Method for recovering lithium from brines by using terpyridine-functionalised composites

Abstract

The present invention relates to a method for recovering lithium from natural or artificial brines that comprises preparing a terpyridine-functionalised composite, contacting the brine with the functionalised composite inside a filtering bag in a column, maintaining contact until a functionalised composite-lithium complex is formed, controlling the process until the saturation of the functionalised composite-lithium complex is reached, acidifying the complex with a strong acid to release the lithium and recovering the lithium. The composite formed with mesoporous materials on a nano- or micrometre scale is capable of extracting and concentrating the lithium after initial contact with said composite for at least 48 hours at room temperature. The formed composites exhibit a high lithium-bonding capacity based on brines with lithium concentrations as low as 2 ppm, in addition to being very strong. This lithium can be easily released by means of a change in pH, with a strong acid.

Description

[0001] METHOD FOR RECOVERING LITHIUM FROM BRINES BY USING COMPOSITES FUNCTIONALIZED WITH TERPYRIDINES.

[0002] Scope:

[0003] The invention relates to the recovery of lithium from brines of natural or artificial origin, which contain it, by contacting the brine with terpyridines alone or with terpyridines forming a selective part of composites formed with mesoporous materials.

[0004] Lithium has various uses, primarily as an energy source, for example, in energy storage in battery manufacturing and solar thermal technology. Lithium's high electrochemical potential and higher energy density compared to other metals allow batteries to charge quickly, have high durability, and a higher voltage, giving them a longer lifespan.

[0005] Furthermore, lithium has been used for decades in various industrial activities, such as the manufacture of ceramics, glass, synthetic rubber, and lubricants; in the aluminum industry; and in the development of medications for the treatment of medical disorders such as anxiety, depression, and bipolar disorder.

[0006] Summary:

[0007] The invention describes a method that uses terpyridines alone or as part of a granulated composite with mesoporous materials at the nanometric and micrometric scale, for the extraction of lithium, through the contact of lithium brines of natural or artificial origin with said terpyridines.

[0008] Terpyridines alone or forming a composite with mesoporous materials at a nanometric or micrometric scale, when in contact with brines or solutions containing lithium, are capable of extracting and concentrating lithium after an initial contact of at least 48 hours, at room temperature with said composite, where the terpyridines are recovered through an acidification process with strong acid such as hydrochloric acid or sulfuric acid, to change the pH and recover the lithium.

[0009] Terpyridines, alone or in composites, exhibit high lithium binding capacity from brines with lithium concentrations as low as 2 parts per million, and are also very resistant, where this lithium can subsequently be easily released by a change in pH, thanks to the action of a strong acid.

[0010] State of the art:

[0011] Lithium can be extracted from deposits such as brines, pegmatites or hard rocks, sedimentary rocks, enriched clays, and seawater. Each of these deposits has a distinct processing method, and the processing will depend on the lithium concentration and whether the lithium is present alone or in combination with other elements. This processing will depend on the type of final product desired. However, regardless of the type of processing used, all involve the presence of lithium brine, which must be subsequently processed using non-selective and selective lithium recovery methods.

[0012] Most of Chile's lithium reserves come from continental geothermal brines. Lithium is extracted primarily from hard rock brines and brine deposits, where the traditional method is through evaporation ponds. The brine is left in large evaporation ponds for an extended period (24 to 36 months), waiting for the sun to evaporate the water contained in the brines. This method is costly, environmentally harmful, and slow, which does not guarantee future demand in the lithium markets.

[0013] There is currently a diverse literature that discusses the recovery or purification of lithium from various sources, such as lithium solutions, disused batteries, seawater, brines, salt lakes, etc. Most of them use inorganic chemistry reactions, with pH changes to precipitate lithium salts or contaminants, followed by subsequent filtration, nanofiltration, crystallization, electrochemical methods, precipitation, heat treatments, electrodialysis, ion exchange and / or vaporization.

[0014] Document JPH0326334 (A), published on 04.02.1991, in the name of Agency of Industrie Science & Technology, relates to a lithium recovery agent and its production. This document relates to the selective separation of lithium from a solution containing many kinds of metal ions at a high efficiency by replacing hydrogen with L¡ or Mg contained in a multiple oxide comprising a metallic element L¡ or Mg and polyvalent metallic elements such as Mn and Ti. The multiple oxide comprising the metallic element L¡ or Mg and polyvalent metallic elements such as Ti, Sb, Mg, etc., is transported by a heat-resistant porous material and treated with acid to elute the L¡ or Mg from the multiple oxide. This multiple oxide is then used as a L¡ recovery agent for separating L¡ from seawater, hot groundwater, etc.By having the porous material carry the ionic sieve-type sorbent for Li, the latter can be selectively and efficiently isolated and recovered from a solution containing various types of metal ions.

[0015] JPH026844 (A), published on January 11, 1990, in the name of the Agency of Industry Science & Technology, relates to a synthetic lithium adsorbent that selectively adsorbs lithium from solutions containing various metal ions and a method for producing the same. The adsorbent comprises a lithium-antimony compound oxide, which is treated with acid, wherein the adsorbent has the general formula Lii-xHxSbOs (wherein the value of x in the formula is 0 < x < 1 ). The synthetic lithium adsorbent of the said document is obtained by treating a lithium-antimony compound oxide having an ideal composition of LiSbO with an acid to elute lithium. The lithium-antimony compound oxide as a raw material can be produced by heat-treating a mixed powder of a lithium compound and antimony oxide at a predetermined temperature of 500°C to 1000°C. Examples of lithium compounds used include carbonates, nitrates, chloride oxides and the like.Commercially available powders can be used as is. In addition, as antimony oxide, for example, commercially available powdered antimony oxides having a valence of 3, 4, or 5 can be used. Any of the above lithium and antimony oxide compounds is thoroughly ground and mixed so that the atomic ratio of lithium and antimony is 1:1, and the mixture is heat treated at a predetermined temperature in the range of 500°C to 1000°C. By this method, a lithium-antimony composite oxide having a composition of LiSbOs is obtained. Ideally, the Li / Sb ratio is 1, but values ​​between 0.5 and 1.5 are acceptable. The synthetic lithium adsorbent can be obtained by washing the composite oxide with an acid solution and eluting the lithium in the composite oxide.The acid solution used to elute lithium may be any acid solution, but preferably a mineral acid solution such as hydrochloric acid, sulfuric acid, or nitric acid having a pH of 1 or less. When the synthetic lithium adsorbent is used in a solution, it has a high lithium adsorption capacity, high lithium selectivity, and exhibits excellent lithium adsorption properties. With respect to lithium selectivity, when only the starting material, antimony oxide, was treated under the above production conditions, it did not exhibit any adsorption capacity. This adsorbent can be suitably used to selectively recover LI from solutions having low lithium concentrations, such as seawater, geothermal hot water, and hot spring water containing other metal ions.

[0016] Document US11365128 (B2), published on June 21, 2022, in the name of Energysource Minerals LLC, deals with a process for the selective adsorption and recovery of lithium from synthetic and natural brines, and more particularly with a process for recovering lithium from synthetic or natural brine solutions, by passing the brine solution through a lithium-selective adsorbent and a continuous countercurrent adsorption and desorption circuit. The adsorbent used in said document corresponds to alumina.

