Method for producing chlorine-removing electrode, electrochemical chlorine-removing device and method

Abstract

The present application relates to a kind of preparation method of chlorine removal electrode, electrochemical chlorine removal device and method, belong to water treatment technical field.Chlorine removal electrode is used for electrochemical adsorption removal of chlorine ion in water, its preparation method includes: preparation of chlorine removal nanomaterial, chlorine removal nanomaterial is the variable valence metal hydroxide or variable valence metal oxide of layered structure;Chlorine removal nanomaterial is mixed with conductive agent, adhesive, to obtain electrode material;Electrode material is coated on conductive substrate, to obtain chlorine removal electrode;Wherein, chlorine removal nanomaterial can make the chlorine ion in water electrochemical adsorption in chlorine removal electrode under the action of electric field, to remove the chlorine ion in water.Layered structure variable valence metal hydroxide or variable valence metal oxide is used as electrode material of chlorine removal electrode, not only low in cost, and the adsorption amount of chlorine ion is large, can effectively remove the chlorine ion in water.Chlorine ion is embedded and saturated after adsorption in chlorine removal electrode, can be regenerated, to realize recycling.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, and in particular to a preparation method of a chlorine removal electrode, an electrochemical chlorine removal device and method. BACKGROUND

[0002] Recycling of reclaimed water can alleviate the problem of water resource shortage. However, there are a large amount of chloride ions in domestic sewage and industrial wastewater, which leads to harmful effects such as crop yield reduction, soil salinization, and equipment corrosion when the reclaimed water obtained by recycling thereof is used for agricultural irrigation and industrial use. Therefore, it is crucial to remove chloride ions from reclaimed water.

[0003] At present, due to good solubility, small ionic radius, low charge quantity, and limited biological availability of chloride ions, the secondary treatment and conventional tertiary treatment technology (coagulation, biological filtration, microfiltration, etc.) in the process of sewage treatment cannot effectively remove chloride ions. In addition, some commonly used methods for removing chloride ions have disadvantages, for example, the reverse osmosis device has high cost and poor economic benefit; the ion exchange agent commonly used in ion exchange method is ion exchange resin, which has small adsorption capacity and weak regeneration capacity. SUMMARY

[0004] In view of the above analysis, the embodiments of the present application aim to provide a preparation method of a chlorine removal electrode, an electrochemical chlorine removal device and method, to solve at least one of the problems of the prior art, such as difficulty in effectively removing chloride ions, low chloride ion removal rate, and high cost.

[0005] In one aspect, the embodiments of the present application provide a preparation method of a chlorine removal electrode. The chlorine removal electrode is used for electrochemical adsorption to remove chloride ions in water, and the preparation method comprises: preparing a chlorine removal nanomaterial, the chlorine removal nanomaterial being a variable valence metal hydroxide or a variable valence metal oxide with a layered structure; mixing the chlorine removal nanomaterial with a conductive agent and a bonding agent to obtain an electrode material; and coating the electrode material on a conductive substrate to obtain the chlorine removal electrode; wherein the chlorine removal nanomaterial can electrochemically adsorb chloride ions in water on the chlorine removal electrode under the action of an electric field, so as to remove the chloride ions in water.

[0006] Further, the chlorine removal nanomaterial comprises: a first metal ion and a second metal ion; wherein the first metal ion comprises at least one of Ni 2+ , Co 2+ , Ti 2+ , Cr 2+ , In 2+ , Zn 2+ , and Mg 2+ ; and the second metal ion comprises Fe 3+ , Mn 3+ , Ti 3 + , Cr3+ at least one of Al 3+ at least one of In 3+ at least one of Co 3+ and Ti 4+ at least one of Al, In, Co and Ti.

[0007] Further, the preparation of the chlorine-removing nanomaterials comprises: mixing metal salts corresponding to the first metal ions and the second metal ions to prepare a salt solution; mixing the salt solution with an alkali solution, and performing a crystallization reaction or a hydrothermal reaction to obtain a variable-valence metal hydroxide.

[0008] Further, the preparation of the chlorine-removing nanomaterials further comprises: calcining the variable-valence metal hydroxide to obtain a variable-valence metal oxide.

[0009] In another aspect, the embodiments of the present application also provide an electrochemical chlorine-removing device for removing chlorine ions in water, which comprises: a reaction chamber for containing a chlorine-containing solution to be treated; an anode and a cathode, the anode being a chlorine-removing electrode prepared according to the method of the above embodiments; wherein when a power supply is provided to the anode and the cathode, an electric field is formed in the chlorine-containing solution, so that the chlorine ions in the chlorine-containing solution move to the chlorine-removing electrode as the anode and are electrochemically adsorbed on the chlorine-removing electrode.

[0010] Further, the anode and the cathode are both chlorine-removing electrodes prepared according to the method of the above embodiments.

[0011] Further, the device further comprises: a cation exchange membrane, the anode and the cathode being arranged on two sides of the cation exchange membrane, respectively, and two reaction chambers being formed on two sides of the cation exchange membrane, respectively; wherein during the electrochemical adsorption process, a purified liquid after treatment is formed in the reaction chamber on the anode side, and a concentrated waste liquid is formed in the reaction chamber on the cathode side; each reaction chamber is provided with a water outlet for discharging the purified liquid and the concentrated waste liquid, respectively.

[0012] Further, the device further comprises: a cation exchange membrane and an anion exchange membrane; the cation exchange membrane is arranged between the anode and the cathode, and the anion exchange membrane is arranged between the cation exchange membrane and the cathode, forming three reaction chambers; each reaction chamber is provided with a water outlet for discharging the purified liquid after treatment and the concentrated waste liquid, respectively.

[0013] In another aspect, the embodiments of the present application also provide an electrochemical chlorine-removing method which can remove chlorine ions in water by using the electrochemical chlorine-removing device in the above embodiments, the method comprising: continuously feeding a chlorine-containing solution to be treated into a reaction chamber; providing a power supply to an anode and a cathode, so that the chlorine ions in the chlorine-containing solution are electrochemically adsorbed on a chlorine-removing electrode as the anode, and a purified liquid is formed in the reaction chamber; continuously discharging the purified liquid after removal of the chlorine ions; when the chlorine-removing electrode as the anode is saturated with adsorption, exchanging the positive and negative poles of the power supply, so that the chlorine ions adsorbed on the chlorine-removing electrode are desorbed, and the chlorine-removing electrode is regenerated.

[0014] Further, the method further comprises: monitoring the chloride ion concentration of the purified liquid at the water outlet in real time; and determining whether the chloride removal electrode is saturated according to the change of the chloride ion concentration at the outlet.

[0015] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0016] 1. The variable valence metal hydroxide or variable valence metal oxide with a layered structure is used as the electrode material of the chloride removal electrode, which not only has low cost, but also has a large amount of adsorption of chloride ions, and can effectively remove chloride ions in water. After the chloride ions are inserted and saturated in the chloride removal electrode, the electrode can be regenerated, thereby realizing recycling.

[0017] 2. The layered hydroxide is used as the electrode material of the electrochemical insertion and removal chloride system, which fully utilizes the advantage of the anion intercalation property, and the connection between the layers relies on the electrostatic interaction force, thereby overcoming the shortcomings of large volume change and unstable structure of silver chloride and bismuth oxychloride as the electrode material before and after removing chloride ions.

