Dual selection electro-controlled ion permeation-exchange membrane system and method for simultaneous separation of anions and cations thereof

Abstract

The application discloses a double-selection electrically-controlled ion permeation-exchange membrane system and a method for synchronously separating anions and cations, and belongs to the technical field of ion exchange membrane. The double-selection electrically-controlled ion permeation-exchange membrane system comprises a constant-voltage power supply, a pulse power supply and a membrane stack with three membranes and three chambers as a repeating unit, which is composed of a double-selection electrically-controlled ion permeation-exchange membrane and a bipolar membrane. The double-selection electrically-controlled ion permeation-exchange membrane is prepared by combining a lithium-based double-metal hydroxide electrically-active membrane with double selection for bromine and lithium ions and an anion and cation exchange membrane. The chamber of the membrane stack is an alternating circulation structure of a double-selection electrically-controlled ion permeation-exchange cation membrane ESIPM+CM, a bipolar membrane BPM and a double-selection electrically-controlled ion permeation-exchange anion membrane ESIPM+AM. The application is a combination of the double-selection electrically-controlled ion permeation-exchange membrane and the bipolar membrane technology, is a multifunctional combined technology for recovering lithium and bromine resources in a salt lake and generating lithium hydroxide and hydrogen bromide products with high added value, realizes multi-level products and multifunctionality of the device, and can effectively reduce operation cost.

Description

Technical Field

[0001] This invention relates to a dual-selective electro-controlled ion permeation-exchange membrane system and a method for simultaneously separating anions and cations. Specifically, it relates to the preparation of a dual-selective electro-controlled ion permeation-exchange membrane and the continuous electro-controlled separation and recovery of high-value lithium and bromine resources in salt lake brine, and the conversion of these resources into lithium hydroxide and hydrogen bromide products using bipolar membrane technology; it belongs to the field of salt lake resource recovery and separation technology. Background Technology

[0002] Salt lake brines contain abundant inorganic salt resources, including considerable reserves of some high-value rare elements such as lithium, rubidium, cesium, bromine, and iodine. Therefore, how to efficiently separate high-value ions from salt lake brines has become a key issue in the field of salt lake resource utilization.

[0003] Lithium is an important resource, with salt lake lithium resources accounting for approximately 85% of my country's total reserves. Its products are widely used in the battery industry, lubricating grease, and nuclear industry. With the rapid development of new energy vehicles, ternary high-nickel battery materials have become mainstream, significantly increasing the demand for lithium hydroxide, a basic lithium salt product. Furthermore, bromine, as a high-value-added halogen element, is an essential basic chemical raw material, widely used in flame retardants, bactericides, rubber, pharmaceutical intermediates, and mercury adsorbents. Therefore, the continuous and efficient extraction of lithium and bromide ions from brine and their conversion into corresponding products has promising application prospects.

[0004] The main separation technologies for target ions in salt lake brine include ion exchange, adsorption, and membrane separation. Traditional ion separation technologies often suffer from drawbacks such as cumbersome operation, limited selectivity, low adsorption / desorption efficiency, and the need for acid and alkali addition during regeneration, which can easily lead to secondary pollution.

[0005] In recent years, electro-controlled ion selective osmosis (ESIP) has attracted much attention as an environmentally friendly ion separation technology. It achieves rapid insertion and removal of low-concentration target ions by adjusting the oxidation / reduction potential of electroactive functional membrane materials, without generating secondary pollution. Chinese patent CN 106621816A discloses a method for continuous recovery of lead ions via electro-controlled ion selective osmosis, mainly targeting lead ion separation. This method selectively permeates only cations, without considering the simultaneous separation of anions and cations or the efficient utilization of resources. Furthermore, Chinese patent CN 112939295A discloses a method for preparing acids and alkalis via sodium sulfate bipolar membrane electrodialysis, cleverly combining bipolar membranes with anion and cation exchange membranes to form a bipolar membrane electrodialysis process, solving the problems of complexity and high cost in existing acid and alkali production processes. However, due to the limited selectivity of ions during electrodialysis, the quality of the imported water is particularly important; therefore, the pretreatment process for acid and alkali production via bipolar membrane electrodialysis is relatively cumbersome. Chinese patent CN113774234A discloses a device and process for producing acid and alkali using a bipolar membrane-electro-controlled ion membrane extraction method. This method employs electro-controlled ion extraction technology and bipolar membrane technology to achieve selective permeation of anions and cations. However, the preparation processes for the anion and cation permeation membranes differ, and the OH groups generated by the bipolar membrane cannot be guaranteed. - and H + Entering the raw material chamber causes raw material contamination and membrane contamination (such as the formation of precipitates like magnesium hydroxide).

