Thin film composite cation exchange membranes and methods and systems thereof

Abstract

Thin film composite cation exchange membranes and systems and methods thereof, and, more particularly, thin film composite cation exchange membranes for monovalent / divalent ion separation in electrodialysis and thin film composite cation exchange membranes for achieving Li separation.

Description

Attorney Docket No.: 072174-05101 THIN FILM COMPOSITE CATION EXCHANGE MEMBRANES AND METHODS AND SYSTEMS THEREOF CROSS-REFERENCED TO RELATED PATENT APPLICATIONS

[0001] The application claims priority to U.S. Patent Appl. Serial No.63 / 511,464, to Qilin Li, et al., entitled “Methods Of Concentration Countered Electrodialysis For Lithium Extraction,” filed June 30, 2023, which patent application is commonly owned by the owner of the present invention and is incorporated herein in its entirety. TECHNICAL FIELD

[0002] The present invention relates thin film composite cation exchange membranes and systems and methods thereof, and, more particularly, thin film composite cation exchange membranes for monovalent / divalent ion separation in electrodialysis and thin film composite cation exchange membranes for achieving Li separation. STATEMENT REGARDING FEDERALLY FUNDED RESEARCH

[0003] This invention was made with government support under Grant No. EEC-1449500, awarded by the National Science Foundation. The government has certain rights in the invention. BACKGROUND

[0004] Desalination of alternative water sources including seawater, brackish water, and wastewater is an increasingly important way to supplement conventional fresh water sources to alleviate water stress related conflicts. Membrane desalination processes, such as pressure-driven reverse osmosis (RO) and nanofiltration (NF), and electro-driven electrodialysis (ED), have become the leading technologies in the desalination market, due to their higher energy efficiency compared to conventional thermal desalination processes. To date, NF and RO are the most prevalent desalination technologies due to their efficient removal of a broad spectrum of solutes at a relatively low cost. However, water recovery in NF and RO processes is limited by the very highAttorney Docket No.: 072174-05101 pressure needed to overcome the osmotic pressure of the concentrated brine as well as fouling and scaling of the membrane.

[0005] ED uses an electrical field to separately remove positively and negatively charged species through ion exchange membranes (IEMs), which selectively transport the counter-ions (e.g., cations as to cation exchange membranes) and reject the co-ions via Coulomb force. It operates at ambient temperature and pressure, and has been shown to be more energy efficient than other desalination methods when treating saline water with total dissolved solids (TDS) concentration up to 10,000 mg / L. Compared to RO, ED can achieve much higher water recovery, demand less chemical and energy consumption, have long membrane service life and is easy to operation. Over 85% of water recovery can be achieved by ED without extensive pretreatments, as it is more tolerant to silica, hardness, and organic matters, which normally lead to severe scaling and fouling issues in pressurized membrane processes.

[0006] However, current IEMs do not offer desired monovalent / divalent permselectivity. The higher divalent ion permselectivity of most IEMs may lead to product water being depleted with hardness and alkalinity, which is not suitable for human consumption or agriculture irrigation. Such product water is also unstable and corrosive, posing a risk to the distribution pipelines as well as water quality at the point of use. Post-treatment is usually necessary to condition the water, which increases energy and chemical consumption and hence the overall cost of desalination. In addition, higher divalent ion permselectivity also leads to high divalent ion concentrations in the concentrate stream, which could induce mineral scale formation and limit the water recovery of the ED process. Ion permselectivity of an IEM can play a crucial role in determining the resource recovery and product water quality of an ED system. The ability to tune the monovalent permselectivity over divalent ions of IEMs is therefore highly desirable for enhancing EDAttorney Docket No.: 072174-05101 performance in desalinating and extracting valuable ionic products from various saline source waters.

[0007] Several approaches have been explored to develop monovalent-selective IEMs, albeit with limited success. A positively charged coating can be applied to a cation exchange membrane (CEMs) by applying a cationic polymer (e.g., polyethyleneimine, polypyrrole, and polyaniline), a layer-by-layer (LBL) assembled polyelectrolyte multilayer with a net positive charge, or by introducing cationic functional groups on the CEM surface. Because divalent cations experience stronger repulsion from the positively-charged surface than monovalent cations, the permselectivity of monovalent over divalent cations has been shown to increase by several folds using this method. However, this strategy also increases the repulsion to monovalent cations, leading to reduced monovalent ion permeability and hence higher energy consumption and membrane use. Moreover, the selectivity decreases with increasing TDS as a result of charge screening and double layer compression.

[0008] Another approach uses selective adsorbents as additives in IEMs. Higher affinity of the selective adsorbent for the target ion is anticipated to increase its concentration in the membrane matrix, and therefore increase its permeability through the membrane. Nevertheless, the membrane permselectivity obtained was much lower than the selectivity of the adsorbent, which may be attributed to the defects formed at the adsorbent / membrane polymer interface, as well as the preferential transport of ions through the membrane polymer phase instead of the adsorbents. The size difference between divalent and monovalent ions has also been exploited to improve monovalent permselectivity. NF or NF-like membranes have been tested in ED systems and demonstrated a Na+ / Mg2+selectivity up to 7. However, these membranes are not ion conductive,Attorney Docket No.: 072174-05101 and have little to no selectivity between cations and anions. Therefore, they cannot be used as IEMs for ED.

[0009] Accordingly, there remains a great need for higher permeability, monovalent ion selective IEMs to improve performance of ED in desalination and brine concentration applications.

[0010] Furthermore, the urgent need to achieve net zero carbon emission requires accelerated transition from fossil fuel-based energy supply to renewable energy. This has drastically increased the demand for batteries needed for electric vehicles and energy storage facilities, and therefore the demand for lithium, the critical material used in batteries. Beyond its role in energy, lithium plays a vital role in medical research, nuclear fusion research, and lubricants. However, the lithium production rate, even with the expected expansion, is insufficient to meet the market demand, with the projected global deficit growing to more than 750,000 mt of LCE per year by 2030.

[0011] Currently, most Li resources are enriched either in hard rocks or brines like geothermal brine and salty lakes. Compared to hard rock mining, lithium extraction from lithium-containing geothermal brine (lithium > 15 million mt for US) and oil and gas produced water (> 0.75 million mt for US), is preferential due to larger global storage with less environmental impact. However, the conventional evaporation process is only economically viable for lithium brines with high lithium concentrations (~g / L). It is inefficient and expensive due to the very low Li recovery (<50%) and the slow process, and is also water intensive.

[0012] Therefore, advanced technologies have been developed to extract lithium directly from the brine, i.e., without evaporation, to achieve higher lithium recovery at a faster rate. These technologies are known as direct lithium extraction (DLE). Current DLE methods include adsorption, ion exchange, solvent extraction, and membrane processes, which have demonstrated largely improved lithium recovery of over 80%. However, these emerging DLE technologies faceAttorney Docket No.: 072174-05101 significant technical barriers and suffer from high operational cost. For example, adsorption based DLE technologies require the addition of soda ash and lime to adjust pH and precipitate out the divalent ions, leading to high chemical consumption and chemical sludge production. The costs of materials, chemicals, and utilities usually account for over 50% of the total operating cost.

[0013] A few ion sieves, e.g., lithium magnesium oxide (LMO) and lithium titanium oxide (LTO), have demonstrated exceptional lithium selectivity over other competing ions, but they have very slow adsorption and desorption kinetics. With existing ion sieve materials, high lithium selectivity can only be achieved under basic condition (pH>9). Moreover, large quantities of harsh chemicals (e.g., HCl, ammonia) and fresh water are required for lithium stripping and adsorbent regeneration. Similarly, solvent extraction, although showing Li selectivity, requires a large volume of organic solvents with high environmental risk and high costs. Existing membrane processes (e.g., NF, and ED) are limited by the lack of Li selectivity and require high energy consumption when dealing with high salinity brines due to the high osmotic pressure or reduced charge efficiency.

[0014] Ion exchange membranes (IEMs) are used in electrodialysis and membrane capacitive deionization processes to separate cations from anions. They are highly attractive for applications that require separation of ions from a complex brine. Despite the high separation efficiency between cations and anions, conventional IEMs are not discriminative among ions of the same charge. However, many applications require selective removal or recovery of certain target ions, including direct lithium extraction (DLE). Divalent cations in brine such as Ca2+and Mg2+must be thoroughly removed from the brine as they adversely impact the purity of the final Li2CO3or LiOH products. Also, monovalent cations like Na+and K+are present at much higher concentrations compared with Li+in most natural and waste brines. Their presence would drastically increase energy consumption for lithium extraction by an ED process without lithiumAttorney Docket No.: 072174-05101 selectivity. Some effort has been devoted to developing monovalent selective cation exchange membranes, but good selectivity between Li+and other monovalent ions has not been achieved.

[0015] Consequently, there are great needs for ion exchange membranes with tunable permselectivity among different ions for energy efficient desalination, and cation exchange membranes with high lithium selectivity over background ions, including calcium, magnesium, sodium and potassium, for fast and continuous lithium extraction from brine sources. SUMMARY OF THE INVENTION

[0016] The present invention relates thin film composite cation exchange membranes and systems and methods thereof, and, more particularly, thin film composite cation exchange membranes for monovalent / divalent ion separation in electrodialysis and thin film composite cation exchange membranes for achieving Li separation.

[0017] The present invention relates to an improved selective electrodialysis system and a method for using such system to extract lithium from geothermal brine, oil and gas field brine, wastewater and other aqueous solutions. The present invention relates to the field of selective electrodialysis for desalination of brine sources. In particular, the present invention relates to an improved selective electrodialysis system with tuned permselectivity and method for using such system to treat a brine source based on the brine source quality and the desired end use of the product water from such system.

[0018] The present invention is directed to systems and methods for energy efficient lithium extraction through the use of highly selective electrodialysis. The lithium selective electrodialysis system combines divalent ion rejection by selective membrane development and monovalent competing ion rejection by both selective membrane development and process optimization to improve lithium extraction in a manner that is energy efficient and cost-effective.Attorney Docket No.: 072174-05101

[0019] To address the need disclosed above, the electrodialysis system utilizes a service platform that communicatively couples the integrated monitoring stations using edge computing to allow for optimal data storage and transmission. Accordingly, in certain embodiments, the lithium selective electrodialysis system and corresponding method of use is capable of selectively extracting lithium with high purity, high recovery, high energy efficiency, low chemical and water consumption, and a relatively high speed using continuous operation.

[0020] In general, in one embodiment, the invention features a method for selectively recovering lithium from a brine source. The method includes introducing a brine source, wherein the brine source comprises lithium ions. The method also includes introducing the brine source to an electrodialysis cell, wherein the electrodialysis cell includes a cathode, an anode, a feed brine channel, an extractant channel, an anolyte channel, an anion-exchange membrane, and a selective cation exchange membrane having a thin film composite structure. The method also includes introducing a tailored aqueous extractant solution to a concentrate channel of the electrodialysis cell. The tailored aqueous extractant solution includes a tailored concentration of competing monovalent cations. The brine source feed includes a brine concentration of the competing monovalent cations. The tailored concentrations of competing monovalent cations are equal to or higher than the brine concentrations of the competing monovalent cations. The method also includes, resultant from introducing a tailored aqueous extractant solution, reducing transport of competing monovalent cations and enhancing transport of target cation from the brine source. The extractant solution becomes a lithium-concentrated brine.

[0021] Implementations of the invention can include one or more of the following features:

[0022] The brine source can be a geothermal brine.

[0023] The method can further include precipitating the lithium-concentrated brine.Attorney Docket No.: 072174-05101

[0024] The method can further include, resultant from precipitating the lithium-concentrated brine, producing a solid lithium product.

[0025] The lithium product can include Li2CO3 or LiOH·H2O.

[0026] The brine source can include one or more of ions selected from the group consisting of sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chlorine (Cl-), and combinations thereof.

[0027] The brine source can include silica (SiO2).

[0028] The method can include distilling the brine source.

[0029] The method can include introducing a micro-template to the brine source.

[0030] The method can include microfiltering, using the micro-template, the brine source.

[0031] The method can include, resultant from introducing the brine source to an electrodialysis cell, removing divalent cations and anions from the brine source.

[0032] The method can further include, resultant to the distilling, pre-concentrating the lithium using thermal energy in the brine source.

[0033] The distillation and the micro-templating can happen concurrently.

[0034] Introducing the microtemplate can include a ceramic membrane filtration process to remove dissolved silica.

[0035] The method can further include distilling at or below a particular temperature threshold.

[0036] The method can further include resultant from distilling the brine source, introducing the brine source to a ceramic membrane.

[0037] The introducing the brine source to a ceramic membrane can enhance the removal of silica (SiO2).

[0038] The aqueous extractant solution can include concentrations of competing monovalentAttorney Docket No.: 072174-05101 cations the same as or higher than the brine source feed.

[0039] The method can further include introducing a reversed concentration gradient of competing monovalent ions.

[0040] The electrodialysis cell can have alternating feed channels and extractant channels formed between selective cation exchange membranes and anion-exchange membranes.

[0041] The competing monovalent ions can include at least one of sodium (Na+) and potassium (K+).

[0042] The selective hybrid membrane can include a cation exchange layer comprising a polymer having an ion exchange capacity of greater than 0.5 meq / g. The cation exchange membrane can have a thickness of 1 to 200 µm. The selective hybrid membrane can also include a support layer having an average pore size ranging from 1 to 100 nm. The support layer can have a thickness ranging from 10 to 200 µm. The support layer can have a first side and second side, the first side having a smaller pore size than the second layer. The polyamide layer can have a thickness ranging from 5 to 200 nm. The polyamide layer can be situated on the first side of the support layer. The cation exchange layer can be situated on the second side of the support layer. The brine source can include a mixture of two or more cations selected from the group consisting of Li, Na, Ca, Mg, K, Fe, Cu, and Zn. The selective hybrid membrane can be characterized as having at least one of a perm-selectivity of Li+ / Ca2+of greater than 5, and a perm-selectivity of Li+ / Mg2+of greater than 5.

[0043] The selective hybrid membrane can be characterized as having at least one of a perm- selectivity of Li+ / Ca2+of greater than 10 and a perm-selectivity of Li+ / Mg2+of greater than 10.

[0044] The selective hybrid membrane can be characterized as having at least one of a perm- selectivity of Li+ / Ca2+of greater than 20 and a perm-selectivity of Li+ / Mg2+of greater than 30.Attorney Docket No.: 072174-05101

[0045] The selective hybrid membrane can be characterized as having at least one of a perm- selectivity of Li+ / Ca2+of greater than 80 and a perm-selectivity of Li+ / Mg2+of greater than 100.

[0046] The sulfonated polymer can be selected from the group consisting of perfluorosulfonic acid polymers, sulfonated polyolefins, sulfonated polyimides, sulfonated polyamides, sulfonated polyesters, polystyrene sulfonates, sulfonated styrenic block copolymers, sulfonated polyolefins, sulfonated polysulfones, sulfonated polyketones, sulfonated polyphenylene ethers, and mixtures thereof.

[0047] The sulfonated polymer can have a degree of sulfonation of 10 to 100 mol % and an ion exchange capacity of 0.5 to 2.6 meq / g.

[0048] The selective hybrid membrane can include a first layer, a second layer, and a third layer.

[0049] The first layer of the selective hybrid membrane can include a cation exchange polymer.

