An apparatus and method for desorption of manganese-based ion sieves

Abstract

This invention relates to an apparatus and method for desorption of manganese-based ion sieves. The method involves filling the ion exchange chamber with adsorbed manganese-based ion sieves, adding aqueous solutions to the anode and ion exchange chambers, and adding a salt solution to the cathode chamber. A power supply is turned on, and the voltage is adjusted to generate 0.001–0.1 mol / L H₂ in the anode chamber. + H + The cation exchange membrane passes through the ion exchange chamber, where it undergoes an ion exchange reaction with the manganese-based ion sieve. Water samples are periodically taken from the anode chamber, cathode chamber, and ion exchange chamber to detect Li. + Concentration, Mn 4+ By determining the concentration, pH, and conductivity, the critical points of ion exchange desorption sites and redox desorption sites are identified, and the reaction is controlled to ensure the desorption of the manganese-based ion sieve. Compared with existing technologies, this invention uses water electrolysis under a DC electric field to prepare a dilute acid regeneration solution, regenerating lithium ions at the ion exchange sites of the manganese-based ion sieve, achieving the goal of identifying desorption sites and minimizing manganese loss during low-concentration hydrogen ion regeneration.

Description

Technical Field

[0001] This invention relates to the field of manganese-based ion sieve regeneration technology, and in particular to an apparatus and method for desorption of manganese-based ion sieves. Background Technology

[0002] The rise of portable electronic devices and electric vehicles has driven a strong demand for lithium. Lithium-ion sieve adsorption methods offer higher selectivity and adsorption capacity due to their inherent adsorption capabilities. However, the manganese loss during acid desorption remains unresolved. Although intrinsic control methods such as interface engineering, elemental doping, and morphology control have reduced some loss during acid desorption to a certain extent, the problem is not completely solved. Acid washing and regeneration methods for manganese-based ion sieves have many drawbacks, such as high acid concentration and low utilization rate, environmental pollution from waste acid discharge, complex regeneration operations, the need for safe storage and transportation of the acid as a hazardous chemical, and poor working conditions.

[0003] After the granulated manganese-based ion sieve adsorbs saturated lithium ions, it needs to undergo a continued adsorption-desorption cycle. The traditional chemical desorption method involves regenerating the manganese-based ion sieve with pre-prepared 0.5-3M nitric acid, hydrochloric acid, or sulfuric acid. This regeneration method often results in a hydrogen ion-lithium ion exchange rate exceeding 90% due to the strong hydrogen ion concentration, leading to excessive desorption of lithium ions from redox reaction sites and a 2-6% manganese loss rate. In traditional acid desorption, it is difficult to control the desorption sites. Firstly, the volume occupied by dilute acid is large, and secondly, it is difficult to control the desorption time. After multiple adsorption / desorption cycles, manganese loss gradually accumulates, eventually causing damage to the ion sieve structure. Traditional chemical desorption methods use strong acids, and the solution contains H... + The concentration is basically the same as the acid concentration, therefore the H2O of the acid solution is directly reduced. + The concentration is insufficient to provide enough H+. + The ion sieve precursor is desorbed. This invention investigates whether an applied electric field can effectively modulate the desorption site recognition ability. There are two possible mechanisms: one is that the electric field effectively enhances the ability to detect trace amounts of H+. + Diffusion and mass transfer in Li-Mn-O compounds make desorption under weak acid conditions possible; secondly, the application of potential changes the H+. + Desorption site, H + Li acting only on ion exchange sites + Instead of Li at redox sites + Li-Mn-O compounds do not undergo disproportionation during desorption; instead, they undergo only ion exchange.

[0004] Therefore, there is an urgent need to develop a new device and method for regenerating manganese-based ion sieves to achieve the goal of identifying desorption sites and minimizing manganese loss during the regeneration of ion sieves with low concentrations of hydrogen ions.

[0005] Patent publication number CN115522071B discloses an apparatus and method for activating an electrode. The apparatus includes an anode chamber, a cathode chamber, and a diaphragm; a salt solution is disposed in the anode chamber; a conductive electrode is disposed in the cathode chamber; and an oxidant solution is disposed in the cathode chamber. However, in this apparatus, a manganese-based ion sieve membrane electrode or a lithium iron phosphate membrane electrode is used as the electrode to be activated for lithium desorption.

[0006] Patent publication number CN115404357A discloses a method for separating lithium and sodium, comprising the following steps: S1. Adding electrode solution to the anode and cathode chambers of a bipolar membrane separation device; S2. Adding adsorbent to the first salt chamber of the bipolar membrane separation device and adding water to the second salt chamber of the bipolar membrane separation device; S3. Adding a mixture containing lithium ions and sodium ions to the first salt chamber and allowing it to stand for a period of time; S4. Collecting the solution in the first salt chamber; S5. Injecting a solution containing lithium ions into the first salt chamber; S6. Powering the bipolar membrane separation device; S7. Collecting the solution in the second salt chamber. This method generates hydrogen ions through bipolar membrane electrolysis of water, achieving the desorption of adsorbed lithium ions by the adsorbent, without the need for additional acids or alkalis, but without addressing the issue of adsorbent degradation. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects of the prior art by providing an apparatus and method for desorption of manganese-based ion sieves. A dilute acid regeneration solution is prepared by electrolysis of water under the action of a DC electric field. The dilute acid regeneration solution is used to regenerate lithium ions at the ion exchange sites of the manganese-based ion sieve, thereby achieving the goal of identifying desorption sites and minimizing manganese loss during the regeneration of ion sieves with low concentrations of hydrogen ions.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] In one aspect, the present invention provides an apparatus for desorption of manganese-based ion sieves, comprising:

[0010] The anode chamber, which has a positive electrode, is filled with a substance that can be electrolyzed to generate a low concentration of H₂. + An aqueous solution, wherein the anode is connected to the positive terminal of a power source, generates a low concentration of H2O. + The concentration is 0.001–0.1 mol / L;

[0011] A cathode chamber having a cathode electrode connected to the negative terminal of a power source;

[0012] An ion exchange chamber is disposed between the anode chamber and the cathode chamber. The ion exchange chamber is separated from the anode chamber by a cation exchange membrane and from the cathode chamber by an anion exchange membrane. The ion exchange chamber is used to fill the adsorbed manganese-based ion sieve. The anode chamber contains H... + The manganese-based ion sieve is desorbed by entering the ion exchange chamber through the cation exchange membrane.

