653 results about "Electrodialysis" patented technology

The invention relates to the technical field of coal bed gas development and gas extraction, in particular to an electrodialysis-liquid CO2 time sequence synergistic anti-reflection method and system. Comprising an electrodialysis pretreatment stage, a CO2 synergetic permeability increasing stage and a process regulation and energy recovery stage, a mixed solution is injected into a coal seam in a pulse injection mode, and energy recovery is conducted through pipeline fluid pressure in the injection stopping period. According to the technical scheme, through multi-stage cooperation of electrodialysis pretreatment, CO2 phase change fracturing and pulse consolidation and regulation, accurate transformation of the coal seam low-permeability area is achieved. According to the scheme, electrodialysis is utilized to drive an acidic working solution to target and migrate to a difficult-to-permeate area, mineral substances are dissolved, and pores are expanded; then, high-energy expansion stress is generated through liquid CO2 phase change, and a through fracture network is formed; and finally, a pulse injection and energy recovery mechanism is adopted, fracture closing is restrained, system energy consumption is reduced, and therefore the coal seam breathability and the gas extraction efficiency are integrally improved.

The invention relates to a novel composite bipolar membrane for preparing low-carbon alcohol alkali metal salt and an electrodialysis process of the novel composite bipolar membrane, and belongs to the technical field of membrane separation and electrochemical synthesis. The composite bipolar membrane comprises a cation exchange layer, a middle catalyst layer and an anion exchange layer which are sequentially laminated and compounded, the process comprises the following steps: introducing a salt solution containing alkali metal ions into an anode chamber of a bipolar membrane electrodialysis system, and introducing a low-carbon alcohol solution into a cathode chamber; applying a direct-current electric field to the two sides of the composite bipolar membrane, so that the low-carbon alcohol is dissociated at the membrane interface to generate alkoxy ions and hydrogen ions; the alkoxy ions migrate to an anode chamber to be combined with the alkali metal ions to generate low-carbon alcohol alkali metal salt; the membrane material is high in adaptability, the membrane structure is good in stability, technological parameters are mature, and the system integration degree is high.

The application discloses a bipolar membrane electrodialysis device, which comprises an outer box body and further comprises a liquid inlet mechanism, a plurality of electrodialysis mechanisms and a plurality of filtering mechanisms. The filtering mechanism comprises a filtering box, a driving filtering assembly and a liquid feeding assembly. The driving filtering assembly comprises a motor installed on the top of the filtering box, the output shaft of the motor is fixedly connected with a threaded rod, the outer periphery of the threaded rod is threadedly connected with a filtering plate slidingly connected to the inner wall of the filtering box, and the bottom inner wall of the filtering box is fixedly connected with a plurality of plug rods matched with filtering holes of the filtering plate. Raw water is delivered to the inside of the filtering box through the liquid inlet mechanism, is actively filtered without turbulence through the driving filtering assembly, is delivered to the corresponding electrodialysis mechanism through the liquid feeding assembly and is further subjected to electrodialysis treatment. The filtering plate and other components are arranged to filter out the solid impurities mixed in industrial glucose acid salt, so that the bipolar membrane electrodialysis process and the bipolar membrane body are not affected.

The invention relates to a method for simultaneously preparing lithium hydroxide and sulfuric acid. The invention provides a method for simultaneously preparing lithium hydroxide and sulfuric acid, which comprises the following steps: preparing a bipolar membrane electrodialysis device which comprises a first bipolar membrane, an anion exchange membrane, a cation exchange membrane and a second bipolar membrane, and forming an acid chamber between the first bipolar membrane and the anion exchange membrane, a salt chamber is formed between the anion exchange membrane and the cation exchange membrane, and an alkali chamber is formed between the cation exchange membrane and the second bipolar membrane; a lithium sulfate aqueous solution is added into a salt chamber of the bipolar membrane electrodialysis device, a sulfuric acid aqueous solution is added into an acid chamber, and a lithium hydroxide aqueous solution is added into an alkali chamber; and discharging the desalted solution formed in the salt chamber of the bipolar membrane electrodialysis device, discharging the sulfuric acid aqueous solution formed in the acid chamber, and discharging the lithium hydroxide aqueous solution formed in the alkali chamber.

