Preparation method of catalyst for modifying manganese slag to activate persulfate and application thereof

Abstract

The application discloses a modified manganese slag catalyst for activating persulfate, and a preparation method and application thereof. The catalyst preparation method comprises the following steps: step one, the retrieved electrolytic manganese slag sample is dried, ground and polished into a uniform powder, and the uniform powder is prepared into an original electrolytic manganese slag powder by passing through a 100-mesh screen; step two, the original electrolytic manganese slag powder is mixed with deionized water and stirred to obtain a uniformly mixed electrolytic manganese slag suspension; step three, calcium oxide is added to the electrolytic manganese slag suspension and stirred to react, so that a fully reacted mixed solution is obtained; step four, the mixed solution is subjected to suction filtration and rinsing until the solution is neutral, and then the solution is dried; and step five, the electrolytic manganese slag catalyst is prepared by grinding and passing through a 100-mesh screen. The modified electrolytic manganese slag catalyst is used for activating persulfate, so that azo dyes represented by acid orange in water bodies can be fully degraded, the degradation rate is high, the preparation method is simple, the production cost is low, and the catalyst is beneficial to industrial popularization and use.

Description

Technical Field

[0001] This invention belongs to the fields of environmental engineering and materials science and technology, and specifically relates to a method for preparing a catalyst for activating persulfate with modified manganese slag and its application. Background Technology

[0002] Electrolytic manganese slag (EMR) is a major solid waste generated during the electrolytic production of metallic manganese. Its production is enormous and continuously increasing; China alone produces over 150 million tons of EMR annually. The main component of EMR is an acidic solid waste obtained from the reaction of manganese ore powder and sulfuric acid. The particles are typically smaller than 80 μm, with a high moisture content, and contain large amounts of manganese, ammonia, and heavy metals such as copper, lead, nickel, and zinc. Currently, due to technological limitations, landfilling / damming is the most common method for EMR disposal, which not only occupies land resources but also poses a serious threat to the environment. Large-scale accumulation of EMR not only wastes a significant amount of industrial raw materials but also requires substantial land use during storage. Furthermore, the leached harmful substances pollute the surrounding soil and water environments, posing a serious potential threat to the local ecosystem. Therefore, how to achieve the harmless treatment and disposal of electrolytic manganese slag and how to reuse EMR for resource recovery have become urgent industry problems that the electrolytic manganese metal industry needs to solve. Although various treatment technologies have been proposed, such as water leaching, acid leaching, and alkali treatment, shortcomings and problems still exist in terms of adsorption performance and cost. Therefore, exploring the harmless and resource-based utilization of electrolytic manganese slag is urgently needed.

[0003] Dye wastewater refers to wastewater containing pollutants such as dyes, auxiliaries, salts, and organic matter generated during the dyeing process. These dyes are characterized by their reluctance to degrade, high chroma, and strong polluting properties, posing a significant threat to human health and the environment. While numerous studies have utilized biochar as a treatment agent for dye wastewater, these approaches suffer from difficulties in solid-liquid separation and low treatment efficiency. However, advanced oxidation technology (EMR) using sulfate radicals generated from activated persulfate possesses strong oxidizing properties, making its application in removing high-concentration organic wastewater feasible. Furthermore, EMR, rich in iron and manganese ions, can activate persulfate without the need for further transition metal addition, generating sulfate radicals to oxidize and degrade high-concentration organic wastewater. This demonstrates considerable potential, as it can be used as an adsorbent or to prepare catalysts for pollutant degradation and removal, achieving "waste-to-waste treatment."

[0004] Therefore, the application of electrolytic manganese slag activated persulfate in high-concentration organic wastewater can not only realize the resource utilization of electrolytic manganese slag, reduce the cost of enterprise stockpiling and treatment, and reduce ecological pollution, but also broaden the application path of "green and low-carbon" high-concentration organic wastewater.

[0005] Currently, there are many research reports on the preparation of manganese slag-based catalysts and their application in organic wastewater treatment; however, these methods still have some problems.

[0006] For example, Chinese patent application number 202311025981.0 discloses a method for preparing a manganese slag-based catalyst and its application. Modified electrolytic manganese slag is prepared by reacting potassium permanganate, manganese slag, and potassium persulfate. The removal rates of rhodamine B and antibiotics are over 98% and 70%, respectively. Although this method shows good removal efficiency for rhodamine B, potassium permanganate is a potentially explosive substance, posing a certain degree of danger, and its high cost may prevent its commercialization and large-scale industrial application.

[0007] For example, Chinese patent application No. 202311748945.7 discloses a method and application for preparing denitrification catalysts by activating roasted electrolytic manganese slag with oxalic acid. The method involves adding oxalic acid to electrolytic manganese slag and then roasting it, which can achieve a nitrogen oxide removal rate of more than 50%. However, this method requires roasting at a temperature of 450-550℃, which results in high costs.

