Membrane, method and system for separating monovalent anions

Abstract

The invention discloses a membrane, a method and a system for separating monovalent anions, and belongs to the technical field of membranes. The membrane is prepared from a specific polymer and a specific targeting functional carrier; the thickness range of the film is 45-250 [mu] m; the preparation method of the membrane comprises the following steps: carrying out degassing treatment on a mixed solution of the polymer and the targeting functional carrier by adopting an ultrasonic degassing mode, pouring into a mold, and carrying out solvent volatilization to obtain the required targeting separation membrane. The targeted separation membrane is applied to an electrodialysis system to realize separation of different monovalent anions. According to the invention, the separation performance of electrodialysis on monovalent anions can be greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of membrane technology, and in particular relates to a membrane, method and system for separating monovalent anions. Background Art

[0002] At present, membrane technologies are widely used in the treatment of industrial high-salinity wastewater, such as ultrafiltration, nanofiltration, reverse osmosis, and electrodialysis. Among these membrane technologies, only nanofiltration and electrodialysis have the ability to separate ions. Nanofiltration technology, as a membrane technology with selective separation function, can effectively separate monovalent and divalent ions, but this technology cannot distinguish anions and cations well during the separation process. This feature limits the application of nanofiltration in certain fields. At the same time, electrodialysis, as an ion exchange membrane technology, also has a strong ion separation ability. Electrodialysis applies a DC voltage to cause the ions in the solution to migrate under the action of the electric field force, and the ions are separated by the selectivity of the anion and cation exchange membrane. Compared with nanofiltration, electrodialysis has higher selectivity in separating anions and cations, so it has a wider application prospect in certain specific occasions such as industrial high-salinity wastewater resource utilization and seawater desalination concentrated water resource utilization.

[0003] With the continuous development of ion exchange membranes and electrodialysis technology, the separation of anions and cations has gradually expanded to the separation of ions of different valences under the same electrical properties. Patent 202111026258.5 discloses a cross-linked amphoteric ion exchange membrane, which is modified by adding 1-sodium propanesulfonate-3-methylimidazole and N-butylimidazole functionalized polyphenylene ether to form ion clusters of suitable sizes to construct ion transfer channels, and introduce Ui O-66 nanoparticles to reduce the swelling degree of the membrane. The synergistic effect of this material can achieve selective permeation of monovalent anions, while effectively inhibiting the transmission of divalent anions, Cl - and SO4 2- The permeation selectivity can reach 18.9. Patent CN202310081623.5 discloses a method for preparing a monovalent and divalent selective anion membrane that can operate stably in alkaline water treatment. The ether-free polymer PAB is used as a precursor, and the selective separation of monovalent and divalent ions is achieved through the quantitative removal of protons, quaternization and cross-linking. - and SO4 2- The separation coefficient can reach 12.46. Pan et al. used sulfadiazine as a crosslinking agent and added partially quaternized chloromethylated polysulfone to prepare an internally crosslinked monovalent selective ion exchange membrane. The increase in the degree of crosslinking and the introduction of sulfonamide groups reduced the membrane resistance, increased the monovalent selectivity, and reduced the ion exchange capacity. Under the optimal conditions, the modified membrane had a high selectivity for Cl - and SO4 2-The separation coefficient of the system can reach 15.90. Mubita et al. reported an AEM based on quaternized poly(2,6-dimethylphenoxy) containing alkyl side chains. The hydrophobicity of AEMs was adjusted by changing the length of the alkyl chain connected to the charged ammonium group, achieving high selectivity for monovalent and divalent anions and low membrane swelling. - and SO4 2- The selectivity can reach 13.7. Liao et al. blended amino-containing poly(aryl ether sulfone) (PAES-NH2) with 15 wt% sulfonated polysulfone (SPSf) and grafted imidazolium-terminated side alkyl chains on the PAES backbone to prepare a membrane. Under the synergistic effect of the electrostatic repulsion difference of the negatively charged sulfonate group on the ions and the difference in the hydration energy of the ions, Cl - and SO4 2- The permeation selectivity reached 21.8. Li et al. used poly(arylene ether sulfone) anion exchange membrane (AEM) as the substrate, introduced modified metal organic framework (MOF) materials, and constructed a fixed-size channel structure in the body of the membrane material. Through the synergistic effect of these channels and the hydrophobicity difference of poly(arylene ether sulfone) polymers, the transmission efficiency of monovalent ions was significantly improved. The modified PAES-UIO-66-PyrCl - and SO4 2- The ion selectivity can reach 54.26.