[0050] The second layer of the selective hybrid membrane can include a porous polysufone membrane.

[0051] The third layer of the selective hybrid membrane can include an ultra-thin polyamide coating.

[0052] The polyamide coating can include LTO.

[0053] The target cation can be Li+.

[0054] In general, in another embodiment, the invention features a lithium selective electrodialysis system to selectively and directly extract lithium from brine source with high efficiency. The system includes a brine source. The system also includes a electrodialysis cell. The cell includes a cathode, an anode, a feed brine channel, an extractant channel, an anolyte channel, an anion- exchange membrane, and a selective cation exchange membrane having a thin film composite structure.Attorney Docket No.: 072174-05101

[0055] Implementations of the invention can include one or more of the following features:

[0056] The brine source can be a geothermal brine.

[0057] The brine source can include one or more of ions selected from the group consisting of sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chlorine (Cl-), and combinations thereof.

[0058] The system can include a multi-effect membrane distillation unit.

[0059] The system can include a micro-template configured to induce polymerization of a material on a surface of the micro-template.

[0060] The system can include a ceramic membrane configured to remove precipitated a material on the surface of the micro-template.

[0061] The brine source can include silica (SiO2).

[0062] The system can further include an aqueous extractant solution. The aqueous extractant solution can include competing monovalent cation concentrations the same or higher than the brine source feed.

[0063] The selective hybrid membrane can include a cation exchange layer comprising a polymer having an ion exchange capacity of greater than 0.5 meq / g. The cation exchange layer can have a thickness of 1 to 200 µm. The selective hybrid membrane can also include a support layer having an average pore size ranging from 1 to 100 nm. The support layer can have a thickness ranging from 10 to 200 µm. The support layer can have a first side and second side, the first side having a smaller pore size than the second layer. The polyamide layer can have a thickness ranging from 5 to 200 nm. The polyamide layer can be situated on the first side of the support layer. The cation exchange layer can be situated on the second side of the support layer. The brine source can include a mixture of two or more cations selected from the group consisting of Li, Na, Ca, Mg, K, Fe, Cu,Attorney Docket No.: 072174-05101 and Zn. The selective hybrid membrane can be characterized as having at least one of a perm- selectivity of Li+ / Ca2+of greater than 5, and a perm-selectivity of Li+ / Mg2+of greater than 5.

[0064] The sulfonated polymer can be selected from the group consisting of perfluorosulfonic acid polymers, sulfonated polyolefins, sulfonated polyimides, sulfonated polyamides, sulfonated polyesters, polystyrene sulfonates, sulfonated styrenic block copolymers, sulfonated polyolefins, sulfonated polysulfones, sulfonated polyketones, sulfonated polyphenylene ethers, and mixtures thereof.

[0065] The sulfonated polymer can have a degree of sulfonation of 10 to 100 mol % and an ion exchange capacity of 0.5 to 2.6 meq / g.

[0066] In general, in one embodiment, the invention features a method of utilizing a fabricated monovalent selective ion exchange membrane for desalination. The method includes forming a polyamide separation layer on the selective ion exchange membrane. The polyamide layer includes one or more polyamides. Each polyamide in the one or more polyamides has a polyamide chemistry. The forming of the polyamide separation layer on the selective ion exchange membrane results in a monovalent / divalent ion separation range. The selective ion exchange membrane includes a first layer comprising an ion exchange polymer, a second layer comprising a middle layer comprising a porous polysulfone membrane, and a third layer comprising the polyamide separation layer. The method also includes tuning the polymide layer to optimize a perm- selectivity of targeted monovalent ions. The target perm-selectivity is determined based on a composition of a brine source. The method also includes introducing the brine source to the monovalent selective ion exchange membrane. The brine source includes the targeted monovalent ions and one or more divalent ions. The method also includes separating the one or more divalent ions from the targeted monovalent ions.Attorney Docket No.: 072174-05101

[0067] Implementations of the invention can include one or more of the following features:

[0068] The introducing the brine source can inclue introducing the brine source in an electrodialysis cell.

[0069] The introducing the brine source in the electrodialysis cell can include introducing the brine source to all flow channels in the electrodialysis cell other than an analyate channel and a catholyte channel.

[0070] In general, in one embodiment, the invention features a monovalent selective ion exchange membrane. The monovalent selective ion exchange membrane includes an ion exchange layer comprising a cation / anion exchange polymer. The monovalent selective ion exchange membrane also includes a support layer. The support layer includes a first side having a first pore size. The support layer includes a second side having a second pore size. The second pore size is larger than the first pore size. The monovalent selective ion exchange membrane also includes a polyamide layer. The polyamide layer is situated on the first side of the support layer. The ion exchange layer is situated on the second side of the support layer. The monovalent selective ion exchange membrane has a perm-selectivity, wherein the perm-selectivity is at least one of a monovalent / divalent perm-selectivity that is greater than 5.

[0071] Implementations of the invention can include one or more of the following features:

[0072] The monovalent ions are Na+and / or Cl-.

[0073] The target permselectivity is determined by composition of the brine source.

[0074] The cation / anion exchange polymer has an ion exchange capacity of greater than approximately 0.5 meq / g.

[0075] The ion exchange layer has an ion exchange membrane thickness in a range between approximately 1 µm and approximately 50 µm.Attorney Docket No.: 072174-05101

[0076] The support layer has an average pore size in a range between approximately 0 nm and approximately 100 nm.

[0077] The support layer has a support layer thickness in a range between approximately 10 µm and approximately 200 µm.

[0078] The polyamide layer has a polyamide layer thickness in a range between approximately 5 nm and approximately 200 nm.

[0079] In general, in one embodiment, the invention features a lithium titanium oxide (LTO) polymerized thin film composite membrane for Li+selection over Na+and Ca2+. The membrane has a Li+ / Ca+selectivity that is greater than 5 and the membrane has a Li+ / Na+selectivity that is greater than 5.

[0080] Implementations of the invention can include one or more of the following features:

[0081] The Li+ / Ca+selectivity can be greater than 50 and the Li+ / Na+selectivity can be greater than 10.

[0082] The LTO polymerized thin film composite membrane is an N-LTO-PA membrane.

[0083] In general, in one embodiment, the invention features a method of making a lithium titanium oxide (LTO) polymerized thin film composite membrane. The method includes selecting LTO particles. The method also includes modifying the LTO particles with -NH2functional groups attached to exposed oxygen sites in the LTO. The method also includes polymerizing the modified LTO particles with a cation exchange base membrane to form the LTO polymerized thin film composite membrane. The membrane has a Li+ / Ca+selectivity that is greater than 5 and the membrane has a Li+ / Na+selectivity that is greater than 5.

[0084] Implementations of the invention can include one or more of the following features:

[0085] The Li+ / Ca+selectivity can be greater than 50 and the Li+ / Na+selectivity can be greaterAttorney Docket No.: 072174-05101 than 10.

[0086] The LTO particles can be LTO nanoparticles.

[0087] The LTO particles can be pre-mixed with trimesoyl chloride (TMC) before the step of polymerization. During the step of polymerization, the cation exchange base membrane can have m-phenylenediamine (MPD) on a surface.

[0088] The LTO polymerized thin film composite membrane can be an N-LTO-PA membrane.

[0089] In general, in one embodiment, the invention features a method that includes selecting a lithium titanium oxide (LTO) polymerized thin film composite membrane having a Li+ / Ca+selectivity that is greater than 5 and the membrane has a Li+ / Na+selectivity that is greater than 5. The method further includes utilizing the LTO polymerized thin film composite membrane as the selective cation exchange membrane to selectively recover lithium in any of the above-described methods for selectively recovering lithium from a brine source.

[0090] In general, in one embodiment, the invention features a system that includes any of the above-described lithium selective electrodialysis system to selectively and directly extract lithium from brine source with high efficiency. The selective cation exchange membrane in the system is a lithium titanium oxide (LTO) polymerized thin film composite membrane having a Li+ / Ca+selectivity that is greater than 5 and the membrane has a Li+ / Na+selectivity that is greater than 5. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Other advantages of the present invention will be apparent from the following detailed description of the invention in conjunction with embodiments as illustrated in the accompanying drawings, in which:

[0092] FIG. 1 depicts a design of a selective hybrid membrane, in accordance with certain embodiments of the present invention.Attorney Docket No.: 072174-05101

[0093] FIG. 2 depicts a schematic of the 3-layer fabrication procedure of the TFC-CEM with morphology changes during fabrication by surface SEMs.

[0094] FIG. 3 shows cross-section SEM images of TFC-CEM with zoomed in image for layer boundaries observation (A1 and A2) inserted with an oriented schematic of the 3-layer structure of TFC-CEM membrane of FIG.1.

[0095] FIGS.4A-4B show characterization an embodiment of TFC-CEM and each layer. FIG. 4A is x-ray photoelectron spectroscopy (XPS) characterization of each layer in TFC-CEM. FIG. 4B is Fourier-Transform Infrared spectroscopy (FTIR) spectra of each layer in TFC-CEM.

[0096] FIGS. 5A-5C show ion permeability tests under diffusive condition, respectively, (A) electrical resistance, (B) the total cation and anion flux, and (C) transport numbers of different cations of commercial CEM, CEP+PSf base membrane, and TFC-CEM.

[0097] FIGS. 6A-6D shows ion permeability test under ED condition. Cation concentration variations with time in extractant chamber when using TFC-CEM and commercial CEM in bi- cation solution with different monovalent / divalent cation pairs: (FIG. 6A) Li+ / Ca2+; (FIG. 6B) Na+ / Ca2+; (FIG.6C) Li+ / Mg2+; (FIG.6D) Na+ / Mg2+.

[0098] FIGS.7A-7D shows ion permeability test of TFC-CEM under ED condition in various of ion molar ratio. Cation concentration variations with time in extractant chamber when using TFC- CEM in bi-cation solution with different monovalent / divalent cation pairs: (FIG. 7A) Li+ / Ca2+; (FIG. 7B) Na+ / Ca2+; (FIG. 7C) Li+ / Mg2+; (FIG. 7D) Na+ / Mg2+. The molar ratio r means monovalent over divalent cation molar ratio, i.e., r=2.5 means 20 mM monovalent and 50 mM divalent cation in feed solution. Monovalent cation concentrations were kept as 20 mM in all experiments. Permeate concentration data for r=1 are retrieved from FIGS.6A-6D.Attorney Docket No.: 072174-05101

[0099] FIGS. 8-9 shows a TFC-CEM mechanism study. FIG. 8 shows monovalent / divalent cation selectivity tested under different ion pairs and ion molar ratios. FIG. 9 shows charge efficiency tested under different ion pairs and ion molar ratios.

[0100] FIGS. 10A-10C show TFC-CEM ion permeation tests in simulated real scenario. FIG. 10A shows an ion molar ratio variation using synthetic brine as feed solution. FIG. 10B shows current density-voltage curves for TFC-CEM using synthetic brine as feed solution. FIG. 10C shows total ion flux with variation of current density.

[0101] FIG. 11 depicts a process diagram of the integrated lithium selective electrodialysis system, in accordance with certain embodiments of the present invention.

[0102] FIGS. 12A-12B show a facile synthesis route of N-LTO-PA layer on base membrane. FIG.12A shows the fabrication route schematic for N-LTO-PA membrane. (The fabrication route of CEP-PSf base membrane is not shown). FIG.12B shows the ball-stick module for evolution of LTO polymerization.

[0103] FIGS. 13A-13F show unique morphology and structure of layered N-LTO-PA membranes. FIG. 13A shows a surface SEM image for synthesized LTO nanoparticles. Size ranging from 45 to 90 nm. FIG.13B shows an SEM image for modified LTO-NH2 particles. FIG. 13C shows surface SEM image for N-LTO-PA membrane. FIG.13D shows EDS mapping images of N-LTO-PA membrane by elements (C, N, O, Ti, Si) with the unmapped image. FIG.13E shows cross-section TEM image of N-LTO-PA layer. FIG.13F shows cross-section SEM images of N- LTO-PA membrane in different scales.

[0104] FIGS. 14A-14G show step by step characteristic validation of polymerized N-LTO-PA membrane. FIG.14A shows XRD pattern for synthesized LTO nanoparticles (peaks matched with standard Li2TiO3 XRD pattern). FIG.14B shows FT-IR pattern comparison between pristine LTOAttorney Docket No.: 072174-05101 and LTO-NH2 nanoparticles. The common peaks for both LTO and LTO-NH2 nanoparticles are marked by shaded belts. Unique peaks appeared in LTO-NH2nanoparticles are marked with arrows in FIG.14B. FIG.14C shows XPS spectra for N-LTO-PA membranes. FIG.14D is the corresponding XPS spectra for C1s in N-LTO-PA membranes. FIG.14E shows EIS analysis for N-LTO-PA membrane with simulated curve, inserted with statical data. FIG. 14F shows chronopotentiometry analysis for limited current density study. FIG. 14G shows FT-IR pattern comparison between pristine PA and N-LTO-PA membrane, the common peaks for both PA and N-LTO-PA membrane are marked by shaded belts.

[0105] FIGS.15A-15B shows Li / Na selectivity achieved by effective LTO adsorbents. FIG.15A shows a schematic of the diffusion cell for an ED reactor. FIG. 15B shows bare LTO bi-solute adsorption test for 3 days. Solution: 20 mL 0.25 g / L LiCl+ 0.25g / L NaCl.

[0106] FIG. 16A-16D show N-LTO-PA realizes Li+ selectivity by tuning Li+ and Na+ transport. . FIGS.16A-16C show (A-B) lithium and sodium concentration variation. FIG.16C shows ion selectivity in extractant chamber using different membranes in tertiary (Li, Na, Ca) solution. FIG. 16D shows flux and selectivity comparison for membranes with different LTO loading

[0107] FIG.17 shows comparison of other CEMs and embodiments disclosed herein in terms of Li+ / Ca2+selectivity and Li+ / Na+selectivity. Each data point represents one published study, except for the data reported herein.

[0108] FIG.18 shows a multi-pair ED cell for lithium extraction using TFC-CEM.

[0109] FIG.19 shows a desalination ED cell for high quality water production containing divalent minerals and scale control in concentrate chamber using TFC-IEM. DETAILED DESCRIPTION

[0110] The present invention relates thin film composite cation exchange membranes and systems and methods thereof, and, more particularly, thin film composite cation exchange membranes forAttorney Docket No.: 072174-05101 monovalent / divalent ion separation in electrodialysis and thin film composite cation exchange membranes for achieving Li separation.

[0111] A novel selective thin film composite cation exchange membrane (TFC-CEM) has been discovered that can achieve desired monovalent / divalent permselectivity. In embodiments, the TFC-CEM contains three layers: a thin cation exchange polymer layer (CEP) for cation / anion separation, a porous middle polysulfone (PSf) layer to provide mechanical strength, and an ultra- thin polyamide (PA) layer to achieve the monovalent / divalent ion separation. Such structure minimizes the electrical resistance of the PA and the support layers. Of import, this membrane structure allows decoupling and independent tuning of different functions of the membrane (i.e., monovalent / divalent separation, cation / anion separation, mechanical strength and ion conduction), which offers a versatile solution to different application needs. The synthesized TFC-CEM provides a superior monovalent / divalent permselectivity, with the Li+ / Ca2+permselectivity of 88.26 achieved even at a Li+ / Ca2+concentration ratio of 1 / 25.