[0006] While electro-controlled ion-selective osmosis membranes and bipolar membrane acid and alkali production technologies have been studied, methods for selective directional ion separation using dual-selective electro-controlled ion-osmosis-exchange membranes have not yet been reported. Furthermore, methods for achieving simultaneous separation of anions and cations and acid and alkali production using only a single membrane have also not been reported. Summary of the Invention

[0007] The present invention aims to provide a dual-selective electro-controlled ion permeation-exchange membrane system and a method for simultaneously separating anions and cations, with the objective of constructing a dual-selective electro-controlled ion permeation-exchange membrane system for the continuous, directional, and simultaneous separation of bromine and lithium anions and cations.

[0008] First, a dual-selective electrically controlled ion-permeation membrane is prepared using a lithium-based LDH electroactive material exhibiting dual selectivity for bromine and lithium anions and cations. This membrane is then coupled with an anion-cation exchange membrane to prepare a dual-selective electrically controlled ion-permeation-exchange membrane. Furthermore, leveraging the hydrolysis properties of the bipolar membrane, it is combined with the dual-selective electrically controlled ion-permeation-exchange membrane to form a dual-selective electrically controlled ion-permeation-exchange membrane system. This invention utilizes an applied electric field and pulsed voltage as driving forces, significantly improving ion adsorption and desorption efficiency, and the presence of the anion-cation exchange membrane avoids H+ ionization. + OH -The transmembrane migration of ions, and the generation of corresponding acid and base products using bipolar membranes, is a clean production process with continuous operation, high ion selectivity, and high separation efficiency, and has broad application prospects.

[0009] This invention provides a dual-selective electro-controlled ion permeation-exchange membrane system, which consists of a membrane stack with a "three-membrane, three-chamber" repeating unit, comprising a constant voltage power supply, a pulse power supply, a dual-selective electro-controlled ion permeation-exchange membrane, and a bipolar membrane. The dual-selective electro-controlled ion permeation-exchange membrane is prepared by combining a dual-selective electro-controlled ion permeation (ESIPM, lithium-based bimetallic hydroxide electroactive membrane) with dual selectivity for bromine and lithium ions with an anion and cation exchange membrane. The chambers of the membrane stack are an alternating circulating structure of dual-selective electro-controlled ion permeation-exchange cation membrane (ESIPM+CM) - bipolar membrane (BPM) - dual-selective electro-controlled ion permeation-exchange anion membrane (ESIPM+AM). Feed solution is transported between the chambers composed of ESIPM+AM and ESIPM+CM, lithium hydroxide is recovered in the chamber composed of ESIPM+CM and BPM, and bromic acid is recovered in the chamber composed of BPM and ESIPM+AM.

[0010] This invention prepares a dual-selective electrically controlled ion-permeation-exchange membrane by combining a dual-selective electrically controlled ion-permeation membrane (ESIPM) with an anion and cation exchange membrane, comprising a dual-selective electrically controlled ion-permeation-exchange cation membrane (ESIPM+CM) and a dual-selective electrically controlled ion-permeation-exchange anion membrane (ESIPM+AM).