[0004] In the process of seawater desalination and wastewater treatment, electrodialysis can effectively separate Cl - and SO4 2- , Na + and Mg 2+ Ions of different valences such as ions of nitrate and nitrate. However, in actual operation, the solution usually contains similar ions of the same electrical properties and valence. For example, chloride ion solutions are often inevitably mixed with nitrate impurities, which has an adverse effect on the subsequent utilization of salt resources. Similarly, in the production process using chloride as raw material, the presence of nitrate ions will have an adverse effect on the purity of the product. For example, lithium chloride products may contain lithium nitrate impurities. At this time, it is particularly important to separate these ions. In addition, in hydrometallurgical processes, a mixed acid of hydrochloric acid and nitric acid or aqua regia is usually used as a metal leaching solution. After the metal is extracted, the acid concentration in these leaching solutions will decrease. At this time, not only can separation technology be used to recover these acids, but also hydrochloric acid and nitric acid concentrates can be obtained. However, chloride ions and nitrate ions are both monovalent ions, and their ionic radii are very close, so it is difficult to separate these two ions with current technology. Hawks et al. used ultra-microporous carbon as an electrode for capacitive deionization (CDI), and obtained narrow pores less than 1 nanometer through moderate activation to selectively remove NO3 from anionic mixtures. - , Cl - / NO3 - The selectivity coefficient of ions is about 6.1±0.4; Sun et al. prepared a polypyrrole membrane electrode (PME) by polymerization of pyrrole (Py) and p-toluenesulfonic acid (pTS), Cl - The high binding energy between PPy / pTS structure makes most of Cl - was effectively intercepted, Cl - / NO3 - The selectivity coefficient of ions reached 6.93. Chinello et al. proposed a PVDF-based anion exchange membrane. PVDF has good hydrophobicity and excellent chemical and physical durability. The purpose of improving ion selectivity is achieved by increasing the PVDF concentration in the membrane. The results show that the membrane Cl prepared when the PVDF content is 50% - / NO3 - The selectivity can reach 2.4. It can be seen that the separation performance between monovalent anions is generally low at present. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the above-mentioned related art at least to a certain extent.

[0006] To this end, the object of the present invention is to provide a membrane, method and system for separating monovalent anions, which can greatly improve the separation performance of electrodialysis for monovalent anions.

[0007] In order to solve the above-mentioned technical problems, the present invention is achieved as follows:

[0008] The embodiment of the present invention provides a membrane for separating monovalent anions, wherein the membrane is prepared by using a specific polymer and a specific targeting functional carrier; the thickness of the membrane ranges from 45 to 250 μm; and the method for preparing the membrane includes:

[0009] The mixed solution of the polymer and the targeting functional carrier is degassed by ultrasonic degassing, and then poured into a mold and the solvent is volatilized to obtain the desired targeting separation membrane.

[0010] In addition, the membrane for separating monovalent anions according to the present invention may also have the following additional technical features:

[0011] In some embodiments, the polymer is one or a mixture of cellulose triacetate, polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene) and polyvinylidene fluoride.

[0012] In some embodiments, the targeting functional carrier is one or a mixture of methyl trioctyl ammonium thiocyanate, methyl trioctyl ammonium nitrate, methyl trioctyl ammonium chloride, methyl trioctyl ammonium bromide, trihexyltetradecyl phosphine chloride, trihexyltetradecyl phosphine bromide, trihexyltetradecyl phosphine nitrate and trihexyltetradecyl phosphine thiocyanate.

[0013] In some embodiments, the solvent in the mixed solution of the polymer and the targeting functional carrier is one or a mixture of several of ethanol, tetrahydrofuran, dichloromethane, chloroform and N,N-dimethylformamide.

[0014] In some of the embodiments, the mass ratio of the polymer to the targeting functional carrier is (0.6-1.5):1.

[0015] The embodiment of the present invention further provides a method for separating monovalent anions, wherein the targeted separation membrane as described in any one of the above items is applied to an electrodialysis system to achieve separation between different monovalent anions.

[0016] In addition, the method for separating monovalent anions according to the present invention may also have the following additional technical features:

[0017] In some embodiments, the electrodialysis system is operated in a circulating reflux mode under constant current conditions, comprising:

[0018] A mixed solution containing different monovalent anions is pumped into the desalination chamber of the electrodialysis system and voltage is applied, so that the monovalent anions move under the action of the electric field. A part of the monovalent anions first pass through the targeted separation membrane and enter the concentration chamber; after running for a period of time, the separation of different monovalent anions is completed.

[0019] In some embodiments, the feed flow rate of the pump is 5-30 L / h, and the current density of the applied electric field is 2-10 mA / cm 2 , the experimental temperature is room temperature.

[0020] The embodiment of the present invention further provides a system for separating monovalent anions, which is used to implement the method for separating monovalent anions as described in any one of the above items;

[0021] The system comprises a cathode chamber, a plurality of desalination chambers, a plurality of concentration chambers and an anode chamber;

[0022] A cathode plate is arranged outside the cathode chamber, and an anode plate is arranged outside the anode chamber, and the anode plate and the cathode plate are respectively connected to the positive and negative electrodes of the power supply; a first cation membrane is arranged between the cathode chamber and the desalination chamber; a targeted separation membrane is arranged between the desalination chamber and the concentration chamber; a second cation membrane is arranged between the concentration chamber and the anode chamber; the desalination chamber and the concentration chamber are arranged as follows:

[0023] A desalination chamber and a concentration chamber form a group, and several groups are arranged in succession, and a first cation membrane or a second cation membrane is arranged between the concentration chamber of each group and the desalination chamber of the next group; or,

[0024] A plurality of concentrating chambers are arranged in succession behind a desalination chamber, and a targeted separation membrane is arranged between the desalination chamber and an adjacent concentrating chamber and between any two adjacent concentrating chambers.