[0017] Document JP2020193130 A, published on 03.12.2020, in the name of Sumitomo Metal Mining Co., deals with a method for producing lithium hydroxide capable of obtaining lithium hydroxide at low cost.The method comprises the following steps: (1) a lithium adsorption step, wherein a first lithium-containing solution is brought into contact with a lithium-selective adsorbent to adsorb lithium to the lithium-selective adsorbent; (2) a lithium elution step, wherein lithium is eluted from the lithium-selective adsorbent on which lithium is adsorbed to obtain a second lithium-containing solution; (3) an impurity removal step, wherein a portion of metal ions is removed from the second lithium-containing solution to obtain a third lithium-containing solution, and (4) an electrodialysis step, wherein a lithium salt contained in the third lithium-containing solution is converted into lithium hydroxide to obtain a lithium hydroxide-containing solution in which lithium hydroxide is dissolved. The adsorbent used is alumina.

[0018] Document CN114196840 A, published on March 18, 2022, in the name of Jiangsu Jiuji High Tech Share Ltd. Company, deals with a method for extracting lithium from high-sodium brine using a columnar aluminum adsorbent. According to the method, lithium is extracted from the high-sodium lithium-containing solution with high yield, the sodium-lithium ratio in the desorption solution is reduced, operational feasibility for further purification and concentration of the desorption solution is provided, and energy consumption is reduced.

[0019] Document JPH038443, published on 16.01.1991, in the name of the Agency of Industry Science & Technology, deals with the production of easily handled lithium, capable of separating and recovering lithium from a dilute lithium solution, and allowing repeated adsorption and desorption, by covering the powder capable of adsorbing lithium with a porous membrane. Wherein the adsorbent is based on manganese oxide, which is covered with a porous membrane such as a membrane filter, an ultrafiltration membrane or a dialytic membrane. The lithium is adsorbed on the adsorbent and desorbed with an acid solution.

[0020] The paper CN115181865 A, published on 14.10.2022 by Shanxi University, belongs to the technical field of lithium extraction from salt lake brine, and particularly relates to a pH-responsive lithium extraction membrane and a preparation and application method thereof. The lithium extraction membrane comprises polyvinylidene fluoride and phenol crown ether lithium extraction molecules loaded onto polyvinylidene fluoride, and the mass ratio of polyvinylidene fluoride to phenol crown ether lithium extraction molecules is 100-150.

[0021] JP2022114567 A, published on August 8, 2022, on behalf of Nitto Denko Corp., proposes using a lithium ion permeable membrane for lithium purification. It comprises a polymer base material (cellulose acetate, cellulose acetate, polyvinyl chloride, and polyvinylidene fluoride) and a lithium extractant (phosphorus compounds having a P=0 bond and [3-diketones]) that is retained by the polymer base material and selectively captures or releases lithium ions.

[0022] Document CL202002938, published on 02 / 26 / 2021, on behalf of Energysource Minerals LLC, describes a process for selective absorption and recovery of lithium from natural and synthetic brines, and more particularly, to a process for recovery of lithium from a natural or synthetic brine solution by passing the brine solution through a lithium selective adsorbent in a continuous countercurrent adsorption and desorption circuit, wherein the selective adsorbent is a lithium alumina intercalator.

[0023] Document CL202101426, published on 26.11.2021, in the name of Sumitomo Metal Mining Co. Ltd., describes a process for producing a lithium-containing solution, which is carried out by adsorption in which a lithium adsorbent obtained from lithium manganese oxide is contacted with a lithium-containing liquid, obtaining post-adsorption lithium manganese oxide; the elution in which said oxide is contacted with an acid solution to obtain a lithium-containing solution with residual manganese; and the oxidation of manganese to obtain a lithium-containing solution.

[0024] Document CL201503393, published on 03.02.2017, in the name of Tibet Jin Hao Investment Co., Ltd. and Zhu Binyuan, describes a method and system for rapidly extracting lithium carbonate from saline lake water, comprising the following steps: introducing the lithium-rich brine into a reduced-pressure evaporation crystallizer to allow lithium carbonate to reach supersaturation and precipitate from the lithium-rich brine by evaporation under reduced pressure; discharging the residual liquid, collecting the precipitate in the crystallizer and drying the precipitate to obtain lithium carbonate crystals. Document CL202100019, published on 24.05.2021 , on behalf of Moselle Technologies, LLC, describes a method for recovering lithium ions from a lithium ion-containing liquid, the method comprising the steps of coating a nanoparticle with a styrene monomer; polymerizing the styrene monomer to form a polystyrene-coated nanoparticle; coupling a dibenzo-12-crown-4 ether to the polystyrene-coated nanoparticle to form a lithium adsorbent medium; exposing the lithium ion-containing liquid to the lithium adsorbent medium to form a lithium-rich adsorbent medium; and extracting the lithium ion from the lithium-rich adsorbent medium.

[0025] WO2020131964 A1, published on June 25, 2020, in the name of 6th Wave Innovations Corp., provides Molecular Recognition Technology (MRT) for selectively sequestering lithium from brines, leachates, or other natural or synthetic chemical mixtures. The disclosure also provides MRT extractants, ligands, beads, and methods for producing and utilizing them.

[0026] While many methods for extracting lithium from its various sources are known, procedures that reduce recovery times and are environmentally friendly are still being sought.

[0027] The technology proposed in the present invention allows lithium extraction in approximately two weeks at half the cost of the aforementioned procedures, uses 20 to 80% less water and physical space, and therefore has a lower environmental impact. This technology for lithium extraction is easily scalable, regardless of whether the source is a lithium-containing solution, originating from a salt flat, rock processing, seawater, or even artificial brines. Description of the figures:

[0028] Figure 1: Absorbance spectrum for 4'-phenyl-2,2':6',2"-terpyridine (TP2- 0).

[0029] Figure 2: Absorbance spectrum for 4'-(4-cyanophenyl)-2,2':6',2"-terpihdine (TP2-CN).

[0030] Figure 3: Absorbance spectrum for 4'-(4-carboxyphenyl)-2,2':6',2"- terpihdine (TP2-COOH).

[0031] Figure 4: Absorbance spectrum for 4'-phenyl-3,2':6',3"-terpyridine (TP3- 0).

[0032] Figure 5: Absorbance spectrum for 4'-(4-cyanophenyl)-3,2':6',3"-terpihdine (TP3-CN).

[0033] Figure 6: Absorbance spectrum for 4'-(4-carboxyphenyl)-3,2':6',3"- terpihdine (TP3-COOH).

[0034] Figure 7: Absorbance spectra for 4'-(4-R-phenyl)-2,2':6',2"-terpindine (TP2-0 with R=H, TP2-CN with R=CN,TP2-COOH with R=COOH). and for 4'-(4-R-phenyl)-3,2':6',3"-terpindine (TP3-0 with R=H, TP3-CN with R=CN,TP3- COOH with R=COOH.

[0035] Figure 8: Excitation (red line) and emission (black line) spectra for 4'-phenyl-2,2':6',2"-terpyridine (TP2).

[0036] Figure 9: Excitation (red line) and emission (black line) spectra for 4'-(4-cyanophenyl)-2,2':6',2"-terpyridine (TP2CN).