[0013] A direct current electric field is formed by passing electricity through the anode and cathode. After the electricity is applied, the aqueous solution in the anode chamber is polarized, causing a small amount of water to ionize and release a sufficient amount of H+. + A reduction reaction of metal ions occurs in the cathode chamber, and under the action of an external electric field, H+ is generated at the anode. + Selective migration occurs promptly, passing through the cation exchange membrane into the ion exchange chamber to obtain a regenerated solution.

[0014] Furthermore, the aqueous solution filling the anode chamber includes deionized water, 0-0.05 mol / L H2SO4 aqueous solution, 0-0.1 mol / L HCl aqueous solution, 0.01-5 mol / L Na2SO4, and 0.01-5 mol / L NaCl;

[0015] The cathode chamber contains a salt solution, including a 1%–5% CuCl2 aqueous solution, 0.01–5 mol / L Na2SO4, 0.01–5 mol / L NaCl, NaH solution, and various oxidants (Fe2+). 2+ Fe 3+ Cu 2+ Cu+, I2, I3 - Sn 4+ Cr 3+ Cd 2+ Pb 2+ PO4 3- V 3+ Sn 2+ HCOOH, HCHO, CH3OH, SbO + VO 2+ H2MoO4, MnO4 - 、Tl 3+ Ag + A solution of at least one of the following;

[0016] The ion exchange chamber is filled with an aqueous solution, including deionized water, 0–0.05 mol / L H₂SO₄ aqueous solution, 0–0.1 mol / L HCl aqueous solution, 0.01–5 mol / L Na₂SO₄, and 0.01–5 mol / L NaCl; wherein electrolyzed water can provide sufficient low concentrations of H₂SO₄.+ This regulates desorption sites and reduces manganese loss during ion sieve desorption. Low concentrations of H2SO4 or HCl aqueous solutions can further increase solution salinity, thus favoring the water electrolysis reaction.

[0017] Furthermore, the power supply is a DC power supply with a voltage of 1 to 20V, preferably 2 to 5V.

[0018] Furthermore, the manganese-based ion sieve includes LiMn2O4 and Li4Mn5O4. 12 Li 1.6 Mn 1.6 O4 or Li 1.33 Mn 1.67 O4.

[0019] Furthermore, the manganese-based ion sieve is granular, not powdery.

[0020] Furthermore, the anode includes at least one of the following: titanium electrode, iridium-titanium electrode, carbon electrode, graphite electrode, glassy carbon electrode, carbon felt electrode, platinum electrode, stainless steel electrode, copper electrode, silver electrode, aluminum electrode, and metal alloy electrode.

[0021] The cathode electrode includes at least one of the following: titanium electrode, carbon electrode, graphite electrode, glassy carbon electrode, carbon felt electrode, platinum electrode, stainless steel electrode, copper electrode, silver electrode, aluminum electrode, and metal alloy electrode.

[0022] The cation exchange membrane includes ordinary cation exchange membrane, monovalent cation exchange membrane, and divalent cation exchange membrane;

[0023] The anion exchange membrane includes a common cation exchange membrane, a monovalent cation exchange membrane, and a divalent cation exchange membrane.

[0024] Furthermore, a first outlet is provided on one side of the anode chamber and a first inlet is provided on the top. A first circulation pump is connected between the first outlet and the first inlet to realize the circulation of the aqueous solution in the anode chamber.

[0025] A second water outlet is provided on one side of the cathode chamber, and a second water inlet is provided on the top. A second circulation pump is connected between the second water outlet and the second water inlet to realize the circulation of the aqueous solution in the cathode chamber.

[0026] A third outlet is located on one side of the ion exchange chamber, and a third inlet is located at the top. A third circulation pump connects the third outlet and the third inlet to achieve the circulation of the aqueous solution within the ion exchange chamber. The circulation of the solution between the anode chamber, cathode chamber, and ion exchange chamber improves the uniform distribution of electrolytes and enhances the efficiency of the electrochemical process. By introducing the circulation pump, the flow rate and direction of the solution within the system can be controlled, optimizing electrolyte transfer and thus achieving more precise and efficient ion exchange in the electrochemical process.

[0027] Furthermore, the anode chamber, cathode chamber, and ion exchange chamber are subjected to frequent and repeated periodic sampling to detect Li. + Concentration, Mn 4+ The concentration and conductivity are used to determine the critical points of ion exchange desorption sites and redox desorption sites, and to control the reaction so that the manganese loss of the manganese ion sieve is less than 0.02% and the adsorption capacity is greater than 12 mg / g.

[0028] Furthermore, a first clamping plate for fixing the anode is provided on the side of the anode electrode away from the anode chamber;

[0029] A second clamp is provided on the side of the cathode electrode away from the cathode chamber to fix the cathode electrode;

[0030] The first clamping plate, the anode, the anode chamber, the cation exchange membrane, the ion exchange chamber, the anion exchange membrane, the cathode, the cathode, and the second clamping plate are sequentially attached to each other and fixedly connected by several bolts.

[0031] Furthermore, the anode chamber has a first cavity filled with the aqueous solution, the cathode chamber has a second cavity filled with the salt solution, and the ion exchange chamber has a third cavity filled with the aqueous solution; the bolt is located around the periphery of the first cavity, the second cavity, and the third cavity.

