A method for constructing a dual active site Fe (FeS) C / PI catalytic oxidation wastewater system

Abstract

This invention discloses a method for constructing a Fe(FeS)C / PI catalytic oxidation system for wastewater with dual active sites. This system uses iron-based metal-organic frameworks (Fe-MOFs) as precursors, and obtains a Fe(FeS)C ternary composite structure through solvothermal reaction and calcination. This structure is then added to a mixed solution of PI and 2,4-dichlorophenol. In this invention, zero-valent iron (FeS)C is used as the precursor. 0 ) serves as the core active site, through valence cycling (Fe 2+ / Fe 3+ Activation of PI to generate IO3 ‑ And high-valence iron-oxygen species, while FeS regulates electronic structure and promotes Fe 2+ The invention regenerates and enhances PI adsorption, with the carbon skeleton serving as a conductive carrier to disperse active sites and inhibit aggregation. The preparation method of this invention is simple and the process is easy to control. The constructed catalytic oxidation wastewater system can achieve a 100% removal rate of 2,4-dichlorophenol in the pH range of 3 to 9, and has strong resistance to anion interference, combining heterogeneous catalytic stability and environmental friendliness.

Description

Technical Field

[0001] This invention belongs to the field of environmental remediation and catalytic material preparation, and relates to a method for constructing a dual-active-site Fe(FeS)C / PI catalytic oxidation system for wastewater. Background Technology

[0002] With the acceleration of global industrialization, the pollution of water bodies by organic pollutants is becoming increasingly serious. 2,4-Dichlorophenol, a typical chlorophenol compound, is widely used in pesticides, pharmaceuticals, and dyes. It is characterized by high toxicity, recalcitrant degradation, and bioaccumulation, and has been listed as a priority pollutant for control by my country's Ministry of Ecology and Environment. Traditional biological and physical methods for treating 2,4-dichlorophenol suffer from slow degradation rates and incomplete mineralization. However, advanced oxidation processes (AOPs) in chemical methods can generate ·OH groups, which... 1 Strong oxidizing species such as O2 have become a current research hotspot.

[0003] Advanced oxidation techniques for periodate (PI) (PI-AOPs) have attracted widespread attention in recent years due to the advantages of inexpensive and readily available oxidants, high stability, and ease of storage and transportation. The standard redox potential of PI is 1.6V, but its individual oxidation ability is relatively weak, requiring activation methods (such as photocatalysis, ultrasound, and metal catalysis) to enhance its reactivity. Traditional homogeneous catalysts (such as Fe) 2+ While it can activate PI to generate active species, it suffers from drawbacks such as a narrow pH range (usually effective only under acidic conditions), easy dissolution of iron ions leading to secondary pollution, and difficulty in recovery. Although the development of heterogeneous catalysts (such as zero-valent iron and metal sulfides) can reduce ion dissolution through solid-liquid interface reactions and achieve catalyst reuse, it still has substantial drawbacks, such as low electron transfer efficiency leading to slow PI activation rates and incomplete pollutant degradation; and the easy oxidation of metal sulfides during the reaction, leading to sulfur dioxide (S) degradation. 2- Release, accompanied by the dissolution of metal ions, causes water pollution; under neutral or alkaline conditions, metal sites are easily hydrolyzed to form hydroxide precipitates, leading to catalyst deactivation; after multiple cycles, the activity of the catalyst decreases significantly, due to surface structure damage, loss of active sites, or blockage caused by pollutant adsorption.

[0004] Therefore, the present invention aims to provide a method for catalytic oxidation of wastewater to solve the above-mentioned problems. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention aims to provide a method for constructing a Fe(FeS)C / PI catalytic oxidation system for wastewater with dual active sites. This system utilizes iron-based metal-organic frameworks (Fe-MOFs) as precursors, and after solvothermal reaction and calcination to obtain a Fe(FeS)C ternary composite structure, it is then added to a mixed solution of PI and 2,4-dichlorophenol. In this invention, zero-valent iron (FeS)C is used... 0 ) serves as the core active site, through valence cycling (Fe 2+ / Fe 3+ Activation of PI to generate IO3 - And high-valence iron-oxygen species, while FeS regulates electronic structure and promotes Fe 2+ The invention regenerates and enhances PI adsorption, with the carbon skeleton serving as a conductive carrier to disperse active sites and inhibit aggregation. The preparation method of this invention is simple and the process is easy to control. The constructed catalytic oxidation wastewater system can achieve a 100% removal rate of 2,4-dichlorophenol in the pH range of 3 to 9, and has strong resistance to anion interference, combining heterogeneous catalytic stability and environmental friendliness.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for constructing a Fe(FeS)C / PI catalytic oxidation system for wastewater with dual active sites is carried out in the following order:

[0008] S1. Preparation of Fe(FeS)C catalyst

[0009] Ferric chloride and 2,5-thiophene dicarboxylic acid were added to dimethylformamide and mixed evenly. Then acetic acid was added, and the mixture was placed in a reaction vessel and reacted at 120°C for 24 hours. After washing three times with anhydrous ethanol, centrifuging and drying, the mixture was placed in a tube furnace and calcined under an inert gas atmosphere to obtain the Fe(FeS)C catalyst.

