Electro-driven membrane reaction method and device based on coupling of solid dissolution equilibrium and electromigration

Abstract

The application discloses an electrically driven membrane reaction method and device based on coupling of solid dissolution equilibrium and electromigration, and belongs to the technical field of membrane separation and electrochemistry engineering. The method mixes low-solubility solid raw material containing target ions and solvent to form a solid-liquid coexisting feed system, and introduces the solid feed chamber. After a direct current electric field is applied, the target ions near the membrane interface of the feed side are selectively migrated and consumed, the local ion activity is reduced, the dissolution equilibrium of the solid raw material is broken, and the continuous dissolution of the solid raw material is induced to release the target ions; the migrated target ions and the paired ions are recombined in the target product chamber to generate a target electrolyte product. The device is provided with a solid particle interception structure in the feed chamber or a circulating pipeline thereof, and the circulating volume of the feed chamber is greater than that of the product chamber. The application can directly utilize low-solubility solid raw material to prepare high-solubility electrolyte products, the raw material has wide applicability, the operation is stable, and the product concentration is high.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation and electrochemical engineering technology, specifically relating to an electro-driven membrane reaction method and apparatus based on the coupling of solid dissolution equilibrium and electromigration. Technical Background Strong bases and other highly soluble electrolyte products are essential basic chemicals in chemical, metallurgical, papermaking, textile, environmental remediation, new energy material preparation, and resource recycling processes. Developing low-energy-consumption, low-side-reaction-risk methods for electrolyte preparation or conversion applicable to various raw material systems has significant industrial and environmental application value.

[0002] Currently, the industrial preparation of strong alkalis and related electrolytes mainly relies on the following technical routes: Chlor-alkali electrolysis is the mainstream process for large-scale industrial production of sodium hydroxide. This method involves electrolyzing a sodium chloride solution, reducing water to hydroxide ions (OH-) at the cathode. - Simultaneously, chlorine gas is released from the anode side. This process is highly mature, but it consumes a lot of electricity, and the chlorine release reaction at the anode places strict requirements on equipment corrosion prevention and by-product control.

[0003] The causticization method uses sodium carbonate and calcium hydroxide (lime slurry) as raw materials, producing sodium hydroxide through a metathesis reaction, with calcium carbonate precipitate as a byproduct. This method involves multiple unit operations such as precipitation separation, solid-liquid treatment, and byproduct disposal, resulting in a long process flow, and the utilization or disposal of byproducts increases production costs.

[0004] Bipolar membrane electrodialysis (BMED) generates H+ through water dissociation at the bipolar membrane interface. + and OH - This method can be used to directly prepare acids and bases from salt solutions. The principle is clear and the process is relatively simple, but it still relies on an electric field to drive the water dissociation process at the bipolar membrane interface. Factors such as membrane interface polarization, energy consumption, and membrane cost limit its economic viability and applicability to some extent.

[0005] Furthermore, existing technologies have also proposed methods for preparing sodium hydroxide using four-compartment metathesis electrodialysis (EDM). For example, Chinese patent application CN113023750A discloses an apparatus and method for producing sodium hydroxide using electrodialysis, which uses a saturated calcium hydroxide solution or ammonia water as the first raw material and a sodium chloride solution as the second raw material. Through the selective migration of cation exchange membranes and anion exchange membranes, the dissolved Ca2+... 2+ / NH4 + with Na + OH - With Cl - Spatial rearrangement occurs, generating NaOH and CaCl2 / NH4Cl respectively. This method does not rely on water electrolysis or bipolar membrane water dissociation to generate OH.- While it has certain energy consumption advantages, this scheme mainly uses a completely dissolved saturated homogeneous solution as the feed system and does not utilize undissolved solid particles to build a continuous ion reservoir, thus it cannot directly process slurries or suspensions with solid-liquid coexistence.

[0006] However, the electro-driven membrane processes in the aforementioned prior art all use a homogeneous ionic solution that is completely or substantially dissolved as the feed material. The electro-driven membrane mainly performs the functions of selective migration, separation, and recombination of dissolved ions, and does not involve the direct utilization and conversion of undissolved solids.

[0007] For low-solidity solid feedstocks such as calcium hydroxide, magnesium hydroxide, calcium carbonate, and lithium carbonate, directly introducing them into an electro-driven membrane system presents a series of technical challenges. On the one hand, the release of ions from solid feedstocks is controlled by factors such as dissolution equilibrium, solid-liquid interface mass transfer, particle size, solid content, and fluid disturbance. The release rate may be lower than the ion migration and consumption rate at the membrane interface under the influence of an electric field, leading to local ion deficiency, increased concentration polarization, abnormal voltage rise, or enhanced side reactions. On the other hand, after solid particles enter the membrane stack with the circulating liquid, they may cause membrane surface deposition, flow channel blockage, or local scaling, affecting the continuous operation stability of the device.

[0008] Therefore, existing technologies still lack an electro-driven membrane reaction method and apparatus that can directly utilize low-solubility solids, suspensions, slurries, or solid-liquid coexistence feeding systems, and achieve the synergistic coupling of continuous dissolution and release of solid raw materials, selective ion migration, and target product generation. Summary of the Invention

[0009] The purpose of this invention is to provide an electro-driven membrane reaction method and apparatus based on the coupling of solid dissolution equilibrium and electromigration. It aims to overcome the limitation of existing electro-driven membrane processes that can only handle homogeneous solutions. By inducing the continuous dissolution and release of target ions through electromigration consumption of low-solubility solid raw materials, the stable preparation of target electrolyte products can be achieved in a solid-liquid coexistence feeding system.

[0010] On the one hand, this invention provides an electro-driven membrane reaction method based on the coupling of solid dissolution equilibrium and electromigration, employing the following technical solution: An electro-driven membrane reaction method based on the coupling of solid-state dissolution equilibrium and electromigration includes the following steps: 1) Mix the low-solubility solid raw material containing the target ion with a solvent to form a feeding system that exists at least partially in the form of solid particles, suspensions, slurries or solid-liquid coexistence. 2) The feeding system is introduced into the solid feeding chamber of the electrically driven membrane reactor, and an electrolyte solution containing paired ions is introduced into the paired ion feeding chamber; 3) Apply a DC electric field to selectively migrate and consume target ions near the membrane interface in the solid feed chamber through the ion exchange membrane. The local activity of the corresponding ions in the feed system decreases accordingly, breaking the dissolution equilibrium of the low-solubility solid raw material and inducing the solid raw material to continuously dissolve and release target ions. 4) The migrated target ions recombine with the paired ions from the paired ion feed chamber in the product chamber to generate the target electrolyte product.

[0011] Preferably, in step 1), the low-solidity solid raw material is at least one of alkaline earth metal oxides, alkaline earth metal hydroxides, slightly soluble salts, sparingly soluble salts, mineral raw materials, and industrial by-product solids.