[0037] Figure 10: Excitation (red line) and emission (black line) spectra for 4'-(4-carboxyphenyl)-2,2':6',2"-terpyridine (TP2COOH).

[0038] Figure 11: Excitation (red line) and emission (black line) spectra for 4'-phenyl-3,2':6',3"-terpyridine (TP3). Figure 12: Excitation (red line) and emission (black line) spectra for 4'-(4-cyanophenyl)-3,2':6',3"-terpyridine (TP3CN).

[0039] Figure 13: Excitation (red line) and emission (black line) spectra for 4'-(4-carboxyphenyl)-3,2':6',3"-terpyridine (TP3C00H).

[0040] Figure 14: Titration for 4'-phenyl-2,2':6',2"-terpyridine (TP2) with L¡ + , to determine the amount of lithium captured by TP2.

[0041] Figure 15: Fluorescence graph of 4'-phenyl-2,2':6',2"-terpyridine (TP2) versus L¡ concentration. + at 276 nm.

[0042] Figure 16: Titration for 4'-(4-cyanophenyl)-2,2':6',2"-terp¡hdine (TP2CN) with L¡ +, to determine the amount of lithium captured by TP2CN.

[0043] Figure 17: Fluorescence graph of 4'-(4-cyanophenyl)-2,2':6',2"-terp¡hd¡ne (TP2CN) versus L¡ concentration. + at 276 nm.

[0044] Figure 18. Photograph showing the changes in the color of the mesoporous material when it is functionalized and then when the composite reacts with Lithium.

[0045] Figure 19: Infrared spectrum graph of non-functionalized aluminosilicate.

[0046] Figure 20: Infrared spectrum graph of aluminosilicate functionalized with terpihdine.

[0047] Figure 21: IR spectra of the composite alone (black) and the composite bonded to Lithium (red).

[0048] Figure 22: Excitation (a) and emission (b) spectra for the composite alone and the lithium-bonded composite.

[0049] Figure 23: Possible terpyridine species at different pH. Figure 24: Graph of the distribution of terpyridine microspecies with respect to pH.

[0050] Figure 25: Graph of the composition of each element present in the sample of the composite of the invention.

[0051] Figure 26: Diffractogram of the crystal profile for the chosen mesoporous material sample.

[0052] Figure 27a: SEM image of agglomerated particles of the nanometric-sized composite.

[0053] Figure 27b: SEM image of agglomerated particles of the micron-sized composite.

[0054] Figure 28: Semi-quantitative EDS analysis for the Li-composite.

[0055] Figure 29: Calibration curve for CT, obtained through EDS (energy dispersive spectroscopy).

[0056] Figure 30: Simulation of the affinity of the terpyridine molecule for lithium.

[0057] Figure 31: Column diagram where lithium absorption is carried out with the composite of the invention.

[0058] Figure 32: Flowchart diagram of the invention process.

[0059] Detailed description of the invention:

[0060] The lithium recovery and purification technology of the present invention is based on the selective chemical affinity for lithium of terpyridines alone or as part of a composite at a nanometric or micrometric scale, which has been developed in the present invention.

[0061] The properties of terpyridines, alone or as part of nanometric or micrometric composites, allow them to trap lithium, separating it from the other molecules present, and then release the lithium from the composite through a change in pH, leading to efficient and rapid lithium recovery, which is also low cost.

[0062] Due to the properties of terpyridines alone or as part of nano or micrometric scale composites, they are not able to specifically bind to other elements that interfere with the purification of lithium and that are always present together with it and represent one of the biggest problems in the industry, these elements are mainly calcium and magnesium, of the alkaline earth metals of the periodic table of elements.

[0063] The terpyridines, alone or as part of nanomethod or micromethod scale composites of the invention, are capable of binding to lithium selectively and with high affinity, which allows lithium to be recovered from brines with concentrations of parts per million of lithium, thereby expanding the potential extraction sites that have been neglected over time due to their low lithium content.

[0064] The terpyridines, alone or as part of nanometric or micrometric scale composites, of the invention are related to terpyridine derivatives, multidentate ligands with heterocyclic rings that have N-donor atoms.

[0065] According to the studies carried out in the present invention, substituted terpihdine derivatives are of particular interest, such as, for example, 4'-phenyl-2,2':6',2"-terpihdine, 4'-(4-hydroxyphenyl)-2,2':6',2"-terpihdine, 4'-(4-cyanophenyl)-2,2':6',2"-terpihdine and 4'-(4-carboxyphenyl)-2,2':6',2"-terpihdine, as shown below:

[0066]

[0067] Due to their strong chelating tendency, these ligands can form stable complexes with several different head groups and transition metal ions, even with lanthanide ions.

[0068] Terpyridine-metal systems have been studied to date for a wide variety of potential applications, such as nanotechnology, molecular storage, catalysis, biological activity, and so on. Many studies have focused on the use of terpyridine-metal complexes as potential luminescent devices and chemical detectors. The metals studied are group 8-10 transition metals, such as cobalt, nickel, zinc, and ruthenium.

[0069] However, studies of terpihdines with group I metals (such as lithium, sodium and potassium) are scarce and have been limited to the theoretical field and study of the solubility of salts in ionic liquids.

[0070] Thus, the synthesis of composites formed by substituted derivatives of terpyridine or of terpyridines alone at the nanometric or micrometric scale is the first step towards achieving selective, efficient and low-cost lithium recovery.

[0071] Characterization of terpihdines for selective lithium uptake

[0072] 1.-) The terpyridines used in this invention were characterized by spectrometry in the UV-visible range, to determine the absorbance maxima, also representing the fingerprint of the terpyridine compounds, allowing quality control of the reaction and its results.

[0073] Figures 1 to 7 show the graphs of absorbance versus wavelength for each of the terpihdines studied:

[0074] • 4'-phenyl-2,2':6',2”-terpyridine (figure 1).

[0075] • 4'-(4-cyanophenyl)-2,2':6',2"-terpinene (figure 2).

[0076] • 4'-(4-carboxyphenyl)-2,2':6',2"-terp¡hd¡ne (figure 3).

[0077] • 4'-phenyl-3,2':6',3"-terpyridine (figure 4).

[0078] • 4'-(4-cyanophenyl)-3,2':6',3"-terpinene (figure 5).

[0079] • 4'-(4-carboxyphenyl)-3,2':6',3"-terp¡hd¡ne (figure 6).

[0080] • Comparison between the different terpihdines: 4'-(4-R-phenyl)-2,2':6',2"- terpihdine and 4'-(4-R-phenyl)-3,2':6',3"-terpihdine, where R= H, CN, COOH (figure 7).

[0081] In the graph in Figure 1, absorbance is related to wavelength in the range of 240 to 500 nm, where the maximum absorbance (0.30 absorbance unit, au) for 4'-phenyl-2,2':6',2"-terpyridine (TP2-0) is located at 276 nm. This implies that the energy corresponding to this region of the electromagnetic spectrum causes electronic transitions at wavelengths characteristic of the molecular structure of this compound.

