodiments of the present disclosure demonstrate the selective recovery of lithium over sodium from high-salinity brines, e.g., using full cycles for triethylamine (TEA), tert-octylamine (TOA), diisopropylamine (DIP A), N,N- dimethylcyclohexylamine (DMCHA), A-ethylcyclohexylamine (ECHA), and dipropylamine (DPA). The six solvents were equilibrated with 3.0 mol / L feed brines of equimolar LiCl and NaCl, i.e., 1.5 mol / L each. FIG. 3 A presents Li+and Na+(filled and emptycolumns, respectively) in the feed, raffinate, extract, product, and regenerated solvent using TO A as the solvent to illustrate the transport of the cations in embodiments of the present disclosure. The preferential extraction of lithium by the solvent upon contact with the brine is reflected in the elevated levels of Li+compared to Na+in the organic extract, as well as the greater depletion of Li+in the aqueous raffinate. Following phase disengagement of the separated portion, the ions in the organic phase are recovered in the aqueous product stream, i.e., product water, (corresponding columns of the extract and product are at the same heights, with a negligible amount of cations remaining in the regenerated solvent), thus enriching lithium relative to sodium. Moles of Li+and Na+in the exiting streams (raffinate, product, and regenerated solvent) are 92.3% and 93.0% of the entering feed brine, i.e., mole balance is substantially attained.

[0041] Selectivity for cation Mi over competing cation M2, ^+ / M+’ defined in Equation 1 below as the ratio of moles (n) of Mi to M2 in the product stream relative to the feed (denoted by superscripts p and f, respectively). (Equation 1)Therefore, the preferential extraction of Mi is signified by > 1, i.e., Mi is enrichedover M2. All of the investigated solvents were selective for Li+over Na+by at least 2.8* (TEA) and up to 9.9* (DPA) (columns in FIG. 3B, left vertical axis). All six solvents exhibited enrichment of lithium over sodium in the product water, indicating that the lithium selectivity is robust across different solvent chemical structures (branched / linear, cyclic / acyclic, and primary / secondary / tertiary amines). This preference for Li+persisted when the solvents were challenged with other alkali metal cations. Despite the similar characteristics of Li+, Na+, and K+, embodiments of the present disclosure enrich lithium over these competing monovalent cations from brine mixtures.

[0042] Extraction capacity, E, in Equation 2 below, is the moles of Li+recovered in the product water normalized by the moles of solvent (n is moles and subscript solv denotes solvent) and is presented in FIG. 3B (symbols, right vertical axis) for the six investigated solvents.£ = / 7LI+ foiv (Equation 2)The extraction capacities are expressed as mass of LiCl per unit mass of solvent. Extraction capacities of the investigated solvents range from 1 .83 / I 05to 3.77 / 102mol / mol, with TEAand TOA having the lowest and highest E, respectively (7.69 / 103and 12.4 g / kg). There is a weak correlation between S and E, signifying that the embodiments of the present disclosure are not strictly bound by a tradeoff between selectivity and extraction capacity that is commonly observed in other separation methods.

[0043] Referring now to FIG. 4, lithium concentrations in the product water of embodiments of the present disclosure are shown. TOA notably shows higher Li+concentrations in the product stream than in the feed (1.87 and 1.50 mol / L, respectively), i.e., the product stream is enriched in lithium relative to both sodium and water. High product stream Li+concentrations are favorable for the subsequent precipitation of lithium hydroxide or lithium carbonate, e.g., concentrations above about 5 g / L or, in some embodiments, above about 25 g / L. Note that effectively all Li+and Na+extracted into the organic phase is released into the aqueous phase, i.e., cation concentrations are practically identical in the extract and product water.