[0025] In addition, the system for separating monovalent anions according to the present invention may also have the following additional technical features:

[0026] In some embodiments, a plurality of first repeating units are provided between the cathode chamber and the desalination chamber; a plurality of second repeating units are provided between the concentration chamber and the anode chamber; or,

[0027] A plurality of third repeating units are arranged between the cathode plate and the first cation membrane; and a plurality of fourth repeating units are arranged between the second cation membrane and the anode plate.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] In the embodiment of the present invention, the method for separating monovalent anions provided can achieve a separation factor of up to 1162.40 for chloride ions and nitrate ions;

[0030] In the embodiment of the present invention, the method for separating monovalent anions provided can improve the purity of chloride ions in a mixed solution of chloride ions and nitrate ions from about 93% to 99.69%, and the purity of nitrate ions can also be increased to 92.94% accordingly;

[0031] In the embodiments of the present invention, the method for separating monovalent anions provided can not only effectively separate sodium chloride from sodium nitrate, lithium chloride from lithium nitrate, and hydrochloric acid from nitric acid, but is also effective for separating other monovalent anions (such as thiocyanate ions, iodide ions, bromide ions, fluoride ions, dihydrogen phosphate ions, etc.).

[0032] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A configuration diagram of a targeted separation membrane coupled electrodialysis disclosed in one embodiment of the present invention;

[0034] Figure 2 The different targeted separation membranes disclosed in Examples 4-6 of the present invention separate Cl - and NO3 -When the Cl - and NO3 - Concentration ratio versus time curve;

[0035] Figure 3 The targeted separation membrane prepared in Example 1 is used to separate Cl according to Examples 7-9 of the present invention. - and NO3 - When the Cl - and NO3 - Concentration ratio versus time curve;

[0036] Figure 4 The targeted separation membrane prepared in Example 1 is used to separate Cl in a tandem configuration as disclosed in Example 10 of the present invention. - and NO3 - When the Cl - and NO3 - Concentration ratio versus time curve;

[0037] Figure 5 The targeted separation membrane prepared in Example 1 is used to separate Cl according to Example 11 of the present invention. - and NO3 - When the Cl - and NO3 - Concentration ratio versus time curve;

[0038] Figure 6 The process configuration of separating Cl by two-stage stacking of the targeted separation membrane prepared in Example 1 disclosed in Example 12 of the present invention is as follows: - and NO3 - When the Cl - and NO3 - Concentration ratio versus time curve;

[0039] Figure 7 The process configuration of separating Cl in a three-stage stack of the targeted separation membrane prepared in Example 1 disclosed in Example 13 of the present invention is as follows: - and NO3 - When the Cl - and NO3 - Concentration ratio versus time curve;

[0040] Figure 8 A graph showing the change in the concentration ratio of monovalent anions in the desalination chamber over time when using a targeted separation membrane to separate different mixed monovalent anions as disclosed in Examples 14-19 of the present invention;

[0041] Fig. 9 The different commercial membrane separation Cl disclosed in Comparative Examples 1-4 of the present invention- and NO3 - When the Cl - and NO3 - Concentration ratio versus time.

[0042] Description of reference numerals:

[0043] 1- cathode plate, 2- cathode chamber electrode liquid, 3- first commercial cation membrane, 4- desalination chamber, 5- targeted separation membrane, 6- concentration chamber, 7- second commercial cation membrane, 8- anode chamber electrode liquid, 9- anode plate. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The embodiments of the present invention are described in detail below through specific embodiments and application scenarios in conjunction with the accompanying drawings.

[0046] The existing common ion exchange membrane can only separate anions and cations, and the monovalent and divalent selective ion exchange membrane can separate monovalent and divalent ions, anions such as chloride ions and sulfate, but the separation efficiency for the same monovalent anions such as chloride ions and nitrate is low. In order to overcome the defects of the above-mentioned prior art for the low separation performance between monovalent anions, the present invention proposes a preparation technology for a targeted separation membrane for separation between monovalent anions, and applies the targeted separation membrane to the electrodialysis separation of monovalent anions, and utilizes the selectivity of the freely movable carrier in the membrane, hydrogen bond network, pore size screening, electrostatic repulsion, surface hydrophobicity and Hofmeister effect to achieve efficient separation between monovalent anions. In addition, by innovatively constructing the configuration of the targeted separation membrane in the electrodialysis module, the separation performance of electrodialysis for monovalent anions is further improved.

[0047] The present invention provides a carrier-promoted targeted separation membrane, which optimizes the structure and separation performance of the polymer material membrane by precisely controlling key parameters such as the type, ratio, film-forming reaction time, temperature, and humidity of the polymer and the carrier, thereby creating a targeted separation membrane with good selectivity for specific ions, higher mass transfer efficiency, and high recovery purity.