[0012] Preferably, in step 1), the low-solidity solid raw material is an alkaline earth metal oxide; The alkaline earth metal oxide undergoes an in-situ hydration reaction with water in the feeding system to generate alkaline earth metal hydroxide, and the target ion is continuously released through the dissolution equilibrium of the alkaline earth metal hydroxide.

[0013] Preferably, by adjusting at least one of the parameters of current density, feed flow rate, particle size, solid content, and compartment volume ratio, the ion release rate of the low-solidity solid raw material is matched with the ion migration and consumption rate under the action of the electric field.

[0014] On the one hand, the present invention provides an electrically driven membrane reaction apparatus for implementing the above-described electrically driven membrane reaction method, which adopts the following technical solution: An electrically driven membrane reactor includes a DC power supply, an anode, a cathode, an electrode liquid circulation system, and an ion exchange membrane stack. The ion exchange membrane stack is divided by alternating cation exchange membranes and anion exchange membranes to form at least one electrode chamber, at least one low-solubility solid feed chamber, at least one paired ion feed chamber, at least one target product chamber and at least one common product chamber; The low-solubility solids feeding chamber or its circulation pipeline is equipped with a solid particle interception structure to retain undissolved solid particles in the feeding circulation system.

[0015] Preferably, the compartments of the ion exchange membrane stack are arranged as follows: electrode compartment, cation exchange membrane, target product compartment, anion exchange membrane, low-solubility solid feed compartment, cation exchange membrane, common product compartment, anion exchange membrane, paired ion feed compartment, cation exchange membrane, and electrode compartment.

[0016] Preferably, the solid particle trapping structure is at least one of a sieve, a filter, a porous baffle, a settling zone, a hydrocyclone separator, or an external solid-liquid separator.

[0017] Preferably, the circulation volume of the low-solidity solids feeding chamber is greater than the circulation volume of the target product chamber, and the circulation volume ratio of the low-solidity solids feeding chamber to the target product chamber is 2:1 to 100:1.

[0018] On the other hand, the present invention provides the application of the above-mentioned electro-driven membrane reaction method in the preparation of strong bases, salt conversion, resource utilization of concentrated brine, conversion of low-solubility mineral raw materials, or resource utilization of industrial by-product solids.

[0019] In summary, the present invention has the following beneficial technical effects: 1. This invention achieves the functional separation of the target ion supply process and the electric field migration process. The target ions originate from the chemical potential and dissolution equilibrium inherent in the low-solidity solid raw material. The applied electric field is only used to selectively migrate the released ions, and by continuously consuming ions near the membrane interface to reduce local activity, it disrupts the solid dissolution equilibrium to induce continuous dissolution and release, fundamentally changing the energy utilization mode and raw material applicability boundaries of the electro-driven membrane process. Specifically, OH... - The source of the substance is not the electrode reaction or bipolar film water dissociation, but rather the chemical potential (dissolution equilibrium) inherent in the low-solubility solid raw material itself. Electrical energy is only used to drive the selective migration and spatial rearrangement of released ions, rather than for the electrochemical generation of OH-. - .

[0020] 2. This invention directly uses low-solubility solids, suspensions, slurries, or solid-liquid coexistence systems as feedstocks, without the need to pre-convert solids into completely dissolved ionic solutions. The solid raw materials serve as a continuous ion reservoir, and their dissolution and release rates are dynamically regulated by the electromigration consumption rate, thus completely solving the technical bottleneck of traditional electro-driven membrane technology that cannot directly utilize slightly soluble or sparingly soluble solid raw materials.

[0021] 3. This invention features a device structure that differs from existing technologies for solid-liquid multiphase flow operation, including: a solid particle trapping structure (such as a screen, filter, or settling zone) located in the feed chamber or circulation pipeline to retain undissolved solid particles in the feed circulation system; anti-clogging structures such as wide flow channels, anti-deposition baffles, and high-shear circulation channels suitable for solid-liquid multiphase flow operation; and an asymmetric volume configuration where the feed circulation volume for low-solidity solids is larger than the product chamber circulation volume. These device features are not simple structural replacements, but rather a systematic design necessary for achieving stable and continuous operation of the solid-liquid coexistence feed system in an electrically driven membrane device.

[0022] 4. This invention adopts a batch operation mode, which utilizes the continuous dissolution and release of solid raw materials in a large-volume feed tank to maintain long-term feed capacity, and can achieve continuous accumulation of target products without the need for continuous replenishment of solids or saturated solutions.

[0023] 5. The core of the coupling mechanism of this invention is "electromigration consumption reduces local ion activity, promoting the continuous dissolution of low-solubility solid phases". This mechanism is not limited to alkaline earth metal oxide hydration systems; carbonates, sulfates and other slightly / insoluble salts, various metal-containing minerals, and calcium- and magnesium-containing industrial solid slags also have solid-liquid dissolution equilibrium, and all can use this device and process to achieve continuous ion release and electrolyte recombination. Therefore, the range of raw materials can cover the above categories. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structural distribution of a metathesis electrodialysis reactor based on the coupling of solid dissolution equilibrium and electromigration. Figure 2 A schematic diagram of a solid particle trapping structure and an anti-clogging feed channel suitable for solid-liquid multiphase feeding; Figure 3 A schematic diagram of an asymmetric volume configuration of a large-volume supply chamber and a small-volume product chamber; Figure 4 A schematic diagram illustrating the principle of product purity and ion leakage detection; Figure 5 A schematic diagram illustrating the mechanism of electromigration-induced continuous dissolution and release of target ions from low-solubility solid raw materials; Figure 6 This is a schematic diagram of the selective migration of ions and product recombination in the CaO / Ca(OH)2-NaCl system. Figure 7 The graph shows the change in NaOH concentration in the target product chamber over time in Test Example 2. Figure 8 This is a graph showing the change in solution volume in each circulation chamber over time in Test Example 2. Figure 9 This is a comparison chart of the continuous supply capacity of the solid-liquid coexistence feeding system under different CaO dosages in Test Example 4. Figure 10 This is a comparison chart of voltage recovery before and after backwashing under filterless conditions; Figure 11 This is a comparison chart of operational stability under conditions of no and no solid particle trapping structure in Test Example 5; Figure 12 The graph shows the change in NaOH concentration in the target product chamber with operating time under different current densities in Test Example 7. Figure 13 In the middle, 'a' represents a comparison of net NaOH production. Figure 13 In the middle, b is a comparison chart of current efficiency; Figure 13 The graph in section c is a comparison of unit energy consumption; Figure 14The graph shows the change in volume of the alkali production circulation chamber under different current densities as a function of operating time in Test Example 7. Figure 15 For the target product chamber and common product chamber under different current densities, 24h Cl - Concentration comparison chart; Figure 16 Dissolved Ca in a highly alkaline environment 2+ Theoretical solubility upper limit estimation chart; Figure 17 The graph shows the change in conductivity of each chamber in the MgO-NaCl system over time. Figure 18 The target product chamber conductivity and OH content of the MgO system - Concentration variation over operating time; Figure 19 The graph shows the change in operating voltage over time for the MgO-NaCl system. Detailed Implementation