[0011] This invention provides a method for assembling the above-mentioned dual-selection electrically controlled ion permeation-exchange membrane system, comprising the following steps: The dual-selective electro-controlled ion-permeation-exchange membrane consists of an electro-controlled ion-selective permeation membrane (ESIPM) with dual-selective electroactivity and an anion-cation exchange membrane with anion-cation exchange capacity; An electroactive dual-selective electro-controlled ion permeation membrane (ESIPM) is prepared by dissolving and mixing lithium-based LDH, a conductive enhancer, and a binder, and then preparing the membrane by one of the following methods: filtration, extrusion, coating, or spraying. The mass ratio of the active material, the conductive enhancer, and the binder is 8:1:1. Furthermore, lithium-based LDHs include lithium-Al-LDHs, Li-Al-Fe-LDHs, and other lithium-based metal hydroxides; conductive enhancers include one or more of conductive carbon black, graphene, and carbon nanotubes; and binders include one or more of polytetrafluoroethylene, polyvinyl alcohol, polyacrylic acid, chitosan, and cellulose.

[0012] (2) Anion and cation exchange membranes are coupled on ESIPM by one of the following methods: surface grafting, polymerization, or bonding, and finally a dual-selective electro-controlled ion permeation-exchange membrane is obtained, including a dual-selective electro-controlled ion permeation-exchange cation membrane (ESIPM+CM) and a dual-selective electro-controlled ion permeation-exchange anion membrane (ESIPM+AM). (3) A bipolar membrane is installed between ESIPM+AM and ESIPM+CM to form a membrane stack, and a dual-selection electrically controlled ion permeation-exchange membrane system is formed with a constant voltage power supply and a pulse power supply.

[0013] The anion and cation exchange membranes are AMI-7001S anion exchange membranes and CMI-7000S cation exchange membranes.

[0014] The bipolar membrane is a commercially available bipolar membrane, including one of the following: German FuMA-Tech Fumasep FBM-PK bipolar membrane, Japanese ASTOM bipolar membrane, and Jierui Environmental Protection bipolar membrane.

[0015] Mechanism of the invention: The dual-selective electro-ion permeation-exchange membrane has dual selectivity for lithium and bromide ions. The membrane is used to elute lithium ions on lithium-based LDH with aqueous solution. Lithium ions first pass through the cation exchange membrane and then through the lithium ion vacancies on the lithium-based LDH plates for electro-ion selective permeation. Bromide ions first pass through the anion exchange membrane and then through the interlayer anion exchange of the lithium-based LDH for electro-ion selective permeation.

[0016] This invention provides a method for simultaneously separating anions and cations in the aforementioned dual-selective electro-controlled ion permeation-exchange membrane system. Under the action of an external electric field, ① a negative potential pulse voltage is applied to the ESIPM of the ESIPM+CM membrane, causing lithium ions to migrate directionally to the ESIPM+AM membrane and then to the lattice vacancies within the ESIPM. Reversing the pulse voltage allows the lithium ions to pass through the ESIPM+CM to reach the alkaline chamber, where they react with OH- generated by the bipolar membrane. - ② A positive potential pulse voltage is applied to the ESIPM of the ESIPM+AM membrane. Bromine ions migrate directionally to the ESIPM+AM membrane and then migrate directionally between the layers within the ESIPM. Reversing the pulse voltage allows the bromide ions to pass through the ESIPM+AM membrane to reach the acid chamber, where they react with H+ generated by the bipolar membrane. + The HBr product is formed.

[0017] This invention provides a method for simultaneously separating anions and cations in the aforementioned dual-selective electro-controlled ion permeation-exchange membrane system, comprising the following steps: selectively and directionally transferring lithium and bromide ions by applying a pulsed voltage to the dual-selective electro-controlled ion permeation membrane portion and coupling it with a cell voltage; simultaneously, the bipolar membrane generates H under the influence of an electric field. + and OH -This ultimately achieves the recovery of acids and alkalis. The specific method is as follows: (1) Inject the receiving liquid (water or low-concentration hydrogen bromide and lithium hydroxide solution, 0 ~ 50 ppm) and the raw material liquid (salt lake brine) into the chamber. After the flow rates of each water flow in the device reach equilibrium and stability, turn on the pulse power supply. The dual-selection electrically controlled ion-osmosis-exchange membrane system can be used in brine solutions with a total salinity below 100 g / L, where Li + Concentrations above 10 ppm, Br - The concentration is above 1 ppm.

