Novel method for oxidizing refractory organic matters by activating peracetic acid through mediating active hydrogen by using heterogeneous Fenton catalyst

Abstract

The invention relates to a novel method for oxidizing refractory organic matters by activating peracetic acid through mediating active hydrogen by a heterogeneous Fenton catalyst. The invention relates to a novel heterogeneous Fenton catalyst and application thereof, in particular to a nickel-copper modified sulfurized zero-valent iron heterogeneous Fenton catalyst (ZVI-S at Ni2Cu) and application thereof in catalyzing peroxyacetic acid to remove refractory organic matters in water. The heterogeneous Fenton catalyst can rapidly catalyze peracetic acid (PAA) by generating active hydrogen (H *), so that refractory organic pollutants in water are efficiently removed, the pH application range is wide, and generation of nitro toxic by-products and azo toxic by-products in the oxidation process of degrading amino-containing pollutants (such as sulfonamides) can be inhibited.

Description

Technical Field

[0001] This invention relates to a novel heterogeneous Fenton catalyst and its uses, specifically a nickel-copper modified zero-valent iron sulfide heterogeneous Fenton catalyst and its use in catalytically removing recalcitrant organic matter from water. Background Technology

[0002] Peracetic acid (PAA) has become an ideal alternative oxidant for Fenton-like reactions because its OO bond dissociation energy (159 kJ / mol) is lower than that of H₂O₂ (213 kJ / mol) and persulfate (317 kJ / mol), making it easier to activate and effectively removing recalcitrant organic pollutants from water. Furthermore, the organic free radicals (RC•) generated after PAA activation exhibit stronger oxidative selectivity than •OH and are less affected by water quality. Traditional homogeneous Fenton-like systems have stringent pH requirements (typically exhibiting high catalytic activity only within the pH range of 2.5–3.5) and suffer from drawbacks such as difficulty in catalyst separation and recovery, and secondary pollution caused by iron ion loss. Therefore, research is increasingly turning to heterogeneous Fenton reaction catalysts. Common heterogeneous catalysts used for PAA activation include carbon-based materials and transition metal-based materials. It is well known in the art that heterogeneous catalysts with transition metals as active sites exhibit significantly higher activity. However, these catalyst / PAA systems still have two problems: (1) Transition metals typically activate PAA via a single-electron transfer pathway, which has limited reducibility, making it difficult to meet the high-efficiency requirements of actual wastewater treatment in terms of pollutant degradation rates; (2) When heterogeneous catalyst / PAA systems degrade amino-containing pollutants (such as sulfonamides), free radicals easily attack nitrogen atoms, generating toxic azo or nitro byproducts, increasing environmental risks. Therefore, it is necessary to find activation pathways with lower reaction barriers while suppressing the generation of toxic byproducts.

[0003] Through numerous experiments, the inventors unexpectedly discovered that mediated active hydrogen (H*) can efficiently activate PAA over a wide pH range. Furthermore, H* is a nucleophile, effectively blocking the coupling and oxidation of N-centered organic free radicals, thus inhibiting the formation of toxic nitro and azo byproducts at the source. H*-mediated activation of oxides mainly occurs through electrochemical systems and heterogeneous catalytic systems requiring no additional energy input. The generation of H* at the cathode based on electrocatalytic technology has been extensively reported. For example, invention patents (CN110342615A) and (CN 117843086A) report the efficient generation of H* mediated by PdFe nanoalloy carbon aerogel cathodes and Pd / CuOx heterojunction cathodes, respectively, significantly improving the activation rate of oxidants. However, electrochemical systems require high energy consumption and complex electrocatalytic reactors. Without energy input, Chen, X. et al. [see Journal of Environmental Chemical Engineering 11 (2023) 109442] and Zhang, Y. [see Separation and Purification Technology 303 (2022) 122187] et al. reported on TiO2@MnO2 catalysts and SiC-Fe catalysts, respectively. 0 Catalysts mediate the activation of H2O2 and persulfate by H* to remove antibiotics, but the O2O bond dissociation energies of H2O2 and persulfate are higher than those of PAA. Both systems require high doses of catalyst and oxidant to rapidly remove recalcitrant organic matter, and the pollutant removal rates are not satisfactory. No studies have been reported on the targeted design of a catalyst to mediate H* activation for PAA. Therefore, there is still an urgent need for a heterogeneous catalyst with extremely high catalytic efficiency and a wide pH range to mediate H* activation of PAA. Summary of the Invention