[0112] A novel nano-sized LTO polymerized polyamide cation exchange membrane (n-LTO-PA) has further been discovered, which has application in precise Li selection from brine source. When polymerized on a base cation exchange polysulfone membrane, uniform and high loading of Li selective transport channel generated by LTO rejects other competing cations, leading to a precise selection of Li ions through membrane thus producing very high selectivity. The strong LTO / PA interface and dense LTO layer provided by the n-LTO-PA nexus prevents LTO decomposition and ion leakage from defects, ensuring selective, stable performance of the Li+extraction in the complicated water matrix.Attorney Docket No.: 072174-05101

[0113] The same or similar structure for the cation exchange membranes can be used for anion exchange membranes, such as for use as the anion exchange membranes in desalination applications. Thin Film Composite Cation Exchange Membranes for Monovalent / Divalent Ion Separation in Electrodialysis

[0114] Commercial cation exchange membranes are unable to perform the same charge ions separation needed for extraction technologies essential to a circular economy and clean energy future. Introducing functional layer is an effective modification to differentiate target ions from others, but the performance is varied by membrane types and transport mechanism for multilayer membranes are poorly understood. A thin film composite cation exchange membrane (TFC-CEM) has been discovered for selective monovalent cation permeation in the presence of high divalent cation concentrations. A maximum Na+and Li+selectivity of 136.79 and 119.11 with over 90% of total charge efficiency, respectively, has been found against divalent cations. The fabricated TFC-CEM demonstrates a high monovalent cation selectivity with high energy efficiency and showed great potential for industrial application.

[0115] The present invention provides a lithium selective electrodialysis system to selectively and directly extract lithium from brines with high efficiency, low cost, and minimum waste. Fabrication of Thin Film Composite-Cation Exchange Membrane (TFC-CEM)

[0116] FIG.1 depicts a design of a membrane with a thin film composite structure, in accordance with certain embodiments of the present invention for use with the development of cation exchange membranes with super high monovalent to divalent cation selectivity.

[0117] Lithium extraction processes face problems due to the interference from divalent cations. Specifically, for example in conventional lithium extraction processes, the interference from divalent cations may increase chemical consumption and reduce lithium recovery.Attorney Docket No.: 072174-05101

[0118] As one solution to this problem, in some embodiments, the lithium selective electrodialysis system and method utilize a monovalent selective cation exchange membrane to separate divalent cations from lithium. In such an embodiment, the monovalent selective cation exchange membrane can separate divalent cations from lithium by forming a polyamide separation layer on a cation exchange membrane. In some embodiments, to allow for lithium flux and the complete rejection of divalent cations, a monovalent selective cation exchange membrane, also referred to as selective hybrid membrane, can be utilized.

[0119] In certain embodiments, the selective hybrid membrane can be free standing. In some embodiments, as is shown in FIG. 1, the selective hybrid membrane can have a three-layer thin film composite structure. The first layer 101 may contain a cation exchange polymer with a high ion exchange capacity. The middle layer 102 may be a porous polysulfone membrane to provide mechanical strength and support for the other two functional layers. The porous polysulfone layer may be synthesized using a mature non-solvent induced phase separation process, in certain embodiments. In other embodiments, a commercial ultrafiltration membrane can also be used as the middle layer. The third layer 103 may be an ultra-thin polyamide coating. The ultra-thin polyamide coating may be formed by interfacial polymerization approach to reject divalent ions.

[0120] In preferred embodiments, the selective hybrid membrane is composed of separate layers including a cation or anion exchange polymer layer, a support layer, and a polyamide layer. The thin-film multi-layer structure can allow decoupling of different functions of the membrane. For example, the thin-film multi-layer structure can achieve a wide range of monovalent / divalent separation, cation / anion separation, ion conduction, or combinations thereof. In such embodiments, the thin-film multi-layer structure can therefore allow tuning of each layer’s properties relatively independently, which may optimize each function.Attorney Docket No.: 072174-05101

[0121] The cation exchange polymer layer can include, or consist essentially of, or consist of a polymer having at least one functional group selected from the group consisting of a sulfonic acid, a carboxylic acid, a phosphonic acid, a sulfuric acid ester, a fluorine, and a phosphoric acid ester (a phosphate ester group).

[0122] The anion exchange polymer layer can include a polymer having at least one functional group selected from the group consisting of quaternary ammonium ion, tertiary diamines, (Benz)Imidazolium, Guanidinium, Pyridinium and Metal cations ((Ruthenium, Nickel, Cobalt).

[0123] Sulfonated polymer may refer to polymers having a sulfonate group, such as for example but not limited to, —SO3, either in the acid form (for example, but not limited to, —SO3H or sulfonic acid) or a salt form (for example, but not limited to, —SO3Na). Sulfonated polymer can also refer to sulfonate containing polymers, such as for example, polystyrene sulfonate.

[0124] In some embodiments, the cation exchange polymer layer is based on at least one sulfonated polymer selected from the group consisting of perfluorosulfonic acid polymers (for example, but not limited to, sulfonated tetrafluoroethylene), sulfonated polyolefins, sulfonated polyimides, sulfonated polyamides, sulfonated polyester, polystyrene sulfonates, sulfonated styrenic block copolymers, sulfonated polyolefins, sulfonated polysulfones such as polyether sulfone, sulfonated polyketones such as polyether ether ketone, sulfonated polyphenylene ethers, and mixtures thereof.

[0125] In some embodiments, the sulfonated polymer is characterized as being sufficiently sulfonated, meaning having at least 10 mol % of sulfonic acid or sulfonate ester functional groups based on total mol of the number of monomer units or polymer blocks to be sulfonated (“degree of sulfonation”). In some embodiments, the sulfonated polymer has a degree of sulfonation of at least 10 mol %, or greater than approximately 15, or greater than approximately 20, or greater thanAttorney Docket No.: 072174-05101 approximately 25, or greater than approximately 30, or greater than approximately 40, or greater than approximately 50, or greater than approximately 60, or greater than approximately 70, or greater than approximately 80, or greater than approximately 90, or greater than approximately 99, or approximately 10 – 100, or approximately 20 – 90 mol %. The degree of sulfonation can be calculated by nuclear magnetic resonance or ion exchange capacity.

[0126] In some embodiments, the sulfonated polymer has an ion exchange capacity of at least 0.5, or > 0.75, or > 1.0, or > 1.5, or > 2.0, or > 2.5, or < 5.0 or 0.5 – 3.5, or 0.5 – 2.6 meq / g.

[0127] In some embodiments, the sulfonated polymer is a sulfonated styrenic block copolymer obtained by sulfonation of a styrenic block copolymer precursor which is any of linear, branched, or radial block copolymer having at least one end block A and at least one interior block B.

[0128] In some embodiments, the styrenic block copolymer precursor has a general configuration of: A-B-A, (A-B)n(A), (A-B-A)n, (A-B-A)nX, (A-B)nX, A-D-B, A-B-D, A-D-B-D-A, A-B-D-B- A, (A-D-B)nA, (A-B-D)nA (A-D-B)nX, (A-B-D)nX, (A-D-B-D-A)nX, (A-B-D-B-A)nX or mixtures thereof; where n is an integer from 2 to 30; and X is a residue of a coupling agent (such, for example, alkoxy silanes). Each block A and D is resistant to sulfonation, and each block B is susceptible to sulfonation.

[0129] In some embodiments, the block A can have at least one compound selected from polymerized (i) para-substituted styrene, (ii) ethylene, (iii) alpha olefins of 3 to 18 carbon atoms; (iv) 1,3-cyclodiene, (v) conjugated dienes having a vinyl content of less than 35 mol % prior to hydrogenation, (vi) acrylic esters, (vii) methacrylic esters, and (viii) mixtures thereof. If the block A is a polymer of 1,3-cyclodiene or conjugated diene, the block A will be hydrogenated subsequent to preparation of the styrenic block copolymer and before sulfonation of the styrenic blockAttorney Docket No.: 072174-05101 copolymer precursor. In some embodiments, the block A contains up to 15 wt. % of vinyl aromatic monomers such as those present in the block B.

[0130] In some embodiments, the block A is derived from polymerized para-substituted styrene monomers selected from the group consisting of para-methylstyrene, para-ethylstyrene, para-n- propylstyrene, para-iso-propylstyrene, para-n-butylstyrene, para-sec-butylstyrene, para-iso- butylstyrene, para-t-butylstyrene, isomers of para-decylstyrene, isomers of para-dodecylstyrene, and mixtures thereof.

[0131] In some embodiments, the block B is derived from polymerized vinyl aromatic monomers selected from the group consisting of unsubstituted styrene, ortho-substituted styrene, meta- substituted styrene, alpha-methylstyrene, 1,1-diphenylethylene, 1,2-diphenylethylene, and mixtures thereof. In some embodiments, the block B has a mixture of the vinyl aromatic monomer and hydrogenated conjugated dienes, such as butadiene or isoprene, having a vinyl content, prior to hydrogenation, of 2 – 40, or 5 – 38, or 8 – 35, or 10 – 30, or greater than 5, or less than 40 wt. %, based on total weight of polymerized conjugated diene monomers in the block B.

[0132] In some embodiments, the block D is derived from a polymer or copolymer of a conjugated diene monomer selected from the group consisting of isoprene, 1,3-butadiene, 2,3-dimethyl-1,3- butadiene, 1-phenyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 3-butyl-1,3-octadiene, farnesene, myrcene, piperylene, cyclohexadiene, and mixtures thereof.

[0133] In some embodiments, prior to hydrogenation and sulfonation, the block D has a vinyl content of greater than approximately 80, or greater than approximately 85, or greater than approximately 90, or greater than approximately 95, or greater than approximately 98, or greater than approximately 99, or greater than approximately 99.5, or approximately 50 – 95, orAttorney Docket No.: 072174-05101 approximately 60 – 90, or approximately 70 – 95 wt. %, based on total weight of the polymerized conjugated diene monomers in the block D.

[0134] In some embodiments, the block D has a hydrogenation level of approximately 60 – 99%, or approximately 65 – 95%, or approximately 70 – 90%, or approximately 75 – 99%, or greater than approximately 75%, or greater than approximately 85%, or greater than approximately 95%, or greater than approximately 98%.

[0135] In some embodiments, each block A and B independently has a hydrogenation level of approximately 0 – 20%, or approximately 2 – 18%, or approximately 4 – 15%, or greater than approximately 10%, or greater than approximately 5%, or less than approximately 20%. A suitable catalyst based on nickel, cobalt or titanium can be used in the hydrogenation step.

[0136] The styrenic block copolymer precursor is sulfonated to provide the corresponding sulfonated styrenic block copolymer. In some embodiments, sulfonation occurs at the phenyl ring of polymerized styrene units in the block B, predominantly para to the phenyl carbon atom bonded to the polymer backbone. In some embodiments, the block B has a degree of sulfonation of 10 – 100, or 15 – 95, or 20 – 90, or 25 – 85, or 30 – 80, or 35 – 75, or 40 – 70, or > 15, or < 85 mol %, based on total mol of the block B.

[0137] In some embodiments, the sulfonated polymer is a midblock-sulfonated triblock copolymer, for example, a poly(p‐tert‐butylstyrene‐b‐ styrenesulfonate‐b‐p‐tert‐butylstyrene); or a midblock-sulfonated pentablock copolymer, for example, a poly[tert-butylstyrene-b-(ethylene- alt-propylene)-b-(styrenesulfonate)-b-(ethylene-alt-propylene)-b-tert-butylstyrene.

[0138] In some embodiments, the sulfonated polymer has a molecular weight of 25 – 500, or 30 – 450, or 350 – 400, or 40 – 350, or 45 – 300, or 50 – 250, or > 35, or < 350 kg / mol.Attorney Docket No.: 072174-05101

[0139] In some embodiments, the sulfonated polymer has a glass transition temperature of 80 – 180oC, or 85 – 160oC, or 90 – 150oC, or 100 – 140oC, or > 90oC, or < 210oC, measured by Dynamic Mechanical Analysis, according to ASTM 4065.

[0140] In some embodiments, the sulfonated polymer has a moisture vapor transmission rate of greater than approximately 100, or greater than approximately 500, or greater than approximately 1000 g / m2 / day.

[0141] In some embodiments, the sulfonated polymer has an air permeability of less than approximately 10, or less than approximately 8, or less than approximately 5, or less than approximately 4 g / m2 / day.

[0142] In some embodiments, the sulfonated polymer contains a cross-linked sulfonated polymer obtained by reacting the sulfonated polymer with at least one cross-linking agent selected from the group consisting of acrylates, isocyanurates, aliphatic polyisocyanates, aromatic polyisocyanate, di-isocyanates, polyols such as aliphatic polyester diol, silanes such as alkoxy or vinyl silanes, siloxanes, polyether modified siloxanes, thiols, compounds having two or more vinyl, allyl or isopropenyl groups, anhydrides, and mixtures thereof. In some embodiments, the cross-linking agent is used in amounts of approximately 0.1 – 15, or approximately 0.5 – 12, or approximately 1 – 10, or approximately 2 – 8, or approximately 3 – 7 wt. %, based on total weight of the sulfonated polymer.

[0143] In some embodiments, the sulfonated polymer is a cross-linked sulfonated styrenic block copolymer obtained by cross-linking the sulfonated styrenic block copolymer with a cross-linking agent based on a polyol, for example, polyethylene glycol. The cross-linking can be performed by using radiation or thermal energy for a suitable period to obtain the cross-linked sulfonated styrenic block copolymer.Attorney Docket No.: 072174-05101

[0144] The properties of the sulfonated polymer can be varied and controlled by varying the amount of sulfonation, the degree of neutralization of the sulfonic acid groups to the sulfonated salts, as well as controlling the location of the sulfonated group(s). In some embodiments, the sulfonated polymer is selectively sulfonated for desired water dispersity properties or mechanical properties, for example, having the sulfonic acid functional groups attached to the inner blocks or middle blocks, or in the outer blocks of a copolymer, as described in the Willis ’546 Patent. If the outer (hard) blocks are sulfonated, upon exposure to water, hydration of the hard domains can result in plasticization of those domains and softening, allowing dispersion or solubility.

[0145] In some embodiments, the sulfonated polymer has a general configuration B-D-(D-B)1-5, wherein each block B is a non-elastomeric sulfonated vinyl aromatic polymer block and each block D is a substantially saturated elastomeric alpha-olefin polymer block, said block copolymer being sulfonated to an extent sufficient to provide at least 1% by weight of sulfur in the total polymer and up to one sulfonated constituent for each vinyl aromatic unit.

[0146] Depending on the applications and the desired properties, the sulfonated polymer can be modified (or functionalized). In some embodiments, the sulfonated polymer is neutralized with any of various metal counterions, including alkali, alkaline earth, and transition metals, with at least 10% of the sulfonic acid groups being neutralized. In some embodiments, the sulfonated polymer is neutralized with inorganic or organic cationic salts. For example, the sulfonated polymer is neutralized with inorganic or organic cationic salts based on ammonium, phosphonium, pyridinium, sulfonium, and the like. Salts can be monomeric, oligomeric, or polymeric. In some embodiments, the sulfonated polymer is neutralized with various primary, secondary, or tertiary amine-containing molecules, with greater than 10% of the sulfonic acid or sulfonate ester functional groups being neutralized.Attorney Docket No.: 072174-05101

[0147] In some embodiments, the monomer or the block containing amine functionality or phosphine functionality is neutralized with acids or proton donors, creating quaternary ammonium or phosphonium salts. In other embodiments, the sulfonated polymer containing tertiary amine is reacted with alkylhalides to form functional groups, for example but not limited to, quaternized salts. In some embodiments, the sulfonated polymer contains both cationic and anionic functionality to form zwitterionic polymers.

