A catalyst with slow-release chloride ion function and its preparation method and application

Abstract

The application discloses a catalyst with slow-release chloride ion function and a preparation method and application thereof, and belongs to the technical field of catalysts and wastewater treatment. The catalyst is a shell-core structure particle catalyst NiFe@NC-Cl prepared by combining nickel-iron nanoparticles and chloride ions in high-chlorine wastewater with nitrogen-doped carbon wrapped by low-viscosity sodium carboxymethyl cellulose. The catalyst has the characteristics of slow-release chloride ions triggered by dissolution, so when the catalyst activates PMS, the chloride ions locally released by the catalyst in water first react with PMS to generate O2 and free chlorine, oxidize organic pollutants, and NiFe@NC can further activate PMS to generate sulfate radicals (SO4 1 ·), oxidize organic pollutants, improve the degradation capacity of organic pollutants, and realize efficient degradation of organic pollutants in wastewater. ‑ ·).

Description

Technical Field

[0001] This application belongs to the field of catalyst and wastewater treatment technology, specifically relating to a catalyst with slow-release chloride ion function, its preparation method and application. Background Technology

[0002] High-chlorine wastewater refers to industrial wastewater with a chloride ion concentration exceeding 3 g / L. This wastewater contains high concentrations of sodium chloride or potassium chloride and primarily originates from industries such as leather tanning, pickling, salt production, petrochemicals, and seafood canning. Although my country's *Integrated Wastewater Discharge Standard (GB 8978-1996)* does not specify limits on chloride discharge, the *Water Quality Standard for Wastewater Discharge into Urban Sewerage Systems (GB / T 31962-2015)* does, stipulating a maximum allowable concentration of 500 mg / L for direct chloride ion discharge. Furthermore, some provinces have implemented even higher limits on chloride ion discharge concentrations; for example, the *Hebei Province Chloride Discharge Standard (DB 13 / 813-2006)* and the *Liaoning Province Integrated Wastewater Discharge Standard (DB21 / 1627-2008) both stipulate a maximum allowable concentration of 400 mg / L for direct chloride ion discharge.

[0003] Chloride ions are highly corrosive and hinder the growth of aquatic animals and plants, causing serious damage to the ecological environment. Chloride ions are the most stable form of chlorine; microorganisms cannot utilize chlorine, and in wastewater, chloride ions inhibit microbial growth. In practice, it has been found that when using biological methods to treat wastewater, the biological treatment efficiency significantly decreases when the chloride salt content in the wastewater exceeds 3% by mass.

[0004] Methods for removing chloride ions from high-chloride wastewater containing sodium chloride or potassium chloride mainly include precipitation, membrane separation, and evaporation concentration. However, because chloride ions can form soluble salts with most metal ions, precipitation is generally difficult to apply. Silver ions can precipitate chloride ions, but they are expensive and difficult to use on a large scale. Cuprous ions can also precipitate chloride ions, thus removing them from the water, but they are easily oxidized and costly, making industrial application difficult. Membrane separation can remove chloride ions from water, but most high-concentration chloride wastewater exceeds the application limits of membrane technology. Furthermore, other components in the wastewater can cause irreversible fouling of the membrane modules, limiting its application in this field. Evaporation concentration is effective in treating high-chloride wastewater containing sodium chloride or potassium chloride, but it requires highly corrosion-resistant equipment, and due to the high specific heat of water, evaporation energy consumption is high, leading to high operating costs.

[0005] Therefore, it is extremely important to know how to treat high-chlorine wastewater or to find a way to utilize high-chlorine wastewater as a resource. Summary of the Invention

[0006] 1. Purpose of the invention

[0007] To address the problems existing in current methods for removing chloride ions from high-chlorine wastewater, this application provides a catalyst with slow-release chloride ion function, its preparation method, and its application. The catalyst, NiFe@NC-Cl, is prepared using sodium chloride or potassium chloride from high-chlorine wastewater as a raw material. This catalyst has the function of efficiently activating permonosulfate (PMS), maximizing the utilization of chloride ions in high-chlorine wastewater, and achieving emission reduction and reuse of high-chlorine wastewater containing sodium chloride or potassium chloride.