[0018] 3. The present application utilizes the valence change of the layered variable valence metal when electrified to improve the adsorption capacity for chloride ions; and utilizes the controllability of the layered hydroxide metal layer to prepare a variety of insertion and removal type chloride removal electrodes by using a variety of different metals.

[0019] 4. The electrochemical chloride removal method of the present application reduces the common ion repulsion effect in the adsorption process by adding the cation membrane, so that the anode and the cathode can both use the prepared insertion and removal type layered metal hydroxide / oxide as the electrode material, which is simple to operate, low in cost, large in adsorption capacity, and convenient for continuous treatment.

[0020] The above technical solutions can be combined with each other in the present application to achieve more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purposes and other advantages of the present application can be achieved and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0022] Figure 1 It is an exploded structural schematic view of an electrochemical chloride removal device according to an embodiment of the present application.

[0023] Figure 2 It is an exploded structural schematic view of an electrochemical chloride removal device according to another embodiment of the present application. It is an exploded structural schematic view of an electrochemical chloride removal device according to another embodiment of the present application.

[0024] Figure 3 For Figure 2 The schematic diagram of the principle of removing chlorine by the electrochemical chlorine removal device.

[0025] Figure 4 The schematic diagram of the structure of the electrochemical chlorine removal device according to another embodiment of the present application.

[0026] Figure 5 The scanning electron microscope image of CoMgAl-LDH according to embodiment 1 of the present application.

[0027] Figure 6 The scanning electron microscope image of Ni5Ti-LDH according to embodiment 2 of the present application.

[0028] Figure 7 The column chart of the unit chlorine ion adsorption amount of CoMgAl-LDH and Ni5Ti-LDH according to the embodiments of the present application.

[0029] Explanation of reference signs:

[0030] 10-anode plate; 20-cathode plate; 30-silica gel plate; 40-hollow silica gel plate; 50-electrode fixing plate; 51-water inlet; 52-water outlet; 53-intermediate water outlet; 60-cation exchange membrane; 70-anion exchange membrane; 80-pipe. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the present application clearer, the exemplary embodiments of the present application will be described below with reference to the drawings. It should be understood that the specific embodiments described herein are merely used to explain the present application and should not be used to limit the present application. For the sake of clarity and conciseness, not all features of the actual embodiments are described in the specification.

[0032] It should also be noted that, in order to avoid obscuring the present application due to unnecessary details, only the device structures and / or processing steps closely related to the solutions according to the present application are shown in the drawings, and other details not closely related to the present application are omitted.

[0033] The embodiments of the present application provide a preparation method of a chlorine removal electrode. The method specifically comprises the following steps:

[0034] Step S1, preparing a chlorine removal nanomaterial, the chlorine removal nanomaterial being a variable valence metal hydroxide or a variable valence metal oxide with a layered structure;

[0035] Step S2, mixing the chlorine removal nanomaterial with a conductive agent and a bonding agent to obtain an electrode material;

[0036] Step S3, coating the electrode material on a conductive substrate to obtain a chlorine removal electrode.

[0037] The prepared chlorine-removing electrode of the embodiments of the present application is used for electrochemically removing chlorine ions in water. Specifically, the chlorine-removing electrode can be used as a capacitive deionization electrode. When a solution is treated by using the capacitive deionization technology, cations and anions in the solution move to the cathode and the anode of the capacitor respectively under the action of an electric field and are adsorbed on the electrode surface, thereby reducing the content of ions in the treated solution.

[0038] In the embodiments of the present application, when the chlorine-removing nanomaterial is used for electrochemically removing chlorine ions in water, the chlorine-removing nanomaterial can electrochemically adsorb the chlorine ions in water on the chlorine-removing electrode under the action of an electric field, thereby achieving the purpose of removing the chlorine ions in water. The use of layered variable-valence metal hydroxides or variable-valence metal oxides as the electrode material of the chlorine-removing electrode not only has low cost, but also has a large adsorption capacity for chlorine ions and can effectively remove the chlorine ions in water.

[0039] Specifically, the outer layer of the layered metal hydroxide is a metal layer formed by different metal ions, which exhibits positive electricity; the interlayer is filled with part of water molecules and anions, which exhibits negative electricity; therefore, the material as a whole exhibits electric neutrality. When the metal hydroxide is used as the electrode material of the anode, the positive and negative poles of the power supply are connected to the electrode and power is supplied to the electrode, under the action of an electric field, the metal layer of the metal hydroxide is converted from a low valence state to a high valence state, and its positive electricity is enhanced; the chlorine ions in water move to the anode under the action of an electric field, and after reaching the surface of the anode, they are inserted into the interlayer of the metal layer, and after saturation, a double electric layer is formed on the electrode surface by adsorption, thereby achieving the removal of the chlorine ions in water.

[0040] The interlayer anions of the metal oxide are mostly eliminated, and due to the structural memory effect, when it contacts a chlorine-containing solution, it can re-adsorb and combine chlorine ions to restore the layered structure; at the same time, under the action of an electric field, the metal layer of the metal oxide with restored layered structure is converted from a low valence state to a high valence state, further adsorbing chlorine ions and improving the adsorption rate of the metal oxide for chlorine ions. In addition, the metal oxide has a rich pore structure and a larger specific surface area, which is more conducive to the adsorption of chlorine ions.

[0041] In some embodiments of the present application, after the chlorine ions are inserted and adsorbed to saturation in the chlorine-removing electrode, the electrode can be regenerated, thereby realizing recycling. Specifically, the electrode can be disconnected from the power supply, or the positive and negative poles of the power supply can be reversely connected to the electrode, so that the chlorine-removing electrode originally serving as the anode serves as the cathode, thereby converting the metal layer of the metal hydroxide or the metal oxide from a high valence state to a low valence state, weakening the positive electricity, and desorbing the chlorine ions inserted between the layers and adsorbed on the surface of the material from the chlorine-removing electrode, thereby realizing the regeneration of the chlorine-removing electrode.

[0042] Currently, the capacitive deionization technology in the prior art is mainly used for desalination, wherein the anode material for adsorbing chlorine ions is mainly silver and bismuth, which removes chlorine ions in water by forming a new phase through reaction with chlorine ions. However, in the cyclic adsorption and regeneration process, the charging and discharging cause the new phase and the old phase to change constantly, resulting in a large volume change of the electrode material, which destroys the structure of the electrode material, reduces the cycle stability, and reduces the chlorine removal performance.

[0043] To avoid the above problems when silver and bismuth are used as the anode material, the embodiments of the present application use the layered structure of the variable valence metal hydroxide or variable valence metal oxide as the electrode material for electrochemical chlorine removal, fully utilizes the characteristics of the intercalation and deintercalation of anions in the layered structure, that is, the characteristics of the intercalation of anions, realizes the adsorption and removal of chlorine ions, and the layers are connected by electrostatic interaction force, the electrode has high stability, can be recycled and utilized, and overcomes the problem of unstable structure caused by the large volume change of chlorine ions before and after removal when silver chloride and bismuth oxychloride are used as the anode material. In addition, the embodiments of the present application also utilize the change of the valence of the variable valence metal in the layered metal hydroxide or metal oxide when electrified, improve the adsorption capacity of chlorine ions, and thus improve the removal rate of chlorine ions in water.