[0004] Through numerous experiments, the inventors unexpectedly discovered that a heterogeneous catalyst based on nickel-copper metal modified with zero-valent iron sulfide (ZVI-S) can generate a large amount of H*, which is effectively used to activate PAA. This catalytic material, through modification and alteration of ZVI, can rapidly and efficiently remove recalcitrant organic matter (such as tetracycline (CT), sulfadiazine (SMZ), naproxen (NAP)) from water as a heterogeneous Fenton catalyst. It exhibits excellent PAA catalytic effect, a particularly wide pH range, and can simultaneously inhibit the formation of nitro-toxic and azo-toxic byproducts during the oxidation of amino-containing pollutants (such as sulfonamides). Furthermore, it can remove recalcitrant organic matter from the effluent of actual secondary sedimentation tanks.

[0005] The heterogeneous Fenton catalyst of the present invention is obtained by first obtaining ZVI-S by mechanical ball milling, and then loading nickel and copper elements on the surface of ZVI-S by hydrothermal method according to the Kirkendall effect, thereby obtaining the heterogeneous catalytic material based on ZVI surface modification of the present invention.

[0006] Therefore, the first objective of this invention is to provide a catalyst for activating PAA oxidation to remove recalcitrant organic matter from wastewater, comprising ZVI-S modified with ZVI, wherein the surface of the ZVI-S is modified with nickel and copper elements.

[0007] Another objective of this invention is to provide a method for applying a catalyst that mediates H*-activated PAA oxidation to remove recalcitrant organic matter from water.

[0008] Another object of the present invention is to provide an application method for the heterogeneous catalyst described herein to generate H* to inhibit the formation of azo toxic byproducts and nitro toxic byproducts during the oxidative degradation of amino-containing pollutants (such as sulfonamide drugs).

[0009] Another object of the present invention is to provide the application of the heterogeneous Fenton catalyst described herein for activating PAA to oxidatively degrade recalcitrant organic matter in actual pharmaceutical secondary sedimentation tank wastewater.

[0010] To achieve the above objectives, in one technical solution of the present invention, a method for preparing a catalyst for the mediated H*-activated PAA oxidation to remove recalcitrant organic matter from water is provided. The method includes the following steps: ZVI-S is obtained by ball milling ZVI and sulfur powder at a certain molar ratio using mechanical ball milling; then, divalent nickel salt and divalent copper salt are dissolved in ethylene glycol to obtain a mixed solution, and Ni and Cu in the mixed solution are loaded onto the surface of ZVI-S through a hydrothermal reaction; after washing and drying, a heterogeneous catalyst with nickel-copper metal modified on the surface of ZVI-S is obtained.

[0011] Furthermore, the ZVI was purchased commercially and had an average particle size of 40 μm.

[0012] Furthermore, the molar ratio of ZVI to S powder is 0.02~0.1, the ball-to-material ratio is 4:1~12:1, the rotation speed is 300 rpm, and the ball milling time is 2~6 h.

[0013] Furthermore, the divalent nickel salt is selected from NiCl2•6H2O or NiSO4•6H2O, and the divalent copper salt is selected from CuCl2•2H2O or CuSO4 or Cu(NO3)2·3H2O.

[0014] Furthermore, the dosage of sodium acetate is 0.5~2 g, the dosage of polyethylene glycol is 0.1~1 g, and the stirring time is 1~4 h.

[0015] Furthermore, the molar ratio of the metal elements Fe:Ni:Cu in the hydrothermal reaction is 15:3:0 to 15:0:3.

[0016] Furthermore, the hydrothermal reaction temperature is 180~220°C, and the hydrothermal duration is 6-18 h.

[0017] Furthermore, the washing method is as follows: washing with deionized water / ethanol (5:95) 3-6 times; the catalyst is freeze-dried for 6 hours.

[0018] In the preparation method of the heterogeneous catalyst of the present invention, the molar ratio of ZVI to S powder and the molar ratio of Fe:Ni:Cu can be adjusted as needed, and the reaction temperature and hydrothermal duration of the hydrothermal process can also be controlled. Preferred catalysts of the present invention are ZVI-S@Ni2Cu, ZVI-S@NiCu, ZVI-S@Ni, ZVI-S@Cu, and ZVI-S@NiCu2.

