A supported Ru-γ-MnO2 catalyst, its preparation method and application

Abstract

The present application relates to the field of advanced oxidation wastewater treatment technology, and particularly relates to a supported Ru-gamma-MnO2 catalyst and a preparation method and application thereof. The present application uses foamed nickel as a substrate, and through a thermoplastic polyurethane binder, an active component of Ru-doped gamma-MnO2 is loaded on the surface of the substrate to construct a supported composite catalyst with high catalytic activity and stability. In the process of activating peroxymonosulfate (PMS) to degrade organic pollutants in dyeing and printing wastewater, the catalyst exhibits excellent catalytic activity and stability. The catalyst preparation process is simple, and the cost is low. The effluent quality after treatment can meet the reuse requirements of textile dyeing process, and there is no significant difference in key indicators such as color difference and K / S value compared with industrial water, so the catalyst has a broad industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of advanced oxidation wastewater treatment technology, specifically to a supported Ru-γ-MnO2 catalyst, its preparation method, and its application. Background Technology

[0002] Wastewater discharged from the textile printing and dyeing industry has a complex composition, containing a large amount of recalcitrant organic dyes with high color intensity and toxicity, posing a serious threat to the aquatic environment. Advanced oxidation processes are an effective technology for degrading these organic pollutants. Among them, persulfate (PMS)-based advanced oxidation technology has attracted widespread attention due to the advantages of the sulfate radicals generated, such as strong oxidizing power, long half-life, and wide pH adaptability. The key to PMS activation is the development of efficient and stable catalysts.

[0003] Manganese oxides, due to their high environmental abundance and variable valence state, exhibit significant capabilities in the efficient activation of persulfate and the degradation of pollutants. The activation process of PMS primarily occurs on the catalyst surface, where its surface structure, electronic state, and defect properties have a decisive influence on the generation pathway of active species and reaction efficiency. However, how to precisely control the surface properties of manganese oxides to achieve efficient generation and utilization of active species, thereby improving their catalytic performance in practical water treatment systems, remains a significant challenge.

[0004] Therefore, developing a supported catalyst with high catalytic activity, excellent stability, and good practicality, as well as its preparation method, is of great significance for promoting the application of PMS advanced oxidation technology in actual wastewater treatment. Summary of the Invention

[0005] This invention provides a supported Ru-γ-MnO2 catalyst, its preparation method, and its applications. Using nickel foam as a substrate, Ru-doped γ-MnO2 active components are loaded onto the substrate surface via a thermoplastic polyurethane binder, constructing a supported composite catalyst with high catalytic activity and stability. This catalyst exhibits excellent catalytic activity and stability during the degradation of organic pollutants in textile dyeing wastewater by activated persulfate (PMS). The catalyst preparation process is simple and inexpensive. The effluent quality after treatment meets the reuse requirements of textile dyeing processes, showing no significant difference from industrial water in key indicators such as color difference and K / S value, demonstrating broad industrial application prospects.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a supported Ru-γ-MnO2 catalyst, comprising: S1. Dissolve divalent manganese salt and persulfate in deionized water, react hydrothermally, separate, wash, dry, and calcine to obtain γ-MnO2 powder; S2. The ruthenium source and the γ-MnO2 powder obtained in S1 are mixed and stirred in an environment with a pH of 1.0~3.0. After washing and drying, Ru-γ-MnO2 powder is obtained; the molar ratio of Ru in the ruthenium source to Mn in the γ-MnO2 is 1:(16~18). S3. The nickel foam substrate is subjected to acid washing, alcohol washing and water washing, and then dried to obtain pretreated nickel foam; S4. First, disperse the Ru-γ-MnO2 powder obtained in S2 in a polyurethane solution to obtain a Ru-γ-MnO2 / TPU mixed dispersion; then, impregnate the nickel foam obtained in S3 in the Ru-γ-MnO2 / TPU mixed solution, remove it, centrifuge and dry it to obtain a supported Ru-γ-MnO2 catalyst.

[0007] In this invention, the Ru doped by the impregnation method exists primarily in a surface-enriched form, rather than being uniformly dispersed within the catalyst. During catalysis, the adsorption and activation processes of PMS typically occur on the catalyst surface. Therefore, the Ru highly enriched on the γ-MnO2 surface can enhance the Mn-O orbital hybridization strength, weaken the Mn-O bond covalentity, and improve the Mn-E ratio. g The degree of orbital electron occupancy enhances the adsorption and activation of PMS molecules on the γ-MnO2 surface, thereby strengthening the generation of γ-MnO2-activated PMS. SO4 - The ability.

[0008] This invention utilizes nickel foam (NF) as a three-dimensional conductive substrate and employs thermoplastic polyurethane (TPU) to firmly encapsulate Ru-doped γ-MnO2 onto its surface, constructing a self-supporting manganese-based / NF ​​composite catalyst. On one hand, TPU, with its excellent film-forming properties and strong interfacial adhesion, effectively inhibits the shedding and loss of active components during the catalytic reaction. On the other hand, the three-dimensional porous nickel foam not only provides excellent mechanical support but also constructs efficient electron transport channels, significantly improving the conductivity and stability of the overall catalytic system. The synergistic effect of TPU and nickel foam in this invention significantly enhances the activation efficiency of persulfate (PMS) and promotes the generation of numerous reactive oxygen species, thereby achieving deep oxidation and efficient removal of organic pollutants from dyeing and printing wastewater.

[0009] Preferably, in S1, the divalent manganese salt is at least one of manganese sulfate, manganese nitrate, or manganese carbonate.

[0010] And / or, the persulfate is at least one of ammonium persulfate, potassium persulfate, or sodium persulfate.

[0011] And / or, the molar ratio of manganese in the divalent manganese salt to persulfate is (0.8~1.2):(0.8~1.2).

[0012] Preferably, in S1, the temperature of the hydrothermal reaction is 80~100℃.

[0013] And / or, the hydrothermal reaction time is 22 to 26 hours.

[0014] And / or, the calcination temperature is 250~350℃.

[0015] And / or, the calcination time is 1 to 3 hours.

[0016] Preferably, in S2, the ruthenium source is ruthenium trichloride.

[0017] Preferably, the concentration of the ruthenium source is 1.5~2.5 mmol / L.

[0018] Preferably, in step S2, the stirring time is 3 to 5 hours.

[0019] And / or, the drying temperature is 70~90℃.

[0020] And / or, the drying time is 22 to 26 hours.

[0021] Preferably, in step S4, the polyurethane solution is a mixed solution of thermoplastic polyurethane and N,N-dimethylformamide; the concentration of Ru-γ-MnO2 powder in the Ru-γ-MnO2 / TPU mixed dispersion is 3~7 g / L.

[0022] Preferably, the concentration of the thermoplastic polyurethane is 0.3~0.7 g / L.

[0023] Preferably, in step S4, the drying temperature is 90~110°C.

[0024] And / or, the drying time is 0.5 to 1.5 hours.

[0025] The present invention also provides a supported Ru-γ-MnO2 catalyst prepared by the above preparation method.

[0026] This invention also provides the application of a supported Ru-γ-MnO2 catalyst in activating persulfate for deep treatment of dyeing and printing wastewater and realizing its dyeing reuse.

[0027] Preferably, the application is as follows: the dyeing and printing wastewater is subjected to persulfate activation oxidation treatment under the action of the supported Ru-γ-MnO2 catalyst, and the treated effluent can be directly reused in the process of dyeing knitted cotton with reactive dyes.