[0032] Furthermore, the top of the ion exchange chamber is provided with several filling holes for filling the manganese-based ion sieve.

[0033] On the other hand, a method for desorption using a manganese-based ion sieve, implemented using the aforementioned apparatus, is characterized by comprising the following steps:

[0034] A1. Fill the ion exchange chamber with the adsorbed manganese ion sieve, add an aqueous solution to the anode chamber and the ion exchange chamber, and add a salt solution to the cathode chamber;

[0035] A2. Turn on the power and adjust the voltage to generate 0.001–0.1 mol / L H₂ in the anode chamber. + H +It passes through the cation exchange membrane into the ion exchange chamber and undergoes an ion exchange reaction with the manganese-based ion sieve to desorb metal ions;

[0036] A3. Periodically take water samples from the anode chamber, cathode chamber, and ion exchange chamber to detect Li. + Concentration, Mn 4+ Concentration, pH, and conductivity are used to determine the critical points of ion exchange desorption sites and redox desorption sites, and the reaction is controlled to ensure that the manganese-based ion sieve completes desorption.

[0037] Further, in step A1, the mass-to-volume ratio of the manganese-based ion sieve to the aqueous solution in the ion exchange chamber is 0.015-0.24 g / ml;

[0038] The aqueous solution filling the anode chamber includes deionized water, 0-0.05 mol / L H2SO4 aqueous solution, 0-0.1 mol / L HCl aqueous solution, 0.01-5 mol / L Na2SO4, and 0.01-5 mol / L NaCl.

[0039] The cathode chamber contains a salt solution, including one or more of the following: 1-5% CuCl2 aqueous solution, 0.01-5 mol / L Na2SO4, 0.01-5 mol / L NaCl, NaOH solution, or oxidant solution;

[0040] The oxidant solution includes Fe... 3+ Cu 2+ I2, I3 - Cr 3+ Cd 2+ Pb 2+ PO4 3- V 3+ HCOOH, HCHO, SbO + VO 2+ H2MoO4, MnO4 - 、Tl 3+ Ag + A solution containing at least one ion;

[0041] The ion exchange chamber is filled with an aqueous solution, including deionized water, 0-0.05 mol / L H2SO4 aqueous solution, 0-0.1 mol / L HCl aqueous solution, 0.01-5 mol / L Na2SO4 or 0.01-5 mol / L NaCl.

[0042] Furthermore, in step A2, the power supply is a DC power supply with a voltage of 0.1 to 20V;

[0043] H generated in the anode chamber+ The concentration was consistently maintained at 0.001–0.5 mol / L, and even further at 0.001–0.1 mol / L.

[0044] Furthermore, in step A3, the water samples taken from the anode chamber, cathode chamber, and ion exchange chamber are periodically taken for 10 to 60 minutes; even further, for 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, and 60 minutes.

[0045] The critical point between the ion exchange desorption site and the redox desorption site is when the manganese loss rate of the manganese-based ion sieve is less than 0.02% and the adsorption amount is greater than 12 mg / g. At this point, the manganese loss rate is very small and can be almost ignored. If the reaction time is increased further, the manganese loss rate increases rapidly while the increase in lithium ion desorption amount is not significant.

[0046] Further, in step A3, the reaction time is 10 to 60 minutes; more preferably, it does not include 60 minutes.

[0047] The reaction mechanism in the anode chamber is 2H₂O - 4e⁻ - =O2↑+4H + ;

[0048] The reaction mechanism of the cathode chamber is Cu 2+ +2e - =Cu.

[0049] Compared with the prior art, the present invention has the following advantages:

[0050] (1) The desorption reaction of manganese-based ion sieves includes H + Inter-ion exchange reaction with Mn 3+ In the disproportionation reaction, manganese loss mainly occurs at the disproportionation reaction sites. This invention continuously provides low-concentration H+ through water electrolysis. + , reduce H in the solution + By adjusting the concentration of lithium, controlling the desorption sites, and inhibiting the extraction of lithium from redox sites, lithium extraction can be carried out in manganese-based ion sieves. + This device effectively desorbs manganese while reducing manganese loss during the desorption process of the ion sieve. Cyclic desorption experiments were conducted on manganese-based ion sieves using this device, and the desorption rate was approximately 98%, with a manganese loss of only 0.02%.

[0051] (2) This device uses two electrodes, a cathode and a cation, added to both sides of a manganese-based ion sieve. The cathode and cation are separated from the manganese-based ion sieve by an ion exchange membrane, forming three different flow chambers. After energization, hydrogen ions are continuously generated by electrolysis at the cation electrode. + They continuously migrate into the ion exchange chamber, in a low H2O environment. +At certain concentrations, regeneration of the ion exchange sites in manganese-based ion sieves can significantly reduce manganese loss, decrease replacement costs, eliminate the need to shut down the manganese-based ion sieve equipment, and save substantial costs on manual maintenance.

[0052] (3) This invention monitors the Li in the anode chamber, cathode chamber, and ion exchange chamber in real time. + Concentration, Mn 4+ Concentration and conductivity were used to further confirm the progress of the ion exchange reaction, thereby determining the desorption sites so as to obtain the highest desorption amount with the lowest manganese loss.

[0053] (4) Since this invention does not use chemical acid reagents, there is no large amount of waste acid, waste solution, or cleaning wastewater discharged, thus it does not pollute water bodies, is harmless to the environment, and the manganese loss is negligible. It not only has great economic benefits but also very significant environmental benefits. At the same time, the method is simple to operate, convenient to use, and has low operating costs, which greatly reduces the regeneration cost of manganese ion sieves and simplifies the regeneration process. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the device structure shown in the present invention;

[0055] Figure 2 This is a schematic diagram of the device structure shown in Example 1;

[0056] Figure 3 The XRD characterization diagram of the manganese-based ion sieve shown in Example 1 is shown below.

[0057] Figure 4 The graph shows the adsorption-desorption cycle performance of the manganese-based ion sieve as shown in Example 1.