[0025] The embodiments of the present invention will be described in detail below. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation schemes and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0026] Example Example 1 Reference Figure 1 The structure of an electrically driven membrane reactor includes a DC power supply, an anode, a cathode, an electrode liquid circulation system, and an ion exchange membrane stack. The ion exchange membrane stack is divided by alternating cation exchange membranes and anion exchange membranes, forming at least one electrode chamber, at least one low-solidity solid feed chamber, at least one paired ion feed chamber, at least one target product chamber, and at least one common product chamber. Depending on the requirements of different raw materials and products, the ion exchange membrane stack can adopt a single-stage structure, a multi-stage structure, a repeating unit structure, a series structure, or a parallel structure. Reference Figure 1 The ion exchange membrane stack is arranged in the following compartments: electrode compartment, cation exchange membrane, target product compartment, anion exchange membrane, low-solidity solid feed compartment, cation exchange membrane, common product compartment, anion exchange membrane, paired ion feed compartment, cation exchange membrane, and electrode compartment. In this embodiment, the cation exchange membrane is a Tianwei homogeneous cation exchange membrane, and the anion exchange membrane is an indigo-dyed homogeneous anion exchange membrane. The effective area of ​​a single membrane is 64 cm². 2(e.g., 8cm × 8cm), membrane spacing (shim thickness) is 0.5mm. Wherein, E is the electrode chamber, CEM is the cation exchange membrane, AEM is the anion exchange membrane, C1 is the target product chamber, F1 is the low-solidity solid feed chamber, C2 is the common product chamber, and F2 is the paired ion feed chamber.

[0027] Reference Figure 2 The low-solids feed chamber or its circulation pipeline is equipped with a solid particle retention structure. This structure includes, but is not limited to, screens, filters, porous baffles, settling zones, hydrocyclones, external solid-liquid separators, or combinations thereof. It is used to retain undissolved solid particles in the feed circulation system, reducing the risk of solid particles entering the intermembrane channels of the ion exchange membrane stack and causing deposition, scaling, or blockage. The low-solids feed chamber employs a structure suitable for multiphase flow operation, including but not limited to wide-channel structures, mesh support structures, anti-deposition baffles, high-shear circulation channels, tangential feed structures, or turbulence structures, to enhance feed liquid agitation, reduce the concentration boundary layer thickness, lower the risk of solid particle deposition, and improve the matching of ion release and migration processes. The solid particle interception structure preferably uses a 150-200 mesh stainless steel filter screen or a porous baffle with a pore size of 50-200μm; the flow channel width of the wide flow channel structure is preferably 2-5mm, and the grid spacing of the grid support structure is preferably 5-10mm; the Reynolds number of the high shear circulation channel is controlled between 2000-10000 to ensure sufficient fluid disturbance.

[0028] Reference Figure 3 The circulation volume of the low-solidity solids feed chamber is larger than that of the target product chamber. The ratio of the circulation volumes of the low-solidity solids feed chamber to the target product chamber can be 2:1 to 100:1 to maintain a continuous supply of target ions while reducing the initial volume of the target product chamber and increasing the accumulation concentration of the target electrolyte product. The asymmetric volume configuration is designed based on the unavoidable water migration phenomenon during the electro-driven membrane process. Under the influence of an electric field, ions migrate along the hydration membrane, leading to an increase in the product chamber volume and a decrease in the feed chamber volume. By setting a large-volume feed chamber (2-100 times the product chamber volume), long-term feed capacity can be maintained without frequent replenishment; at the same time, the small-volume product chamber can reduce the dilution effect caused by water migration and increase the product concentration. Experiments show that when the volume ratio is less than 2:1, the product dilution effect is significant; when the volume ratio is greater than 100:1, the equipment size is too large, and the economic efficiency decreases.

[0029] In addition, the target product chamber, common product chamber, and their circulation system in this embodiment can be equipped with airtight seals, inert gas protection, one-way breathing structures, or carbon dioxide isolation structures to reduce the risk of carbonation, precipitation, or secondary scaling of the target product caused by CO2 entering the system. Combined with Figure 4To quantitatively evaluate membrane selectivity and product purity, an ion sampling and detection system was developed to detect the target product Ca in the laboratory. 2+ Cl - Carbonate, common product indoor Na + OH - Determine membrane leakage and product purity.

[0030] Example 2 This embodiment provides an electro-driven membrane reaction method based on the coupling of solid dissolution equilibrium and electromigration, including the following steps: S1. Mix the low-solubility solid raw material containing the target ion with water or a corresponding solvent to form a solid, suspension, slurry or solid-liquid coexistence feeding system; it should be noted that the low-solubility solid raw material in this embodiment refers to a solid with a solubility of no more than 10 g / L in water at 25°C, or a solid raw material that can form a low-solubility hydroxide / salt solid phase reservoir after contact with water. For oxides with a relatively fast hydration rate, such as CaO, they can be directly added to water and stirred for 5-10 minutes to form a uniform slurry. For oxides with a relatively slow hydration rate, such as MgO, they can be stirred and hydrated at 60-80℃ for 1-2 hours, or a small amount of hydration accelerator (such as CaCl2) can be added to speed up the hydration rate.

[0031] S2. The low-solidity solid feed system and the electrolyte feed solution containing paired ions are introduced into different compartments of the electrically driven membrane reactor, respectively. The paired ion feed solution may contain Na+. + K + Cl - NO3 - SO4 2- Or other easily soluble salt solutions of migratable paired ions.

[0032] S3. Apply a DC electric field to achieve selective migration of target ions through cation exchange membranes and anion exchange membranes. As relevant ions near the membrane interface on the feed side are continuously migrated and consumed, the dissolution equilibrium of the low-solidity solid feedstock is continuously disturbed, prompting it to continue releasing corresponding ions, thus forming a coupled process of "solid feedstock dissolution and release - membrane selective migration"; Reference Figure 5 Taking Ca(OH)₂ as an example, its dissolution equilibrium can be expressed as: Ca(OH)2(s) Ca 2+ +2OH - The solubility product relationship is: Ksp = aCa 2+ a 2 OH - .

[0033] Reference Figure 6 Taking the CaO / Ca(OH)2-NaCl system as an example: CaO in the low-solidity solid feed chamber is hydrated in situ to generate Ca(OH)2, and OH is continuously released through the Ca(OH)2 dissolution equilibrium. - and Ca 2+ The paired ion feed chamber provides Na + and Cl - ;OH - with Na + NaOH and Ca accumulate in the target product chamber to form NaOH; 2+ With Cl - In the common product chamber, a common product solution with CaCl2 as the main component is enriched and formed.