[0008] 2. Technical Solution

[0009] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0010] This application provides a method for preparing a catalyst with a slow-release chloride ion function. The method involves using low-viscosity sodium carboxymethyl cellulose to encapsulate nitrogen-doped carbon-coated nickel-iron nanoparticles and combine them with chloride ions from high-chlorine wastewater to prepare a core-shell structured particle catalyst, NiFe@NC-Cl. This catalyst exhibits a slow-release chloride ion characteristic triggered by dissolution. Therefore, when this catalyst activates PMS, the chloride ions locally released by the catalyst upon contact with water first react with the PMS to generate chloride ions. 1 O2 and free chlorine oxidize organic pollutants. After the chloride ions are released, NiFe@NC can further activate PMS to generate sulfate radicals (SO4). - •), oxidize organic pollutants, improve the degradation capacity of organic pollutants, and achieve efficient degradation of organic pollutants in wastewater.

[0011] Furthermore, the preparation method of the above-mentioned catalyst with slow-release chloride ion function specifically includes the following steps:

[0012] S1, NiFe@NC nickel-iron nanoparticles coated with nitrogen-doped carbon are mixed with high-chlorine wastewater, stirred, dried and ground to obtain homogeneous powder;

[0013] S2, mix the homogeneous powder in S1 with low-viscosity sodium carboxymethyl cellulose, stir and mix well to obtain a viscous liquid;

[0014] S3, solidify and shape the viscous liquid in S2 to obtain the catalyst NiFe@NC-Cl with the function of slow-release chloride ions.

[0015] Furthermore, in S1 above, the nitrogen-doped carbon-encapsulated nickel-iron nanoparticles NiFe@NC are prepared using a simple pyrolysis method, specifically including the following steps:

[0016] S11, add dicyandiamine, nickel chloride hexahydrate and ferrous chloride tetrahydrate to a methanol solution and stir continuously until the solution is clear; dry the clear solution and grind it to obtain a homogeneous powder;

[0017] S12, the homogeneous powder is heated to 450-550℃ in a nitrogen atmosphere at a rate of 2-5℃ / min and held at the temperature for 2-3 hours; then heated to 700-800℃ and held at the temperature for 2-3 hours; after the reaction is completed, it is cooled to room temperature in a nitrogen atmosphere to obtain a black powder.

[0018] S13, the obtained black powder is placed in sulfuric acid solution and ultrasonically treated; then it is placed in a shaker for treatment, and the precipitate is washed with water multiple times until the washing solution is neutral, separated and dried to obtain the target product nitrogen-doped carbon-encapsulated nickel-iron nanoparticles (NiFe@NC).

[0019] Furthermore, in S11 above, relative to 100 mL of methanol solution, the amount of dicyandiamine is 2-5 g, the amount of nickel chloride hexahydrate is 0.24-0.6 g, and the amount of ferrous chloride tetrahydrate is 0.16-0.42 g.

[0020] Furthermore, in S11 above, the stirring includes stirring at a speed of 350-450 r / min for 1-3 hours at 50°C.

[0021] Furthermore, in S11 above, drying includes drying at 80±5 degrees Celsius for 24 to 40 hours.

[0022] Furthermore, in S12 above, the flow rate of nitrogen is 0.1 mL / min.

[0023] Furthermore, in S13 above, the concentration of the sulfuric acid solution is 0.5 mol / L.

[0024] Furthermore, in S13 above, the ultrasonic treatment includes: a power of 40 kHz and a time of 1 to 2 hours.

[0025] Furthermore, in S13 above, the treatment in the shaking table includes treatment at 50-55°C and 150-200 rpm for 24-30 hours.

[0026] Furthermore, in S13 above, drying includes drying at 80±5 degrees Celsius.

[0027] Furthermore, in S1 above, the concentration of chloride ions in the high-chlorine wastewater is not less than 3 to 6 g / L.

[0028] Furthermore, in S1 above, the high-chlorine wastewater mainly includes sodium chloride and / or potassium chloride.

[0029] Furthermore, in the above-mentioned S1, high-chlorine wastewater includes wastewater from leather tanning, pickling, salt production, petrochemicals, and seafood canning.

[0030] Furthermore, in S1 above, the chloride content in the high-chlorine wastewater is not less than 5g relative to 1gNiFe@NC.

[0031] Furthermore, in S1 above, the stirring includes stirring at a speed of 400-500 r / min for 2-8 hours.