The invention relates to the technical field of electrochemical water treatment, and discloses a high-salt waste liquid electric flocculation hardness removal and electrodialysis resourceful treatment method and a high-salt waste liquid electric flocculation hardness removal and electrodialysis resourceful treatment system. The method comprises the following steps: collecting water quality parameters of the high-salt waste liquid and initial electrochemical impedance spectroscopy parameters of a polar plate; calculating the initial current density according to the hardness and the conductivity, carrying out electric flocculation treatment, monitoring impedance spectrum change in real time, identifying the scaling type, and predicting the residual operation time of the polar plate; the current density is optimized according to the prediction time, and the residual hardness is calculated; and adjusting electrodialysis parameters by taking the residual hardness as a feedforward signal for concentration, and performing bipolar membrane electrodialysis on the concentrated solution to obtain acid-alkali liquor. The problems that in the electrochemical treatment process of the high-salt waste liquid, the state of a polar plate cannot be monitored in real time, consequently, operation parameters are adjusted blindly, and energy consumption is high and the recycling efficiency is low due to the fact that parameters of a pretreatment unit and parameters of a pretreatment unit are not linked are solved.

Provided is a cation exchange membrane in which when a hydroxide aqueous solution showing strong alkalinity is produced by using an electrodialyzer, significant swelling in the cation exchange membrane in contact with the hydroxide aqueous solution is suppressed, destruction of a cation exchange resin due to polyvalent cations contained as impurities in a raw material inorganic salt is suppressed, and the capacity of the cation exchange membrane is hardly lowered.　This cation exchange membrane is characterized by having an electric resistance of 2.0-5.0 (Ω∙cm2), as measured at 25ºC in 0.5 mol / L of a NaCl aqueous solution, and a dimensional change rate of at most 1.2%.

The invention belongs to the technical field of impurity separation, and particularly discloses a method for separating and purifying impurities in a process for preparing glyoxylic acid through oxalic acid electrolysis, a crystallization kettle is included, an isolation device is arranged in the crystallization kettle, and the isolation device comprises a conical top cover, a conveying pipe, an annular filter screen, a directional conveying assembly and a sealing assembly; the conical top cover is arranged at the axis of the crystallization kettle, an opening of the conical top cover faces downwards, and a plurality of fixing rods are fixedly connected between the top of the conical top cover and the inner wall of the side face of the crystallization kettle. According to the method, glyoxylic acid product solutions with different concentration specifications and the high-purity glyoxylic acid crystal can be obtained after the electrolyte is sequentially subjected to pre-evaporation, electrodialysis, secondary evaporation, cooling crystallization, solid-liquid separation, washing and drying and other procedures, so that the prepared high-purity glyoxylic acid crystal can be popularized and applied in the field of high-end medicine.

The invention discloses a waste sulfuric acid treatment method and device, the device comprises a sintered filter element filter, a fine filtration coalescer, an adsorption tank and a membrane separator which are connected in sequence, and the fine filtration coalescer adopts a ceramic membrane tube or a polytetrafluoroethylene membrane tube or a silicon carbide lining membrane tube as a filter material; an adsorption material in the adsorption tank is one or a combined adsorption material of more than two of activated carbon, a modified molecular sieve, a metal organic framework material and a nano adsorption material; and the membrane separation system adopts one or a combined membrane of more than two of an ultrafiltration membrane, a reverse osmosis membrane and an electrodialysis membrane. The alkylation waste acid regeneration process can be simplified, the occupied area of the device is saved, the engineering investment is reduced, and the operation cost is greatly reduced compared with that of an existing process technology; according to the method, a physical separation means is adopted, organic polymeric oil, dissolved organic matters, dissolved salts and other impurities in the alkylated waste sulfuric acid can be effectively removed without decomposing and reconstructing the waste sulfuric acid, and the concentrated sulfuric acid after concentration completely meets the production requirements of an alkylation device.