[0058] Explanation of markings in the diagram:

[0059] 1-Anode chamber, 11-Anode electrode, 12-First outlet, 13-First inlet, 14-First clamping plate;

[0060] 2-Cathode chamber, 21-Cathode electrode, 22-Second outlet, 23-Second inlet, 24-Second clamping plate;

[0061] 3-Ion exchange chamber, 31-Cation exchange membrane, 32-Anion exchange membrane, 33-Third outlet, 34-Third inlet;

[0062] 4-Power supply, 41-Positive terminal; 42-Negative terminal;

[0063] 5- Bolt. Detailed Implementation

[0064] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. In the following embodiments or examples, unless otherwise specified, the functional components or structures are conventional components or structures used in the art to achieve the corresponding functions.

[0065] It should be noted that in the description of this invention, the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0066] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0067] Unless otherwise specified, the reagents, methods, instruments and equipment used in this invention are conventional reagents, methods, instruments and equipment in the art.

[0068] In the following embodiments, the iridium-titanium electrode is a titanium-based coated nail; the titanium electrode is a titanium plate; the cation exchange membrane is model CGU-510*1460, purchased from Hangzhou Lanran Technology Co., Ltd.; the graphite electrode is model JL-11, purchased from Hefei Wenghe Metal Materials Co., Ltd.; the anion exchange membrane is model AM-2-510*1460, purchased from Hangzhou Lanran Technology Co., Ltd.

[0069] Li4Mn5O 12 Li 1.6 Mn 1.6 O4 and LiMn2O4 were prepared in the laboratory. The preparation process was as follows: Li4Mn5O 12 References [1], LiMn2O4 References [2].

[0070] Li 1.6 Mn 1.6O4 preparation process:

[0071] (1) Synthesis of intermediate LiMnO2: Weigh a certain mass of Mn2O3 and LiOH·H2O according to the stoichiometric ratio, grind and mix them evenly, and place them in a 50ml hydrothermal reactor. React at 120℃ for 48 hours. The lithium element in the crystal structure will be lost during the hydrothermal process and high-temperature calcination, so the LiOH·H2O in the raw material is in excess, and Li / Mn=1.1.

[0072] (2) Synthesis of ion sieve precursor Li 1.6 Mn 1.6 O4: The intermediate LiMnO2 powder obtained from the hydrothermal reaction was placed in an alumina crucible and sintered in a tube furnace at 400℃ for 24 hours, followed by natural cooling to room temperature to obtain Li. 1.6 Mn 1.6 O4 ion sieve precursor.

[0073] (3) Synthesis of manganese-based ion sieve H 1.6 Mn 1.6 O4: Then 0.5g of the prepared lithium-ion sieve precursor Li 1.6 Mn 1.6 O4 powder was soaked in 100 mL of 0.5 mol / L HCl for acidification for 24 h; the acidified solution was filtered, washed three times with deionized water, and then dried at 60 °C to obtain 0.5 g of the manganese-based ion sieve H. 1.6 Mn 1.6 O4

[0074] References:

[0075] [1]Xiao Jia-Li, Xiaoyao Nie, Sun Shu-Ying, et al. Lithium ion adsorption-desorption properties on spinel Li4Mn5O12 and pH-dependent ion-exchange model [J]. Advanced Powder Technology, 2015, 26: 589-594.

[0076] [2]K.Ooi,Y.Miyai,S.Katoh.Lithium-ion sieve property ofλ-typemanganese oxide[J].Solvent Extraction and Ion Exchange,1987,5(3):561-572.

[0077] Example 1

[0078] A device for regulating desorption sites to reduce manganese dissolution loss, such as... Figure 1 and 2 As shown, it includes:

[0079] The anode chamber 1 has a positive electrode 11, and its interior is filled with a low concentration of H2 that can be electrolyzed to generate H2. + An aqueous solution, wherein the anode 11 is connected to the positive electrode 41 of the power supply 4, generates a low concentration of H2O. + The concentration is 0.001–0.1 mol / L;

[0080] A cathode chamber 2 having a cathode electrode 21, wherein the cathode electrode 21 is connected to the negative terminal 42 of a power supply 4;

[0081] An ion exchange chamber 3 is disposed between the anode chamber 1 and the cathode chamber 2. The ion exchange chamber 3 is separated from the anode chamber 1 by a cation exchange membrane 31 and from the cathode chamber 2 by an anion exchange membrane 32. The ion exchange chamber 3 is used to fill the adsorbed manganese-based ion sieve. The anode chamber 1 contains H... + The manganese-based ion sieve is desorbed by entering the ion exchange chamber 3 through the cation exchange membrane 31.

[0082] When current is applied to the anode 11 and cathode 21, a direct current electric field is formed. After the current is applied, the aqueous solution in the anode chamber 1 is polarized, causing a small amount of water to ionize and release a sufficient amount of H+. + A reduction reaction of metal ions occurs in the cathode chamber 2. Under the action of an external electric field, H+ generated at the anode 11... + Selective migration occurs in a timely manner, passing through the cation exchange membrane 31 into the ion exchange chamber 3.

[0083] In this embodiment, the anode chamber 1 is filled with a 0.05 mol / L H₂SO₄ aqueous solution; the cathode chamber 2 is filled with a 3% CuCl₂ aqueous solution; and the ion exchange chamber 3 is filled with a 0.05 mol / L H₂SO₄ aqueous solution. Electrolyzed water can provide sufficient low concentrations of H₂. + This regulates desorption sites and reduces manganese loss during ion sieve desorption. Low-concentration H₂SO₄ aqueous solutions can further increase solution salinity, thus favoring the water electrolysis reaction.

