A tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst and its preparation method and application

Abstract

The present invention discloses a tungsten sulfide-modified iron-based MOF water treatment photo-Fenton catalyst and its preparation method and application. The catalyst is prepared by the following method: adding Fe(NO3)3·9H2O and H3BTC to ultrapure water, then adding WS2, stirring and mixing, heating at 140-160°C for reaction, cooling to room temperature after the reaction, washing and drying the mixture to obtain an orange-red powder, which is a tungsten sulfide-modified MIL100(Fe) photo-Fenton catalyst. The present invention is directed to the treatment of difficult-to-degrade organic pollutants and the application of new MOF materials. Tungsten sulfide and MIL100(Fe) are hydrothermally modified to enhance the stability of the original Fe-MOF material, improve reusability, enhance the scope of photo-Fenton application, and effectively degrade difficult-to-degrade wastewater to protect the environment. The tungsten sulfide-modified MIL100(Fe) photo-Fenton catalyst prepared by this method has significantly improved catalytic H2O2 oxidation performance compared to unmodified MIL100(Fe). The preparation method has the advantages of simple process, wide and cheap raw material sources, low cost, and ease of large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment photo-Fenton catalysts, and in particular relates to a tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Due to industrial and agricultural production and other human activities, the discharge of various organic wastewaters has been increasing. Among them, antibiotic wastewater, dye wastewater, chemical wastewater and other refractory organic wastewaters have been a concern due to their refractory nature. These refractory wastewaters contain a large amount of toxic, carcinogenic and mutagenic substances, and effective treatment is urgent. At present, the main methods for treating refractory wastewater include physical, chemical and biological methods. Among them, advanced oxidation technology, which belongs to the chemical method, produces strong oxidizing ·OH and ·O2 - , O2 and other active substances, which can degrade refractory organic matter and completely mineralize it into non-toxic CO2 and H2O. Advanced oxidation technology is an effective technology for pre-treatment and deep treatment of refractory wastewater, and is also a research hotspot in the field of wastewater treatment. The photo-Fenton technology in the advanced oxidation technology can greatly improve the reaction rate compared with the traditional Fenton / Fenton-like technology because it can use light to accelerate the catalytic oxidation and decomposition of H2O2 to produce active substances. It can also overcome the Fe 2+ The disadvantages include loss, difficulty in reuse, and easy to cause secondary pollution. On this basis, Photo-Fenton can also use light to reduce treatment costs, and has become a key research technology in the field of water treatment in recent years. In addition, Photo-Fenton technology also has the advantages of simple method, wide applicable wastewater pH range, fast reaction rate, easy operation, and non-selective degradation of pollutants. The development trend of Photo-Fenton oxidation technology is still to develop high-performance and low-cost Photo-Fenton catalysts. This process mainly involves the following reactions:

[0003] H2O2+hv→ - OH (1)

[0004] Fe 3+ +hv+H2O→Fe 2+ + - OH+H + (2)

[0005] Fe 2+ +H2O2→Fe 3+ + - OH+OH - (3)

[0006] Metal-organic frameworks (MOFs), as an emerging catalyst, are widely used in photocatalysis and photo-Fenton removal of pollutants. The good photo-Fenton activity of the catalyst is attributed to its rich active site metal oxide clusters, adjustable pore size, and easy-to-design and synthesize heterojunctions. However, the original Fe-MOF still has some defects in its application in the photo-Fenton system. First, due to the poor stability of the original Fe-MOF in water, rapid charge recombination, poor charge separation, and relatively low photocatalytic activity, its application is limited. In order to overcome the above shortcomings and obtain better photocatalytic performance, doping another photocatalyst to modify MOFs is a feasible strategy.