[0010] S2, Construction of catalytic oxidation wastewater system

[0011] PI was added to 2,4-dichlorophenol, and sulfuric acid and sodium hydroxide were added to adjust the pH to 3-9. Then, Fe(FeS)C catalyst was added to obtain a catalytic oxidation wastewater system.

[0012] As a limitation of the present invention, in step S1, the molar ratio between ferric chloride and 2,5-thiophene dicarboxylic acid, dimethylformamide and acetic acid is (10-15):(8-10):(385-400):(50-60).

[0013] In this invention, the molar ratio between ferric chloride and 2,5-thiophene dicarboxylic acid, dimethylformamide, and acetic acid is crucial. When the molar ratio is within this range, it promotes the formation of a well-structured Fe-MOF precursor with uniformly dispersed metal sites. If the molar ratio is less than this, it will result in insufficient material ratio or excessive solvent, leading to uneven distribution of active components in the calcined Fe(FeS)C catalyst, a reduction in the number of catalytic active sites, decreased activation efficiency for PI, and poorer pollutant degradation. If the molar ratio is greater than this, it will result in excessive material, agglomeration of metal ions in the precursor, and blockage of pores, resulting in severe particle agglomeration in the calcined Fe(FeS)C catalyst. The carbon support cannot effectively disperse active sites, electron transfer is hindered, catalytic activity is reduced, and stability decreases.

[0014] As a second limitation of the present invention, in step S1, the centrifugation speed is 9000-12000 rpm and the time is 5-10 min.

[0015] As a third limitation of the present invention, in step S1, the drying temperature is 80-100°C and the time is 12-16 hours.

[0016] As a fourth limitation of the present invention, in step S1, the calcination is performed sequentially according to the following procedure:

[0017] (a) In the first heating stage, the temperature is increased from room temperature to 450-550℃ at a heating rate of 5-10℃ / min, and held for 1-2 hours;

[0018] (b) In the second heating stage, the temperature is increased from 450-550℃ to 700-900℃ at a heating rate of 5-10℃ / min, and held for 1-2 hours;

[0019] (c) Cooling stage: The furnace is cooled to room temperature.

[0020] In this invention, the calcination process affects the decomposition of Fe-MOFs precursors, the formation of the carbon skeleton, and the transformation of Fe(FeS) active species. In the first heating stage, when the temperature is increased from room temperature to 450-550°C at a heating rate of 5-10°C / min, the organic ligands in the Fe-MOFs precursors will decompose and undergo preliminary carbonization. Fe species will begin to undergo valence state transformation and form a small amount of FeS. If the heating rate is less than 5°C / min in this stage, the decomposition of organic ligands will be too slow, resulting in excessive local carbon deposition, which will cause the active sites to be encapsulated and the subsequent dispersibility of Fe(FeS) species will be poor. If the heating rate is greater than 10°C / min, the decomposition of organic ligands will be incomplete and local high temperatures will be generated, which will cause the carbon skeleton structure to collapse and some Fe species to agglomerate. The initial holding time of 1–2 hours ensures the complete decomposition of organic ligands, laying the foundation for the subsequent stable formation of the carbon framework and the transformation of Fe (FeS) species. Holding time less than 1 hour will result in residual organic ligands, affecting subsequent carbonization and Fe species transformation. Holding time greater than 2 hours will cause over-carbonization, with the carbon layer thickening hindering the exposure of active sites. In the second heating stage, when the temperature is increased from 450–550℃ to 700–900℃ at a rate of 5–10℃ / min, the carbon framework will further graphitize, and the Fe species will be completely transformed into Fe. 0 And FeS, and uniformly dispersed in the carbon matrix; if the heating rate is less than 5℃ / min during this stage, it will cause Fe 0 Excessive growth of FeS crystallites leads to a reduction in the number of active sites and a decrease in catalytic activity; if the heating rate exceeds 10℃ / min, it will cause Fe... 0 Uneven FeS distribution and increased defects in the carbon framework structure lead to decreased material stability and easy loss of active species. Holding at this stage for 1-2 hours is to promote Fe... 0 The Fe(FeS) crystal phase forms stably, enhancing the bonding force between the carbon framework and active species. If the holding time is less than 1 hour, the Fe(FeS) crystal phase will not develop completely, resulting in insufficient catalytic activity; if the holding time is greater than 2 hours, the Fe(FeS) crystal phase will not develop properly, resulting in insufficient catalytic activity. 0 Excessive oxidation destroys the FeS phase structure.