[0044] Referring now to FIG. 5A-5B, besides continental lithium brines, geothermal and oilfield brines hold promise as alternative lithium resources. In particular, in the U.S., the brine byproduct of geothermal electricity generation in the Salton Sea (Imperial Valley, CA) stands out for its considerable recovery potential, estimated to be over 3.4x 109kg of lithium (enough for >375 million electric vehicle batteries). However, in addition to the obstacle of low lithium concentrations (typically below 200 ppm) amidst a background of dramatically higher alkali metal cation concentrations ([Na+] and [K+] are about 10-1,000 times higher than [Li+]), recovering lithium from these unconventional brine sources can potentially be complicated by the presence of other multivalent cations in the water chemistry, such as calcium and magnesium. The embodiments of the present disclosure were evaluated in a more realistic brine matrix simulating the main ions of post-flash geothermal brines from the Salton Sea as shown in Table 1 below. The ionic strength of the simulated brine was adjusted to 3.0 mol / L (while maintaining the cation ratios), although the ionic strength of Salton Sea geothermal brines is about 4.8 mol / L, to enable comparison with the results of the binary mixtures in FIG. 5A. As such, the Li+content of the simulated feed was 2. I >102mol / L (147.9 ppm), lower than the actual concentration of about 3.0 / 102mol / L (about 206.5 ppm).Ion Concentration Molar Ratio of Ion to Li+[mol / L] [mol / mol]Li+2.1 / 1021.0Na+1.6 74K+0.25 12Mg2+4.6 / IO30.22Ca2+0.42 20CF 2.7 127SO426.2 / 1040.029Table 1. Composition of the simulated Salton Sea brine feed adjusted to 3.0 mol / L ionic strength.

[0045] Referring specifically to FIG. 5B, lithium selectivities with the simulated Salton Sea brine using embodiments of the present disclosure are in the same range as the equimolar and lithium-dilute binary systems. With a Li:Na molar ratio of 1 :74 in the simulated brine, 5O / +was 7.76 and 3.50 for DPA and TOA, respectively. In the simulated brine, Li+:K+=1 : 12, and S°'+= 4.62 for TOA, a decline from 6.45 in the feed with Li+:Na+= 1 : 1,000. In contrast, = 12.2 for DPA, comparable to the selectivity of 10.5 in the lithium-dilute binary systems. The preferential extraction of Li+over Na+and K+by embodiments of the present disclosure is upheld even with the complexity of the simulated geothermal brine.

[0046] For a demonstration of practical applications, the embodiments of the present disclosure were selective against magnesium present in the simulated brine, and magnesium did not impact lithium recovery. The similar physicochemical properties of Li+and Mg2+can pose limitations on selectivity, e.g., atomic size, electronegativity, and charge-to-size ratio can frustrate effective separation for several DLE technologies. Further, for the conventional lithium production method of brine extraction, i.e., evaporation followed by precipitation, magnesium can contaminate the Li2CO3(s) product because of the similar carbonate precipitation chemistry. However, no Mg2+was detected in either the organic separation portion or the aqueous raffinate portion, i.e., During extraction, some switchable solvent partitions into thelithium brine. Due to the basicity of TOA and DPA (p b = 3.35 and 2.63, respectively), the aqueous phase pH increased, e.g., to 12.0 and 11.9, respectively, driving Mg2+present in the feed brine to precipitate out as Mg(OH)2(s). However, S^+ / c^ s are 1.23 and 1.62 for TOA and DPA, respectively. Further, as the aqueous phase pH and Ca2+concentrations are not high enoughfor Ca(0H)2(s) precipitation, no calcium was removed from the liquid phases. The magnesium concentration in the synthetic brine used in these exemplary embodiments was low relative to the lithium concentration, and the precipitation of magnesium hydroxides will be amplified at higher magnesium concentrations. The robust selectivity in complex brines, coupled with tolerance for Mg2+, point to the broad applicability of the embodiments of the present disclosure as a direct lithium extraction technology.