[0034] S4. The released and migrated ions recombine with paired ions in another feed solution in the target product chamber to form the target electrolyte product and the co-product. The target electrolyte products include, but are not limited to, sodium hydroxide, potassium hydroxide, calcium chloride, magnesium chloride, nitrates, sulfates, or other highly soluble electrolyte products formed by ion recombination. By adjusting the current density, feed flow rate, circulation intensity, particle size, solid content, membrane configuration, compartment volume ratio, and running time, the ion release rate of low-solubility solid feedstock is matched with the ion migration and consumption rate under the action of electric field, thereby reducing the risks of local ion deficiency, concentration polarization, abnormal voltage rise, water dissociation side reaction, membrane fouling, and flow channel blockage. The matching of ion release rate and migration consumption rate can be judged by the following indicators: 1. The system voltage remains stable during operation without continuous spikes; 2. The target product concentration increases approximately linearly with time (at least for the first 6-12 hours); 3. The current efficiency remains above 50%. If the voltage continues to rise or the product concentration growth stagnates, it indicates that the migration consumption rate is greater than the release rate, and the current density should be reduced or the solid dosage increased; if the product concentration increases slowly and the current efficiency is low, it indicates that the release rate is greater than the migration consumption rate, and the current density should be appropriately increased. Current density can be 10-1000 A / m 2 Preferably 50-300A / m 2 Further preferred is 100-200 A / m 2 Excessive current density can lead to intensified concentration polarization, enhanced water migration, or increased side reactions, while insufficient current density will prevent the full utilization of the ion-supplying capacity of the solid feedstock. The solid content of the feeding system can be adjusted according to the solubility and release rate of the feedstock, preferably 0.1-200 g / L. The particle size of low-solidity solid feedstocks can be controlled by crushing, sieving, or dispersion treatment, preferably with a D50 of 0.1-500 μm.

[0035] Test case Test Example 1 Feasibility verification of electro-driven membrane alkali production under the condition of in-situ hydration of 10g CaO.

[0036] This test case illustrates the feasibility of using CaO as a low-solubility solid raw material to generate Ca(OH)2 through in-situ hydration and to achieve NaOH accumulation in an electrically driven membrane system.

[0037] The experiment employed a four-compartment metathesis electrodialysis membrane stack. The stack compartments sequentially included an electrode compartment, a target product compartment, a low-solidity solids feed compartment, a common product compartment, a paired ion feed compartment, and another electrode compartment. The ion exchange membrane stack contained both cation exchange and anion exchange membranes to allow OH- to pass through. - Ca 2+ Na + and Cl - Selective migration occurs under the influence of a DC electric field.

[0038] The low-solubility solids feeding system is formed by adding 10g CaO to water. CaO hydrates in situ in the water to generate Ca(OH)2, and OH- is released through the dissolution equilibrium of Ca(OH)2. - and Ca 2+ The paired ion feed chamber contains a 1 mol / L NaCl solution, the target product chamber initially contains a 0.01 mol / L NaOH solution, the co-product chamber initially contains a 0.01 mol / L CaCl2 solution, and the electrode chamber contains a 0.2 mol / L Na2SO4 solution. The operating current density is 100 A / m. 2 The circulation flow rate of the low-solidity solids feed chamber, the paired ion feed chamber, the target product chamber, and the common product chamber is 10 L / h, and the circulation flow rate of the electrode chamber is 15 L / h.

[0039] During the experiment, CaO in the low-solidity solid feeding chamber hydrated in situ, forming a CaO / Ca(OH)₂ solid-liquid coexistence system. Under the influence of an electric field, OH₂ in the low-solidity solid feeding chamber... - Na migrates through the anion exchange membrane to the target product chamber, where paired ion feeds are located. + It migrates through the cation exchange membrane to the target product chamber and accumulates there to form NaOH; simultaneously, Ca in the low-solidity solid feed chamber... 2+ Cl in the paired ion feed chamber - They migrate to the common product chamber and are enriched in the common product chamber to form a common product solution with CaCl2 as the main component.

[0040] Experimental results showed that the conductivity of the target product chamber increased from an initial 6.019 mS / cm to 105.3 mS / cm after 2 hours, indicating significant alkali accumulation in the target product chamber. During operation, the conductivity of the paired ion feed chamber gradually decreased from 82.89 mS / cm to 49.03 mS / cm, indicating continuous consumption of the NaCl salt source; the conductivity of the common product chamber increased from 6.254 mS / cm to 76.46 mS / cm, indicating ion enrichment in the common product chamber.

[0041] This embodiment demonstrates that CaO can serve as a low-solubility solid alkali source, participating in the spatial recombination of NaOH and CaCl2 through in-situ hydration and dissolution release in an electrically driven membrane system.

[0042] Test Example 2 24-hour continuous operation verification under the condition of direct addition of 30g CaO.

[0043] This test case illustrates the continuous operation capability and product accumulation effect of the electro-driven membrane system under the condition of in-situ CaO hydration feed of 30g CaO.

[0044] The experimental setup was the same as in Test Example 1. 30g of CaO was directly added to the low-solidity solid feed chamber to form a CaO / Ca(OH)₂ solid-liquid coexistence feed system; the paired ion feed chamber was a 1mol / L NaCl solution; the target product chamber was a NaOH target product chamber with an initial volume of 160mL and an initial NaOH concentration of 0.013mol / L; the common product chamber was a CaCl₂ common product chamber with an initial volume of 175mL; and electrode chamber E was a Na₂SO₄ electrode liquid chamber. The operating current density was 100A / m². 2 The circulation flow rate was 10 L / h, and the circulation flow rate in the electrode chamber was 15 L / h. The experiment was run continuously for 24 hours, and samples were taken and recorded at 0, 1, 2, 3, 4, 6, 12 and 24 hours.

[0045] Reference Figure 7 During the experiment, the concentration of NaOH in the target product chamber continuously increased. Titration results showed that the NaOH concentration in the target product chamber increased from an initial 0.013 mol / L to 0.198 mol / L at 1 h, 0.383 mol / L at 2 h, 0.506 mol / L at 3 h, 0.738 mol / L at 4 h, 1.012 mol / L at 6 h, and 1.299 mol / L at 12 h, reaching 1.322 mol / L at 24 h. The conductivity of the target product chamber at 2 h, 4 h, 6 h, 12 h, and 24 h was 81.18, 134.40, 173.85, 218.7, and 234.4 mS / cm, respectively, and the pH of the target product chamber at 24 h was 14.12.

[0046] Meanwhile, the system voltage ranged from approximately 5.06 to 7.16 V during the 0-24h period, without any long-term uncontrolled increase.

[0047] Reference Figure 8 , Figure 8 Using 0h as the baseline, the evolution of solution volume changes in each circulation chamber over time in this test example is shown. As can be seen from the figure, in the initial stage of operation (0-4h), the overall volume changes in each circulation chamber were relatively small, indicating a gradual adjustment phase. With increasing operation time, the volumes of the target product chamber (C1) and the common product chamber (C2) gradually increased, while the volumes of the low-solidity solid feed chamber (F1) and the paired ion feed chamber (F2) continuously decreased, and the electrode solution chamber (E) only decreased slightly. Specifically, the volume changes of C1 at 6h, 12h, and 24h were approximately +27mL, +67mL, and +220mL, respectively, showing the most significant increase; C2 at the corresponding times were approximately +28mL, +50mL, and +130mL, respectively, exhibiting a relatively gradual increase. Meanwhile, the volume changes of F1 at 6h, 12h, and 24h were approximately... 90mL 180mL and 300mL, F2 is approximately 60mL 90mL and 310 mL. The above results indicate that there is continuous directional water migration during operation, and the asymmetric volume configuration of a large-volume supply tank and a small-volume product chamber is beneficial for maintaining the feeding capacity and promoting product accumulation.