The invention provides a method for recovering nitrogen and phosphorus in wastewater through self-driven bipolar membrane electrodialysis. A system used in the method takes a magnesium negative electrode as a positive electrode and an air electrode as a positive electrode, and a self-driven primary battery is formed through wire connection; and ion exchange membranes with specific sequences are sequentially arranged between the two electrodes to form eight chambers, namely an anode chamber, a nitrogen and phosphorus recovery chamber, a wastewater chamber, a metal ion chamber, an ammonia water chamber, a hydrochloric acid chamber, a buffer chamber and a cathode chamber. During operation, an external power supply is not needed, and ion migration is driven by a self-generated electric field: after Mg < 2 + > and PO4 < 3-> are enriched in the nitrogen and phosphorus recovery chamber and NH4 < + > and Ca < 2 + > migrate to the metal ion chamber, NH4 < + > enters the ammonia water chamber through the monovalent cation exchange membrane, and Ca < 2 + > is separated out and reacts with OH <-> generated by the bipolar membrane to generate Ca (OH) 2 precipitate, so that membrane blockage is effectively prevented, and finally, NH4 < + >, Mg < 2 + > and PO4 < 3-> react to generate high-purity struvite. Zero energy consumption of nitrogen and phosphorus recovery of the wastewater is achieved, no additional chemicals exist, anti-blocking operation is achieved, and both environmental benefits and resource benefits are achieved.

The present invention relates to the field of cationic polymers, and in particular, to highly alkali-stable poly(arylene alkylene piperidinium) cationic polymers and preparation methods and applications. The preparation method for the highly alkali-stable poly(arylene alkylene piperidinium) cationic polymers includes the following steps: performing catalytic polycondensation on 1-R6-piperidine-3-carboxaldehyde or a salt or hydrate thereof and an aromatic compound to obtain a polymer having a piperidine moiety; and then further subjecting the polymer to a quaternization reaction to obtain the poly(arylene alkylene piperidinium) cationic polymer. The anion exchange membranes prepared from the piperidinium-based cationic polymers have ultra-high alkaline stability and excellent mechanical properties and ionic conductivities, and can be applied to the fields of electrochemical energy conversion such as fuel cells, hydrogen production by water electrolysis, electrochemical reduction of carbon dioxide, flow batteries, and fields of separation such as electrodialysis and water treatment.

The invention discloses a fluorescence scanning coupled electrodialysis optimized electro-Fenton wastewater treatment combined device, and relates to the field of wastewater treatment, the fluorescence scanning coupled electrodialysis optimized electro-Fenton wastewater treatment combined device comprises a pretreatment system, an analysis system and a treatment system, the fluorescence scanning module is used for carrying out fluorescence scanning on the wastewater in the pretreatment tank and transmitting data to the humification index calculation module, so that proper Cl <-> concentration is accurately analyzed. The electrodialysis Cl <-> removal device scientifically regulates and controls the concentration of Cl <-> in the wastewater according to the feedback of the Cl <-> concentration sensor and the result of the calculation module, creates conditions for the efficient and safe operation of the Fe < 2 + > / HClO electro-Fenton reaction device, and promotes the effective treatment of the Fe < 2 + > / HClO electro-Fenton reaction device on organic matters. And meanwhile, the device realizes that the salt is firstly utilized and then removed, so that the resource waste is avoided. Finally, full-index up-to-standard discharge of the high-salt organic wastewater is realized at low cost, the wastewater treatment efficiency and quality are improved, the treatment cost is reduced, and the method has important significance on environmental protection and sustainable utilization of resources.

According to the offshore green hydrogen methanol production system and method based on waste heat coupling electrodialysis to achieve fresh water self-supply, in the system, a PEM electrolytic hydrogen production subsystem electrolyzes fresh water through renewable energy source electric power to produce high-pressure hydrogen and oxygen, and process waste heat is generated; the methanol synthesis subsystem is connected with the PEM electrolytic hydrogen production subsystem, so that hydrogen and carbon dioxide are synthesized into crude methanol under the action of a catalyst, the crude methanol is rectified and purified into a green methanol product, and meanwhile, reaction waste heat is generated; the multi-stage electrodialysis seawater desalination subsystem is connected with the PEM electrolytic hydrogen production subsystem, seawater is subjected to multi-stage electrodialysis desalination treatment by the multi-stage electrodialysis seawater desalination subsystem to generate fresh water, and the fresh water is buffered by a fresh water storage tank and then is fed back to the PEM electrolytic hydrogen production subsystem to form a fresh water self-sustaining closed loop; and the heat recovery cooling water circulation loop respectively exchanges heat with the PEM electrolytic hydrogen production subsystem and the methanol synthesis subsystem so as to recover waste heat.