[0048] The targeted functional carrier in the targeted separation membrane prepared by the present invention is not directly combined with the polymer main chain structure through chemical bonding. The functional carrier utilizes the relatively free movement in the pores between polymer molecules to improve the transmission efficiency of ions. At the same time, the functional carrier can provide selectivity through fixed point hopping, steric hindrance and Donnan effect, and preferentially pass specific ions.

[0049] The polymer of the prepared targeted separation membrane has a strong and tight binding force with the functional carrier and has excellent mechanical properties. Some polymer materials also have good resistance to strong acids and alkalis, good resistance to organic pollution and high stability, and can be used repeatedly, greatly improving its practical value and economic benefits.

[0050] Preparation of targeted separation membrane coupled with electrodialysis for Cl - and NO3 - It has excellent separation performance, which cannot be achieved by ordinary ion exchange membranes currently on the market.

[0051] In addition, the present invention can further improve the separation factor and ion purity by optimizing the electrodialysis configuration, utilizing the series process configuration of multi-stage selective electrodialysis repeating units and the multi-stage stacking process configuration of functional targeted separation membranes.

[0052] The method for separating monovalent anions provided by the present invention comprises the following steps:

[0053] Step 1: dissolving a certain amount and a certain proportion of polymer and targeting functional carrier into a certain amount of organic solvent to obtain a mixed solution.

[0054] The polymer is one or a mixture of cellulose triacetate (CTA), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), polyvinylidene fluoride (PVC).

[0055] The targeting functional carrier is methyl trioctyl ammonium thiocyanate (C 25 H 54 N-SCN), methyl trioctyl ammonium nitrate (C 25 H 54 N-NO3), methyl trioctyl ammonium chloride (C 25 H 54 N-Cl), methyl trioctyl ammonium bromide (C 25 H 54 N-Br), trihexyltetradecylphosphine chloride (C 32 H 68 P-Cl), trihexyltetradecylphosphonium bromide (C 32 H 68 P-Br), trihexyltetradecylphosphine nitrate (C 32 H68 P-NO3), trihexyl tetradecyl phosphine thiocyanate (C 32 H 68 P-SCN) and so on.

[0056] The organic solvent is one or more of ethanol, tetrahydrofuran, dichloromethane, chloroform, and N,N-dimethylformamide.

[0057] The mass ratio of polymer to targeting functional carrier is (0.6-1.5):1.

[0058] The mass ratio of the total mass of the polymer and the targeting functional carrier to the solvent is (0.05-0.4):1.

[0059] Step 2: Stir the obtained mixed solution at a certain temperature to mix the solutions into a uniform solution.

[0060] The stirring temperature is 25-60°C, the humidity during stirring is 30-40%, the stirring speed is 300-500rpm / min, and the stirring time is 2-12h.

[0061] Step 3: Degas the prepared membrane liquid by ultrasonication for 10-30 min to obtain a uniform membrane liquid.

[0062] Step 4: Pour the degassed membrane liquid into the mold, and wait for the solvent to evaporate slowly to form a membrane.

[0063] The thickness of the targeted separation membrane can be controlled by the amount of membrane liquid poured into the mold, and the thickness of the finally prepared membrane material is 45-250 μm.

[0064] Step 5: Immerse the obtained membrane in deionized water to obtain a targeted separation membrane.

[0065] The present invention conducts a performance test on the prepared targeted separation membrane, and separates monovalent anions in the electrodialysis separation and concentration technology process. The electrodialysis separation and concentration system includes a cathode plate, an anode plate, a membrane stack, a DC power supply and a peristaltic pump; the membrane stack includes two cation exchange membranes and a targeted separation membrane, and the cathode plate, the cation exchange membrane, the targeted separation membrane, the cation exchange membrane and the anode plate are sequentially spaced into a cathode chamber, a desalination chamber, a concentration chamber and an anode chamber.

[0066] The electrodialysis separation and concentration system operates in a cyclic reflux mode under constant pressure and constant current conditions. Specifically, a mixed solution containing different monovalent anions, such as a mixed solution of chloride ions and nitrate ions, is pumped into the desalination chamber. Under the action of the electric field, the nitrate ions in the desalination chamber first pass through the targeted separation membrane into the concentration chamber, and after a period of time, the separation of nitrates and the purification and recovery of chlorides are completed.

[0067] The feed flow rate of the desalination chamber, concentration chamber, cathode chamber and anode chamber of the electrodialysis separation and concentration system is 5-30L / h, and the current density of the applied electric field is 2-10mA / cm 2 , specifically: water flow rate is 10L / h, current density is 4mA / cm 2 The experimental temperature is room temperature and the experimental time is 10-48h.

[0068] The volume of the solution pumped into the desalination chamber is 250 mL; the volume of the solution pumped into the concentration chamber is 250 mL; the cathode chamber and the anode chamber are arranged in series, and the total volume of the solution pumped into the two is 250 mL, and peristaltic pumps are used for solution circulation.