[0148] In some embodiments, the sulfonic acid or sulfonate functional group can be modified by reaction with an effective amount of polyoxyalkyleneamine having molecular weights from 140 to 10,000. Amine-containing neutralizing agents can be mono-functional or multi-functional; monomeric, oligomeric, or polymeric. In alternative embodiments, the sulfonated polymer is modified with alternative anionic functionalities, such as phosphonic acid or acrylic and alkyl acrylic acids.

[0149] In some embodiments, amine containing polymers can be used for the modification of the sulfonated polymers, forming members of a class of materials termed coaservates. Examples of the neutralizing agents include a polymeric amine, for example, polymers containing benzylamine functionality, or homopolymers and copolymers of 4-dimethylaminostyrene which has been described in the Masel ’450 Patent. In some embodiments, the neutralizing agents are selected from polymers containing vinylbenzylamine functionality, for example, polymers synthesized from poly-p-methylstyrene containing block copolymers via a bromination-amination strategy, or by direct anionic polymerization of amine containing styrenic monomers. Examples of amine functionalities for functionalization include p-vinylbenzyldimethylamine (BDMA), p- vinylbenzylpyrrolidine (VBPyr), p-vinylbenzyl-bis(2-methoxyethyl)amine (VBDEM), p- vinylbenzylpiperazine (VBMPip), and p-vinylbenzyldiphenylamine (VBDPA). CorrespondingAttorney Docket No.: 072174-05101 phosphorus containing polymers can also be used for the functionalization of the sulfonated polymers.

[0150] In some embodiments, the cation exchange polymer layer can further contain at least one other polymer other than the sulfonated polymer. Examples of other polymers include polytetrafluoroethylenes (PTFEs), polyolefins, polyimides, polyamides, polyesters, polystyrenes, polysulfones, polyketones, polyphenylene ethers, polyisoprenes, polybutadienes, polyvinylidene fluorides, polycarbonates, polyetherimides, ethylene-vinyl alcohol copolymers, polyvinylidene chlorides, polyacrylates, polytertbutylstyrene, and mixtures thereof, in amounts of approximately 1 – 30, or approximately 2 – 25, or approximately 5 – 20 wt. %, based on total weight of the cation exchange polymer layer.

[0151] In some embodiments, the selective hybrid membrane further comprises at least one additive including but not limited to activators, curing agents, stabilizers, neutralizing agents, thickeners, coalescing agents, slip agents, antimicrobial agents, surfactants, antioxidants, antiozonants, color change pH indicators, plasticizers, tackifiers, film forming additives, dyes, pigments, UV stabilizers, UV absorbers, catalysts, fillers, other resins, redox couples, fibers, flame retardants, viscosity modifiers, wetting agents, deaerators, toughening agents, adhesion promoters, colorants, heat stabilizers, lubricants, flow modifiers, drip retardants, antistatic agents, processing aids, stress-relief additives, and mixtures thereof. Additives can be added into the cation exchange polymer layer in an amount of approximately 0.5 – 25, or approximately 1 – 20, or approximately 2 – 15, or approximately 0.5 – 10, or approximately 0.5 – 5 wt. %, based on total weight of the cation exchange polymer layer.Attorney Docket No.: 072174-05101

[0152] In some embodiments, the cation exchange polymer layer has a thickness of approximately 1 – 50 µm, or approximately 5 – 40 µm, or approximately 5 – 30 µm, or approximately 10 – 45 µm, or approximately 1 – 25 µm.

[0153] In some embodiments, the selective hybrid membrane may contain one or more cation exchange polymer layers, same or different from each other, based on desired setup for extraction of lithium from the feed. Further, in some embodiments, the electrodialysis cell may contain one or more selective hybrid membranes, same or different from each other, based on desired setup for extraction of lithium from the feed.

[0154] In some embodiments, the support layer may have a gradient of pore sizes across the thickness of the selective hybrid membrane. In certain embodiments, the support layer may contain plurality of pores with an average pore size of approximately 0.1 – 100 nm, or approximately 0.5 – 50 nm, or approximately 1 – 50 nm, or approximately 20 – 100 nm, or approximately 5 – 50 nm, or approximately 40 – 80 nm. In some embodiments, the support layer has a pore volume of approximately 30 – 80%, or approximately 40 – 70%, or approximately 50 – 80%, or approximately 40 – 65%, or greater than approximately 40%, or greater than approximately 50%, or greater than approximately 60%. In some embodiments, the pores have an aspect ratio of 0.5:1 to 20:1, or 1:1 to 5:1, or 1:1 to 10:1, or 1:1 to 15:1.

[0155] In some embodiments, the support layer has a thickness of 10 – 200 µm, or 20 – 150 µm, or 30 – 130 µm, or 50 – 200 µm, or 80 – 160 µm, or 70 – 140 µm.

[0156] In some embodiments, the support layer may include a polymer selected from the group of: polyimide, polyether ether ketone (PEEK), polybenzimidazole, sulfonated tetrafluoroethylene, polysiloxane, polyurethane, polycarbonate, polyethyleneimine, polyester, polyamide, polysulfone, polyethersulfone, polyvinylchloride, polyethylene, polypropylene, fluoropolymer, polyvinylideneAttorney Docket No.: 072174-05101 fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethersulfone, cellulose acetate, ultrahigh molecular weight polyethylene (UHMW-PE), polycaprolactam, poly(hexamethylene adipamide), and mixtures thereof.

[0157] The support layer, in preferred embodiments, may have at least a first surface and at least a second surface.

[0158] In some embodiments, the support layer may include a polysulfone in amounts of up to 100 wt. %, or approximately 90 – 99, or approximately 90 – 95 wt. %, based on total weight of the support layer. The polysulfone can be selected from an aromatic polysulfone, an aliphatic polysulfone, or mixtures thereof. In some embodiments, the polysulfone has a molecular weight of 5 – 500, or 10 – 300, or 50 – 200, or 10 – 50, or 20 – 120 kg / mol. In embodiments, the polysulfone has a compressive strength of 0.25 – 1.00, or 0.30 – 0.90, or 0.35 – 0.85, or 0.40 – 0.80, or 0.30 – 0.70 MPa.

[0159] In embodiments, the selective hybrid membrane contains at least one support layer. In some embodiments the selective hybrid membrane may contain multiple support layers, the same or different from each other, assembled together.

[0160] In embodiments, the support layer is acid resistant and thermally stable at a temperature of greater than approximately 50oC, or greater than approximately 70oC, or greater than approximately 90oC, or greater than approximately 100oC, or greater than approximately 120oC, or greater than approximately 150oC, or less than approximately 250oC.

[0161] The third layer 103 may be an ultra-thin polyamide coating. The ultra-thin polyamide coating may be formed by interfacial polymerization approach with various polyamide chemistries to achieve a range of monovalent / divalent ion separation. Depending on the feed water composition and the desired end use of the desalinated product water, in some embodiments, theAttorney Docket No.: 072174-05101 monovalent / divalent permselectivity can be tuned by tuning the chemistry used to form the ultrathin polyamide layer, such as the type of monomers, reaction conditions, porosity and hydrophilicity of the substrate, and other variables used in the interfacial polymerization process.

[0162] In some embodiments, a polyamide layer may include a polyamide selected from the group consisting of aliphatic polyamides, aromatic polyamides, and mixtures thereof.

[0163] In some embodiments, the polyamide layer can be formed by interfacial polymerization of at least one multifunctional acid halide and at least one multifunctional amine on at least one surface of the support layer. Examples of the multifunctional acid halide include phthaloyl (such as, but not limited to, isophthaloyl or terephthaloyl) halide, trimesyl halide, trimesoyl halide (such as, but not limited to, trimesoyl chloride), trimellitoyl-halide, pyromellitoyl halide, benzophenonetetracarbonyl halide, diphenyldicarbonyl halide, naphthalenedicarbonyl halide, benzenedisulfonyl halide, chlorosulfonylisophthaloyl halide, pyridinedicarbonyl halide, 1,3,5- cyclohexanetricarbonyl halid, and mixtures thereof. Examples of the multifunctional amine include diaminobenzene, triaminobenzene, polyetherimine, piperazine, poly-piperazine, 2- ethylpiperazine, 2,5-dimethylpiperazine, homopiperazine, t-2,5-dimethylpiperazin, m- phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenylamine, 3,5-diaminobenzoates, 4,4'- diaminodiphenylsulfone, 3,3'- diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 1,3, 5- triaminobenzene, bis(4-piperidyl)methane, 1,2-bis(4-piperidyl)ethane, 1,3- bis(4- piperidyl)propane, N,N'-dimethylethylenediamine, ethylenediamine, propylenediamine, propylenetriamine, N,N'-dimethylpropanediamine, 4-(aminomethyl)piperidine, cyclohexanediamine, and mixtures thereof.Attorney Docket No.: 072174-05101

[0164] In an embodiment of interfacial polymerization, solutions of multifunctional acid halide and multifunctional amine are prepared separately in a solvent. In some embodiments, the multifunctional acid halide does not have low solubility in the multifunctional amine and the multifunctional amine does not have low solubility in the multifunctional acid halide. The solvent is not limited, so long as it dissolves the multifunctional amine and the multifunctional acid halide, forming a liquid-liquid interface when these solutions are brought into contact with each other on the support layer. Water can be used as the solvent to dissolve the multifunctional amine. Solvents for the multifunctional acid halide include, for example, hydrocarbon solvents such as n-hexane, cyclohexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, and mixtures thereof.

[0165] The concentrations of the multifunctional acid halide and the multifunctional amine in respective solvents are based on their types and distribution coefficients with respect to solvents. The concentration of the multifunctional amine can be from approximately 0.1 – 20%, or approximately 0.5 – 10%, or approximately 1 – 15%, or approximately 1 – 10 %, and the concentration of multifunctional acid halide can be from approximately 0.1 – 20%, or approximately 0.5 – 10%, or approximately 1 – 15%, or approximately 1 – 10%. In certain embodiments, a weight ratio of the multifunctional amine to the multifunctional acid halide is 20:1 – 0.1:1, or 10:1 – 0.5:1, or 5:1 – 1:1. The multifunctional amine solution, the multifunctional acid halide solution, or combinations thereof can be independently heated to a temperature in the range of approximately 5 – 50oC, or approximately 10 – 45oC, or approximately 15 – 40oC, or approximately 20 – 50oC, or approximately 10 – 40oC, or approximately 20 – 45oC.

[0166] In some embodiments, the multifunctional amine solution, the multifunctional acid halide solution, or combinations thereof may further include at least one additive in a suitable amount. Examples of additives include acid acceptors, surfactants, reaction accelerators, and mixturesAttorney Docket No.: 072174-05101 thereof. In some embodiments, additives are used during the polyamide synthesis, such as for example but not limited to Triethylamine, (±)-camphor-10-sulfonic acid, dimethyl sulfoxide, sodium dodecyl sulfate, and acetone.

[0167] In certain embodiments, the process of interfacial polymerization involves immersing the support layer in the multifunctional amine solution, then bringing the support layer (with multifunctional amine solution) into contact with the multifunctional acid halide solution to perform interfacial polymerization. In other embodiments, the process of interfacial polymerization can involve casting a thin layer of the amine solution on the surface of the support layer.

[0168] After polymerization, in some embodiments, the support layer is thoroughly washed to remove chemicals in the support layer and then subsequently dried, thereby obtaining a polyamide layer on the support layer.

[0169] In embodiments, the polyamide layer has a thickness of approximately 5 – 200 nm, or approximately 10 – 100 nm, approximately 20 – 120 nm, or approximately 30 – 150 nm, or approximately 40 – 140 nm, or approximately 50 – 120 nm.

[0170] In some embodiments, in accordance with the discussion below in respect to FIG. 4, the selective ion exchange membrane may be used for desalination processes.

[0171] Accordingly, in some embodiments, a monovalent selective ion exchange membrane is utilized to separate divalent cations from targeted monovalent ions. In such an embodiment, the monovalent selective ion exchange membrane can separate divalent cations from targeted monovalent ions by forming a polyamide separation layer on an ion exchange membrane.

[0172] The middle layer 102 may be a porous polysulfone membrane to provide mechanical strength and support for the other two functional layers. The porous polysulfone layer may beAttorney Docket No.: 072174-05101 synthesized using a mature non-solvent induced phase separation process, in certain embodiments. In other embodiments, a commercial ultrafiltration membrane can also be used as the middle layer.

[0173] The cation exchange polymer layer can include a polymer having at least one functional group selected from the group consisting of a sulfonic acid, a carboxylic acid, a phosphonic acid, a sulfuric acid ester, a fluorine, and a phosphoric acid ester (a phosphate ester group).

[0174] In some embodiments, the ion exchange polymer layer has a thickness of approximately 1 – 50 µm, or approximately 5 – 40 µm, or approximately 5 – 30 µm, or approximately 10 – 45 µm, or approximately 1 – 25 µm.

[0175] In an embodiment of interfacial polymerization, solutions of multifunctional acid halide and multifunctional amine can be prepared separately in a solvent. In some embodiments, the multifunctional acid halide does not have low solubility in the multifunctional amine and the multifunctional amine does not have low solubility in the multifunctional acid halide. In such an embodiment, the solvent is not limited, so long as it dissolves the multifunctional amine and the multifunctional acid halide, forming a liquid-liquid interface when these solutions are brought into contact with each other on the support layer.

[0176] Water can be used as the solvent to dissolve the multifunctional amine in some embodiments. Solvents for the multifunctional acid halide can include, for example, hydrocarbon solvents such as n-hexane, cyclohexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, and mixtures thereof.

[0177] The concentrations of the multifunctional acid halide and the multifunctional amine in respective solvents can be based on their types and distribution coefficients with respect to solvents. The concentration of the multifunctional amine can be from approximately 0.1 – 20%, or approximately 0.5 – 10%, or approximately 1 – 15%, or approximately 1 – 10 %, and theAttorney Docket No.: 072174-05101 concentration of multifunctional acid halide can be from approximately 0.1 – 20%, or approximately 0.5 – 10%, or approximately 1 – 15%, or approximately 1 – 10%. In certain embodiments, a weight ratio of the multifunctional amine to the multifunctional acid halide is 20:1 – 0.1:1, or 10:1 – 0.5:1, or 5:1 – 1:1. The multifunctional amine solution, the multifunctional acid halide solution, or combinations thereof can be independently heated to a temperature in the range of approximately 5 – 50oC, or approximately 10 – 45oC, or approximately 15 – 40oC, or approximately 20 – 50oC, or approximately 10 – 40oC, or approximately 20 – 45oC.

[0178] In some embodiments, the multifunctional amine solution, the multifunctional acid halide solution, or combinations thereof may further include at least one additive in a suitable amount. Examples of additives include acid acceptors, surfactants, reaction accelerators, and mixtures thereof.

[0179] In certain embodiments, the process of interfacial polymerization involves immersing the support layer in the multifunctional amine solution, then bringing the support layer (with multifunctional amine solution) into contact with the multifunctional acid halide solution to perform interfacial polymerization. In other embodiments, the process of interfacial polymerization can involve casting a thin layer of the amine solution on the surface of the support layer.