[0032] Furthermore, in S1 above, drying includes drying at 80±5 degrees Celsius.

[0033] Furthermore, in the above S2, the low-viscosity sodium carboxymethyl cellulose has the following properties: viscosity: 300–600 Cps (12% Brookfield, GB1904-2005), degree of substitution: 1.15–1.45 (GB 1904-2005), purity: >99.5% (ASTM D1493-03), pH value: 6.5–8.5 (GB 1904-2005), moisture content: <8% (GB 1904-2005), and particle size: >99% (180 micrometers, passing through an 80-mesh standard sieve).

[0034] Furthermore, in S2 above, the amount of low-viscosity sodium carboxymethyl cellulose is 3 to 5 g relative to 1 g of homogeneous powder.

[0035] Furthermore, in S2 above, the dissolution rate of the catalyst is controlled by adjusting the degree of alcoholysis and polymerization of low-viscosity sodium carboxymethyl cellulose.

[0036] Furthermore, in S2 above, the stirring includes stirring at a speed of 100-800 r / min for 0.5-3.5 hours.

[0037] Furthermore, in S3 above, the curing and shaping includes fixing the viscous liquid into a sheet-like catalyst.

[0038] Furthermore, in S3 above, the thickness of the slow-release chloride ion sheet catalyst is controlled within the range of 5 to 10 mm, and the dissolution rate can be arbitrarily adjusted within the range of 20 hours to 20 days.

[0039] Furthermore, in S3 above, the curing and shaping are carried out through a curing and shaping mold. Specifically, a catalyst curing and shaping mold is prepared, a viscous liquid is injected into the bottom of the curing and shaping mold, and curing and shaping are carried out to obtain a sheet-like NiFe@NC-Cl catalyst with the function of slow-release chloride ions.

[0040] This application also provides a slow-release chloride ion catalyst prepared by the above-mentioned method for preparing a catalyst with slow-release chloride ion function.

[0041] This application also provides the application of the above-mentioned catalyst with slow-release chloride ion function in the treatment of wastewater for the efficient activation of permonosulfate (PMS).

[0042] Furthermore, the above applications include the degradation of organic pollutants in dye wastewater, especially recalcitrant organic matter.

[0043] Furthermore, the above applications include using a slow-release chloride ion catalyst to activate persulfate (PMS) and degrade recalcitrant organic pollutants in dye wastewater.

[0044] Furthermore, the aforementioned dyes include, but are not limited to, Golden Orange II, Rhodamine B, and Methylene Blue.

[0045] Furthermore, the above applications include dispersing the NiFe@NC-Cl catalyst into a wastewater solution, and after adsorption-desorption equilibrium is reached, adding persulfate to initiate the degradation reaction.

[0046] Furthermore, the above applications include the degradation of Orange II, which involves dispersing 0.005–0.03 g of NiFe@NC-Cl catalyst into 500 mL of a 20 mg / L Orange II solution, and after reaching adsorption-desorption equilibrium in 60 min, adding 0.1–1 g / L of persulfate to initiate the degradation reaction.

[0047] 3. Beneficial effects

[0048] Compared with the prior art, the advantages of this application are as follows:

[0049] (1) This application provides a catalyst NiFe@NC-Cl with slow-release chloride ion function, its preparation method and application. The catalyst can slowly release chloride ions during the application process. During the slow release of chloride ions, it can indirectly oxidize persulfate (PMS) to generate a large amount of singlet oxygen, thereby degrading organic pollutants in wastewater in a short time.

[0050] (2) This application provides a catalyst NiFe@NC-Cl with slow-release chloride ion function, its preparation method and application. The catalyst has the advantages of high singlet oxygen generation, good treatment effect, convenient operation, low cost, long-term use, recyclability and clean safety, providing a new idea for the degradation of organic matter.

[0051] (3) The catalyst NiFe@NC-Cl with the function of slow-release chloride ions provided in this application, its preparation method and application, provide a feasible method for the resource utilization of high-chlorine wastewater containing sodium chloride or potassium chloride without increasing operating costs. The chloride ions are made into the catalyst NiFe@NC-Cl, which has the function of highly activating PMS, so as to maximize the utilization of chloride ions in high-chlorine wastewater containing sodium chloride or potassium chloride, and realize the reduction and reuse of high-chlorine wastewater containing sodium chloride or potassium chloride.