[0008] For example, Chinese patent application number 201611215237.7 discloses a method for the efficient resource utilization of electrolytic manganese slag, which uses an alkali melting-hydrothermal synthesis method to obtain zeolite products for use as water treatment adsorbents. However, this method uses an alkali melting temperature of 450–600℃, which results in high cost and energy consumption.

[0009] For example, Chinese patent application number 201910679732.0 discloses a method for preparing high-adsorption-capacity zeolite by microwave alkaline fusion activation of electrolytic manganese slag. This method involves heating manganese slag, electrolytic manganese anolyte, and sodium hydroxide under microwave conditions at 400–600°C. The resulting zeolite can be used as an adsorbent in water treatment. However, this method uses microwave alkaline fusion, which is energy-intensive and costly, making industrial application difficult. Summary of the Invention

[0010] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing a catalyst for activating persulfate in modified manganese slag and its application. This invention uses calcium oxide as the oxidant, which is less expensive than the potassium permanganate used in existing technologies. Furthermore, calcium oxide (or quicklime) is the most convenient and simple method for removing ammonia nitrogen from manganese slag through water washing. While removing residual ammonia nitrogen from the manganese slag, it also activates persulfate, generating highly reactive free radicals to degrade organic pollutants, achieving a synergistic effect of "killing two birds with one stone." In addition, this system has a broad spectrum of applications for organic wastewater, not targeting a single type of organic wastewater, thus having better applicability.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A method for preparing a catalyst for activating persulfate with modified manganese slag includes the following steps:

[0013] Step 1: First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Then, pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag powder.

[0014] Step 2: Mix the raw electrolytic manganese slag powder obtained in the previous step with deionized water in a certain proportion, and stir it on a magnetic stirrer to obtain a uniformly mixed electrolytic manganese slag suspension.

[0015] Step 3: Add a certain amount of calcium oxide to the above-mentioned uniformly mixed electrolytic manganese slag suspension, and continue to stir the mixture with a magnetic stirrer to obtain a fully reacted mixture.

[0016] Step 4: Filter the mixture obtained above and rinse it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C.

[0017] Step 5: Grind the dried solid with an agate mortar and pass it through a 100-mesh sieve to prepare the modified electrolytic manganese slag catalyst.

[0018] In this invention, the main raw material is electrolytic manganese slag, which contains iron, aluminum, and silicon, as well as trace amounts of manganese. The metal elements in the electrolytic manganese slag are precisely the metal elements that activate persulfate; therefore, it can serve as a highly efficient catalyst for persulfate. The preparation method of this invention includes drying and grinding in step one, mixing and reaction in steps two and three, and washing and drying in steps four and five. The operation is simple and the cost is low.

[0019] In step one of this invention, drying and grinding serve to mechanically activate the electrolytic manganese slag powder, providing more surface active sites, using electrolytic manganese slag powder as the raw material. In step two, mixing and stirring dissolve some manganese ions from the original electrolytic manganese slag into the solution, facilitating the reaction with calcium oxide in the next step. In step three, adding calcium oxide to the suspension and magnetically stirring increases the reaction between calcium oxide and manganese ions. Simultaneously, the combination of calcium oxide and water releases heat, further increasing the reaction rate. After the reaction in step three, on the one hand, the formation of internal pore structures in the electrolytic manganese slag powder is achieved, increasing the specific surface area of ​​the modified electrolytic manganese slag catalyst and thus increasing the number of active sites. On the other hand, the stable loading of active species iron and manganese effectively activates persulfate to generate strong oxidizing sulfate radicals (SO4-·), thereby effectively degrading organic pollutants.

[0020] The present invention further explains that in step one, the electrolytic manganese slag sample is dried in an oven at 60-85°C for 24-72 hours to remove the moisture remaining in the electrolytic manganese slag, and then ground into small pieces with an agate mortar.

[0021] The present invention further illustrates that, in step two, the solid-liquid ratio (kg:L) of the mixture of the original electrolytic manganese slag powder and deionized water is 0.1 to 0.5; and the stirring time of the electrolytic manganese slag suspension is 0.25 to 12 h.

[0022] The present invention further illustrates that, in step three, the addition ratio (kg:kg) of calcium oxide and raw electrolytic manganese slag is 0.1 to 0.6; and the stirring reaction time is 0.25 to 12 h.

[0023] The present invention also provides a modified electrolytic manganese slag catalyst prepared by the preparation method described above.

[0024] The present invention also provides an application of the modified electrolytic manganese slag catalyst as described above in a persulfate activation system for the degradation of organic dyes or antibiotic wastewater in water bodies.