[0018] (2) A constant cell voltage (5 ~ 20 V) is applied to the outermost electrode. A negative pulse voltage is applied to the ESIPM of the dual-selective electro-ion permeation-exchange cation membrane (ESIPM+CM), and a positive pulse voltage is applied to the ESIPM of the dual-selective electro-ion permeation-exchange anion membrane (ESIPM+AM). Lithium and bromide ions in the feed solution migrate directionally to the dual-selective electro-ion permeation-exchange membrane. Lithium ions migrate and permeate through the lattice vacancies of ESIPM+CM, and bromide ions migrate and permeate through the interlayer of ESIPM+AM. The separation of lithium ions and bromide ions is achieved through the selectivity of the dual-selective electro-ion permeation-exchange membrane. (3) Under the coupling effect of pulse voltage and cell voltage, lithium ions and bromide ions pass through the dual-selective electrically controlled ion permeation-exchange membrane and the OH- generated by the bipolar membrane. - and H + The corresponding acid and alkali products are produced.

[0019] In the above separation method, under the action of an external electric field, positive and negative potentials are alternately applied to the membrane electrode through a circuit control system to achieve the synchronous insertion and removal of target bromine and lithium ions. Combined with a liquid circuit control system, selective and continuous electro-controlled separation of target bromine and lithium ions can be achieved. Simultaneously, bipolar membrane technology is used to convert them into corresponding acid and base products. Furthermore, the dual-selective electro-controlled ion permeation-exchange membrane can also limit the H2 produced by the bipolar membrane. + OH - The contaminated raw material chamber is used to achieve directional migration within the chamber.

[0020] In the above separation method, the pulse voltage range on the dual-selective electro-controlled ion permeation-exchange membrane is -5 V to 5 V, the pulse width is 20 s to 2000 s, and the voltage range of the applied electric field is 5 V to 20 V.

[0021] In the above separation methods, the dual-selective electrically controlled ion permeation-exchange membrane can limit the H2 produced by the bipolar membrane. + and OH -The material reaches the feed chamber through a dual-selection electro-ion permeation-exchange membrane, preventing contamination of the feed chamber. The anion and cation exchange membranes on the dual-selection electro-ion permeation-exchange membrane only allow anions or cations to pass through, realizing that the dual-selection electro-ion permeation-exchange cation membrane (ESIPM+CM) only allows cations to pass through and the dual-selection electro-ion permeation-exchange anion membrane (ESIPM+AM) only allows anions to pass through, preventing anions and cations from passing through a single membrane at the same time.

[0022] The beneficial effects of this invention are: (1) This invention is a combination of dual-selection electro-controlled ion permeation-exchange membrane and bipolar membrane technology. It is a multi-functional combined technology for recovering lithium and bromine resources in salt lakes and generating high-value-added lithium hydroxide and hydrogen bromide products. It realizes multi-stage product processing and the multi-functionality of the device, and can effectively reduce operating costs. (2) A dual-selective electrically controlled ion permeation-exchange membrane was prepared using lithium-based LDH, which achieved bidirectional selectivity of lithium and bromide ions. At the same time, it combined with anion and cation exchange membranes to achieve directional migration of ions. The dual-selective electrically controlled ion permeation-exchange membrane can be reused. (3) Using pulse voltage as the main driving force avoids secondary pollution caused by chemical reagent regeneration, and greatly improves the ion transfer efficiency and extraction rate; (4) It can operate continuously and can achieve simultaneous separation of lithium and bromide ions, which is beneficial for industrial production. Attached Figure Description

[0023] Figure 1 This is a diagram of the apparatus for the simultaneous separation of anions and cations using a dual-selective electro-controlled ion permeation-exchange membrane according to the present invention.

[0024] Figure 2 This is a schematic diagram of the operation of the dual-selection electrically controlled ion permeation-exchange membrane system of the present invention (applying a negative pulse voltage).