[0047] Referring now to FIGs. 6A-6B, consecutive semi-batch extraction cycles can increase lithium recovery while maintaining lithium selectivity. Semi-batch embodiments of the present disclosure using regenerated solvent were demonstrated over four consecutive extraction cycles. 3.0 mol / L feed brines with an initial Li+:Na+ratio of 1 : 100 were equilibrated with an equal mass of TOA (FIG. 6A) or DPA (FIG. 6B). After each extraction cycle, the raffinate portion and solvent product were recombined for additional extraction. Cation yield, F^+ , can be defined in Equation 3 below as the percentage of initial feed M+recovered in the product stream. p+IPpYp+= — - x 100% (Equation 3)Myf+IPfIn Equation 3, JM+is the mass fraction of M+in the product or feed phase of weight W. Li+and Na+yields over the four cycles with TOA (FIG. 6A) or DPA (FIG. 6B) are visualized as stacked columns, with the summedrepresenting cumulative yield after sequential extractions.

[0048] At the end of four cycles, 39.3% of Li+from the initial feed was recovered using TOA, demonstrating that the embodiments of the present disclosure can achieve practical recovery yields from lithium brines. Compared to Li+, the proportions of Na+from the initial feed ending up in the product streams are substantially lower, with 9.2% and 0.52% aggregated over the multiple cycles for TOA and DPA, respectively.

[0049] The selectivity for lithium over sodium for each cycle is presented as well, along with the cumulative selectivity across all four extraction cycles, i.e., relative to the initial feed brine composition and equivalent to ^^IPi+ / ^^'a+• With TOA as the switchable solvent, holds approximately constant across the repeated cycles. The cumulative lithium selectivity is 4.3, lower than *S^ / N+ of 4.9 in the first cycle. Selectivity slightly declinesfor the third and fourth extractions because Li+concentration in the raffinate portion, which becomes the feed for the subsequent cycle, is progressively decreasing as Li+is preferentially recovered in the product water. On the other hand, the change in raffinate Li+:Na+ratio for DPA over consecutive extraction cycles is negligible due to the relatively lower Fp.Concurrently, Li+raffinate concentration increases due to water extraction. Hence,for DPA rises with each subsequent cycle (from 9.2 to 10.2 between the first and fourth extractions), with the cumulative lithium selectivity being 9.6. Overall, repeated cycles can progressively extract more Li+from lithium brines while largely maintaining selectivity.

[0050] Referring now to FIGs. 7A-7C, embodiments of the present disclosure can handle a wide range of brine salinities. Notably, lithium selectivity increases for more concentrated saline feeds showing that the embodiments of the present disclosure are suited for treating hypersaline brines. Many unconventional lithium resources, such as oilfield and geothermal brines, fall into this category. Further, some embodiments of the present disclosure achieve both higher yield and higher selectivity as feed salinity increases, e.g., see FIG. 7C for TOA. In some embodiments, the systems and methods of the present disclosure are selective for lithium over competing cations and non-dilutive, i.e., the product water has a higher Li+concentration than the feed brine, facilitating the subsequent precipitation of lithium salts, e.g., without additional dewatering. With sufficiently concentrated feed brines, the lithium-enriched product water has higher lithium concentrations than the brine feeds themselves, as demonstrated in FIG. 7C using brines with feed concentrations above about 3.5 mol / L.

[0051] Referring now to FIGs. 8A-8C, as discussed above, in some embodiments of the present disclosure, feed brines can be doped with one or more anionic components to increase both lithium recovery and selectivity. Referring specifically to FIGs. 8A-8B, in some embodiments, sodium bromide (NaBr) was doped into the feed brine that contained sufficient LiCl, NaCl, and KC1 such that the cation proportions were the same as in the Salton Sea geothermal resource. For the same total feed concentration, both Li+ / Na+and Li+ / K+were higher when NaBr is used to increase the feed concentration. Further, extraction capacity trended proportionally to lithium recovery yield. Referring specifically to FIG. 8C, sodium iodide was progressively doped into 3 M, 1 : 100 lithium: sodium brines, which were then equilibrated with DIPA. Low concentrations of Nal, i.e., when [I ] < [Li+], demonstrated increased lithium yield and selectivity. Once [I ] > [Li+], lithium yield increased at the expense of lithium selectivity.