[0025] The application of the modified electrolytic manganese slag catalyst in the persulfate activation system is further illustrated by the following specific application method: persulfate is added to water containing acid orange azo dyes to obtain a mixed solution, and then the modified electrolytic manganese slag catalyst is added. The mixture is stirred with a magnetic stirrer for 2-3 hours to complete the degradation of azo dyes in the water.

[0026] The application further illustrates that, in the water containing acid orange azo dyes, the amount of persulfate added is 0.5–2 mmol / L; and the amount of modified electrolytic manganese slag catalyst added is 0.25–2.00 g / L.

[0027] The application further illustrates that the concentration of Acid Orange in the water body containing the Acid Orange azo dye is 10–100 mg / L.

[0028] The application of the modified electrolytic manganese slag catalyst in the persulfate activation system further illustrates that the pH range of the organic dye or antibiotic wastewater is 3 to 11; during the degradation reaction, the temperature of the degradation reaction is 5 to 40°C, and the time of the degradation reaction is 5 to 30 minutes.

[0029] Advantages of this invention:

[0030] 1. The method for preparing the catalyst for activated persulfate by modified manganese slag of the present invention includes drying and grinding in step one, mixing and reaction in steps two and three, and washing and drying in steps four and five. The operation is simple and the cost is low.

[0031] 2. The modified electrolytic manganese slag catalyst of the present invention can efficiently activate persulfate to generate free radicals with high oxidizing power. It is simple to operate and highly feasible, thereby improving the efficiency of degrading organic pollutants.

[0032] 3. The modified electrolytic manganese slag catalyst of the present invention has good chemical stability, relatively fast preparation speed, good degradation effect, and can significantly reduce the cost of pollutant treatment.

[0033] 4. The modified electrolytic manganese slag catalyst of the present invention uses electrolytic manganese slag as the main raw material, which can realize the high-value resource utilization of electrolytic manganese slag and solve the pollution problem caused by the stockpiling of electrolytic manganese slag.

[0034] 5. The modified electrolytic manganese slag catalyst of the present invention uses calcium oxide as a modifier, which is commercially available and does not require self-production or secondary processing, resulting in low cost. In addition, it is harmless, non-toxic, and highly usable.

[0035] 6. The modified electrolytic manganese slag catalyst of the present invention uses calcium oxide as a modifier to increase the hardness of the modified electrolytic manganese slag, which makes it possible to directly granulate manganese slag and provides a basis for subsequent industrial applications.

[0036] 7. The modified electrolytic manganese slag catalyst of the present invention is applied to the degradation of organic pollutants by activated persulfate. It not only has high catalytic activity, resulting in high pollutant degradation efficiency, but also enables high-value resource utilization of electrolytic manganese slag solid waste. Attached Figure Description

[0037] Figure 1 SEM images of the original unmodified electrolytic manganese slag and the modified electrolytic manganese slag catalyst in Example 3 of the present invention;

[0038] Figure 2 This is a standard curve for the concentration of AO7 solution.

[0039] Figure 3 The graphs show the changes in the removal rate of Acid Orange 7 (AO7) by the modified electrolytic manganese slag catalysts of Examples 1-9 and Comparative Examples 1-2.

[0040] Figure 4 The graph shows the changes in the removal rate of Acid Orange 7 (AO7) by different systems;

[0041] Figure 5 The graph shows the change in the removal rate of Acid Orange 7 (AO7) by the modified electrolytic manganese slag catalyst of Example 3, which is a common anion-pairing catalyst.

[0042] Figure 6 The graph shows the effect of humic acid on the removal rate of Acid Orange 7 (AO7) by the modified electrolytic manganese slag catalyst of Example 3.

[0043] Figure 7 The graph shows the effect of different pH values ​​on the removal rate of Acid Orange 7 (AO7) by the modified electrolytic manganese slag catalyst in Example 3.

[0044] Figure 8This is a graph showing the change in the removal rate of other pollutants by the modified electrolytic manganese slag catalyst in Example 3. Detailed Implementation

[0045] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the embodiments of the present invention, unless specifically specified, the technical means used are conventional means well known to those skilled in the art.

[0047] Example 1

[0048] A method for preparing a catalyst for activating persulfate with modified manganese slag includes the following steps:

[0049] S1. First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag powder.

[0050] S2. Mix 5g of the original electrolytic manganese slag powder obtained in the previous step with 15mL of deionized water, and stir on a magnetic stirrer for 30min to obtain a uniformly mixed electrolytic manganese slag suspension.

[0051] S3. Add 2g of calcium oxide to the above-mentioned uniformly mixed electrolytic manganese slag suspension, and continue to stir the reaction with a magnetic stirrer for 60 minutes to obtain a fully reacted mixture.

[0052] S4. Filter the mixture obtained above and rinse it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C.