[0025] Figure 3 This is a schematic diagram of the operation (applying a positive pulse voltage) of the dual-selection electrically controlled ion permeation-exchange membrane system of the present invention. Detailed Implementation

[0026] The specific embodiments of the present invention will be further described below, but are not limited to the following embodiments: like Figure 1As shown, this invention provides a device for the simultaneous separation of lithium and bromide ions using a dual-selective electrically controlled ion-exchange membrane. The device has a multi-chamber structure and consists of a membrane stack, a constant voltage power supply, and a pulse power supply. It employs an alternating circulation structure of a dual-selective electrically controlled ion-exchange cation membrane (ESIPM+CM), a bipolar membrane (BPM), and a dual-selective electrically controlled ion-exchange anion membrane (ESIPM+AM). The feed solution is introduced into the chamber formed by ESIPM+AM and ESIPM+CM; the receiving solution (water or low-concentration lithium hydroxide, 0-50 ppm) is introduced into the chamber formed by ESIPM+CM and BPM; and the receiving solution (water or low-concentration hydrogen bromide, 0-50 ppm) is introduced into the chamber formed by BPM and ESIPM-AM. Selective directional separation of lithium and bromide ions is achieved by applying a pulsed voltage (±0.5 V to ±1.0 V) to the dual-selective electrically controlled ion-exchange membrane.

[0027] The application of the present invention will be further illustrated below through specific embodiments.

[0028] Example 1: Using Figure 1 The dual-selective electrically controlled ion-osmosis-exchange membrane system shown separates lithium and bromide ions. The dual-selective electrically controlled ion-osmosis membrane is prepared by dissolving a mixture of Li-Al-LDH, conductive carbon black, and polytetrafluoroethylene (PTFE) in a mass ratio of 8:1:1, and then coating the mixture into a membrane. Subsequently, an ion exchange membrane (USA AMI-7001S anion exchange membrane and CMI-7000S cation exchange membrane) is assembled onto the surface of the dual-selective electrically controlled ion-osmosis membrane using interfacial polymerization to form the dual-selective electrically controlled ion-osmosis-exchange membrane system. This system is then combined with a commercial bipolar membrane (Germany FuMA-Tech Fumasep FBM-PK bipolar membrane) to form the dual-selective electrically controlled ion-osmosis-exchange membrane system. 500 mL of brine from a salt lake was introduced into the feed chamber, while 500 mL of 10 ppm lithium hydroxide and 500 mL of 10 ppm hydrogen bromide were introduced into the receiving solution. The solution in each compartment circulated within the membrane stack at a flow rate of 250 mL / min. The cell voltage was controlled at 10 V using a DC power supply. Alternating pulse potentials of -1 V to 1 V were applied to the dual-selective electrically controlled ion-permeation-exchange membrane using a pulse power supply, with a pulse width of 120 s. The Mg in the brine... 2+ The concentration is 15000 ppm, Li + The concentration is 500 ppm, Br - The concentration is 200 ppm, Cl - The concentration was 23,300 ppm. After working for 60 minutes, Li + Penetration rate reaches 95%, Br - Permeability reaches 94%, Mg 2+ C1 -The rejection rate is >99%. Mg 2+ C1 - The rejection rate was >99%. The extraction rate of lithium hydroxide and hydrogen bromide solutions was 0.6 L / h, with concentrations of 2.38 g / L and 7.53 g / L, respectively.