[0052] Referring now to FIG. 9, some embodiments of the present disclosure are directed to a system 900 of recovering a lithium product from a feedstream. In some embodiments, system 900 includes a feedstream 902 in fluid communication with a fluid source 904. In some embodiments, fluid source 904 is from any suitable source, e.g., existing in the natural environment, effluent from industrial processes, etc. In some embodiments, fluid source 904, and thus feedstream 902, includes brines, produced waters, or combinations thereof. In some embodiments, as discussed above, the brines include a concentration of Li+. In some embodiments, the brines include a concentration of Li+and a concentration of non-Li+cations. In some embodiments, the brines include a concentration of Li+ and a concentration of non-Li+alkali metal cations. In some embodiments, the brines include a concentration of Li+and a concentration of Na+, K+, or combinations thereof. In some embodiments, the brines include geothermal brines, oilfield brines, salt-lake brines, LiCl, NaCl, KC1, or combinations thereof.

[0053] In some embodiments, system 900 includes a solvent source 906. In some embodiments, as discussed above, solvent source 906 includes one or more switchable- hydrophilicity solvents. In some embodiments, the hydrophilicity of the solvents is thermoresponsive. In some embodiments, the solvent is basic. In some embodiments, the solvent includes one or more hydrophilic moieties in a mainly hydrophobic structure. In some embodiments, the solvent is an amine solvent, e.g., a primary, secondary, or tertiary amine solvent. In some embodiments, the solvent includes diisopropylamine (DIP A), N,N- dimethylcyclohexylamine (DMCHA), dipropylamine (DPA), N-ethylcyclohexylamine (ECHA), triethylamine (TEA), tert-octylamine (TOA), diethylamine, ethylpropylamine, N,N- di ethylmethylamine, methylbutylamine, 1- methylbutylamine, 1 -ethylpropylamine, diallylamine, cyclohexylamine, N-ethylmethylallylamine, hexamethyleneimine, 1 -methylpiperidine, 2- m ethylpiperidine, 3 -methylpiperidine, 4-methylpiperidine, butyldimethylamine, tertbutyldimethylamine, ethylbutylamine, tert-butylethylamine, hexylamine, 2,6-dimethylpiperidine, 3,3-dimethylpiperidine, 3,5-dimethylpiperidine, N-methylcyclohexylamine, 2- methylcyclohexylamine, heptylamine, N-methyl-l,3-dimethylbutylamine; 1 -methylhexylamine, 1 -ethylpiperidine, 2-ethylpiperidine, dibutylamine, diisobutylamine, di-sec-butylamine, N,N- diisopropylethylamine, 1,5-dimethylhexylamine, 2-ethylhexylamine, octylamine, 1- propylpiperidine, triallylamine, N-isopropylcyclohexylamine, 3,3,5-trimethylcyclohexylamine, 1 -methyloctylamine, tripropylamine, tert-butylcyclohexylamine, di ethylcyclohexylamine, decylamine, dimethyloctylamine, dipentyl amine, dibutylethylenediamine, N,N,N',N'- tetramethyl-l,6-hexanediamine, 1 -methyldecylamine, dihexylamine, dodecylamine, tributylamine, triisobutylamine, C4H11N, C5H13N, CeHnN, CeHoN, CeHisN, C7H15N, C7H17N,C7H19N, C8HI7N, C8HI9N, C8H2IN, C9H15N, C9H19N, C9H21N, C10H21N, C10H23N, C10H24N2, C11H25N, C11H26N2, C12H27N, or combinations thereof.