[0053] S5. The dried solid was ground in an agate mortar and passed through a 100-mesh sieve to prepare a modified electrolytic manganese slag catalyst.

[0054] Example 2

[0055] A method for preparing a catalyst for activating persulfate with modified manganese slag includes the following steps:

[0056] S1. First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag powder.

[0057] S2. Mix 5g of the original electrolytic manganese slag powder obtained in the previous step with 20mL of deionized water, and stir on a magnetic stirrer for 30min to obtain a uniformly mixed electrolytic manganese slag suspension.

[0058] S3. Add 2g of calcium oxide to the above-mentioned uniformly mixed electrolytic manganese slag suspension, and continue to stir the reaction with a magnetic stirrer for 60 minutes to obtain a fully reacted mixture.

[0059] S4. Filter the mixture obtained above and rinse it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C.

[0060] S5. The dried solid was ground in an agate mortar and passed through a 100-mesh sieve to prepare a modified electrolytic manganese slag catalyst.

[0061] Example 3

[0062] A method for preparing a catalyst for activating persulfate with modified manganese slag includes the following steps:

[0063] S1. First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag powder.

[0064] S2. Mix 5g of the original electrolytic manganese slag powder obtained in the previous step with 25mL of deionized water, and stir on a magnetic stirrer for 30min to obtain a uniformly mixed electrolytic manganese slag suspension.

[0065] S3. Add 2g of calcium oxide to the above-mentioned uniformly mixed electrolytic manganese slag suspension, and continue to stir the reaction with a magnetic stirrer for 60 minutes to obtain a fully reacted mixture.

[0066] S4. Filter the mixture obtained above and rinse it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C.

[0067] S5. The dried solid was ground in an agate mortar and passed through a 100-mesh sieve to prepare a modified electrolytic manganese slag catalyst.

[0068] like Figure 1 As shown in the figure, a represents the original electrolytic manganese slag powder obtained in Example S1 of this embodiment, and b represents the modified electrolytic manganese slag catalyst obtained in this embodiment. Figure 1 It can be seen that, compared with the original electrolytic manganese slag, the modified electrolytic manganese slag has a network nanostructure, which gives it a larger specific surface area, thereby providing more active sites for the catalyst reaction and giving it higher catalytic activity.

[0069] Example 4

[0070] A method for preparing a catalyst for activating persulfate with modified manganese slag includes the following steps:

[0071] S1. First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag powder.

[0072] S2. Mix 5g of the original electrolytic manganese slag powder obtained in the previous step with 25mL of deionized water, and stir on a magnetic stirrer for 30min to obtain a uniformly mixed electrolytic manganese slag suspension.

[0073] S3. Add 0.5g of calcium oxide to the above-mentioned uniformly mixed electrolytic manganese slag suspension, and continue to stir the mixture with a magnetic stirrer for 60 minutes to obtain a fully reacted mixture.

[0074] S4. Filter the mixture obtained above and rinse it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C.

[0075] S5. The dried solid was ground in an agate mortar and passed through a 100-mesh sieve to prepare a modified electrolytic manganese slag catalyst.

[0076] Example 5

[0077] A method for preparing a catalyst for activating persulfate with modified manganese slag includes the following steps:

[0078] S1. First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag powder.

[0079] S2. Mix 5g of the original electrolytic manganese slag powder obtained in the previous step with 25mL of deionized water, and stir on a magnetic stirrer for 30min to obtain a uniformly mixed electrolytic manganese slag suspension.

[0080] S3. Add 1g of calcium oxide to the above-mentioned uniformly mixed electrolytic manganese slag suspension, and continue to stir the mixture with a magnetic stirrer for 60 minutes to obtain a fully reacted mixture.

[0081] S4. Filter the mixture obtained above and rinse it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C.

[0082] S5. The dried solid was ground in an agate mortar and passed through a 100-mesh sieve to prepare a modified electrolytic manganese slag catalyst.

[0083] Example 6

[0084] A method for preparing a catalyst for activating persulfate with modified manganese slag includes the following steps:

[0085] S1. First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag powder.

[0086] S2. Mix 5g of the original electrolytic manganese slag powder obtained in the previous step with 25mL of deionized water, and stir on a magnetic stirrer for 30min to obtain a uniformly mixed electrolytic manganese slag suspension.

[0087] S3. Add 3g of calcium oxide to the above-mentioned uniformly mixed electrolytic manganese slag suspension, and continue to stir the mixture with a magnetic stirrer for 60 minutes to obtain a fully reacted mixture.

[0088] S4. Filter the mixture obtained above and rinse it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C.

[0089] S5. The dried solid was ground in an agate mortar and passed through a 100-mesh sieve to prepare a modified electrolytic manganese slag catalyst.