[0028] Therefore, the present invention has the following beneficial effects: 1. This invention optimizes the electronic structure of γ-MnO2 by introducing Ru, effectively enhancing the electron density of Mn sites and weakening the covalent nature of the Mn-O bond, thereby significantly improving the electron density of Mn. g Orbital electron occupancy. This electronic structure modulation enhances the activation pathway of the catalyst for permonosulfate (PMS), promoting... SO4 - The efficient generation of [something] was simultaneously suppressed. 1 The generation of O2 enables the catalyst to achieve deep oxidation and efficient removal of organic pollutants in dyeing and printing wastewater.

[0029] 2. This invention uses thermoplastic polyurethane (TPU) as a bonding medium to stably support Ru-γ-MnO2 powder catalyst on a three-dimensional nickel foam framework. The strong adhesion and film-forming properties of TPU effectively prevent the active components from detaching and leaking during the reaction process. Simultaneously, the three-dimensional conductive nickel foam substrate provides stable mechanical support and an efficient electronic conduction network for the catalytic reaction. The synergistic effect of TPU and nickel foam enables the supported Ru-γ-MnO2 catalyst to exhibit excellent catalytic activity and stability during the activation of persulfate (PMS) to degrade organic pollutants in dyeing and printing wastewater.

[0030] 3. The residual concentration of organic pollutants in the dyeing wastewater treated by the supported Ru-γ-MnO2 / PMS system prepared by this invention is significantly reduced. This effluent can be directly reused for dyeing knitted cotton, and the color index of the fabric is not significantly different from that of fabric dyed with industrial water, fully meeting the requirements of the dyeing process for recycled water quality.

[0031] 4. The preparation method of the present invention is simple, mild, requires little equipment, and uses readily available raw materials, thus having good potential for process scale-up and large-scale production. Attached Figure Description

[0032] Figure 1 The images show the Tafel spectra of the supported catalysts prepared in Example 1 and Comparative Examples 1-3.

[0033] Figure 2 The PXRD spectra of the Ru-γ-MnO2-X catalysts prepared in Example 1 and Comparative Examples 4-7 are shown.

[0034] Figure 3 The N2 adsorption / desorption curves (a) and pore size distribution diagrams (b) of the Ru-γ-MnO2-X catalysts prepared in Example 1 and Comparative Examples 4-7 are shown.

[0035] Figure 4SEM images of the Ru-γ-MnO2-X catalysts prepared in Example 1 and Comparative Examples 4-7: Ru-γ-MnO2-0 (a), Ru-γ-MnO2-1 (b), Ru-γ-MnO2-2 (c), Ru-γ-MnO2-5 (d), Ru-γ-MnO2-10 (e); and the corresponding mapping image of Ru-γ-MnO2 (f).

[0036] Figure 5 High-resolution HAADF-STEM images (a, b) and elemental intensity distribution map (c) of the Ru-γ-MnO2 catalyst prepared in Example 1; magnified HAADF-STEM image of Ru-γ-MnO2 (d); EDS-STEM elemental mapping image of Ru-γ-MnO2 (e).

[0037] Figure 6 The Ru / Mn atomic ratio in the Ru-γ-MnO2-X catalysts prepared in Examples 1 and Comparative Examples 4-7 is shown in (a); the XPS full spectrum of the Ru-γ-MnO2-X catalysts prepared in Examples 1 and Comparative Examples 4 is shown in (b).

[0038] Figure 7 FTIR spectra of the Ru-γ-MnO2-X catalysts prepared in Example 1 and Comparative Examples 4-7 (a); wavenumbers in the range of 410-1500 cm⁻¹ -1 Enlarged view of the range (b); Raman spectrum of Ru-MnO2-X catalyst (c).

[0039] Figure 8 XPS spectra of the Ru-γ-MnO2 catalysts prepared in Example 1 and Comparative Examples 4-7: Mn 2p(a); Mn 3s(b); O 1s(c).

[0040] Figure 9 FE-SEM images of the supported catalysts prepared in Example 1 and Comparative Examples 8-12: NFT (a); RγMNF-0.2T (b); RγMNFT (c); RγMNF-1T (d); RγMNF-2T (e); RγMNF-10T (f).

[0041] Figure 10 The degradation of p-chlorophenol in the PMS system activated by the supported catalysts prepared in Examples 1 and Comparative Examples 1-13 (a) and its pseudo-first-order rate constant k (b).

[0042] Figure 11 It is a self-assembling continuous flow reactor.

[0043] Figure 12The degradation rate of p-chlorophenol by the RγMNFT-activated PMS prepared in Example 1 during continuous operation is shown.

[0044] Figure 13 Comparative photographs (a) and their corresponding EEM spectra of the RγMNFT-activated PMS system prepared in Example 1 before and after treatment of dyeing and printing wastewater: before treatment (b); after treatment (c).

[0045] Figure 14 This is a schematic diagram of the dyeing process.

[0046] Figure 15 The ultraviolet-visible absorption spectra of red (a), yellow (b), and blue (c) reactive dyes at a concentration of 0.1% prepared from recycled water treated in Example 1 and tap water are shown.

[0047] Figure 16 These are photographs of fabric samples dyed with recycled water and tap water after treatment in Example 1. Detailed Implementation

[0048] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0049]

Example

[0050] (2) Preparation of Ru-γ-MnO2: Prepare 50 mL of 2 mM RuCl3·3H2O aqueous solution, adjust the pH to 2 with hydrochloric acid, stir evenly, add 0.15 g of γ-MnO2 powder and continue stirring for 4 h. Then wash the solid powder with deionized water to remove residual raw materials and impurities. Finally, dry the washed solid powder in a vacuum oven at 80 °C overnight to obtain the Ru-γ-MnO2 catalyst, denoted as Ru-γ-MnO2-2.

[0051] (3) Pretreatment of nickel foam: Cut NF into substrates with dimensions of 100×200×1.5mm. First, sonicate in hydrochloric acid solution with pH=2 for 5min to remove the oxide layer formed by natural oxidation on the surface; then sonicate in anhydrous ethanol solution for 5min to remove adsorbed organic pollutants on the surface; then sonicate in deionized water for 5min to ensure the cleanliness of the NF substrate surface. After cleaning, place the NF in an 80℃ vacuum oven to dry overnight.

[0052] (4) Preparation of supported Ru-γ-MnO2 catalyst: First, 25 mg of thermoplastic polyurethane masterbatch was weighed and dissolved in 50 mL of DMF solvent to prepare a 0.5 g / L TPU solution. The Ru-γ-MnO2-2 powder catalyst (5 g / L) was uniformly dispersed in the TPU solution by ultrasonic dispersion to obtain a Ru-γ-MnO2 / TPU mixed solution. Then, the pretreated NF was immersed in the above mixed solution, stirred for 10 min, taken out, and slightly centrifuged to remove the dispersion on the surface of NF. It was then placed in a 100℃ oven and dried for 1 h to obtain the supported Ru-γ-MnO2 catalyst, denoted as RγMNFT.

[0053] Comparative Example 1 (1) Preparation of α-MnO2: 0.53 g MnSO4·H2O and 1.25 g KMnO4 powder were dissolved in 80 mL of deionized water and stirred at room temperature for 30 min to obtain a clear and transparent precursor solution. The solution was then transferred to a polytetrafluoroethylene reactor and reacted in an oven at 160 °C for 12 h. After cooling, the solid was filtered and dried, calcined in a muffle furnace at 300 °C for 2 h, and cooled to room temperature to obtain a black powder catalyst, denoted as α-MnO2.