[0084] In this embodiment, the power supply 4 is a DC power supply with a voltage of 3V; the manganese-based ion sieve is Li4Mn5O. 12The anode 11 is an iridium-titanium electrode, which is a titanium-based coated pin; the cathode 21 is a titanium electrode, which is a titanium plate; the cation exchange membrane 31 is of model CGU-510*1460, purchased from Hangzhou Lanran Technology Co., Ltd.; the anion exchange membrane 32 is of model AM-2-510*1460, purchased from Hangzhou Lanran Technology Co., Ltd.

[0085] In this embodiment, a first outlet 12 is provided on one side of the anode chamber 1, and a first inlet 13 is provided on the top. A first circulation pump is connected between the first outlet 12 and the first inlet 13 to realize the circulation of the aqueous solution in the anode chamber 1.

[0086] A second outlet 22 is provided on one side of the cathode chamber 2, and a second inlet 23 is provided on the top. A second circulation pump is connected between the second outlet 22 and the second inlet 23 to realize the circulation of the aqueous solution in the cathode chamber 2.

[0087] The ion exchange chamber 3 has a third outlet 33 on one side and a third inlet 34 on the top. A third circulation pump connects the third outlet 33 and the third inlet 34 to achieve the circulation of the aqueous solution within the ion exchange chamber 3. The circulation of the solution between the anode chamber 1, cathode chamber 2, and ion exchange chamber 3 improves the uniform distribution of the electrolyte and enhances the efficiency of the electrochemical process. By introducing the circulation pump, the flow rate and direction of the solution within the system can be controlled, optimizing electrolyte transfer and thus achieving more precise and efficient ion exchange in the electrochemical process.

[0088] In this embodiment, the anode chamber 1, cathode chamber 2, and ion exchange chamber 3 are used to detect Li. + Concentration, Mn 4+ Concentration and conductivity. Furthermore, the anode chamber, cathode chamber, and ion exchange chamber are subjected to frequent, repeated, and periodic sampling to detect Li. + Concentration, Mn 4 + The concentration and conductivity are used to determine the critical points of ion exchange desorption sites and redox desorption sites, thereby controlling the reaction to complete the desorption of the manganese-based ion sieve.

[0089] In this embodiment, a first clamping plate 14 is provided on the side of the anode 11 away from the anode chamber 1 to fix the anode 11; a second clamping plate 24 is provided on the side of the cathode 21 away from the cathode chamber 2 to fix the cathode 21; the first clamping plate 14, anode 11, anode chamber 1, cation exchange membrane 31, ion exchange chamber 3, anion exchange membrane 32, cathode 21, cathode chamber 2, and second clamping plate 24 are sequentially attached and fixedly connected by several bolts 5. The anode chamber 1 has a first cavity filled with the aqueous solution, the cathode chamber 2 has a second cavity filled with the salt solution, and the ion exchange chamber 3 has a third cavity filled with the aqueous solution; the bolts 5 are located around the periphery of the first cavity, second cavity, and third cavity. The top of the ion exchange chamber 3 is provided with several filling holes for filling the manganese-based ion sieve.

[0090] Using the above-described apparatus, desorption is performed on a manganese-based ion sieve adsorption solution with a lithium concentration of 170 ppm. The method includes the following steps:

[0091] A1. Fill the ion exchange chamber 3 with the adsorbed manganese ion sieve, add an aqueous solution to the anode chamber 1 and the ion exchange chamber 3, and add a salt solution to the cathode chamber 2.

[0092] A2. Turn on power supply 4 and adjust the voltage to generate 0.001–0.1 mol / L H₂ in the anode chamber 1. + H + It enters the ion exchange chamber 3 through the cation exchange membrane 31 and undergoes an ion exchange reaction with the manganese ion sieve to desorb metal ions;

[0093] A3. Periodically take water samples from the anode chamber 1, cathode chamber 2, and ion exchange chamber 3 to detect Li. + Concentration, Mn 4+ Concentration, pH, and conductivity are used to determine the critical points of ion exchange desorption sites and redox desorption sites, and the reaction is controlled to ensure that the manganese-based ion sieve completes desorption.

[0094] In this embodiment, in step A1, the amount of manganese-based ion sieve used is 10g;

[0095] In this embodiment, the anode chamber 1 is filled with a 0.05 mol / L H2SO4 aqueous solution; the cathode chamber 2 is filled with a 3% CuCl2 aqueous solution; and the ion exchange chamber 3 is filled with a 0.05 mol / L H2SO4 aqueous solution.

[0096] In this embodiment, in step A2, the power supply 4 is a DC power supply with a voltage of 3V;

[0097] The H generated in the anode chamber 1 + The concentration was consistently maintained between 0.001 and 0.05 mol / L.

[0098] In this embodiment, the anode chamber 1 is filled with a 0.05 mol / L H2SO4 aqueous solution; the cathode chamber 2 is filled with a 3% CuCl2 aqueous solution; and the ion exchange chamber 3 is filled with a 0.05 mol / L H2SO4 aqueous solution.

[0099] In this embodiment, the reaction mechanism of the ion exchange chamber 3 is as follows: Mn 4+ -RO-Li+H + =Mn 4+ -RO-H+Li + ;

[0100] The reaction mechanism of the anode chamber 1 is 2H₂O - 4e⁻ - =O2↑+4H + ;

[0101] The reaction mechanism of cathode chamber 2 is Cu 2+ +2e - =Cu.

[0102] In this embodiment, the anode chamber 1, cathode chamber 2, and ion exchange chamber 3 are subjected to frequent and repeated periodic sampling to detect Li. + Concentration, Mn 4+ Concentration, conductivity, and pH. Detection of Li + Concentration, Mn 4+ Concentrations were determined using an inductively coupled plasma optical emission spectrometer (ICP-OES; ARCOS FHS12), conductivity was determined using a DDS-307, and pH was determined using a PHSJ-3F.

