Supercritical sulfuration MOFs fenton catalyst and preparation method and application thereof

Abstract

The application discloses a kind of supercritical sulphurization MOFs fenton catalyst and its preparation method and application, the preparation method of catalyst includes: m-phenylenediamine and iron powder are added to deionized water to obtain precursor solution;The precursor solution is hydrothermally reacted to obtain MOFs precursor;Precursor is activated and then supercritical sulphurization is carried out, to obtain supercritical sulphurization MOFs.The catalyst of the application is synthesized by green and environmentally friendly method, has super-high degradation performance to bisphenol A, and has good stability.In addition, the supercritical sulphurization method in the application effectively penetrates sulfur into the inner pores and interlayers of MOFs, greatly improves the loading capacity and uniform distribution of sulfur, and enriches active sites.

Description

Technical Field

[0001] This invention belongs to the technical field of Fe-MOFs-type Fenton catalytic materials, specifically relating to a supercritical sulfided MOFs-type Fenton catalyst, its preparation method, and its application. Background Technology

[0002] Bisphenol A (BPA) is an important organic chemical raw material and a significant derivative of phenol and acetone. It is primarily used as a raw material in the synthesis of epoxy resins, polycarbonates, polysulfones, aromatic polyesters, phenolic resins, unsaturated polyester resins, and flame retardants. However, it is also an endocrine disruptor; as a foreign compound, it affects hormone activity, causing numerous adverse consequences in the endocrine system, thus impacting the health of the organism, its offspring, or (sub)population. These compounds have been found in aquatic environments, including groundwater, surface water, runoff, wastewater, landfill leachate, and drinking water. Therefore, finding environmentally friendly methods to rapidly and effectively degrade BPA or its oxidation intermediates is crucial for both human health and the environment.

[0003] Natural pyrite is considered an excellent candidate because, with the oxidation of sulfur, H... + Iron ions are also released, lowering the solution pH and providing an iron source. Although pyrite exhibits better Fenton properties, it also suffers from the problem of excessive iron leaching. Summary of the Invention

[0004] In view of the above-mentioned technical problems existing in the prior art, the purpose of this invention is to provide a supercritical sulfurized MOFs, its preparation method and application.

[0005] The technical solution adopted in this invention is as follows:

[0006] A method for preparing a supercritical sulfided MOF-type Fenton catalyst includes the following steps:

[0007] 1) Tristyric acid and iron powder were added to deionized water as a precursor solution. The precursor solution was subjected to hydrothermal reaction to obtain MOF precursor. The MOF precursor was then activated to obtain CUS-MIL-100(Fe) solid.

[0008] 2) Mix CUS-MIL-100(Fe) solid and sublimed sulfur and transfer to a stainless steel ball mill jar. Pump CO2 gas into the ball mill jar until a supercritical state is formed. Transfer the ball mill jar to a ball mill and grind at a certain speed at room temperature. After that, release the CO2 gas to obtain supercritical sulfurized MOFs.

[0009] Further, in step 1), the molar ratio of iron powder to trimesic acid is 1:0.5-1, preferably 1:0.6-0.7.

[0010] Further, the specific operation steps of step 1) are as follows: Reduced iron powder and pyromellitic acid are mixed in deionized water, stirred and mixed at room temperature, HNO3 and HF are added, and stirring is continued for at least 30 minutes. Then, the mixture is placed in a reaction vessel for hydrothermal reaction. After the reaction vessel is naturally cooled to room temperature, the precipitate is filtered and recovered. The product is washed to remove residual organic matter, and finally vacuum dried to obtain CUS-MIL-100(Fe) solid.

[0011] Furthermore, the molar ratio of iron powder to HNO3 is 1:0.5-1, preferably 1:0.6-0.7; the molar ratio of iron powder to HF is 1:1-4, preferably 1:2-2.5; the hydrothermal reaction temperature is 140-160℃, preferably 150℃; and the reaction time is 10-15h, preferably 12-13h.