[0054] (2) Preparation of Ru-α-MnO2: Prepare 50 mL of 2 mM RuCl3·3H2O aqueous solution, adjust the pH to 2 with hydrochloric acid, stir evenly, add 0.15 g of α-MnO2 powder and continue stirring for 4 h. Then wash the solid powder with deionized water to remove residual raw materials and impurities. Finally, dry the washed solid powder in a vacuum oven at 80 °C overnight to obtain the Ru-α-MnO2 catalyst, denoted as Ru-α-MnO2.

[0055] (3) Pretreatment of nickel foam: Cut NF into substrates with dimensions of 100×200×1.5mm. First, sonicate in hydrochloric acid solution with pH=2 for 5min to remove the oxide layer formed by natural oxidation on the surface; then sonicate in anhydrous ethanol solution for 5min to remove adsorbed organic pollutants on the surface; then sonicate in deionized water for 5min to ensure the cleanliness of the NF substrate surface. After cleaning, place the NF in an 80℃ vacuum oven to dry overnight.

[0056] (4) Preparation of supported Ru-α-MnO2 catalyst: First, 25 mg of thermoplastic polyurethane masterbatch was weighed and dissolved in 50 mL of DMF solvent to prepare a 0.5 g / L TPU solution. The Ru-α-MnO2 powder catalyst (5 g / L) was uniformly dispersed in the TPU solution by ultrasonic dispersion to obtain a Ru-α-MnO2 / TPU mixed solution. Then, the pretreated NF was impregnated in the above mixed solution, stirred for 10 min, taken out, and slightly centrifuged to remove the dispersion on the surface of NF. It was then placed in a 100℃ oven and dried for 1 h to obtain the supported Ru-α-MnO2 catalyst, denoted as RαMNFT.

[0057] Comparative Example 2 (1) Preparation of β-MnO2 powder: 1.69 g of MnSO4·H2O and 2.28 g of (NH4)2S2O8 powder were dissolved in 80 mL of deionized water and stirred at room temperature for 30 min to obtain a clear and transparent precursor solution. The solution was then transferred to a polytetrafluoroethylene reactor and reacted in an oven at 140 °C for 12 h. After cooling, the solid was filtered and dried, calcined in a muffle furnace at 300 °C for 2 h, and cooled to room temperature to obtain a black powder catalyst, denoted as β-MnO2.

[0058] (2) Preparation of Ru-β-MnO2: Prepare 50 mL of 2 mM RuCl3·3H2O aqueous solution, adjust the pH to 2 with hydrochloric acid, stir evenly, add 0.15 g of β-MnO2 powder and continue stirring for 4 h. Then wash the solid powder with deionized water to remove residual raw materials and impurities. Finally, dry the washed solid powder in a vacuum oven at 80 °C overnight to obtain the Ru-β-MnO2 catalyst, denoted as Ru-β-MnO2.

[0059] (3) Pretreatment of nickel foam: Cut NF into substrates with dimensions of 100×200×1.5mm. First, sonicate in hydrochloric acid solution with pH=2 for 5min to remove the oxide layer formed by natural oxidation on the surface; then sonicate in anhydrous ethanol solution for 5min to remove adsorbed organic pollutants on the surface; then sonicate in deionized water for 5min to ensure the cleanliness of the NF substrate surface. After cleaning, place the NF in an 80℃ vacuum oven to dry overnight.

[0060] (4) Preparation of supported Ru-β-MnO2 catalyst: First, 25 mg of thermoplastic polyurethane masterbatch was weighed and dissolved in 50 mL of DMF solvent to prepare a 0.5 g / L TPU solution. The Ru-β-MnO2 powder catalyst (5 g / L) was uniformly dispersed in the TPU solution by ultrasonic dispersion to obtain a Ru-β-MnO2 / TPU mixed solution. Subsequently, the pretreated NF was impregnated in the above mixed solution, stirred for 10 min, taken out, and slightly centrifuged to remove the dispersion on the surface of NF. Then, it was placed in a 100℃ oven and dried for 1 h to obtain the supported Ru-β-MnO2 catalyst, denoted as RβMNFT.

[0061] Comparative Example 3 (1) Preparation of δ-MnO2 powder: 0.28 g MnSO4·H2O and 1.50 g KMnO4 were dissolved in 80 mL of deionized water and stirred at room temperature for 30 min to obtain a clear and transparent precursor solution. The solution was then transferred to a polytetrafluoroethylene reactor and reacted in an oven at 80 °C for 48 h. After cooling, the solid was filtered and dried, calcined in a muffle furnace at 300 °C for 2 h, and cooled to room temperature to obtain a black powder catalyst, denoted as δ-MnO2.

[0062] (2) Preparation of Ru-δ-MnO2: Prepare 50 mL of 2 mM RuCl3·3H2O aqueous solution, adjust the pH to 2 with hydrochloric acid, stir evenly, add 0.15 g of δ-MnO2 powder and continue stirring for 4 h. Then wash the solid powder with deionized water to remove residual raw materials and impurities. Finally, dry the washed solid powder in a vacuum oven at 80 °C overnight to obtain the Ru-δ-MnO2 catalyst, denoted as Ru-δ-MnO2.

[0063] (3) Pretreatment of nickel foam: Cut NF into substrates with dimensions of 100×200×1.5mm. First, sonicate in hydrochloric acid solution with pH=2 for 5min to remove the oxide layer formed by natural oxidation on the surface; then sonicate in anhydrous ethanol solution for 5min to remove adsorbed organic pollutants on the surface; then sonicate in deionized water for 5min to ensure the cleanliness of the NF substrate surface. After cleaning, place the NF in an 80℃ vacuum oven to dry overnight.

[0064] (4) Preparation of supported Ru-δ-MnO2 catalyst: First, 25 mg of thermoplastic polyurethane masterbatch was weighed and dissolved in 50 mL of DMF solvent to prepare a 0.5 g / L TPU solution. The Ru-δ-MnO2 powder catalyst (5 g / L) was uniformly dispersed in the TPU solution by ultrasonic dispersion to obtain a Ru-δ-MnO2 / TPU mixed solution. Subsequently, the pretreated NF was impregnated in the above mixed solution, stirred for 10 min, taken out, and slightly centrifuged to remove the dispersion on the surface of NF. Then, it was placed in a 100℃ oven and dried for 1 h to obtain the supported Ru-δ-MnO2 catalyst, denoted as RδMNFT.

[0065] Comparative Example 4 This comparative example is basically the same as Example 1, except that: (2) the concentration of RuCl3·3H2O aqueous solution is adjusted to 0mM and the obtained catalyst is denoted as Ru-γ-MnO2-0; the supported γ-MnO2 catalyst obtained by treatment (3) and (4) is denoted as RγMNFT-0.

[0066] Comparative Example 5 This comparative example is basically the same as Example 1, except that: (2) the concentration of RuCl3·3H2O aqueous solution is adjusted to 1mM and the obtained catalyst is denoted as Ru-γ-MnO2-1; the supported Ru-γ-MnO2 catalyst obtained by treatment (3) and (4) is denoted as RγMNFT-1.

[0067] Comparative Example 6 This comparative example is basically the same as Example 1, except that: (2) the concentration of RuCl3·3H2O aqueous solution is adjusted to 5mM, and the obtained catalyst is denoted as Ru-γ-MnO2-5; the supported Ru-γ-MnO2 catalyst obtained by treatment (3) and (4) is denoted as RγMNFT-5.

[0068] Comparative Example 7 This comparative example is basically the same as Example 1, except that: (2) the concentration of RuCl3·3H2O aqueous solution is adjusted to 10mM and the obtained catalyst is denoted as Ru-γ-MnO2-10; the supported Ru-γ-MnO2 catalyst obtained by treatment (3) and (4) is denoted as RγMNFT-10.