[0180] After polymerization, in some embodiments, the support layer is thoroughly washed to remove chemicals in the support layer and then subsequently dried, thereby obtaining a polyamide layer on the support layer.

[0181] In certain embodiments, the polyamide layer has a thickness of approximately 5 – 200 nm, or approximately 10 – 100 nm, approximately 20 – 120 nm, or approximately 30 – 150 nm, or approximately 40 – 140 nm, or approximately 50 – 120 nm.Attorney Docket No.: 072174-05101

[0182] Accordingly, from the description above, the monovalent selective ion exchange membrane can be used in an electrodialysis system for cost-effective water desalination with largely reduced scaling potential and desirable product water quality depending on end use such as for drinking and agricultural application.

[0183] Further, accordingly, the monovalent selective ion exchange membrane can be used in an electrodialysis system for resource recovery such as lithium extraction from lithium-containing water.

[0184] The monovalent selective ion exchange membrane can be used in an electrodialysis system for wastewater treatment to have enhanced nitrate removal and recovery.

[0185] In a representative embodiment, a thin film composite-cation exchange membrane (TFC- CEM) was fabricated as follows. The fabrication of TFC-CEM contains three steps including the fabrication of polysulfone (PSf) substrate, the coating of CEM, and the polyamide (PA) synthesis. The detailed fabrication processes are as follows and are shown in the schematic of fabrication of FIG.2.

[0186] Detailed information of commercial membranes and MD 9200 polymer are further provided in TABLE I. TABLE I Nominal Membrane Properties Exchan e Membrane Water

[0187] The fabrication of PSf. The PSf membrane was prepared using non-solvent induced phase separation (NIPS) technique (process 201). The polymer cast solution was prepared by mixing 15 wt% PSf, 8 wt% PVP and 77 wt% NMP for 24 h at 50℃ and then stored in the dark overnight toAttorney Docket No.: 072174-05101 remove all the air bubbles. The cast solution was heated to 60 °C in a water bath, casted onto a dry and clean glass plate (DP-GB-2B, Paul N. Gardner, USA) to form a liquid film with a thickness of about 200 μm using a blade applicator (AP-G06 / 10, Paul N. Gardner, USA). The glass plate was then quickly placed into a coagulation (water) bath of 60 °C for 20 min. SEMS 206a-206c show the fabricated PSf.

[0188] Coating of MD9200 cation exchange polymer (CEP) layer. The bottom surface of PSf which has larger pores was prewetted by the mixture of EtOH / DI (v / v=1:3). A layer of MD9200 was cast on the bottom surface of PSf by a flow coater at a solution loading of 200 uL / cm2and a casting speed of 1cm / s (process 202). The cast membrane was air dried for 4 hours in the fume hood. SEM 207 show the CEP layer.

[0189] PA synthesis. After the coating of CEM, a thin PA layer was synthesized on the top surface of PSf via the optimized interfacial polymerization.The top surface of PSf was in contact with 20 mL of 2.0 wt% MPD aqueous solution for 3 min (process 203). Thereafter, the excess MPD was removed and the top surface of PSf was immersed in the 2 mL of 0.2 wt% of TMC in n-hexane for 30 s (process 204). After rinsed by n-hexane solution the membrane was dried and cured at 60℃ for 10 min (process 205). SEM 208 show the PA layer. Characterization Of TFC-CEM

[0190] For this fabricated TFC-CEM, the surface morphology of PSf before and after different coating processes were thoroughly characterized by SEM. The white PSf middle layer was fabricated via NIPS method and several holes are cut around boundary for better mounting in ED cell (SEM 206a). Before coating, the synthesized PSf exhibited different pore sizes on the top side (SEM 206b) and bottom side (SEM 206c), which were about 50 nm and several micrometers, respectively. After the coating of CEP on the PSf bottom side, a uniform and dense layer of CEPAttorney Docket No.: 072174-05101 was observed on the surface as no big pores were spotted. However, different morphology was observed on the other side of membrane. After the interfacial polymerization of PA coating on the PSf top side, a rough dense layer was formed with a typical ridge-and-valley structure, which indicating the successful coating of a PA layer.

[0191] As expected, the cross-section of TFC-CEM was characterized as a three-layer composite, which were the CEP layer, the PSf support middle layer and a thin PA layer from top to bottom. See SEM 301 of FIG.3. SEM 302 (A1) shows a zoomed in image for layer boundary between the CEP layer and the PSf support middle layer. SEM 303 (A2) shows a zoomed in image for layer boundary between the PSf support middle layer and the thin PA layer. The orientation of the layers of TFC-CEM (illustrated in FIG.1) is shown in illustration 304.

[0192] The CEP strongly bonded to PSf, forming a dense layer with a thickness of 19.8 um. The PSf middle layer, with a thickness of 109.0 um, showed an asymmetric porous structure composed of large finger-like voids and a thin selective layer, which was typical of the phase inversion process. At the selective layer side, a thin coating of PA layer was observed, and the thickness was too small to be characterized by the SEM.

[0193] Additionally, the chemical composition of each layer was further confirmed by the XPS and the FTIR. FIGS.4A-4B. In XPS spectrum, the characteristic element S was detected in both CEP and PSf layers, which were attributed to the sulfonate and the sulfonyl functional groups. N was detected in the PA layer, indicating the existence of the amide groups. Moreover, the specific functional groups in each layer were also confirmed by FTIR.

[0194] Low electrical resistance can be essential for membranes used in electrified field aiming at low electricity costs. As shown in FIG. 5A, TFC-CEM demonstrated comparable electrical resistance with the commercial CEMs. The electrical resistance of TFC-CEM in 0.1 M NaClAttorney Docket No.: 072174-05101 solution obtained from EIS analysis was 6.8 Ω cm2while CR62-T CEM from Veolia and Type-II CEM from FUJIFILM were 6.5 and 8.0 Ω cm2, respectively. The simulation result revealed that TFC-CEM exhibited similar electric resistance to commercial products.

[0195] Additionally, the synthesized TFC-CEM can be used as a cation exchange membrane, as the permselectivity of cation over anion was 29.18, indicating the preferential transport of cations by TFC-CEM. FIG. 5B. However, the cation / anion separation performance of TFC-CEM was less comparable to that of commercial CEM, which was due to the less exchange capacity of much thinner CEP layer in the TFC-CEM. In the TFC-CEM, only the 20 μm CEP layer was effective for the cation / anion separation, which was much thinner than the 420 μm commercial CEM. Ion Permeability Test Of TFC-CEM

[0196] To evaluate the selective ion transport performance of different membranes, TFC-CEM and commercial CEMs were first conducted via diffusive ion permeability test in the two- compartment cell to separate solutions dissolving 0.1 and 0.2 mol L-1chlorine salts with various cations. After 10 minutes of diffusion, membrane potential was measured and transport number for cations were calculated. The transport number of varied cations of different membranes are shown in Error! Reference source not found.5C.

[0197] For commercial CEM, the transport numbers of all the cations are similar and larger than 0.91. Transport numbers of monovalent ions (TNNa+=0.93; TNK+=0.99; TNLi+=0.96) are only slightly higher than the divalent ions (TNCa2+=0.92; TNMg2+=0.91), indicating the preferential transportation of monovalent ions but with very little selectivity, which may due to smaller hydrated ion radius of monovalent cations. Similarly, TFC-CEM without PA coating (CEP+PSf) exhibited no monovalent / divalent ion selectivity as no obvious difference in ion transport numbers,Attorney Docket No.: 072174-05101 which proved CEP and PSf layers possesses no contribution to mono / divalent cation selectivity. FIG.5C.

[0198] As a comparison, for TFC-CEM which has the PA layer, the transport numbers of all cations are smaller than that of commercial CEM and CEP+PSf membrane. Of import, distinctive difference in transport numbers was determined between monovalent and divalent ions. For example, the transport numbers of Li+and Na+were 0.90 and 0.84 while same parameter for Ca2+and Mg2+were only 0.53 and 0.56, respectively, indicating the intrinsic Li+ / Ca2+permselectivity of the synthesized TFC-CEM. The difference between TFC-CEM and CEP+PSF membrane also revealed that the monovalent / divalent selectivity of TFC-CEM is attributed to the PA layer. The PA layer in TFC-CEM by interfacial polymerization is like the active separation layer in the NF membranes. It was surprising to see a very low TN for divalent cations in a cation exchange membrane, which normally possesses a higher TN of >0.9. The low TN is believed to be due to the unique asymmetric structure of TFC-CEM that PA layer is proven to reject more larger Ca2+than Cl- ions so anions, even with resistance from PA, were accumulated in higher concentration than Ca2+before passing through the CEP layer. By compressing the double layer of CEP by a higher accumulated concentration adjacent to the CEP interface, anions permeation increased, and total ion flux was higher than Ca2+thus contributed more into total current, which led to a low TN for divalent cations and consequently high TN for anions. The slight difference between Ca2+can Mg2+also confirmed this belief due to a larger hydrated radius of Mg2+than Ca2+. While in conventional CEMs, anions were facing consistent resistance throughout the whole CEM while Ca2+ions are preferably transported so that more than half of current was carried by cations. Further discussion regarding the structure of TFC-CEM is provided hereinafter.Attorney Docket No.: 072174-05101

[0199] Ion permselectivity of commercial CEM and TFC-CEM in a mixed solution were tested and evaluated using the 3-chamber ED system with four pairs of monovalent / divalent cations contained solution tested in feed chamber. Under the electrical field with a current density of 0.24 mA / cm2, Ion concentrations of cations are shown in FIGS. 6A (with plots 601-604 for Comm CEM Li, Comm CEM Ca, TFC-CEM Li, and TFC-CEM Ca, respectively), FIG.6B (with plots 611-614 for Comm CEM Na, Comm CEM Ca, TFC-CEM Na, and TFC-CEM Ca, respectively), FIG.6C (with plots 621-624 for Comm CEM Li, Comm CEM Mg, TFC-CEM Li, and TFC-CEM Mg, respectively), and FIG.6D (with plots 631-634 for Comm CEM Na, Comm CEM Mg, TFC- CEM Na, and TFC-CEM Mg, respectively).

[0200] Cations were transported by electric field through the membrane as a simultaneous variation of cation concentration was observed in the feed and permeate chamber. Regardless of ion pairs, all tests exhibited similar trends for all cation pairs when using commercial CEMs, which divalent cations were dominated ions in during transportation. For example, the largest difference was observed in Li+ / Ca2+pair, where 1.13 mmol L-1of Ca2+but only 0.26 mmol L-1of Li+were detected in extractant chamber after 2 hours experiment. Commercial CEM demonstrated the preferential transport of Ca2+over Li+, indicating no monovalent / divalent permselectivity. It is similarly anticipated in the non-selective CEMs with sulfonic groups, which have higher affinity towards divalent than monovalent cations.

[0201] In addition, higher-valence cations exhibit enhanced electrophoretic mobility under electrical field thus stronger driving force assisted Ca2+than Li+. Divalent cations in other groups also achieved 1.04, 1.01, and 0.96 mmol L-1in extractant concentration during other ion pair tests while monovalent cations like Na+and Li+only achieved 0.37, 0.34, and 0.51 mmol L-1.Attorney Docket No.: 072174-05101 Considering that the commercial CEM is made by ion exchange resins, the observed transport rate results were consistent with reported study by using resins.

[0202] In contrast, the synthesized TFC-CEM demonstrated significantly enhanced monovalent / divalent permselectivity as the monovalent cation flux was greatly increased and the divalent flux was inhibited under constant current density. Due to size exclusion and Donnan exclusion effect provided by PA layer, Ca2+is reduced by 87.6% and only 0.14 mmol L-1of Ca2+was transported through the TFC-CEM to the concentrate channel after 2 hours in the Li / Ca selecvitiy experiment. In contrast, more Li+ions crossed membrane thus concentration increased over 8 times to 2.09 mmol L-1. Similarly, in Na / Ca selectivity test, Na+reached 2.33 mmol L-1while 0.12 mmol L-1Ca2+was measured in the concentrate chamber. Similar results were observed in Na / Mg (2.47 mmole L-1Na+and 0.113 mmol L-1Mg2+) and Li / Mg selectivity (2.15 mmol L-1Li+and 0.110 mmol L-1Mg2+) experiments.

[0203] Permselectivity of TFC-CEM was further investigated by calculating the ion flux. As divalent cations dominated the transport as discussed above, the monovalent / divalent permselectivity P1+ / 2+ are around 0.23~0.53 when using commercial CEM to test various ion pairs. See TABLE II. TABLE II Permselectivity Of Commercial CEM Tested By Various Ion Pairs Ion pair Li / Ca Na / Ca Li / Mg Na / Mg -1 -2

[0204] However, the permselectivity increased by nearly 100 times when switching to TFC-CEM as P1+ / 2+ ranging from 14.21 to 20.88 due to selective PA layer coated on membranes. The highestAttorney Docket No.: 072174-05101 P1+ / 2+ for both membranes were found when testing Na / Mg ion pair, and the lowest P1+ / 2+ were found when testing Na+and Ca2+ion pair. The Mechanism Of Monovalent / Divalent Cation Selectivity The Impact Of Ion Molar Ratios

[0205] According to the Nerst-Planck equation, ion flux is determined by multiple factors including ion concentration. As a selective layer that provides most of resistance towards ions, the overall ion flux during ED process is generally limited by ion flux across the CEM. Similarly, cross-membrane ion flux is affected by ion concentration in membrane phase, which is drastically influenced by ion concentration in bulk solution phase. Investigating the effect of bulk solution ion concentration towards ion selectivity has import to mimic actual performance of TFC-CEM in ED process when using real water samples. Four representative divalent cation concentrations at 20 mmol L-1, 50 mmol L-1, 200 mmol L-1, and 500 mmol L-1while fixing monovalent ion concentration at 20 mmol L-1have been tested to evaluate monovalent cation selectivity of TFC- CEM. The divalent / monovalent molar ratio of tested solutions (shortened as r in herein, including within the figures) ranging from 1, 2.5, 10, to 25 covered ratios spotted in high concentration divalent cation existed water resources like sea water and geothermal brine. Similar with ion permeability test, four (4) representative ion pairs have been tested in 2-hour ED tests. As shown in FIG.7A (with plots 701-704 for r=1, 2.5, 10, and 25 Li, respectively, and plots 705- 708 for r=1, 2.5, 10, and 25 Ca, respectively), FIG.7B (with plots 711-714 for r=1, 2.5, 10, and 25 Na, respectively, and plots 705-708 for r=1, 2.5, 10, and 25 Ca, respectively), FIG.7C (with plots 721-724 for r=1, 2.5, 10, and 25 Li, respectively, and plots 725-728 for r=1, 2.5, 10, and 25 Mg, respectively), and FIG.7D (with plots 731-734 for r=1, 2.5, 10, and 25 Na, respectively, and plots 735-738 for r=1, 2.5, 10, and 25 Mg, respectively), monovalent / divalent selectivity have beenAttorney Docket No.: 072174-05101 observed in all tests that Na+and Li+showed significant concentration increases that over 1.5 mmol L-1for 2 hours while divalent cations concentration is sluggishly raised below 0.5 mmol L-1. See TABLE III. TABLE III Permselectivity Of TFC-CEM Tested By Various Ion Molar Ratios r=1 Li / Ca Na / Ca Li / Mg Na / Mg Monovalent concentration (mmol L-1) 2.09 2.34 2.15 2.48 g g g[ ] orrespon ng y, e ne c an e c ency s u y was a so con uc e or mo ar ratio studies and shown in FIG. 8. Consistent to permeability, ion flux of monovalent and divalent cations varied reversely when divalent cation initial concentration raised up to 25 times higher than monovalent cations. Monovalent flux can be maintained 3.5-5.5 times higher than divalent flux even under in the most extreme condition when r=25.Attorney Docket No.: 072174-05101