[0082] The graph in Figure 2 relates the absorbance with the wavelength in the range of 240 to 500 nm, where the maximum absorbance (0.22 au) for 4'-(4-cyanophenyl)-2,2':6',2"-terp¡hd¡ne (TP2-CN) is located at 276 nm with a small shoulder at 330 nm. This implies that the energy corresponding to this region of the electromagnetic spectrum causes electronic transitions at wavelengths characteristic of the molecular structure for this compound. The graph in Figure 3 relates the absorbance with the wavelength in the range of 240 to 500 nm, where the maximum absorbance (0.24 au) for 4'-(4-carboxyphenyl)-2,2':6',2"-terp¡hd¡ne (TP2-COOH) is located at 274 nm. This implies that the energy corresponding to this region of the electromagnetic spectrum causes electronic transitions at wavelengths characteristic of the molecular structure for this compound.

[0083] The graph in Figure 4 relates the absorbance with the wavelength in the range of 240 to 500 nm, where the maximum absorbance (0.15 ua) for 4'-phenyl-3,2':6',3"-terpyridine (TP3-0) is located at 254 nm with a small shoulder at 318 nm. This implies that the energy corresponding to this region of the electromagnetic spectrum causes electronic transitions at wavelengths characteristic of the molecular structure for this compound.

[0084] The graph in Figure 5 relates the absorbance with the wavelength in the range of 240 to 500 nm, where the maximum absorbance (0.20 ua) for 4'-(4-cyanophenyl)-3,2':6',3"-terp¡hd¡ne (TP3-CN) is located at 258 nm with a small shoulder at 324 nm. This implies that the energy corresponding to this region of the electromagnetic spectrum causes electronic transitions at wavelengths characteristic of the molecular structure for this compound.

[0085] The graph in Figure 6 relates the absorbance with the wavelength in the range of 240 to 500 nm, where the maximum absorbance (0.33 ua) for 4'-(4-carboxyphenyl)-3,2':6',3"-terp¡hd¡ne (TP3-COOH) is located at 273 nm. This implies that the energy corresponding to this region of the electromagnetic spectrum causes electronic transitions at wavelengths characteristic of the molecular structure for this compound.

[0086] The graph in Figure 7 relates absorbance to wavelength in the range of 240 to 500 nm, and compares the spectra of the six terpihdines used as examples. This demonstrates the differences between each one, which represents their fingerprint. It can be seen that the absorbance maxima vary between 0.15 and 0.33 AU for the terpihdines studied.

[0087] 2.-) In addition, the terpihdines used in this invention were characterized by their fluorescence spectra, based on the absorbance results, where the fluorescence emission maxima are determined. This maximizes the process sensitivity and its external traceability.

[0088] Figures 8 to 13 show the excitation spectra graphs (ex, red line) and emission (em, black line) for each of the terpihdines used:

[0089] • 4'-phenyl-2,2':6',2"-terpihdine (figure 8).

[0090] • 4'-(4-cyanophenyl)-2,2':6',2"-terpinene (figure 9).

[0091] • 4'-(4-carboxyphenyl)-2,2':6',2"-terp¡hd¡ne (figure 10).

[0092] • 4'-phenyl-3, 2':6',3"-terpihd ¡na (figure 11).

[0093] • 4'-(4-cyanophenyl)-3,2':6',3"-terpinene (figure 12).

[0094] • 4'-(4-carboxyphenyl)-3,2':6',3"-terp¡hd¡ne (figure 13).

[0095] Excitation spectra (red lines in Figures 8 to 13) record the emission intensity at a given frequency as a function of the excitation light wavelength. Excitation is performed with light of varying wavelength and fixed intensity.

[0096] To determine the emission spectrum (black lines in Figures 8 to 13), the maximum absorption wavelength determined for that compound (absorption spectrum in Figures 1 to 6) is used to excite it at that wavelength and thus determine the emission maximum. An emission spectrum is a record of the emission intensity as a function of the wavelength of the emitted light. In the emission spectrum, the excited molecule loses excess energy radiatively, which in this case it does through fluorescence.

[0097] The fluorescence intensity values ​​obtained for the terpyridines studied vary between 0.9 and 1.55 for the excitation spectra and between 0.8 and 1.65 for the emission spectra in figures 8 to 13.

[0098] Use of terpyridines to selectively bind lithium in solution

[0099] Based on the above results, fluorescence spectra were obtained for the 4-phenylterpyridines studied in the presence of lithium. A notable decrease in fluorescence is observed as the lithium concentration increases, indicating the binding of Li at concentrations as low as parts per million (Figures 14 to 17).

[0100] Figures 14 and 16 refer to the following terpyridines:

[0101] • 4'-phenyl-2,2':6',2"-terpyridine (TP2) with L¡ + (figure 14).

[0102] • 4'-(4-cyanophenyl)-2,2':6',2"-terp¡hdine (TP2CN) with L¡ + (figure 16).

[0103] Figure 14 shows a spectrum that records the intensity of the emission as a function of the wavelength of the emitted light, where the different curves correspond to different amounts of lithium added to the TP2-functionalized composite.

[0104] The black line in the spectrum corresponds to the composite with TP2 without the addition of L¡ + , the first addition of 5 pL of a 0.5 mM solution of L¡ + , is represented by the red line. Subsequently, volumes of the L¡ solution were successively added. +, up to 50 pL (represented by the pink line). As the lithium concentration increases, the fluorescence of 4'-phenyl-2,2':6',2"-terpyridine (TP2) decreases, which is attributed to the union of both compounds (terpyridine and lithium), generating changes in the structure of terpyridine, which is reflected in the gradual decrease in fluorescence with the addition of lithium.

[0105] In Figure 16, similar to Figure 14, but with the terpihdine TP2CN, the spectrum that records the intensity of the emission as a function of the wavelength of the emitted light can be seen, where the different curves correspond to different amounts of lithium added to the composite functionalized with TP2CN.

[0106] The black line in the spectrum corresponds to the composite with TP2CN without the addition of L¡ + , the first addition of 5 pL of a 0.04 mM solution of L¡ +, is represented by the red line. Subsequently, volumes of the L¡ solution were successively added. + , up to 180 pL (represented by the green line). It is observed that, as the lithium concentration increases, the fluorescence of 4'-(4-cyanophenyl)-2,2':6',2"-terp¡hd¡na (TP2CN) decreases, which is explained by the union of both compounds (terp¡hdine and lithium), generating changes in the structure of terp¡hdine, which is reflected in the gradual decrease in fluorescence with the addition of lithium.

[0107] For their part, figures 15 and 17 refer to the same previous terpihdines (TP2 and TP2CN), where the addition of lithium is shown for each case:

[0108] • 4'-phenyl -2,2':6',2"-terpyridine (TP2) (figure 15).

[0109] • 4'-(4-cyanophenyl)-2,2':6',2"-terpyridine (TP2CN) (Figure 17).

[0110] Figure 15 shows a spectrum that records the emission intensity as a function of lithium ion concentration, in order to observe the decrease in fluorescence of 4'-phenyl-2,2':6',2"-terpyridine (TP2) with the addition of lithium, until reaching saturation, where the fluorescence intensity no longer varies and remains around 0.4 ua. Figure 17 (similar to Figure 15, but for terpyridine TP2CN) shows a spectrum that records the emission intensity as a function of lithium ion concentration, in order to observe the decrease in fluorescence of 4'-(4-cyanophenyl)-2,2':6',2"-terp¡hd¡ne (TP2CN) with the addition of lithium, until reaching saturation, around a value of 0.4 ua.