[0103] I. Desorption Site Determination

[0104] Using the apparatus shown in Example 1, changes in lithium ion concentration, manganese ion concentration, conductivity, and pH in the three chambers were monitored in real time, and the results are shown in Tables 1 and 2. Each time, 1 ml of sample solution was taken from the three chambers and diluted to a 10 ml volumetric flask to measure the lithium ion and manganese ion concentrations. Changes in conductivity and pH were monitored in real time by inserting the probe into the aqueous solution.

[0105] The Li content of the sample was determined by ICP-OES, and the equilibrium adsorption capacity and the adsorption capacity at time t were further calculated, as shown in equations (1-1) and (1-2).

[0106] Q e =(C0-C e V / m (1-1)

[0107] Q t =(C0-C t V / m (1-2)

[0108] In the formula, Q e Q represents the equilibrium adsorption capacity of the lithium-ion sieve, in mg / g. t Ct represents the adsorption capacity of the lithium-ion sieve at time t, in mg / g; C0 represents the Li0 in the solution. + Initial concentration, mg / L; C e To achieve adsorption equilibrium, Li + Concentration, mg / L; C t Let Li be at time t + The concentration of is mg / L; V is the solution volume, L; m is the mass of the ion sieve, g.

[0109] The Li and Mn contents of the samples were determined by ICP-OES, and the manganese dissolution rate and lithium extraction rate were further calculated as shown in equation (1-3).

[0110] R M =(C e ×V)W M (1-3)

[0111] In the formula, R M For lithium ion sieves, the Li removal rate (M = Li) or manganese dissolution rate (M = Mn) is used; C e V is the concentration of Li or Mn in the acid-treated aqueous solution, in mg / L; V is the solution volume, in L; W M denoted as the mass of Li and Mn in the adsorbent, in mg.

[0112] Table 1 Performance Test Results of Manganese Ion Screen Electroregeneration Process

[0113]

[0114] Table 2. Conductivity and pH values ​​during the electroregeneration process of manganese-based ion sieves.

[0115]

[0116] Table 1 shows that the amount of lithium ions desorbed in the ion exchange chamber increases with increasing desorption time, reaching 8.31 mg / g at the tenth minute, while manganese dissolution rate is undetectable. The increase in lithium ion desorption is significant in the first four minutes, reaching 15.36 mg / g at the fortieth minute, with a negligible manganese dissolution rate of only 0.007%, indicating an ion exchange reaction occurring in the manganese-based ion sieve. In the subsequent sixtieth minute, the increase in desorption is not significant, but the increase in manganese dissolution rate is more pronounced (>0.02%), indicating a redox reaction. The detection of lithium ions in the anode chamber with increasing desorption time is due to the concentration gradient causing a small portion of lithium ions to migrate from the ion exchange chamber to the anode chamber. The changes in total desorption and manganese dissolution follow the same pattern as those in the ion exchange chamber.

[0117] Table 2 shows that the pH value of the ion exchange chamber continuously decreases with increasing desorption time, indicating that lithium ions in the adsorbent material and hydrogen ions in the solution are constantly exchanging lithium ions and hydrogen ions. The pH values ​​of the cathode and anode chambers remain basically unchanged. The increase in conductivity in all three chambers indicates that a large number of lithium ions are desorbed into the solution in a short period of time, and that the anode chamber continuously provides hydrogen ions through water electrolysis.

[0118] Therefore, when the ion exchange time is between 0 and 60 minutes (excluding 60 minutes), the manganese-based ion sieve is at the critical point between the ion exchange desorption site and the redox desorption site. At this time, the manganese dissolution rate of the manganese-based ion sieve is less than 0.02%, and the adsorption amount is greater than 12 mg / g. At this time, the manganese dissolution rate is very small and can be almost ignored. If the reaction time is increased further, the manganese dissolution rate increases rapidly, while the increase in lithium ion desorption amount is not obvious.

[0119] II. Cyclic Performance Testing

[0120] The manganese-based ion sieve shown in Example 1 was subjected to an adsorption-desorption cycle. The adsorption solution used was the same as that shown in Example 1, with a lithium concentration of 170 ppm. The desorption process used the apparatus shown in Example 1 with the same parameters, and the ion exchange reaction time for desorption was 30 min. After each desorption, residual regeneration solution and regeneration products (obtained by H+) were removed from ion exchange chamber 3. + Ion-exchanged Li + Use deionized water to clean until the pH of the effluent reaches neutral.

[0121] The desorption rate and manganese loss after 15 cycles of adsorption-desorption using a manganese-based ion sieve are as follows: Figure 3 As shown, the lithium desorption rate of the lithium ion sieve remained at 98%, without significant decrease, and the manganese dissolution rate was only 0.02%. Figure 4 The image shows the XRD pattern of the manganese-based ion sieve after 15 adsorption-desorption cycles, indicating that the cycling experiment did not change the spinel structure and that the cycling stability was good.

[0122] Example 2

[0123] Compared to Example 1, most aspects are the same, except that the anode chamber 1 is filled with a 0.05 mol / L NaCl aqueous solution; the cathode chamber 2 is filled with a 3% FeCl2 aqueous solution; and the ion exchange chamber is filled with Li. 1.6 Mn 1.6 O4, the ion exchange chamber 3 is filled with deionized water. The electrolyzed water provides a sufficient low concentration of H2. + It regulates desorption sites and reduces manganese dissolution during the ion sieve desorption process.

[0124] In this embodiment, the power supply 4 is a DC power supply with a voltage of 10V; the manganese-based ion sieve is Li. 1.6 Mn 1.6 O4; the anode 11 is a graphite electrode; the cathode 21 is a graphite electrode, which is a graphite plate. The manganese dissolution rate is 0.01%, and the desorption amount is 16 mg / g.