[0044] In some embodiments of the present application, the chlorine removal nanomaterial includes: first metal ions and second metal ions. The first metal ions are divalent metal ions, including at least one of Ni 2+ , Co 2+ , Ti 2+ , Cr 2+ , In 2+ , Zn 2+ and Mg 2+ ; and the second metal ions are trivalent or tetravalent metal ions, including at least one of Fe 3+ , Mn 3+ , Ti 3+ , Cr 3+ , Al 3+ , In 3+ , Co 3+ and Ti 4+ . The embodiments of the present application utilize the controllability of the metal layer plate of the layered metal hydroxide and metal oxide, and use the above-mentioned various metal ions to prepare various chlorine removal electrodes, thereby being suitable for water treatment in different situations and having good adaptability.

[0045] In some embodiments of the present application, the chlorine removal nanomaterial is prepared in step S1, and specifically includes the following steps:

[0046] Step S11, mixing and preparing metal salts corresponding to the first metal ions and the second metal ions to obtain a salt solution;

[0047] Step S12, the salt solution is mixed with the alkali solution, and a crystallization reaction or a hydrothermal reaction is performed to obtain the metal hydroxide.

[0048] Embodiments of the present application use a coprecipitation method or a hydrothermal method to prepare the layered metal hydroxide, and the preparation method is simple and low in cost.

[0049] Specifically, when the metal hydroxide is prepared by using the coprecipitation method, the soluble metal salts corresponding to the first metal ion and the second metal ion are dissolved in water to prepare a mixed salt solution; a certain concentration of alkali solution is prepared, the alkali solution is gradually added into the salt solution, so as to adjust the pH value of the salt solution to be within the range of 7-11, and a crystallization reaction is performed. Within the above pH value range, the nucleation and growth of the metal hydroxide crystals are facilitated.

[0050] Preferably, the concentration of the first metal ion in the mixed salt solution can be 0.1-1 mol / L, and the molar concentration ratio of the first metal ion to the second metal ion can be 1-3.

[0051] In some embodiments of the present application, in step S12, the alkali solution can be added into the mixed salt solution, and a crystallization reaction is performed. By using the dropwise addition method, the alkali solution can be slowly reacted with the salt solution, which helps to control the reaction rate, avoid local overheating or the generation of uneven precipitates due to too fast reaction, and more accurately control the pH value of the mixed solution, which helps to reduce the generation of impurities and improve the purity of the final product.

[0052] Preferably, when the crystallization reaction is performed, the crystallization can be performed at a temperature of 70-130°C for 12-36 hours. Within the temperature range, the metal ions can be fully reacted, and the metal hydroxide can be formed by crystallization.

[0053] When the metal hydroxide is prepared by using the hydrothermal method, the soluble metal salts corresponding to the first metal ion and the second metal ion are dissolved in water to prepare a mixed salt solution; a certain concentration of alkali solution is prepared, and the salt solution and the alkali solution are mixed and placed in a hydrothermal reaction kettle for hydrothermal reaction. Preferably, the reaction temperature of the hydrothermal reaction is 100-170°C, and the reaction time is 12-36 hours.

[0054] Preferably, the concentration of the first metal ion in the mixed salt solution can be 0.1-1 mol / L, and the molar concentration ratio of the first metal ion to the second metal ion can be 1-6.

[0055] In addition, after the crystallization reaction or the hydrothermal reaction is completed, the separated crystals can be washed to neutral with deionized water to remove the impurities remaining on the surface of the crystals, and then dried to obtain the metal hydroxide.

[0056] In some embodiments of the present application, the alkali solution used in step S12 is sodium hydroxide solution or urea solution. Specifically, when the metal hydroxide is prepared by the coprecipitation method, the alkali solution used can be sodium hydroxide solution or urea solution; when the metal hydroxide is prepared by the hydrothermal method, the alkali solution used can be urea solution. The embodiments of the present application use urea solution as the alkali solution to adjust the pH value of the metal salt solution, and can ensure that the pH value in the solution remains consistent, thereby facilitating the preparation of metal hydroxide crystals with high crystallinity and regular interlayer structure.

[0057] In some embodiments of the present application, in order to prepare layered metal oxide as the dechlorination nanomaterial, step S1 further comprises: step S13, calcining the metal hydroxide prepared in step S12 to obtain metal oxide. Specifically, the calcination temperature of the metal hydroxide can be 250-550°C. The metal oxide obtained after calcination has a more abundant pore structure and a larger specific surface area, which can expose more active sites, thereby facilitating the adsorption of chloride ions.

[0058] In some embodiments of the present application, after the dechlorination nanomaterial is prepared, the dechlorination nanomaterial can be mixed with a conductive agent and a binder to obtain an electrode material. The mass ratio of the dechlorination nanomaterial, the conductive agent and the binder is 6-8:1-3:1-3. Preferably, the mass ratio of the dechlorination nanomaterial, the conductive agent and the binder is 8:1:1, which can ensure the stability and good conductivity of the electrode in the case of more active substances.

[0059] In some embodiments, the dechlorination nanomaterial, the conductive agent and the binder can be mixed and ground to ensure uniform mixing of the three. The slurry obtained by grinding can be dried in a vacuum environment to obtain an electrode material for electrochemical dechlorination, for storage and standby. The drying temperature can be 60-80°C, and the drying time can be 12-24 hours.

[0060] Preferably, the conductive agent can be conductive carbon black, which can effectively improve the conductivity of the electrode material. Preferably, the binder comprises polyvinylidene fluoride. Specifically, the polyvinylidene fluoride can be mixed with a solvent N-methyl pyrrolidone to obtain a binder. The mass ratio of polyvinylidene fluoride to N-methyl pyrrolidone is 3%-6%.

[0061] In some embodiments of the present application, the conductive substrate used in step S3 can be carbon paper or titanium plate. After the electrode material slurry is obtained by mixing in step S2, the slurry can be coated on the carbon paper or titanium plate and vacuum dried to obtain the chlorine removal electrode. The coating thickness of the electrode material is 100-150 μm, so as to avoid the thickness being too thick and causing part of the active material not to be in full contact with the solution and not to play the adsorption role, which not only affects the unit adsorption amount of the electrode material, but also increases the cost of the electrode. In addition, the drying temperature can be 60-80 °C, and the drying time can be 12-24 hours.

[0062] The embodiments of the present application also provide an electrochemical chlorine removal device which removes chlorine ions in water by capacitive deionization technology. The electrochemical chlorine removal device comprises a reaction chamber, an anode and a cathode. The reaction chamber is used to accommodate the chlorine-containing solution to be treated, and the anode is the chlorine removal electrode in any of the above embodiments. When a power supply is provided to the anode and the cathode, an electric field is formed in the chlorine-containing solution, so that the chlorine ions in the chlorine-containing solution move to the chlorine removal electrode as the anode and are electrochemically adsorbed on the chlorine removal electrode. Specifically, the chlorine ions are intercalated between the metal layer plates of the chlorine removal electrode and are adsorbed on the surface of the chlorine removal electrode after intercalation saturation, so that the chlorine ions in the chlorine-containing solution are greatly reduced, achieving the purpose of removing chlorine ions.

[0063] In some embodiments of the present application, the cathode can use activated carbon as the electrode material. During the electrochemical chlorine removal process, the cations in the chlorine-containing solution move to the cathode.

[0064] In some other embodiments of the present application, both the anode and the cathode can use the chlorine removal electrode in any of the above embodiments. In this embodiment, when the chlorine removal electrode as the anode is saturated with electrochemically adsorbed chlorine ions, the positive and negative poles of the power supply can be exchanged, so that the original anode becomes a new cathode, and the original cathode becomes a new anode to adsorb chlorine ions, thereby realizing the regeneration of the original anode. The electrochemical chlorine removal device can realize the simultaneous electrochemical adsorption and electrode regeneration, and realize the continuous treatment of the chlorine-containing solution, greatly shortening the treatment time.