[0021] As a fifth limitation of the present invention, in step S2, the molar ratio between PI and 2,4-dichlorophenol and Fe(FeS)C is (1-3):(0.061-0.0615):(0.8-0.85).

[0022] In this invention, the molar ratio of PI to 2,4-dichlorophenol and Fe(FeS)C affects the degradation efficiency of pollutants, the amount of active species generated, and the catalyst utilization rate of the catalytic oxidation system. When the molar ratio is within this range, efficient activation of PI and complete degradation of pollutants are achieved, the active sites of the Fe(FeS)C catalyst are fully utilized, and the amount of active species generated in the system is moderate and consistently stable. If the molar ratio is greater than this range, it will lead to an excess of PI or a relative deficiency of catalyst. Excess PI cannot be effectively activated and instead undergoes a quenching reaction with the active species, resulting in a decrease in the utilization rate of active species, a negligible or even reduced improvement in pollutant degradation efficiency, and waste of oxidant. If the molar ratio is less than this range, it will lead to insufficient PI or an excess of catalyst. The active sites of the catalyst cannot fully function, the amount of active species generated is insufficient, resulting in incomplete degradation of 2,4-dichlorophenol, a significantly reduced removal rate, and low catalyst utilization.

[0023] This invention also provides an application of Fe(FeS)C, in which the prepared Fe(FeS)C can be used as a catalyst in the catalytic oxidation of wastewater systems to remove 2,4-dichlorophenol from wastewater.

[0024] This invention utilizes iron-based metal-organic frameworks (Fe-MOFs) as precursors, and prepares Fe(FeS)C composite catalysts through solvothermal reaction and calcination, thereby constructing a highly efficient and stable Fe(FeS)C / PI catalytic oxidation system for wastewater. Fe-MOFs possess extremely high specific surface area and abundant mesopores, providing ample contact space for active sites in the catalytic reaction. They also exhibit tunable pore structures and highly dispersed metal sites, ensuring uniform distribution of components in the pyrolysis-derived Fe(FeS)C composite catalyst and preventing the aggregation of active species. Furthermore, the carbon framework enhances the material's conductivity and structural stability; the porous network structure uniformly disperses and encapsulates the active components, effectively inhibiting particle aggregation and preventing deactivation of active sites due to aggregation. It also resists oxidative corrosion of PI and active species in the reaction system, protecting the Fe / FeS active centers from direct attack; and reduces excessive adsorption of 2,4-dichlorophenol and its degradation intermediates on the catalyst surface, preventing pore blockage. In this system, zero-valent iron (Fe... 0 As the core active component, it dominates electron transfer in the system, providing electrons for the catalytic reaction, and then through valence state cycling (Fe) 2+ / Fe 3+ Activation of PI to generate IO3 - And high-priced iron-oxygen species. First, Fe 0 It loses electrons and is oxidized to Fe. 2 + This provides the system with initial electrons; subsequently, Fe... 2+ As a key intermediate and PI (IO4) -) reacts, Fe 2+ Oxidized to Fe 3+ Meanwhile, IO4 - Restored to IO3 - During this process, some Fe 3+ Under a locally highly oxidizing environment, high-valence ferric oxygen species are further generated; finally, Fe... 3+ By accepting Fe 0 Or the electrons transferred by FeS are reduced to Fe. 2+ Complete "Fe 0 →Fe 2+ →Fe 3+ →Fe 2+ The valence state cycle of FeS. FeS modulates the electronic structure, interacting with Fe. 0 A synergistic effect is formed: sulfur combines with Fe to form FeS, which reduces the electron density of Fe sites and enhances their adsorption capacity for PI. 0 Provides the main electron source, while sulfur vacancies or S in FeS 2- It can act as a secondary electron donor, releasing electrons through oxidation reactions to assist Fe. 3+ Reduced to Fe 2+ Accelerate Fe 2+ Regeneration, and the presence of FeS can optimize Fe 0 Surface electron distribution reduces Fe 0 Excessive oxidation of FeS helps maintain its electron-supplying capacity. Furthermore, the porous structure and surface charge properties of FeS enhance the physical adsorption of PI and increase IO4. - The enrichment concentration on the catalyst surface promotes the activation reaction; the carbon skeleton acts as a conductive support, dispersing active sites and inhibiting aggregation.