[0019] This invention also provides a method for activating a PAA catalyst for the oxidative degradation of wastewater containing recalcitrant organic matter. The method includes: adding a PAA solution to a beaker containing wastewater containing recalcitrant organic matter to be degraded; stirring at 200 rpm; and after thorough mixing, adding the heterogeneous catalyst prepared according to this invention to initiate the degradation reaction. The effect of the heterogeneous catalyst on inhibiting the formation of nitro- and azo-based toxic byproducts during the oxidative degradation of amino-containing pollutants (such as sulfonamides) is evaluated. Results show that the heterogeneous catalyst can rapidly activate PAA to remove various recalcitrant organic matter from water while simultaneously inhibiting the formation of toxic byproducts.

[0020] Furthermore, the molar ratio of the recalcitrant organic compound to the PAA is 5:1 to 40:1.

[0021] Furthermore, the mass concentration of the heterogeneous catalyst added is 0.005-0.4 g / L.

[0022] Furthermore, the pH of the reaction solution is 3-11, and the reaction time is 1-10 min.

[0023] This invention also detected the H* generated by the heterogeneous Fenton catalyst of this invention. This included: the removal rate of the characteristic pollutant 2,4-dichlorophenol (2,4-DCP) by the heterogeneous catalyst, the characteristic spectrum of H* generated by the heterogeneous catalyst in EPR characterization, and the characteristic peak of H* generated by the heterogeneous catalyst detected in the CV curve. It was found that the heterogeneous catalyst prepared by this invention possesses the ability to generate H*.

[0024] The inventors also tested the catalytic effect of the heterogeneous Fenton catalyst of the present invention and found that, in the presence of PAA, the catalyst of the present invention can rapidly, efficiently and continuously remove recalcitrant organic matter from water. The method is used for wastewater containing recalcitrant organic matter, including simulated water distribution and actual secondary sedimentation tank effluent. Therefore, it is a heterogeneous catalyst with excellent performance. Attached Figure Description

[0025] Figure 1 Electron microscopy images, infrared spectra, and XRD patterns of ZVI-S and ZVI-S@Ni2Cu catalysts;

[0026] Figure 2 The effects of heterogeneous catalysts prepared at different Fe:Ni:Cu molar ratios on the oxidative removal of recalcitrant organic pollutants (SMZ) by activated PAA, comparison of the SMZ degradation effects of different systems, degradation effects of ZVI-S@Ni2Cu / PAA on different pollutants, and comparison of the SMZ degradation effects of common transition metal oxides and the heterogeneous catalysts prepared in this invention on activated PAA. (Experimental conditions: [pH]0=7, [heterogeneous catalyst]0=0.1 g / L, [2, 4-DCP]0=50 μM, [recalcitrant organic pollutants]0=10 μM, [PAA]0=0.2 mM);

[0027] Figure 3 The effects of reaction parameters (initial pH, catalyst dosage, PAA dosage) on SMZ degradation efficiency were investigated. (Experimental conditions: [pH]0=7, [ZVI-S@Ni2Cu]0=0.1 g / L, [SMZ]0=10 μM, [PAA]0=0.2 mM).

[0028] Figure 4 The detection of H* generation included the degradation of characteristic contaminants (experimental conditions: [pH]0=7, [ZVI-S@Ni2Cu]0=0.1 g / L, [2, 4-DCP]0=50 μM), EPR spectra, and CV curves.

[0029] Figure 5 Stability experiments (experimental conditions: [pH]0=7, [ZVI-S@Ni2Cu]0=0.1 g / L, [SMZ]0=10 μM, [PAA]0=0.2 mM) and continuous flow experiments were conducted to evaluate the catalytic degradation of SMZ by ZVI-S@Ni2Cu. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the described embodiments are only some embodiments of the present invention, and not all embodiments. For those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0031] Example 1

[0032] Examples of preparation of heterogeneous Fenton reaction catalysts of the present invention

[0033] The preparation method of the heterogeneous Fenton reaction catalyst of the present invention is illustrated by the following examples:

[0034] ZVI and sulfur powder were mixed at a molar ratio of S / Fe of 0.02 to 0.1, and ball-milled at 300 rpm for 2 to 6 h under N2 protection at a ball-to-material ratio of 4:1 to 12:1 to obtain ZVI-S. Divalent nickel salt (NiCl2•6H2O or NiSO4•6H2O) and divalent copper salt (CuCl2•2H2O or CuSO4 or Cu(NO3)2·3H2O) were dissolved in ethylene glycol (50 mL). 0.5–2 g of sodium acetate and 0.1–1 g of polyethylene glycol were added sequentially, and the mixture was stirred continuously for 1–4 h to obtain a mixed solution. The mixed solution and ZVI-S were transferred to a high-pressure reactor and heated at 180–220°C for 6–18 h. After the composite was naturally cooled to room temperature, the solid was separated by centrifugation (6000 rpm) and washed five times with deionized water / ethanol (5:95). The product was collected, freeze-dried under vacuum for 6 h, and ground into powder to obtain ZVI-S@Ni x Cu y Heterogeneous catalyst. Ni x Cu y The preparation method of ZVI-S@Ni x Cu y The catalyst is similar, except that ZVI-S is not added. The ZVI described in this invention is commercially available.

[0035] Structural and compositional analysis of catalyst materials

[0036] The samples obtained in the above preparation examples were analyzed by scanning electron microscopy, and the results are as follows: Figure 1 As shown, the average particle size of ball-milled ZVI-S and ZVI-S@Ni2Cu is 40 μm, while the average particle size of Ni2Cu on the ZVI-S@Ni2Cu surface is only 100 nm.

[0037] The samples obtained in the above preparation examples were subjected to Fourier transform infrared analysis, and the results are as follows: Figure 1 As shown, ZVI-S is at 3405 cm⁻¹. 1 The absorption peak at 1651 cm⁻¹ can be attributed to the OH vibration, while the absorption peak at 1651 cm⁻¹ is attributable to the OH vibration. 1 The wavelength at 2852 cm⁻¹ belongs to the vibration of adsorbed water. After Ni₂Cu modification, the wavelength at 2852 cm⁻¹... 1 A new absorption peak appeared at 626 / 414 cm⁻¹, corresponding to the vibration of Fe-O in the H₂O- anion bridging mode, corresponding to the vibration at 626 / 414 cm⁻¹. 1 A new absorption peak appeared at this point, representing the Ni / Cu-O bond within the Ni2Cu lattice.

[0038] X-ray diffraction pattern analysis was performed on the above samples, and the results are as follows: Figure 1 As shown, ZVI-S and ZVI-S@Ni2Cu exhibit distinct α-Fe peaks at approximately 44.66° and 65.09° (PDF#06-0696), indicating that Fe... 0 It is the main component of ZVI-S based particles. In addition, the content of copper-iron spinel and iron-nickel ore in ZVI-S@Ni2Cu increases, and the α-Fe peak shows a slight positive shift (44.73°). This is due to the strong interaction between Cu / Ni and Fe with different coordinations of -Me-O-Me- / -Me-Me- distributed on octahedrons, tetrahedrons and face-centered cubics.

[0039] Example 2

[0040] The heterogeneous catalyst prepared in this invention is effective in activating PAA to remove recalcitrant organic matter.

[0041] This embodiment prepares an activated PAA oxidative degradation catalyst for drug-containing wastewater. The catalyst is a ZVI-S@Ni2Cu heterogeneous catalyst, and SMZ is selected as the target recalcitrant organic pollutant for oxidative degradation. The specific technical solution is as follows:

[0042] PAA was added to 100 mL of simulated SMZ wastewater (10 μM concentration) at a molar ratio of PAA:SMZ = 10:1. After stirring thoroughly, the pH was adjusted to 7 using 0.1 M HNO3 and 0.1 M NaOH, respectively. 0.02 g of heterogeneous catalyst was added to initiate the degradation reaction. The stirring speed was 200 rpm, and the reaction temperature was 25 ± 2°C. 1 mL samples were collected at predetermined times (0.5, 1, 3, 5, 8, and 10 min), and the SMZ removal rate was used as the evaluation index. The concentration of SMZ was determined by high-performance liquid chromatography (HPLC). The SMZ removal rate was calculated using the following formula:

[0043] y=((C0-C t ) / C0)×100%

[0044] Degradation kinetics were performed using the first-order reaction kinetic equation SMZ, and the apparent reaction rate constant (k) was calculated. obs ):

[0045]

[0046] In the formula, y is the removal rate, C0, C t The concentrations of SMZ at the start of the reaction and at the sampling time are t and k, respectively. obs is the apparent reaction rate constant.