[0207] Monovalent / divalent selectivity is a uniform indicator to express preferential transport of target ions over competing ions thus calculated selectivity under different molar ratios were shown in FIG.9. It is interesting that increased trend of selectivity was observed when raising ion molar ratio since higher divalent cation concentration would generally enhance divalent cation flux. The increased selectivity is due to concentration-independent resistance of PA layer that maintain significant rejection to ions regardless of ion concentration variation in bulk solutions. Although higher concentration gradient was created when r was raising thus enhancing diffusion across the membrane, the PA layer on TFC-CEM also rejected much more divalent cations so that divalent ion flux was not increased proportionally or higher with r. For instance, Ca2+exhibited an ion flux of 4.333 mmol L-1when r=1 and same parameter increased over 2.5 times to 10.844 mmol L-1when 10 times Ca2+existed in feed solution. However, selectivity was calculated by dividing the ion ratio from ion flux ratio so that PLi+ / Ca2+, r=1is 14.21 while PLi+ / Ca2+ r=10is 46.95, which is increased by 10 times higher Li / Ca molar ratio even the Li / Ca ion flux ratio was reduced 3 times from 14.2 to 4.7. Notably, charge efficiency analysis for ion pairs has shown a well-maintained mass balance process without leakage and the tiny loss of charges may be due to adsorption of ions in membrane. FIG.9. The increase of divalent cation CEs with higher r were due to enhanced transport by concentration and consequently reduced monovalent cation CE were by fixed current density. The Impact Of Asymmetric Membrane Structure

[0208] Unlike commercial ion exchange membranes with uniform and symmetric structures within the whole membrane, the TFC-CEM possesses an asymmetric layered structure that transports ions across layers with different charge density, porosity, and morphology. Symmetric structure leads to identical transport performance regardless of membrane faces since ionAttorney Docket No.: 072174-05101 concentration profile changed similarly when place faces of membrane to solutions. It was hypothesized by Applicant that asymmetric structure would lead to a different permeation with different layer orders in membrane.

[0209] When PA layer was faced with feed in same concentration of Li and Ca ions, PA is preferably pass through Li+but reject Ca2+so that more Li+than Ca2+are transported to the middle PSf layer. The PSf layer is assumed to exhibit negligible resistance to ions since bare PSf membranes are widely used in microfiltration and ultrafiltration processes, which has no rejection to ions due to large pore size. Thus, concentration profile for ions remained the same when across the PSf layer till reached CEP-PSf interface.

[0210] Although ion permeation through CEP has not been individually investigated, it is reasonable to predict ion behavior in CEP layer based on observation and discussions of commercial CEM because of similar structure and same fixed functional groups. According to previous results, divalent cations transport under electric field is preferred in commercial CEM, so that Ca2+might permeate more rapidly than Li+through CEP. However, in terms of Ca2+permeation the enhancing effect led by CEP layer is not as significant as the rejection effect caused by PA layer since PA is rejecting ions by size, but CEP is preferably transporting cations but in different rates. which results in a lower permeation of Ca2+than Li+in general.

[0211] When CEP was placed to face the feed, Ca2+ions were transported dominantly and accumulated more amount than Li+after passing through the CEP layer. The concentration of ions remained unchanged through the PSf layer and PA layer was rejecting Ca2+to improve Li+transport. In this case, local Ca2+concentration is higher than Li+due to previous faster accumulation assisted by CEP layer. Previous data has proven that higher concentration before passing PA layer leads to higher permeation so that more Ca2+ion was measured at the extractantAttorney Docket No.: 072174-05101 chamber when comparing with PA-Feed set up. Monovalent / divalent selectivity accordingly decreased from 14.21 to 6.30.

[0212] The limited current density results are shown in FIG.8D supported the above by testing both sides of TFC-CEM using the voltage-current method. A clear plateau at around 2 V can be observed in the i-V figure when PA was facing the feed, and this plateau continued until 5 V before current density started to further increase. The Y-axis projection of this turning point between plateau and previous linearly increased current is defined as the limited current density, which caused by mass transfer limitation and happened across the interface when former phase transports ions slower than latter phase.

[0213] When CEP was firstly faced to the feed solution, the mass transfer limitation would happen between feed-CEP phase just like commercial CEMs. The limited current will occur when mass transfer of ions in aqueous feed phase is not rapid enough to compensate the transport difference between feed solution phase and solid CEP phase so that water will be dissociate then transport through the interface.

[0214] As comparison, when PA side faced to the feed solution, the limited current would occur not in feed-PA interface but between PA and CEP phase since ions are transport faster in bulk solution than through PA. Since water molecules can pass through the PA layer and saturated in the PSf layer, the diffusivity Ds, diffusion layer thickness δ, and transport number tf+can be estimated to be same as those in bulk solution. The limited current density is determined by ion concentration in former phase after excluding other fixed parameters. The ion concentration after PA layer is much lower than that in bulk solution in the same time since PA is rejecting but CEP is assisting ion transport so that the llim,PA-Feedis much lower than llim,CEP-Feed, which is consistent with limited current density study.Attorney Docket No.: 072174-05101 Ion Permeation Test In Synthetic Brine Scenario

[0215] Geothermal brine is an abundant but untapped lithium source that may enhance Li supply chain with efficient extraction process. Separating Li from divalent scaling cations is a major challenge for conventional evaporation process since scalants like CaSO4 and MgSO4 would impact Li2CO3purity and productivity by co-precipitation in subsequent precipitation. Using TFC- CEM by ED process can be used to solve this challenge by selectively transporting monovalent Li ions over divalent Ca2+and Mg2+.

[0216] To assess the performance of the TFC-CEM in ED process using geothermal brine as feed solution, a synthetic brine was prepared based on a modified geothermal brine recipe obtained from Department of Energy (DoE) with an original Ca / Li molar ratio of 25.0. Due to the unstable nature of geothermal brine, essential pretreatment has been done to ensure the stability of brine to be tested under lab condition. The pretreatment aimed at iron and silica elimination meanwhile preserving Li+ and Ca2+ ions. The Ca2+ / Li+ion molar ratio is 24.6 after pretreatment and detailed recipe can be found in TABLE IV. Due to much higher concentration of Na+existed in brine (2.5 mol L-1), current density was raised up to 2 mA / cm2and similar amount of Na+was added into permeate side to exclude excessive concentration diffusion, which may further impede Li+and Ca2+transport. TABLE IV Concentration Profile Of Major Cations In DOE Synthetic Brine Before And After Pretreatment Ion Li+Na+K+Ca2+Fe2+ / Fe3+Mn2+Attorney Docket No.: 072174-05101

[0217] During a 3 hours electrodialysis test, Li+concentration in permeated side was measured as 11.56 mmol L-1while Ca2+concentration reached to 2.60 mmol L-1. Correspondingly, the Ca2+ / Li+ion molar ratio of feed decreased 99.06% from 24.6 to 0.23 after crossing the membrane. FIG. 10A. the Li+ion flux was calculated as 117.35 mmol h-1m-2, which is much higher than 34.80 mmol h-1m-2of Ca2+flux.

[0218] Also, Li+ / Ca2+selectivity reached 84.96 that maintained a similar level with previous analysis when r=25 (88.26). Both Li+and Ca2+ion flux just sluggishly increased with 10 times higher current density since majority of current were contributed by high Na flux, which is the dominate species in this ED process. In this commercial ED process, 20~40 mA / cm2current density were applied for efficient desalination and resource recovery, thus a current-voltage curve for TFC-CEM was tested and is shown in FIG.10B. A maximum 37.65 mA / cm2of current density was observed when voltage across the cell raised up to 6 V, which is still possible to be further increased since the curve slope was still stable. The linear curve without appearance of plateau phase indicated our TFC-CEM are still under the ohm region at 37.65 mA / cm2of current density. This indicated that TFC-CEM can be applied under commercial current density without being restricted by the mass transfer limitation.

[0219] In addition, TFC-CEM showed enhanced Li+and Ca2+transport when higher current density was applied, so that different current density including 0.2, 1, 10, and 20 mA / cm2were performed on the ED cell with feed solution inside to monitor ion flux variation for Li+and Ca2+. FIG. 10C. A perfect linear relationship observation indicated that with higher current density applied, ion flux across the membrane could be enhanced by stronger driving force thus a faster ion transport can be achieved. Those preliminary results showed the great potential of TFC-CEMAttorney Docket No.: 072174-05101 to be applied in commercial ED process under industrial conditions for efficient Lithium extraction.

[0220] FIG. 11 depicts a process diagram of the integrated lithium selective electrodialysis system, in accordance with certain embodiments of the present invention.

[0221] The lithium selective electrodialysis system can allow for direct lithium extraction through the implementation of method that employs the removal of divalent ions through the use of a selective membrane, the transport of counter monovalent ions through the use of a tailored extractant, and the mitigation of impact of the harsh brine conditions through the use of membrane distillation coupled with a micro-template.

[0222] Electrodialysis, as one of the membrane desalination processes, uses an electrical field to separately remove positively and negatively charged species through ion exchange membranes, which selectively transport the counter-ions, such as for example cations as to cation exchange membranes, and reject the co-ions via Coulomb force.

[0223] In some embodiments, an electrodialysis process can operate at ambient temperature and pressure, which leads to a process and system more energy efficient than other desalination methods. Further, the membrane desalination electrodialysis process can achieve much higher water recovery, demand less chemical and energy consumption, have long membrane service life and is easy to operate. In fact, in some embodiments, over 85% of water recovery can be achieved by electrodialysis without extensive pretreatments, as it is more tolerant to silica, hardness, and organic matters, which normally lead to severe scaling and fouling issues in pressurized membrane processes.

[0224] As shown in the process diagram depicted in FIG. 11, the process may begin with the introduction of a brine. The brine may contain ions, such as for example but not limited to lithiumAttorney Docket No.: 072174-05101 ions (Li+), sodium ions (Na+), potassium ions (K+), calcium ions (Ca2+), chlorine ions (Cl-). The brine may also contain silica (SiO2), as shown through the stream composition of a geothermal brine entering the process in FIG.11.

[0225] In some embodiments, the lithium selective electrodialysis system and method may utilize a multi-effect membrane distillation process, as disclosed in the Floyd ’860 PCT Application, to pre-concentrate lithium using the thermal energy in the brine. Further, in such an embodiment, the use of a multi-effect membrane distillation process may also lower the temperature of the geothermal brine, which may allow for subsequent processes at the same time. In conjunction with the membrane distillation process, the lithium selective electrodialysis system and method may utilize a micro-template assisted microfiltration process to remove silica. In such a lithium selective electrodialysis system and method, the process may be scaled and the lifetime of the system may be expanded.

[0226] In some embodiments, the lithium selective electrodialysis system and method may involve the use of a selective membrane. The use of a selective membrane in the process may improve lithium ion (Li+) purity due to the removal of divalent ions. For example, the utilization of the selective membrane in the process may result in the removal of ions such as calcium (Ca2+), magnesium (Mg2+), thereof and other like combinations.

[0227] In some embodiments, the lithium selective electrodialysis system and method may utilize a monovalent-ion-selective hybrid membrane to enhance monovalent ion transport and remove high valent ions. The monovalent-ion-selective hybrid membrane may only allow monovalent cations such as Li+, Na+, and K+to transport through the membrane. As a result, in such an embodiment, the monovalent cations may become concentrated in the concentrate under electric field. Additionally, the specifically designed extractant solution introduces a reversedAttorney Docket No.: 072174-05101 concentration gradient of competing monovalent ions, such as for example but not limited to ions of sodium (Na+) and potassium (K+), to reduce their permeance. As a result, in such an embodiment, the lithium ion (Li+) selectivity may be increased.

[0228] Further, in some embodiments, the process may additionally involve the use of a tailored aqueous extractant solution to reduce the transport of monovalent ions that are not the selected target of the selective electrodialysis system and method. For example, in some embodiments, the process may result in the removal of ions such as sodium (Na+), potassium (K+), combinations thereof and other like combinations. The use of a selective membrane in the process may improve charge efficiency and decrease energy consumption.

[0229] The lithium selective electrodialysis process may use a lithium-selective membrane for the electrodialysis process, which can selectively and directly extract lithium ions (Li+) with reduced consumption of chemicals, water, and energy during the process. If the lithium selective membrane referred to in this paragraph is utilized, the stream will be largely free of any other cations, including monovalent cations such as sodium, potassium, etc.

[0230] Accordingly, in certain embodiments, the lithium selective electrodialysis system and method may produce a stream that is largely free of divalent cations. In such an embodiment, the stream may have a concentration with over ten times concentration of lithium compared to that which would be expected using prior extraction processes.

[0231] Following the creation of a concentrated lithium ion (Li+) rich brine, the process may continue with the production of a high-purity and valuable Li2CO3and LiOH·H2O through chemical precipitation of the lithium ions (Li+) in the brine.Attorney Docket No.: 072174-05101

[0232] In certain embodiments, the lithium selective electrodialysis system and method may be designed to achieve recovery of lithium at upwards of 95% of the original lithium contained in the brine.

[0233] Further, as shown in FIG. 11, the lithium selective electrodialysis process may be multi- stage, in order to provide a continuous process that allows for the removal of lithium depleted brine as well as the isolation and collection of a concentrated lithium ion (Li+) brine, which can then be processed to precipitate the lithium ions, as discussed above. In certain embodiments, and as shown in FIG.11, the lithium ion (Li+) precipitation may include the introduction of soda ash.

[0234] As shown in FIG. 11 and discussed in detail above, the lithium selective electrodialysis system and method may use a multi-effect membrane distillation process to pre-concentrate lithium using the thermal energy in the brine. During such a process in the lithium selective electrodialysis system and method, the geothermal brine post power generation can be first treated by the multi-effect membrane distillation process. In some embodiments, the temperature of the geothermal brine post power generation may be approximately 105oC.