[0069] Comparative Example 8 This comparative example is basically the same as Example 1, except that: (4) the TPU solution concentration is 0.2 g / L, and the obtained supported Ru-γ-MnO2 catalyst is denoted as RγMNF-0.2T.

[0070] Comparative Example 9 This comparative example is basically the same as Example 1, except that: (4) the TPU solution concentration is 1g / L, and the obtained supported Ru-γ-MnO2 catalyst is denoted as RγMNF-1T.

[0071] Comparative Example 10 This comparative example is basically the same as Example 1, except that: (4) the TPU solution concentration is 2g / L, and the obtained supported Ru-γ-MnO2 catalyst is denoted as RγMNF-2T.

[0072] Comparative Example 11 This comparative example is basically the same as Example 1, except that: (4) the TPU solution concentration is 10 g / L, and the obtained supported Ru-γ-MnO2 catalyst is denoted as RγMNF-10T.

[0073] Comparative Example 12 NF was cut into substrates measuring 100×200×1.5mm. First, it was sonicated in a hydrochloric acid solution (pH=2) for 5 minutes to remove the oxide layer formed by natural oxidation on the surface. Then, it was sonicated in anhydrous ethanol solution for 5 minutes to remove adsorbed organic contaminants. Finally, it was sonicated in deionized water for 5 minutes to ensure the cleanliness of the NF substrate surface. After cleaning, the NF was dried overnight in a vacuum oven at 80℃ to obtain pretreated nickel foam, denoted as NF.

[0074] Comparative Example 13 NF substrates were cut into 100×200×1.5mm pieces. First, they were sonicated in a hydrochloric acid solution (pH=2) for 5 minutes to remove the oxide layer formed by natural oxidation. Then, they were sonicated in anhydrous ethanol solution for 5 minutes to remove adsorbed organic contaminants. Finally, they were sonicated in deionized water for 5 minutes to ensure the cleanliness of the NF substrate surface. After cleaning, the NF substrates were dried overnight in an 80℃ vacuum oven to obtain pretreated nickel foam. The pretreated nickel foam was then immersed in a 0.5g / L TPU solution (25mg thermoplastic polyurethane masterbatch dissolved in 50mL DMF), stirred for 10 minutes, removed, and slightly centrifuged to remove the solution from the NF surface. It was then dried in a 100℃ oven for 1 hour to obtain TPU-coated nickel foam, denoted as NFT.

[0075] [Performance Testing] Tafel test: 5 mg of catalyst powder, 0.5 mL of ethanol, and 50 μL of perfluorosulfonic acid resin solution were mixed and dispersed evenly. Then, 5.0 μL of the dispersion was transferred using a pipette and coated onto the surface of a 5 mm glassy carbon electrode, which was then allowed to air dry to obtain the working motor. Test conditions were: a saturated calomel reference electrode; and 80 mL of 0.1 mol·L⁻¹ electrolyte. -1Na₂SO₄ solution, scan range -1 to 1 V, scan rate 0.01 V·s -1 .

[0076] Activated PMS degradation experiment: Prepare a 20 mg / L p-chlorophenol solution (or a 1:1 (mass ratio) mixture of 20 mg / L p-chlorophenol and 20 mg / L p-nitrophenol). Accurately weigh 10 mg of catalyst and add it to 50 mL of the contaminant solution, sonicating for 30 min to ensure uniform dispersion. Then, add 0.5 mM PMS to initiate the reaction. Every 2 min, transfer 1 mL of the reaction solution sample and immediately filter it through a 0.22 μm pore size aqueous microporous filter. Quickly add 30 μL of 0.1 mol·L⁻¹ PMS to the filtrate. -1 The residual PMS and ROS were quenched in Na2S2O3 solution to terminate the continued oxidation. As a control experiment, the PMS system alone was used without a catalyst, while other experimental conditions remained consistent. The degradation rate of organic pollutants (1-C) was measured. t / C0) is calculated using the following formula: 1-C t / C0=1-N t / N0 Where C t C0 is the concentration of p-chlorophenol (and p-nitrophenol) solution at time t, in mg / L; C0 is the initial concentration of p-chlorophenol (and p-nitrophenol) solution, in mg / L; N0 is the peak area of ​​the characteristic peak of p-chlorophenol (and p-nitrophenol) solution at time t; N0 t The peak area represents the initial characteristic peak of p-chlorophenol (and p-nitrophenol).

[0077] Under 10 hours of continuous operation, the removal performance of the catalyst for p-chlorophenol was assessed: p-chlorophenol was selected as the model pollutant. A self-assembled continuous fixed-bed flow-through reactor was constructed: RγMNFT catalyst was cut into several 20mm diameter discs and filled into the reactor pipes. During the experiment, PMS was added to a 10mg / L p-chlorophenol solution on the left side, and a peristaltic pump drove the flow from bottom to top through the catalyst bed reactor at a flow rate of 1rpm. The effluent after the reaction was collected from the upper outlet. To track the degradation of the pollutant during the reaction, samples were taken from the effluent at regular intervals, and the p-chlorophenol concentration was immediately determined by HPLC.

[0078] Performance Test of Recycled Dyeing Wastewater: 500 mL of dyeing wastewater was treated with 10 mM PMS activated by 0.2 g / L catalyst for 120 min. The resulting recycled water was directly used for dyeing with reactive dyes (Kyōnin Red K-3BE, Kyōnin Yellow K-3RE, and Kyōnin Blue K-BF), and compared with samples dyed with tap water. The knitted cotton fabric, reactive dyes, and auxiliaries used in the experiment were all provided by Zhejiang Daneng Dyeing Co., Ltd. based on the company's main processing categories. First, the cotton fabric was cut into 5×20 cm pieces, weighing approximately 2.25 g. The reactive dyes used were red, yellow, and blue primary colors, dyeing was performed at three dye concentration gradients (light, medium, and dark) with a liquor ratio controlled at 1:20. By comparing key indicators such as color difference and dye uptake with samples dyed with tap water, the applicability of recycled water in the dyeing process of complex dyeing wastewater was systematically evaluated. The specific dyeing process is as follows: (1) Staining prescription (Table 1) Table 1 Reactive dyeing formula for cotton

[0079] (2) Dyeing process flow like Figure 14 As shown.

[0080] (3) Soap washing prescription Soap flakes: 2g / L; Bath ratio: 1:20; Temperature: 98℃; Time: 10min.

[0081] Tafel analysis was performed on the supported catalysts prepared in Example 1 and Comparative Examples 1-3 to reveal the differences in their interfacial electron transfer capabilities. The results are as follows: Figure 1 As shown. By Figure 1 Observations show that the corrosion currents of RαMNFT, RβMNFT, RγMNFT, and RδMNFT are 1.56 × 10⁻⁶. -4 1.03×10 -4 1.75×10 -4 and 8.52×10 -6 A·cm -2 This phenomenon indicates that RγMNFT has the optimal electron transfer rate, thereby enhancing the activation ability of PMS.