[0025] The main active species in this catalytic oxidation wastewater system is singlet oxygen. 1 O2), hydroxyl radicals (·OH) and superoxide radicals (·O2) - ),in 1 O2 dominates pollutant degradation via the PI activation pathway (IO4). - →·O2 - →H2O2→·OH) achieves synergistic oxidation, ·O2 - It mainly participates in the generation of active species as an intermediate, and it can be converted into IO4. - The single-electron reduction to generate (IO4) - +e - =IO3 - +·O2 - ), then O2 - Further reaction produces H2O2(2·O2) - +2H +=H₂O₂ + O₂) provides a precursor for the formation of ·OH; ·OH has strong oxidizing properties (redox potential of approximately 2.8V), and can directly attack the chemical bonds (such as C-Cl bonds and C-C bonds) in pollutant molecules, decomposing them into small molecule intermediates. ·O₂ - To ensure the continuity of bioactive species generation, ·OH enhances the direct oxidation of recalcitrant pollutants. 1 O2 dominates the overall degradation process, and the three factors together cover different stages of pollutant degradation, improving the system's mineralization efficiency for complex organic pollutants.

[0026] The above-mentioned technical solution of the present invention is a whole in which each step is closely related and mutually influential, and together they determine the morphological characteristics and performance of the product.

[0027] The above technical solution has the following advantages or beneficial effects:

[0028] 1. This invention uses Fe-MOFs as a precursor and prepares Fe(FeS)C composite catalyst through solvothermal reaction combined with calcination treatment to achieve synergy between Fe(FeS) active sites and carbon support, thereby activating PI and improving the removal rate of 2,4-dichlorophenol in wastewater.

[0029] 2. This invention constructs a ternary heterogeneous catalytic system of "zero-valent metal-sulfide-carbon", overcoming the problem of homogeneous catalyst recovery and resisting Cl. - HCO3 - It is resistant to interference from anions and different water qualities, has a wide range of applications, and is highly stable.

[0030] 3. The preparation method of this invention is simple, the process is easy to control, and it is suitable for large-scale industrial production.

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0032] Figure 1 The images shown are scanning electron microscope (SEM) images of Fe-MOFs prepared in Example 1 of this invention, wherein: (a) is an overall morphology image of Fe-MOFs at low magnification, (b) is a surface microstructure image of Fe-MOFs aggregates at high magnification, and (c) is a local aggregation morphology image of Fe-MOFs at medium magnification.

[0033] Figure 2 The XRD pattern of Fe(FeS)C prepared in Example 1 of this invention;

[0034] Figure 3The diagram shows the removal effect of the catalytic oxidation wastewater system constructed in Example 1, Comparative Example 1, and Comparative Example 2 on 2,4-dichlorophenol.

[0035] Figure 4 Fe dissolved from the catalytic oxidation wastewater system constructed in Example 1 and Comparative Example 1 of this invention 2+ Concentration graph;

[0036] Figure 5 This is a graph showing the total iron concentration dissolved in the catalytic oxidation wastewater system constructed in Example 1 and Comparative Example 1 of the present invention;

[0037] Figure 6 The diagram shows the removal effect of the catalytic oxidation wastewater system constructed in Examples 1-4 of this invention on 2,4-dichlorophenol.

[0038] Figure 7 The diagram shows the removal effect of the catalytic oxidation wastewater system constructed in Example 5 of this invention on different pollutants.

[0039] Figure 8 The figure shows the removal effect of the catalytic oxidation wastewater system constructed in Example 6 of the present invention on 2,4-dichlorophenol in different water qualities.

[0040] Figure 9 The figure shows the removal effect of the catalytic oxidation wastewater system constructed in Example 1 of this invention on 2,4-dichlorophenol under different anion conditions.

[0041] Figure 10 The figure shows the removal effect of the catalytic oxidation wastewater system constructed in Example 1 of this invention on 2,4-dichlorophenol in different capture agents. Detailed Implementation

[0042] The following embodiments are merely some, not all, of the embodiments of the present invention. Therefore, the detailed descriptions of the embodiments provided below are not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0043] In this invention, unless otherwise specified, all equipment and raw materials are commercially available or commonly used in the industry. The methods described in the following embodiments are conventional methods in the art, unless otherwise specified.