[0012] Further, in step 2), the mass ratio of the CUS-MIL-100(Fe) solid to sublimed sulfur is (1.5-2)g:(0.37-4)g, preferably 2:0.5-0.6, the CO2 pressure in the ball mill is 7.0-8.5 MPa, preferably 7.8-8 MPa, and the rotation speed of the ball mill is 300-400 rpm, preferably 350 rpm.

[0013] The present invention also provides the application of the supercritical sulfurized MOFs-like Fenton catalyst in the catalytic oxidation degradation of organic pollutants in wastewater. The application method is as follows: the Fenton-like catalyst is added to organic pollutant wastewater with a pH of 4 to 10, and H2O2 with a final concentration of 0.5 to 10 mM is added to it. The degradation experiment is carried out in a shaker at 200-3000 rpm and a temperature of 15 to 35°C. After the reaction is completed, solid-liquid separation is performed, and the supercritical sulfurized MOFs material is recovered.

[0014] Furthermore, the pH of the organic pollutant wastewater is 4-7, and the dosage of the Fenton-like catalyst in the wastewater is 0.1-0.5 g / L. The organic pollutant wastewater includes bisphenol A, and the concentration of organic pollutants in the wastewater is 10-50 mg / L.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0016] 1) The supercritical sulfurized MOFs of the present invention have the characteristics of strong catalytic activity, good stability, low cost and low environmental hazard; at the same time, the supercritical sulfurization method allows sulfur to effectively penetrate into the internal pores and interlayers of MOFs, which greatly improves the sulfur loading and uniform distribution and enriches the active sites.

[0017] 2) The supercritical sulfide MOFs of this invention are synthesized using a green and environmentally friendly method, and exhibit ultra-high catalytic degradation performance for organic pollutants, along with a long catalytic lifetime. They have a very broad application prospect in the catalytic oxidation treatment of organic pollutants in wastewater. Compared to commercially available pyrite, the supercritical sulfide MOFs of this invention show significantly improved degradation efficiency, reusability, and stability. Attached Figure Description

[0018] Figure 1 The image shown is a scanning electron microscope image of CUS-MIL-100(Fe) obtained in step a of Example 1;

[0019] Figure 2 The SC-MIL-100(Fe)@S obtained in step b of Example 1 0.25 Scanning electron microscope image;

[0020] Figure 3 The SC-MIL-100(Fe)@S obtained in step b of Example 1 0.25 XRD pattern;

[0021] Figure 4 The SC-MIL-100(Fe)@S obtained in step b of Example 1 0.25 Fe 2p XPS plot;

[0022] Figure 5 The graph shows the degradation effect of different catalytic materials on bisphenol A in water in Example 1.

[0023] Figure 6 The SC-MIL-100(Fe)@S obtained in step b of Example 1 0.25 Graphs showing the degradation effect of bisphenol A in water under different pH conditions;

[0024] Figure 7 The SC-MIL-100(Fe)@S obtained in step b of Example 1 0.25 Figures showing the degradation effect of bisphenol A in water under different catalyst dosages;

[0025] Figure 8 The SC-MIL-100(Fe)@S obtained in step b of Example 1 0.25 A graph showing the effect of cyclic testing on the degradation of bisphenol A in water.

[0026] Figure 9 The SC-MIL-100(Fe)@S obtained in step b of Example 1 0.25 Graph showing iron ion leaching during the degradation of bisphenol A in water. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0028] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0029] Example 1

[0030] The preparation method of this supercritical sulfurized MOFs includes the following steps:

[0031] a. Mix 0.82g of reduced iron powder and 2.06g of trimesic acid in 80ml of deionized water. Stir magnetically for 30min at room temperature, then add dropwise 1.14ml of HNO3 solution (65-68% by mass) and 0.6ml of HF solution (40% by mass), and continue stirring for 1h. Transfer the reaction mixture to a stainless steel reactor lined with a 100ml dry polytetrafluoroethylene liner, and place it in a programmable temperature-controlled electric thermostatic drying oven. React at 150℃ for 24h. After the reactor cools naturally to room temperature, filter and recover the resulting pale orange precipitate. Stir in hot deionized water at 80℃ for 5h and hot ethanol at 60℃ for 3h respectively to remove residual reactants and colored impurities. Finally, the product was vacuum dried in a 70℃ vacuum drying oven for 12 h to obtain the MIL-100(Fe) catalyst. Subsequently, MIL-100(Fe) was vacuum activated at 220℃ for 12 h to obtain CUS-MIL-100(Fe). The scanning electron microscope image of the activated MIL-100(Fe) is shown below. Figure 1 As shown, CUS-MIL-100(Fe) exhibits a typical cubic octahedral structure with a rough surface.