[0111] Use of terpyridines as part of mesoporous materials to selectively bind lithium in a brine solution

[0112] Terpyridines alone selectively bind lithium. To incorporate these molecules into some of the industrial lithium purification procedures, generically referred to as selective purification processes, the present invention demonstrates that terpyridines bound to mesoporous materials such as aluminosilicates, plastics, carbon, clays, or MOFs (Metal Organic Frameworks), defined as materials with a large surface area, maintain their selective lithium-binding properties, but now in the form of composites that can be used in industrial scale-ups.

[0113] Characterization of mesoporous material composites with terpyridines

[0114] In figures 19 and 20, examples of infrared spectra of aluminosilicate not functionalized with terpyridines (figure 19) and aluminosilicate functionalized with terpyridine (figure 20) can be seen. The change in the spectrum that indicates the functionalization of the surface by the presence of terpyridine can be noted. This change is observed at 1040 cm. -1 , which indicates the disappearance of the Si-O bond, due to the union of terpyridines and therefore functionalization.

[0115] From now on, a functionalized composite will be called that mesoporous material that is bound to one or more terpyridines and a non-functionalized composite will be called that mesoporous material not bound to one or more terpyridines.

[0116] The graph in Figure 19 relates absorbance (transmittance) to frequency or wavelength. This spectrum is a measure of the fundamental vibrations and the rotational-vibrational structure associated with each molecule, in this case, the asymmetric stretching of silicon OS¡-0, which appears at 1040 cm -1 , serves to identify the non-functionalized composite created, since this asymmetric stretching is characteristic of mesoporous materials based on silicon oxide such as aluminosilicates.

[0117] The graph in Figure 20 relates absorbance (transmittance) to frequency or wavelength. This spectrum is a measure of the fundamental vibrations and the rotational-vibrational structure associated with each molecule; in this case, the disappearance of the asymmetric silicon O-Si-O stretching band that previously appeared at 1040 cm -1, serves to determine that the created composite is effectively functionalized on its surface by terpyridines.

[0118] For its part, Figure 18 shows the aluminosilicate mixture in the three stages of the reaction, where the differences in coloration show at first glance the change in the surface of the zeolite (as a mesoporous material) when it is functionalized with terpyridine and then when it binds to lithium. The photograph on the left corresponds to the mesoporous material suspended in water / ethanol, the photograph in the center corresponds to the mesoporous material after reacting with terpyridine (i.e., the functionalized mesoporous material), and the photograph on the right corresponds to the functionalized mesoporous material after reacting with lithium. Thus, the variation in the color of the mesoporous material can be clearly seen when going from a non-functionalized state to a functionalized state and finally to a functionalized state bound to lithium.

[0119] More clearly, the changes in the color of the formed composite are attributed to the binding of terpihdine to the surface of the material, changing from a light brown color to a pink hue (corresponding to the functionalized composite). Upon adding lithium, a new conformation of the composite structure is generated, reflected in a further color change to a violet hue. This means that the reaction can be easily monitored indirectly through color changes alone, which is very important for an industrial process, where the lithium bonding to the functionalized composite is evident at a glance.

[0120] First, a solution of the aluminosilicate (as a mesoporous material) is prepared in enough water to exceed the solid level, leaving the light brown powder in suspension. Then, it is made to react with the terpyridine for 24 hours at room temperature, with constant stirring, obtaining a pink-colored terpyridine-functionalized composite, which is then dried and characterized by SEM-XRD and fluorescence techniques. To bind the lithium, a solution of the functionalized composite is prepared in enough water to exceed the solid level, leaving the pink powder in suspension, LiCl is added (in a 1:1 ratio with the functionalized composite) and allowed to react for 48 hours at room temperature, with constant stirring, obtaining a violet-colored product, corresponding to the functionalized composite bound to lithium.The differences are evident, allowing the control of the reactions between the composite alone, the functionalized composite, and the functionalized composite bonded to lithium, as an indicator, and thus being able to control the lithium binding and release reaction by direct observation of color changes or indirect observation through the use of spectrophotometers. Figure 21 shows examples of infrared spectra of terpihdines bonded to aluminosilicates, that is, the functionalized composite alone (black line) and in the presence of lithium (red line), where the most significant change corresponds to the 2400 cm region. -1 , since the CN vibrations of terpihdine are lost, reflecting its binding to lithium.

[0121] This graph relates absorbance (transmittance) to frequency or wavelength. When both spectra are superimposed, it can be seen that the greatest change occurs in the 2400-2500 cm range. -1, where the band of aromatic heterocycles containing nitrogen disappears due to the union with lithium (the band at - 3500 cm -1 corresponds to the OH band of water, since the sample was not completely dry).

[0122] In figures 22 (a and b), the excitation (a) and emission (b) spectra can be seen for both the functionalized composite alone (black line) and for the functionalized composite bonded to lithium (red line).

[0123] In Figure 22 a), the black line represents the excitation spectrum for the functionalized composite alone, which has a maximum (7.0 x 10 5 ua) at 287 nm; similarly the lithium-bonded functionalized composite (red line) has a maximum (of 1.8 x 10 6 ua) at the same wavelength, i.e. at 287 nm, both spectra present a shoulder at 316 nm.

[0124] In Figure 22 b), the black line corresponds to the emission spectrum of the functionalized composite alone, and the red line corresponds to the emission spectrum of the functionalized composite bound to lithium, both presenting their maximum (4.0 x 10 5 ua and 1,2 x 10 6ua, respectively) at 367 nm. In these emission spectra, the emission intensity is recorded as a function of the wavelength of the emitted light, the excited molecule loses excess energy radiatively, and in this case it does so through fluorescence. We can see that there is no difference in the wavelength where the emission maximum occurs between the functionalized composite alone and the functionalized composite bound to lithium, but a large increase in the fluorescence intensity is noted when the functionalized composite is bound to lithium, because when lithium enters the terpihdine cavity, it must accommodate its structure, restricting its movements and becoming more rigid, which explains this increase.

[0125] Just as important as the selective binding of lithium to terpyridines alone and to the terpyridine composite is its release for subsequent commercialization.

[0126] This is why the present invention carries out the release of lithium bound to the terpihdines alone or bound to the functionalized composites at the nanometric or micrometric scale, through changes in pH, in order to be able to use the lithium later in various industrial applications.

[0127] Calculations of the effect of pH on the binding of terpihdines alone or in the form of functionalized composites.

[0128] A computational study, with molecular dynamics to determine the behavior of terpyridines at different pH, exploring the conditions under which they could have a higher performance in lithium uptake and its subsequent release, can be seen in Figure 23. Where the nitrogens of the tridentate part of the terpyridines have the ability to maintain different conformations, depending on the pH at which they are found, so that by titrating the terpyridine, specific information can be obtained from the pH at which the presence of each of the species will be possible.The four possible terpyridine species were modeled computationally depending on the pH, where E1 corresponds to the deprotonated terpyridine species, which corresponds to the structure with the greatest capacity for interaction with the metal, in this case lithium, since the electron pair of each nitrogen in the cavity is available for interaction. On the other hand, species E2 and E3 are partially protonated species, which, due to the fact that they have the H. + In the cavity, the possibilities of interaction with the metal are drastically reduced. Finally, the E4 species, being completely protonated, has no possibility of interacting with the metal, due to the stethic hindrance generated by the H + bonded to the nitrogen atoms in the cavity, so the possibility of metal bonding is zero. Therefore, the "affinity" of each terpyridine species at different pHs is shown in the following table:

[0129] E1 > E3 > E2 > E4

[0130] Figure 24 shows a graph of the distribution of terpyridine microspecies with respect to pH. Terpyridine titration was performed to predict the pKa at which the different species shown in Figure 23 exist and coexist, and to obtain the pH values ​​at which each structure will have the greatest metal-binding capacity and will also be able to release it.