[0069] The volume of each chamber in the membrane assembly of the electrodialysis separation and concentration system is 20 cm 3 , the effective membrane area is 20cm 2 .

[0070] The targeted functional carrier in the targeted separation membrane prepared by the present invention is not directly combined with the polymer main chain structure through chemical bonds. The functional carrier utilizes the relatively free movement in the pores between polymer molecules to improve the transmission efficiency of ions; the functional carrier can provide selectivity through fixed point hopping, steric hindrance and Donnan effect, and preferentially pass specific ions.

[0071] Embodiment 1:

[0072] The steps for preparing the targeted separation membrane are as follows:

[0073] Preparation of membrane solution: Weigh 0.44g polymer poly(vinylidene fluoride-co-hexafluoropropylene) and 0.66g targeting functional carrier tri-n-hexyltetradecylphosphine chloride (Cyphos IL 101), add a certain amount of organic solvent, stir on a magnetic stirrer at 55°C until dissolved, and then perform ultrasonic degassing to obtain a uniform and transparent membrane solution.

[0074] Preparation of membrane: Pour the membrane liquid into a film-forming mold that has been leveled and placed horizontally. The organic solvent evaporates slowly at room temperature. After the evaporation is completed, the prepared membrane is placed in deionized water, peeled off from the mold and stored at low temperature.

[0075] Embodiment 2:

[0076] The preparation of the membrane solution and the preparation of the membrane were carried out in the same manner as in Example 1, except that the targeting functional carrier used was methyl tri-n-octyl ammonium chloride (Aliquat 336[Cl]).

[0077] Embodiment 3:

[0078] The preparation of the membrane liquid and the preparation of the membrane adopt the same preparation method as in Example 1, except that the targeting functional carrier used is a methyl tri-n-octyl ammonium chloride modified material (Aliquat 336[NO3]).

[0079] Embodiment 4:

[0080] Using the targeted separation membrane prepared in Example 1, Cl - and NO3 - The separation performance test was carried out using an electrodialysis test device. The electrodialysis configuration diagram is shown in Figure 1 As shown, it includes a cathode chamber 2, a desalination chamber 4, a concentration chamber 6 and an anode chamber 8; a cathode plate 1 is arranged on the outside of the cathode chamber 2, and an anode plate 9 is arranged on the outside of the anode chamber 8, and the anode plate 9 and the cathode plate 1 are respectively connected to the positive and negative poles of the power supply; a first cation membrane 3 is arranged between the cathode chamber 2 and the desalination chamber 4; a targeted separation membrane 5 is arranged between the desalination chamber 4 and the concentration chamber 6; and a second cation membrane 7 is arranged between the concentration chamber 6 and the anode chamber 8.

[0081] 250mL of 0.3mol / L sodium chloride solution and 0.3mol / L sodium nitrate solution were circulated into the desalination chamber by a peristaltic pump to simulate high-concentration saline wastewater; 0.1mol / L sodium sulfate solution was pumped into the concentration chamber as a conductive electrolyte for circulation; 0.3mol / L sodium sulfate solution was pumped into the cathode chamber and the anode chamber by a peristaltic pump, and circulated through the external pipeline. The electrode chambers on both sides were connected in series through the external pipeline. The DC power supply was in constant current mode, and the current density was 4mA / cm 2 , the desalination chamber was sampled at different time intervals, and the ion concentration was tested by ion chromatography.

[0082] Separation factor Right now:

[0083]

[0084] in, is the molar concentration of nitrate ions (mol L -1 ), It is Cl - The molar concentration (mol L -1 ), It is Cl in the feed liquid or concentrate - and NO3 - Ion concentration ratio, S is the concentrate, F is the feed solution, and t(h) is the transmission time.

[0085] Separation purity Right now:

[0086]

[0087] in, is the NO3 in the feed liquid or concentrate at the tth hour - or Cl - Mass (g), m f / s is the mass of all ions in the feed solution or concentrate (g);

[0088] Test results such as Figure 2 As shown in the figure, (a) is PVDF-HFP / Cyphos IL 101 membrane, (b) is PVDF-HFP / Aliquant 336[Cl] membrane; (c) is PVDF-HFP / Aliquant 336[NO3] membrane. It can be seen that the purity of chloride ions in the desalination chamber is 98.3% in 36h, the purity of nitrate ions in the concentration chamber is 91.8%, and the separation factor is Can reach 650.

[0089] Embodiment 5:

[0090] Example 5: Using the targeted separation membrane prepared in Example 2 to perform Cl - and NO3 - The separation performance test of the electrodialysis test configuration and conditions are the same as those in Example 4. The test results are shown in Figure 2 As shown, the 36h separation factor Reached 100.4.

[0091] Embodiment 6:

[0092] Example 6: Using the targeted separation membrane prepared in Example 3 to perform Cl - and NO3 - Separation performance test, electrodialysis test configuration and conditions are the same as in Example 4. The test results are as follows Figure 2 As shown, the 36h separation factor Reached 83.7.

