A method for removing chloride ions, a method for high-value utilization, and a preparation method

Abstract

The present invention provides a method for removing chloride ions, a method for high-value utilization, and a preparation method; the method for removing chloride ions comprises the following steps: S1, providing a capacitive deionization device, wherein the anode of the capacitive deionization device is a copper electrode, the copper electrode contains a copper material, and the mass proportion of the copper element in the copper material is 20-70%; S2, placing chlorine-containing wastewater in the capacitive deionization device for electrochemical reaction to achieve the removal of chloride ions in the chlorine-containing wastewater; wherein the applied voltage of the electrochemical reaction is 1.0-1.4V. The present invention adopts a copper electrode and processes chloride ions electrochemically, which can be applied to the field of wastewater treatment in a high-value manner and can effectively reduce treatment costs.

Description

Technical Field

[0001] The present invention relates to the treatment of chlorine-containing wastewater, and in particular to a method for removing chloride ions, a method for high-value utilization thereof, and a preparation method. Background Art

[0002] With the development of industry, the amount of industrial wastewater containing chloride ions is increasing. These chloride ions can cause various corrosion conditions in piping systems, leading to corrosion and cracking of equipment and malfunction. Removing chloride ions from industrial wastewater is a major issue in environmental protection and reducing economic losses.

[0003] Currently, the main treatment methods for chlorine-containing wastewater include precipitation, ion exchange, adsorption, membrane separation, and capacitive deionization technology. However, these technologies can only reduce the concentration of chloride ions and cannot achieve high value. For example, the Chinese invention patent application with publication number CN112194282A describes a method for chemically removing chloride ions. Specifically, calcium oxide and sodium aluminate are added to chlorine-containing wastewater, stirred at 25-40°C for 30-120 minutes, and solid-liquid separation is performed to obtain wastewater with chloride ions removed; wherein the molar ratio of calcium oxide to sodium aluminate is 2:1-4:1.

[0004] The aforementioned patent application uses calcium oxide and sodium metaaluminate as reagents, which can remove chloride ions from chlorine-containing wastewater to a certain extent; however, it does not achieve high-value utilization of the chloride ions in the chlorine-containing wastewater. In addition, there are also reports on the preparation of chloride ions into sodium chloride products to achieve resource recovery; however, sodium chloride is cheap and far less than the recycling cost. Therefore, the high-value removal of chloride ions from chlorine-containing wastewater is the goal of existing technology development.

[0005] In view of this, it is necessary to provide a method for removing chloride ions, a method for high-value utilization and a preparation method to solve or at least alleviate the technical defects of low high-value utilization of chlorine-containing wastewater and / or low chloride ion removal efficiency. Summary of the Invention

[0006] The main purpose of the present invention is to provide a method for removing chloride ions, a method for high-value utilization and a preparation method, aiming to solve the technical problems of low high-value utilization of chlorine-containing wastewater and / or low chloride ion removal efficiency.

[0007] To achieve the above object, the present invention provides a method for removing chloride ions in chlorine-containing wastewater, comprising the steps of:

[0008] S1, providing a capacitive deionization device, wherein the anode of the capacitive deionization device is a copper electrode, the copper electrode contains a copper material, and the mass proportion of the copper element in the copper material is 20-70%;

[0009] S2, placing the chlorine-containing wastewater in the capacitive deionization device for electrochemical reaction to achieve the removal of chloride ions in the chlorine-containing wastewater; wherein the external voltage of the electrochemical reaction is 1.0-1.4V.

[0010] Furthermore, the concentration of chloride ions in the chlorine-containing wastewater is not less than 1000 mg / L.

[0011] Furthermore, the pH of the chlorine-containing wastewater is 5-8.

[0012] Furthermore, the copper material includes a coating material, and the coating material includes copper powder and a binder.

[0013] Furthermore, the binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, and sodium carboxymethyl cellulose.

[0014] Furthermore, the copper material includes at least one of copper foil, copper plate, and copper rod.

[0015] Furthermore, the electrochemical reaction lasts for 20 to 90 minutes.