[0054] In some embodiments, system 900 includes an extractor 908 in fluid communication with feedstream 902 and solvent source 906. In some embodiments, system 900 includes a plurality of extractors 908, e.g., arranged in parallel, arranged in series, or combinations thereof. In some embodiments, extractor 908 is in fluid communication with an anion source 910. In some embodiments, anion source 910 includes one or more anionic components. In some embodiments, as discussed above, the anionic components include I’, Br , or combinations thereof. In some embodiments, brines from feedstream 902 and solvent from solvent source 906 are combined in extractor 908. In some embodiments, brines from feedstream 902, solvent from solvent source 906, and anions from anion source 910 are combined in extractor 908. The mixing of these various sources in extractor 908 yields a multiphase mixture.

[0055] As discussed above, in some embodiments, the multi-phase mixture is formed in extractor 908 at a temperature TL. In some embodiments, the multi-phase mixture is formed at different temperatures and brought to a first temperature TL. In some embodiments, the multiphase mixture is mixed and equilibrated in extractor 908. In some embodiments, the multi-phase mixture is mixed in extractor 908 then subsequently removed for equilibration in a second reactor 908', e.g., for subsequent equilibration.

[0056] In some embodiments, TL is below about 40°C. In some embodiments, TL is between about 5°C and about 40°C. In some embodiments, TL is about 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, or 40°C. At temperature TL, the multi-phase mixture equilibrates. In some embodiments, feedstream 902 is introduced at the top of extractor 908 and contacts solvent therein at a desired temperature, e.g., temperature TL. In some embodiments, extractor 908 includes at least a first outlet 908A to facilitate removal of one or more outlet streams.Extractors 908 can be of any suitable shape and volume to accommodate a desired volume of liquid, e.g., feedstream 902. In one exemplary embodiment, extractor 908 has a generally cylindrical shape, e.g., a liquid-liquid extraction column. The solvent progressively extracts water and cations from the denser aqueous phase as it sinks toward the bottom of extractor 908, forming an organic-rich light phase on top and a denser aqueous phase below. Additionally, as discussed above, as water from the brines partitions into the solvent phase, it preferentially brings with it a portion of the Li+from the brines as well.

[0057] In some embodiments, at least one of the organic-rich phase and the aqueous phase is removed via first outlet 908A. In some embodiments, at least a portion of the organic- rich phase is removed from extractor 908, e.g., as separated portion. In some embodiments, at least a portion of the aqueous phase is removed from extractor 908, e.g., as the raffinate portion. In some embodiments, the separated portion is removed as separated portion stream 912 and fed to another extractor 908". In some embodiments, the raffinate portion is recycled, e.g., as raffinate portion stream 914 for further contact with switchable-hydrophilicity solvents from solvent source 906 in extractor 908.

[0058] In some embodiments, the temperature of the organic-rich phase, e.g., the separated portion, is raised to reduce the hydrophilicity of the solvent to demix a solvent product and a product water including a concentration of Li+from feedstream 902. In some embodiments, as discussed above, the organic-rich portion is raised to a temperature TH. In some embodiments, TH is above about 60°C. In some embodiments, TH is between about 60°C and about 80°C. In some embodiments, TH is about 60°C, 65°C, 70°C, 75°C, or 80°C. In some embodiments, the product water can then be recovered, e.g., as product water stream 916. In some embodiments, the solvent product can be recycled, e.g., via solvent product stream 918 for contacting with additional brines from feedstream 902 in extractor 908.

[0059] In some embodiments, system 900 includes a temperature controller 920. In some embodiments, temperature controller 920 is in thermal communication with extractors 908 and / or separated portion stream 912, e.g., via a heat source, cooling system, etc. In some embodiments, temperature controller 920 is in thermal communication with feedstream 902, raffinate portion stream 914, product water stream 916, solvent product stream 918, or combinations thereof. Temperature controller 920 is configured to maintain a predetermined temperature in a first location in system 900, e.g., temperature TL in extractor 908', and another predetermined temperature in at least a second location in system 900, e.g., temperature TH in extractor 908". The heat input to system 900 can be supplied from low-grade thermal sources. In some embodiments, the heat is supplied from renewable energy sources, e.g., wind, solar, hydrothermal, etc., or combinations thereof.