[0093] Embodiment 7:

[0094] The same targeted separation membrane and electrodialysis test configuration and conditions as in Example 4 were used, except that the feed solution concentration pumped into the desalination chamber was different, and 250 mL of a mixed solution of 0.51 mol / L sodium chloride and 0.02 mol / L sodium nitrate was pumped into the desalination chamber. The test results are shown in Figure 3 As shown in the figure, the purity of chloride ions in the desalination chamber increased from about 93% to 98.48%, and the separation factor was It can reach 142.89.

[0095] Embodiment 8:

[0096] The same targeted separation membrane and electrodialysis test configuration and conditions as in Example 4 were used, except that the type of feed liquid pumped into the desalination chamber was different, and 250 mL of a mixed solution of 0.51 mol / L lithium chloride and 0.02 mol / L lithium nitrate was pumped into the desalination chamber. The test results are shown in Figure 2. Figure 3 As shown in the figure, the purity of chloride ions in the desalination chamber increased from about 93% to 99.34%, and the separation factor was Reached 80.87.

[0097] Embodiment 9:

[0098] The same targeted separation membrane and electrodialysis test configuration and conditions as in Example 4 were used, except that the type of feed liquid pumped into the desalination chamber was different, and 250 mL of a mixed solution of 0.51 mol / L hydrochloric acid and 0.02 mol / L nitric acid was pumped into the desalination chamber. The test results are shown in Figure 3 As shown in the figure, the purity of chloride ions in the desalination chamber increased from about 93% to 98.88%, and the separation factor was Reached 46.24.

[0099] Embodiment 10:

[0100] Example 10 Using an improved electrodialysis configuration to carry out Cl - and NO3 - The separation performance test was conducted using the same targeted separation membrane, electrodialysis test conditions and feed solution as in Example 7, except that a set of repeated electrodialysis units were superimposed and the solutions in the desalination compartment and the concentration compartment were connected in series.

[0101] The improved electrodialysis configuration in this embodiment is Figure 1 The improvement is made on the basis of the electrodialysis configuration, in which several groups of repeating units n are added in series behind the targeted separation membrane 5 (the repeating unit n is the first commercial cation membrane 3, the desalination chamber 4, the targeted separation membrane 5, and the concentration chamber 6), and the ion transmission rate is greatly improved through the series process of superimposing the repeating units in series.

[0102] The results of the test using the above electrodialysis configuration are as follows: Figure 4 As shown, this embodiment uses the targeted ion exchange membrane prepared in Example 1 to separate Cl in a series process with a set of selective electrodialysis repeating units superimposed. - and When the Cl - and The concentration ratio changes with time. The purity of chloride ions in the desalination chamber increases from about 93% to 99.94%. The separation coefficient of 8h Reaching 302.23, the time required for 80% nitrate transmission is shortened to half of the normal configuration.

[0103] Embodiment 11:

[0104] The same targeted separation membrane and electrodialysis test configuration and conditions as in Example 7 were used, except that 250 mL of 0.02 mol / L sodium nitrate solution was pumped into the concentration chamber. Figure 5 As shown, the targeted separation membrane prepared in Example 1 is used to separate Cl - and NO3 - The Cl in the desalination chamber - and NO3 - The concentration ratio curve over time shows that the purity of chloride ions in the desalination chamber increased from about 93% to 99.14%, and the purity of nitrate ions in the concentration chamber reached 52.64%. The 8h separation factor Reached 60.43.

[0105] Embodiment 12:

[0106] Example 12: Using an improved electrodialysis configuration to perform Cl - and NO3 - The separation performance test was conducted using the same targeted separation membrane and electrodialysis test conditions as in Example 7, with the difference being that two concentration chambers were used in the process configuration of multi-stage stacking of targeted separation membranes for the experiment, into which 250 mL of 0.02 mol / L sodium nitrate solution was pumped.

[0107] In this embodiment, the electrodialysis configuration is Figure 1 The improvement is that multiple sets of targeted separation membrane stacking units n (stacking unit n is targeted separation membrane 5 and concentration chamber 6) are arranged immediately behind the concentration chamber 6. The multiple sets of targeted separation membranes stacked in this configuration can achieve Cl - and NO3 - Further separation and purification of ions.

[0108] The results of the test using the above improved electrodialysis configuration are as follows Figure 6 As shown, the targeted separation membrane prepared in Example 1 is used to stack a group of targeted separation membrane units to obtain a two-stage concentration chamber process configuration for separating Cl- and The Cl- and The concentration ratio changes with time. The purity of chloride ions in the desalination chamber increases from about 93% to 99.27%. The nitrate ions in the concentration chamber are enriched and the purity increases from the initial configuration of 52.64% to 90.87%. The 8h separation coefficient Reached 496.16.

[0109] Embodiment 13:

[0110] Example 13 also uses the improved electrodialysis configuration to carry out Cl - and NO3 - The separation performance test was conducted using the same targeted separation membrane and electrodialysis test conditions as in Example 7, with the difference being that three concentration chambers were used in the process configuration of multi-stage stacking of the targeted separation membrane, into which 250 mL of 0.02 mol / L sodium nitrate solution was pumped.