[0016] Furthermore, the cathode of the capacitive deionization device is an activated carbon electrode.

[0017] The present invention also provides a method for high-value utilization of chlorine-containing wastewater, comprising: placing the chlorine-containing wastewater in a capacitive deionization device for electrochemical reaction, wherein the anode of the capacitive deionization device is a copper electrode;

[0018] The copper electrode contains copper material, and the mass proportion of copper element in the copper material is 25-35%; the external voltage of the electrochemical reaction is 1.0-1.4V.

[0019] The present invention also provides a method for preparing basic copper chloride, comprising: placing a chlorine-containing solution in a capacitive deionization device for electrochemical reaction, wherein the anode of the capacitive deionization device is a copper electrode;

[0020] The copper electrode contains copper material, and the mass proportion of copper element in the copper material is 25-35%; the external voltage of the electrochemical reaction is 1.0-1.4V.

[0021] Compared with the prior art, the present invention has at least the following advantages:

[0022] 1. The present invention proposes a treatment technology for high-concentration chloride ion wastewater, which is the first to achieve chloride ion removal by obtaining a basic copper chloride product; that is, it is the first time that an electrochemical method is used to treat chloride ions and the high-value application is applied in the field of wastewater treatment, effectively reducing treatment costs.

[0023] 2. The present invention uses Cu electrode, Cu and Cl- The generated basic copper chloride is a high-value product, which not only achieves the removal of chloride ions, but also can obtain certain economic benefits while treating wastewater.

[0024] 3. The electrochemical method of the present invention has low control potential and low energy consumption and is suitable for practical applications.

[0025] 4. The pH range of wastewater that can be treated by the present invention is wide, and it is applicable to a variety of chloride ion-containing wastewaters; the chloride ion concentration that can be treated is high, which solves the problem of high chlorine in industry that is difficult to open the circuit.

[0026] 5. The treatment method of the present invention requires simple equipment, is simple and easy to operate, and can be operated continuously, thus being suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0028] Figure 1 This is a comparison chart of the dechlorination effects of different copper electrodes in Example 2 of the present invention;

[0029] Figure 2 1 is a comparison of XRD patterns of different copper electrodes after 1 h of electrochemical reaction in Example 2 of the present invention;

[0030] Figure 3 This is a comparison diagram of the dechlorination effect at different voltages (working electrode potentials) in Example 3 of the present invention;

[0031] Figure 4 The XRD comparison diagram of the copper electrode (CuNPs-15) at different voltages after 1 hour of reaction in Example 3 of the present invention;

[0032] Figure 5 For different initial Cl in Example 4 of the present invention - Comparison of dechlorination effects under different concentrations (sodium chloride concentrations).

[0033] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making any creative efforts are within the scope of protection of the present invention.

[0035] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0036] Since the chloride ions present in chlorine-containing wastewater can cause corrosion and cracking of equipment, it is necessary to remove the chloride ions in the chlorine-containing wastewater efficiently and quickly. In order to achieve the removal of chloride ions in chlorine-containing wastewater, the present invention provides a method for removing chloride ions in chlorine-containing wastewater, comprising the steps of:

[0037] S1. Provide a capacitive deionization device, wherein the anode of the capacitive deionization device is a copper electrode. The copper electrode contains a copper material, and the mass proportion of the copper element in the copper material is 20-70%.

[0038] S2, placing the chlorine-containing wastewater in the capacitive deionization device for electrochemical reaction to achieve the removal of chloride ions in the chlorine-containing wastewater; wherein the external voltage of the electrochemical reaction is 1.0-1.4V.

[0039] In order to realize the high value of chlorine-containing wastewater, it is necessary to increase the value of chloride ions while removing chloride ions. Therefore, the present invention also provides a method for high value utilization of chlorine-containing wastewater, comprising: placing the chlorine-containing wastewater in a capacitive deionization device for electrochemical reaction.