The invention discloses a liquid guide hole structure and an electrodialysis partition plate assembly and an electrodialysis device thereof, and belongs to the technical field of electrodialysis, the liquid guide hole structure comprises a water retaining assembly, and the water retaining assembly is used for being arranged in a liquid guide hole; the water retaining assembly comprises water retaining plates which are arranged in parallel at intervals, and a gap is formed between the top of each water retaining plate and the inner wall of the corresponding liquid guide hole; a baffle runner is formed between every two adjacent water baffles, and the baffle runners communicate with the partition plate runners. The water retaining assembly is arranged in the liquid guide hole, so that the baffle flow channel is formed in the liquid guide hole, the baffle flow channel forces thin liquid or concentrated liquid flowing out of the partition plate flow channel to be gathered with liquid flowing out of other partition plate flow channels after passing through a longer flow path and a smaller cross section area, the resistance of a leakage current circuit is remarkably increased, and the leakage current circuit is more stable. Therefore, the leakage current is effectively reduced.

This invention discloses a multi-stage treatment method for photovoltaic fluoride-containing wastewater based on semi-permeable membrane separation and the semi-permeable membrane thereof. The multi-stage treatment method includes the following steps: S1, primary treatment; S2, secondary treatment; S3, tertiary treatment. This method first performs primary treatment on the initially high-impurity fluoride-containing wastewater, which can rapidly degrade organic matter and heavy metals in the wastewater. Then, secondary treatment removes most of the heavy metal ions from the wastewater. Crystallization can effectively remove dissolved salts from the wastewater, while electrodialysis can concentrate and recover metal ions from low-concentration wastewater and desalinate the wastewater. Finally, tertiary treatment efficiently separates fluoride ions from the wastewater, and reverse osmosis filtration further removes the remaining fluoride ions and other dissolved salts, ensuring effluent quality. The semi-permeable membrane is a modified polyethersulfone membrane, and water quality is further purified by adding microorganisms.

The invention discloses a green process method for extracting alkali metal from composite ore, and relates to the field of metal extraction.The green process method comprises the following steps that S1, aluminosilicate composite ore containing alkali metal and ammonium carbonate are mixed and roasted, and activated clinker is obtained; s2, mixing the activated clinker with an ammonium citrate solution, carrying out a leaching reaction at 80-95 DEG C, and carrying out solid-liquid separation after the reaction to obtain a leaching solution and leaching residues; according to the green process method for extracting the alkali metal from the composite ore, through systematic coupling of a low-temperature ammonium carbonate activation-ammonium citrate complexing leaching-manganese system / ammonium phosphomolybdate specific adsorption-bipolar membrane electrodialysis closed-loop regeneration technology chain, a synergistic interaction effect is formed; the activation step significantly improves the leaching efficiency of the subsequent mild leaching agent.

The invention provides an electrodialysis and heat pump combined energy tower organic salt solution treatment system and method. The electrodialysis and heat pump combined energy tower organic salt solution treatment system comprises a heat pump system and an electrodialysis system, the heat pump system comprises a refrigerant loop, a solution loop, a circulating air loop and a freezing dehumidification loop; the refrigerant loop comprises a compressor, a first heat exchanger, a second heat exchanger, a throttling valve and an evaporator which are sequentially connected through a conveying pipeline to form a loop. The solution loop comprises a solution boiling regenerator, an energy tower, a first solution circulating secondary water pump, a second solution circulating secondary water pump, a hot solution circulating pump and a second heat exchanger which are sequentially connected through a conveying pipeline to form a loop, and the first heat exchanger directly sinks in the solution boiling regenerator. The problem that the solution concentration capacity of electrodialysis is reduced in a low-temperature environment is solved by utilizing the heat pump, so that in the low-temperature environment, an organic salt solution of an energy tower can be continuously concentrated to meet the anti-freezing salinity requirement after absorbing heat in air and feeding water to dilute the solution concentration.