[0082] PXRD tests were performed on the Ru-γ-MnO2-X catalysts prepared in Example 1 and Comparative Examples 4-7, and the results are as follows: Figure 2As shown, γ-MnO2 exhibits typical characteristic diffraction patterns at 2θ = 22.6°, 37.3°, 42.7°, and 56.4°, corresponding to the (120), (131), (300), and (160) crystal planes of γ-MnO2, respectively. After Ru doping, no characteristic peaks belonging to RuO2 were observed, indicating that Ru is uniformly dispersed in the γ-MnO2 lattice and no RuO2 crystal phase has formed. It is noted that the characteristic peak of the (160) crystal plane of γ-MnO2 shifts to the left after Ru doping. According to the Bragg equation (2dsinθ = nλ), the low-angle shift of the diffraction peak corresponds to the increase of the interplanar spacing d, indicating that the introduction of Ru leads to a slight distortion of the γ-MnO2 lattice. The larger radius Ru ions replace Mn, causing local lattice expansion. As the Ru doping amount increases, this offset first increases and then decreases. Among them, the interplanar spacing of Ru-γ-MnO2 is the largest. Excessive doping amount can easily lead to lattice strain saturation.

[0083] BET tests were performed on the Ru-γ-MnO2-X catalysts prepared in Example 1 and Comparative Examples 4-7, and the results are as follows: Figure 3 As shown in Table 2, all five catalyst samples exhibited typical type IV adsorption isotherms, accompanied by obvious H3-type hysteresis loops, indicating that they are all mesoporous structures. Table 2 shows that with increasing Ru content, the SBET of Ru-γ-MnO2-X (X = 1, 2, 5) increased from 54.09 m in the undoped form. 2 / g increased to 57.97, 60.57 and 97.67m respectively. 2 / g, while the average pore size decreased from 19.58 nm to 18.60, 17.22, and 18.34 nm, respectively. This is due to the moderate occupation of some mesopores by Ru species, which compresses the pore size but does not disrupt the overall mesoporous framework. Among them, Ru-γ-MnO2-5 has the highest specific surface area (97.67 nm). 2 / g) and the largest pore volume (0.45cm). 3 / g). However, when the doping concentration is 10mM, S BET Both the pore volume and the volume decreased significantly to 66.59m. 2 / g and 0.21cm 3 The average pore size decreased from 19.58 nm to 12.81 nm / g, possibly due to the collapse of the mesoporous structure caused by excessive Ru, resulting in pore blockage or merging. This optimization of the porous structure facilitates the exposure and mass transfer of γ-MnO2 active sites, promoting the adsorption and activation of PMS on the catalyst surface.

[0084] Table 2. Pore structure information of the Ru-γ-MnO2-X catalysts prepared in Example 1 and Comparative Examples 4-7.

[0085] The Ru-γ-MnO2-X catalysts prepared in Example 1 and Comparative Examples 4-7 were subjected to SEM-Mapping, STEM-EDS, and XPS tests, and the results are as follows: Figure 4-6 As shown in Table 3, γ-MnO2 exhibits a typical sea urchin-like structure with a diameter of approximately 6-10 μm, and the particle surface is uniformly covered with vertically grown nanorods. The catalyst retains its intact sea urchin-like structure after the introduction of Ru, indicating that Ru doping does not disrupt the bulk morphology of γ-MnO2. However, with increasing Ru doping concentration, the regularity of the nanorod arrangement on the γ-MnO2 surface gradually decreases. When the doping concentration is 10 mM, significant interweaving and connection occur between the nanorods, and the orderliness of the arrangement decreases. This indicates that Ru doping can modify the regularity of the nanorod arrangement through surface interactions, but does not affect the overall crystallinity and nucleation mode. Figure 4 As shown in (f), SEM-Mapping reveals that Mn (red), O (yellow), and Ru (green) are distributed in the Ru-γ-MnO2-2 catalyst structure. EDS quantitative analysis (Table 3) indicates that with increasing Ru doping concentration, the Ru / Mn atomic ratio in the catalyst gradually increases from 0 to 0.19, and shows a significant positive linear correlation with the Ru addition ratio. Figure 6 (a), R 2 =0.99), indicating that γ-MnO2 catalysts with different Ru doping amounts on the MnO2 surface were controllably prepared. To further investigate the distribution of Ru at the nanoscale, STEM-EDS elemental surface scanning analysis was performed (…). Figure 5 (e)). The results show that Ru (red) is highly dispersed at the nanoscale, and no obvious Ru clusters or nanoparticles were observed, which is consistent with the HAADF-STEM images ( Figure 5 (d) The single bright spot observed in the magnified image matches the pattern, preliminarily proving that Ru exists in an atomically dispersed form within the γ-MnO2 lattice. To verify the effect of Ru doping at the atomic scale, aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) was used to directly observe the atomic arrangement inside the sample. The results are as follows: Figure 5 As shown in (ab). The high-resolution image shows clear γ-MnO2 lattice fringes, and its magnified image ( Figure 5 (c) shows the ordered arrangement of atoms in the γ-MnO2 structure, where the brighter Ru directly substitutes for Mn and is embedded in the lattice. Furthermore, from Figure 6(b) XPS full-spectrum images revealed the presence of Mn and O elements in both undoped and Ru-doped γ-MnO2 catalysts. A distinct Ru 3p signal was observed at 463 eV in the Ru-γ-MnO2 full-spectrum, confirming the presence of Ru on the catalyst surface. With increasing Ru doping concentration, the Ru / Mn atomic ratio in the catalyst gradually increased from 0 to 0.35. Although both XPS and EDS detected an increase in the relative Ru content with increasing feed amount, the Ru / Mn ratio obtained by XPS (0-0.35) was significantly higher than that obtained by EDS (0-0.19). This difference is mainly due to the difference in detection depth between the two techniques: XPS has a detection depth of only about 10 nm, making it highly sensitive to surface elements; while EDS has a detection depth of up to 1 μm, averaging the elemental composition of the surface and bulk phases. Therefore, the high Ru content detected by XPS directly indicates that Ru doped by the impregnation method exists mainly in a surface-enriched form, rather than being uniformly dispersed within the catalyst, which is consistent with the HAADF-STEM observations. The adsorption and activation process of PMS usually occurs on the catalyst surface. Therefore, the Ru species enriched on the surface can directly affect the electronic coordination environment of the Mn sites on the surface, thereby affecting its activation efficiency of PMS.

[0086] Table 3. EDS and XPS information of Ru-γ-MnO2-X catalysts prepared in Example 1 and Comparative Examples 4-7

[0087] FTIR and Raman spectra were performed on the Ru-γ-MnO2-X catalysts prepared in Example 1 and Comparative Examples 4-7. The results are as follows: Figure 7 As shown in (ab), the FTIR spectrum of γ-MnO2 is located at ~518 cm⁻¹. -1 The peak exhibits typical Mn-O stretching vibration (corresponding to the vibration of Mn-O or Mn-O-Ru) at ~1379 cm⁻¹. -1 and ~950cm -1 The OH bending vibration peak was observed at 518 cm⁻¹. After Ru doping, the Mn-O stretching vibration in γ-MnO₂ increased from 518 cm⁻¹. -1 Shift to the low-frequency range to 513–517 cm -1 This indicates that the covalent strength of the Mn-O bond is weakened. This is because Ru atoms partially replace Mn atoms in the Mn-O bond, forming a new Mn-O-Ru asymmetric structure. This weakens the effect of the strongly electronegative oxygen atom on the decrease in electron density at the manganese sites, thereby increasing the electron density at the Mn sites. Raman spectroscopy ( Figure 7 (c) further validates this structural evolution. In the Raman spectrum of γ-MnO2, ~640 cm⁻¹ -1The high-frequency band corresponds to the stretching vibration of Mn-O. After Ru doping, this characteristic peak is significantly redshifted to ~632 cm⁻¹. -1 At lower wavenumbers, according to Hooke's law, the mechanical constant k of the Mn-O bond is positively correlated with the Raman shift. When the vibrational peak of the Mn-O bond shifts to lower wavenumbers, the Mn-O bond strength weakens. Therefore, Ru doping reduces the covalent strength of the Mn-O bond, which is beneficial for forming weak coordination adsorption with PMS and promotes the homolytic cleavage of the -OO- bond to generate free radicals.