[0044] Example 1

[0045] This embodiment constructs a catalytic oxidation wastewater system, and its preparation process and steps are as follows:

[0046] S1. Preparation of Fe(FeS)C catalyst

[0047] 0.010 mol ferric chloride and 0.008 mol 2,5-thiophene dicarboxylic acid were added to 0.385 mol dimethylformamide and mixed thoroughly. Then, 0.050 mol acetic acid was added, and the mixture was placed in a reactor and reacted at 120 °C for 24 h. The mixture was washed three times with anhydrous ethanol, centrifuged at 9000 rpm for 5 min, dried at 80 °C for 12 h, and finally placed in a tube furnace. Under an inert gas atmosphere, the temperature was increased from room temperature to 450 °C at a heating rate of 5 °C / min and held for 1 h. Then, the temperature was increased from 450 °C to 700 °C at a heating rate of 5 °C / min and held for 1 h to obtain the Fe(FeS)C catalyst.

[0048] S2, Construction of catalytic oxidation wastewater system

[0049] Add 0.001 mol PI to 6.10 × 10 -5 In 2,4-dichlorophenol wastewater (the concentration of 2,4-dichlorophenol wastewater is 10 mg / L, which is obtained by dissolving 2,4-dichlorophenol in deionized water), after adjusting the pH to 3 with sulfuric acid and sodium hydroxide, 8.0 × 10⁻⁶ mg / L of the solution was added. -4 A wastewater catalytic oxidation system was obtained by using mol Fe(FeS)C catalyst.

[0050] Example 2

[0051] This embodiment constructs a catalytic oxidation wastewater system, and its preparation process and steps are as follows:

[0052] S1. Preparation of Fe(FeS)C catalyst

[0053] 0.012 mol ferric chloride and 0.009 mol 2,5-thiophene dicarboxylic acid were added to 0.392 mol dimethylformamide and mixed thoroughly. Then, 0.055 mol acetic acid was added, and the mixture was placed in a reactor and reacted at 120 °C for 24 h. The mixture was washed three times with anhydrous ethanol, centrifuged at 12000 rpm for 8 min, dried at 100 °C for 14 h, and finally placed in a tube furnace. Under an inert gas atmosphere, the temperature was increased from room temperature to 500 °C at a rate of 10 °C / min and held for 1.5 h. Then, the temperature was increased from 500 °C to 800 °C at a rate of 10 °C / min and held for 1.5 h to obtain the Fe(FeS)C catalyst.

[0054] S2, Construction of catalytic oxidation wastewater system

[0055] Add 0.002 mol PI to 6.13 × 10 -5In 2,4-dichlorophenol wastewater (the concentration of 2,4-dichlorophenol wastewater is 10 mg / L, which is obtained by dissolving 2,4-dichlorophenol in deionized water), after adjusting the pH to 5 with sodium hydroxide and sulfuric acid, 8.15 × 10⁻⁶ mg / L of sodium hydroxide was added. -4 A wastewater catalytic oxidation system was obtained by using mol Fe(FeS)C catalyst.

[0056] Example 3

[0057] This embodiment constructs a catalytic oxidation wastewater system, and its preparation process and steps are as follows:

[0058] S1. Preparation of Fe(FeS)C catalyst

[0059] 0.015 mol ferric chloride and 0.010 mol 2,5-thiophene dicarboxylic acid were added to 0.400 mol dimethylformamide and mixed thoroughly. Then, 0.060 mol acetic acid was added, and the mixture was placed in a reactor and reacted at 120 °C for 24 h. The mixture was washed three times with anhydrous ethanol, centrifuged at 10000 rpm for 10 min, dried at 90 °C for 16 h, and finally placed in a tube furnace. Under an inert gas atmosphere, the temperature was increased from room temperature to 550 °C at a heating rate of 8 °C / min and held for 2 h. Then, the temperature was increased from 550 °C to 900 °C at a heating rate of 8 °C / min and held for 2 h to obtain the Fe(FeS)C catalyst.

[0060] S2, Construction of catalytic oxidation wastewater system

[0061] Add 0.003 mol PI to 6.15 × 10 -5 In 2,4-dichlorophenol wastewater (the concentration of 2,4-dichlorophenol wastewater is 10 mg / L, which is obtained by dissolving 2,4-dichlorophenol in deionized water), after adjusting the pH to 7 with sodium hydroxide and sulfuric acid, 8.5 × 10⁻⁶ mg / L of sodium hydroxide was added. -4 A wastewater catalytic oxidation system was obtained by using mol Fe(FeS)C catalyst.