[0029] Example 2: Using Figure 1 The dual-selective electro-controlled ion-osmosis-exchange membrane system shown performs cation and anion separation. The dual-selective electro-controlled ion-osmosis-exchange membrane is prepared by dissolving a mixture of Li-Al-Fe-LDH, carbon nanotubes, and polytetrafluoroethylene (mass ratio 8:1:1) and then filtering the resulting membrane. This membrane is then combined with anion and cation exchange membranes (AMI-7001S anion exchange membrane and CMI-7000S cation exchange membrane from the USA) via surface polymerization to form the dual-selective electro-controlled ion-osmosis-exchange membrane. This is then combined with a commercial bipolar membrane (ASTOM bipolar membrane from Japan) to form the dual-selective electro-controlled ion-osmosis-exchange membrane system. The feed solution is 500 mL of brine from a salt lake, and the receiving solution is 500 mL of pure water. The solution in each compartment circulates in the membrane stack at a flow rate of 250 mL / min. A DC power supply controls the tank voltage to 10 V, and a pulsed power supply alternately applies a -0.8 V to 0.8 V pulse potential to the dual-selective electro-controlled ion-osmosis-exchange membrane, with a pulse width of 240 s. The Mg in the brine... 2+ The concentration is 10000 ppm, Li + The concentration is 600 ppm, Br - The concentration was 220 ppm, Cl - The concentration was 25,000 ppm. After working for 60 minutes, its Li + Penetration rate reached 93%, Br - Permeability reaches 93%, Mg 2+ C1 - The rejection rate was >99%. The extraction rate of lithium hydroxide and hydrogen bromide solutions was 1 L / h, with concentrations of 1.44 g / L and 4.86 g / L, respectively.

[0030] The efficiency of the dual-selection electro-controlled ion permeation-exchange membrane remains at 99% after 20 cycles of operation.

[0031] Example 3: Using Figure 1The dual-selective electro-controlled ion-osmosis-exchange membrane system shown separates lithium and bromide ions. The dual-selective electro-controlled ion-osmosis membrane is prepared by dissolving a mixture of Li-Al-LDH, conductive carbon black, and polytetrafluoroethylene (PTFE) (mass ratio 8:1:1), and then spraying this mixture onto the surface of ion exchange membranes (USA AMI-7001S anion exchange membrane and CMI-7000S cation exchange membrane). This mixture is then combined with a commercial bipolar membrane (Germany FuMA-Tech FumasepFBM-PK bipolar membrane) to form the dual-selective electro-controlled ion-osmosis-exchange membrane system. The feed solution is 5 L of brine from a salt lake, and the receiving solution is 5 L of pure water. The circulation flow rate of the solution in each compartment within the membrane stack is 2.5 L / min. A DC power supply controls the tank voltage to 20 V, and a pulsed power supply alternately applies a -0.8 V to 0.8 V pulse potential to the dual-selective electro-controlled ion-osmosis-exchange membrane, with a pulse width of 180 s. The Mg in the brine... 2+ The concentration was 14000 ppm, Li + The concentration was 540 ppm, Br - The concentration is 200 ppm, Cl - The concentration was 25,000 ppm. After working for 60 minutes, its Li + Penetration rate reached 93%, Br - Permeability reaches 92%, Mg 2+ C1 - The rejection rate was >96%. The extraction rate of lithium hydroxide and hydrogen bromide solutions was 5 L / h, with concentrations of 1.34 g / L and 4.56 g / L, respectively.

[0032] Example 4: Using Figure 1 The dual-selective electro-controlled ion-permeation-exchange membrane system shown separates lithium and bromide ions. The dual-selective electro-controlled ion-permeation membrane is prepared by dissolving a mixture of Li-Al-LDH, conductive carbon black, and polytetrafluoroethylene (PTFE) (mass ratio 8:1:1), and then spraying this mixture onto the surface of ion exchange membranes (USA AMI-7001S anion exchange membrane and CMI-7000S cation exchange membrane). This mixture is then combined with a commercial bipolar membrane (Germany FuMA-Tech FumasepFBM-PK bipolar membrane) to form the dual-selective electro-controlled ion-permeation-exchange membrane system. 50 L of brine from a salt lake is introduced into the feed chamber, while 50 L of 10 ppm lithium hydroxide and 50 L of 10 ppm hydrogen bromide are introduced into the receiving solution. The circulation flow rate of the solution in each compartment within the membrane stack is 25 L / min. The tank voltage is controlled at 20 V using a DC power supply, and alternating pulse potentials of -1 V to 1 V are applied to the dual-selective electro-controlled ion-permeation-exchange membrane using a pulse power supply, with a pulse width of 120 s. Mg in the salt lake brine 2+ The concentration is 15000 ppm, Li+ The concentration was 480 ppm, Br - The concentration was 205 ppm, Cl - The concentration was 23,000 ppm. After working for 60 minutes, Li + Penetration rate reached 92%, Br - Permeability reaches 93%, Mg 2+ C1 - The rejection rate is >99%. Mg 2+ C1 - The rejection rate was >96%. The extraction rate of lithium hydroxide and hydrogen bromide solutions was 100 L / h, with concentrations of 2.34 g / L and 7.48 g / L, respectively.