[0052] (4) This application provides a catalyst NiFe@NC-Cl with a slow-release chloride ion function, its preparation method, and its application. As shown in the examples, the catalytic degradation effect of NiFe@NC-Cl is better than that of NiFe@NC. This catalyst has the characteristic of slow-release chloride ions triggered by dissolution. Therefore, when the catalyst activates PMS, the chloride ions locally released by the catalyst upon contact with water first react with PMS to generate chloride ions. 1 O2 and free chlorine oxidize organic pollutants, and NiFe@NC can further activate PMS to generate sulfate radicals (SO4). - •), oxidizes organic pollutants, avoiding the reaction of chloride ions with sulfate free radicals (SO4). - The effect of ·) can improve the degradation capacity of organic pollutants and achieve efficient degradation of organic pollutants in wastewater. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the NiFe@NC preparation process.

[0054] Figure 2 This is a schematic diagram of the preparation process of NiFe@NC-Cl.

[0055] Figure 3 This is the X-ray diffraction (XRD) pattern of the NiFe@NC-Cl sample prepared in Example 1.

[0056] Figure 4 This is a transmission electron microscope (TEM) image of the NiFe@NC-Cl sample prepared in Example 1.

[0057] Figure 5 This is a transmission electron microscope (TEM) image of the NiFe@NC-Cl sample prepared in Example 1.

[0058] Figure 6 This is a schematic diagram of the reaction principle of the NiFe@NC-Cl catalyst.

[0059] Figure 7 The results show the degradation of golden orange II by PMS activated by NiFe@NC-Cl and NiFe@NC catalysts.

[0060] Figure 8 This is a graph showing the cyclic degradation effect of the NiFe@NC-Cl catalyst. Detailed Implementation

[0061] The present application will be further described below with reference to specific embodiments.

[0062] It should be noted that terms such as "upper", "lower", "left", "right", and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of this application.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0064] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0065] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0066] As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B, and C” explicitly includes only A, only B, only C, and combinations thereof.

[0067] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as “less than about 4.5,” which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0068] Example 1

[0069] This embodiment provides a catalyst NiFe@NC-Cl with a slow-release chloride ion function and its preparation method. The preparation process is as follows: Figures 1-2 As shown, the specific steps include the following:

[0070] (1) Preparation of nitrogen-doped carbon-encapsulated nickel-iron nanoparticles (NiFe@NC)

[0071] Nitrogen-doped carbon-coated nickel-iron nanoparticles were prepared by a simple pyrolysis method. 10.09 g (120 mmol) of dicyandiamine, 1.222 g (4.2 mmol) of nickel chloride hexahydrate and 0.835 g (4.2 mmol) of ferrous chloride tetrahydrate were weighed and added to a beaker containing 300 mL of methanol solution. The mixture was stirred continuously at 50 °C and 350 r / min for 1 hour until the solution became clear and a homogeneous solution was obtained.

[0072] The homogeneous clear solution was dried in an oven at 80°C for 30 hours and then ground with an agate mortar to obtain a homogeneous powder.

[0073] The homogeneous powder was placed in a quartz boat, and the quartz boat was placed in the uniform temperature zone of a tube furnace. The temperature was increased to 500°C at a rate of 5°C / min in a nitrogen atmosphere with a flow rate of 0.1 mL / min, and held at that temperature for 2 hours. The temperature was then increased to 700°C and held at that temperature for 2 hours. After the reaction was completed, the quartz tube was cooled to room temperature in a nitrogen atmosphere to obtain a black powder.

[0074] The obtained black powder was placed in a beaker, and 100 mL of 0.5 mol / L sulfuric acid solution was added and sonicated (40 kHz) for 1 hour; then it was placed in a shaker for 24 hours (T = 50 °C, r = 180 rpm).

[0075] The precipitate was then washed repeatedly with water until the washing solution was neutral, separated, and dried at 80°C to obtain the target product, nitrogen-doped carbon-encapsulated nickel-iron nanoparticles (NiFe@NC).

[0076] (2) Preparation of homogeneous mixed powder

[0077] Weigh 0.1g of the NiFe@NC prepared in step (1) and place it in a 200mL beaker. Then add 100mL of high-chlorine wastewater with a sodium chloride concentration of 6g / L to the beaker. At this time, the mass ratio of NiFe@NC to NaCl is 1:6. Stir at 450r / min for 4 hours, dry at 80℃, and grind to obtain a homogeneous mixed powder.