[0040] The anode of the capacitive deionization device is a copper electrode, which contains copper material, and the mass proportion of copper element in the copper material is 25-35%; the external voltage of the electrochemical reaction is 1.0-1.4V.

[0041] In order to obtain basic copper chloride based on a thallium-containing solution, the present invention provides a method for preparing basic copper chloride, comprising: placing a chlorine-containing solution in a capacitive deionization device for an electrochemical reaction; the chlorine-containing solution can be chlorine-containing wastewater or other solutions containing chloride ions, and the chlorine-containing solution contains chloride ions, specifically sodium chloride.

[0042] The anode of the capacitive deionization device is a copper electrode, which contains copper material, and the mass proportion of copper element in the copper material is 25-35%; the external voltage of the electrochemical reaction is 1.0-1.4V.

[0043] In the present invention, the concentration of chloride ions in the chlorine-containing wastewater or the chlorine-containing solution may be no less than 1000 mg / L. Specifically, it may be 1000 to 2000 mg / L. The pH of the chlorine-containing wastewater or the chlorine-containing solution may be 5 to 8. When the chloride ion concentration is no less than 1000 mg / L, the adsorption capacity of chloride ions is significantly increased, thereby rapidly removing chloride ions and achieving rapid conversion of chloride ions to basic copper chloride. Therefore, the present invention also falls under the category of removing high-concentration chloride ions.

[0044] In the present invention, the copper electrode contains a copper material, and the mass proportion of the copper element in the copper material can be 20-70%, preferably 25-35%. As an implementation method, the copper electrode can be a working electrode prepared from copper particles or nano-copper powder; for example, the copper material can include or be a coating material, and the coating material can include copper powder and a binder, that is, the copper electrode can contain a current collector and a coating material, and the current collector can be composed of an inert material. The current collector used in the embodiment of the present invention is a titanium plate; since the coating material usually contains the binder, the binder can include or be one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and sodium carboxymethyl cellulose (CMC). In order to achieve the removal of chloride ions, the mass proportion of the copper element in the coating material can be 20-70%; in order to ensure the generation of basic copper chloride and achieve high-value removal of chloride ions in the chlorine-containing wastewater, the mass proportion of the copper element in the coating material can be 25-35%. As another implementation manner, the copper material may include or be at least one of copper foil, copper plate, and copper rod, and the mass proportion of the copper element may be 20-70%, preferably 25-35%.

[0045] As a specific illustration of the electrochemical reaction, during the chloride ion removal process, the applied voltage affects the chloride ion removal efficiency and the formation of basic copper chloride. To increase the adsorption of chloride ions and ensure the formation of basic copper chloride, the applied voltage is 1.0-1.4 V. Furthermore, the electrochemical reaction can last for 20 to 90 minutes.

[0046] As an illustration of the capacitive deionization device, the capacitive deionization device may be a two-electrode system; the cathode of the capacitive deionization device may be an activated carbon electrode; and the capacitive deionization device has an internal chamber for electrochemical reaction.

[0047] It should be pointed out that the present invention uses elemental copper as the active ingredient of the working electrode. According to the Cu-Cl-H2O system potential-pH diagram, the solution pH is controlled and the electrode potential is regulated to obtain basic copper chloride (Cu2(OH)3Cl), but there is no relevant technical report yet. The price of Cu is slightly lower than that of Cu2(OH)3Cl. In 2018, the price of Cu was 46,000 yuan / ton, while the price of Cu2(OH)3Cl was 50,000 yuan / ton. Secondly, the existing chloride ion recovery is mainly used to prepare sodium chloride products. The price of sodium chloride is 50,000 yuan / ton, while the price of Cu2(OH)3Cl is 50,000 yuan / ton. Therefore, preparing a high-concentration chloride ion solution as Cu2(OH)3Cl can realize chloride ion open circuit and high value.