[0090] Example 7

[0091] A method for preparing a catalyst for activating persulfate with modified manganese slag includes the following steps:

[0092] S1. First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag powder.

[0093] S2. Mix 5g of the original electrolytic manganese slag powder obtained in the previous step with 25mL of deionized water, and stir on a magnetic stirrer for 30min to obtain a uniformly mixed electrolytic manganese slag suspension.

[0094] S3. Add 2g of calcium oxide to the above-mentioned uniformly mixed electrolytic manganese slag suspension, and continue to stir the mixture with a magnetic stirrer for 15 minutes to obtain a fully reacted mixture.

[0095] S4. Filter the mixture obtained above and rinse it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C.

[0096] S5. The dried solid was ground in an agate mortar and passed through a 100-mesh sieve to prepare a modified electrolytic manganese slag catalyst.

[0097] Example 8

[0098] A method for preparing a catalyst for activating persulfate with modified manganese slag includes the following steps:

[0099] S1. First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag powder.

[0100] S2. Mix 5g of the original electrolytic manganese slag powder obtained in the previous step with 25mL of deionized water, and stir on a magnetic stirrer for 30min to obtain a uniformly mixed electrolytic manganese slag suspension.

[0101] S3. Add 2g of calcium oxide to the above-mentioned uniformly mixed electrolytic manganese slag suspension, and continue to stir the mixture with a magnetic stirrer for 30 minutes to obtain a fully reacted mixture.

[0102] S4. Filter the mixture obtained above and rinse it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C.

[0103] S5. The dried solid was ground in an agate mortar and passed through a 100-mesh sieve to prepare a modified electrolytic manganese slag catalyst.

[0104] Example 9

[0105] A method for preparing a catalyst for activating persulfate with modified manganese slag includes the following steps:

[0106] S1. First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag powder.

[0107] S2. Mix 5g of the original electrolytic manganese slag powder obtained in the previous step with 25mL of deionized water, and stir on a magnetic stirrer for 30min to obtain a uniformly mixed electrolytic manganese slag suspension.

[0108] S3. Add 2g of calcium oxide to the above-mentioned uniformly mixed electrolytic manganese slag suspension, and continue to stir the mixture with a magnetic stirrer for 90 minutes to obtain a fully reacted mixture.

[0109] S4. Filter the mixture obtained above and rinse it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C.

[0110] S5. The dried solid was ground in an agate mortar and passed through a 100-mesh sieve to prepare a modified electrolytic manganese slag catalyst.

[0111] Comparative Example 1

[0112] The preparation method of the electrolytic manganese slag in Comparative Example 1 is as follows:

[0113] S1. First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Then, pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag.

[0114] Comparative Example 2

[0115] The preparation method of the electrolytic manganese slag in Comparative Example 2 is as follows:

[0116] S1. First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Then, pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag.

[0117] S2. Mix 5g of the original electrolytic manganese slag powder obtained in the previous step with 25mL of deionized water, and stir on a magnetic stirrer for 30min to obtain a uniformly mixed electrolytic manganese slag suspension.

[0118] S3. Filter the suspension obtained above and wash it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C.

[0119] S4. The dried solid was ground in an agate mortar and passed through a 100-mesh sieve to prepare a modified electrolytic manganese slag catalyst.

[0120] To further illustrate the effects of the present invention, the modified electrolytic manganese slag catalysts prepared in Examples 1-7 and Comparative Examples 1-2 were specifically tested below.

[0121] Application Example 1

[0122] Several Acid Orange 7 (AO7) solutions were prepared, with an AO7 concentration of 40 mg / L. Modified electrolytic manganese slag catalysts prepared in Examples 1-7 and Comparative Examples 1-2, with a catalyst concentration of 0.3 g / L, were added to the Acid Orange 7 (AO7) solutions and placed on a magnetic stirrer. The mixtures were reacted for 30 min to reach adsorption and desorption equilibrium. Potassium persulfate (PMS), with a PMS concentration of 1 mmol / L, was added at ambient temperature. 3 mL samples were taken at different time intervals (0, 5, 10, 15, 20, and 300 min), filtered through a cellulose acetate filter, and then mixed with 1 mL of MeOH for storage. The concentration of the samples was determined using a UV-Vis spectrophotometer at the absorption peak at 483 nm. All experiments were repeated three times, and the average value was taken to reduce experimental error and ensure accuracy.

[0123] It is worth noting that the persulfates in this invention include, but are not limited to, sodium persulfate, potassium persulfate, and ammonium persulfate.