This invention relates to the field of hydrometallurgical technology and discloses a method for purifying and recovering ammonium perrylate using a combination of electrodialysis and ion exchange. The method first adjusts the pH of the rhenium-containing feed solution, then selectively enriches perrylate ions using electrodialysis to obtain a high-concentration rhenium-rich solution. Subsequently, the rhenium-rich solution is subjected to deep adsorption purification through an anion exchange column. Next, rhenium is eluted from the saturated resin using an eluent to obtain a pure ammonium perrylate solution. Finally, high-purity ammonium perrylate crystals are obtained through evaporation, concentration, cooling, crystallization, and drying. Optionally, the obtained crystals can be recrystallized to further improve purity. This invention ensures the purity and process stability of the rhenium-rich solution obtained in the pre-enrichment stage, improves the overall adsorption capacity, desorption rate, and reliability of the process operation of the resin, and guarantees the stability of the final ammonium perrylate product purity and the economic benefits of the entire process recovery.

A method for producing an inclusion complex drug includes the following steps: adding cyclodextrin to an aqueous solution of ibuprofen sodium salt at a saturation concentration at a first temperature, then placing it in an electrodialysis apparatus to obtain a first crystallization solution; then removing it and adding acid to adjust the pH to 6.0-6.5, controlling the temperature at a second temperature to obtain a second crystallization solution; placing the second crystallization solution in an electrodialysis apparatus to obtain a third crystallization solution; then removing it and continuing to add acid to adjust the pH to below 3.0 to obtain a fourth crystallization solution; filtering and recovering the fourth crystallization solution, and rinsing to obtain the ibuprofen inclusion complex. This application uses pre-added cyclodextrin, with cyclodextrin and the ibuprofen sodium salt obtained from the reaction as feedstock, then obtaining the second crystallization solution through electrodialysis acidification and acid treatment, followed by electrodialysis to obtain raw materials that can be used as nucleation sites for crystallization, and finally adding acid for final crystallization. The entire crystallization process is controllable.

This invention provides a side-chain quinine polymer, its preparation method, and its application in the preparation of anion exchange membranes, belonging to the fields of fuel cells and water electrolysis for hydrogen production. First, an aromatic monomer, a functional monomer, and a quinine monomer are synthesized into a quinine polymer with good alkali resistance via a superacid-catalyzed condensation reaction. Second, a side-chain quinine polymer is prepared based on the synthesized quinine polymer. Finally, the side-chain quinine polymer is used as the main chain polymer for casting, and a high-performance all-carbon chain anion exchange membrane is obtained through side-chain grafting modification. The alkaline anion exchange membrane prepared by this invention exhibits excellent chemical stability, ionic conductivity, and mechanical properties, demonstrating superior overall performance. It can be applied in alkaline fuel cells, water electrolysis, energy storage batteries, carbon dioxide conversion, electrodialysis, and other electrochemical device fields.

This utility model discloses an electrodialysis industrial wastewater treatment device, including a wastewater treatment tank. Two concave plates are installed inside the wastewater treatment tank, and rectangular frames are slidably connected within the concave plates. Ion exchange membranes are installed within the rectangular frames, and the two ion exchange membranes divide the wastewater treatment tank into a freshwater chamber and two concentrated water chambers, with the two concentrated water chambers located on either side of the freshwater chamber. Holding the positioning plate and moving it upwards causes the connecting rod to move upwards. When the connecting rod moves upwards, it causes the surrounding plate, filter screen, and partition plate to move upwards, compressing the second spring in the partition plate. Then, releasing the positioning plate causes the second spring to rebound, causing the connecting rod, surrounding plate, and filter screen to move downwards. This causes the surrounding plate to impact the baffle, generating vibration. The vibration of the surrounding plate causes the filter screen to vibrate. Since the surrounding plate and filter screen are horizontally arranged, the vibration facilitates the discharge of impurities from the filter screen. Repeatedly pulling the positioning plate upwards and then releasing it further improves the discharge of impurities from the filter screen.