[0065] In addition, in some embodiments of the present application, a plurality of electrochemical chlorine removal devices can be used in series, so as to perform multi-stage adsorption treatment on the chlorine-containing solution, increase the adsorption amount of chlorine ions, and greatly reduce the concentration of chlorine ions in the solution.

[0066] In the embodiments of the present application, the chlorine removal electrode can be assembled into various types of electrochemical chlorine removal devices. The chlorine removal device can be provided with different numbers of ion exchange membranes, for example, 0, 1 or 2.

[0067] As Figure 1As shown, the film-free electrochemical chlorine removal device in the embodiment of the present application comprises an anode plate 10, a cathode plate 20, a silica gel plate 30, a hollow silica gel plate 40 and an electrode fixing plate 50 arranged in layers. The hollow silica gel plate 40 is arranged between the anode plate 10 and the cathode plate 20, and two electrode fixing plates 50 are symmetrically arranged on the two sides of the hollow silica gel plate 40 and are located at the outermost layer of the electrochemical chlorine removal device. Two silica gel plates 30 are symmetrically arranged on the outer sides of the anode plate 10 and the cathode plate 20. The hollow part of the hollow silica gel plate 40 constitutes a reaction chamber of the device. The anode plate 10 can be a chlorine removal electrode, the cathode plate 20 can be a titanium plate coated with activated carbon material, and the silica gel plate 30 can be used as a gasket to improve the sealing performance of the device and prevent liquid leakage. The various plates of the device are arranged in layers and are connected and fixed by insulating connectors (for example, insulating screws), thereby assembling the electrochemical chlorine removal device.

[0068] As shown in the figure, Figure 1 The electrode fixing plate 50 is provided with a water inlet 51 and a water outlet 52, and the silica gel plate 30 and the titanium plate are both provided with through holes. The chlorine-containing solution to be treated input from the water inlet 51 enters the reaction chamber through the through holes, and the purified liquid after treatment is transported to the water outlet 52 for discharge.

[0069] When the chlorine removal device of the embodiment is used for chlorine removal, the chlorine-containing solution can be continuously input from the water inlet 51 of the electrode fixing plate 50, and the power supply is connected between the anode plate 10 and the cathode plate 20 to apply an electric field to the chlorine-containing solution, so that the chloride ions in the chlorine-containing solution move to the anode plate 10 and are adsorbed on the chlorine removal nanomaterial, and the cations move to the cathode plate 20. Because the chloride ions in the chlorine-containing solution are adsorbed on the anode plate 10, the concentration of the chloride ions is reduced, and the purified liquid after the concentration of the chloride ions is reduced is continuously discharged from the water outlet 52 of the electrode fixing plate 50.

[0070] When the chloride ions are saturatedly adsorbed on the anode plate 10, the positive and negative electrodes of the power supply can be exchanged. At this time, the electric field in the chlorine-containing solution is reversed, and the chloride ions are desorbed from the saturatedly adsorbed anode plate 10. At this time, the water outlet 52 of the electrode fixing plate 50 discharges the concentrated waste liquid. The anode plate 10 is regenerated by reversing the electrodes, and after regeneration, the chlorine ions in the chlorine-containing solution can continue to be adsorbed.

[0071] In some embodiments of the present application, the chlorine removal electrode can also be used to assemble a single-film electrochemical chlorine removal device. The device further comprises a cation exchange membrane, and the anode and the cathode are arranged on the two sides of the cation exchange membrane, respectively. The two sides of the cation exchange membrane form a reaction chamber, respectively. In the electrochemical adsorption process, the reaction chamber on the anode side forms the purified liquid after treatment, and the reaction chamber on the cathode side forms the concentrated waste liquid. Each of the reaction chambers is provided with a water outlet for discharging the purified liquid and the concentrated waste liquid, respectively.

[0072] Specifically, asFigure 2 As shown, compared with the electrochemical dechlorination device without the membrane, the electrochemical dechlorination device in the embodiment further comprises a cation exchange membrane 60, the anode plate 10 and the cathode plate 20 are arranged on two sides of the cation exchange membrane 60 respectively, and the hollow silica gel plate 40 is arranged between the anode plate 10 and the cation exchange membrane 60 and between the cathode plate 20 and the cation exchange membrane 60 respectively, so that a reaction cavity is formed on each side of the cation exchange membrane. In the embodiment, the anode plate 10 and the cathode plate 20 can both be dechlorination electrodes. In the embodiment, the electrode fixing plate 50 on each side is provided with a water outlet 52 to discharge the solution in the two reaction cavities respectively.

[0073] When the dechlorination device in the embodiment is used for dechlorination, the chlorine-containing solution can be continuously input from the water inlet 51 of the electrode fixing plate 50, for example, Figure 3 As shown, after the power supply is connected between the anode plate 10 and the cathode plate 20 and an electric field is applied, the chloride ions in the chlorine-containing solution move to the anode plate 10 and are adsorbed on the dechlorination nanomaterial, the cations move to the cathode plate 20 and can pass through the cation exchange membrane 60 to the reaction cavity on the cathode side, so that the purified solution after removal of the chloride ions is formed in the reaction cavity on the anode side, and the concentrated waste solution is formed in the reaction cavity on the cathode side, and the purified solution and the concentrated waste solution are continuously discharged from the two water outlets 52 on the two sides respectively.

[0074] When the chloride ions on the anode plate 10 are saturatedly adsorbed, the positive and negative poles of the power supply can be exchanged. As shown, Figure 3 After the power supply is reversed, the anode plate 10 originally adsorbing the chloride ions becomes a new cathode, and the original cathode plate 20 becomes a new anode, the electric field in the chlorine-containing solution is reversed, the chloride ions are desorbed from the saturatedly adsorbed dechlorination electrode, so that the dechlorination electrode is regenerated, and at the same time, the other dechlorination electrode adsorbs the chloride ions until it is saturatedly adsorbed. By repeatedly exchanging the positive and negative poles of the power supply, the chloride ions can be continuously regenerated and adsorbed.

[0075] The embodiment of the present application reduces the homionic repulsion effect in the adsorption process by adding the cation exchange membrane, so that the prepared dechlorination nanomaterial can be used as the electrode on both the anode and the cathode. Moreover, the dechlorination device can realize the synchronous process of the electrochemical adsorption and regeneration, realizes the efficient enrichment and concentration of the chloride ions while purifying, greatly shortens the processing time, has the advantages of low cost, large adsorption capacity and convenient continuous treatment, and improves the removal amount and removal efficiency of the chloride ions.

[0076] In some embodiments of the present application, the chlorine removal electrode can also be assembled into a double-membrane type electrochemical chlorine removal device, which further comprises a cation exchange membrane and an anion exchange membrane, the cation exchange membrane is arranged between the anode and the cathode, and the anion exchange membrane is arranged between the cation exchange membrane and the cathode; and the device forms three reaction cavities, which are the reaction cavity on the anode side, the reaction cavity on the cathode side, and the reaction cavity formed between the two membranes, each reaction cavity is provided with a water outlet for discharging the treated purified liquid and the concentrated waste liquid. Among them, the anode can be the chlorine removal electrode of any of the above embodiments.