[0060] Systems and methods of the present disclosure advantageously use thermoresponsive, switchable-hydrophilicity amine solvents for lithium extraction. The separation of lithium from potassium and sodium is a beneficial step in the production of lithium from brines. Two distinct liquid layers (extract and raffinate) form following mixture of a solvent with a thermoresponsive affinity for salt and water with a hypersaline brines containinglithium and other alkali metal cations at an extraction temperature, ions along with water can partition into the switchable solvent. Lithium is preferentially extracted over other alkali metal cations. The extract can then be warmed to a disengagement temperature, where the previously extracted ions and water demix from the organic phase, yielding product water stream enriched in lithium utilizing only mild temperature swings and an amount of thermoresponsive solvent, which can be recycled for use in treatment of and lithium extraction from additional hypersaline feed brines.

[0061] A range of switchable solvents, extraction temperatures, and feed lithium / sodium ratios were identified. The embodiments of the present disclosure maintain selectivity for lithium in complex brine feeds, reflective of real geothermal / oilfield brine sources of lithium.Further, a fundamental understanding of the thermodynamics of salt and water partitioning has been demonstrated, enabling efficacious operational configurations to increase lithium selectivity and / or yield. Lithium extraction is highly beneficial for energy security.

[0062] Although the invention has been described and illustrated with respect to exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without parting from the spirit and scope of the present invention.

Claims

CLAIMSWhat is claimed is:

1. A method of recovering a lithium product from brines, comprising: mixing one or more brines with one or more switchable-hydrophilicity solvents to form a multi-phase mixture, the brines including a concentration of lithium cations (Li+) and a concentration of non-Li cations; equilibrating the multi-phase mixture at a first temperature including an organic- rich phase and an aqueous phase; separating at least a portion of the organic-rich phase from the multi-phase mixture at the first temperature to form a separated portion; heating the separated portion to a second temperature to form a solvent product and a product water, wherein the product water has an elevated concentration of Li+relative to the solvent product, and recovering at least a portion of the product water.

2. The method according to claim 1, further comprising: collecting at least a portion of the aqueous phase to form a raffinate portion, and contacting the raffinate portion with at least a portion of the solvent product to form an additional multi-phase mixture.

3. The method according to claim 1, wherein the total cation concentration in the one or more brines is above about 3.5 mol / L.

4. The method according to claim 1, wherein the ratio of concentration of Li+to the concentration of non-Li cations ([Li+] / [M+]) in the one or more brines is below about 1 : 1.

5. The method according to claim 4, wherein the [Li+] / [M+] in the one or more brines is below about 1 : 100.

6. The method according to claim 1, wherein the first temperature is below about 40°C.

7. The method according to claim 1, wherein the second temperature is above about 60°C.

8. The method according to claim 1, wherein the brine includes geothermal brines, oilfield brines, salt-lake brines, LiCl, NaCl, KC1, or combinations thereof.