[0048] The above results indicate that there is a certain amount of water migration or solution migration during operation. Therefore, adopting an asymmetric volume configuration where the circulation volume of the low-solidity solid feed chamber is larger than that of the target product chamber is beneficial to maintaining the CaO / Ca(OH)2 supply capacity and promoting the accumulation of the target alkali solution in the target product chamber.

[0049] This test case further illustrates that the in-situ hydration of CaO, the dissolution and release of Ca(OH)2, and the electromigration process can be coupled over a relatively long operating period, achieving continuous accumulation of NaOH.

[0050] Furthermore, after 24 hours of operation, a disassembly and inspection revealed no obvious abnormalities on the membrane surface, and no chemical scaling of Ca(OH)2 or CaCO3 was observed. Backflushing at the inlet removed the accumulated particles, and the voltage dropped significantly, indicating that the periodic voltage increases during operation were due to reversible physical blockage, rather than irreversible chemical deposition on the membrane surface.

[0051] This test example further demonstrates that OH -The source of the substance is not the electrode reaction or bipolar film water dissociation, but the inherent chemical potential (dissolution equilibrium) of CaO / Ca(OH)2. The applied electrical energy is only used to drive the selective migration and spatial rearrangement of the released ions, not for the electrochemical generation of OH-. - This achieves functional decoupling of ion supply and ion migration.

[0052] Test Example 3 150A / m at a CaO dosage of 20g 2 Current density optimized operation.

[0053] This test case illustrates the sustained production capacity of the CaO / Ca(OH)2 solid-liquid coexistence feed system in an electrically driven membrane reactor under preferred current density conditions.

[0054] The experimental setup was the same as in Test Example 1. 20g of CaO was directly added to the low-solidity solid feed chamber to form a solid-liquid coexistence feed system. The paired ion feed chamber contained a 1mol / L NaCl solution, the target product chamber initially contained a 0.01mol / L NaOH solution, the co-product chamber initially contained a 0.01mol / L CaCl2 solution, and electrode chamber E contained a 0.2mol / L Na2SO4 solution. The operating current density was 150A / m². 2 The circulation flow rate in each circulation chamber was 10 L / h, and the circulation flow rate in the electrode chamber was 15 L / h. The experiment ran continuously for 17 hours.

[0055] Experimental results show that the NaOH concentration in the target product chamber continuously increases. Under the condition of equal charge comparison (input charge 7.68Ah), 100A / m 2 After 12 hours of operation, the net NaOH production was 0.3427 mol, 150 A / m 2 After 8 hours of operation, the net NaOH production reached 0.3591 mol, 200 A / m 2 After 6 hours of operation, the net NaOH production was 0.2930 mol. (150 A / m) 2 Under these conditions, the current efficiency reaches 62.66%, and the unit energy consumption is reduced to 3.55kWh / kg, demonstrating the best overall performance.

[0056] Further extend 150A / m 2 After 17 hours of operation, the NaOH concentration in the target product chamber reached 1.66 mol / L, the net NaOH production reached 0.7362 mol, and the current efficiency remained at 60.45%.

[0057] This result indicates that 150 A / m 2Under these conditions, a good synergistic match is formed between the CaO dissolution and release rate and the electromigration consumption rate, which not only improves the product generation rate but also avoids polarization and energy consumption caused by excessively high current density, and has good continuous production capability.

[0058] Test Example 4 Comparison of the continuous supply capacity of solid-liquid coexistence feeding systems under different CaO dosages.

[0059] This test example illustrates that low-solubility solid raw materials not only exist as initial feed in this invention, but can also participate in the "dissolution-release-electromigration coupling" process as a continuous ion reservoir; it also shows that the amount of CaO added affects the matching relationship between the ion release rate, the electromigration consumption rate, and the NaOH accumulation capacity in the target product chamber in the solid-liquid coexistence system.

[0060] Under the same feeding method, ion exchange membrane stack structure, and current density (100A / m²), 2 Under the following conditions: circulation flow rate (10 L / h), salt source concentration in the paired ion feed chamber (1 mol / L NaCl), and initial conditions in the target product chamber, solid-liquid coexistence feed systems of 10 g, 20 g, and 30 g CaO were set up, respectively. All three experiments employed the method of directly adding CaO to the low-solidity solid feed chamber, allowing CaO to hydrate in situ in water to generate Ca(OH)₂, thus forming a CaO / Ca(OH)₂ solid-liquid coexistence feed system.

[0061] Reference Figure 9 The experimental results are as follows: Under 10g CaO conditions: the conductivity of the target product chamber reached 105.3mS / cm at 2h, 100.5mS / cm at 4h, and 96.66mS / cm at about 7h, indicating that the system can quickly start alkali production under low dosage conditions, but the conductivity plateaus in the later stage.

[0062] Under the condition of 20g CaO: the conductivity of the target product chamber at 2h, 4h, 6h, 12h, and 24h were 88.33, 150.6, 184.6, 217.2, and 208.6 mS / cm, respectively; the titration results showed that the NaOH concentration in the target product chamber increased from the initial 0.040 mol / L to 0.228 mol / L at 1h, 0.474 mol / L at 2h, 0.836 mol / L at 4h, 1.078 mol / L at 6h, 1.290 mol / L at 12h, and 1.204 mol / L at 24h. The slightly lower concentration at 24h than at 12h with a dosage of 20g is a true experimental phenomenon. This is because at this dosage, the solid stock is gradually depleted in the later stages, and the dilution effect caused by water migration leads to a slight decrease in concentration.

[0063] Under the condition of 30g CaO: the conductivity of the target product chamber at 2h, 4h, 6h, 12h and 24h were 81.18, 134.40, 173.85, 218.7 and 234.4 mS / cm, respectively; at 24h, the concentration of NaOH titrated in the target product chamber C1 reached 1.322 mol / L, and the pH of the target product chamber was 14.12.

[0064] The comparison of the above dosages of 10g, 20g, and 30g and the differences in their subsequent continuous concentration capabilities indicate that the continuous ion supply capacity under the low solid inventory condition of 10g CaO is insufficient; the medium dosage under the 20g CaO condition is sufficient to support the target product chamber to enter the high concentration NaOH product range (reaching 1.078mol / L in 6h and 1.290mol / L in 12h); the higher solid inventory under the 30g CaO condition is more conducive to maintaining the dynamic matching between Ca(OH)2 dissolution and release and electromigration consumption.