[0235] Specifically, in such an embodiment, the multi-effect membrane distillation process may utilize the sensible heat in the geothermal brine as the thermal energy input. For example, the process may include feeding the sensible heat to the 1st effect, as shown in FIG. 11. Further, in some embodiments, the divalent cation-free, lithium-enriched concentrate from the 2nd stage electrodialysis may be utilized as the heat sink by feeding it to the higher effects, which concentrates both streams while generating pure water. Further, concurrently in some embodiments, the geothermal brine may be cooled to a desirable temperature safe for the electrodialysis process down-stream without any cooling equipment or additional energy consumption.Attorney Docket No.: 072174-05101

[0236] In some embodiments, the high temperature of the geothermal brine can lead to a heightened concentration of dissolved silica, which can slowly polymerize in the treatment system and foul surfaces of membranes, pipe wall, and other equipment when temperature decreases. To prevent silica fouling, the lithium selective electrodialysis system and method may include a micro-template (seed) assisted silica polymerization. In some embodiments, the micro-template (seed) assisted silica polymerization may involve a ceramic membrane filtration process to remove dissolved silica. In such an embodiment, a micro-template can be used to induce polymerization of silica on the micro-template surface. For example, the micro-template may be silica (SiO2) microspheres. In certain embodiments, the silica may polymerize on the micro-template surface instead of other surfaces, such as for example membranes, in the lithium selective electrodialysis system and method. The micro-template, in some embodiments, together with the precipitated silica may then be removed by a ceramic membrane. Achieving Li separation by LTO polymerized Thin Film Composite Membrane

[0237] A lithium titanium oxide (LTO) polymerized thin film composite membrane for selective Li+extraction in the presence of divalent cations (e.g., Ca2+) and other monovalent cations (e.g., Na+) has been discovered. In addition to act as a functional material, surface modified LTO also function as a building block during the interfacial polymerization process that forms the thin polyamide coating. A high Li+ / Na+selectivity of 13.58 was achieved using certain embodiments of the membrane, higher than other reported membranes of a similar scale. In addition, Li+ / Ca2+selectivity of 89.52 was also achieved. Membranes of embodiments of the present invention are capable of achieving higher selectivity with applied surface loading, and these show great potential in direct lithium extraction technology. Furthermore, the fabrication method addresses the generalAttorney Docket No.: 072174-05101 limitation of low selectivity suffered by most adsorbent coated / decorated membranes since it is suitable for a variety of inorganic adsorbents. Polymerization Ensures Uniform And High Loading Of LTO

[0238] The general synthesis route for n-LTO-PA layer is shown in FIGS.12A-12B. (LTO was synthesized using a hydrothermal method then modified with -NH2functional groups. LTO-NH2was then pre-polymerized with TMC and used to perform interfacial polymerization with MPD on the base membrane surface.)

[0239] The LTO nanoparticles can be first synthesized via a hydrothermal method and subsequently modified with -NH2 functional groups attached to the exposed oxygen sites in the LTO. The cation exchange base membrane (such as CEP-PSf membrane) can be fabricated as described above. Polymerization of LTO-NH2 with the cation exchange base membrane can then be performed. In a representative embodiment, polymerization of LTO-NH2with CEP-PSf base membrane can be performed as follows. The thin N-LTO-PA layer is synthesized on the small pore side of PSf base membrane via the optimized interfacial polymerization. For a more complete polymerization, LTO-NH2particles are pre-mixed with TMC then polymerized with MPD on the PSf side of the CEP-PSf base membrane surface to form a uniform selective layer. In detail, 10 mg of as-synthesized LTO-NH2particles are pre-mixed with 20 mL 0.4 wt% TMC in hexane phase and sonicate for 30 minutes. The PSf surface of the PSf-CEM base membrane is contacted with 20 mL of 2.0 wt% MPD aqueous solution for 3 min. Thereafter, the excess MPD solution is removed and the membrane is immersed in 2 mL of the TMC-LTO mixture for 30 seconds. This polymerization process is conducted for 2 times. Unreacted monomers are rinsed off using n- hexane, and the membrane is dried and cured at 60℃ for 10 min. As a comparison, pristine PAAttorney Docket No.: 072174-05101 membrane (i.e., no LTO) and LTO-PA membrane with unmodified LTO are also fabricated following the same method described above.

[0240] Surface morphologies and chemical structures of as-prepared bare LTO and LTO-NH2 nanoparticles were examined to confirm consistency with the designed structure. FIG.13A shows the Scanning Electron Microscopy (SEM) images of unmodified LTO crystals. No obvious morphological changes are observed between bare LTOs and LTO-NH2 (FIG. 13B). X-ray diffraction (XRD) analyses show excellent crystallity with standard Li2TiO3XRD pattern (FIG. 14A). The -NH2 modification of LTO is confirmed by Fourier-transform infrared spectroscopy (FT-IR) in FIG.14B, where N-H bend and N-H stretch peaks located in 1640 cm-1and 3400 cm-1are found in LTO-NH2.

[0241] The as-synthesized n-LTO-PA membrane was first characterized by SEM and TEM for membrane morphology and cross-sectional structures. SEM images show a large number of LTO nanoparticles uniformly distributed on the membrane surface. FIG. 13C. EDX mapping (FIG. 13D) shows uniform distribution of Ti and Si elements throughout the N-LTO-PA layer, further prove a high and uniform loading of LTO-NH2nanoparticles on surface. Notably, elemental mapping signals for N (dots) were also spotted in all test areas, indicating the complete polymerization of PA on base membrane surface. The XPS spectrum (FIGS.14C-14D) confirms the chemical composition of the n-LTO-PA layer with strong signal peaks of C, N, O, Ti and Si, which is consistent with EDX mapping results.

[0242] Low electrical resistance is favored in some embodiments since n-LTO-PA membrane is used as a cation exchange membrane (CEM) in the ED process. Electrochemical Impedance Spectroscopy (EIS) analysis (FIG. 14E) was conducted to determine membrane electrtical resistance. Using an equivalent circuit model, the n-LTO-PA membrane resistance is determinedAttorney Docket No.: 072174-05101 to be 5.48Ω df, slightly higher than the pristine PA membrane, which has a resistance of 4.26 Ω cm2. The increase of resistance is attributed to the addition of non-conducting LTO nanoparticles. However, the slight resistance is acceptable since 5.48 Ω cm2is still lower than the commercial requirement of a practical CEM, which is typically <15 Ω cm2.

[0243] The limiting current density is measured as an indicator of mass transfer limitation of membrane. FIG.14F. (For FIG.14F, the test condition was: 20 mM NaCl+20mM LiCl as feed and DI water for extractant; 0-10 V for sweeping range; tested membrane aera: 5 cm2). The limiting current density for the n-LTO-PA membrane is determined to be 0.50 mA / cm2.

[0244] Pristine PA coating, and LTO-PA coating using unmodified LTO were prepared as comparison.

[0245] Poor polymerization condition of LTO-PA membrane further showed that loading amount of LTO can be highly depending on the cross-linking degree of particles with surface, indicating a low Li selectivity due to few Li transport channel through whole membrane. A FT-IR analysis (FIG.14G) was also conducted to compare the bonding condition of pristine PA and N-LTO-PA. Typical peaks for PA layer were identified in both membranes located in 1011 cm-1, 1240 cm-1, 1486 cm-1, 1611 cm-1and 1664 cm-1as C-N, C-O, aromatic, -C=O stretch, and -CONH- bonds, respectively. However, N-LTO-PA membrane exhibited several new peaks, such as the Ti-O at 1905 cm-1and Si-O stretch at 830 cm-1, which further showed the successful loading of LTO into the PA layer. Interestingly, a more intensive C-N peak at 1011 cm-1and a very tiny C=O stretch was observed compared to pure PA and this variation proved the polymerization of LTO. More free -COCl groups on excessive TMC have been polymerized with -NH2 from LTO to form amide including C-N bond thus C-N peak increases while C=O stretch reduced.Attorney Docket No.: 072174-05101 n-LTO-PA Membrane Reverses Li+And Na+Transport

[0246] N-LTO-PA membrane was installed in a simplified ED cell and paired with a commercial AEM to measure electric potential driven ion transport performance. The same tests were performed using a commercial CEM, which was obtained from market, PA, and LTO-PA membrane prepared with unmodified LTO. FIG.15A. The mixed ion solution was filled into the feed chamber, DI water was filled in the extractant chamber and 20 mM KCl solution was filled in the electrolyte chamber. Ion concentrations in extractant chamber were measured timely to illustrate ion permeation kinetics.

[0247] Due to its smaller hydrated ion size and higher ion mobility, Na+dominates the overall cation transport when using the commercial CEM and the LTO-PA membrane, which is consistent with previous observations. FIGS. 16A-16B. (FIGS. 16A-16B shows lithium and sodium concentration variation in the extractant chamber using different membranes in binary (Li, Na) solution. For Li+, plots 1601-1604 are for n-LTO-PA, LTO-PA, PA, and CEM, respectively; and for Na+, plots 1611- 1614 are for N-LTO-PA, LTO-PA, PA, and CEM, respectively).

[0248] Preferred Na+transport is expected in CEM and even PA. The failure of achieving Li+selectivity by the LTO-PA membrane prepared with unmodified LTO was attributed to the low LTO loading resulting from poor compatibility of unmodified LTO with the PA matrix. However, the n-LTO-PA membrane exhibited high selectivity for Li+versus Na+transport.0.956 mmol of Li+was measured in the extractant chamber after 2 hours but only 0.308 mmol of Na+was found.

[0249] Realistic Li source brines are reported with very high concentration of divalent cations (i.e., Ca2+, and Mg2+) and other monovalent cations (i.e., Na+and K+) that interfere with Li+extraction. Accordingly, n-LTO-PA selectivity is evaluated in a tri-caion solution that contains Li+, Na+and Ca2+. FIG.16C. n-LTO-PA reached 3.11 as Li / Na selectivity and 85.52 as Li / Ca selectivity, which is 13.3 times and 203.6 times higher than that by CEM, respectively. Higher rejection against Ca2+Attorney Docket No.: 072174-05101 than Na+by PA layer was reported adequately due to larger ion size and consistent with our findings.

[0250] Membrane performance under different pH was evaluated since LTO selectivity is known to change with pH adjustment when used as an adsorbent. To investigate how LTO loading affects n-LTO-PA performance, membranes were fabricated with different LTO loadings from 0 mg (PA with excessive TMC), 3 mg, 10 mg (used in all tests) to 30 mg. Under same test conditions, the ion fluxes, selectivity, and surface morphology were shown in FIG.16D.0 mg membrane (which is also referred to as PA membrane), exhibited consistent result that Na+was mainly transported. Li+selectivity was observed when 3 mg of N-LTO was polymerized onto PA layer. Selectivity was further increased with more LTO added thus a Li+ / Na+selectivity of 13.58 was achieved when using 30 mg N-LTO-PA. With more LTO polymerized, more Li+transport channels were created so that Li+flux was observed rising with LTO amount. Stability

[0251] Stability of the n-LTO-PA membrane has been analyzed by testing Ti leakage in both feed and extractant chambers after experiment, and also by monitoring the morphological variation of membranes. After 20 h experiment, Ti concentration level was below ICP-OES detection limit (50 ppb) while Li+and Na+concentrations were accurately measured. SEM observation also confirmed the stability of synthesized membranes that all LTO contained membrane maintained similar morphology compared with pristine ones. Credited to high Ti-O bond energy, LTO showed excellent stability.

[0252] Accordingly, high Li+ / Na+selectivity in n-LTO-PA membrane can be achieved by a synergy of Li+selective channels provided LTO and high Na+resistant surfaces created by highly cross-linked PA. Such n-LTO-PA membrane has filled the technological gap in the current DLEAttorney Docket No.: 072174-05101 process for Li extraction with reportedly high Li+ / Na+selectivity among centimeter scale membranes. FIG. 17 shows (1) areas 1701-1703, respectively for previous reported lithium selective membranes, monovalent selective membranes, and non-selective membranes, and (2) area 1704 for the N-LTO-PA membrane herein. See also TABLE V. TABLE V Membrane Performance Comparison Number Functional layer Base membrane SLi / 1+SLi / 2+Reference 1 N-LTO-PA PSf+CEP 3.10 89.34 Herein

[0253] n-LTO-PA coating forms uniformly on PSf+CEP support, allowing it to function as a Li selective coating. When used in an ED process, n-LTO-PA membrane enabled high selectivity Li extraction with high current density. The easy synthesizing process, low modification requirement and high loading of inorganic adsorbent on base membrane can be used in broad applications in other water and wastewater resource recovery where the selective ion separation was needed but not achieved. The method can also be used to desalinate toxic ions or scalants while preserve other substances in solution.Attorney Docket No.: 072174-05101

[0254] FIG.18 shows a multi-pair ED cell for lithium extraction using TFC-CEM. The membrane pairs can be more than 5 pairs showed in FIG.18. FIG.19 shows a desalination ED cell for high quality water production containing divalent minerals and scale control in concentrate chamber using TFC-IEM. The membrane pairs can be more than 5 pairs showed in FIG.19.

[0255] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it should be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of specific embodiments are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the described embodiments to the precise forms disclosed. It should be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

[0256] While embodiments of the invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The embodiments described and the examples provided herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. The scope of protection is not limited by the description set out above, but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims.

[0257] Amounts and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numericalAttorney Docket No.: 072174-05101 range of approximately 1 to approximately 4.5 should be interpreted to include not only the explicitly recited limits of 1 to approximately 4.5, but also to include individual numerals such as 2, 3, 4, and sub-ranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges reciting only one numerical value, such as “less than approximately 4.5,” which should be interpreted to include all of the above-recited values and ranges. Further, such an interpretation should apply regardless of the breadth of the range or the characteristic being described. The symbol “~” is the same as “approximately”.

[0258] Various terms are used to refer to particular system components. Different companies may refer to a component by different names – this document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or a direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection or through an indirect connection via other devices and connections.

[0259] The terminology used herein is for the purpose of describing particular example embodiments only, and is not intended to be limiting. Following long-standing patent law convention, the terms “a” and “an” mean “one or more” when used in this application, including the claims.

[0260] As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performanceAttorney Docket No.: 072174-05101 in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0261] The terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers and / or sections; however, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer, or section from another region, layer, or section. Terms such as “first,” “second,” and other numerical terms, when used herein, do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the example embodiments. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. As used herein, the term “and / or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase “A, B, C, and / or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D. Accordingly, as an example, “at least one of: A, B, and C” includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C. In another example, the phrase “one or more” when used with a list of items means there may be one item or any suitable number of items exceeding one.

[0262] Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” “top,” “bottom,” and the like, may be used herein. These spatially relative terms can be used for ease of description to describe one element’s or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms may also beAttorney Docket No.: 072174-05101 intended to encompass different orientations of the device in use, or operation, in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein interpreted accordingly.

[0263] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0264] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter belongs. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are now described.

[0265] The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above invention is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.

[0266] Those skilled in the art will appreciate that although the previous paragraphs relate to embodiments where steps may be described as occurring in a certain order, no ordering is required unless otherwise stated. In fact, steps described in the previous paragraphs may occur in any order.Attorney Docket No.: 072174-05101 Furthermore, although one step may be described in one figure and another step may be described in another figure, embodiments of the present invention are not limited to such combinations, as any of the steps described above may be combined in particular embodiments.

[0267] Those skilled in the art will appreciate that the steps described herein may be carried out in a variety ways and that no particular ordering is required. It will be further understood from the foregoing description that modifications and changes may be made in various embodiments of the present invention without departing from its true spirit. The descriptions in this specification are for purposes of illustration only and are not to be construed in a limiting sense. REFERENCES

[0268] International PCT Patent Appl. No. PCT / US2021 / 041860, entitled “Spiral Wound Multi- Effect Membrane Distillation Module,” filed July 15, 2021, to John Allen Floyd, et al. (“Floyd ’860 PCT Application”)

[0269] United States Patent No. 9,849,450, entitled “Ion-Conducting Membranes,” issued to December 26, 2017, to Richard I. Masel, et al. (“Masel ’450 Patent”).

[0270] United States Patent No. 8,084,546, entitled “Method For Varying The Transport Properties Of A Film Cast From A Sulfonated Copolymer,” issued to December 27, 2011, to Carl Lesley Willis, et al. (“Willis ’546 Patent”).