9. The method according to claim 1, wherein the switchable-hydrophilicity solvent includes diisopropylamine (DIP A), N,N-dimethylcyclohexylamine (DMCHA), dipropylamine (DPA), N-ethylcyclohexylamine (ECHA), triethylamine (TEA), tert-octylamine (TOA), di ethylamine, ethylpropylamine, N,N-di ethylmethylamine, methylbutylamine, 1- methylbutylamine, 1 -ethylpropylamine, diallylamine, cyclohexylamine, N- ethylmethylallylamine, hexamethyleneimine, 1 -methylpiperidine, 2-m ethylpiperidine, 3- methylpiperidine, 4-methylpiperidine, butyldimethylamine, tert-butyldimethylamine, ethylbutylamine, tert-butylethylamine, hexylamine, 2,6-dimethylpiperidine, 3,3- dimethylpiperidine, 3,5-dimethylpiperidine, N-methylcyclohexylamine, 2- methylcyclohexylamine, heptylamine, N-methyl-l,3-dimethylbutylamine; 1- methylhexylamine, 1 -ethylpiperidine, 2-ethylpiperidine, dibutylamine, diisobutylamine, di-sec-butylamine, N,N-diisopropylethylamine, 1,5-dimethylhexylamine, 2- ethylhexylamine, octylamine, 1 -propylpiperidine, triallylamine, N- isopropylcyclohexylamine, 3,3,5-trimethylcyclohexylamine, 1 -methyloctylamine, tripropylamine, tert-butylcyclohexylamine, diethylcyclohexylamine, decylamine, dimethyloctylamine, dipentylamine, dibutylethylenediamine, N, N,N',N' -tetramethyl- 1,6- hexanediamine, 1 -methyldecylamine, dihexylamine, dodecylamine, tributylamine, triisobutylamine, C4HnN, C5H13N, CeHnN, C6HI3N, CeHisN, C7H15N, C7H17N, C7H19N, QH17N, C8HI9N, C8H2IN, C9H15N, C9H19N, C9H21N, C10H21N, C10H23N, C10H24N2, C11H25N, C11H26N2, C12H27N, or combinations thereof.

10. The method according to claim 1, wherein the multi-phase mixture further comprises one or more anionic components, wherein the anionic components include iodine anions (T), bromine anions (Br ), or combinations thereof.

11. The method according to claim 10, wherein the concentration of the anionic components is less than the concentration of Li+.

12. The method according to claim 10, wherein the ratio of the anionic components to chloride is varied between pure chloride, [X'] / [C1‘] = about 1 :3, [X'] / [C1‘] = about 1 : 1, [X' ] / [CT] = about 3: 1, and pure anionic component.

13. The method according to claim 1, wherein heating the separated portion to a second temperature to form a solvent product and a product water further comprises:heating the separated portion to an intermediate temperature prior to heating the separated portion to the second temperature, and recovering an intermediate product water from the separated portion at the intermediate temperature, wherein the intermediate temperature is between the first temperature and the second temperature.