[0007] Transition metal dichalcogenides (TMDs) have been widely studied as promising photocatalysts. WS2 is a member of the TMDs with a high specific surface area. WS2 is widely used in photocatalytic materials due to its broad absorption spectrum. Currently, examples of WS2 composites with Ni-MOF, Zn-MOF, and Uio-66 have been reported. Various applications of composite materials have been achieved, such as dye adsorption, heterogeneous catalysis, sensors, and biomedicine. However, to date, tungsten sulfide-modified MIL100(Fe) composites have not yet been prepared and used for the photo-Fenton degradation of tetracycline and rhodamine B wastewater. Summary of the Invention

[0008] To address the above technical issues, the present invention provides a tungsten sulfide-modified iron-based MOF water treatment photo-Fenton catalyst and its preparation method, as well as its application. Tungsten sulfide is used to modify MIL100(Fe) to enhance the stability of the original Fe-MOF material and improve the photo-Fenton catalytic degradation effect in water treatment.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a tungsten sulfide-modified iron-based MOF photo-Fenton catalyst for water treatment, characterized by the following steps: adding Fe(NO3)3·9H2O and H3BTC to ultrapure water, followed by adding WS2, stirring and mixing, heating at 140-160°C for reaction, cooling to room temperature after the reaction, and washing and drying the mixture to obtain an orange-red powder, which is the tungsten sulfide-modified MIL100(Fe) photo-Fenton catalyst. Fe-MOF is widely used in photo-Fenton processes due to its narrow band gap. Tungsten sulfide modification imparts a porous structure and reversible redox properties to the Fe-MOF. Based on this, a hydrothermal method is a simple and effective method for synthesizing functional materials or composite materials through simple operations. The hydrothermal method allows tungsten sulfide to come into close contact with MIL100(Fe), forming a composite material with enhanced photo-Fenton activity.

[0010] In the above scheme, the molar ratio of Fe(NO3)3·9H2O to H3BTC is 1:0.6-0.7, and the molar ratio of tungsten sulfide to Fe(NO3)3·9H2O is 0.025-0.15.

[0011] In the above scheme, the reaction time is 10-20 hours to ensure sufficient reaction.

[0012] In the above scheme, ethanol and ultrapure water are used for washing. Ultrapure water can be used for washing first, and ethanol can be used for washing at least for the last time. Ethanol has a low boiling point and is easier to dry.

[0013] In the above scheme: the drying temperature is 50-70°C and the drying time is not less than 24 hours.

[0014] A tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst is prepared by a preparation method of the tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst.

[0015] The tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst is used in water treatment to catalyze hydrogen peroxide to degrade refractory organic matter under light.

[0016] In the above scheme: the refractory organic matter is rhodamine B and tetracycline hydrochloride.

[0017] The tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst is used to catalyze the degradation of rhodamine B by hydrogen peroxide under light in water treatment.

[0018] Compared with existing technologies, the present invention offers the following advantages: It targets the treatment of refractory organic pollutants and the application of novel MOF materials. Hydrothermal modification of tungsten sulfide and MIL100(Fe) enhances the stability of the original Fe-MOF material, improves its reusability, expands its photo-Fenton application range, and effectively degrades refractory wastewater, protecting the environment.

[0019] The tungsten sulfide modified MIL100(Fe) photo-Fenton catalyst prepared by this method has significantly improved catalytic H2O2 oxidation performance compared with the unmodified MIL100(Fe). The preparation method has the advantages of simple process, wide and cheap raw material sources, low cost, and easy large-scale industrial production.

[0020] The prepared tungsten sulfide modified MIL100 (Fe) photo-Fenton catalyst has high activity. The present invention provides a new technology for the simple preparation of new materials and the treatment of refractory wastewater, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1is the X-ray powder diffraction (XRD) spectrum of MIL100(Fe) / WS2-MIL100(Fe) (WS2 2mM).

[0022] Figure 2 This is the FT-IR spectrum of MIL100(Fe) / WS2-MIL100(Fe) (WS2 2mM).

[0023] Figure 3 The degradation effect of TC by WS2-MIL100(Fe) with different mass modifications (a) and its kinetic curve (b).

[0024] Figure 4 The degradation effects of TC under different conditions (a) and its kinetic curve (b) (WS22mM).

[0025] Figure 5 The degradation effects of RhB under different conditions (a) and its kinetic curve (b) (WS22mM). DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Example 1: Treatment of simulated antibiotic wastewater using WS2-MIL100(Fe) photo-Fenton catalyst

[0028] 1) Preparation process

[0029] 20 mM Fe(NO₃)₃·9H₂O and 13.4 mM H₃BTC were added to 60 mL of ultrapure water. Tungsten sulfide was then added at 0.5 mM, 1 mM, 2 mM, and 3 mM concentrations, respectively. The resulting solution was then transferred to a 100 mL Teflon-lined stainless steel autoclave and heated at 150°C for 12 hours. After cooling to room temperature, the solution was centrifuged and washed multiple times with ethanol and ultrapure water, with at least the last wash being ethanol. Finally, the solution was dried at 50-70°C for 24 hours to yield an orange-red solid, the WS₂-MIL100(Fe) composite photo-Fenton catalyst.