[0077] Specifically, as shown in Figure 4 Compared with the chlorine removal device without a membrane, the electrochemical chlorine removal device in this embodiment further comprises a cation exchange membrane 60 and an anion exchange membrane 70. The electrode fixing plate 50, the silica gel plate 30, the anode plate 10, the cation exchange membrane 60, the hollow silica gel plate 40, the anion exchange membrane 70, the cathode plate 20, the other silica gel plate 30 and the other electrode fixing plate 50 are sequentially stacked. Among them, the anode plate 10 is the chlorine removal electrode of any of the above embodiments, and the cathode plate 20 is a titanium plate coated with activated carbon material.

[0078] In this embodiment, the intermediate reaction cavity is formed between the cation exchange membrane 60 and the anion exchange membrane 70, which is called the concentrated water chamber; the two side reaction cavities are formed between the cation exchange membrane 60 and the silica gel plate 30, and between the anion exchange membrane 70 and the silica gel plate 30, which are called the dilute water chamber. The two electrode fixing plates 50 are provided with water outlets (not shown in the figure) to discharge the solution in the two side reaction cavities; at the same time, the electrode fixing plate 50 is also provided with an intermediate water outlet 53, which is communicated with the intermediate reaction cavity through a pipeline 80 to discharge the solution in the intermediate reaction cavity.

[0079] When the chlorine removal device of this embodiment is used for chlorine removal, the chlorine-containing solution can be continuously input from the water inlet of the electrode fixing plate 50. After the power supply is connected between the anode plate 10 and the cathode plate 20 and the electric field is applied, the chloride ions in the chlorine-containing solution move to the anode plate 10, part of the chloride ions (anode side chloride ions) are adsorbed on the anode plate 10, and the other part of the chloride ions (cathode side chloride ions) move to the anode plate 10 and pass through the anion exchange membrane 70 to reach the concentrated water chamber; the cations in the chlorine-containing solution move to the cathode plate 20, part of the cations (anode side cations) pass through the cation exchange membrane 60 to reach the concentrated water chamber. Thus, the concentrated waste liquid is formed in the intermediate concentrated water chamber, and the purified liquid after removal of chloride ions is formed in the two side dilute water chambers, the concentrated waste liquid is continuously discharged from the concentrated water chamber, and the purified liquid is continuously discharged from the dilute water chamber.

[0080] When the anode plate 10 is saturated with adsorption of chloride ions, the positive and negative poles of the power supply can be exchanged. After the power supply is reversed, the anode plate 10 originally adsorbing chloride ions becomes a new cathode, the electric field in the chloride-containing solution is reversed, and the chloride ions are desorbed from the saturated anode plate 10, so that the anode plate 10 is regenerated. At this time, the purified liquid is discharged from the concentrated water chamber, and the concentrated waste liquid is discharged from the dilute water chamber.

[0081] The electrochemical chlorine removal device in the embodiment of the present application has simple structure, low cost, and high electrode stability, can be operated at normal temperature and pressure, and has good adsorption effect on chloride ions, thereby improving the removal rate of chloride ions.

[0082] The embodiment of the present application also provides an electrochemical chlorine removal method, which can use any of the electrochemical chlorine removal devices described above to remove chloride ions in water. The electrochemical chlorine removal method in the embodiment includes the following steps:

[0083] continuously feeding the chloride-containing solution to be treated into the reaction chamber;

[0084] providing power supply to the anode and the cathode, so that the chloride ions in the chloride-containing solution are electrochemically adsorbed on the chlorine removal electrode as an anode, and purified liquid is formed in the reaction chamber;

[0085] continuously discharging the purified liquid after removal of chloride ions;

[0086] when the chlorine removal electrode as an anode is saturated with adsorption, the positive and negative poles of the power supply are exchanged, so that the adsorbed chloride ions are desorbed from the chlorine removal electrode, and the chlorine removal electrode is regenerated.

[0087] The electrochemical chlorine removal method of the embodiment of the present application has simple operation steps, can be implemented at normal temperature and pressure, has low production energy consumption and cost, and uses electrodes with high stability, so that the adsorption amount of chloride ions can be greatly improved, and the removal rate of chloride ions is high. In the process of removing chloride ions, no gas is generated, so that the operation of gas treatment is avoided, and the method is simple and efficient.

[0088] Specifically, when a membrane-free electrochemical chlorine removal device as shown in Figure 1 is used, the chloride-containing solution is continuously input from the water inlet 51 on the electrode fixing plate 50, and after the power supply is connected to apply an electric field, the chloride ions move to the anode plate 10 coated with the intercalation and deintercalation type chlorine removal material, and other cations move to the cathode plate 20 coated with the activated carbon material. The chloride ions are electrochemically adsorbed on the anode plate, thereby reducing the concentration of chloride ions in the solution, and forming purified liquid in the reaction chamber. The purified liquid is continuously discharged from the water outlet 52 on the electrode fixing plate 50.

[0089] When the anode plate 10 is saturated with adsorption, the water outlet 52 is connected to the waste liquid collection container, and then the positive and negative electrodes of the power supply are exchanged, so that the electric field is reversed, and the chloride ions are desorbed from the anode plate 10 to form concentrated waste liquid which is collected in the waste liquid collection container, so that the anode plate 10 is regenerated. When the anode plate 10 is regenerated, the positive and negative electrodes of the power supply are exchanged again, so that the anode plate 10 can continue to adsorb chloride ions.

[0090] When the single-membrane type electrochemical dechlorination device as shown in Figure 2 is used, the chlorine-containing solution is continuously input from the water inlet 51 on the electrode fixing plate 50, and the water outlet on one side of the cathode plate 10 is connected to the waste liquid collection container. After the power supply is connected and an electric field is applied, the chloride ions in the chlorine-containing solution move to the anode plate 10 and are adsorbed on the dechlorination nanomaterial, and the cations move to the cathode plate 20 and can pass through the cation exchange membrane 60 to reach the reaction cavity on the cathode side, so that the purified liquid after removal of chloride ions is formed in the reaction cavity on one side of the anode plate 10, and the purified liquid is continuously discharged from the water outlet 52 on one side of the anode plate 20. The concentrated waste liquid is formed in the reaction cavity on one side of the cathode plate 20 and is continuously discharged from the other water outlet 52 to the waste liquid collection container.

[0091] When the anode plate 10 is saturated with adsorption, the water outlet 52 is connected to the waste liquid collection container, and then the positive and negative electrodes of the power supply are exchanged, so that the electric field is reversed, and the chloride ions are desorbed from the anode plate 10 to form concentrated waste liquid which is collected in the waste liquid collection container, so that the anode plate 10 is regenerated. When the anode plate 10 is regenerated, the positive and negative electrodes of the power supply are exchanged again, so that the anode plate 10 can continue to adsorb chloride ions.

[0092] By repeatedly exchanging the positive and negative electrodes of the power supply, the dechlorination electrode is continuously regenerated and adsorbs chloride ions. When the positive and negative electrodes of the power supply are exchanged, the two water outlets 52 also need to exchange the interfaces.