[0047] The control groups were PAA, ZVI-S@Ni2Cu, ZVI-S / PAA, Ni2Cu / PAA, ZVI-S@Ni, ZVI-S@Cu, ZVI-S@NiCu, and ZVI-S@NiCu2. Among them, the ZVI-S@Ni2Cu catalyst showed significantly better activation of PAA for the oxidative degradation of SMZ than the other control groups, achieving a 90.8% removal rate of SMZ within 10 minutes. obs It is 0.3501 minˉ 1 (like Figure 2 The ZVI-S@Ni2Cu catalyst is significantly more effective than existing transition metal oxides (Co, Mn, Fe, Cu) in activating PAA and oxidatively degrading SMZ.

[0048] Example 3

[0049] The heterogeneous catalyst prepared in this invention inhibits the production of azo- and nitro-toxic byproducts during the oxidative degradation of amino-containing pollutants (such as sulfonamides).

[0050] This embodiment prepares an activated PAA oxidative degradation catalyst for drug-containing wastewater. The catalyst is a ZVI-S@Ni2Cu heterogeneous catalyst. Using this catalyst, SMZ was selected as the target drug for oxidative degradation. The degradation products were measured, and the control effect on nitro-toxic and coupled toxic byproducts was evaluated. The specific technical solution is as follows:

[0051] PAA was added to 100 mL of simulated SMZ wastewater (10 μM concentration) at a molar ratio of PAA:SMZ = 10:1. After stirring, the pH was adjusted to 7 using 0.1 M HNO3 and 0.1 M NaOH, respectively. 0.02 g of ZVI-S@Ni2Cu catalyst was added to initiate the degradation reaction. The stirring speed was 200 rpm, and the reaction temperature was 25 ± 2°C. After 5 min of reaction, 1 mL of sample was collected. The degradation products of SMZ were determined by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS). The comparative sample was a typical Co... 2+ / PAA system. The results are shown in the table below. No nitro toxic byproducts or coupling toxic byproducts were detected in the ZVI-S@Ni2Cu / PAA system.

[0052] Table 1 Co 2+ Comparison of SMZ degradation products between the / PAA system and the ZVI-S@Ni2Cu / PAA system

[0053] <![CDATA[Co 2+ / Products of the PAA system]]> <![CDATA[Products of the ZVI-S@Ni2Cu / PAA system]]> (Nitro products) (Nitro products) (Azo products) (Azo products)

[0054] Example 4

[0055] The heterogeneous catalyst prepared in this invention is effective in removing various recalcitrant organic compounds by activating PAA.

[0056] This embodiment prepares an activated PAA oxidative degradation catalyst for drug-containing wastewater. The catalyst is a ZVI-S@Ni2Cu heterogeneous catalyst, and TC and NAP were selected as target drugs for oxidative degradation using this catalyst. The specific technical solution is as follows:

[0057] PAA was added to 100 mL of TC wastewater (10 μM concentration) at a molar ratio of PAA:SMZ = 10:1 in a beaker. Another set of beakers contained NAP wastewater (10 μM concentration). After thorough mixing, the pH was adjusted to 7 using 0.1 M HNO3 and 0.1 M NaOH, respectively. 0.02 g of ZVI-S@Ni2Cu catalyst was added to initiate the degradation reaction. The stirring speed was 200 rpm, and the reaction temperature was 25 ± 2°C. Samples of 1 mL were collected at predetermined times (0.5, 1, 3, 5, 8, and 10 min), with TC removal rate as the evaluation index. The concentrations of TC and NAP were determined by HPLC. The effect of ZVI-S@Ni2Cu catalyst in activating PAA for oxidative degradation of TC and NAP is as follows: Figure 2 As shown, the removal rate of TC was 93.4% within 10 minutes, and k obs It is 0.3725 minˉ 1 Within 8 minutes, the removal rate of NAP was 100.0%, k obs It is 0.4064 minˉ 1 .

[0058] Example 5

[0059] Optimization of reaction conditions for the removal of various recalcitrant organic compounds using the heterogeneous catalyst / PAA prepared in this invention.