[0062] Example 4

[0063] This embodiment constructs a catalytic oxidation wastewater system, and its preparation process and steps are as follows:

[0064] S1. Preparation of Fe(FeS)C catalyst

[0065] 0.015 mol ferric chloride and 0.010 mol 2,5-thiophene dicarboxylic acid were added to 0.400 mol dimethylformamide and mixed thoroughly. Then, 0.060 mol acetic acid was added, and the mixture was placed in a reactor and reacted at 120 °C for 24 h. The mixture was washed three times with anhydrous ethanol, centrifuged at 12000 rpm for 5 min, dried at 100 °C for 12 h, and finally placed in a tube furnace. Under an inert gas atmosphere, the temperature was increased from room temperature to 450 °C at a rate of 10 °C / min and held for 1 h. Then, the temperature was increased from 450 °C to 900 °C at a rate of 5 °C / min and held for 2 h to obtain the Fe(FeS)C catalyst.

[0066] S2, Construction of catalytic oxidation wastewater system

[0067] Add 0.001 mol PI to 6.10 × 10 -5 In 2,4-dichlorophenol wastewater (the concentration of 2,4-dichlorophenol wastewater is 10 mg / L, which is obtained by dissolving 2,4-dichlorophenol in deionized water), after adjusting the pH to 9 with sulfuric acid and sodium hydroxide, 8 × 10⁻⁶ mg / L of sodium hydroxide was added. -4 A wastewater catalytic oxidation system was obtained by using mol Fe(FeS)C catalyst.

[0068] Example 5

[0069] This embodiment constructs a catalytic oxidation wastewater system, the process of which is similar to that of Example 1, except that the wastewater added in step S2 is different, i.e., the pollutants contained in the wastewater are different. The wastewater preparation steps are the same as in Example 1, as follows:

[0070] Group A: Wastewater without 2,4-dichlorophenol, wastewater with Rhodamine B added;

[0071] Group B: Wastewater without 2,4-dichlorophenol, wastewater with methylene blue added;

[0072] Group C: Wastewater without 2,4-dichlorophenol, wastewater with sulfadimethylpyrimidine.

[0073] Example 6

[0074] This embodiment constructs a catalytic oxidation wastewater system, the process of which is similar to that of Example 1, except that in step S2, the solvent used to prepare 2,4-dichlorophenol wastewater is different. All other parameters are the same as in Example 1, as detailed below:

[0075] Group A: Do not use deionized water, use tap water, that is, dissolve 2,4-dichlorophenol in tap water to form 2,4-dichlorophenol wastewater;

[0076] Group B: Instead of using deionized water, lake water is used, that is, 2,4-dichlorophenol is dissolved in lake water to form 2,4-dichlorophenol wastewater;

[0077] Group C: Instead of using deionized water, seawater is used, that is, 2,4-dichlorophenol is dissolved in seawater to form 2,4-dichlorophenol wastewater.

[0078] Comparative Example

[0079] To investigate the effect of catalysts similar to those used in this invention on the removal of 2,4-dichlorophenol, the following comparative experiments were conducted, as detailed below:

[0080] Comparative Example 1

[0081] This comparative example constructs a catalytic oxidation system for wastewater. The preparation process is similar to that of Example 1, except that the catalyst used in step S2 is different, as detailed below:

[0082] Group A: No PI added, i.e., Fe(FeS)C used alone;

[0083] Group B: No Fe(FeS)C catalyst was added, i.e., PI was used alone;

[0084] Group C: Replace the Fe(FeS)C catalyst with Fe 2+ (Using FeSO4 with the same Fe content as in Example 1 as Fe) 2+ source)

[0085] Group D: Replace the Fe(FeS)C catalyst with Fe 3+ (Using Fe2(SO4)3 with the same Fe content as in Example 1, as Fe...) 3+ source).

[0086] Comparative Example 2

[0087] This comparative example constructs a catalytic oxidation wastewater system. The preparation process is similar to that of Example 1, except that in step S1, 2,5-thiophene dicarboxylic acid is not used, but 2,5-furan dicarboxylic acid is used instead. Other raw materials, parameters and steps are the same as in Example 1.

[0088] Performance testing

[0089] The catalytic oxidation wastewater systems constructed in Examples 1-6 and Comparative Examples 1-2 were tested, and the specific results are as follows:

[0090] like Figure 1The image shows a scanning electron microscope (SEM) image of the Fe-MOFs prepared in Example 1 of this invention. It can be seen from the image that there are a large number of active sites on the surface of the material, which can improve the adsorption efficiency and capacity. Its rich mesoporous structure and large specific surface area provide a large number of contact sites for catalytic active species, promote the mass transfer and diffusion of reactants, and thus improve the catalytic reaction kinetics.