[0088] XPS tests were performed on the Ru-γ-MnO2-X catalysts prepared in Example 1 and Comparative Examples 4-7, and the results are as follows: Figure 8 As shown in (a), the high-resolution Mn 2p spectrum shows that the characteristic peaks of undoped Ru-MnO2-0 at 653.85 eV and 641.95 eV are attributed to Mn 2p, respectively. 1 / 2 and Mn 2p 3 / 2 After Ru doping, Mn 2p 1 / 2 The binding energy shifts significantly towards lower binding energies, a phenomenon consistent with theoretical predictions that Ru doping induces a decrease in the valence state of Mn. This downward trend indicates that Ru doping promotes the reduction of Mn(Ⅳ) to Mn(Ⅲ). The distortion of Mn(Ⅲ) leads to an increase in the Mn-O bond length, weakening its covalentity and consequently reducing the binding force of the Mn nucleus on the 2p inner-shell electrons, ultimately manifesting as an overall low-energy shift of the Mn 2p peak. (Mn 3s spectrum) Figure 8 (b) Further verification of this electronic structure evolution. With increasing Ru doping concentration, the binding energy difference ΔE between the two peaks first increases and then decreases, with the largest ΔE (approximately 5.40 eV) observed in Ru-MnO2-2. According to the formula AOS = 8.956... The average oxidation state of Mn calculated using ΔE 1.126 shows that the AOS of Ru-MnO2-2 is 2.88, which is the lowest level, indicating that its Mn(III) proportion is the highest. This suggests that appropriate Ru doping is beneficial for the reduction of Mn(IV) to Mn(III), while excessive doping leads to a weakening of the reduction effect. Furthermore, the change in the chemical state of surface oxygen further confirms the regulatory role of Ru doping on the coordination environment. The high-resolution O 1s XPS spectrum of Ru-MnO2-X... Figure 8 In (c), two types of oxygen were identified through peak fitting, with binding energies corresponding to lattice oxygen (O) at 529.7 eV. latt ) and 531.0 eV of adsorbed oxygen (O ads After Ru doping, O ads / O latt The ratio increased from 0.59 to 3.61, significantly improving O ads The concentration indicates that Ru doping increases the oxygen vacancy concentration in γ-MnO2. In summary, Ru doping promotes the reduction of Mn(Ⅳ) to Mn(Ⅲ) and increases the oxygen vacancy concentration.ads This increases the concentration of oxygen vacancies, thereby enhancing the activation ability of γ-MnO2 for PMS.

[0089] The supported catalysts prepared in Example 1 and Comparative Examples 8-12 were subjected to FE-SEM testing, and the results are as follows: Figure 9 As shown. When the TPU concentration is 0.2 g / L, the number of Ru-γ-MnO2 particles loaded on the NF framework surface is relatively small, and the particle spacing is large. This is because the bonding force formed by low-concentration TPU is weak and cannot effectively fix the powder particles, resulting in some powder particles failing to adhere stably. As the TPU concentration increases to 0.5-2 g / L, the number of particles loaded on the framework surface gradually increases, and the particles are densely arranged, almost completely covering the NF surface. This indicates that appropriately increasing the TPU concentration helps to enhance the bonding between Ru-γ-MnO2 and the foamed nickel substrate, and improve the loading efficiency of Ru-γ-MnO2 powder. However, when the TPU concentration continues to increase to 10 g / L, the number of particles on the Ni framework surface decreases. This may be due to the reduction of Ru-γ-MnO2 component in the TPU and Ru-γ-MnO2 composite film material. In addition, we also speculate that excessively high TPU concentration causes Ru-γ-MnO2 to agglomerate, which is not conducive to its loading on the framework. Further high-magnification observation of the surface morphology of the supported Ru-γ-MnO2 catalyst ( Figure 9 (Inset in the upper right corner) It was found that when the TPU concentration was below 1 g / L, Ru-γ-MnO2 retained its original sea urchin-like structure; when the TPU concentration was 2 g / L, the particle surface was coated with a continuous TPU film, and the nanorods on the sea urchin-like surface were bound; when the concentration was further increased to 10 g / L, the Ru-γ-MnO2 surface was almost completely coated with a TPU film. This indicates that excessive TPU will cover the active sites of Ru-γ-MnO2, thereby reducing the catalyst's reactivity.

[0090] EDS tests were performed on the supported catalysts prepared in Example 1 and Comparative Examples 8-12. The results are shown in Table 4. As the TPU content increased to 2 g / L, the mass percentage of Ni in the catalyst gradually decreased from 99.20% to 29.13%, while the mass percentage of Mn gradually increased from 0 to 42.60%. This indicates that the loading of Ru-γ-MnO2 powder on the NF surface increased and the coverage area gradually increased, and the previously exposed Ni was blocked, confirming that increasing the TPU concentration is beneficial to improving the loading of Ru-γ-MnO2. However, when the TPU concentration reached 10 g / L, the Mn content decreased to 18.56% and the Ni content increased to 48.47%, indicating that the loading of Ru-γ-MnO2 on the NF substrate surface decreased, which is consistent with the phenomenon observed by FE-SEM.

[0091] Table 4. EDS information of the supported catalysts prepared in Example 1 and Comparative Examples 8-12

[0092] The supported catalysts prepared in Example 1 and Comparative Examples 1-13 were subjected to activated PMS degradation experiments for p-chlorophenol. Figure 10 As shown. By Figure 10 Observations show that the k values ​​of Comparative Examples 1-3 are significantly lower than those of Example 1, indicating that the crystal structure of γ-MnO2 is favorable for the catalytic reaction. Comparing the k values ​​of Example 1 and Comparative Examples 4-7, it can be found that as the Ru loading increases from 0 mM to 2 mM, the k value increases from 0.25 min... -1 Significantly improved to 0.66 and 0.85 min. -1 However, when the loading was further increased to 5 mM and 10 mM, the activity decreased instead of increasing to 0.80 and 0.002 min, respectively. -1 And lower than Example 1 (0.85 min) -1 This indicates that excessive Ru loading may lead to Ru species aggregation, clogging the carrier pores and consequently reducing the utilization rate of active sites. Comparative Examples 12-13 failed to effectively degrade p-chlorophenol, indicating that neither the NF matrix nor the TPU binder itself can activate PMS to degrade p-chlorophenol. After loading the active component Ru-γ-MnO2, p-chlorophenol was completely degraded in Examples 1 and 8-11 within 10 min, with the k value showing a trend of first increasing and then decreasing with increasing TPU concentration: when the TPU concentration increased from 0.2 g / L to 2 g / L, the corresponding k values ​​were 0.52, 0.85, 0.54, and 0.49 min, respectively. -1 Among the tested samples, Example 1 (TPU concentration of 0.5 g / L) exhibited the best catalytic activity, with k values ​​increasing by 63.46%, 57.41%, and 73.47% compared to Comparative Examples 8-10, respectively. This indicates that a suitable TPU concentration facilitates the stable loading and effective exposure of the Ru-γ-MnO2 active component on the NF surface, thereby improving the PMS activation and degradation efficiency. However, Comparative Example 11 completely lost its catalytic activity, indicating that excessive TPU caused the active sites to be completely covered, severely hindering the contact between PMS and the active sites, which is consistent with the results observed by FE-SEM. No detachment of the active component was observed during the experiment, confirming that the TPU binder ensured the stable coating of Ru-γ-MnO2 onto the NF substrate, improving the problem of easy detachment of the active component in traditional supported catalysts.