[0125] Example 3

[0126] Compared to Example 1, most aspects are the same, except that the anode chamber 1 is filled with a 0.05 mol / L NaCl aqueous solution; the cathode chamber 2 is filled with a 5% CuCl2 aqueous solution; the ion exchange chamber is filled with LiMn2O4; and the ion exchange chamber 3 is filled with deionized water. The electrolyzed water provides sufficient low concentrations of H+. + This method regulates desorption sites and reduces manganese loss during ion sieve desorption. Low-concentration acidic aqueous solutions can further increase solution salinity, thus favoring the water electrolysis reaction. The manganese loss rate was 0.02%, and the desorption amount was 13.31 mg / g.

[0127] In this embodiment, the power supply 4 is a DC power supply with a voltage of 1V; the manganese ion sieve is LiMn2O4; the anode 11 is a graphite electrode; and the cathode 21 is a graphite electrode, which is a graphite plate.

[0128] Example 4

[0129] Compared to Example 1, most aspects are the same, except that the anode chamber 1 is filled with a 0.05 mol / L Na₂SO₄ aqueous solution; the cathode chamber 2 is filled with a 0.05 mol / L Na₂SO₄ aqueous solution; the ion exchange chamber is filled with LiMn₂O₄; and the ion exchange chamber 3 is filled with deionized water. The electrolyzed water provides sufficient low concentrations of H₂. + It regulates desorption sites and reduces manganese dissolution during the ion sieve desorption process.

[0130] Example 5

[0131] Most of them are the same as in Example 1, except that the power supply 4 is a DC power supply with its voltage adjusted to 0.1V.

[0132] Example 6

[0133] Compared with Example 1, most of them are the same, except that the power supply 4 is a DC power supply with its voltage adjusted to 1V.

[0134] Example 7

[0135] Compared with Example 1, most of them are the same, except that the power supply 4 is a DC power supply with its voltage adjusted to 10V.

[0136] Example 8

[0137] Compared with Example 1, most of them are the same, except that the power supply 4 is a DC power supply with its voltage adjusted to 15V.

[0138] Example 9

[0139] Compared with Example 1, most of them are the same, except that the power supply 4 is a DC power supply with its voltage adjusted to 20V.

[0140] Comparative Example 1:

[0141] Desorption was performed using conventional chemical acid washing methods at the same acid concentration. 10 g of Li₄Mn₅O₃, the same weight as in Example 1, was added to an Erlenmeyer flask. 12 Add the same volume (130 ml) of 0.05 mol / L acid of the same concentration. React at 25°C and 300 rpm for 60 min on a shaker. Dilute 1 ml of the sample solution to a 10 ml volumetric flask and measure its lithium and manganese ion concentrations. When the desorption amount of lithium during chemical regeneration was 9 mg / g, the manganese dissolution rate was 0.6%, significantly higher than the manganese dissolution rate in Example 1. This indicates that the control system, through electrolysis of water using a DC electric field to generate a dilute acid regeneration solution, can achieve regeneration of low-concentration hydrogen ions without causing manganese dissolution, improving the recognition ability of desorption sites. Under the influence of the electric field, ions diffuse to varying degrees, significantly affecting the lithium separation process.

[0142] Comparative Example 2

[0143] The process for Comparative Example 2 was largely the same as that for Example 2, except that the constant voltage was replaced with a constant current of 10 mA. Manganese dissolution rate and lithium ion desorption were tested under the same conditions. The manganese dissolution rate was 0.02%, and the desorption amount was 11.96 mg / g, indicating a higher manganese dissolution rate and a lower adsorption amount compared to Example 2.

[0144] Comparative Example 3:

[0145] Compared to Example 2, desorption was performed using a conventional chemical acid washing method at the same acid concentration, with the same weight of Li as in Example 1 added to the conical flask. 1.6 Mn 1.6 O4 was added, along with the same volume and concentration of acid. When the lithium desorption amount during chemical regeneration was 12 mg / g, the manganese loss rate was 0.4%, significantly higher than that in Example 2. This indicates that the control system, through electrolysis of water using a DC electric field to generate a dilute acid regeneration solution, can achieve regeneration of low-concentration hydrogen ions without causing manganese loss, thus improving the recognition ability of desorption sites. Under the influence of the electric field, ions diffuse to varying degrees, significantly impacting the lithium separation process.

[0146] Comparative Example 4

[0147] The process for Comparative Example 3 was largely the same as that for Example 3, except that the solution in the anode chamber was replaced with 0.5M NaCl. Manganese dissolution rate and lithium ion desorption were tested under the same conditions. The manganese dissolution rate was 0.03%, and the desorption amount was 11.23 mg / g.

[0148] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for desorption using a manganese-based ion sieve, characterized in that, The apparatus used in this method includes: An anode chamber (1) with a positive electrode (11) is filled with a low-concentration H2O that can be electrolyzed to generate H2O. + An aqueous solution, wherein the anode (11) is connected to the positive electrode (41) of the power supply (4), generates a low concentration of H2O. + The concentration is 0.001~0.1 mol / L; A cathode chamber (2) having a cathode electrode (21) connected to the negative terminal (42) of a power supply (4). An ion exchange chamber (3) is disposed between the anode chamber (1) and the cathode chamber (2). The ion exchange chamber (3) is separated from the anode chamber (1) by a cation exchange membrane (31), and the ion exchange chamber (3) is separated from the cathode chamber (2) by an anion exchange membrane (32). The ion exchange chamber (3) is used to fill the adsorbed manganese-based ion sieve. The anode chamber (1) contains H + The manganese-based ion sieve is desorbed by entering the ion exchange chamber (3) through the cation exchange membrane (31); The method includes the following steps: A1. Fill the ion exchange chamber (3) with the adsorbed manganese ion sieve, add an aqueous solution to the anode chamber (1) and the ion exchange chamber (3), and add a salt solution to the cathode chamber (2); A2. Turn on the power supply (4) and adjust the voltage to generate 0.001~0.1 mol / L H in the anode chamber (1). + H + It enters the ion exchange chamber (3) through the cation exchange membrane (31) and undergoes an ion exchange reaction with the manganese ion sieve to desorb the metal ions; A3. Periodically take water samples from the anode chamber (1), cathode chamber (2), and ion exchange chamber (3) to detect Li. + Concentration, Mn 4+ Concentration, pH, and conductivity are used to determine the critical points of ion exchange desorption sites and redox desorption sites, and the reaction is controlled to ensure that the manganese-based ion sieve completes desorption. The power supply (4) is a DC power supply with a voltage of 0.1~20V; The H generated in the anode chamber (1) + The concentration was consistently maintained at 0.001~0.05 mol / L.