[0124] The degradation effect was determined using a UV-Vis spectrophotometer. The method for plotting the AO7 concentration standard curve is as follows:

[0125] An AO7 solution with a concentration of 40 mg / L was prepared and diluted to concentrations of 1, 2, 5, 10, 15, and 20 mg / L, resulting in AO7 solutions with concentrations of 1, 2, 5, 10, 15, 20, and 40 mg / L. The absorbance of the AO7 solutions at different concentrations was measured using a UV-Vis spectrophotometer at the absorption peak of 483 nm. A linear fit was then performed between the measured absorbance and the concentration of the AO7 solution to obtain the desired absorbance. Figure 2 The standard curve of AO7 solution concentration is shown.

[0126] The degradation efficiency of AO7 is calculated according to the following formula 2.1:

[0127] E = (C0 – C) / C0 × 100%

[0128] In the formula, C0 represents the initial concentration of AO7 (mg / L), C represents the measured concentration of AO7 (mg / L), and E represents the degradation efficiency of AO7 (%).

[0129] The removal rates (%) of AO7 by each group of modified electrolytic manganese slag catalysts are shown in Table 1 and... Figure 3 As shown:

[0130] Table 1

[0131]

[0132] As shown in Table 1 and Figure 3 The test results show that the modification time and the amount of calcium oxide used have a significant impact on the final AO7 degradation results, as detailed below:

[0133] (1) In Examples 1-3, as the ratio (g:mL) of the original electrolytic manganese slag to deionized water decreased, the ability of the modified electrolytic manganese slag to catalyze the degradation of AO7 by PMS gradually increased. Considering the actual situation, the optimal ratio was selected as 1:5.

[0134] (2) Compared with Example 3, in Examples 4-6, as the ratio of calcium oxide to original electrolytic manganese slag increases, the ability of modified electrolytic manganese slag to catalyze the degradation of AO7 by PMS gradually increases. From an economic perspective, the optimal ratio of calcium oxide to original electrolytic manganese slag in modified electrolytic manganese slag (g:g) is 2:5.

[0135] (3) Compared with Example 3, the ability of modified electrolytic manganese slag to catalyze the degradation of AO7 by PMS gradually increases with the increase of reaction time. Considering the time cost, the reaction time of modified electrolytic manganese slag is 60 min.

[0136] Application Example 2

[0137] Prepare three AO7 solutions with an AO7 concentration of 40 mg / L. Take two portions of the modified electrolytic manganese slag catalyst from Example 3 and add them to the AO7 solutions respectively. Place them on a magnetic stirrer. The concentration of the modified electrolytic manganese slag catalyst is 0.3 g / L. React for 30 min to reach adsorption and desorption equilibrium. One sample is treated with PMS at ambient temperature (1 mmol / L), while the control sample is treated without PMS. Take the remaining AO7 solution, without adding modified electrolytic manganese slag, and only add PMS at ambient temperature (1 mmol / L), keeping other conditions unchanged.

[0138] Take 3 mL samples at different time intervals (0, 5, 10, 15, 20, 300 min), filter them through a cellulose acetate filter, and then mix them with 1 mL of MeOH for storage. Determine the sample concentration at the absorption peak of 483 nm using a UV-Vis spectrophotometer. All experiments were repeated three times and the average value was taken to reduce experimental error and ensure accuracy.

[0139] The removal rates (%) of AO7 by different systems are shown in Table 2 and Figure 4 As shown:

[0140] Table 2

[0141]

[0142] As shown in Table 2 and Figure 4 As shown, the ability of PMS or modified electrolytic manganese slag systems to degrade AO7 is very low, but the ability of modified electrolytic manganese slag / PMS system to degrade AO7 is greatly improved. This means that the modified electrolytic manganese slag catalyst prepared by this invention can efficiently activate PMS and greatly improve the ability to degrade AO7.

[0143] Application Example 3

[0144] Prepare several portions of AO7 solution with an AO7 concentration of 40 mg / L. Add the modified electrolytic manganese slag catalyst from Example 3 to the AO7 solution and place them on a magnetic stirrer. The concentration of the modified electrolytic manganese slag catalyst is 0.3 g / L. React for 30 min to reach adsorption and desorption equilibrium. Add PMS at ambient temperature with a concentration of 1 mmol / L. Add chloride, nitrate, sulfate, and bicarbonate ions to the solution, each with a concentration of 20 mg / L. Also prepare a blank sample without added anions.

[0145] Take 3 mL samples at different time intervals (0, 5, 10, 15, 20, 300 min), filter them through a cellulose acetate filter, and then mix them with 1 mL of MeOH for storage. Determine the sample concentration at the absorption peak of 483 nm using a UV-Vis spectrophotometer. All experiments were repeated three times and the average value was taken to reduce experimental error and ensure accuracy.