[0030] First, the crystal structure of the MIL100(Fe) / WS2-MIL100(Fe) catalyst was analyzed by X-ray diffraction (XRD, the vertical axis is intensity). Figure 1The X-ray powder diffraction (XRD) spectrum of WS2 at 2 mM is shown. The diffraction peaks at 2θ = 13.6°, 32.9°, and 58.6° are assigned to the (002), (004), and (008) crystal planes, respectively. These peaks are consistent with those in PDF#08-0237, while the main characteristic peaks of the prepared MIL100(Fe) at 6.2°, 10.2°, 11.0°, and 20.0° are consistent with the characteristic peaks of MIL100(Fe) reported in the literature. The XRD of WS2 has four obvious diffraction peaks at 2θ = 14.3°, 29.4°, 33.5°, and 38.4°, 48.3°, corresponding to the (003), (006), (111), (004), and (104) crystal planes, respectively (PDF#35-0651). In WS2-MIL100(Fe), the characteristic peaks of the original MIL100(Fe) were retained, while the characteristic peaks of WS2 appeared, indicating the effective synthesis of WS2-MIL100(Fe).

[0031] The Fourier transform infrared spectroscopy (FT-IR) of the synthesized material (WS22mM) is shown in Figure 2. Figure 2 As shown. 1640cm -1 is the stretching vibration peak of C=O bond, 1380cm -1 is the stretching vibration peak of CO, 711 cm -1 The peak at 450-900 cm is the stretching vibration of the benzene ring. -1 The peak in the range is WOW stretching vibration. -1 The characteristic peak of WS at can be clearly observed, further proving the successful synthesis of tungsten sulfide modified MIL100 photo-Fenton catalyst.

[0032] 2) Used in tetracycline hydrochloride degradation test

[0033] 20 mg of the above-synthesized photo-Fenton catalyst with different WS2 addition amounts were added to 100 mL of the solution with an initial concentration of 40 mg.L -1 The suspension was stirred in the dark to reach adsorption-desorption equilibrium. Then, 48.95 mmol.L of tetracycline hydrochloride (TC) solution was added under visible light irradiation using a 300W Xe lamp. -1 H2O2 (30% by mass) was added to the suspension in the reactor. 2-4 mL of the reaction solution was sampled at regular intervals, centrifuged, and filtered to remove solids. The TC concentration at different treatment times was measured spectrophotometrically.

[0034] Figure 3The degradation effect of TC on WS2-MIL100(Fe) with different mass modifications (a) and its kinetic curve (b) are shown. Generally speaking, the performance of the catalyst varies with the composition of the material. The photo-Fenton TC degradation efficiency of WS2-MIL100(Fe) catalysts with different mass ratios under a xenon lamp light source is shown in the figure. When the mass of WS2 is 2mM, the adsorption efficiency is low and the degradation efficiency is the best. The tungsten content in the catalyst also increases with the increase of WS2, which mainly affects the adsorption performance of the catalyst. However, with the further increase of WS2, the TC removal rate is inhibited. This is because the increase of WS2 affects the exposed active sites of MIL100(Fe), reducing the removal rate of TC.

[0035] Figure 4 The degradation effect of WS2-MIL100(Fe) on TC prepared under different conditions with a mass of 2 mM WS2 (a) and its kinetic curve (b) are shown. K represents the reaction rate constant. The removal rate of TC can reach 93.2% after 40 min of treatment with WS2-MIL100(Fe). The reaction rate constant k is 0.0688 min -1 The one-hour removal rate of the unmodified MIL100(Fe) catalyst was only 69%. The reaction rate constant k was 0.0240 min -1 The rate constant of WS2 catalyst is k = 0.00357 min -1 The rate constant of WS2-MIL100(Fe) was significantly improved.