[0111] In this embodiment, the electrodialysis configuration is Figure 1 The improvement is that multiple sets of targeted separation membrane stacking units n (stacking unit n is targeted separation membrane 5 and concentration chamber 6) are continuously arranged behind the concentration chamber 6. The multiple sets of targeted separation membranes stacked in this configuration can achieve Cl - and NO3 - Further separation and purification of ions.

[0112] The results of the test using the above improved electrodialysis configuration are as follows Figure 7 As shown, the targeted separation membrane prepared in Example 1 is used to stack two sets of targeted separation membrane units to obtain a three-stage concentration chamber process configuration for separation of Cl - and The Cl in the desalination chamber - and The concentration ratio curve over time shows that the purity of chloride ions in the desalination chamber increased from about 93% to 99.69%, and the nitrate ions in the concentration chamber were enriched and the purity increased from 52.64% in the initial configuration to 92.94%. The 8h separation coefficient It can reach 1162.40.

[0113] Embodiment 14:

[0114] The same targeted separation membrane and electrodialysis test configuration and conditions as in Example 4 were used, except that the type of feed liquid pumped into the desalination chamber was different, and 250 mL of a mixed solution of 0.1 mol / L sodium fluoride and 0.1 mol / L sodium chloride was pumped into the desalination chamber. The test results are shown in Figure 8 As shown in (a), the 8h separation factor Reached 89.27.

[0115] Embodiment 15:

[0116] The same targeted separation membrane and electrodialysis test configuration and conditions as in Example 4 were used, except that the type of feed liquid pumped into the desalination chamber was different, and 250 mL of a mixed solution of 0.1 mol / L sodium chloride and 0.1 mol / L sodium bromide was pumped into the desalination chamber. The test results are shown in Figure 2. Figure 8 As shown in (b), the 8h separation factor Reached 7.95.

[0117] Embodiment 16:

[0118] The same targeted separation membrane and electrodialysis test configuration and conditions as in Example 4 were used, except that the type of feed liquid pumped into the desalination chamber was different, and 250 mL of a mixed solution of 0.1 mol / L sodium chloride and 0.1 mol / L sodium iodide was pumped into the desalination chamber. The test results are shown in Figure 8 As shown in (c), the 8h separation factor Reached 62.66.

[0119] Embodiment 17:

[0120] The same targeted separation membrane and electrodialysis test configuration and conditions as in Example 4 were used, except that the type of feed liquid pumped into the desalination chamber was different, and 250 mL of a mixed solution of 0.1 mol / L sodium bromide and 0.1 mol / L sodium fluoride was pumped into the desalination chamber. The test results are shown in Figure 2. Figure 8 As shown in (d), the 8h separation factor Reached 327.99.

[0121] Embodiment 18:

[0122] The same targeted separation membrane and electrodialysis test configuration and conditions as in Example 4 were used, except that the type of feed liquid pumped into the desalination chamber was different, and 250 mL of a mixed solution of 0.1 mol / L sodium thiocyanate and 0.1 mol / L sodium bromide was pumped into the desalination chamber. The test results are shown in Figure 2. Figure 8 As shown in (e), the 8h separation factor Reached 85.47.

[0123] Embodiment 19:

[0124] The same targeted separation membrane and electrodialysis test configuration and conditions as in Example 4 were used, except that the type of feed liquid pumped into the desalination chamber was different, and 250 mL of a mixed solution of 0.1 mol / L sodium iodide and 0.1 mol / L sodium nitrate was pumped into the desalination chamber. The test results are shown in Figure 8 As shown in (f), the 8h separation factor Reached 86.80.

[0125] For comparison, four commercial ion exchange membranes were selected: monovalent and divalent anion membrane (ACS) and standard anion membrane (AMX) produced by ASTOM Co., Ltd. of Japan, and monovalent and divalent anion selective membrane (ASVN) and standard anion selective membrane (AMVN) produced by Asahi Glass Co., Ltd. of Japan for Cl - and NO3 -Separation performance test.

[0126] Comparative Example 1:

[0127] The same electrodialysis test conditions as in Example 4 were used, except that the targeted separation membrane used was replaced with a monovalent and divalent anion membrane (ACS) produced by ASTOM Co., Ltd. of Japan. The test results are shown in Fig. 9 As shown in (a), the 48h separation factor It is 28.68.

[0128] Comparative Example 2:

[0129] The same electrodialysis test conditions as in Example 4 were used, except that the targeted separation membrane used was replaced with a standard anion membrane (AMX) produced by ASTOM Co., Ltd. of Japan. The test results are shown in FIG. Fig. 9 As shown in (b), the 48h separation factor is 2.32.

[0130] Comparative Example 3:

[0131] The same electrodialysis test conditions as in Example 4 were used, except that the targeted separation membrane used was replaced with a monovalent and divalent anion selective membrane (ASVN) produced by Asahi Glass Co., Ltd. (ACG). Fig. 9 As shown in (c), the 7h separation factor is 2.51.