The design is characterized by its shape. The design is a liquid dispenser that is connected to at least one of the upper and lower parts of a frame that forms a reaction chamber in which a reaction between substances occurs in an electrochemical device, such as an electrodialysis tank, thereby enabling the uniform distribution and supply of liquid through the frame. The dashed lines indicate parts of the article that do not form part of the design sought to be registered. 1.1) Perspective view; 1.2) Front view; 1.3) Rear view; 1.4) Left side view; 1.5) Right side view; 1.6) Top view; 1.7) Bottom view.

The application relates to the technical field of bipolar membrane electrodialysis, and provides a bipolar membrane, a preparation method, an activation method and application thereof. The bipolar membrane provided by the application has obviously improved service life and is not prone to bubble and delamination phenomena during long-time operation. The preparation method comprises the following steps: forming an adhesive layer between the cation exchange layer and the catalyst layer, and / or forming an adhesive layer between the anion exchange layer and the catalyst layer. Preferably, the cation exchange layer is provided with sulfonic acid groups, and the anion exchange layer is provided with quaternary ammonium groups.

The application discloses a method and integrated system for enriching lithium and removing boron from salt lake brine, and belongs to the technical field of lithium resource purification. The method comprises the following steps: S1. primary electrodialysis of the salt lake brine to obtain a primary low-boron lithium concentrate and a primary boron-rich dilute solution; S2. reverse osmosis of the primary boron-rich dilute solution to obtain a reverse osmosis concentrate; S3. nanofiltration of the reverse osmosis concentrate to remove boron and obtain a nanofiltration lithium concentrate; S4. mixing of the nanofiltration lithium concentrate and hydrochloric acid and then secondary electrodialysis to obtain a secondary low-boron lithium concentrate; the secondary low-boron lithium concentrate is returned to step S1 and mixed with the salt lake brine; and the water inlet of the primary electrodialysis and the secondary electrodialysis is controlled to have a pH of 7-12. The method provided by the application effectively improves the enrichment and purification efficiency of lithium and the removal efficiency of boron, and is simple and easy to implement. The application further provides an integrated system for implementing the above method.

The application discloses a kind of salt ion exchange membrane for electrodialysis and preparation method thereof, cation exchange membrane is immersed in the buffer containing tannic acid and zwitterion diamine monomer, reaction is carried out at 0~60 ℃ for 0.5~60 h, obtain salt ion exchange membrane for electrodialysis.The application is formed by the Michael addition or Schiff base reaction between tannic acid molecule and zwitterion diamine monomer under weak alkaline condition, uniform, stable tannic acid / diamine zwitterion ultrathin coating is formed on the surface of cation exchange membrane.The application significantly improves Li + / Mg 2+ Selectivity. Preparation process is simple, environmental protection, strong universality, the modified cation exchange membrane prepared by the application has excellent Li + / Mg 2+ Selectivity, and can improve the anti-pollution of membrane, can be used for high magnesium lithium ratio brine electrodialysis method lithium extraction.

The electrodialysis device includes a plurality of gaskets stacked in one direction, each of which allows a different solution to pass therethrough, a plurality of ion exchange membranes positioned between the gaskets, and a liquid supply frame positioned on one side of the gaskets and supplying the different solutions to each of the gaskets, the liquid supply frame including a central module overlapping the gaskets in the one direction, and an upper module coupled to an upper portion of the central module, communicating with the gaskets, and including a plurality of discharge flow paths through which the different solutions that have passed through the gaskets are discharged.

Methods of separating water, salt, CO2, and crude oil from wastewater, the methods comprising: providing gas / oil separation system that produces a waste saline water stream and a CO2 stream; providing an electrochemical cell having an anode, a cathode, and three electrodialytic compartments; feeding a fresh water stream to the anode to produce H+ and O2; feeding the waste CO2 stream and O2 to the cathode to produce bicarbonate (HCO3—) and hydroxide ions (OH−); feeding the waste saline water stream to a center electrodialytic compartment; wherein the sodium Na+ from the waste saline water stream reacts with the bicarbonate to form NaHCO3 and the chloride (Cl−) from the waste saline water stream reacts with the H+ to produce hydrochloric acid; and producing salt and desalinated water.