[0093] To further investigate the catalytic behavior of the catalyst in the complex pollution system, the synergistic degradation effects of the catalysts in Example 1 and Comparative Examples 4-11 on a mixed solution of p-chlorophenol and p-nitrophenol were tested. The results are shown in Table 5. During the co-degradation process, the two pollutants exhibited significant competitive adsorption behavior at the active sites of the catalyst and showed competitive consumption of reactive oxygen species. Both p-chlorophenol and p-nitrophenol molecules have electron-deficient benzene ring structures, but their reaction behaviors differ significantly: p-chlorophenol tends to undergo oxidation due to its electron-deficient characteristics, while p-nitrophenol is preferentially reduced due to its electron-deficient nature. This difference in reaction pathways leads to mutual inhibition between the two in the coexisting system, making it difficult for the catalyst to simultaneously and efficiently remove both pollutants under the same reaction conditions, as the catalyst usually preferentially degrades one of the pollutants. As shown in Table 5, Example 1 exhibited the best performance in this system, achieving almost complete degradation of p-chlorophenol within 10 minutes and simultaneously achieving an 85% removal rate of p-nitrophenol, demonstrating excellent broad-spectrum synergistic degradation ability. Compared with Example 1 and Comparative Examples 4-7, when the Ru loading increased from 0 mM to 2 mM (Example 1), the number of active sites increased, and the catalytic performance was significantly improved. However, excessively high loading (10 mM) easily led to agglomeration, resulting in decreased activity, reduced effective active area, limited reaction mass transfer, and a decrease in degradation efficiency. Compared with Example 1 and Comparative Examples 8-11, when the TPU concentration was 0.5 g / L (Example 1), both a firm catalyst loading on the nickel foam and sufficient exposure of active sites could be achieved simultaneously. However, when the concentration increased to 10 g / L (Comparative Example 11), the excessively thick TPU layer covered some active sites, hindering the contact between pollutant molecules and active centers, resulting in a significant decrease in degradation performance.

[0094] Table 5 Performance of the supported catalysts prepared in Example 1 and Comparative Examples 4-11 in activating PMS for simultaneous degradation of p-chlorophenol and p-nitrophenol

[0095] Employing self-assembled continuous flow reactors (e.g.) Figure 11 As shown in the figure, the removal performance of p-chlorophenol and water quality safety of Example 1 were investigated under 10h continuous operation conditions. The results are as follows. Figure 12As shown in the figure. Without the addition of PMS, after 2 hours of adsorption operation, the removal rate of p-chlorophenol in Example 1 remained stable at approximately 13%, indicating that the catalyst had reached adsorption saturation. Subsequently, 2 mM PMS was added to the p-chlorophenol solution to initiate a Fenton-like reaction. After 10 hours of continuous operation, the removal rate of p-chlorophenol in the RγMNFT / PMS system remained stable at 100%, fully verifying the excellent stability and anti-deactivation ability of the catalytic system during long-term operation. Further analysis of metal ion precipitation in the effluent after 10 hours of continuous operation yielded results shown in Table 6. The Mn ion precipitation concentration was only 0.06 mg / L, far below the ≤0.2 mg / L specified in the "Water Quality Standard for Reclaimed Water in Textile Dyeing and Finishing Industry" (FZ / T 01107-2011); the Ni ion precipitation concentration was 0.25 mg / L, lower than the ≤1.0 mg / L specified in the "Integrated Wastewater Discharge Standard" (GB8978-1996); and the Ru ion precipitation concentration was 0.04 mg / L, which is at a low level. The leaching concentrations of key metal ions all meet the corresponding water quality standards, indicating that the system has good environmental safety in practical applications. These results demonstrate that the RγMNFT / PMS system not only maintains excellent and stable catalytic performance during long-term operation, but also exhibits extremely low effluent metal ion precipitation, meeting the stringent requirements for wastewater discharge and reclaimed water quality in the textile dyeing and finishing industry. This provides crucial technical support and safety assurance for its practical application in the treatment of complex industrial wastewater.

[0096] Table 6. Concentration of metal ions precipitated in the effluent of the RγMNFT / PMS system

[0097] Dyeing and printing wastewater from Zhejiang Daneng Printing and Dyeing Co., Ltd. was collected. Table 7 summarizes the typical characteristics of the wastewater before and after treatment. EEM spectroscopy was used to analyze the organic matter composition and structure of the wastewater, and the effectiveness of RγMNFT-activated PMS treatment for the wastewater was evaluated. First, the color of the wastewater was observed (…). Figure 13 (a) The color changed from black before treatment to clear and transparent, with its chroma decreasing from 64 times to 0 times, far below the 25 times requirement for dyeing and printing wastewater reuse. This indicates that the RγMNFT / PMS system can effectively remove color from wastewater, providing a basis for dyeing in reused water. Figure 13(bc) indicates that the wastewater before treatment mainly contains aromatic proteins, soluble microbial byproducts, and humic acid-like organic matter. After treatment with RγMNFT, the fluorescence peaks in the four characteristic regions of the original EEM spectrum almost completely disappeared, indicating that the macromolecular organic pollutants (such as aromatic proteins and soluble microbial byproducts) in the system have been efficiently degraded and destroyed. After degradation, the TOC and COD of the dyeing and printing wastewater were only 16.63 and 39.23 mg / L, respectively, with removal rates of 58.90% and 73.62%, respectively, meeting the reuse standard requirements. This shows that the RγMNFT / PMS system can not only achieve deep destruction and transformation of complex organic components, but also shows excellent reuse potential.

[0098] Table 7 Typical water quality characteristics of dyeing and printing wastewater before and after treatment

[0099] Three typical monochlorotriazine monoazo reactive dyes—Kyōnin Red K-3BE, Kyōnin Yellow K-3RE, and Kyōnin Blue K-BF—were selected. Dye solutions with a mass fraction of 0.1% were prepared using tap water and recycled water treated with PMS as solvents, respectively. The dye solutions were incubated at 60℃ for 2 hours to simulate the actual dyeing process environment. Subsequently, the differences and stability of their absorbance curves were analyzed using a UV-Vis spectrophotometer. The results are as follows: Figure 15 As shown, the red, yellow, and blue dyes exhibit maximum absorption peaks at 542 nm, 418 nm, and 612 nm, respectively. Furthermore, the absorbance curves of the dye solutions prepared from the two types of water show consistent peak positions and heights, indicating that the recycled water after deep PMS treatment did not interact with the chromophores of the reactive dyes, and that high-temperature treatment did not cause the breakage of the conjugated system or destruction of the functional groups in the dye molecules. These results demonstrate that the recycled water is comparable to tap water in terms of chromophore performance and chemical stability, possessing good dye compatibility and process applicability.