[0132] Comparative Example 4:

[0133] The same electrodialysis test conditions as in Example 4 were used, except that the targeted separation membrane used was replaced with a standard anion selective membrane (AMVN) produced by Asahi Glass Co., Ltd. (ACG). Fig. 9 As shown in (d), the 7h separation factor is 1.33.

[0134] Comparison of the embodiments and comparative examples shows that in Cl - and Under the condition of mixed feed solution with concentration ratio of 1:1, Example Cl of the present invention - and The separation efficiency of commercial membrane separation Cl - and 22.66-488.72 times of that in the case of a mixed feed solution of 0.51 mol / L sodium chloride and 0.02 mol / L sodium nitrate, Cl - and A separation factor of 142.89 can be achieved, desalination chamber Cl -The purity of Cl can reach 98.48%; and with the optimization of the configuration process, the Cl - The purity can reach 99.69%, and the ion separation coefficient It can reach 1162.40; other monovalent anions can also achieve good separation effects.

[0135] Parts of the present invention that are not described in detail may refer to the prior art or are known to those skilled in the art.

[0136] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A membrane for separating monovalent anions, characterized in that The membrane is prepared by using a specific polymer and a specific targeting functional carrier; the thickness of the membrane ranges from 45 to 250 μm; The method for preparing the film comprises: The mixed solution of the polymer and the targeting functional carrier is degassed by ultrasonic degassing, and then poured into a mold and the solvent is volatilized to obtain the desired targeting separation membrane.

2. The membrane for separating monovalent anions according to claim 1, characterized in that The polymer is one or a mixture of triacetyl cellulose, polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene) and polyvinylidene fluoride.

3. The membrane for separating monovalent anions according to claim 1, characterized in that The targeting functional carrier is one or a mixture of methyl trioctyl ammonium thiocyanate, methyl trioctyl ammonium nitrate, methyl trioctyl ammonium chloride, methyl trioctyl ammonium bromide, trihexyltetradecyl phosphonium chloride, trihexyltetradecyl phosphonium bromide, trihexyltetradecyl phosphonium nitrate and trihexyltetradecyl phosphonium thiocyanate.

4. The membrane for separating monovalent anions according to claim 1, characterized in that The solvent in the mixed solution of the polymer and the targeting functional carrier is one or a mixture of several of ethanol, tetrahydrofuran, dichloromethane, chloroform and N,N-dimethylformamide.

5. The membrane for separating monovalent anions according to claim 1, characterized in that The mass ratio of the polymer to the targeting functional carrier is (0.6-1.5):

1.

6. A method for separating monovalent anions, characterized in that: The targeted separation membrane according to any one of claims 1 to 5 is applied to an electrodialysis system to achieve separation of different monovalent anions.

7. The method for separating monovalent anions according to claim 6, characterized in that: The electrodialysis system is operated in a circulating reflux mode under constant current conditions, comprising: A mixed solution containing different monovalent anions is pumped into the desalination chamber of the electrodialysis system and voltage is applied, so that the monovalent anions move under the action of the electric field. A part of the monovalent anions first pass through the targeted separation membrane and enter the concentration chamber; after running for a period of time, the separation of different monovalent anions is completed.

8. The method for separating monovalent anions according to claim 6, characterized in that: The feed flow rate of the pump is 5-30L / h, and the current density of the applied electric field is 2-10mA / cm 2 , the experimental temperature is room temperature.

9. A system for separating monovalent anions, characterized in that: Contents for realizing the method for separating monovalent anions according to any one of claims 6 to 8; The system comprises a cathode chamber, a plurality of desalination chambers, a plurality of concentration chambers and an anode chamber; A cathode plate is arranged outside the cathode chamber, and an anode plate is arranged outside the anode chamber, and the anode plate and the cathode plate are respectively connected to the positive and negative electrodes of the power supply; a first cation membrane is arranged between the cathode chamber and the desalination chamber; a targeted separation membrane is arranged between the desalination chamber and the concentration chamber; a second cation membrane is arranged between the concentration chamber and the anode chamber; the desalination chamber and the concentration chamber are arranged as follows: A desalination chamber and a concentration chamber form a group, and several groups are arranged in succession, and a first cation membrane or a second cation membrane is arranged between the concentration chamber of each group and the desalination chamber of the next group; or, A plurality of concentrating chambers are arranged in succession behind a desalination chamber, and a targeted separation membrane is arranged between the desalination chamber and an adjacent concentrating chamber and between any two adjacent concentrating chambers.

10. The system for separating monovalent anions according to claim 9, characterized in that: A plurality of first repeating units are arranged between the cathode chamber and the desalination chamber; a plurality of second repeating units are arranged between the concentration chamber and the anode chamber; or, A plurality of third repeating units are arranged between the cathode plate and the first cation membrane; and a plurality of fourth repeating units are arranged between the second cation membrane and the anode plate.

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