[0060] This embodiment prepares an activated PAA oxidative degradation catalyst for drug-containing wastewater. The catalyst is a ZVI-S@Ni2Cu heterogeneous catalyst, and SMZ was selected as the target drug for oxidative degradation. The degradation reaction conditions (pH, ZVI-S@Ni2Cu catalyst dosage, and PAA dosage) were optimized. The specific technical solution is as follows:

[0061] PAA was added to a 100 mL beaker containing simulated SMZ wastewater (10 μM concentration) at a PAA:SMZ ratio of 10:1 (molar ratio). After stirring, the pH was adjusted to 3, 5, 7, 9, and 11 using 0.1 M HNO3 and 0.1 M NaOH, respectively. 0.02 g of ZVI-S@Ni2Cu catalyst was then added to each beaker to initiate the degradation reaction. The stirring speed was 200 rpm, and the reaction temperature was 25 ± 2°C. 1 mL samples were collected at predetermined times (0.5, 1, 3, 5, 8, and 10 min), with the SMZ removal rate used as the evaluation index. The concentration of SMZ was determined by HPLC. The effect of ZVI-S@Ni2Cu catalyst in activating PAA for oxidative degradation of SMZ is as follows: Figure 3 As shown, the removal rate of SMZ was greater than 80.2% in the pH range of 3–9.

[0062] PAA was added to 100 mL of simulated SMZ wastewater (10 μM concentration) at a molar ratio of PAA:SMZ = 10:1. After stirring, the pH was adjusted to 7 using 0.1 M HNO3 and 0.1 M NaOH, respectively. ZVI-S@Ni2Cu catalyst was then added at 0.005 g, 0.01 g, 0.02 g, and 0.04 g to initiate the degradation reaction. The stirring speed was 200 rpm, and the reaction temperature was 25 ± 2°C. 1 mL samples were collected at predetermined times (0.5, 1, 3, 5, 8, and 10 min), with the SMZ removal rate used as the evaluation index. The concentration of SMZ was determined by HPLC. The effect of ZVI-S@Ni2Cu catalyst in activating PAA for oxidative degradation of SMZ is as follows: Figure 3 As shown, when the dosage of ZVI-S@Ni2Cu was increased to 0.2 g / L, the removal rate of SMZ reached 100.0% within 8 min.

[0063] PAA was added to 100 mL of simulated SMZ wastewater (10 μM concentration) at PAA:SMZ ratios of 2:1, 5:1, 10:1, 20:1, and 40:1 (molar ratio). After stirring, the pH was adjusted to 7 using 0.1 M HNO3 and 0.1 M NaOH, respectively. 0.02 g of ZVI-S@Ni2Cu catalyst was added to initiate the degradation reaction. The stirring speed was 200 rpm, and the reaction temperature was 25 ± 2°C. 1 mL samples were collected at predetermined times (0.5, 1, 3, 5, 8, and 10 min), with the SMZ removal rate used as the evaluation index. The concentration of SMZ was determined by HPLC. Figure 3 As shown, when the PAA:SMZ ratio is increased to 40:1, the removal rate of SMZ reaches 98.5% within 8 minutes.

[0064] Example 6

[0065] H* generation detection of the heterogeneous catalyst prepared in this invention

[0066] This embodiment prepares an activated PAA oxidative degradation catalyst for drug-containing wastewater, which is a ZVI-S@Ni2Cu heterogeneous catalyst. Using this catalyst, the generation of H* was detected. The specific technical solution is as follows:

[0067] Add 100 mL of 10 μM 2,4-DCP wastewater to be treated to a beaker, stir well, and adjust the pH to 7 using 0.1 M HNO3 and 0.1 M NaOH, respectively. Initiate the catalytic reaction by adding 0.02 g ZVI-S@Ni2Cu catalyst. The stirring speed is 200 rpm, and the reaction temperature is 25 ± 2°C. Collect 1 mL of sample at predetermined times, using the 2,4-DCP removal rate as the evaluation index. The concentration of 2,4-DCP is determined by HPLC. Figure 4 As shown, in the control group, tert-butanol and methanol were added to quench H*, in addition to the ZVI-S@Ni2Cu catalyst. The removal rate of 2,4-DCP significantly decreased in the groups with added tert-butanol and methanol. Furthermore, EPR characterization and CV curves detected the characteristic spectrum of H* generation by the ZVI-S@Ni2Cu catalyst, indicating that the ZVI-S@Ni2Cu catalyst possesses the ability to generate H*. Moreover, the signal intensity of H* in the ZVI-S@Ni2Cu system exceeded that of all comparative material systems, demonstrating that ZVI-S@Ni2Cu can generate more H*.