[0065] This comparative experiment demonstrates that the CaO dosage primarily affects the sustained supply capacity in the later stages, rather than simply the start-up speed. As the CaO dosage increases, the amount of undissolved solids in the solid-liquid coexistence feeding system increases, allowing for continued dissolution and release of OH- under electromigration consumption. - and Ca 2+ This improves the ability of NaOH to accumulate continuously in the target product chamber.

[0066] It should be noted that a higher CaO dosage is not always better. While increasing the solid dosage may improve the ion reservoir capacity, it may also increase the risk of particle deposition, inlet buildup, channel blockage, or voltage fluctuations. Therefore, the CaO dosage should be carefully matched with current density, circulation rate, solid particle trapping structure, channel structure, and operating time.

[0067] Test Example 5 Comparison of operational stability with and without solid particle trapping structures.

[0068] This test case demonstrates the necessity of a solid particle trapping structure in the low-solidity solids feed chamber or its circulation pipeline for the operation of solid-liquid multiphase systems.

[0069] This test case uses two independent experiments for comparative verification: Experiment 1 without a filter and Experiment 2 with a filter. The core performance indicators of Experiment 1 and Experiment 2 are compared in Table 1. The observation indicators include: voltage changes (to determine flow resistance and polarization changes), pressure drop and flow rate changes of ion exchange membrane stack (to determine the risk of flow channel blockage), membrane surface deposition and inlet particle accumulation (to determine particle retention effect), and voltage recovery before and after backwashing (to determine whether blockage or deposition is reversible).

[0070] Table 1 Core Operating Indicators

[0071] Reference Figure 10 and Figure 11 Although the voltage continued to rise without a filter, it dropped significantly after backwashing, indicating that the blockage was mainly due to reversible physical accumulation. After installing the solid particle interception structure, the voltage remained stable throughout the operation with no obvious signs of blockage.

[0072] From an operational mechanism perspective, the solid particle retention structure functions not merely as a filter for impurities, but as a key unit in maintaining the stable operation of the solid-liquid multiphase electrodialysis system. On one hand, this structure ensures that the solid feedstock remains primarily within the feed circulation zone, continuously replenishing the liquid phase with OH- through dissolution equilibrium. - On the other hand, it also prevents particles from directly entering the ion exchange membrane stack, causing blockage, deposition, and membrane fouling. Therefore, the solid particle retention structure achieves functional separation of "solids retained in the reaction zone and ions entering the migration zone," enabling stable coupling between the dissolution and release process and the electromigration process.

[0073] The results indicate that in metathesis electrodialysis systems involving low-solubility or slightly soluble solids, the lack of a solid particle retention structure leads to uncontrolled migration of solid particles, causing channel blockage, membrane deposition, and deteriorated mass transfer, resulting in reduced product concentration and decreased operational stability. Incorporating filters, screens, porous baffles, or external solid-liquid separation structures into the low-solubility solids feed chamber or its circulation pipeline can significantly reduce the risk of particles entering the ion exchange membrane stack, thereby improving conductivity and OH- ions. - The concentration growth rate is maintained, and high operational stability is maintained in the later stages.

[0074] Test Example 6 Determination of target product concentration and ion migration efficiency.

[0075] During the 24-hour continuous operation of Test Example 2, samples of the solutions in each compartment were taken for analysis. The concentration of NaOH in the target product compartment was determined by acid-base titration, and the conductivity of the solution in each circulation compartment was determined by a conductivity meter.

[0076] Reference Figure 4 The test results showed that the NaOH concentration in the target product chamber increased continuously from the initial 0.013 mol / L to 1.322 mol / L after 24 hours. The conductivity of the target product chamber increased from the initial 6.019 mS / cm to 234.4 mS / cm after 24 hours. The conductivity of the co-product chamber increased from the initial 3.958 mS / cm to 115.5 mS / cm. The conductivity of the paired ion feed chamber decreased from the initial 80.93 mS / cm to 65.55 mS / cm.

[0077] The direction of ion concentration change in each compartment is consistent with the theoretical migration path: low-solidity solids feed compartment, medium OH... - and Ca 2 + Na migrates separately to the target product chamber and the common product chamber, and Na in the paired ion feed chamber... + and Cl - The ions migrated to the target product chamber and the common product chamber respectively, demonstrating that the ion exchange membrane has the ability to selectively migrate to the target ions, and that the target ions can achieve spatial recombination in the membrane separation system.

[0078] Test Example 7 The effect of current density on the matching relationship between ion release rate and electromigration consumption rate.

[0079] To verify the matching relationship between the rate of ion release from CaO dissolution and the rate of ion migration and consumption driven by the electric field, under the same CaO dosage (20 g), NaCl concentration (1 mol / L), circulation flow rate (10 L / h), and ion exchange membrane stack structure, a 100 A / m 2 150A / m 2 and 200A / m 2 A comparative experiment was conducted using three sets of current densities.

[0080] Combination Figures 12 to 14 To eliminate the difference in input charge caused by different actual currents under different current densities, this experiment uses an equal current flow method for comparison. Specifically, 100A / m 2 Running under conditions for 12 hours, 150A / m 2 Running under conditions for 8 hours, 200A / m 2 The conditions were run for 6 hours, and the input charge for all three sets of conditions was 7.68 Ah. The test results are shown in Table 2.

[0081] Table 2 Test Results

[0082] (Note: The calculation method for net NaOH generation is n(OH)) - ,net)=C t V t C0 V0+n(sampling), where C t V t OH in C1 at each time point - Concentration and volume, n(sampling) is the cumulative replenishment amount consumed during sampling; the values ​​in the table are the solid supply path OH after deducting side reactions. - Net amount produced, not apparent alkali amount, is directly multiplied by volume. As shown in Table 2, at 100 A / m 2 Under these conditions, the electromigration driving force is low, and the NaOH formation rate is 0.0286 mol / h. The slow product formation rate indicates insufficient ion migration consumption rate, failing to fully utilize the ion supply capacity released by CaO dissolution. At 200 A / m 2 Under these conditions, although the initial NaOH formation rate increased to 0.0488 mol / h, the current efficiency decreased to 51.12%, and the unit energy consumption increased to 4.59 kWh / kg. Furthermore, subsequent operation showed a decrease in concentration or instability, indicating that at excessively high current densities, the electromigration consumption rate exceeded the CaO dissolution, release, and mass transfer replenishment capacity, easily leading to local ion depletion, enhanced concentration polarization, or increased side reactions. At 150 A / m... 2 Under these conditions, the net NaOH production reached 0.3591 mol, the current efficiency reached 62.66%, and the unit energy consumption decreased to 3.55 kWh / kg, demonstrating optimal overall performance. Further extending the 150 A / m... 2 After 17 hours of operation, the NaOH concentration in the target product chamber reached 1.66 mol / L, the net NaOH production reached 0.7362 mol, and the current efficiency remained at 60.45%.