[0033] The efficiency of the aforementioned dual-selection electro-controlled ion permeation-exchange membrane remained at 92% after 7 days of operation.

Claims

1. A dual-selection electrically controlled ion permeation-exchange membrane system, characterized in that: The membrane stack consists of a constant voltage power supply, a pulse power supply, a dual-selection electrically controlled ion permeation-exchange membrane, and a bipolar membrane, with a three-membrane, three-chamber repeating unit. The dual-selective electro-controlled ion permeation-exchange membrane has dual selectivity for bromine and lithium ions; the dual-selective electro-controlled ion permeation-exchange membrane is prepared by combining a lithium-based bimetallic hydroxide electroactive membrane ESIPM with dual selectivity for bromine and lithium ions with anion and cation exchange membranes, including a dual-selective electro-controlled ion permeation-exchange cation membrane ESIPM+CM and a dual-selective electro-controlled ion permeation-exchange anion membrane ESIPM+AM. The membrane stack has an alternating circulation structure of dual-selective electrically controlled ion-osmosis-exchange cation membrane ESIPM+CM, bipolar membrane BPM, and dual-selective electrically controlled ion-osmosis-exchange anion membrane ESIPM+AM. The chambers composed of ESIPM+AM and ESIPM+CM are used for feed liquid transportation, the alkaline chamber composed of ESIPM+CM and BPM is used for lithium hydroxide recovery, and the acid chamber composed of BPM and ESIPM+AM is used for bromic acid recovery.

2. A method for assembling the dual-selective electrically controlled ion permeation-exchange membrane system according to claim 1, characterized in that... Includes the following steps: (1) The dual-selective electro-controlled ion permeation-exchange membrane is composed of an electro-controlled ion-selective permeation membrane ESIPM with dual-selective electroactivity and an anion-cation exchange membrane with anion-cation exchange performance; The electroactive dual-selective electro-controlled ion permeation membrane ESIPM is prepared by dissolving and mixing lithium-based LDH, a conductivity enhancer and a binder, and then preparing the membrane by one of the following methods: filtration, extrusion, coating or spraying. (2) Anion and cation exchange membranes are coupled on ESIPM by one of the following methods: surface grafting, polymerization, or bonding, and finally a dual-selective electro-controlled ion permeation-exchange membrane is obtained: including dual-selective electro-controlled ion permeation-exchange cation membrane ESIPM+CM and dual-selective electro-controlled ion permeation-exchange anion membrane ESIPM+AM. (3) A bipolar membrane is installed between ESIPM+AM and ESIPM+CM to form a membrane stack, and a dual-selection electrically controlled ion permeation-exchange membrane system is formed with a constant voltage power supply and a pulse power supply.

3. The assembly method of the dual-selection electrically controlled ion permeation-exchange membrane system according to claim 2, characterized in that: In step (1), the mass ratio of lithium-based LDH: conductive reinforcing agent: binder is 8:1:1; lithium-based LDH is a metal hydroxide with lithium as the metal source, including Li-Al-LDH and Li-Al-Fe-LDH; conductive reinforcing agent includes one or more of conductive carbon black, graphene, and carbon nanotubes; binder includes one or more of polytetrafluoroethylene, polyvinyl alcohol, polyacrylic acid, chitosan, and cellulose.