[0078] (3) Preparation of a slow-release chloride ion functionalized sheet catalyst (NiFe@NC-Cl)

[0079] The homogeneous mixed powder obtained in step (2) and low-viscosity sodium carboxymethyl cellulose (viscosity: 300-600 Cps (12% Brookfield, GB1904-2005), degree of substitution: 1.15-1.45 (GB 1904-2005), purity: >99.5% (ASTM D1493-03), pH value: 6.5-8.5 (GB 1904-2005), moisture: <8% (GB 1904-2005), particle size: >99% (180 micrometers, passing rate of 80 mesh standard sieve) were mixed at a mass ratio of 0.3:1 and stirred at 200 r / min for 2 hours to obtain a viscous liquid;

[0080] A viscous liquid is injected into the bottom of a catalyst curing mold for curing and shaping, resulting in a slow-release chloride ion functional sheet catalyst (NiFe@NC-Cl) with a sheet thickness controlled in the range of 5-10 mm and a dissolution rate of 20 hours to 20 days.

[0081] Results analysis:

[0082] Figure 3 This is the X-ray diffraction (XRD) pattern of the NiFe@NC-Cl sample prepared in this embodiment. From... Figure 3 As can be seen, the sample has a diffraction peak at 2θ = 26.2°, which is graphitic carbon with a crystal plane of (002), consistent with the structural characteristics of carbon nanotubes. The other diffraction peaks correspond to elemental iron (JCPDS no. 89-7194) and elemental nickel (JCPDS no. 70-1849) with a face-centered cubic crystal structure and a high degree of metal crystallization. Meanwhile, the three diffraction peaks at 44.3°, 51.5°, and 75.9° can identify the (111), (200), and (220) planes of the typical FeNi3 alloy (JCPDS PDF#38-0419) structure.

[0083] Figure 4 and Figure 5 This is a transmission electron microscope (TEM) image of the NiFe@NC-Cl sample prepared in this embodiment. From... Figure 4 As can be seen, the NiFe@NC-Cl catalyst is mainly composed of Cl, Na, Ni, and Fe elements. The overlapping presence of nickel and iron fully demonstrates that the nickel-iron alloy is encapsulated by a carbon layer, rather than being loaded into the carbon nanotubes through simple geometric interactions. In addition to abundant Cl and Na, the presence of NiFe alloy was also observed in the in-situ grown carbon nanotubes. Figure 5 This indicates that Ni and Fe in NiFe@NC-Cl not only coordinate with the surrounding Cl to form NiFe-Cl sites, but also catalyze the growth of carbon nanotubes and produce a large amount of NiFe alloy.

[0084] Example 2

[0085] This embodiment provides an application of a catalyst (NiFe@NC-Cl) with a slow-release chloride ion function.

[0086] In this embodiment, NiFe@NC-Cl is the NiFe@NC-Cl prepared in Example 1. Its application in activating PMS to degrade Golden Orange II specifically includes the following steps:

[0087] Take two 1000mL beakers and add 500mL of 20mg / L Orange II solution to each;

[0088] Weigh 0.01 g of the NiFe@NC-Cl and NiFe@NC catalysts prepared in Example 1 and add them to a beaker. Place the solution in a magnetic stirrer (room temperature, 420 r / min) for reaction.

[0089] After adsorption-desorption equilibrium was reached after 60 min, 0.4 g / L PMS was added to initiate the degradation reaction. Samples were taken at 0, 2, 4, 6, 8, 10, 15, 20, 30, 40, 50, and 60 min. The samples were filtered through a 0.22 μm aqueous filter and 2 mL of solution was collected. Then, 2 mL of methanol (analytical grade) was added to quench the oxidation reaction. Finally, the absorbance of the solution at 484 nm was measured using a UV spectrophotometer to plot the degradation curve.

[0090] Results analysis:

[0091] Figure 6 This is a schematic diagram illustrating the reaction principle of the NiFe@NC-Cl catalyst. The NiFe@NC-Cl catalyst dissolves in water, slowly releasing small amounts of chloride, sodium, and potassium ions.