[0032] b. CUS-MIL-100(Fe) and sublimed sulfur were mixed at a mass ratio of 2:0.5 and transferred to a stainless steel ball mill jar. CO2 was then pumped into the jar until the pressure reached 8.0 MPa. The jar was then milled at 350 rpm for 12 hours at room temperature. Afterward, the CO2 was rapidly released, finally yielding SC-MIL-100(Fe)@S 0.25 .

[0033] Similarly, in this embodiment, different supercritical sulfidation MOFs-like Fenton catalysts SC-MIL-100(Fe) and SC-MIL-100(Fe)@S were prepared at different CUS-MIL-100(Fe) and sublimed sulfur mass ratios. 0.16 SC-MIL-100(Fe)@S 0.5 SC-MIL-100(Fe)@S1 and SC-MIL-100(Fe)@S2, which are related to SC-MIL-100(Fe)@S0.25 The only difference in the preparation methods is that the mass ratios of CUS-MIL-100(Fe) and sublimed sulfur are 2:0, 2:0.32, 2:1, 2:2, and 2:4, respectively.

[0034] The obtained SC-MIL-100(Fe)@S 0.25 Scanning electron microscope image as follows Figure 2 As shown, it can be observed that the original octahedral MIL-100(Fe) becomes some smaller cracked particles after supercritical sulfidation, which can provide more active sites for the reaction system when used as a catalyst.

[0035] The obtained SC-MIL-100(Fe)@S 0.25 XRD such as Figure 3 As shown, the supercritically sulfided CUS-MIL-100(Fe) has similar characteristic peaks to CUS-MIL-100(Fe), indicating that the crystal structure of the framework is well preserved.

[0036] The obtained SC-MIL-100(Fe)@S 0.25 XPS such Figure 4 As shown, this illustrates SC-MIL-100(Fe)@S 0.25 The Fe in the material has valence states of +2 and +3.

[0037] Example 2

[0038] The supercritical sulfurized MOFs prepared in Example 1 were applied to the catalytic oxidation of bisphenol A-containing wastewater using a Fenton-like reaction. The experimental process of the catalytic oxidation of bisphenol A using a Fenton-like reaction included the following steps:

[0039] 20 mg of the supercritical sulfurized MOFs prepared in Example 1 was added to 100 ml of a bisphenol A solution with an initial concentration of 20 mg / L and a pH of 7. The experiment was conducted in a shaker at 250 rpm and 25 °C. After starting the shaker, 3 mM H2O2 was added to the reaction system to begin the degradation of bisphenol A in the water, and the reaction time was 30 min. After the reaction was completed, solid-liquid separation was performed, and the catalyst material in the above reaction process was recovered.

[0040] In the Fenton-like catalytic reaction, 1 ml samples were taken at reaction times of 0 min, 2 min, 5 min, 10 min, 20 min, and 30 min, and 0.5 ml of methanol was added for quenching. The concentration of bisphenol A was then measured by liquid chromatography, and the degradation rate of bisphenol A in water by different catalytic materials was calculated.

[0041] Figure 5 This image shows the degradation effect of different catalytic materials on bisphenol A in water in Experimental Example 1 of this invention. Figure 5 It can be seen that, compared with supercritical sulfurized MOFs of other mass ratios, SC-MIL-100(Fe)@S 0.25 It exhibits better degradation effect on bisphenol A; the improvement in degradation effect is more significant. Under the conditions of catalyst concentration = 0.2 g / L, H2O2 concentration = 3 mM, initial pH = 7, temperature = 25℃, and BPA concentration = 20 mg / L, a degradation rate of 98% is achieved within 20 minutes.