[0131] Synthesis of functionalized composites of the invention:

[0132] To a mesoporous support such as activated carbon, silica, alumina, aluminosilicate, MOF and some metal oxides such as niobium, tantalum, titanium, zirconium, cene and tin, used in existing processes for the purification of L¡ compounds and other metals, ethanol, water and / or ammonia are added, so as to cover the amount of mesoporous support. Subsequently, a first stirring is carried out at room temperature. Once the sample is dispersed, one or more of the following terpyridines are added: 4'-phenyl-2,2':6',2"-terpyridine, 4'-(4-hydroxyphenyl)-2,2':6',2"-terpyridine, 4'-(4-cyanophenyl)-2,2':6',2"-terpyridine and 4'-(4-carboxyphenyl)-2,2':6',2"-terpyridine. The solution is stirred for a second time at room temperature, resulting in a mesoporous material functionalized with terpyridines, known as a functionalized composite or terpyridine-functionalized particle matrix (TPFM).

[0133] To obtain 1 g of functionalized composite, the quantities or proportions of each of the components are:

[0134] The percentage of mesoporous support varies from 90 to 98% of the total mass of the composite.

[0135] The amount of ethanol varies between 2.5 mi and 7.5 mi, preferably 5 mi.

[0136] The amount of water varies between 10 mi and 20 mi, preferably 15 mi.

[0137] The ammonia concentration is 20 to 30% by weight, preferably 25% by weight.

[0138] The time of the first stirring varies between 1 hour and 8 hours, preferably 6 hours.

[0139] The ambient temperature varies between 20°C and 25°C.

[0140] The proportion of 1 or more terpyridines in the case of more than one is 10% to 20% of each of the terpyridines in the mixture.

[0141] The time of the second stirring varies from 1 to 8 hours, preferably 6 hours.

[0142] Characterization of the mesoporous material to be used in the composite:

[0143] Chemical analysis (SEM): Chemical analysis was performed using a scanning microscope with an X-ray detector (SEM-EDS), which has a sensitivity of 200 ppm. This system allows the capture, acquisition and processing of high-resolution primary and secondary electron images for solid materials. With this system, images of all samples were captured, semi-quantitative chemical composition analyses were performed and elemental maps were obtained. The results obtained from the chemical analysis performed on the mesoporous material used in the invention are shown below: Table 1: Summary of chemical analysis obtained by SEM for mesoporous material used.

[0144] The results of scanning microscopy for the elements detected according to Table 1 can be seen in the graph in Figure 25. The EDS software compares the measured energies with specific elements that may be present in the material and proposes a qualitative list of those elements and their relative amounts within the material. X-ray diffraction:

[0145] To semi-quantitatively determine the crystalline phases present in the different samples, an X-ray diffraction analysis was performed, a technique that uses the interference of an X-ray beam with the crystalline network of the samples present in the materials, where the results shown in figure 26 and tables 2 and 3 below were obtained.

[0146] Table 2: Identification of crystalline phases, with normalized quantitative semi-linearity (SQ).

[0147] Table 2 was normalized to 100% of the crystalline phase areas; the amorphous mass is normalized to the crystalline areas of the phases present. The colors indicated for each identified compound are in turn represented in the diffraction diagram in Figure 26.

[0148] The diffractogram or diffraction profile measured from the sample of the mesoporous material used is shown in Figure 26 and corresponds to the reflection data of the sample and is represented in black, while the contribution to the diffractogram of the phases or compounds identified according to the data indicated in Table 2 appears in different colors. Table 3: Calculated crystallinity for the chosen mesoporous material.

[0149] Infrared (IR) spectroscopy:

[0150] The results of infrared (IR) spectroscopy are shown in Figure 19, where the asymmetric stretching band of silicon O-Si-O at 1040 cm can be seen.-1 characteristic of mesoporous materials such as zeolite and aluminosilicates.

[0151] Characterization of the functionalized composite (MPFT):

[0152] Infrared (IR) spectroscopy:

[0153] After the synthesis of the functionalized composite, it was characterized by infrared spectroscopy (IR), shown in Figure 20 where the disappearance of the band at 1040 cm -1 , indicates that the vibrations of the Si-O bond no longer exist, due to the union with the terpihdines and therefore the functionalization.

[0154] The resulting composite, known as MPFT, has surprising properties with respect to its high selective affinity for Li, allowing its recovery at concentrations of parts per million. It is also surprising that it does not bind to other types of ions. Lithium, sodium, and potassium belong to the same periodic table, so one would expect them all to have the same affinity, which is not the case. These properties are the surprising advantage of the present invention over the prior art.

[0155] Size analysis:

[0156] Figures 27a and 27b show SEM images of the agglomerated composite particles with a nanometric size of 20 nm (Figure 27a) and a micrometric size of 50 µm (Figure 27b). These images show the size and composition of the material. The images confirm that the majority of the MPFT has a particle size smaller than 1 µm.

[0157] Chemical analysis (SEM): The following Table 4 shows the results obtained from the chemical analysis carried out on the functionalized composite of the invention, performed using a scanning microscope with X-ray detector (SEM-EDS), which has a sensitivity of 200 ppm.

[0158] Table 4: Summary of chemical analysis obtained by SEM for functionalized composite

[0159] Binding of MPFT to metal ions present in brines

[0160] The brines used come from salt flats and from lithium extraction from rock deposits. A molecular study of the interaction between the MPFT of the invention and the Li cations was performed. + , Na + and K + , in order to see the affinity and selectivity of the MPFT with respect to said cations.

[0161] Table 5 shows the thermodynamic energy results for the macromolecular compounds formed between MPFT-Me, where Me = the cations studied. In general terms, a negative value for AE, AH, and AG indicates that the reaction or process is exothermic, meaning that energy is released in the form of heat. Conversely, a positive value indicates that the reaction or process is endothermic, meaning that an energy input is required for its completion. Therefore, the more energy released implies that the compound is more stable and forms more spontaneously. Meanwhile, the more energy required for the formation of said compound implies that it is not a spontaneous formation.

[0162] Table 5: Thermodynamic values ​​for the MPFT-Me interaction, where Me=L¡ + , Na + and K + .

[0163] When comparing the values ​​of AE, AH and AG among the cations L¡ +, Na + and K + , it can be observed that the cation of L¡ + experiences the greatest change in energy, suggesting that L¡+ undergoes a more significant reaction or process than Na + and the K + . Furthermore, the values ​​of AH and AG for L¡+ are also the most negative, suggesting that the reaction or process is exothermic and spontaneous.

[0164] On the other hand, the Na + and the K + They experience smaller energy changes compared to L¡+, suggesting that the reactions or processes occurring are less significant. Although they are still exothermic and spontaneous (negative AH and AG values), the energy changes are less pronounced.