[0146] The removal rates (%) of AO7 by the modified electrolytic manganese slag catalyst of Example 3 for different common anions are shown in Table 3. Figure 5 As shown:

[0147] Table 3

[0148]

[0149]

[0150] As shown in Table 3 and Figure 5 The image shows the effect of different common anions on the ability of modified electrolytic manganese slag to catalyze the degradation of AO7 by PMS. Among them, Cl... - The excessive Cl promotes the degradation of AO7, which may be due to the effect of excessive Cl. - It reacted with oxidizing active substances, generating HOCl or Cl in the system, thereby increasing the degradation rate of AO7; NO3 - It has almost no effect on the degradation of AO7; SO4 2- It had a certain inhibitory effect on the degradation of AO7, but the average degradation efficiency could still reach 99.3%. This may be because the high initial sulfate ion concentration inhibited the decomposition of PMS into sulfate ions, thus reducing the production of oxidatively active substances and thereby reducing the decomposition rate of AO7 to some extent; HCO3 - It has a certain inhibitory effect on the degradation of AO7, HCO3 - It may competitively adsorb onto the surface of modified electrolytic manganese slag compared to AO7. This competitive adsorption reduces the contact opportunities between AO7 and manganese slag, thereby decreasing the degradation efficiency of AO7 by PMS. However, the modified electrolytic manganese slag catalyst prepared in this invention still exhibits good performance and is capable of practical application.

[0151] Application Example 4

[0152] Several AO7 solutions were prepared, with an AO7 concentration of 40 mg / L. The modified electrolytic manganese slag catalyst from Example 3 was added to the AO7 solution and placed on a magnetic stirrer. The concentration of the modified electrolytic manganese slag catalyst was 0.3 g / L. The reaction was allowed to proceed for 30 min to reach adsorption and desorption equilibrium. PMS (1 mmol / L) was added at ambient temperature. Humic acid was added to the solution at concentrations of 5, 10, and 20 mg / L, respectively. No humic acid was added to the blank sample.

[0153] Take 3 mL samples at different time intervals (0, 5, 10, 15, 20, 300 min), filter them through a cellulose acetate filter, and then mix them with 1 mL of MeOH for storage. Determine the sample concentration at the absorption peak of 483 nm using a UV-Vis spectrophotometer. All experiments were repeated three times and the average value was taken to reduce experimental error and ensure accuracy.

[0154] The removal rate (%) of AO7 by the modified electrolytic manganese slag catalyst of Example 3 using humic acid is shown in Table 4. Figure 6 As shown:

[0155] Table 4

[0156]

[0157] As shown in Table 4 and Figure 6 The figure shows the effect of different concentrations of humic acid on the ability of modified electrolytic manganese slag to catalyze the degradation of AO7 by PMS. Under conditions of humic acid concentrations of 5.0 mg / L, 10.0 mg / L, and 20.0 mg / L, the degradation efficiencies of AO7 were 88.62%, 85.01%, and 84.75%, respectively. Compared to the condition without HA, the degradation efficiency of AO7 decreased by 7.3%, which may be because the humic acid reacted with the oxidizing active substances in the reaction system, thereby inhibiting the degradation efficiency of AO7. However, it can be found that even at a humic acid concentration of 20.0 mg / L, the degradation efficiency of AO7 was still as high as 84.8%. Therefore, humic acid has a certain impact on the ability of modified electrolytic manganese slag to catalyze the degradation of AO7 by PMS, but this modified electrolytic manganese slag catalyst still has the potential for application in complex water bodies.

[0158] Application Example 5

[0159] Prepare several portions of AO7 solution with an AO7 concentration of 40.0 mg / L. Add the modified electrolytic manganese slag catalyst from Example 3 to the AO7 solution and place them on a magnetic stirrer. The concentration of the modified electrolytic manganese slag catalyst is 0.3 g / L. React for 30 min to reach adsorption and desorption equilibrium. Add PMS at ambient temperature with a concentration of 1 mmol / L to adjust the pH of the solution to 4, 5, 6, 7, 8, 9, and 10. The pH of the blank sample is not adjusted.

[0160] Take 3 mL samples at different time intervals (0, 5, 10, 15, 20, 300 min), filter them through a cellulose acetate filter, and then mix them with 1 mL of MeOH for storage. Determine the sample concentration at the absorption peak of 483 nm using a UV-Vis spectrophotometer. All experiments were repeated three times and the average value was taken to reduce experimental error and ensure accuracy.

[0161] The effects of different pH values ​​on the removal rate (%) of AO7 by the modified electrolytic manganese slag catalyst in Example 3 are shown in Table 5. Figure 7 As shown:

[0162] Table 5

[0163]

[0164] As shown in Table 5 and Figure 7 The figure shows the effect of different pH values ​​on the catalytic degradation of AO7 by modified electrolytic manganese slag using PMS. It can be seen that pH has little effect on the modified electrolytic manganese slag catalyst prepared in this invention, and this modified electrolytic manganese slag catalyst still has the potential for application in complex water bodies.