[0042] Example 3

[0043] This example provides a method for using SC-MIL-100(Fe)@S prepared in Example 1. 0.25 The specific method for applying catalytic materials to treat organic pollutants at initial pH is as follows:

[0044] The specific steps are basically the same as those in Example 2, the only difference being that the initial pH values ​​of the reaction solutions are 4, 5, 7, 9, and 10, respectively. The degradation rates of bisphenol A by the catalytic material at different pH values ​​are as follows: Figure 6 As shown.

[0045] Figure 6 The SC-MIL-100(Fe)@S in Embodiment 1 of the present invention 0.25 Degradation effects of bisphenol A in water bodies at different pH values. Figure 6 It can be seen that SC-MIL-100(Fe)@S 0.25 The degradation rates of bisphenol A at pH 4, 5, 7, 9, and 10 for 20 min were 99.8%, 98.9%, 98%, 64.8%, and 37.4%, respectively, indicating that acidic reaction systems with lower pH values ​​are more conducive to the Fenton-like reaction.

[0046] Example 4

[0047] This example provides a method for using SC-MIL-100(Fe)@S prepared in Example 1. 0.25 The application of catalytic materials in treating organic pollutants under different catalyst dosages is specifically described as follows:

[0048] The specific steps are basically the same as those in Example 2, except that the catalyst dosage is 0.05, 0.1, 0.2, and 0.4 g / L, respectively. The degradation rate of bisphenol A by the catalytic material under different catalyst dosages is as follows: Figure 7 As shown.

[0049] Figure 7 The SC-MIL-100(Fe)@S in Embodiment 1 of the present invention 0.25 Degradation effects of bisphenol A under different catalyst dosages. Figure 7It can be seen that SC-MIL-100(Fe)@S 0.25 The degradation rates of bisphenol A were 26.9%, 92.6%, 100%, and 100% when the catalyst dosage was 0.05, 0.1, 0.2, and 0.4 g / L, respectively. The catalyst dosage affected the degradation effect of bisphenol A, and the degradation effect increased with the increase of catalyst dosage.

[0050] Example 5

[0051] This example provides a method for using SC-MIL-100(Fe)@S prepared in Example 1. 0.25 The application of treating organic pollutants through five cycles follows the same steps as in Example 2. After each use, the catalytic material is filtered and recovered, then dried in a vacuum oven for use in the next experiment.

[0052] Figure 8 The SC-MIL-100(Fe)@S in Embodiment 1 of the present invention 0.25 Degradation effect of bisphenol A during 5 recycling cycles. (Image from...) Figure 8 It can be seen that after 5 cycles, SC-MIL-100(Fe)@S 0.25 The degradation effect on bisphenol A decreased slightly, but remained above 92.8%, indicating that the SC-MIL-100(Fe)@S in this invention... 0.25 Reusability.

[0053] Example 6

[0054] This example tests the SC-MIL-100(Fe)@S prepared in Example 1. 0.25 The method described in Example 5, which involves treating the amount of iron ions leaked during the process of treating organic pollutants through five cycles, is as follows:

[0055] At each sampling, 5 ml of waste liquid was placed in a centrifuge tube (without quenching agent), and the iron ion concentration was measured using an atomic absorption spectrophotometer. Example 1: Preparation of SC-MIL-100(Fe)@S 0.25 The dosage was 0.2 g / L, the H₂O₂ dosage was 3 mM, the aqueous solution temperature was 25℃, and the initial pH of the solution was 7. The test results are as follows: Figure 9 As shown, the highest concentration of iron ions leaked from SC-MIL-100(Fe)@S0.25 prepared in Example 1 during 5 cycles of use was 1.68 mg / L, which is lower than the EU environmental standard (2 mg / L). Therefore, SC-MIL-100(Fe)@S 0.25 The fact that the iron ions leaked during the catalytic oxidation of bisphenol A do not cause secondary pollution also demonstrates that the material has good stability.