[0165] Overall, the results indicate that L¡ + is the most reactive, undergoing a more significant reaction or process, while Na + and the K +They are less reactive or undergo less significant reactions or processes.

[0166] Through a classical computational simulation, these energy data can be obtained, allowing us to quickly interpret the affinity results, serving as an international standard for representing these assays.

[0167] Completion capacity between MPFT and lithium

[0168] A MPFT was obtained using 4'-(4-phenyl)-2,2':6',2"-terpihd¡ne according to the synthesis process explained above.

[0169] This MPFT was tested as follows:

[0170] Fluorescence:

[0171] Fluorescence spectra were performed on a Spex Fluorolog 1681 using an excitation of 280 nm (3 nm slit) for emission of 325-450 nm (3 nm slit). Successive additions of L¡ were performed for the measurements. + 5 pL each time.

[0172] For example, the graph in Figure 16 shows the variation in fluorescence intensity versus wavelength for a complex obtained between the MPFT indicated above and lithium, where each of the curves corresponds to the successive addition of 5 pL of lithium chloride solution with a concentration of 0.04 mM to the initial terpihdine solution of 15 pM.

[0173] The graphs in Figures 14-17 show the variations in the fluorescence intensity of the composite functionalized with the specified terpihdine (TP2 and TP2CN) and lithium, versus the lithium concentration. It can be seen that by adding small concentrations of Li +, the intensity of the fluorescence decreases, which accounts for the complexing capacity between terpihdine and lithium, since as the fluorescence intensity of the terpihdine decreases, the formation of a new compound is recorded. The process of fluorescence decrease, also known as quenching (fluorescent deactivation which refers to any process that produces a decrease in the intensity of the fluorescence emitted by a certain substance), produced by binding lithium to terpihdine, is of utmost importance, since terpihdines also function as luminescent chemosensors (molecules that experience a change in their luminescence, when reacting or binding with another) for lithium.

[0174] These experiments show that the MPFTs of the invention are capable of binding between 15 - 50 mg of lithium for each gram of terpihdine present in the MPFT.

[0175] In the semi-quantitative EDS analysis, shown in Figure 28, the appearance of a strong signal for CT is observed, which does not appear in the analysis performed on the composite alone (Figure 25), which is directly related to the amount of lithium bound to the composite. In Figure 28 no trace elements were observed. The following Table 6 shows the results obtained from the chemical analysis performed on the functionalized composite of the invention bound to lithium, carried out using a scanning microscope with X-ray detector (SEM-EDS), which has a sensitivity of 200 ppm. Table 6: Summary of chemical analysis obtained by SEM for functionalized composite bonded to Lithium.

[0176] In order to verify the amount of lithium bound to the MPFT (functionalized composite), a calibration curve for CT was created, which is used to indirectly calculate the amount of lithium present, using the mass percentages of each ion in the compound used (LiC I). The average of the 4 measurements taken was 18.82%, thus allowing the lithium concentration per gram of matrix to be obtained through a calibration curve developed for CT (Figure 29). The calculated value was 36.8 mg of Li / 1 g of MPFT. This indicates that the functionalized composite is capable of capturing 36.8 mg of lithium from the brine, per gram of said functionalized composite. To obtain the graph in Figure 29, the following data were used for its construction:

[0177] Furthermore, as previously explained, through computational calculations of semiempihcal Tight Binding molecular dynamics, thermodynamic parameters (from Table 5) were obtained which suggest that terpihdine has a greater affinity for the L¡ ion. + than the other Na ions + and K + The simulation summarized in Figure 30 shows how the lithium ion (green in the figure) spontaneously adds to the terpyridine binding site, attracted by the nitrogens (blue in the figure) arranged inside the tridentate cavity of the terpyridine.

[0178] Purification of lithium from laboratory-prepared artificial brines:

[0179] A brine composition was prepared like those reported for the Atacama salt flat, the brine is composed of: 0.2% Li, 1% Mg, 2% K, 7% Na, 0.05% Ca and 15% Cl.

[0180] The brine was in contact with the MPFT for 48 hours at a controlled temperature of 25 °C, using mechanical stirring. The product formed was immediately analyzed by fluorescence spectroscopy and X-ray diffraction, in order to confirm the formation of the complex between the MPFT and the lithium in the brines. The increase in the fluorescence of the MPFT is detected as lithium is incorporated, without presenting a significant interaction with the rest of the ions present in the brine solution. Subsequently, to release the lithium from the complex formed with the MPFT, the solution is acidified using 1 N sulfuric acid until the necessary pH is achieved to produce the release of between 80% and 95% of the lithium captured by the MPFT.

[0181] Figure 23 shows the different protonated and deprotonated species, where the species that has the greatest affinity and retention for lithium corresponds to the deprotonated species (E1), then with less affinity the protonated species with 2 H + (E3) and 1 H + (E2) and finally the fully protonated species (E4), according to the following table:

[0182] E1 > E3 > E2 > E4

[0183] Meanwhile, in Figure 24, the pKa value near 4 in a nitrogen-containing ring suggests that the compound is a weak acid and that the nitrogen in the ring contributes to its acid-base behavior.

[0184] These results prove that at a pH above 5, the completely deprotonated species, which has the greatest affinity for Li, mostly exists, which means that at a pH above 5 there will be an effective binding to lithium, and that, at a pH below 5, the terpyridine of the composite will begin to protonate so that the affinity for Li will be increasingly lower, a phenomenon that will be used to recover Li.

[0185] Obtaining lithium from brines:

[0186] The functionalized composite produced according to the conditions mentioned above together with the brine containing ions of lithium, magnesium, potassium, sodium, calcium and chlorine among others (with the following concentrations: 0.2% Li, 1% Mg, 2% K, 7% Na, 0.05% Ca and 15% Cl) is placed in a container (A) with mechanical stirring for at least 48 hours at a controlled room temperature between 20 ° C and 25 ° C, forming a solution (3) with the complex (4) between the MPFT and the lithium. Subsequently, the solution (3) comprising the complex between the MPFT and the lithium is taken to a first metallic column or cartridge (1), for a residence time period t1 , inside which there is a filter bag (2) and through which said solution (3) is passed, as shown in figure 31 .

[0187] The residence time t1 in the first filtration column (1) varies between 45 and 50 hours, preferably 48.

[0188] The complex formation process continues to be carried out in the first filtration column (1 ), this can be monitored by various techniques such as ICP (Inductively Coupled Plasma Spectroscopy) or by fluorescence or by change in the colour of the MPFT, taking samples at each stage, until no significant variations in the measurement occur. By ICP, it is observed that the lithium concentration does not vary, by fluorescence that equilibrium has been reached or that the fluorescence no longer varies as more lithium is added and by change in colour by direct observation when a violet hue is reached or by indirect observation by spectrophotometry.

[0189] Once the doping or saturation of the MPFT with lithium has been reached (approximately a 70% decrease in fluorescence, Figure 16), the lithium is released through acidification (5) with a strong acid such as hydrochloric acid or sulfuric acid in a second filtration column (1) for a residence time t2 of 2 to 6 hours, preferably 4 hours, obtaining a lithium recovery of between 95% and 99% in the form of Li2CO3(7), by adding Na2CO3(6) in a ratio of 1:1 of the functionalized composite to sodium carbonate to obtain lithium carbonate (see Figure 32).