4. The assembly method of the dual-selection electrically controlled ion permeation-exchange membrane system according to claim 2, characterized in that: The anion and cation exchange membranes are AMI-7001S anion exchange membranes and CMI-7000S cation exchange membranes. The bipolar membranes are commercially available bipolar membranes, including one of the following: German FuMA-Tech Fumasep FBM-PK bipolar membrane, Japanese ASTOM bipolar membrane, and Jierui Environmental Protection bipolar membrane.

5. A method for simultaneously separating anions and cations using a dual-selective electro-controlled ion permeation-exchange membrane system as described in claim 1, characterized in that: Selective and directional transport of lithium and bromide ions is achieved by applying a pulsed voltage to the dual-selective electro-ion permeation-exchange membrane section of the dual-selective electro-ion permeation-exchange membrane system and coupling it with the cell voltage; simultaneously, H+ is generated in the bipolar membrane under the influence of the electric field. + and OH - Ultimately, this achieves the recovery of acids and alkalis.

6. The method for simultaneous separation of anions and cations in a dual-selective electro-controlled ion permeation-exchange membrane system according to claim 5, characterized in that... The specific method is as follows: Under the influence of an external electric field, ① a negative potential pulse voltage is applied to the ESIPM of ESIPM+CM, causing lithium ions to migrate directionally to the ESIPM+AM film and then to the lattice vacancies within the ESIPM. Reversing the pulse voltage allows lithium ions to pass through ESIPM+CM and reach the alkali chamber, where they react with OH- generated by the bipolar membrane. - ① Formation of LiOH product; ② Applying a positive potential pulse voltage to the ESIPM of ESIPM+AM, bromide ions migrate directionally to the ESIPM+AM membrane and then migrate directionally between the layers within the ESIPM. Reversing the pulse voltage, bromide ions pass through ESIPM+AM to reach the acid chamber, where they react with H+ generated by the bipolar membrane. + The HBr product is formed.

7. The method for simultaneous separation of anions and cations in a dual-selective electro-controlled ion permeation-exchange membrane system according to claim 6, characterized in that... Includes the following steps: (1) Inject the receiving liquid and the raw material liquid into the chamber. After the flow rates of each water flow in the device reach equilibrium and stability, turn on the pulse power supply. The receiving liquid is water or a low-concentration solution of hydrogen bromide and lithium hydroxide, 0 ~ 50 ppm; the feed liquid is brine from a salt lake. (2) A constant cell voltage is applied to the outermost electrode, a negative pulse voltage is applied to the ESIPM of the dual-selection electro-ion permeation-exchange cation membrane, and a positive pulse voltage is applied to the ESIPM of the dual-selection electro-ion permeation-exchange anion membrane. Lithium and bromide ions in the feed solution migrate directionally to the dual-selection electro-ion permeation-exchange membrane. Lithium ions migrate and permeate through the lattice vacancies of ESIPM+CM, and bromide ions migrate and permeate through the interlayer of ESIPM+AM. Lithium ions and bromide ions are separated by the selectivity of a dual-selective electro-controlled ion permeation-exchange membrane; (3) Under the coupling effect of pulse voltage and cell voltage, lithium ions and bromide ions pass through the dual-selective electrically controlled ion permeation-exchange membrane and the OH- generated by the bipolar membrane. - and H + The corresponding acid and base products are generated.

8. The method for simultaneous separation of anions and cations in a dual-selective electro-controlled ion permeation-exchange membrane system according to claim 7, characterized in that: The pulse voltage range on the dual-selection electro-controlled ion permeation-exchange membrane is -5 V to 5 V, the pulse width is 20 s to 2000 s, the voltage range of the applied electric field is 5 V to 20 V, and the cell voltage is 5 V to 20 V.

9. The method for simultaneous separation of anions and cations in a dual-selective electro-controlled ion permeation-exchange membrane system according to claim 5, characterized in that: A dual-selection electrically controlled ion-osmosis-exchange membrane system is used for brine solutions with a total salinity below 100 g / L, wherein Li + Concentrations above 10 ppm, Br - The concentration is above 1 ppm.

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