[0093] When the single-membrane type electrochemical dechlorination device as shown in Figure 4 is used, the chlorine-containing solution is continuously input from the water inlet 51 on the electrode fixing plate 50, and the water outlet on one side of the cathode plate 10 is connected to the waste liquid collection container. After the power supply is connected and an electric field is applied, the chloride ions in the chlorine-containing solution move to the anode plate 10 and are adsorbed on the dechlorination nanomaterial, and the cations move to the cathode plate 20 and can pass through the cation exchange membrane 60 to reach the reaction cavity on the cathode side, so that the purified liquid after removal of chloride ions is formed in the reaction cavity on one side of the anode plate 10, and the purified liquid is continuously discharged from the water outlet 52 on one side of the anode plate 20. The concentrated waste liquid is formed in the reaction cavity on one side of the cathode plate 20 and is continuously discharged from the other water outlet 52 to the waste liquid collection container.

[0094] When the anode plate 10 is saturated with adsorption of chloride ions, the water outlets of the fresh water chambers on both sides are connected to a waste liquid collecting container, the positive and negative electrodes of the power supply are exchanged, the anode plate 10 originally adsorbing chloride ions becomes a new cathode, and the chloride ions are desorbed from the saturated anode plate 10 to form concentrated waste liquid in the fresh water chamber, which is continuously discharged from the water outlet to the solution collecting container, while the purified liquid is continuously discharged from the middle water outlet 53. When the anode plate 10 is regenerated, the positive and negative electrodes of the power supply are exchanged again, so that the anode plate 10 can continue to adsorb chloride ions.

[0095] The dechlorination method of the embodiment of the present application can use three different types of dechlorination devices for different situations of chloride-containing solutions, and has the advantages of simple operation, low cost, large adsorption capacity, and convenient continuous treatment. For example, when the environment of the chloride-containing solution to be treated is complex and there are multiple anions and cations, an electrochemical dechlorination device with an ion exchange membrane can be used to help reduce the "co-ion effect", improve the charge efficiency, reduce energy consumption, and improve the removal rate of chloride ions; when the anions and cations in the chloride-containing solution are single, a membrane-free electrochemical dechlorination device can be used to reduce costs.

[0096] In some embodiments of the present application, the electrochemical dechlorination method further comprises the steps of: monitoring the chloride ion concentration of the purified liquid at the water outlet in real time; and determining whether the dechlorination electrode is saturated according to the change of the chloride ion concentration at the outlet. The method of the embodiment can determine whether the dechlorination electrode as the anode is saturated in time, so as to exchange the positive and negative electrodes of the power supply in time to regenerate it, while ensuring that the chloride ion content in the discharged purified liquid is low to ensure that the discharged purified liquid is qualified.

[0097] Specifically, when the chloride ion concentration of the purified liquid at the water outlet decreases by a small value within a certain time, it is determined that the dechlorination electrode is basically saturated. For example, when the decrease rate of the chloride ion concentration of the purified liquid at the outlet is lower than a predetermined value, it is determined that the dechlorination electrode is saturated. The predetermined value can be set according to actual conditions.

[0098] In order to illustrate the feasibility of the above-mentioned embodiments of the present application, the preparation method of the dechlorination electrode and the electrochemical dechlorination method provided by the present application are further described below in combination with the drawings and specific embodiments.

[0099] Embodiment 1

[0100] Step S1, preparation of dechlorination nanomaterial:

[0101] 0.1 mol of Co(NO3)2·6H2O, 1.5 mol of Mg(NO3)2·6H2O, 0.8 mol of Al(NO3)3·9H2O and 3.2 mol of urea were completely dissolved in 250 mL of deionized water, placed in a 500 mL high-pressure reaction kettle, and put into an oven for hydrothermal reaction at 140°C for 24 hours. After the reaction was completed, it was cooled to room temperature, and the product was separated by centrifugation. The obtained product was repeatedly washed with deionized water for 5 times, and then moved into an oven at 80°C for drying overnight to obtain the intercalation-deintercalation type chlorine removal nanomaterial CoMgAl-LDH. As shown in FIG. 2, the CoMgAl-LDH exhibits a clear layered structure. Figure 5

[0102] Step S2, preparation of electrode material:

[0103] First, the adhesive was prepared. Polyvinylidene fluoride and N-methyl pyrrolidone were mixed at a mass ratio of 4% and stirred until the polyvinylidene fluoride white powder was completely dissolved.

[0104] Then, CoMgAl-LDH, conductive carbon black and the above adhesive were mixed and ground at a mass ratio of 8:1:1, and the electrode material slurry was obtained after uniform grinding.

[0105] Step S3, the electrode slurry obtained in step S2 was uniformly coated on a titanium plate by a doctor blade, and the coating thickness was 100 μm. After coating, vacuum drying was carried out at a temperature of 60°C for 24 hours to obtain a chlorine removal electrode.

[0106] Example 2

[0107] Step S1, preparation of chlorine removal nanomaterial:

[0108] 0.5 ml, 0.002 mol of TiCl4 solution and 0.01 mol of Ni(NO3)2·6H2O were mixed and prepared into a 25 mL metal salt solution. The molar ratio of Ni 2+ to Ti 4+ was 5:1. The TiCl4 solution was prepared by mixing TiCl4 and HCl in equal volumes. The use of hydrochloric acid provides an acidic environment, which can effectively prevent the hydrolysis of Ti 4+ in the solution.

[0109] 75 ml of an aqueous solution containing 0.1 mol of urea and 0.02 mol of Na2CO3 was added dropwise to the metal salt solution, and stirred vigorously until the pH value of the solution reached 10. Then, it was stirred at reflux temperature for 24 h. After the reaction was completed, the precipitate was separated, and the precipitate was repeatedly washed with deionized water for 5 times, and then moved into an oven at 80°C for drying overnight to obtain Ni5Ti-LDH. Figure 6 The scanning electron microscope image of Ni5Ti-LDH is shown. In addition, Ni​2+ with Ti 4+ The preparation method is similar to the above method, only the content of titanium element is changed.

[0110] Next, the Ni5Ti-LDH, conductive carbon black and the above binder are mixed and ground in a mass ratio of 8:1:1, and after uniform grinding, an electrode material slurry is obtained.

[0111] Step S3, the electrode slurry obtained in step S2 is uniformly coated on a titanium plate by a doctor blade, the coating thickness is 100 pm, and after coating, vacuum drying is performed at a temperature of 60°C for 24 hours to obtain a chlorine removal electrode.

[0112] Example 3

[0113] The chlorine removal electrodes of Example 1 and Example 2 are respectively used as anodes to assemble a membrane-free electrochemical chlorine removal device as shown in Figure 1 . Among them, the active area of the electrode material of the anode is 4x4 cm, and the electrode spacing between the anode and the cathode is about 1 mm.

[0114] The electrochemical chlorine removal device is used to remove chlorine from a chlorine-containing solution, and the applied voltage is 1.2 V. Among them, the chlorine-containing solution is desulfurized gypsum wastewater with different concentrations of chloride ions, and the chloride ion concentrations are 300 mg / L -1 , 600 mg / L -1 , 1500 mg / L -1 , and 2000 mg / L -1 , and the volume is 50 mL.