[0271] Chen, Q.-B., et al., “Development of Recovering Lithium from Brines by Selective- Electrodialysis: Effect of Coexisting Cations on the Migration of Lithium,” Journal of Membrane Science, 2018, 548, 408–420 (“Chen 2018”).

[0272] Ji, Z., et al., “Preliminary Study on Recovering Lithium from High Mg2+ / Li+Ratio Brines by Electrodialysis,” Separation and Purification Technology, 2017, 172, 168–177 (“Ji 2017”).Attorney Docket No.: 072174-05101

[0273] Liu, G., et al., “Highly Selective Lithium Recovery from High Mg / Li Ratio Brines,” Desalination, 2020, 474, 114185 (“Liu 2020”).

[0274] Lu, J., et al., “Efficient Metal Ion Sieving in Rectifying Subnanochannels Enabled by Metal–Organic Frameworks,” Nat. Mater., 2020, 19 (7), 767–774 (“Lu 2020”).

[0275] Nie, X.-Y, et al., “Further Investigation into Lithium Recovery from Salt Lake Brines with Different Feed Characteristics by Electrodialysis,” Journal of Membrane Science, 2017, 530, 185– 191 (“Nie 2017”).

[0276] Pang, X., et al., “Preparation of Monovalent Cation Perm-Selective Membranes by Controlling Surface Hydration Energy Barrier,” Separation and Purification Technology, 2021, 270, 118768 (“Pang 2021”).

[0277] Paredes, C., et al, “Selective Lithium Extraction and Concentration from Diluted Alkaline Aqueous Media by a Polymer Inclusion Membrane and Application to Seawater,” Desalination, 2020, 487, 114500 (“Paredes 2020”).

[0278] Razmjou, A., et al., “Lithium Ion-Selective Membrane with 2D Subnanometer Channels,” Water Research, 2019, 159, 313–323 (“Razmjou 2019”).

[0279] Ren, C. E., et al., “Charge- and Size-Selective Ion Sieving Through Ti3C2Tx MXene Membranes,” J. Phys. Chem. Lett., 2015, 6 (20), 4026–4031 (“Ren 2015”).

[0280] Somrani, A., et al., “Study on Lithium Separation from Salt Lake Brines by Nanofiltration (NF) and Low Pressure Reverse Osmosis (LPRO),” Desalination, 2013, 317, 184–192 (“Somrani 2013”).

[0281] Warnock, S. J., et al., “Engineering Li / Na Selectivity in 12-Crown-4–Functionalized Polymer Membranes,” Proceedings of the National Academy of Sciences, 2021, 118 (37), e2022197118 (“Warnock 2021”).Attorney Docket No.: 072174-05101

[0282] Yu, H., et al., “Selective Lithium Extraction from Diluted Binary Solutions Using Metal- Organic Frameworks (MOF)-Based Membrane Capacitive Deionization (MCDI),” Desalination, 2023, 556, 116569 (“Yu 2023”).

[0283] Zhang, H., et al., “Ultrafast Selective Transport of Alkali Metal Ions in Metal Organic Frameworks with Subnanometer Pores,” Science Advances, 2018, 4 (2), eaaq0066 (“Zhang 2018”).

Claims

Attorney Docket No.: 072174-05101 CLAIMS WHAT IS CLAIMED IS:

1. A method for selectively recovering lithium from a brine source, the method comprising: (a) introducing a brine source, wherein the brine source comprises lithium ions; (b) introducing the brine source to an electrodialysis cell, wherein the electrodialysis cell comprises (i) a cathode, (ii) an anode, (iii) a feed brine channel, (iv) an extractant channel, (v) an anolyte channel, (vi) an anion-exchange membrane, and (vii) a selective cation exchange membrane having a thin film composite structure; (c) introducing a tailored aqueous extractant solution to a concentrate channel of the electrodialysis cell, wherein (i) the tailored aqueous extractant solution comprises a tailored concentration of competing monovalent cations, (ii) the brine source feed comprises a brine concentration of the competing monovalent cations, andAttorney Docket No.: 072174-05101 (iii) the tailored concentrations of competing monovalent cations are equal to or higher than the brine concentrations of the competing monovalent cations; and (d) resultant from introducing a tailored aqueous extractant solution, reducing transport of competing monovalent cations and enhancingtransport of target cation from the brine source, wherein the extractant solution becomes a lithium-concentrated brine.

2. The method of Claim 1, wherein the brine source is a geothermal brine.

3. The method of Claim 1 further comprising precipitating the lithium-concentrated brine.

4. The method of Claim 3 further comprising, resultant from precipitating the lithium- concentrated brine, producing a solid lithium product.

5. The method of Claim 3, wherein the lithium product comprises Li2CO3or LiOH·H2O.

6. The method of Claim 1, wherein the brine source comprises one or more of ions selected from the group consisting of sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chlorine (Cl-), and combinations thereof.

7. The method of Claim 1, wherein the brine source comprises silica (SiO2).

8. The method of Claim 1 further comprising, resultant to the distilling, pre-concentrating the lithium using thermal energy in the brine source.Attorney Docket No.: 072174-05101 9. The method of Claim 1, wherein the distillation and the micro-templating happen concurrently.

10. The method of Claim 1, wherein introducing the microtemplate comprises a ceramic membrane filtration process to remove dissolved silica.

11. The method of Claim 1 further comprising distilling at or below a particular temperature threshold.

12. The method of Claim 1 further comprising, resultant from distilling the brine source, introducing the brine source to a ceramic membrane.

13. The method of Claim 12, wherein the introducing the brine source to a ceramic membrane enhances the removalof silica (SiO2).

14. The method of Claim 1, wherein the aqueous extractant solution comprises concentrations of competing monovalent cations the same as or higher than the brine source feed.

15. The method of Claim 1 further comprising introducing a reversed concentration gradient of competing monovalent ions.Attorney Docket No.: 072174-05101 16. The method of Claim 15, wherein the competing monovalent ions comprise at leasst one of sodium (Na+) and potassium (K+).

17. The method of Claim 1, wherein the selective hybrid membrane comprises: (a) a cation exchange layer comprising a polymer having an ion exchange capacity of greater than 0.5 meq / g, the cation exchange membrane having a thickness of 1 to 200 µm; (b) a support layer having an average pore size ranging from 1 to 100 nm, wherein (i) the support layer has a thickness ranging from 10 to 200 µm, and (ii) the support layer has a first side and second side, the first side having a smaller pore size than the second layer; and (c) a polyamide layer having a thickness ranging from 5 to 200 nm, wherein (i) the polyamide layer is situated on the first side of the support layer, (ii) the cation exchange layer is situated on the second side of the support layer, (iii) the geothermal source comprises a mixture of two or more cations selected from the group consisting of Li, Na, Ca, Mg, K, Fe, Cu, and Zn, and (iv) the selective hybrid membrane is characterized as having at least one of a perm-selectivity of Li+ / Ca2+of greater than 5, and a perm-selectivity of Li+ / Mg2+of greater than 5.

18. The method of Claim 17, wherein the sulfonated polymer is selected from the group consisting of perfluorosulfonic acid polymers, sulfonated polyolefins, sulfonated polyimides, sulfonated polyamides, sulfonated polyesters, polystyrene sulfonates, sulfonated styrenic blockAttorney Docket No.: 072174-05101 copolymers, sulfonated polyolefins, sulfonated polysulfones, sulfonated polyketones, sulfonated polyphenylene ethers, and mixtures thereof.

19. The method of Claim 17, wherein the sulfonated polymer has a degree of sulfonation of 10 to 100 mol % and an ion exchange capacity of 0.5 to 2.6 meq / g.

20. The method of Claim 1, wherein the selective hybrid membrane comprises a first layer, a second layer, and a third layer.

21. The method of Claim 20, wherein the first layer of the selective hybrid membrane comprises a cation exchange polymer.

22. The method of Claim 20, wherein the second layer of the selective hybrid membrane comprises a porous polysufone membrane.

23. The method of Claim 20, wherein the third layer of the selective hybrid membrane comprises an ultra-thin polyamide coating.

24. A lithium selective electrodialysis system to selectively and directly extract lithium from brine source with high efficiency, the system comprising: (a) a brine source; and (b) an electrodialysis cell, the cell comprising (i) a cathode.Attorney Docket No.: 072174-05101 (ii) an anode, (iii) a feed brine channel, (iv) an extractant channel, (v) an anolyte channel, (vi) an anion-exchange membrane, and (vii) a selective cation exchange membrane having a thin film composite structure.

25. The system of Claim 24, wherein the brine source is a geothermal brine.

26. The system of Claim 24, wherein the brine source comprises one or more of ions selected from the group consisting of sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chlorine (Cl-), and combinations thereof.

27. The system of Claim 24, wherein the brine source comprises silica (SiO2).

28. The system of Claim 27, wherein the system further comprises an aqueous extractant solution, wherein the aqueous extractant solution comprises competing monovalent cation concentrations the same as or higher than the brine source feed.

29. The system of Claim 24, wherein the selective hybrid membrane comprises:Attorney Docket No.: 072174-05101 (a) a cation exchange layer comprising a sulfonated polymer having an ion exchange capacity of greater than 0.5 meq / g, the cation exchange membrane having a thickness of 1 to 200 µm; (b) a support layer having an average pore size ranging from 1 to 100 nm, wherein (i) the support layer has a thickness ranging from 10 to 200 µm, and (ii) the support layer has a first side and second side, the first side having a smaller pore size than the second layer; and (c) a polyamide layer having a thickness ranging from 5 to 200 nm, wherein (i) the polyamide layer is situated on the first side of the support layer, (ii) the cation exchange layer is situated on the second side of the support layer, (iii) the brine source comprises a mixture of two or more cations selected from the group consisting of Li, Na, Ca, Mg, K, Fe, Cu, and Zn, and (iv) the selective hybrid membrane is characterized as having at least one of a perm-selectivity of Li+ / Ca2+of greater than 5, and a perm-selectivity of Li+ / Mg2+of greater than 5.

30. The system of Claim 29, wherein the sulfonated polymer is selected from the group consisting of perfluorosulfonic acid polymers, sulfonated polyolefins, sulfonated polyimides, sulfonated polyamides, sulfonated polyesters, polystyrene sulfonates, sulfonated styrenic block copolymers, sulfonated polyolefins, sulfonated polysulfones, sulfonated polyketones, sulfonated polyphenylene ethers, and mixtures thereof.Attorney Docket No.: 072174-05101 31. The system of Claim 29, wherein the sulfonated polymer has a degree of sulfonation of 10 to 100 mol % and an ion exchange capacity of 0.5 to 2.6 meq / g.

32. A method of utilizing a fabricated monovalent selective ion exchange membrane for desalination, the method comprising: (a) forming a polyamide separation layer on the selective ion exchange membrane, wherein (i) the polyamide layer comprises one or more polyamides, (ii) each polyamide in the one or more polyamides has a polyamide chemistry, (iii) the forming of the polyamide separation layer on the selective ion exchange membrane results in a monovalent / divalent ion separation range, and (iv) the selective ion exchange membrane comprises a first layer comprising an ion exchange polymer, a second layer comprising a middle layer comprising a porous polysulfone membrane, and a third layer comprising the polyamide separation layer; (b) tuning the polyamide layer to optimize a perm-selectivity of targeted monovalent ions, wherein the target perm-selectivity is determined based on a composition of a brine source; (c) introducing the brine source to the monovalent selective ion exchange membrane, wherein the brine source comprises the targeted monovalent ions and one or more divalent ions; and (d) separating the one or more divalent ions from the targeted monovalent ions.Attorney Docket No.: 072174-05101 33. A monovalent selective ion exchange membrane comprising: (a) an ion exchange layer comprising a cation / anion exchange polymer; (b) a support layer, wherein (i) the support layer comprises a first side having a first pore size, (ii) the support layer comprises a second side having a second pore size, and (iii) the second pore size is larger than the first pore size; (c) a polyamide layer, wherein (i) the polyamide layer is situated on the first side of the support layer, (ii) the ion exchange layer is situated on the second side of the support layer, and (iii) the monovalent selective ion exchange membrane has a perm-selectivity, wherein the perm-selectivity is at least one of a monovalent / divalent perm- selectivity that is greater than 5.

34. The monovalent selective ion exchange membrane of Claim 33, wherein the cation / anion exchange polymer has an ion exchange capacity of greater than approximately 0.5 meq / g.

35. The monovalent selective ion exchange membrane of Claim 33, wherein the ion exchange layer has an ion exchange membrane thickness in a range between approximately 1 µm and approximately 50 µm.

36. The monovalent selective ion exchange membrane of Claim 33, wherein the support layer has an average pore size in a range between approximately 0 nm and approximately 100 nm.Attorney Docket No.: 072174-05101 37. The monovalent selective ion exchange membrane of Claim 33, wherein the support layer has a support layer thickness in a range between approximately 10 µm and approximately 200 µm.

38. The monovalent selective ion exchange membrane of Claim 33, wherein the polyamide layer has a polyamide layer thickness in a range between approximately 5 nm and approximately 200 nm.Attorney Docket No.: 072174-05101 39. A lithium titanium oxide (LTO) polymerized thin film composite membrane for Li+selection over Na+and Ca2+, wherein the membrane has a Li+ / Ca+selectivity that is greater than 5 and the membrane has a Li+ / Na+selectivity that is greater than 5.

40. The LTO polymerized thin film composite membrane of Claim 39, wherein the Li+ / Ca+selectivity is greater than 50 and the Li+ / Na+selectivity that is greater than 10.

41. The LTO polymerized thin film composite membrane of Claim 39, wherein the LTO polymerized thin film composite membrane is an N-LTO-PA membrane.

42. A method of making a lithium titanium oxide (LTO) polymerized thin film composite membrane, wherein the method comprises: (a) selecting LTO particles; (b) modifying the LTO particles with -NH2functional groups attached to exposed oxygen sites in the LTO, (c) polymerizing the modified LTO particles with a cation exchange base membrane to form the LTO polymerized thin film composite membrane, wherein theAttorney Docket No.: 072174-05101 membrane has a Li+ / Ca+selectivity that is greater than 5 and the membrane has a Li+ / Na+selectivity that is greater than 5.

43. The method of Claim 42, wherein the LTO particles are LTO nanoparticles.

44. The method of Claim 42, wherein (a) the LTO particles are pre-mixed with trimesoyl chloride (TMC) before the step of polymerization; and (b) during the step of polymerization, the cation exchange base membrane has m- phenylenediamine (MPD) on a surface.

45. The method of Claim 42, wherein the LTO polymerized thin film composite membrane is an N-LTO-PA membrane.

46. A method comprising: (a) selecting a lithium titanium oxide (LTO) polymerized thin film composite membrane having a Li+ / Ca+selectivity that is greater than 5 and the membrane has a Li+ / Na+selectivity that is greater than 5; (b) utilizing the LTO polymerized thin film composite membrane as the selective cation exchange membrane to selectively recover lithium in a process selected from the group consisting of the methods of Claims 1-23.Attorney Docket No.: 072174-05101 47. A system comprising a system selected from the group consisting of the system of Claims 24-31, wherein the selective cation exchange membrane in the system is a lithium titanium oxide (LTO) polymerized thin film composite membrane having a Li+ / Ca+selectivity that is greater than 5 and the membrane has a Li+ / Na+selectivity that is greater than 5.

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