[0190] Other systems currently in use, such as those described in the prior art, have lower affinity and selectivity than the one proposed in the present invention, since the composite of the invention requires less water and acid and can also replace these materials in all systems currently designed for lithium purification. Advantages:

[0191] The advantages that can be appreciated from the present invention can be summarized as follows:

[0192] > Reduction in lithium extraction time.

[0193] > Reduction in processing costs. > Reduction in water use, between 20% and 80%.

[0194] > Reduction in physical space compared to evaporation pools.

[0195] > Reduction of environmental impact.

Claims

CLAIMS 1. A more efficient lithium recovery process from brines, with a reduction in recovery times and environmentally friendly, CHARACTERIZED because it includes: - preparing a terpihdine-functionalized composite comprising: • provide a mesoporous support selected from activated carbon, silica, alumina, aluminosilicate, MOF and oxides of niobium, tantalum, titanium, zirconium, cerium and tin; • add ethanol, water and / or ammonia, so as to completely cover the mesoporous support; • perform a first stirring of the mixture at room temperature, until the mixture is dispersed; • add one or more terpihdines; • perform a second stirring of the mixture formed at room temperature; • obtain a composite functionalized with terpihdine (MPFT: matrix of particles functionalized with terpihdine); - contacting a brine with MPFT in a vessel with mechanical stirring for at least 48 hours to form a MPFT-lithium complex; - carrying the solution with the MPFT-lithium complex to a first filtration column for a residence time period (t1); - control the process until the MPFT is saturated with lithium; - acidifying the MPFT-lithium complex with a strong acid in a second filtration column for a second residence time period (t2) to release the lithium; - adding sodium carbonate (Na2COs) to the solution of the acidified complex comprising lithium to obtain lithium in the form of lithium carbonate (L^COs).

2. The process according to claim 1, CHARACTERIZED in that in the preparation stage of the functionalized composite, to obtain 1 gr of functionalized composite, the amount of mesoporous support varies between 90-98% of the total mass of the composite.

3. The process according to claim 1, CHARACTERIZED in that in the preparation stage of the functionalized composite, to obtain 1 g of functionalized composite, the amount of ethanol varies between 2.5 ml and 7.5 ml, preferably 5 ml.

4. The process according to claim 1, CHARACTERIZED in that in the preparation stage of the functionalized composite, to obtain 1 g of functionalized composite, the amount of water varies between 10 ml and 20 ml, preferably 15 ml.

5. The process according to claim 1, CHARACTERIZED in that in the preparation stage of the functionalized composite, to obtain 1 g of functionalized composite, the concentration of ammonia is 20 to 30% by weight, preferably 25% by weight.

6. The process according to claim 1, CHARACTERIZED in that in the preparation stage of the functionalized composite the time of the first and second stirring varies between 1 hour and 8 hours, preferably 6 hours.

7. The process according to claim 1, CHARACTERIZED in that in the preparation stage of the functionalized composite the ambient temperature varies between 20°C and 25°C.

8. The process according to claim 1, CHARACTERIZED in that in the preparation step of the functionalized composite the one or more terpihdines are selected from: 4'-phenyl-2,2':6',2"-terp¡hd¡na, 4'-(4- hydroxyphenyl)-2,2':6',2"-terpyridine, 4'-(4-cyanophenyl)-2,2':6',2"-terpyridine and 4'-(4-carboxyphenyl)-2,2':6',2"-terpyridine.

9. The process according to claim 1, CHARACTERIZED in that in the preparation stage of the functionalized composite, to obtain 1 g of functionalized composite, the proportion of terpyridines in the event that there are more than one is 10% to 20% of each of the terpyridines in the mixture.

10. The process according to claim 1, CHARACTERIZED in that the brine mainly comprises lithium, magnesium, potassium, sodium, calcium and chlorine.

11. The process according to claim 1, CHARACTERIZED in that the step of contacting a brine with the MPFT is carried out at a controlled ambient temperature of 20°C to 25°C.

12. The process according to claim 1, CHARACTERIZED in that the residence time period (t1) in the first column is 45 to 50 hours, preferably 48 hours.

13. The process according to claim 1, CHARACTERIZED in that the control step until reaching the saturation of the functionalized composite-lithium complex is carried out by means of ICP (Inductively Coupled Plasma Spectroscopy), fluorescence or color change of the MPFT.

14. The process according to claim 13, CHARACTERIZED in that when the control is carried out by ICP, the contact stops when the concentration of lithium analyzed is unchanged.

15. The process according to claim 13, CHARACTERIZED in that when the control is carried out by fluorescence, the contact is stopped when the fluorescence is found without variation as when more lithium is added to the column or when a 70% decrease in initial fluorescence has been reached.

16. The process according to claim 13, CHARACTERIZED in that when the control is carried out by change in coloration, the contact stops when the MPFT is violet in color.

17. The process according to claim 1, CHARACTERIZED in that the acidification is carried out with a strong acid with concentrations of 1 M, selected from hydrochloric acid or sulfuric acid, wherein the second residence time period (t2) is between 2 and 6 hours, preferably 4 hours.

18. The process according to claim 1, CHARACTERIZED in that in the step of adding sodium carbonate (Na2COs) to the solution of the acidified complex comprising lithium to obtain lithium in the form of lithium carbonate (IJ2CO3), it is carried out in a 1:1 ratio of the functionalized composite to sodium carbonate.

19. The process according to claim 1, CHARACTERIZED in that the brine is natural or artificial.

20. A composite functionalized with terpihdine, CHARACTERIZED in that it comprises: - a mesoporous support selected from activated carbon, silica, alumina, aluminosilicate, MOF and oxides of niobium, tantalum, titanium, zirconium, cene and tin; - one or more terpihdines; - which presents a % transmittance at 1040 cm -1 between 70% and 80%; - which presents a % transmittance in the range of 2400 - 2500 cm -1 of 98%; and - comprising the following elements: O, Na, Mg, Al, Si, Cl, K, Ca and Fe.

21. The terpyridine-functionalized composite according to claim 20, CHARACTERIZED in that the proportion of terpyridines in the event that there are more than one is 10% to 20% of each of the terpyridines in the mixture.

22. The terpyridine-functionalized composite according to claim 20, CHARACTERIZED in that the one or more terpyridines are selected from 4'-phenyl-2,2':6',2"-terpyridine, 4'-(4-hydroxyphenyl)-2,2':6',2"-terpyridine, 4'-(4-cyanophenyl)-2,2':6',2"-terpyridine and 4'-(4-carboxyphenyl)-2,2':6',2"-terpyridine.

23. The terpyridine-functionalized composite according to claim 20, CHARACTERIZED in that the particle size of the composite is less than 1 µm.

24. The terpyridine-functionalized composite according to claim 20, CHARACTERIZED in that the elements are present in the following mass percentages: - 0: 50.05 - 52.87 - Na: 1,64 - 2,16; - Mg: 0.02 - 0.25; - Al: 7.12 - 7.49; - Yes: 30.85 - 32.66; - Cl: 0.84 - 2.94; - K: 0.91 - 1.38; - Ca: 2.76 - 3.85; - Fe: 1 ,38 - 1 ,87.

25. The terpyridine-functionalized composite according to claim 20, CHARACTERIZED in that it has selective affinity for lithium.

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