The application provides a multi-stage reverse electrodialysis device system and a power generation method thereof, which utilizes the salt difference energy of concentrated seawater. The device system comprises a concentrated seawater tank, n-stage river water tanks, n-stage electrolyte tanks and n-stage reverse electrodialysis membrane stacks connected in series, and n is greater than or equal to 2. The concentrated seawater tank is connected to the first-stage reverse electrodialysis membrane stack. The i-stage river water tank and the i-stage electrolyte tank are independently connected to the i-stage reverse electrodialysis membrane stack, and 1 is less than or equal to i and is less than or equal to n. The power generation method comprises the following steps: (1) introducing the concentrated seawater, the river water and the electrolyte into the concentrated seawater tank, the n-stage river water tanks and the n-stage electrolyte tanks respectively; (2) setting the flow rates of the concentrated seawater, the river water and the electrolyte, and starting the n-stage reverse electrodialysis membrane stacks to generate power. The device system provided by the application effectively utilizes the salt difference energy and reduces the salinity of the concentrated seawater, realizes the standard discharge of the concentrated seawater, meets the green and environmental protection resource utilization requirements and is conducive to large-scale popularization and application.

This invention discloses a method and system for selective separation of monovalent and divalent ions in an alginate fiber coagulation bath based on electrodialysis, belonging to the field of fiber production and membrane separation technology. The method and system integrate a selective electrodialysis device into a traditional coagulation bath circulation system. Utilizing an ion exchange membrane with monovalent and divalent cation selectivity, sodium ions accumulated in the coagulation bath are selectively migrated and removed under the action of an electric field, while divalent metal ions are efficiently retained, thereby maintaining a stable molar ratio of divalent ions to sodium ions in the coagulation bath within the required process range. Compared to traditional methods, this invention eliminates the need for large-scale replenishment of divalent metal salts or full replacement solution, significantly reducing production costs and resource waste. It achieves online regeneration and continuous circulation of the coagulation bath, significantly improving production stability, fiber quality, and resource utilization efficiency, and is suitable for the green and efficient production of various alginate fibers.

The invention provides a device and method for treating rare earth tailing leaching wastewater through electrodialysis, the device comprises an electrodialysis unit, the electrodialysis unit comprises a first bipolar membrane, an anion exchange membrane, a monovalent selective cation exchange membrane and a second bipolar membrane which are sequentially arranged at intervals to form a cavity, the chamber sequentially comprises an anode chamber, a first concentration chamber, a feed liquid chamber, a second concentration chamber and a cathode chamber in the direction from the first bipolar membrane to the second bipolar membrane. According to the device and the method provided by the invention, the univalent selective cation exchange membrane is coupled with the bipolar membrane, so that the separation of NH4 < + > and Mg < 2 + > in the rare earth tailing leaching wastewater is realized, the current efficiency and the overall separation effect are improved, the energy-saving effect is achieved, and the problem of secondary pollution is avoided.

The invention provides a preparation method of lithium hydroxide, and relates to the technical field of salt lake lithium extraction. The preparation method of the lithium hydroxide comprises the following steps: S1, uniformly mixing a nanofiltration concentrated solution with a lithium precipitation mother solution, carrying out heating reaction, and filtering to obtain a mixed solution A; s2, the mixed solution A is subjected to impurity removal through a resin column, and a mixed solution B is obtained; s3, concentrating and crystallizing the mixed solution B to obtain a mixed solution C; s4, adding an acid solution into the mixed solution C to adjust the pH value, and then performing electrodialysis to obtain a mixed solution D; s5, the mixed solution D is subjected to boron removal through a resin column, and a purified solution is obtained; s6, the purified liquid is subjected to bipolar membrane electrodialysis, and a lithium hydroxide solution and an acid solution are obtained; and S7, evaporating, concentrating, crystallizing and centrifuging the lithium hydroxide solution to obtain lithium hydroxide. According to the method, the nanofiltration concentrated liquor and the lithium precipitation mother liquor are used for treating wastes with wastes, so that efficient recovery of lithium and green preparation of lithium hydroxide are realized.