[0036] 3) Degradation of RhB by WS2-MIL100(Fe) prepared with WS2 mass of 2 mM

[0037] 20 mg of the above-synthesized photo-Fenton catalyst was added to 100 mL of the solution to an initial concentration of 40 mg.L -1 The suspension was stirred in the dark to reach adsorption-desorption equilibrium. Then, 48.95 mmol·L of Rhodamine B (RhB) was added under visible light irradiation using a 300W Xe lamp. -1 H2O2 (30% by mass concentration of hydrogen peroxide) was added to the suspension in the reactor. 2-4 mL of the reaction solution was sampled at regular intervals, centrifuged, and filtered to remove the solids. The RhB concentration at different treatment times was measured by spectrophotometry. Figure 5 As shown in Figure 2 (where k represents the rate reaction constant), the removal rate of RhB can reach 97.2% after 40 minutes of treatment with WS2-MIL 100 (Fe) catalyst, and the reaction rate constant k is 0.0862 min -1The removal rate of MIL100(Fe) catalyst is also 89.7%. However, its reaction rate constant k is only 0.0471min -1 The reaction rate of WS2-MIL100(Fe) increased by nearly 1 times compared with that of MIL100(Fe) catalyst, and the WS2-MIL100(Fe) composite catalyst significantly improved the photo-Fenton catalytic effect.

[0038] Example 2

[0039] 20 mM Fe(NO₃)₃·9H₂O and 14 mM H₃BTC were added to 60 mL of ultrapure water. Then, 2 mM tungsten sulfide was added. The resulting solution was transferred to a 100 mL Teflon-lined stainless steel autoclave and heated at 160°C for 10 hours. After cooling to room temperature, the solution was centrifuged and washed multiple times with ethanol and ultrapure water, with at least the last wash being ethanol. Finally, the solution was dried at 50-70°C for 24 hours to obtain an orange-red solid, the WS₂-MIL100(Fe) composite photo-Fenton catalyst.

[0040] According to the method of Example 1, TC was catalyzed for degradation, and the removal rate of TC could reach 93.8% after 40 minutes of treatment.

[0041] Example 3

[0042] 20 mM Fe(NO₃)₃·9H₂O and 12 mM H₃BTC were added to 60 mL of ultrapure water. Then, 2 mM tungsten sulfide was added. The resulting solution was transferred to a 100 mL Teflon-lined stainless steel autoclave and heated at 150°C for 20 hours. After cooling to room temperature, the solution was centrifuged and washed multiple times with ethanol and ultrapure water, with at least the last wash being ethanol. Finally, the solution was dried at 50-70°C for 24 hours to obtain an orange-red solid, the WS₂-MIL100(Fe) composite photo-Fenton catalyst.

[0043] According to the method of Example 1, TC was catalyzed for degradation, and the removal rate of TC could reach 92.1% after 40 minutes of treatment.

Claims

1. A method for preparing a tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst, characterized in that: The preparation method is as follows: Fe(NO3)3·9H2O and H3BTC are added to ultrapure water, and then WS2 is added, the mixture is stirred and mixed evenly, and the mixture is heated at 140-160°C for reaction. After the reaction is completed, the mixture is cooled to room temperature, and the mixture is washed and dried to obtain an orange-red powder, which is tungsten sulfide modified MIL100(Fe) photo-Fenton catalyst. The molar ratio of tungsten sulfide to Fe(NO3)3·9H2O is 0.025-0.

15.

2. The method for preparing the tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst according to claim 1, characterized in that: The molar ratio of Fe(NO3)3·9H2O to H3BTC is 1:0.6-0.

7.

3. The method for preparing the tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst according to claim 1 or 2, characterized in that: Reaction time: 10-20h.

4. The method for preparing the tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst according to claim 3, characterized in that: Wash with ethanol and ultrapure water.

5. The method for preparing the tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst according to claim 4, characterized in that: The drying temperature is 50-70℃ and the drying time is not less than 24h.

6. A tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst prepared by the preparation method of the tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst according to any one of claims 1 to 5.

7. Use of the tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst according to claim 6 as a photo-Fenton catalyst in water treatment.

8. The use according to claim 7, characterized in that: The tungsten sulfide modified iron-based MOF water treatment photo-Fenton catalyst is used in water treatment to catalyze hydrogen peroxide to degrade refractory organic matter under light.

9. The application according to claim 8, characterized in that: The refractory organic matter is rhodamine B and tetracycline hydrochloride.

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