[0068] Example 7

[0069] Stability testing of the heterogeneous catalyst prepared in this invention

[0070] This embodiment prepares an activated PAA oxidative degradation catalyst for drug-containing wastewater, which is a ZVI-S@Ni2Cu heterogeneous catalyst. Using this catalyst, SMZ was selected as the target drug for oxidative degradation. After the reaction, the ZVI-S@Ni2Cu heterogeneous catalyst was recovered for recycling experiments. The specific technical solution is as follows:

[0071] The stability of the ZVI-S@Ni2Cu heterogeneous catalyst was evaluated by repeating the experiment five times. After each reaction, the solid was separated by centrifugation, and the ZVI-S@Ni2Cu heterogeneous catalyst was washed with ethanol and deionized water. ZVI-S@Ni2Cu was then recovered by freeze-drying. Five cycles of the experiment were conducted under the same reaction conditions. Figure 5 As shown, after repeating the process 5 times, the removal efficiency of SMZ was still above 81.1%, and the leaching rates of metallic iron, nickel, and copper during the cycle were also lower than the limits of the national standard (GT 31962-2015).

[0072] Example 8

[0073] The heterogeneous catalyst prepared in this invention demonstrates its effectiveness in activating PAA to remove recalcitrant organic matter from actual wastewater.

[0074] This embodiment prepares an activated PAA oxidative degradation catalyst for drug-containing wastewater. The catalyst is a ZVI-S@Ni2Cu heterogeneous catalyst. Using this catalyst, SMZ was selected as the target drug for oxidative degradation. Long-term continuous flow experiments were conducted in simulated wastewater, actual pharmaceutical secondary sedimentation tank effluent 1, and pharmaceutical secondary sedimentation tank effluent 2. The specific technical solution is as follows:

[0075] The influent to the long-term continuous flow reactor contained SMZ solution (10 μM) and PAA solution (2 mM) at a flow rate of 5 mL / min. The fluidized bed reactor contained ZVI-S@Ni2Cu catalyst (0.2 g / L), and the catalyst was filtered through titanium aerators. The effluent was collected. The SMZ removal rates in the tap water, pharmaceutical secondary sedimentation tank effluent 1, and pharmaceutical secondary sedimentation tank effluent 2 systems were all greater than 90%, and the systems operated stably in the fluidized bed reactor for 520, 470, and 300 min, respectively. The ZVI-S@Ni2Cu / PAA system demonstrates superior ability in continuous SMZ treatment.

[0076] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0077] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A novel heterogeneous Fenton catalyst comprising zero-valent iron sulfide (ZVI-S), wherein the surface of the ZVI-S is modified with nickel-copper metal, and the heterogeneous catalyst comprises the following preparation steps: ZVI and sulfur powder are ball-milled at 300 rpm for 2-6 h under N2 protection at a molar ratio of S / Fe of 0.02-0.1 and a ball-to-material ratio of 4:1-12:

1. Divalent nickel salt and divalent copper salt were dissolved in ethylene glycol (50 mL), and 0.5-2 g sodium acetate and 0.1-1 g polyethylene glycol were added sequentially. After stirring continuously for 1-4 h, a mixed solution was obtained. The mixed solution and ZVI-S were transferred to a high-pressure reactor. The molar ratio of metal elements Fe:Ni:Cu in the hydrothermal reaction was 15:3:0-15:0:

3. Then, the reactor was heated at 180-220°C for 6-18 h. After the composite was naturally cooled to room temperature, the solid was separated by centrifugation (6000 rpm) and washed 5 times with deionized water / ethanol (5:95). The product was collected, freeze-dried under vacuum for 6 h, and ground into powder.

2. The heterogeneous Fenton catalyst according to claim 1, wherein the divalent nickel salt is selected from NiCl2•6H2O or NiSO4•6H2O, and the divalent copper salt is selected from CuCl2•2H2O or CuSO4 or Cu(NO3)2·3H2O.

3. The use of the novel heterogeneous Fenton catalyst of the present invention activated peracetic acid in the treatment of recalcitrant organic matter in water according to claim 1 or 2.

4. The use of the novel heterogeneous Fenton catalyst of the present invention, according to claim 1 or 2, to generate H* to inhibit the formation of nitro toxic byproducts and azo toxic byproducts during the degradation of amino-containing pollutants (such as sulfonamide drugs).

5. The use of the novel heterogeneous Fenton catalyst of the present invention, according to claim 1 or 2, for activating PAA to oxidize and degrade recalcitrant organic matter in actual wastewater.

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