[0115] The adsorption effect of chloride ions in the chlorine-containing solution when CoMgAl-LDH in Example 1 and Ni5Ti-LDH in Example 2 are used as electrode materials of chlorine removal electrodes is shown in Table 1 and Figure 7 . Table 1 shows the removal effect of CoMgAl-LDH and Ni5Ti-LDH on chloride ions under different initial concentrations of chloride ions

[0116] Chloride initial concentration (mg L -1 )]]> 300 600 1500 2000 [CD AT] The Ni5Ti-LDH unit adsorption capacity (mg g -1 ) 69.53 107.62 230.45 301.45 [Table 5: Chloride ion concentration (mg L -1 ) after treatment with Ni5Ti-LDH 78 112 154 200 [cl- removal rate of ni5ti-ldh] 74.00％ 81.33％ 89.73％ 90.00％ CoMgAl-LDH unit adsorption capacity (mg g -1 )]]> 56.43 83.54 185.14 265.41 CoMgAl-LDH treated after chloride concentration (mg L -1 )]]> 96 155 183 274 CoMgAl-LDH chloride ion removal rate 68.00％ 74.17％ 87.80％ 86.30％

[0117] Referring to Table 1 and Figure 7 , with the increase of the initial concentration of chloride ions in the chlorine-containing solution, the unit adsorption amount of Ni5Ti-LDH and CoMgAl-LDH on chloride ions gradually increases, and the removal rate of chloride ions also increases and gradually reaches saturation. Among them, when the concentration of chloride ions is 2000 mg / L -1 , the unit adsorption amount of CoMgAl-LDH on chloride ions is 265.14 mg / g -1 , and the unit adsorption amount of Ni5Ti-LDH on chloride ions is as high as 301.45 mg / g -1. When the initial concentration of chloride ions is 2000 mg / L -1 , the removal rate of Ni5Ti-LDH for chloride ions can reach 90%; when the initial concentration of chloride ions is 1500 mg / L -1 , the removal rate of CoMgAl-LDH for chloride ions reaches a maximum of 87.40%.

[0118] Example 4

[0119] CoMgAl-LDH in Example 1 and Ni5Ti-LDH in Example 2 were mixed with conductive agents and adhesives in different mass ratios to prepare chloride removal electrodes, and the remaining conditions were the same as in Example 1.

[0120] The chloride removal electrodes were assembled into a membrane-free electrochemical chloride removal device as shown in Figure 1 , and the device was used to remove chloride from a solution containing chloride, which was 50 mL of desulfurized gypsum wastewater with a chloride ion concentration of 1500 mg / L -1 , and the remaining conditions were the same as in Example 3.

[0121] The adsorption effect of the electrochemical chloride removal device on chloride ions in the solution containing chloride is shown in Table 2. With the increase of the mass ratio of CoMgAl-LDH or Ni5Ti-LDH in the electrode material, the unit adsorption amount of CoMgAl-LDH and Ni5Ti-LDH for chloride ions also gradually increases, and the removal rate of chloride ions also gradually increases. When the mass ratio is 8:1:1, the removal rate of chloride ions is higher, and the stability of the electrode is better, which can ensure that the electrode material will not fall off from the conductive matrix.

[0122] Table 2 Removal effect statistics of CoMgAl-LDH and Ni5Ti-LDH with different mass ratios on chloride ions under an initial concentration of 1500 mg / L -1 of chloride ions

[0123] Mass ratio 8:1:1 7:2:1 6:3:1 6:1:3 [CD AT] The Ni5Ti-LDH unit adsorption capacity (mg g -1 ) 230.45 200.27 150.69 90.22 [Ni5Ti-LDH treatment after chloride ion concentration (mg L -1 )]]> 154 186 258 316 [cl- removal rate of ni5ti-ldh] 89.73％ 87.60％ 82.80％ 78.93％ CoMgAl-LDH unit adsorption capacity (mg g -1 ) 185.14 167.85 108.64 59.87 CoMgAl-LDH treated after chloride concentration (mg L -1 )]]> 183 199 245 265 CoMgAl-LDH chloride ion removal rate 87.80％ 86.73％ 83.67％ 82.33％

[0124] Example 5

[0125] CoMgAl-LDH in Example 1 and Ni5Ti-LDH in Example 2 were mixed with conductive agents and adhesives in a mass ratio of 8:1:1 to prepare electrode materials. The electrode materials were coated on a titanium plate in different thicknesses to prepare chloride removal electrodes, and the remaining conditions were the same as in Example 1.

[0126] The chloride removal electrodes were assembled into a membrane-free electrochemical chloride removal device as shown in Figure 1 , and the device was used to remove chloride from a solution containing chloride, which was 50 mL of desulfurized gypsum wastewater with a chloride ion concentration of 1500 mg / L -1 , and the remaining conditions were the same as in Example 3.

[0127] The removal effect of the electrochemical chlorine removal device on the chlorine ions in the chlorine-containing solution is shown in Table 3. With the increase of the coating thickness of the electrode material, although the chlorine ion removal rate increases, the chlorine ion removal rates corresponding to different coating thicknesses are not much different, and the unit adsorption amount of the chlorine ions by CoMgAl-LDH and Ni5Ti-LDH gradually decreases, especially when the coating thickness is greater than 150 μm, the unit adsorption amount of the chlorine ions by CoMgAl-LDH and Ni5Ti-LDH greatly decreases. When the coating thickness of the electrode material is 100-150 μm, the unit adsorption amount of the chlorine ions by the electrode material is high while ensuring the chlorine ion removal rate, and the electrode material can be fully utilized.

[0128] Table 3 Removal effect of CoMgAl-LDH and Ni5Ti-LDH with different coating thicknesses on chlorine ions under the condition that the initial concentration of chlorine ions is 1500 mg / L -1 Table 4 Removal effect of different chlorine removal devices using Ni5Ti-LDH electrode material on chlorine ions under the condition that the initial concentration of chlorine ions is 1500 mg / L

[0129] Coating thickness pm 100 150 200 300 [CD AT] The Ni5Ti-LDH unit adsorption capacity (mg g -1 )]]> 230.45 203.85 129.65 88.69 [Ni5Ti-LDH treatment after chloride ion concentration (mg L -1 )]]> 154 150 148 130 [cl- removal rate of ni5ti-ldh] 89.73％ 90.00％ 90.13％ 91.33％ CoMgAl-LDH unit adsorption capacity (mg g -1 )]]> 185.14 153.64 93.44 65.13 CoMgAl-LDH treated after chloride concentration (mg L -1 )]]> 183 180 178 168 CoMgAl-LDH chloride ion removal rate 87.80％ 88.00％ 88.13％ 88.80％

[0130] Example 6

[0131] The chlorine removal electrodes in Example 2 are assembled into different types of electrochemical chlorine removal devices, respectively, and different types of electrochemical chlorine removal devices are used to remove chlorine from a chlorine-containing solution, wherein the chlorine-containing solution is desulfurized gypsum wastewater with a chlorine ion concentration of 1500 mg / L -1 , and the rest is the same as in Example 3.

[0132] The removal effect of different types of electrochemical chlorine removal devices on the chlorine ions in the chlorine-containing solution is shown in Table 4. The increase of the ion exchange membrane in the electrochemical chlorine removal device increases the unit adsorption amount of the chlorine ions by the Ni5Ti-LDH electrode material and the chlorine ion removal rate. When the double-membrane type electrochemical chlorine removal device is used, the chlorine ion removal rate is as high as 96.07%.

[0133] Table 4 Removal effect of different chlorine removal devices using Ni5Ti-LDH electrode material on chlorine ions under the condition that the initial concentration of chlorine ions is 1500 mg / L -1

[0134]

[0135] Example 7

[0136] CoMgAl-LDH in Example 1 is calcined at 450°C for 6 hours to obtain layered metal oxide CoMgAl-LDO.