[0048] In addition, Cu2(OH)3Cl is a high-value product with a wide range of uses. It is often used as a basic raw material for the manufacture of other copper salt products, pesticide intermediates, pharmaceutical intermediates, agricultural fungicides, wood preservatives, feed additives, etc. At the same time, the potential difference of the electrochemical process cannot exceed the standard electrode potential (E cell Φ =-1.23V), and no other ions can undergo polarization reactions during the electrochemical process. Therefore, the electrochemical process requires very little energy, which can achieve low-cost chloride ion removal and high value.

[0049] The following are specific examples of the present invention:

[0050] Example 1

[0051] A copper electrode (CuNPs-15) was prepared by the following method: 15 mg of nano-copper powder was evenly mixed with 35 mg of a binder (polyvinylidene fluoride) to obtain a coating material; the coating material was transferred to a mortar and ground, 200 μL of N-methylpyrrolidone was added to prepare a slurry, and then single-sided coating was applied to a 6 cm*6 cm current collector and vacuum-dried at 50°C for 12 hours; in this embodiment, the copper content of the copper electrode was 30% (the mass proportion of copper powder in the coating material).

[0052] A copper electrode (CuNPs-20) was prepared by the following method: 20 mg of nano-copper powder was evenly mixed with 30 mg of a binder (polyvinylidene fluoride) to obtain a coating material; the coating material was transferred to a mortar and ground, 200 μL of N-methylpyrrolidone was added to prepare a slurry, and then single-sided coating was applied to a 6 cm*6 cm current collector and vacuum-dried at 50°C for 12 hours; in this embodiment, the copper content of the copper electrode was 40% (the mass proportion of copper powder in the coating material).

[0053] A copper electrode (CuNPs-30) was prepared by the following method: 30 mg of nano-copper powder was evenly mixed with 20 mg of a binder (polyvinylidene fluoride) to obtain a coating material; the coating material was transferred to a mortar and ground, 200 μL of N-methylpyrrolidone was added to prepare a slurry, and then single-sided coating was applied to a 6 cm*6 cm current collector and vacuum-dried at 50°C for 12 hours; in this embodiment, the copper content of the copper electrode was 60% (the mass proportion of copper powder in the coating material).

[0054] A copper electrode (CuNPs-45) was prepared by the following method: 45 mg of nano-copper powder was evenly mixed with 5 mg of a binder (polyvinylidene fluoride) to obtain a coating material; the coating material was transferred to a mortar and ground, 200 μL of N-methylpyrrolidone was added to prepare a slurry, and then single-sided coating was applied to a 6 cm*6 cm current collector and vacuum-dried at 50°C for 12 hours; in this embodiment, the copper content of the copper electrode was 90% (the mass proportion of copper powder in the coating material).

[0055] The activated carbon electrode was prepared by the following method: 40 mg of activated carbon, 5 mg of conductive carbon black, and 5 mg of polyvinylidene fluoride were weighed, mixed evenly, and then transferred to a mortar for grinding. 200 μL of N-methylpyrrolidone was added to prepare a slurry, which was then coated on one side onto a 6 cm*6 cm current collector and vacuum dried at 50°C for 12 hours.

[0056] Example 2

[0057] CuNPs-15, CuNPs-20, CuNPs-30, and CuNPs-45 in Example 1 were used as test materials for electrochemical tests.

[0058] The specific test process is:

[0059] 1. Preparation of salt solution: Dissolve NaCl solid powder in a beaker and transfer to a volumetric flask to make up the volume; - The initial concentration of was 1000 mg / L, and the initial pH of the salt solution was 6;

[0060] 2. The material to be tested is used as the anode of a capacitive deionization device (with the coated surface facing the cathode), and the activated carbon electrode in Example 1 is used as the cathode of the capacitive deionization device (with the coated surface facing the anode); the capacitive deionization device in this example is a two-electrode system;

[0061] 3. Add 40 ml of the above salt solution to the capacitive deionization device and apply a voltage of 1.0 V (working electrode potential) for 1 hour.

[0062] Test results:

[0063] See also Figure 1As shown, the Cl of CuNPs-15 - The removal effect corresponds to the Cl removal of 15mg and CuNPs-20 in the figure. - The removal effect corresponds to the Cl removal of 20mg and CuNPs-30 in the figure. - The removal effect corresponds to the Cl removal of 30mg and CuNPs-45 in the figure. - The removal effect corresponds to 45 mg in the figure.