[0056] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A method for the preparation of a supercritical sulfidized MOFs Fenton-like catalyst, characterized by The method comprises the following steps: 1) adding iron powder and trimesic acid into deionized water as a precursor solution, and performing hydrothermal reaction on the precursor solution to obtain a MOFs precursor, and then activating the MOFs precursor to obtain a CUS-MIL-100(Fe) solid; 2) mixing the CUS-MIL-100(Fe) solid and sublimed sulfur, and transferring them into a stainless steel ball mill jar, pumping CO2 gas into the ball mill jar to form a supercritical state, and transferring the ball mill jar to a ball mill, and grinding the ball mill at a certain speed at room temperature; then, releasing the CO2 gas, and obtaining a supercritical sulfurized MOFs. In step 2), the mass ratio of the CUS-MIL-100(Fe) solid to the sublimed sulfur is 2:0.5-0.

6.

2. A method of preparing a supercritical sulfidized MOFs Fenton-like catalyst according to claim 1, characterized in that In step 1), the molar ratio of the iron powder to the trimesic acid is 1:0.5-1.

3. A method of preparing a supercritical sulfidized MOFs Fenton-like catalyst according to claim 2, characterized in that In step 1), the molar ratio of the iron powder to the trimesic acid is 1:0.6-0.

7.

4. A method of preparing a supercritical sulfidized MOFs Fenton-like catalyst according to claim 1, characterized in that The specific operation steps of step 1) are as follows: mixing the reduced iron powder and the trimesic acid in deionized water, stirring the mixture at room temperature, adding HNO3 and HF, continuously stirring for at least 30 min, then placing the mixture in a reaction kettle for hydrothermal reaction, naturally cooling the reaction kettle to room temperature, filtering and recovering the obtained precipitate, washing the product to remove residual organic matter, and finally vacuum drying to obtain the CUS-MIL-100(Fe) solid.

5. A method of preparing a supercritical sulfidized MOFs Fenton-like catalyst according to claim 4, characterized in that The molar ratio of the iron powder to HNO3 is 1:0.8-1.5, the molar ratio of the iron powder to HF is 1:1-4, the hydrothermal reaction temperature is 140-160℃, and the reaction time is 10-15 h.

6. A method of preparing a supercritical sulfidized MOFs Fenton-like catalyst according to claim 5, characterized in that The molar ratio of the iron powder to HNO3 is 1:1.0-1.2, the molar ratio of the iron powder to HF is 1:2-2.5, the hydrothermal reaction temperature is 150℃, and the reaction time is 12-13 h.

7. A method of preparing a supercritical sulfidized MOFs Fenton-like catalyst according to claim 1, characterized in that In step 2), the pressure of CO2 in the ball mill jar is 7.0-8.5 MPa, and the speed of the ball mill is 300-400 rpm.

8. A method of preparing a supercritical sulfidized MOFs Fenton-like catalyst according to claim 7, characterized in that In step 2), the pressure of CO2 in the ball mill jar is 7.8-8 MPa, and the speed of the ball mill is 350 rpm.

9. A supercritical sulfurized MOFs Fenton-like catalyst prepared by the method of any one of claims 1-8.

10. The use of the supercritical sulfurized MOFs Fenton-like catalyst of claim 9 in catalytic oxidation degradation of organic pollutants in wastewater.

11. Use according to claim 10, wherein The Fenton-like catalyst is added to organic pollutant wastewater with a pH of 4-10, and a final concentration of 0.5-10 mM H2O2 is added to the wastewater, and the degradation experiment is carried out in a shaking bed at 200-3000 rpm and a temperature of 15-35℃, and after the reaction is completed, solid-liquid separation is carried out, and the supercritical sulfurized MOFs material is recovered.

12. The use according to claim 11, wherein The pH of the organic pollutant wastewater is 4-7, and the dosage of the Fenton-like catalyst in the wastewater is 0.1-0.5 g / L.

13. The use according to claim 12, wherein The organic pollutant wastewater includes bisphenol A, and the concentration of the organic pollutant in the wastewater is 10-50 mg / L.

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