[0100] The dyeing rates of three dyes on knitted cotton fabrics were calculated, and the dyeing differences between tap water and recycled water were analyzed. The results are shown in Table 8. Overall, the dyeing rate in recycled water was slightly lower than that in tap water, with a more significant difference at 0.1% concentrations of the three primary color dye solutions (4%-7.40%). However, when the dye concentration increased to 5%, the difference in dyeing rates between the two sources decreased significantly (≤0.2%). This may be because trace amounts of intermediates remaining in recycled water compete with the dye for adsorption sites, resulting in a reduction in the effective adsorption of light-colored dyes and a decrease in dyeing rate. In addition, at different concentrations, the dyeing rate difference of blue dye was smaller than that of red and yellow dyes, which is closely related to the reactivity (R value) of the dye. For monochlorotriazine reactive dyes, the R value determines their reaction rate with fibers: the smaller the R value, the weaker the nucleophilic substitution reaction activity between the dye and the fiber. Although the dyeing rate is slow, it is easier to reach adsorption-desorption equilibrium, resulting in a high equilibrium adsorption capacity. The R values ​​of the three primary colors used in the experiment—Kingren Red K-3BE, Kingren Yellow K-3RE, and Kingren Blue K-BF—were 64.70, 67.05, and 64.09, respectively. Among them, the blue dye had the lowest R value, indicating that its reactivity during the dyeing process was relatively weak, which was conducive to the adsorption and desorption of dye molecules on the fiber surface reaching an equilibrium. In contrast, the red and yellow dyes reacted faster during the dyeing process, which would disrupt this equilibrium and reduce the effective adsorption efficiency of the dyes on the fiber surface, thus resulting in significant fluctuations in the dyeing rate.

[0101] Table 8 Dyeing uptake rates of tap water and recycled water

[0102] Actual photos of cotton fabrics dyed using tap water and recycled water, as shown below. Figure 16As shown in the figure. Visual observation revealed no significant differences in color characteristics between the two groups of dyed samples. To further evaluate the suitability of recycled water for dyeing, a colorimeter was used to analyze the differences in color characteristic values ​​of light (0.1%), medium (2.0%), and dark (5.0%) cotton fabrics, including L, a, b, DE, and K / S values ​​in the CIE model, representing lightness, red-green value, yellow-blue value, color difference, and color depth, respectively, summarized in Table 9. The results showed that in the recycled water dyed samples, the color difference values ​​(DE) of the three concentrations of red dye, and the light concentrations of yellow and blue dyes, differed significantly, indicating a relatively obvious color difference; while the color difference between the medium and dark concentrations of yellow and blue dyes and the tap water dyed samples was less than 1, meeting the enterprise's production standards. A similar pattern was observed in the K / S value trend: the K / S value of red fabrics differed significantly between the two water qualities, while the difference was smaller for yellow and blue fabrics. From a molecular structure perspective, both red and yellow dyes are monoazo dyes, which have relatively weak molecular structure stability and a high content of electron-donating groups, making them more susceptible to degradation by residual oxides in recycled water. Blue dyes, on the other hand, are diazo dyes, with a more stable molecular skeleton, relatively fewer electron-donating groups, and stronger antioxidant capacity. Due to their higher concentration, even slight color differences in dark dyes are difficult to detect with the naked eye. Therefore, blue dyes exhibit smaller color deviations compared to red and yellow dyes, and the color of darker systems is less affected by water quality. These results indicate that when using dyeing wastewater treated with activated PMS in Example 1 for reactive dyeing of knitted cotton, dyes with fewer electron-donating groups and more stable structures are more suitable, and darker dyeing systems are also more appropriate.

[0103] Table 9. Color Characteristic Values ​​of Tap Water and Reclaimed Water

[0104] The selected dye is a monochlorotriazine type monoazo reactive dye, Jingren Blue K-BF (dye: 5% (owf)%); sodium sulfate: 70 g / L; soda ash: 20 g / L; leveling agent: 1 g / L; dyeing process as follows: Figure 14As shown in Table 10, the dyeing performance of recycled dyeing wastewater treated with different catalyst depths was evaluated based on the dyeing results of tap water. Table 10 shows that the recycled water treated in Example 1 had the closest dyeing rate (81.10%), color difference (CIE DE 0.28), and color depth (K / S 22.58) to the tap water standard (81.20%, K / S 23.79), indicating that its dyeing suitability is comparable to tap water. In contrast, most of the recycled water treated in the comparative examples showed significant disadvantages in at least one indicator: the color difference (CIE DE) of comparative examples 3, 4, 7, and 11 was significantly higher (1.93-3.68), indicating poor color consistency; the K / S values ​​of comparative examples 2, 3, 4, and 7 were lower (15.21-17.32), reflecting insufficient color depth; and the dyeing rate of comparative example 7 was only 50.35%, significantly lower than the other groups. In summary, the deep treatment in Example 1 can produce high-quality recycled water that meets the requirements of high-standard dyeing processes, providing a reliable technical solution with clear industrialization potential for solving the core problem of water resource recycling in the printing and dyeing industry.

[0105] Table 10 Comparison of dyeing performance between recycled water and tap water after treatment in Example 1 and Comparative Examples 1-11

Claims

1. A method for preparing a supported Ru-γ-MnO2 catalyst, characterized in that, include: S1. Dissolve divalent manganese salt and persulfate in deionized water, react hydrothermally, separate, wash, dry, and calcine to obtain γ-MnO2 powder; S2. The ruthenium source and the γ-MnO2 powder obtained in S1 are mixed and stirred in an environment with a pH of 1.0~3.

0. After washing and drying, Ru-γ-MnO2 powder is obtained; the molar ratio of Ru in the ruthenium source to Mn in the γ-MnO2 is 1:(16~18). S3. The nickel foam substrate is subjected to acid washing, alcohol washing and water washing, and then dried to obtain pretreated nickel foam; S4. First, disperse the Ru-γ-MnO2 powder obtained in S2 in a polyurethane solution to obtain a Ru-γ-MnO2 / TPU mixed dispersion; then, impregnate the nickel foam obtained in S3 in the Ru-γ-MnO2 / TPU mixed solution, remove it, centrifuge and dry it to obtain a supported Ru-γ-MnO2 catalyst.

2. The preparation method according to claim 1, characterized in that, In S1, the divalent manganese salt is at least one of manganese sulfate, manganese nitrate, or manganese carbonate; And / or, the persulfate is at least one of ammonium persulfate, potassium persulfate, or sodium persulfate; And / or, the molar ratio of manganese in the divalent manganese salt to persulfate is (0.8~1.2):(0.8~1.2).

3. The preparation method according to claim 1, characterized in that, In S1, the temperature of the hydrothermal reaction is 80~100℃; And / or, the hydrothermal reaction takes 22 to 26 hours; And / or, the calcination temperature is 250~350℃; And / or, the calcination time is 1 to 3 hours.

4. The preparation method according to claim 1, characterized in that, In S2, the ruthenium source is ruthenium trichloride; Preferably, the concentration of the ruthenium source is 1.5~2.5 mmol / L.

5. The preparation method according to claim 1, characterized in that, In S2, the stirring time is 3-5 hours; And / or, the drying temperature is 70~90℃; And / or, the drying time is 22 to 26 hours.

6. The preparation method according to claim 1, characterized in that, In S4, the polyurethane solution is a mixed solution of thermoplastic polyurethane and N,N-dimethylformamide; the concentration of Ru-γ-MnO2 powder in the Ru-γ-MnO2 / TPU mixed dispersion is 3~7 g / L; Preferably, the concentration of the thermoplastic polyurethane is 0.3~0.7 g / L.

7. The preparation method according to claim 1, characterized in that, In S4, the drying temperature is 90~110℃; And / or, the drying time is 0.5 to 1.5 hours.

8. The supported Ru-γ-MnO2 catalyst prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the supported Ru-γ-MnO2 catalyst as described in claim 8 in activating persulfate for deep treatment of dyeing and printing wastewater and realizing its dyeing reuse.

10. The application as described in claim 9, characterized in that, The application is as follows: dyeing and printing wastewater is subjected to persulfate activation oxidation treatment under the action of the supported Ru-γ-MnO2 catalyst, and the treated effluent can be directly reused in the process of dyeing knitted cotton with reactive dyes.

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