[0091] like Figure 2 The figure shows the XRD pattern of Fe(FeS)C prepared in Example 1 of this invention. It can be seen from the figure that the characteristic peaks of the prepared Fe-MOFs match the standard spectrum of Fe-MOFs, indicating that the Fe-MOF precursor was successfully synthesized. After pyrolysis, the peaks at 30.12°, 33.92°, and 43.68° correspond to the (002), (101), and (102) crystal planes of FeS, respectively; the diffraction peaks at 44.9° (110), 65.2° (200), and 82.5° (211) all belong to Fe. 0 The high intensity of the characteristic peak of Fe at a specific angle indicates a high content of Fe, and these results demonstrate the successful preparation of the Fe(FeS)C catalyst.

[0092] like Figure 3 Figure 1 shows the removal efficiency of 2,4-dichlorophenol by the catalytic oxidation wastewater systems constructed in Example 1 and Comparative Examples 1 and 2 of this invention. As can be seen from the figure, Fe(FeS)C alone (Comparative Example 1A) achieved a removal rate of only 40% for 2,4-dichlorophenol; PI alone (Comparative Example 1B) could not remove 2,4-dichlorophenol, with a removal efficiency of 0%, indicating that unactivated PI had virtually no degradation effect; while Fe... 2+ (Comparative Example 1C) Activated PI only achieved a 60% removal rate of 2,4-dichlorophenol. Using Fe... 3+ (Comparative Example 1D) Activated PI showed a 0% removal rate of 2,4-dichlorophenol, indicating that Fe... 2+ It possesses the activity of activating PI, Fe 3+ It completely lacks the ability to activate PI. Furthermore, when using only 2,5-furandicarboxylic acid as a raw material (Comparative Example 2), the removal rate of 2,4-dichlorophenol was 49%, indicating that sulfur participates in the construction of the catalyst's active sites (such as the FeS structure). 2,5-furandicarboxylic acid, lacking sulfur, cannot form similar highly active sites, resulting in weak degradation performance when used alone. In contrast, Fe(FeS)C-activated PI (Example 1) can remove 100% of 2,4-dichlorophenol within 60 minutes, demonstrating the excellent catalytic activity of Fe(FeS)C and its extremely high removal rate of 2,4-dichlorophenol.

[0093] like Figure 4 , 5Fe dissolved from the catalytic oxidation wastewater systems constructed in Example 1 and Comparative Example 1, respectively. 2+ And the total iron concentration. As can be seen from the figure, Fe(FeS)C dissolves only 0.01 mg / L of iron ions, of which Fe... 2+ The concentration was 0.0046 mg / L, indicating that the degradation of 2,4-dichlorophenol by PI activated by Fe(FeS)C was mainly due to the heterogeneous effect of iron on the catalyst surface, rather than the homogeneous effect of iron ions dissolved in the solution.

[0094] like Figure 6 Figure 1 shows the removal effect of the catalytic oxidation wastewater system constructed in Examples 1-4 of this invention on 2,4-dichlorophenol. As can be seen from the figure, the degradation rates of 2,4-dichlorophenol in Examples 1-4 at 60 min were 100%, 98.94%, 100%, and 98.01%, respectively, indicating that the Fe(FeS)C catalyst is effective and the removal rate of 2,4-dichlorophenol is not affected by pH value, and the pH range can reach 3-9.

[0095] like Figure 7 The figure shows the removal effect of the catalytic oxidation wastewater system constructed in Example 5 of the present invention on different pollutants. As can be seen from the figure, the removal rate of Rhodamine B, methylene blue and sulfadimethylpyrimidine can all reach more than 90%, indicating that the system can be applied to the removal of a variety of pollutants.

[0096] like Figure 8 Figure 6 shows the removal effect of the catalytic oxidation wastewater system constructed in Example 6 of this invention on 2,4-dichlorophenol in different water qualities. As can be seen from the figure, the removal effect of the system on 2,4-dichlorophenol reaches 100% in different water qualities, indicating that the Fe(FeS)C / PI system has strong adaptability and a wide range of applications.

[0097] like Figure 9 Figure 1 shows the removal effect of the catalytic oxidation wastewater system constructed in Example 1 of this invention on 2,4-dichlorophenol under different anion conditions. As can be seen from the figure, the removal rate of 2,4-dichlorophenol by the system can reach 100% under different anion conditions, indicating that Fe(FeS)C / PI has a strong anti-interference ability.