[0137] A chlorine removal electrode is prepared using CoMgAl-LDO, and the electrode preparation method is the same as in Example 1. The chlorine removal electrode is assembled into an electrochemical chlorine removal device as shown in Figure 1 ​The membrane-free electrochemical dechlorination device is used for dechlorination of a chlorine-containing solution, wherein the chlorine-containing solution is desulfurized gypsum wastewater with a chlorine ion concentration of 1500 mg / L -1 , and the rest is the same as in Example 3.

[0138] The chlorine ion concentration in the chlorine-containing solution before and after dechlorination by the electrochemical dechlorination device is measured, and the removal rate of the chlorine ion in the chlorine-containing solution by the electrochemical dechlorination device is obtained, as shown in Table 5. Compared with CoMgAl-LDH, the unit adsorption amount of the calcined CoMgAl-LDO for chlorine ions is larger, and the corresponding chlorine ion removal rate is also larger, which can reach more than 90%.

[0139] The embodiment of the present application has a larger specific surface area and a more abundant pore structure by calcination, which can expose more active sites, and is beneficial to improve the adsorption amount of chlorine ions.

[0140] Table 5 Removal effect comparison of chlorine ions with an initial concentration of 1500 mg / L -1 of CoMgAl-LDH and calcined CoMgAl-LDO

[0141]

[0142] Example 8

[0143] The Ni5Ti-LDH dechlorination electrode in Example 2 is used to assemble a membrane-free electrochemical dechlorination device as shown in Figure 1 .

[0144] In the case of no electricity, 50 mL of chlorine-containing solution is transported into the electrochemical dechlorination device for adsorption dechlorination, and the chlorine ion concentration in the discharged treated solution is measured. The electrochemical dechlorination device is powered on, the voltage is 1.2 V, 50 mL of chlorine-containing solution is transported into the electrochemical dechlorination device for electrochemical adsorption dechlorination, and the chlorine ion concentration in the discharged treated solution is measured. The chlorine-containing solution is desulfurized gypsum wastewater with a chlorine ion concentration of 1500 mg / L -1 , and the rest is the same as in Example 3.

[0145] The adsorption amount of chlorine ions and the chlorine ion removal rate of the electrochemical dechlorination device before and after power-on are compared, as shown in Table 6. Compared with the case of no power-on, the unit adsorption amount of the Ni5Ti-LDH material for chlorine ions is obviously increased after power-on, and the chlorine ion removal rate is also greatly improved.

[0146] The embodiment of the present application utilizes the change in valence of the interlayer variable valence metal in the dechlorination nanomaterial when powered on to improve the adsorption capacity for chlorine ions.

[0147] Table 6 Removal effect comparison of chlorine ions with an initial concentration of 1500 mg / L-1 Comparison of chlorine ion removal effect of dechlorination device before and after power on under the following table

[0148]

[0149] The above merely provides the preferred but non-limiting embodiment of the present application, and the protection scope of the present application should not be limited thereto, and any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for producing a chlorine-removing electrode, characterized by, The chlorine-removing electrode is used for electrochemical adsorption removal of chloride ions in water, and the preparation method comprises the following steps: Preparation of a chlorine-removing nanomaterial, which is a variable valence metal hydroxide or variable valence metal oxide in a layered structure; the chlorine-removing nanomaterial comprises: first metal ions and second metal ions; wherein the first metal ions are at least one of Co 2+ and Mg 2+ ; the second metal ions are Al 3+ ; The chlorine-removing nanomaterial is mixed with a conductive agent and a binder to obtain an electrode material; The electrode material is coated on a conductive substrate to obtain the chlorine-removing electrode; The chlorine-removing nanomaterial can electrochemically adsorb chloride ions in water on the chlorine-removing electrode under the action of an electric field, so as to remove the chloride ions in water. The preparation of the chlorine-removing nanomaterial comprises the following steps: The metal salts corresponding to the first metal ions and the second metal ions are mixed to obtain a salt solution; The salt solution is mixed with an alkali solution, and a crystallization reaction or a hydrothermal reaction is performed to obtain the variable-valence metal hydroxide.

2. The method of claim 1, wherein the dechlorination electrode is prepared by the steps of: The concentration of the first metal ions in the mixed salt solution is 0.1-1 mol / L, and the molar concentration ratio of the first metal ions to the second metal ions is 1-3.

3. The method of claim 2, wherein the dechlorination electrode is prepared by the steps of: The reaction temperature of the hydrothermal reaction is 100-170 ℃, and the reaction time is 12-36 hours; when the crystallization reaction is performed, the crystallization is performed at a temperature of 70-130 ℃ for 12-36 hours.

4. The method of claim 1 or 3, wherein the method further comprises the step of: The preparation of the chlorine-removing nanomaterial further comprises the following step: The variable-valence metal hydroxide is calcined to obtain the variable-valence metal oxide.

5. An electrochemical chlorine removal device for removing chloride ions from water, characterized in that, Comprises: a reaction chamber for containing a chlorine-containing solution to be treated; an anode and a cathode, the anode being a chlorine-removing electrode prepared according to the preparation method of the chlorine-removing electrode of any one of claims 1-4; When a power supply is provided to the anode and the cathode, an electric field is formed in the chlorine-containing solution, so that the chloride ions in the chlorine-containing solution move to the chlorine-removing electrode as the anode and are electrochemically adsorbed on the chlorine-removing electrode.

6. An electrochemical dechlorination device according to claim 5, wherein The anode and the cathode are both chlorine-removing electrodes prepared according to the preparation method of the chlorine-removing electrode of any one of claims 1-4.

7. An electrochemical dechlorination device according to claim 6, wherein Further comprises: a cation exchange membrane, the anode and the cathode being arranged on two sides of the cation exchange membrane, respectively, and each side of the cation exchange membrane forming a reaction chamber; wherein, during the electrochemical adsorption process, a purified liquid after treatment is formed in the reaction chamber on the anode side, and a concentrated waste liquid is formed in the reaction chamber on the cathode side; Each of the reaction chambers is provided with a water outlet for discharging the purified liquid and the concentrated waste liquid, respectively.

8. An electrochemical dechlorination device according to claim 5, wherein Further comprises: a cation exchange membrane and an anion exchange membrane; the cation exchange membrane is arranged between the anode and the cathode, and the anion exchange membrane is arranged between the cation exchange membrane and the cathode, forming three reaction chambers; Each of the reaction chambers is provided with a water outlet for discharging the purified liquid after treatment and the concentrated waste liquid, respectively.

9. An electrochemical dechlorination method, characterized by, The electrochemical chlorine-removing device according to any one of claims 5-8 is used to remove chloride ions in water, which comprises the following steps: continuously feeding the chlorine-containing solution to be treated into the reaction chamber; providing a power supply to the anode and the cathode, so that the chloride ions in the chlorine-containing solution are electrochemically adsorbed on the chlorine-removing electrode as the anode, and a purified liquid is formed in the reaction chamber; continuously discharging the purified liquid after removal of the chloride ions; when the chlorine-removing electrode as the anode is saturated with adsorption, the positive and negative poles of the power supply are exchanged, so that the chloride ions adsorbed on the chlorine-removing electrode are desorbed, and the chlorine-removing electrode is regenerated.

10. The method of claim 9, wherein the method further comprises: Further comprises: Real-time monitoring of the chloride ion concentration of the purified liquid at the water outlet; According to the change of the chloride ion concentration at the water outlet, it is determined whether the dechlorination electrode is saturated.

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