[0092] The results of PMS degradation of Orange II activated by NiFe@NC-Cl and NiFe@NC catalysts are as follows: Figure 7 As shown, Figure 7 (a) is a comparison of the effects of NiFe@NC-Cl and NiFe@NC catalysts on the degradation of PMS for Orange II. It can be seen that the degradation effect of NiFe@NC-Cl catalyst on Orange II is significantly better than that of NiFe@NC catalyst. Figure 7 (b) and Figure 7 (c) shows the results of the reaction kinetic fitting of the degradation process. Both catalysts conform to pseudo-first-order kinetics, and the reaction rate constants k for NiFe@NC-Cl and NiFe@NC catalysts are 0.1516 and 0.0397 min, respectively. -1 .

[0093] The simple recovery method and excellent reusability of the catalyst can effectively reduce the cost of wastewater treatment. In this embodiment, the used NiFe@NC-Cl catalyst will also be recovered by filtration, dried, and regenerated before reuse. Figure 8 The changes in the catalytic efficiency of the catalyst over three cycles were shown, revealing that the catalytic efficiency of the regenerated catalyst remained almost unchanged, which can effectively reduce the cost of wastewater treatment.

Claims

1. A method for preparing a catalyst with a slow-release chloride ion function, characterized in that, The method involves using low-viscosity sodium carboxymethyl cellulose to encapsulate nitrogen-doped carbon nickel-iron nanoparticles and combine them with chloride ions in high-chlorine wastewater to prepare a core-shell structured catalyst. The method includes the following steps: S1, Nitrogen-doped carbon-encapsulated nickel-iron nanoparticles are mixed with high-chlorine wastewater, stirred, dried and ground to obtain homogeneous powder; S2, mix the homogeneous powder from S1 with low-viscosity sodium carboxymethyl cellulose, stir and mix well to obtain a viscous liquid; the viscosity of the low-viscosity sodium carboxymethyl cellulose is 300~600 Cps; S3, solidify and shape the viscous liquid in S2 to obtain the NiFe@NC-Cl catalyst with slow-release chloride ion function; In step S1, the preparation of nitrogen-doped carbon-encapsulated nickel-iron nanoparticles specifically includes the following steps: S11, add dicyandiamine, nickel chloride hexahydrate and ferrous chloride tetrahydrate to a methanol solution and stir continuously until the solution is clear; dry the clear solution and grind it to obtain a homogeneous powder; S12, the homogeneous powder is heated to 450-550 ℃ in a nitrogen atmosphere at a rate of 2-5 ℃ / min and held at the temperature for 2-3 hours; then heated to 700-800 ℃ and held at the temperature for 2-3 hours; after the reaction is completed, it is cooled to room temperature in a nitrogen atmosphere to obtain a black powder. S13, the obtained black powder is placed in sulfuric acid solution and ultrasonically treated; then it is placed in a shaker for treatment, and the precipitate is washed with water multiple times until the washing solution is neutral, separated and dried to obtain the target product nitrogen-doped carbon-encapsulated nickel-iron nanoparticles.

2. The method for preparing a catalyst with sustained chloride ion release function according to claim 1, characterized in that, In S1, the chloride content in the high-chlorine wastewater is not less than 5 g relative to 1 g NiFe@NC.

3. The method for preparing a catalyst with sustained chloride ion release function according to claim 2, characterized in that, In S2, the degree of substitution of low-viscosity sodium carboxymethyl cellulose is 1.15~1.

45.

4. The method for preparing a catalyst with slow-release chloride ion function according to claim 3, characterized in that, In step S3, the solidification and shaping process includes fixing the viscous liquid into a sheet-like catalyst.

5. The method for preparing a catalyst with sustained chloride ion release function according to claim 4, characterized in that, In S3, the thickness of the sheet-like catalyst is controlled at 5~10 mm.

6. A catalyst with a slow-release chloride ion function, characterized in that, It is prepared by the method for preparing a catalyst with slow-release chloride ion function as described in any one of claims 1-5.

7. The application of the catalyst with slow-release chloride ion function as described in claim 6 in wastewater treatment, characterized in that, Used to activate persulfate.

8. The application according to claim 7, characterized in that, The application includes using a slow-release chloride ion catalyst to activate persulfate and degrade recalcitrant organic pollutants in dye wastewater.

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