14. The method according to claim 13, wherein the intermediate temperature is between about 20°C and about 55°C.

15. The method according to claim 1, wherein the product water has a concentration of Li+above about 25 g / L.

16. A method of recovering a lithium product from brines, comprising: preparing a multi-phase mixture, the multi-phase mixture including: one or more brines including a concentration of lithium cations (Li+) and a concentration of non-Li cations; and one or more switchable-hydrophilicity solvents, equilibrating the multi-phase mixture at a first temperature including an organic- rich phase and an aqueous phase; separating at least a portion of the organic-rich phase from the multi-phase mixture at the first temperature to form a separated portion; heating the separated portion to an intermediate temperature, recovering an intermediate product water from the separated portion at the intermediate temperature, heating the separated portion to a second temperature to form a solvent product and a product water, wherein the product water has an elevated concentration of Li+relative to the solvent product and the intermediate temperature is between the first temperature and the second temperature; and recovering at least a portion of the product water,wherein the switchable-hydrophilicity solvent includes diisopropylamine (DIP A), N,N-dimethylcyclohexylamine (DMCHA), dipropylamine (DPA), N- ethylcyclohexylamine (ECHA), triethylamine (TEA), tert-octylamine (TOA), di ethylamine, ethylpropylamine, N,N-di ethylmethylamine, methylbutylamine, 1- methylbutylamine, 1 -ethylpropylamine, diallylamine, cyclohexylamine, N- ethylmethylallylamine, hexamethyleneimine, 1 -methylpiperidine, 2- methylpiperidine, 3 -methylpiperidine, 4-methylpiperidine, butyldimethylamine, tert-butyldimethylamine, ethylbutylamine, tert-butylethylamine, hexylamine, 2,6- dimethylpiperidine, 3, 3 -dimethylpiperidine, 3,5-dimethylpiperidine, N- methylcyclohexylamine, 2-methylcyclohexylamine, heptylamine, N-methyl-1,3- dimethylbutylamine; 1 -methylhexylamine, 1 -ethylpiperidine, 2-ethylpiperidine, dibutylamine, diisobutylamine, di-sec-butylamine, N,N-diisopropylethylamine, 1,5-dimethylhexylamine, 2-ethylhexylamine, octylamine, 1 -propylpiperidine, triallylamine, N-isopropylcyclohexylamine, 3,3,5-trimethylcyclohexylamine, 1- methyloctylamine, tripropylamine, tert-butylcyclohexylamine, diethylcyclohexylamine, decylamine, dimethyloctylamine, dipentylamine, dibutyl ethyl enedi amine, N,N,N' ,N' -tetramethyl - 1 , 6-hexanedi amine, 1 - methyldecylamine, dihexylamine, dodecylamine, tributylamine, triisobutylamine, C4H11N, C5H13N, CeHnN, C6H13N, C6HI5N, C7H15N, C7H17N, C7H19N, CsHnN, C8HI9N, C8H21N, C9H15N, C9H19N, C9H21N, C10H21N, C10H23N, C10H24N2, C11H25N, C11H26N2, C12H27N, or combinations thereof, and wherein the brine includes geothermal brines, oilfield brines, salt-lake brines, LiCl, NaCl, KC1, or combinations thereof.

17. The method according to claim 16, wherein: the ratio of concentration of Li+to the concentration of non-Li cations ([Li+] / [M+]) in the one or more brines is below about 1:1, and the total cation concentration in the one or more brines is above about 3.5 mol / L.

18. The method according to claim 16, further comprising: collecting at least a portion of the aqueous phase to form a raffinate portion, and contacting the raffinate portion with at least a portion of the solvent product to form an additional multi-phase mixture.

19. The method according to claim 16, wherein the [Li+] / [M+] in the one or more brines is below about 1 : 100.

20. The method according to claim 16, wherein the multi-phase mixture includes one or more anionic components, the anionic component including iodine anions (T), bromine anions (Br ), or combinations thereof, wherein: the concentration of the anionic components is less than the concentration of Li+, or the ratio of the anionic components to chloride is varied between pure chloride, [X'] / [CT] = about 1 :3, [X'] / [C1‘] = about 1 : 1, [X'] / [C1‘] = about 3: 1, and pure anionic component.

21. A method of treating brines, comprising: preparing a multi-phase mixture, the multi-phase mixture including: one or more brines including a concentration of lithium cations (Li+) and a concentration of non-Li cations; one or more switchable-hydrophilicity solvents, and one or more anionic components including iodine anions (T), bromine anions (Br ), or combinations thereof; equilibrating the multi-phase mixture at a first temperature including an organic- rich phase and an aqueous phase; separating at least a portion of the organic-rich phase from the multi-phase mixture at the first temperature to form a separated portion; heating the separated portion to a second temperature to form a solvent product and a product water, wherein the product water has an elevated concentration of Li+relative to the solvent product; recovering at least a portion of the product water, and recycling at least a portion of the solvent product to the multi-phase mixture, wherein the ratio of concentration of Li+to the concentration of non-Li cations ([Li+] / [M+]) in the one or more brines is below about 1 : 100,wherein the total cation concentration in the one or more brines is above about 3.5 mol / L, and wherein the concentration of the anionic components is less than the concentration of Li+, or the ratio of the anionic components to chloride is varied between pure chloride,[X'] / [C1‘] = about 1 :3, [X'] / [C1‘] = about 1 : 1, [X'] / [C1‘] = about 3: 1, and pure anionic component.

Images