[0165] Application Example 6

[0166] Several solutions were prepared, including AO7 solution, methyl orange solution, rhodamine B solution, tetracycline hydrochloride solution, and oxytetracycline hydrochloride solution, respectively. The concentration of AO7 solution was 40 mg / L, and the concentration of other pollutant solutions was 20 mg / L. The modified electrolytic manganese slag catalyst of Example 3 was added to the above solutions and placed on a magnetic stirrer. The concentration of the modified electrolytic manganese slag catalyst was 0.3 g / L. The reaction was carried out for 30 min to reach adsorption and desorption equilibrium. Potassium persulfate (PMS) was added at ambient temperature. The concentration of PMS was 1 mmol / L.

[0167] Take 3 mL samples at different time intervals (0, 5, 10, 15, 20, 300 min), filter them through a cellulose acetate filter, and then mix them with 1 mL of MeOH for storage. Determine the sample concentration at the absorption peak of 483 nm using a UV-Vis spectrophotometer. All experiments were repeated three times and the average value was taken to reduce experimental error and ensure accuracy.

[0168] The removal rates (%) of other pollutants by the modified electrolytic manganese slag catalyst in Example 3 are shown in Table 6 and Figure 8 As shown:

[0169] Table 6

[0170]

[0171] As shown in Table 6 and Figure 8 The figure shows the ability of modified electrolytic manganese slag to catalyze the degradation of other pollutants by PMS. It can be seen that the modified electrolytic manganese slag catalyst prepared in this invention still has a high removal efficiency for other organic pollutants, and this modified electrolytic manganese slag catalyst still has high application prospects.

[0172] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0173] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst for activating persulfate with modified manganese slag, characterized in that, Includes the following steps: Step 1: First, put the retrieved electrolytic manganese slag sample into an oven to dry it, then grind it with an agate mortar and pestle, and grind it into uniform powder with a high-speed pulverizer. Then, pass it through a 100-mesh sieve to prepare the original electrolytic manganese slag powder. Step 2: Mix the raw electrolytic manganese slag powder obtained in the previous step with deionized water and stir it on a magnetic stirrer to obtain a uniformly mixed electrolytic manganese slag suspension. The solid-liquid ratio of the original electrolytic manganese slag powder mixed with deionized water is 0.1 to 0.5 in kg:L; the stirring time of the electrolytic manganese slag suspension is 0.25 to 12 h; Step 3: Add calcium oxide to the above-mentioned uniformly mixed electrolytic manganese slag suspension, and continue to stir the mixture with a magnetic stirrer to obtain a fully reacted mixture. The addition ratio of calcium oxide to raw electrolytic manganese slag powder is 0.4–0.6 kg:kg; the stirring reaction time is 0.25–12 h. Step 4: Filter the mixture obtained above and rinse it with deionized water until the solution is neutral. Place the obtained solid in a drying oven and dry it at 75°C. Step 5: Grind the dried solid with an agate mortar and pass it through a 100-mesh sieve to prepare the modified electrolytic manganese slag catalyst.

2. The method for preparing the catalyst for activating persulfate with modified manganese slag according to claim 1, characterized in that: In step one, the electrolytic manganese slag sample is dried in an oven at 60-85°C for 24-72 hours to remove the remaining moisture in the electrolytic manganese slag, and then ground into small pieces with an agate mortar.

3. A modified electrolytic manganese slag catalyst prepared by the preparation method according to any one of claims 1-2.

4. The application of the modified electrolytic manganese slag catalyst as described in claim 3 in a persulfate activation system for the degradation of organic dyes or antibiotic wastewater in water bodies.

5. The application of the modified electrolytic manganese slag catalyst according to claim 4 in a persulfate activation system, characterized in that, Specifically, persulfate is added to water containing acid orange azo dyes to obtain a mixed solution. Then, a modified electrolytic manganese slag catalyst is added, and the mixture is stirred with a magnetic stirrer for 2-3 hours to complete the degradation of azo dyes in the water.

6. The application of the modified electrolytic manganese slag catalyst according to claim 5 in a persulfate activation system, characterized in that, In the water containing acid orange azo dye, the amount of persulfate added is 0.5–2 mmol / L; the amount of modified electrolytic manganese slag catalyst added is 0.25–2.00 g / L.

7. The application of the modified electrolytic manganese slag catalyst according to claim 6 in a persulfate activation system, characterized in that, The concentration of Acid Orange in the water body containing the Acid Orange azo dye is 10–100 mg / L.

8. The application of the modified electrolytic manganese slag catalyst according to claim 4 in a persulfate activation system, characterized in that: The pH range of the organic dye or antibiotic wastewater is 3 to 11; during the degradation reaction, the temperature of the degradation reaction is 5 to 40°C, and the time of the degradation reaction is 5 to 30 min.

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