[0098] like Figure 10 The figure shows the removal effect of the catalytic oxidation wastewater system constructed in Example 1 of this invention on 2,4-dichlorophenol using different capture agents. As can be seen from the figure, adding different capture agents to the system has varying degrees of inhibitory effect on the removal of 2,4-dichlorophenol. Adding methanol (MeOH) or superoxide dismutase (SOD) to the system significantly reduces the removal effect of 2,4-dichlorophenol, indicating that the activated PI produced ·OH and ·O2.- When methanol (MeOH) or superoxide dismutase (SOD) is added, methanol and SOD specifically capture ·OH and ·O2-, respectively, consuming the key active species in the Fe(FeS)C / PI system used for the degradation of 2,4-dichlorophenol, thus reducing the removal efficiency of the system for 2,4-dichlorophenol. Adding KI to the system does not significantly change the removal efficiency of 2,4-dichlorophenol. This is because the homogeneous effect of dissolved iron generates a small amount of ·OH, limiting the capture effect of KI on ·OH. Furthermore, the degradation of 2,4-dichlorophenol in the system mainly depends on the heterogeneous active sites on the surface of the Fe(FeS)C catalyst, and the heterogeneous... The role of KI is dominant, therefore the addition of KI has a relatively small impact on the overall degradation process. When tert-butanol (TBA) is added to the system, its ability to capture surface-bound ·OH is weak, and it mainly captures free ·OH. As shown in the figure, the degradation rate of the TBA group is higher than that of the methanol group, indicating that ·OH in the system exists more in the catalyst surface bound state than in the free state, further proving that the reaction is mainly in a heterogeneous pathway. When histidine (L-His) is added, the removal efficiency of 2,4-dichlorophenol in this system is significantly reduced, and the removal efficiency of 2,4-dichlorophenol is only 16.14% after 60 min. This is because L-His reacts with the activated PI in the system. 1 O2 preferentially combines with and is consumed. 1 O2, thus significantly reducing the removal efficiency of 2,4-dichlorophenol, indicating 1 O2 is the main free radical scavenger for 2,4-dichlorophenol. A comparison of the removal effects of different scavenging agents on 2,4-dichlorophenol demonstrates their effectiveness in removing free radicals from 2,4-dichlorophenol. 1 O2>·O2 - >·OH, where Fe 0 It undergoes a redox reaction with PI to produce Fe. 2+ and IO3 - Fe 2+ Further reaction with PI to generate ·OH and ·O2 - Meanwhile, S in FeS 2- Fe can be reduced 3+ For Fe 2+ It promotes the formation and decomposition of H2O2 into ·OH; in addition, PI activates the production of 1 O2 oxidizes pollutant molecules through energy transfer, thereby improving the removal efficiency of 2,4-dichlorophenol.

[0099] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for constructing a dual-active-site Fe(FeS)C / PI catalytic oxidation system for wastewater, characterized in that, Follow these steps in sequence: S1. Preparation of Fe(FeS)C catalyst Ferric chloride and 2,5-thiophene dicarboxylic acid were added to dimethylformamide and mixed evenly. Then acetic acid was added, and the mixture was placed in a reaction vessel and reacted at 120 °C for 24 h. After washing three times with anhydrous ethanol, centrifuging and drying, the mixture was placed in a tube furnace and calcined under an inert gas atmosphere to obtain the Fe(FeS)C catalyst. The molar ratio of ferric chloride to 2,5-thiophene dicarboxylic acid, dimethylformamide, and acetic acid is (10-15):(8-10):(385-400):(50-60). The calcination is carried out sequentially according to the following procedure: (a) In the first heating stage, the temperature is increased from room temperature to 450–550 ºC at a heating rate of 5–10 ºC / min, and held for 1–2 hours; (b) In the second heating stage, the temperature is increased from 450–550 ºC to 700–900 ºC at a heating rate of 5–10 ºC / min, and held for 1–2 h; (c) During the cooling stage, the furnace is cooled to room temperature; S2, Construction of catalytic oxidation wastewater system PI was added to 2,4-dichlorophenol, and sulfuric acid and sodium hydroxide were added to adjust the pH to 3-9. Then, Fe(FeS)C catalyst was added to obtain a catalytic oxidation wastewater system.

2. The method for constructing a dual-active-site Fe(FeS)C / PI catalytic oxidation system for wastewater according to claim 1, characterized in that, In step S1, the centrifugation speed is 9000-12000 rpm and the time is 5-10 min.

3. The method for constructing a dual-active-site Fe(FeS)C / PI catalytic oxidation system for wastewater according to claim 1, characterized in that, In step S1, the drying temperature is 80–100 ºC and the drying time is 12–16 h.

4. The method for constructing a dual-active-site Fe(FeS)C / PI catalytic oxidation system for wastewater according to claim 1, characterized in that, In step S2, the molar ratio of PI to 2,4-dichlorophenol and Fe(FeS)C is (1-3):(0.061-0.0615):(0.8-0.85).

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