[0064] Reference Figure 1 To understand, different Cu content has an effect on Cl - Specifically, copper electrodes with copper contents of 15 mg (30%), 20 mg (40%), 30 mg (60%), and 45 mg (90%) were used for desalination. After 1 hour of chlorine removal, Cl - The equilibrium adsorption capacities are 90.4 mg / g, 101.2 mg / g, 97.9 mg / g, and 46.7 mg / g.

[0065] The physical phase of the anode electrode material after the reaction (excluding the current collector) is shown in Figure 2 As shown, it can be seen that when the copper content of the copper electrode is 30%, the diffraction peak of Cu2(OH)3Cl appears in the product after the reaction.

[0066] When the copper content is 40% or 60%, although there is a removal effect, it is found from the XRD diagram that the product at this time is mainly Cu2O, so the copper content in the electrode must be controlled.

[0067] Example 3

[0068] Compared with Example 2, this example limits the material to be tested to CuNPs-15 in Example 1, and sets the voltage to 0.6 V, 0.8 V, and 1.4 V, respectively (each voltage is a separate electrochemical test). Other conditions are consistent with Example 2 to analyze the effects of different voltages on the test results.

[0069] Combined with the data corresponding to 1.0V in Example 2, see Figure 3 It can be seen that when the voltage is 0.6V, 0.8V, 1.0V, and 1.4V, respectively, after 1h of reaction, the equilibrium adsorption amounts are 35.6mg / g, 48.6mg / g, 90.4mg / g, and 85.1mg / g, respectively.

[0070] The physical phase of the anode electrode material after the reaction (excluding the current collector) is shown in Figure 4 As shown, it can be seen that when the copper content of the copper electrode is 30% and the voltage is 1.0-1.4 V, the adsorption amount is high, and the products after the reaction all show the diffraction peak of Cu2(OH)3Cl.

[0071] Example 4

[0072] Compared with Example 2, this example limits the material to be tested to CuNPs-15 in Example 1, and the Cl in the salt solution is - The initial concentration (NaCl concentration) was set to 100 mg / L, 500 mg / L, and 2000 mg / L (each concentration was a separate test), and other conditions were consistent with Example 2 to analyze the effects of different concentrations on the test results.

[0073] Combined with the data corresponding to 1000 mg / L in Example 2, see Figure 5 Understand, we can see: Cl - When the initial concentrations were 100 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L, respectively, after 1 h of reaction, the equilibrium adsorption capacities were 30.2 mg / g, 44.6 mg / g, 90.4 mg / g, and 138.4 mg / g, respectively.

[0074] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing basic copper chloride, characterized in that: include: placing a chlorine-containing solution in a capacitive deionization device for electrochemical reaction, wherein the anode of the capacitive deionization device is a copper electrode; The copper electrode contains copper material, and the mass proportion of copper element in the copper material is 25-35%; the external voltage of the electrochemical reaction is 1.0-1.4V.

2. The preparation method of basic copper chloride according to claim 1, wherein The concentration of chloride ions in the chlorine-containing solution is not less than 1000 mg / L.

3. The preparation method of basic copper chloride according to claim 1, wherein The pH of the chlorine-containing solution is 5-8.

4. The preparation method of basic copper chloride according to claim 1, wherein The copper material includes a coating material, and the coating material includes copper powder and a binder.

5. The preparation method of basic copper chloride according to claim 4, wherein The binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, and sodium carboxymethyl cellulose.

6. The method for preparing basic copper chloride according to claim 1, wherein The copper material includes at least one of copper foil, copper plate, and copper rod.

7. The method for preparing basic copper chloride according to claim 1, wherein The duration of the electrochemical reaction is 20 to 90 minutes.

8. The method for preparing basic copper chloride according to any one of claims 1 to 7, wherein The cathode of the capacitive deionization device is an activated carbon electrode.

Images