2. The method for desorption using a manganese-based ion sieve according to claim 1, characterized in that, The aqueous solution filled inside the anode chamber (1) includes deionized water, 0~0.05mol / L H2SO4 aqueous solution, 0~0.1mol / L HCl aqueous solution, 0.01~5mol / L Na2SO4, and 0.01~5mol / L NaCl; The cathode chamber (2) contains a salt solution, including one or more of the following: 1-5% CuCl2 aqueous solution, 0.01-5 mol / L Na2SO4, 0.01-5 mol / L NaCl, NaOH solution, or oxidant solution; The oxidant solution includes Fe... 3+ Cu 2+ I2, Cr 3+ Cd 2+ Pb 2+ PO4 3- V 3+ HCOOH, HCHO, SbO + VO 2+ H2MoO4, MnO4 - Ti 3+ Ag + A solution containing at least one ion; The ion exchange chamber (3) is filled with an aqueous solution, including deionized water, 0~0.05mol / L H2SO4 aqueous solution, 0~0.1mol / L HCl aqueous solution, 0.01-5mol / L Na2SO4 or 0.01-5mol / L NaCl.

3. The method for desorption using a manganese-based ion sieve according to claim 1, characterized in that, The power supply (4) is a DC power supply with a voltage of 0.1~20V; The manganese-based ion sieve includes LiMn2O4 and Li4Mn5O4. 12 Li 1.6 Mn 1.6 O4 or Li 1.33 Mn 1.67 O4.

4. The method for desorption using a manganese-based ion sieve according to claim 1, characterized in that, The anode (11) includes at least one of titanium electrode, iridium titanium electrode, carbon electrode, platinum electrode, stainless steel electrode, copper electrode, silver electrode, aluminum electrode, and metal alloy electrode; The cathode (21) includes at least one of the following: titanium electrode, iridium titanium electrode, carbon electrode, platinum electrode, stainless steel electrode, copper electrode, silver electrode, aluminum electrode, and metal alloy electrode; The cation exchange membrane (31) includes a common cation exchange membrane, a monovalent cation exchange membrane, and a divalent cation exchange membrane; The anion exchange membrane (32) includes a common anion exchange membrane, a monovalent anion exchange membrane, and a divalent anion exchange membrane.

5. The method for desorption using a manganese-based ion sieve according to claim 1, characterized in that, The anode chamber (1) is provided with a first outlet (12) on one side and a first inlet (13) on the top. A first circulation pump is connected between the first outlet (12) and the first inlet (13) to realize the circulation of the aqueous solution in the anode chamber (1). A second outlet (22) is provided on one side of the cathode chamber (2), and a second inlet (23) is provided on the top. A second circulation pump is connected between the second outlet (22) and the second inlet (23) to realize the circulation of the aqueous solution in the cathode chamber (2). The ion exchange chamber (3) has a third outlet (33) on one side and a third inlet (34) on the top. A third circulation pump is connected between the third outlet (33) and the third inlet (34) to realize the circulation of the aqueous solution in the ion exchange chamber (3).

6. The method for desorption using a manganese-based ion sieve according to claim 1, characterized in that, A first clamp (14) is provided on the side of the anode electrode (11) away from the anode chamber (1) to fix the anode electrode (11). A second clamp (24) is provided on the side of the cathode electrode (21) away from the cathode chamber (2) to fix the cathode electrode (21). The first clamping plate (14), the anode (11), the anode chamber (1), the cation exchange membrane (31), the ion exchange chamber (3), the anion exchange membrane (32), the cathode (21), the cathode chamber (2), and the second clamping plate (24) are attached in sequence and fixedly connected by several bolts (5).

7. The method for desorption using a manganese-based ion sieve according to claim 1, characterized in that, In step A1, the mass-to-volume ratio of the manganese-based ion sieve to the aqueous solution in the ion exchange chamber (3) is 0.015-0.24 g / ml; The aqueous solution filled inside the anode chamber (1) includes deionized water, 0~0.05mol / L H2SO4 aqueous solution, 0~0.1mol / L HCl aqueous solution, 0.01~5mol / L Na2SO4, and 0.01~5mol / L NaCl; The cathode chamber (2) contains a salt solution, including one or more of the following: 1-5% CuCl2 aqueous solution, 0.01-5 mol / L Na2SO4, 0.01-5 mol / L NaCl, NaOH solution, or oxidant solution; The oxidant solution includes Fe... 3+ Cu 2+ I2, Cr 3+ Cd 2+ Pb 2+ PO4 3- V 3+ HCOOH, HCHO, SbO + VO 2+ H2MoO4, MnO4 - Ti 3+ Ag + A solution containing at least one ion; The ion exchange chamber (3) is filled with an aqueous solution, including deionized water, 0~0.05mol / L H2SO4 aqueous solution, 0~0.1mol / L HCl aqueous solution, 0.01-5mol / L Na2SO4 or 0.01-5mol / L NaCl.

8. The method for desorption using a manganese-based ion sieve according to claim 1, characterized in that, In step A3, the interval between taking water samples from the anode chamber (1), cathode chamber (2) and ion exchange chamber (3) is 10 min to 60 min. The critical point for ion exchange desorption sites and redox desorption sites is that the manganese dissolution rate of the manganese-based ion sieve is less than 0.02% and the adsorption capacity is greater than 12 mg / g. The reaction time is 10-60 min.

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