[0083] Therefore, when the current density is too low, the electromigration consumption is insufficient, resulting in a low product formation rate; when the current density is too high, the ion supply is insufficient, which easily leads to concentration polarization and increased energy consumption. Under a moderate current density, ion release and electromigration consumption can form a good dynamic match, thereby achieving synergistic optimization of NaOH yield, current efficiency and unit energy consumption.

[0084] Test Example 8 The effect of asymmetric volume configuration on product concentration accumulation.

[0085] Reference Figure 3 and Figure 8 The volume changes of each circulation chamber in test example 2 were recorded and analyzed.

[0086] Test results showed that the target product chamber volume increased from the initial 160 mL to 380 mL after 24 hours, the co-product chamber volume increased from 175 mL to 305 mL, the low-solids feed chamber volume decreased from 4.98 L to 4.68 L, and the paired ion feed chamber salt source chamber volume decreased from 980 mL to 670 mL. The ratio of the circulation volume of the low-solids feed chamber (approximately 5 L) to the initial volume of the target product chamber (160 mL) was approximately 30:1.

[0087] The NaOH concentration increased from 0.013 mol / L to 1.012 mol / L within 6 hours, while the volume of the target product chamber only increased by about 2.4 times. The increase in concentration was much greater than the increase in volume.

[0088] The above results indicate that using an asymmetric volume configuration where the circulation volume of the low-solidity solid feed chamber is larger than that of the target product chamber can effectively reduce the initial dilution of the target product chamber and promote the accumulation of the target electrolyte product concentration while maintaining the continuous supply capacity of low-solidity raw materials.

[0089] Test Example 9 This test case independently verifies both the system with and without a filter.

[0090] It has a filter system: Test results showed that the system voltage ranged from approximately 5.06 to 7.16 V during 0-24 hours, without any sustained uncontrolled increase. After adopting the combined filter and funnel trapping structure, the feed circulation system showed no significant blockage during 24 hours of continuous operation. Upon disassembly and inspection after the 24-hour operation, no obvious abnormalities were found on the membrane surface; no chemical scaling or precipitation was observed. Backwashing at the inlet removed accumulated particles, and the voltage dropped significantly.

[0091] The above results indicate that, under controlled particle size, solid content, flow rate, and solid particle retention structure, the solid-liquid coexistence feeding system can achieve 24-hour continuous operation in the ion exchange membrane stack; the staged voltage increase mainly originates from reversible physical deposition at the inlet structure, rather than irreversible chemical deposition on the membrane surface.

[0092] Filterless system: Backwashing was performed periodically without a filter, and the voltage changes before and after backwashing at each time point are shown in Table 3 below.

[0093] Table 3 Voltage Change Table

[0094] The voltage dropped significantly after backflushing, indicating that the voltage increase was mainly related to the reversible physical blockage of solid particles; however, the voltage did not fully recover to the initial level after 24 hours, suggesting that some irreversible deposits or slight fouling of the membrane surface may exist after long-term operation.

[0095] Test Case 10 Product purity and ion leakage detection.

[0096] To evaluate the composition and impurity levels of the target product obtained in this invention, the anionic composition of the target product chamber (C1) and common product chamber (C2) solutions running at different current densities for 24 hours was detected.

[0097] Anionic impurity analysis: Ion chromatography for Cl in C1 and C2 - and SO4 2- The test results are shown in Table 4.

[0098] Table 4 Test Results

[0099] Reference Figure 15 Cl of C1 and C2 under different current densities - Concentration comparison, Cl of C2 / C1 - The concentration ratios are all greater than 3, indicating that Cl - It tends to accumulate in the common product chamber C2, which aligns with the design for ion migration direction; however, 0.23–0.49 mol / L Cl still exists in C1. - Residue. SO4 2- The concentration in C1 is approximately 0.02~0.03 mol / L, mainly due to trace transmembrane leakage of Na2SO4 from the electrode liquid chamber.

[0100] Based on the product composition determined by charge balance, the charge balance equation for the C1 solution is: Na + +2Ca 2+ +H + =OH - +Cl - +2SO4 2- +HCO3 - +2CO3 2- ; H under high pH conditions of C1 + Negligible; the main anion detected is OH-. - (0.2~1.3mol / L), Cl - With SO4 2- The impurity anions (total 0.05~0.5 mol / L) are present. Based on charge conservation, the main cation in the solution is Na+. + Its main source is NaCl in the paired ion feed chamber that migrates directionally into Cl through the cation exchange membrane, and reacts with OH- that migrates through the anion exchange membrane. - The compounds combine to form NaOH. Therefore, it can be inferred that the Cl product is mainly composed of NaOH, while also containing a small amount of Cl. - SO4 2- Impurities, etc.

[0101] Ca 2+ Thermodynamic constraints of leakage C1 high OH - Environment's influence on Ca 2+ Transmembrane leakage constitutes a thermodynamic limitation. If Ca 2+ The concentration of dissolved substances leaking from F1 to C1 is constrained by the dissolution equilibrium of Ca(OH)2: Ksp(Ca(OH)2) = [Ca 2+ ][OH - ] 2≈5.5×10 -6 (The concentration scale is a theoretical estimate. The activity coefficient may introduce deviations under high ionic strength. The actual value should be based on direct detection.) When OH in C1 - When the concentration reaches 1.0 mol / L, the dissolved Ca 2+ The theoretical upper limit is approximately 5.5 × 10⁻⁶. -6 mol / L (approximately 0.22 mg / L).

[0102] Reference Figure 16 The measured OH values ​​at various time points of C1 are displayed. - Concentration corresponding to dissolved Ca 2+ Upper limit of solubility. This estimate applies only to dissolved Ca. 2+ The possibility of an increase in total calcium due to mechanical entrainment of Ca(OH)2 or CaCO3 particles cannot be ruled out. The total calcium content still needs to be further verified by methods such as EDTA complexometric titration, ICP-OES or AAS.

[0103] Test Example 11 This test example uses MgO instead of CaO as a low-solidity solid raw material to verify the versatility of the alkaline earth metal oxide / hydroxide system in the method of this invention. The test conditions are shown in Table 5.

[0104] Table 5 Test Conditions

[0105] MgO hydrates rapidly into Mg(OH)2 after being added to water, forming a low-solidity solid-liquid slurry, which continuously supplies OH to chamber F1. - Theoretical OH content of 5g MgO - The equivalent capacity is 0.248 mol-eq, and the theoretical charge equivalent of the stack within 240 min is 0.191 mol-eq, with a capacity margin of approximately 1.30 times.

[0106] Reference Figure 17 The conductivity of chamber F1 remained between 0.06 and 0.08 mS / cm throughout, consistent with the low solubility supply characteristics of Mg(OH)2; the bulk concentration was low, but the solid continuously dissolved to replenish it. The conductivity of chamber C1 increased from an initial 2.3 mS / cm to 92.0 mS / cm, and that of chamber C2 increased from 2.9 mS / cm to 70.0 mS / cm, indicating continuous accumulation of products on both sides. The conductivity of chamber F2 slowly decreased from 82.8 mS / cm to 73.5 mS / cm, corresponding to the net migration of NaCl to the product chambers on both sides. The conductivity of electrode solution chamber E remained relatively stable at 25.7-26.0 mS / cm.

[0107] Reference Figure 18 Combined with the basicity of C1 products, C1 conductivity and OH- in Table 6 -The concentration increased synchronously. At 240 min, the C1NaOH concentration reached 0.45 M, and the effective solid supply of OH... - The efficiency was 40%. The increase in C1 alkalinity showed an approximately linear relationship with charge input, indicating that the Mg(OH)2 solid-liquid balance could continuously replenish the OH groups consumed by migration. - There was no supply disruption.

[0108] Table 6. Basicity of C1 Products

[0109] Based on the basicity of the C2 product in Table 7, the C2 side H + The terminal concentration was 0.15 M, accounting for 10.7% of the theoretical charge equivalent of the stack. This was mainly contributed by the F1 interface polarization / water dissociation side reaction, indicating a low degree of polarization in the MgO / Mg(OH)₂ system. The solid-state supply pathway significantly affects the OH content in the target product C₁. - The contribution of [the subject / organization] is dominant.

[0110] Table 7. Basicity of C2 Products

[0111] Reference Figure 19 The voltage dropped rapidly from the initial 55.0V (start-up transient) and entered a stable platform of 35-36V after 15 minutes, remaining below the upper limit of 60V throughout the process, indicating stable system operation.

[0112] The product distribution and efficiency indicators at the 240-minute endpoint are shown in Table 8.

[0113] Table 8 Product Distribution and Efficiency Indicators

[0114] The above results indicate that MgO, after being converted to Mg(OH)2 in water, belongs to a low-solidity solid supply system, with a solubility of 100 A / m 2 Stable operation was achieved under conditions of two repeating units and 240 min. The NaOH concentration on the C1 side reached 0.45 M, and Mg was formed on the C2 side. 2+ / Cl - The main co-product system, with side reaction H + The proportion is controllable.

[0115] Combining the results of the CaO-NaCl (Test Example 2-10) and MgO-NaCl (Test Example 11) systems, both of the two different low-solidity solid raw materials (CaO / Ca(OH)2, MgO / Mg(OH)2) can achieve continuous ion supply and target product accumulation in this method, which preliminarily shows that the "solid raw material-dissolution equilibrium-electromigration coupling" mechanism is applicable to different alkaline earth metal oxide and hydroxide systems.

[0116] The embodiments shown in this specification are only used to illustrate the technical solutions of the present invention and are intended to help those skilled in the art understand the principles and advantages of the present invention. They do not constitute a limitation on the scope of protection of the present invention. Although the present invention has been specifically described, those skilled in the art can still make any modifications, equivalent substitutions or other reasonable variations to the implementation methods without departing from the spirit and scope of the present invention. All equivalent technical solutions resulting therefrom should be considered within the scope of protection of this patent.

Claims

1. An electro-driven membrane reaction method based on the coupling of solid-state dissolution equilibrium and electromigration, characterized in that, Includes the following steps: 1) Mix the low-solubility solid raw material containing the target ion with a solvent to form a feeding system that exists at least partially in the form of solid particles, suspensions, slurries or solid-liquid coexistence. 2) The feeding system is introduced into the solid feeding chamber of the electrically driven membrane reactor, and an electrolyte solution containing paired ions is introduced into the paired ion feeding chamber; 3) Apply a DC electric field to selectively migrate and consume target ions near the membrane interface in the solid feed chamber through the ion exchange membrane. The local activity of the corresponding ions in the feed system decreases accordingly, breaking the dissolution equilibrium of the low-solubility solid raw material and inducing the solid raw material to continuously dissolve and release target ions. 4) The migrated target ions recombine with the paired ions from the paired ion feed chamber in the product chamber to generate the target electrolyte product.

2. The electro-driven membrane reaction method based on solid-state dissolution equilibrium and electromigration coupling according to claim 1, characterized in that, In step 1), the low-solidity solid raw material is at least one of alkaline earth metal oxides, alkaline earth metal hydroxides, slightly soluble salts, sparingly soluble salts, mineral raw materials, and industrial by-product solids.

3. The electro-driven membrane reaction method based on solid-state dissolution equilibrium and electromigration coupling according to claim 2, characterized in that, In step 1), the low-solidity solid raw material is an alkaline earth metal oxide; The alkaline earth metal oxide undergoes an in-situ hydration reaction with water in the feeding system to generate alkaline earth metal hydroxide, and the target ion is continuously released through the dissolution equilibrium of the alkaline earth metal hydroxide.

4. The electro-driven membrane reaction method based on solid-state dissolution equilibrium and electromigration coupling according to claim 1, characterized in that, By adjusting at least one of the parameters, namely current density, feed flow rate, particle size, solid content, and compartment volume ratio, the ion release rate of the low-solidity solid raw material is matched with the ion migration and consumption rate under the action of the electric field.

5. An electrically driven membrane reaction apparatus for implementing the electrically driven membrane reaction method as described in any one of claims 1-4, characterized in that, Includes DC power supply, anode, cathode, electrode liquid circulation system, and ion exchange membrane stack; The ion exchange membrane stack is divided by alternating cation exchange membranes and anion exchange membranes to form at least one electrode chamber, at least one low-solubility solid feed chamber, at least one paired ion feed chamber, at least one target product chamber and at least one common product chamber; The low-solubility solids feeding chamber or its circulation pipeline is equipped with a solid particle interception structure to retain undissolved solid particles in the feeding circulation system.

6. The electrically driven membrane reactor according to claim 5, characterized in that, The compartments of the ion exchange membrane stack are arranged as follows: electrode compartment, cation exchange membrane, target product compartment, anion exchange membrane, low-solidity solid feed compartment, cation exchange membrane, common product compartment, anion exchange membrane, paired ion feed compartment, cation exchange membrane, and electrode compartment.

7. The electrically driven membrane reactor according to claim 5, characterized in that, The solid particle trapping structure is at least one of the following: screen, filter, porous baffle, settling zone, hydrocyclone separator, or external solid-liquid separator.

8. The electrically driven membrane reactor according to claim 5, characterized in that, The low-solubility solids feeding chamber adopts a flow channel structure suitable for solid-liquid multiphase flow operation; The flow channel structure is at least one of the following: wide flow channel structure, grid support structure, anti-deposition baffle, high shear circulation flow channel, tangential feeding structure, or turbulence structure.

9. The electrically driven membrane reactor according to claim 5, characterized in that, The circulation volume of the low-solidity solids feeding chamber is greater than the circulation volume of the target product chamber, and the circulation volume ratio of the low-solidity solids feeding chamber to the target product chamber is 2:1 to 100:

1.

10. The application of the electro-driven membrane reaction method according to any one of claims 1-4 in the preparation of strong bases, salt conversion, resource utilization of concentrated brine, conversion of low-solubility mineral raw materials, or resource utilization of industrial by-product solids.

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